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  • Articles  (256)
  • Mice  (181)
  • evolution  (64)
  • Cell & Developmental Biology
  • Elasticity
  • LUNAR AND PLANETARY EXPLORATION
  • 2000-2004  (256)
  • 1995-1999
  • 1935-1939
  • 2000  (256)
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  • 2000-2004  (256)
  • 1995-1999
  • 1935-1939
Year
Journal
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Die Lage der Vogelsystematik (2000)
    Springer
    Journal of ornithology 141 (2000), S. 263-274 
    Details
    ISSN: 1439-0361
    Keywords: Systematics ; evolution ; anagenesis ; genealogy ; reference system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Verglichen mit anderen Tiergruppen, scheint die artliche Bestandsaufnahme der rezenten Vögel nahezu abgeschlossen zu sein. Doch ist das System der Vögel weiterhin umstritten und mit vielen Neuerungen konfrontiert. Die Gründe dafür liegen hauptsächlich in neuen, vor allem molekularbiologischen Methoden und in den unerwartet reichen Fossilfunden der jüngsten Zeit. Als Beispiele werden Altgaumenvögel, Kranichvögel, Ibisse, Flamingos, Mausvögel, Hopfe und Sperlingsvögel kurz behandelt. Die hier erzielten Fortschritte lassen die Befürchtung Stresemanns, die Großsystematik der Vögel sei mit den vorhandenen Methoden phylogenetisch nicht interpretierbar, zunächst als unbergründet erscheinen. Doch erwachsen einer solchen Interpretation andere Hindernisse, deren Bedeutung bisher zu wenig beachtet wurde, nämlich Parallelentwicklungen, die viel verbreiteter sind als gemeinhin angenommen. Ihre Häufigkeit lässt sich sogar mit evolutionsbiologischen Argumenten begründen. Es ist deshalb nicht zu erwarten, dass die Diskussionen um das „richtige“ System bald verstummen. Um dennoch die Eindeutigkeit der Information in nicht-systematischen Veröffentlichungen zu wahren, wird empfohlen ein etabliertes Referenzsystem auf Zeit zu wählen.
    Notes: Summary Unlike in most animal classes the inventory of extant species of the class Aves seems to be almost complete. Nevertheless avian systematics is challenged by many novelties and seems far from being settled. This is caused mainly by the application of novel methods of molecular analysis to phylogenetic problems and by the unexpectedly rich fossil record collected within the last 10–20 years. Examples from the Palaeognathae, Gruiformes, Threskiornithidae, Phoenicopteridae, Coliiformes, Upupiformes and Passeriformes are briefly treated. The progress in the field seems to disprove Stresemann's pessimistic view that the phylogeny of higher categories (orders) cannot be reconstructed by the available methods. However, phylogenetic interpretations are impeded by obstacles not considered by Stresemann and highly underestimated in most cases, namely by multiple independent developments leading to identical features. Frequent parallel developments are to be expected for theoretical evolutionary reasons. The diagnosis of such homoplasies can be extremely difficult or even impossible. Therefore we cannot expect the discussion about the “best” system of birds to end in the near future. Considering this dynamic situation in systematics, it is recommended to maintain unambiguousness of information in not strictly systematic publications by refering to a well established system as a temporally limited reference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02462236
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  • 2
    Electronic Resource
    Electronic Resource
    Emergence and Maintenance of Sex among Diploid Organisms Aided by Assortative Mating (2000)
    Springer
    Acta biotheoretica 48 (2000), S. 137-147 
    Details
    ISSN: 1572-8358
    Keywords: Sex ; sexual selection ; mate selection ; evolution ; ploidy ; assortative mating ; recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using computer simulations I studied the simultaneous effect of variable environments, mutation rates, ploidy, number of loci subject to evolution and random and assortative mating on various reproductive systems. The simulations showed that mutants for sex and recombination are evolutionarily stable, displacing alleles for monosexuality in diploid populations mating assortatively under variable selection pressure. Assortative mating reduced excessive allelic variance induced by recombination and sex, especially among diploids. Results suggest a novel adaptive value for sex and recombination. They show that the adaptive value of diploidy and that of the segregation of sexes is different to that of sex and recombination. The results suggest that the emergence of sex had to be preceded by the emergence of diploid monosexual organisms and provide an explanation for the emergence and maintenance of sex among diploids and for the scarcity of sex among haploid organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002765101959
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  • 3
    Electronic Resource
    Electronic Resource
    Multitrophic effects of herbivore-induced plant volatiles in an evolutionary context (2000)
    Springer
    Entomologia experimentalis et applicata 97 (2000), S. 237-249 
    Details
    ISSN: 1570-7458
    Keywords: herbivores ; predators ; parasitoids ; mutualism ; induced defence ; behaviour ; ecology ; evolution ; sensory physiology ; plant fitness ; pathogens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Herbivorous and carnivorous arthropods use plant volatiles when foraging for food. In response to herbivory, plants emit a blend that may be quantitatively and qualitatively different from the blend emitted when intact. This induced volatile blend alters the interactions of the plant with its environment. We review recent developments regarding the induction mechanism as well as the ecological consequences in a multitrophic and evolutionary context. It has been well established that carnivores (predators and parasitoids) are attracted by the volatiles induced by their herbivorous victims. This concerns an active plant response. In the case of attraction of predators, this is likely to result in a fitness benefit to the plant, because through consumption a predator removes the herbivores from the plant. However, the benefit to the plant is less clear when parasitoids are attracted, because parasitisation does usually not result in an instantaneous or in a complete termination of consumption by the herbivore. Recently, empirical evidence has been obtained that shows that the plant's response can increase plant fitness, in terms of seed production, due to a reduced consumption rate of parasitized herbivores. However, apart from a benefit from attracting carnivores, the induced volatiles can have a serious cost because there is an increasing number of studies that show that herbivores can be attracted. However, this does not necessarily result in settlement of the herbivores on the emitting plant. The presence of cues from herbivores and/or carnivores that indicate that the plant is a competitor- and/or enemy-dense space, may lead to an avoidance response. Thus, the benefit of emission of induced volatiles is likely to depend on the prevailing faunal composition. Whether plants can adjust their response and influence the emission of the induced volatiles, taking the prevalent environmental conditions into account, is an interesting question that needs to be addressed. The induced volatiles may also affect interactions of the emitting plant with its neighbours, e.g., through altered competitive ability or by the neighbour exploiting the emitted information. Major questions to be addressed in this research field comprise mechanistic aspects, such as the identification of the minimally effective blend of volatiles that explains the attraction of carnivores to herbivore-infested plants, and evolutionary aspects such as the fitness consequences of induced volatiles. The elucidation of mechanistic aspects is important for addressing ecological and evolutionary questions. For instance, an important tool to address ecological and evolutionary aspects would be to have plant pairs that differ in only a single trait. Such plants are likely to become available in the near future as a result of mechanistic studies on signal-transduction pathways and an increased interest in molecular genetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004111624780
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  • 4
    Electronic Resource
    Electronic Resource
    The making of a pest: recruitment of Meligethes aeneus onto oilseed Brassicas (2000)
    Springer
    Entomologia experimentalis et applicata 95 (2000), S. 141-149 
    Details
    ISSN: 1570-7458
    Keywords: ecology ; reproductive success ; fecundity ; intraspecific competition ; evolution ; pest outbreaks ; pest control ; chemical control ; economic threshold ; oilseed rape ; turnip rape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Populations of the rapeseed pollen beetle Meligethes aeneus F. (Col., Nitidulidae) from areas with 0–16 years of history of intensive rapeseed growing were compared for key ecological characters. During the first 16 years of rapeseed cultivation the reproductive success of M. aeneus increased 200–300% over that of the beetles living on the natural host plants, cruciferous weeds. The increase was linear over time and statistically highly significant, and it did not appear to be related to food quality or to the size of the beetles. During the same period the tolerance to intraspecific competition decreased, possibly due to the relative absence of such competition on the new crop. Furthermore, the optimum population density for M. aeneus to maximize the size of its next generation on summer turnip rape was determined to be 0.5–1.0 beetles/plant, which is slightly below the economic threshold for chemical control (1 beetle/plant). Therefore the practical protection of the rapeseed yield also ensures the highest possible pest population size for the next year. These mechanisms may in part explain the particular noxiousness of the species as a pest all over Europe. In general these data show that after the introduction of a new crop plant into a region, significant changes during the recruitment process in a pestiferous insect may take place, contributing to the future pest status of the insect. It is suggested that such genetic and ecological changes in insects may be a more common mechanism than previously thought in initiating and sustaining pest outbreaks, and that conventional pest management methods may enhance that effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003947706788
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  • 5
    Electronic Resource
    Electronic Resource
    Copulatory Courtship in Drosophila: Behavior and Songs of D. birchii and D. serrata (2000)
    Springer
    Journal of insect behavior 13 (2000), S. 71-86 
    Details
    ISSN: 1572-8889
    Keywords: copulatory courtship ; behavioral interactions ; songs ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract D. birchii and D. serrata, two endemic Australian Drosophila species, have a copulatory courtship. The males of these species begin to court the female after mounting her and often go on with the courtship after the copulation is over. In the present paper we have described behavioral interactions between the male and the female and analyzed acoustic signals produced by the flies during courtship. Species differences were more pronounced in female than in male behavior. Variation within the species was obvious in the relative proportions of time the flies spent in different behaviors. Even though courtship took place nearly solely during copulation, some remains of precopulatory courtship were observed in both species. It is suggested that copulatory courtship exhibited by D. birchii and D. serrata flies is a derived rather than a primitive character.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007715609756
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  • 6
    Electronic Resource
    Electronic Resource
    Evolution of Ti–Sn-rutile-supported V2O5–WO3 catalyst during its use in nitric oxide reduction by ammonia (2000)
    Springer
    Topics in catalysis 11-12 (2000), S. 131-138 
    Details
    ISSN: 1572-9028
    Keywords: rutile supported V2O5–WO3 catalyst ; evolution ; NO reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper concerns the relation between surface structure of crystalline vanadia-like active species on vanadia–tungsta catalyst and their activity in the selective reduction of NO by ammonia to nitrogen. The investigations were performed for Ti–Sn-rutile-supported isopropoxy-derived catalyst. The SCR activity and surface species structure were determined for the freshly prepared catalyst, for the catalyst previously used in NO reduction by ammonia (320 ppm NO, 335 ppm NH3 and 2.35 vol% O2) at 573 K as well as for the catalyst previously annealed at 573 K in helium stream containing 2.35 vol% O2. The crystalline islands, exposing main V2O5 surface, with some tungsten atoms substituted for V-ones, were found, with XPS and FT Raman spectroscopy, to be present at the surface of the freshly prepared catalyst. A profound evolution of the active species during the catalyst use at 573 K was observed. Dissociative water adsorption on V5+OW6+ sites is discussed as mainly responsible for the catalyst activity at 473 K and that on both V5+OW6+ and V4+OW6+ sites as determining the activity at 523 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1027299931119
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  • 7
    Electronic Resource
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    Experience, Awareness and Consciousness:Suggestions for Definitions as Offered by an Evolutionary Approach (2000)
    Springer
    Foundations of science 5 (2000), S. 429-456 
    Details
    ISSN: 1572-8471
    Keywords: awareness ; reflexive awareness and consciousness ; evolution ; experience and pattern matching ; symbolic language
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General
    Notes: Abstract An evolutionary point of view is proposed to make more appropriate distinctions between experience, awareness and consciousness. Experience can be defined as a characteristic linked closely to specific pattern matching, a characteristic already apparent at the molecular level at least. Awareness can be regarded as the special experience of one or more central, final modules in the animal neuronal brain. Awareness is what experience is to animals. Finally, consciousness could be defined as reflexive awareness. The ability for reflexive awareness is distinctly different from animal and human awareness and depends upon the availability of a separate frame of reference, as provided by symbolic language. As such, words have made reflexive awareness – a specific and infrequent form of awareness – possible. Conciousness might be defined as the experience evoked by considering, i.e. thinking about experiences themselves. If there is a hard problem of explaining consciousness, than this actually must be considered as the hard problem already met when trying to explain basic experience, since its nature remains elusive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011371811027
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  • 8
    Electronic Resource
    Electronic Resource
    Arbitrariness in nature: synergetics and evolutionary laws of prohibition (2000)
    Springer
    Journal for general philosophy of science 31 (2000), S. 57-73 
    Details
    ISSN: 1572-8587
    Keywords: complex systems ; evolution ; nonlinearity ; pre-determination ; self-organization ; soft management ; structure-attractors ; synergetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Philosophy , Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract The philosophical consequences of synergetics, the interdisciplinary theory of evolution and self-organization of complex systems, are being drawn in the paper. The idea of discreteness of evolutionary paths is in the focus of attention. Although the future is open, and there are many alternative evolutionary paths for complex systems, not any arbitrary (either conceivable or desirable) evolutionary path is feasible in a given system. There are discrete spectra of possible evolutionary paths which are determined exclusively by inner properties of the corresponding systems. Synergetics allows us to reveal general laws of self-organization and, therefore, certain limits of arbitrariness of nature in choosing possible paths of evolution as well as in constructing of a complex evolutionary whole. A comparative analysis between the modern synergetic notions and a few ideas of the Western philosophy (F. Nietzsche, N. Hartmann, M. Heidegger) and of the Eastern teachings (Taoism, Buddhism) is made.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008369525041
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  • 9
    Electronic Resource
    Electronic Resource
    Morality De-Kanted or the Biological Roots of Moral Behavior (2000)
    Springer
    International journal of value-based management 13 (2000), S. 297-308 
    Details
    ISSN: 1572-8528
    Keywords: morality ; moral systems ; behavior ; evolution ; adaptation ; natural selection ; altruism ; reciprocal altruism ; fitness ; reciprocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract The ethical and moral behavior of Homo sapiens is no longer the exclusive domain of religion and philosophy because we recognize that such behavior affects the reproductive success of individuals within the species. We are a social species and therefore our survival is influenced by our capacity for cooperation and our willingness to take risks for kin. Emotions, some of which are found in other species, help to mediate our altruistic behavior. The reproductive benefits of helping kin, especially offspring, are readily seen. Helping non-kin can be beneficial if individuals can differentiate between ‘reciprocators’ and ‘non-reciprocators’ and direct altruistic behavior toward reciprocators. Also, if third parties are favorably impressed by observing altruistic behavior, the rewards need not come from the recipient of the altruistic behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007897311267
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  • 10
    Electronic Resource
    Electronic Resource
    A survey of equid mitochondrial DNA: Implications for the evolution, genetic diversity and conservation of Equus (2000)
    Springer
    Conservation genetics 1 (2000), S. 341-355 
    Details
    ISSN: 1572-9737
    Keywords: conservation genetics ; Equus ; evolution ; mitochondrial DNA control region ; mitochondrial 12S rRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolution, taxonomy and conservation of the genus Equuswere investigated by examining the mitochondrial DNA sequences of thecontrol region and 12S rRNA gene. The phylogenetic analysis of thesesequences provides further evidence that the deepest node in thephylogeny of the extant species is a divergence between twolineages; one leading to the ancestor of modern horses (E.ferus, domestic and przewalskii) and the other to thezebra and ass ancestor, with the later speciation events of the zebrasand asses occurring either as one or more rapid radiations, or withextensive secondary contact after speciation. Examination of the geneticdiversity within species suggested that two of the E. hemionussubspecies (E. h. onager and E. h. kulan) onlyrecently diverged, and perhaps, are insufficiently different to beclassified as separate subspecies. The genetic divergence betweendomestic and wild forms of E. ferus (horse) and E.africanus (African ass) was no greater than expected within anequid species. In E. burchelli (plains zebra) there was anindication of mtDNA divergence between populations increasing withdistance. The implications of these results for equid conservation arediscussed and recommendations are made for conservation action.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011559200897
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  • 11
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    Last Judgment: The Visionary Biology of J. B. S. Haldane (2000)
    Springer
    Journal of the history of biology 33 (2000), S. 457-491 
    Details
    ISSN: 1573-0387
    Keywords: J. B. S. Haldane ; biology ; politics ; genetics ; evolution ; population genetics ; physiology ; Darwinism ; experimental biology ; eugenics ; Britain ; Russia ; India ; Soviet ; Communism ; socialism ; philosophy ; vision ; literature ; popularization ; religion ; human experimentation ; bioethics ; Venus ; Mars ; science fiction ; technocracy ; futurology ; H. G. Wells ; Julian Huxley ; Olaf Stapledon ; C. S. Lewis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract This paper seeks to reinterpret the life and work of J. B. S. Haldane by focusing on an illuminating but largely ignored essay he published in1927, “The Last Judgment” – the sequel to his better known work, Daedalus (1924). This astonishing essay expresses a vision of the human future over the next 40,000,000 years, one that revises and updates Wellsian futurism with the long range implications of the “new biology” for human destiny. That vision served as a kind of lifelong credo, one that infused and informed his diverse scientific work, political activities, and popular writing, and that gave unity and coherence to his remarkable career.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004891323595
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  • 12
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    Sex, Death, and Evolution in Proto- and Metazoa, 1876–1913 (2000)
    Springer
    Journal of the history of biology 33 (2000), S. 221-246 
    Details
    ISSN: 1573-0387
    Keywords: August Weismann ; ciliates ; Clifford Dobell ; cytology ; death ; Emile Maupas ; evolution ; Herbert Spencer Jennings ; Otto Bütschli ; Paramecium ; rejuvenescence ; sex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract In the period 1875–1920, a debate about the generality and applicability of evolutionary theory to all organisms was motivated by work on unicellular ciliates like Paramecium because of their peculiar nuclear dualism and life cycles. The French cytologist Emile Maupas and the German zoologist August Weismann argued in the 1880s about the evolutionary origins and functions of sex (which in the ciliates is not linked to reproduction), and death (which appeared to be the inevitable fate of lineages denied sexual conjugation), an argument rooted in the question of whether the ciliates and their processes where homologous to other cellular organisms. In the beginning of the twentieth century, this question of homology came to be less important as the ciliates were used by the British protozoologist Clifford Dobell and the American zoologist Herbert Spencer Jennings to study evolutionary processes in general rather than problems of development and cytology. For them, homology mattered less than analogy. This story illustrates two partially distinct problems in evolutionary biology: first, the question of whether all living things have common features and origins; and second, whether their history and current nature can be described by identical mechanisms. Where Maupas (contra Weismann) made the ciliates qualitatively the same as all other organisms in order to create a cohesive evolutionary theory for biology, Jennings and Dobell made them qualitatively different in order to achieve the same end.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004740325150
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  • 13
    Electronic Resource
    Electronic Resource
    Neutralizing antibody provided protection against enterovirus type 71 lethal challenge in neonatal mice (2000)
    Springer
    Journal of biomedical science 7 (2000), S. 523-528 
    Details
    ISSN: 1423-0127
    Keywords: Enterovirus type 71 ; Experimental infection ; Mice ; Neutralizing antibody ; Vaccine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Experimental infection with enterovirus type 71 (EV71) induced death in neonatal mice in an age- and dose-dependent manner. The mortality rate was 100% following intraperitoneal inoculation 1-day-old ICR mice and this gradually decreased as the age at the time of inoculation increased (60% in 3-day-old mice and no deaths occurred in mice older than 6 days of age). A lethal dose greater than 108 PFU was necessary. Lethargy, failure to gain weight, rear limb tremors and paralysis were observed in the infected mice before death. EV71 was isolated from various tissues of the dead mice. Using a reverse transcription polymerase chain reaction technique with a specific primer pair, a 332-bp product was detected in the tissues that produced a culture positive for EV71. Protection against EV71 challenge in neonatal mice was demonstrated following passive transfer of serum from actively immunized adult mice 1 day after inoculation with the virus. Pups from hyperimmune dams were resistant to EV71 challenge. Additionally, maternal immunization with a formalin-inactivated whole-virus vaccine prolonged the survival of pups after EV71 lethal challenge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253368
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  • 14
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    Elasticity of the pyrope (Mg3Al2Si3O12)-majorite (MgSiO3) garnets solid solution (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 445-452 
    Details
    ISSN: 1432-2021
    Keywords: Keywords Garnets ; Polycrystals ; Hot-pressing ; Elasticity ; Interferometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Dense isotropic polycrystalline specimens of majorite-rich garnets (Py100, Py62Mj38, Py50Mj50, Py21Mj79 and Mj100) along the pyrope (Mg3Al2Si3O12 = Py100)-majorite (MgSiO3 = Mj100) join were fabricated in a 2000-ton uniaxial split-sphere anvil apparatus (USSA-2000) at pressures from 10 to 18.5 GPa and temperatures from 1200 to 1850 °C, within their stability fields in runs of 2–4-h duration, using hot-pressing techniques developed by Gwanmesia et al. (1993). These specimens are single-phased, fine-grained (≤5 mm), free of microcracks, and have bulk densities greater than 99% of the corresponding single-crystal X-ray density. Elastic compressional (P) and shear (S) wave velocities were determined at room pressure and temperature for these polycrystalline garnet specimens by phase comparison ultrasonic interferometry. For Mj100, the P and S wave velocities are within 1% of the Hashin-Shtrikman averages calculated from the single crystal elastic moduli measured by Brillouin spectroscopy. Both the elastic bulk modulus (K) and the shear modulus (G) decrease continuously with increasing majorite content from pyrope garnet (Py100) to pure majorite garnet (Mj100). The compositional dependence of K and G are given by K = 172.3 (40) − 0.085X, and G = 91.6 (10) − 0.038X, where X = mol% majorite), respectively, indicating that substitution of Si for Mg and Al decreases both K and G by about 5% along the solid solution series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002699900054
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  • 15
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    Measurement of the elasticity of the actin tail of Listeria monocytogenes (2000)
    Springer
    European biophysics journal 29 (2000), S. 134-140 
    Details
    ISSN: 1432-1017
    Keywords: Key wordsListeria monocytogenes ; Cell motility ; Actin gel ; Elasticity ; Optical tweezers ; Cell mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract We report biophysical experiments performed on the bacterium Listeria monocytogenes, a model system to study actin-based motility. Using optical tweezers and electrophoresis experiments, we find that the bacterium is firmly attached to its tail, and we demonstrate that the tail responds as an elastic gel when deformed. We have measured its elastic modulus at a value of 103–104 Pa, which is 10 times higher than the rigidity of the eukaryotic cytoplasm. These results demonstrate that the bacterium and its tail form a very robust system, consistent with the steadyness of the motion observed in vivo. We propose an elastic model for the propulsion mechanism which takes into account the connection and thus the interaction between the actin filaments. It provides a generic description of the various aspects of actin-tail based movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002490050258
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  • 16
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    Shear circular dislocation loops investigated with elasticity theory and atomistic simulations (2000)
    Springer
    Journal of computer-aided materials design 7 (2000), S. 25-42 
    Details
    ISSN: 1573-4900
    Keywords: Copper ; Dislocation ; Elasticity ; Molecular dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The elastic fields of displacements, strains, and stresses for a shear circular loop are obtained with the Burgers formula. In addition, interactions between two shear circular loops are obtained based on elasticity theory. A series of molecular dynamics (MD) simulations on a shear circular partial dislocation loop in copper have been performed to examine the elastic solutions. It is found that the results of the MD simulations are in good agreement with those of elasticity theory for a loop with radius ∼7.5 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008766500345
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  • 17
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    Complex hypersingular integral equation for the piece-wise homogeneous half-plane with cracks (2000)
    Springer
    International journal of fracture 102 (2000), S. 177-204 
    Details
    ISSN: 1573-2673
    Keywords: Elasticity ; half-plane ; boundary integral equations ; hypersingular.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract New complex hypersingular integral equation (CHSIE) is derived for the half-plane containing the inclusions (which can have the different elastic properties), holes, notches and cracks of the arbitrary shape. This equation is obtained by superposition of the equations for each homogeneous region in a half-plane. The last equations follow from the use of complex analogs of Somigliana's displacement and stress identities (SDI and SSI) and Melan's fundamental solution (FS) written in a complex form. The universal numerical algorithm suggested before for the analogous problem for a piece-wise homogeneous plane is extended on case of a half plane. The unknown functions are approximated by complex Lagrange polynomials of the arbitrary degree. The asymptotics for the displacement discontinuities (DD) at the crack tips are taken into account. Only two types of the boundary elements (straight segments and circular arcs) are used to approximate the boundaries. All the integrals involved in CHSIE are evaluated in a closed form. A wide range of elasticity problems for a half-plane with cracks, openings and inclusions are solved numerically.
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    URL: http://dx.doi.org/10.1023/A:1007633814813
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    Interaction among a row of ellipsoidal inclusions (2000)
    Springer
    International journal of fracture 102 (2000), S. 371-392 
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    ISSN: 1573-2673
    Keywords: Elasticity ; body force method ; singular integral equations ; numerical analysis ; three-dimensional analysis ; stress concentration factor ; ellipsoidal inclusion.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper the interaction among a row of N ellipsoidal inclusions of revolution is considered. Inclusions in a body under both (A) asymmetric uniaxial tension in the x-direction and (B) axisymmetric uniaxial tension in the z-direction are treated in terms of singular integral equations resulting from the body force method. These problems are formulated as a system of singular integral equations with Cauchy-type or logarithmic-type singularities, where unknowns are densities of body forces distributed in the r,θ,z directions. In order to satisfy the boundary conditions along the ellipsoidal boundaries, the unknown functions are approximated by a linear combination of fundamental density functions and polynomials. The present method is found to yield rapidly converging numerical results for interface stresses. When the elastic ratio E 1⇒E I/E M〉1, the primary feature of the interaction is a large compressive or tensile stress σn on the interface θ=0. When E 1⇒E I/E M〈1, a large tensile stress σθ or σt on the interface θ=1/2π is of interest. If the spacing b/d and the elastic ratio E I/E M are fixed, the interaction effects are dominant when the shape ratio a/b is large. For any fixed shape and spacing of inclusions, the maximum stress is shown to be linear with the reciprocal of the squared number of inclusions.
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    URL: http://dx.doi.org/10.1023/A:1007604809440
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    The accumulation of geophysical data in digitized format may give glimpses into the evolution of the Earth (2000)
    Springer
    The environmentalist 20 (2000), S. 257-271 
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    ISSN: 1573-2991
    Keywords: evolution ; tides ; sea level ; time series
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The increasing use of computers since the 1960s, has implied the digitization of observations in meteorology, oceanography and other observational sciences. Enough data has been accumulated to suggest that some patterns of evolution in the world may be discernable. The present article deals with what appears as changing tides around Canada.
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    URL: http://dx.doi.org/10.1023/A:1006712100068
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    Genome Organization and Phylogenetic Distribution of a Novel Family of Ancient Murine Endogenous Proviruses with Evidence for Transposition-Mediated Proliferation (2000)
    Springer
    Biochemical genetics 38 (2000), S. 253-265 
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    ISSN: 1573-4927
    Keywords: ancient endogenous provirus ; evolution ; retrotransposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A new family of murine endogenous proviruses (VL6.0) is described here. The intact provirus is near 6 kb in length and shows a genomic organization of 5" LTR, gag, pol, env, and 3" LTR. The primer binding site (PBS) is that of a tRNAgly. The lack of functional open reading frames and occurrence of significant gaps in most, if not all, members of this group show it to be ancient. Our estimate of copy number per haploid genome is 30+. Members of this group have been isolated from Mus musculus domesticus, M. m. casteneus, M. m. hortulanus, M. caroli, and M. spretus. The occurrence of these sequences throughout such diverse members of the genus Mus may indicate that the date of the original infection predated the divergence of the extant Mus lineages at around 2.5 million years ago. Analysis of gap (deletion/insertion) patterns indicates that these sequences may have proliferated within the Mus genome by a mechanism of reverse transcriptase-mediated transposition. As yet, there are no closely related murine retroviruses described. The closest mammalian retrovirus based on sequence similarity is from the miniature swine (Sus scrofa).
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    A multigene phylogeny of theGibberella fujikuroi species complex: Detection of additional phylogenetically distinct species (2000)
    Springer
    Mycoscience 41 (2000), S. 61-78 
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    ISSN: 1618-2545
    Keywords: biogeography ; calmodulin ; DNA sequence ; elongation factor EF-1α ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phylogenetic relationships within theGibberella fujikuroi species complex were extended to newly discovered strains using nucleotide characters obtained by sequencing polymerase chain reaction (PCR) amplified DNA from 4 loci used in a previous study [nuclear large subunit 28S rDNA, nuclear ribosomal internal transcribed spacer (ITS) region, mitochondriaal small subunit (mtSSU) ribosomal DNA, and β-tubulin] together with two newly sampled protein-encoding nuclear genes, translation elongation factor EF-1α and calmodulin. Sequences from the ribosomal ITS region were analyzed separately and found to contain of two highly divergent, nonorthologous ITS2 types. Phylogenetic analysis of the individual and combined datasets identified 10 new phylogenetically distinct species distributed among the following three areas: 2 within Asia and 4 within both Africa and South America. Hypotheses of the monophyly ofFusarium subglutinans and its two formae speciales, f. sp.pini and f. sp.ananas, were strongly rejected by a likelihood analysis. Maximum parsimony results further indicate that the protein-encoding nuclear genes provide considerably more phylogenetic signal that the ribosomal genes sequenced. Relative apparent synapomorphy analysis was used to detect long-branch attraction taxa and to obtain a statistical measure of phylogenetic signal in the individual and combined datasets.
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    URL: http://dx.doi.org/10.1007/BF02464387
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    Papulosa amerospora accommodated in a new family (papulosaceae, sordariomycetes, ascomycota) inferred from morphological and molecular data (2000)
    Springer
    Mycoscience 41 (2000), S. 97-103 
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    ISSN: 1618-2545
    Keywords: Ascomycota ; evolution ; pyrenomycetes ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To investigate the systematic position of the unitunicate pyremomycetePapulosa amerospora, we performed phylogenetic analyses of SSU rDNA sequences from 37 ascomycetes. Among these sequences were some new ones from taxa that might be related toPapulosa: Hyponectriaceae (Hyponectria buxi, Monographella nivalis), Phyllachorales (Phyllachora graminis), and Xylariales (Barrmaelia melanotes, Poronia punctata). Our results showed 100% bootstrap support for a clade of all unitunicate pyrenomycetes, the class Sordariomycetes. We also found strong support for recognizing the subclasses Hypocreomycetidae and Xylariomycetidae. The remaining taxa, belonging to subclass Sordariomycetidae, appeared as a polyphyletic group in one analysis, but was monophyletic when shorter SSU sequences were used.Barrmaelia melanotes, Poronia punctata, Hyponectria buxi, andMonographella nivalis are members of Xylariomycetidae, but we could not determine whetherMonographella should be included in Hyponectriaceae. The new family Papulosaceae is erected forPapulosa on molecular and morphological bases, but the exact systematic position ofPapulosa within subclass Sordariomycetidae is still uncertain, since the genus did not cluster consistently with any of the included taxa. Phyllachorales are not closely related to Diaporthales, as previously suggested.
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    The joys of HexNAc. The synthesis and function of N-andO-glycan branches (2000)
    Springer
    Glycoconjugate journal 17 (2000), S. 465-483 
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    ISSN: 1573-4986
    Keywords: N-acetylglucosaminyltransferases ; glycosylation ; glycoproteins ; Golgi complex ; evolution ; development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This review covers discoveries made over the past 30–35 years that were important to our understanding of the synthetic pathway required for initiation of the antennae or branches on complex N-glycans and O-glycans. The review deals primarily with the author's contributions but the relevant work of other laboratories is also discussed. The focus of the review is almost entirely on the glycosyltransferases involved in the process. The following topics are discussed. (1) The localization of the synthesis of complex N-glycan antennae to the Golgi apparatus. (2) The “evolutionary boundary” at the stage in N-glycan processing where there is a change from oligomannose to complex N-glycans; this switch correlates with the appearance of multicellular organisms. (3) The discovery of the three enzymes which play a key role in this switch, N-acetylglucosaminyltransferases I and II and mannosidase II. (4) The “yellow brick road” which leads from oligomannose to highly branched complex N-glycans with emphasis on the enzymes involved in the process and the factors which control the routes of synthesis. (5) A short discussion of the characteristics of the enzymes involved and of the genes that encode them. (6) The role of complex N-glycans in mammalian and Caenorhabditis elegans development. (7) The crystal structure of N-acetylglucosaminyltransferase I. (8) The discovery of the enzymes which synthesize O-glycan cores 1, 2, 3 and 4 and their elongation.
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    URL: http://dx.doi.org/10.1023/A:1011010206774
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    Group Selection and the Limits to Altruism (2000)
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    Journal of bioeconomics 2 (2000), S. 9-23 
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    ISSN: 1573-6989
    Keywords: evolution ; altruism ; morality ; utilitarianism ; Marxism ; Rawls ; fairness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Economics
    Notes: Abstract Several evolutionary mechanisms have been identified in the literature that would generate altruism in humans. The most powerful (except for kin selection) and most controversial is group selection, as recently analyzed by Sober & D.S. Wilson. I do not take a stand on the issue of the existence of group selection. Instead, I examine the level of human altruism that could exist if group selection were an engine of human evolution. For the Sober & Wilson mechanism to work, groups practicing altruism must grow faster than other groups. I call altruistic behavior that would lead to faster growth ‘efficient altruism’. This often consists of cooperation in a prisoner's dilemma. ltruistic acts such as helping a temporarily hungry or injured person would qualify as efficient altruism. Efficient altruism would also require monitoring recipients to avoid shirking. Utilitarianism would be an ethical system consistent with efficient altruism, but Marxism or the Rawlsian system would not. Discussions of efficient altruism also help understand intuitions about fairness. We perceive those behaviors as ‘fair’ that are consistent with efficient altruism. It is important to understand that, even if humans are selected to be altruistic, the forms of altruism that might exist must be carefully considered and ircumscribed.
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    Evolutionary Epistemology, Social Epistemology, and the Demic Structure of Science (2000)
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    Biology and philosophy 15 (2000), S. 443-463 
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    ISSN: 1572-8404
    Keywords: David Hull ; evolution ; selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract One of the principal difficulties in assessing Science as aProcess (Hull 1988) is determining the relationship between the various elements of Hull's theory. In particular, it is hard to understand precisely how conceptual selection is related to Hull's account of the social dynamics of science. This essay aims to clarify the relation between these aspects of his theory by examining his discussion of the``demic structure'' of science. I conclude that the social account cando significant explanatory work independently of the selectionistaccount. Further, I maintain that Hull's treatment of the demicstructure of science points us toward an important set of issues insocial epistemology. If my reading of Science as a Process iscorrect, then most of Hull's critics (e.g., those who focus solelyon his account of conceptual selection) have ignored promisingaspects of his theory.
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    Complexity versus Uncertainty: The Question of Staying Alive (2000)
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    Biology and philosophy 15 (2000), S. 493-508 
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    ISSN: 1572-8404
    Keywords: complexity ; entropy balance ; environment independence ; evolution ; information fundamental identity ; uncertainty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Some real objects show a very particular tendency: that of becomingindependent with regard to the uncertainty of their surroundings. This isachieved by the exchange of three quantities: matter, energy andinformation. A conceptual framework, based on both Non-equilibriumThermodynamic and the Mathematical Theory of Communication is proposedin order to review the concept of change in living individuals. Three mainsituations are discussed in this context: passive independence inconnection with resistant living forms (such as seeds, spores, hibernation,...), active independence in connection with the life span of aliving individual (whether an ant or an ant farm), and the newindependence in connection with the general debate of biological evolution.
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    Functional Complexity in Organisms: Parts as Proxies (2000)
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    Biology and philosophy 15 (2000), S. 641-668 
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    ISSN: 1572-8404
    Keywords: complexity ; evolution ; function ; modularity ; parts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract The functional complexity, or the number of functions, of organisms hasfigured prominently in certain theoretical and empirical work inevolutionary biology. Large-scale trends in functional complexity andcorrelations between functional complexity and other variables, such assize, have been proposed. However, the notion of number of functions hasalso been operationally intractable, in that no method has been developedfor counting functions in an organism in a systematic and reliable way.Thus, studies have had to rely on the largely unsupported assumption thatnumber of functions can be measured indirectly, by using number ofmorphological, physiological, and behavioral “parts” as a proxy. Here, amodel is developed that supports this assumption. Specifically, the modelpredicts that few parts will have many functions overlapping in them, andtherefore the variance in number of functions per part will be low. If so,then number of parts is expected to be well correlated with number offunctions, and we can use part counts as proxies for function counts incomparative studies of organisms, even when part counts are low. Alsodiscussed briefly is a strategy for identifying certain kinds of parts inorganisms in a systematic way.
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    URL: http://dx.doi.org/10.1023/A:1006695908715
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    Darwinian Ethics and Error (2000)
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    Biology and philosophy 15 (2000), S. 713-732 
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    ISSN: 1572-8404
    Keywords: Darwin ; error theory ; ethics ; evolution ; evolutionary ethics ; Mackie ; naturalistic fallacy ; Ruse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Suppose that the human tendency to think of certain actions andomissions as morally required – a notion that surely lies at the heart of moral discourse – is a trait that has been naturallyselected for. Many have thought that from this premise we canjustify or vindicate moral concepts. I argue that this is mistaken, and defend Michael Ruse's view that the moreplausible implication is an error theory – the idea thatmorality is an illusion foisted upon us by evolution. Thenaturalistic fallacy is a red herring in this debate,since there is really nothing that counts as a ‘fallacy’ at all. If morality is an illusion, it appears to followthat we should, upon discovering this, abolish moraldiscourse on pain of irrationality. I argue that thisconclusion is too hasty, and that we may be able usefullyto employ a moral discourse, warts and all, withoutbelieving in it.
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    Molecular phylogeny and radiation time of Erysiphales inferred from the nuclear ribosomal DNA sequences (2000)
    Springer
    Mycoscience 41 (2000), S. 437-447 
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    ISSN: 1618-2545
    Keywords: Ascomycota ; evolution ; molecular clock ; plant pathogen ; powdery mildew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phylogenetic relationships of Erysiphales within Ascomycota were inferred from the newly determined sequences of the 18S rDNA and partial sequences of the 28S rDNA including the D1 and D2 regions of 10 Erysiphales taxa. Phylogenetic analyses revealed that the Erysiphales form a distinct clade among ascomycetous fungi suggesting that the Erysiphales diverged from a single ancestral taxon. The Myxotrichaceae of the Onygenales was distantly related to the other onygenalean families and was the sister group to the Erysiphales calde, with which it combined to form a clade. The Erysiphales/Myxotrichaceae clade was also closely related to some discomycetous fungi (Leotiales, Cyttariales and Thelebolaceae) including taxa that form cleistothecial ascomata. The present molecular analyses as well as previously reported morphological observations suggest the possible existence of a novel evolutionary pathway from cleistothecial discomycetous fungi to Erysiphales and Myxotrichaceae. However, since most of these fungi, except for the Erysiphales, are saprophytic on dung and/or plant materials, the questions of how and why an obligate biotroph like the Erysiphales radiated from the saprophytic fungi remain to be addressed. We also estimated the radiation time of the Erysiphales using the 18S rDNA sequences and the two molecular clockes that have been previously reported. The calculation showed that the Erysiphales split from the Myxotrichaceae 190–127 myr ago. Since the radiation time of the Erysiphales does not exceed 230 myr ago, even when allowance is made for the uncertainty of the molecular clocks, it is possible to consider that the Erysiphales evolved after the radiation of angiosperms. The results of our calculation also showed that the first radiation within the Erysiphales (138–92 myr ago) coincided with the date of a major diversification of angiosperms (130–90 myr ago). These results may support our early assumption that the radiation of the Erysiphales coincided with the evolution of angiosperm plants.
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    Online Interactive Neuro-evolution (2000)
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    Neural processing letters 11 (2000), S. 29-38 
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    ISSN: 1573-773X
    Keywords: evolution ; online ; game ; neural ; network ; genetic ; real-time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In standard neuro-evolution, a population of networks is evolved in a task, and the network that best solves the task is found. This network is then fixed and used to solve future instances of the problem. Networks evolved in this way do not handle real-time interaction very well. It is hard to evolve a solution ahead of time that can cope effectively with all the possible environments that might arise in the future and with all the possible ways someone may interact with it. This paper proposes evolving feedforward neural networks online to create agents that improve their performance through real-time interaction. This approach is demonstrated in a game world where neural-network-controlled individuals play against humans. Through evolution, these individuals learn to react to varying opponents while appropriately taking into account conflicting goals. After initial evaluation offline, the population is allowed to evolve online, and its performance improves considerably. The population not only adapts to novel situations brought about by changing strategies in the opponent and the game layout, but it also improves its performance in situations that it has already seen in offline training. This paper will describe an implementation of online evolution and shows that it is a practical method that exceeds the performance of offline evolution alone.
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    URL: http://dx.doi.org/10.1023/A:1009615730125
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    Co-housing in a stable hierarchical group is not aversive for dominant and subordinate individuals (2000)
    Springer
    Neuroscience and behavioral physiology 30 (2000), S. 195-200 
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    ISSN: 1573-899X
    Keywords: Mice ; dominance ; subordinacy ; stress ; aggression ; locomotor activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The behavior of individaals and their responses to external stimuli are controlled by the microsocial environment, which for most mammals is associated with dominant-subordinate relationships. Physiological and behavioral differences between dominant and subordinate individuals may be ‘primary’ (genetically determined) or ‘secondary’ (due to position in the group's hierarchical structure). A series of experiments was conducted to investigate the physiological (pain response threshold), immunological (thymus, spleen weights, primary immune response), and behavioral (motor activity, behavior in a shuttle box test) characteristics of dominant and subordinate individuals in groups of three laboratory mice formed on the basis of linear hierarchy. Assessment of the effects of group conditions was made using a conditioned reflex location preference test. The results showed: 1) there are no statistically significant differences in physiological and behavioral (except for motor activity) parameters between dominant and subordinate mice; 2) co-housing of dominant and subordinate individuals in groups with stable hierarchical relationships was not aversive for them.
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    Phylogenetic Relationships Among Quolls Revisited: The mtDNA Control Region as a Useful Tool (2000)
    Springer
    Journal of mammalian evolution 7 (2000), S. 1-22 
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    ISSN: 1573-7055
    Keywords: Dasyurus ; marsupials ; control region ; mtDNA ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract There has been a great deal of interest in determining phylogenetic relationships within the family Dasyuridae due to the widespread distribution, ecological diversity, and relative plesiomorphy of this taxon within the Australasian marsupial radiation. In the past, it has been extremely problematic to determine the phylogenetic relationships among species within Dasyurus, with numerous studies using both morphological and molecular characters providing different topologies. Here, the mitochondrial DNA (mtDNA) control region is used as a novel set of characters in an attempt to identify relationships among the six closely related extant species. Sequences were obtained from multiple individuals representing all extant species of quolls including, when possible, individuals from different geographical regions. Sequences were analyzed using both parsimony criteria and neighbor-joining methods. Results presented here concur with those of Krajewski et al. (1997) in (1) placing D. geoffroii in a highly supported clade with D. spartacus, (2) resolving a monophyletic group of D. albopunctatus + D. geoffroii + D. spartacus, and (3) placing D. hallucatus as the sister taxon to all other species of quolls. Results also show two highly supported and geographically distinct clades of D. maculatus (Tasmanian and mainland) that do not correspond to the currently used subspecific nomenclature. Preliminary results also indicate that there are different clades among geographic groups of D. hallucatus that warrant further investigation. The mtDNA control region is a highly variable locus and may be used in forensic tests for species identification in this genus.
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    Diversity in the Integrase Coding Domain of a gypsy-like Retrotransposon Among Wild Relatives of Rice in the Oryza officinalis Complex (2000)
    Springer
    Genetica 110 (2000), S. 43-53 
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    ISSN: 1573-6857
    Keywords: evolution ; Oryza ; retrotransposon ; rice ; wild species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Oryza officinalis complex is a genetically diverse, tertiary genepool of rice. We analyzed part of the primary structure of the integrase coding domain (ICD) of a gypsy-like retrotransposon from species of the O. officinalis species complex. PCR was performed with degenerate primers that hybridized to conserved sequences in the integrase genes of gypsy-type retrotransposons, using total DNA from different species of the O. officinalis complex as templates. Cloning and sequencing of the PCR products showed that the amplified fragments are highly homologous to each other (75–90%) and belong to one family of retrotransposons that is related to the previously studied RIRE-2 element from rice. Two main subfamilies of 292 and 351 bp were distinguished. Analysis of primary sequence data supports previous reports that sequence divergence during vertical transmission has been the major influence on the evolution of gypsy-type retrotransposons in Oryza species. Based on sequence data phylogenetic relationships among species of the O. officinalis complex were estimated. The data suggests that O. eichingeri is more closely related to the ancestral species of the complex.
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    Biogeographic and Ecological Forces Responsible for Speciation in Ateles (2000)
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    International journal of primatology 21 (2000), S. 421-444 
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    ISSN: 1573-8604
    Keywords: phylogenetics ; biogeography ; speciation ; Ateles ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used the results of phylogenetic analyses of relationships among spider monkeys (Ateles) based on mitochondrial and nuclear DNA to investigate questions of their evolutionary origins and speciation mechanisms. We employed the concept of a local molecular clock to date nodes of interest (corresponding to hypothesized species and subspecies) in the various phylograms for comparison to hypothesized biogeographical events that might have affected speciation. We considered various mechanisms—Pleistocene refuge formation, riverine barriers, geological fluctuations, and ecological changes associated with these mechanisms—for their contribution to speciation in Ateles. Most speciation among the various species of Ateles occurred during the middle to late Pliocene, suggesting that Pleistocene refuge formation was not a key speciation mechanism. However, it is likely that the genetic structure of populations of Ateles was modified to some extent by refuge formation. Additionally, riverine barriers do not seem to interrupt gene flow significantly among Ateles. No river formed a barrier among species of Ateles, with the exception of the lower Amazon and possibly some of the black-water rivers draining the Guianan highlands. Large-scale geographic changes associated with the continued rise of the eastern and western cordilleras of the northern Andes and associated changes in habitat were the most important causes of speciation in Ateles. The various factors that modify genetic structure in Ateles are important to consider in order to protect endangered primate genera in the Neotropics.
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    Use of Vocal Fingerprinting for Specific Discrimination of Gray (Microcebus murinus) and Rufous Mouse Lemurs (Microcebus rufus) (2000)
    Springer
    International journal of primatology 21 (2000), S. 837-852 
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    ISSN: 1573-8604
    Keywords: vocalization ; sexual advertisement ; predator advertisement ; taxonomy ; evolution ; mouse lemur ; primate ; Madagascar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Advertisement calls are often important noninvasive tools for discriminating cryptic species and for assessing specific diversity and speciation patterns in nature. We investigated the contribution of these calls to uncover specific diversity in nocturnal Malagasy lemurs. We compared sexual advertisement and predator advertisement calls of two mouse lemur species, western gray and eastern rufous mouse lemurs (Microcebus murinus and M. rufus, respectively) living in two contrasting habitats (dry deciduous vs. rain forest), and analyzed them statistically. Both species emitted several highly variable whistle calls in the context of predator-avoidance. Intrapopulation variation was high and overlapped interspecific variation. Sexual advertisement calls, given in the mating context, displayed a totally distinct, species-specific acoustic structure. Whereas gray mouse lemurs produced rapidly multifrequency modulated, long trill calls, rufous mouse lemurs gave slowly frequency-modulated short chirp calls. Our results suggest specific status for gray and rufous mouse lemurs and indicate the importance of predation and social needs in shaping vocal communication.
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    URL: http://dx.doi.org/10.1023/A:1005594625841
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    Evolutionary implications of host—pathogen specificity: the fitness consequences of host life history traits (2000)
    Springer
    Evolutionary ecology 14 (2000), S. 665-692 
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    ISSN: 1573-8477
    Keywords: disease ; evolution ; frequency-dependent selection ; genetic diversity ; life history ; lifespan ; polymorphism ; reproduction rate ; resistance ; specificity ; virulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pathogens and parasites can be strong agents of selection, and often exhibit some degree of genetic specificity for individual host strains. Here we show that this host–pathogen specificity can affect the evolution of host life history traits. All else equal, evolution should select for genes that increase individuals' reproduction rates or lifespans (and thus total reproduction per individual). Using a simple host–pathogen model, we show that when the genetic specificity of pathogen infection is low, host strains with higher reproduction rates or longer lifespans drive slower-reproducing or shorter-lived host strains to extinction, as one would expect. However, when pathogens exhibit specificity for host strains with different life history traits, the evolutionary advantages of these traits can be greatly diminished by pathogen-mediated selection. Given sufficient host–pathogen specificity, pathogen-mediated selection can maintain polymorphism in host traits that are correlated with pathogen resistance traits, despite large intrinsic fitness differences among host strains. These results have two important implications. First, selection on host life history traits will be weaker than expected, whenever host fitness is significantly affected by genotype-specific pathogen attack. Second, where polymorphism in host traits is maintained by pathogen-mediated selection, preserving the genetic diversity of host species may require preserving their pathogens as well.
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    URL: http://dx.doi.org/10.1023/A:1011647526731
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    A phylogenetic analysis of the Illiciaceae based on sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA (2000)
    Springer
    Plant systematics and evolution 223 (2000), S. 81-90 
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    ISSN: 1615-6110
    Keywords: Cladistics ; evolution ; Illiciales ; Illicium ; ITS ; star anise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sequences of the internal transcribed spacers (ITS) of nuclear ribosomal DNA were determined for 15 species ofIllicium (Illiciaceae) to examine phylogenetic relationships. The ITS trees show a major dichotomy between the two North American species (I. floridanum andI. parviflorum) and the remaining east Asian species. This suggests that the existing division between two sections (sect.Illicium and sect.Cymbostemon) ofIllicium based on tepal characters in unnatural. The ITS phylogeny shows congruence with palynology: of the species examined, the three species (I. angustisepalum, I. anisatum andI. fargesii) from sect.Illicium that possess trizonocolpate pollen consistently form a clade, although nesting within a clade consisting of the species of sect.Cymbostemon, which generally have trisyncolpate pollen. The low ITS sequence divergence and the close relationship among east Asian species suggest a recent diversification of this group of species or an unusual slowdown of sequence mutations.
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    URL: http://dx.doi.org/10.1007/BF00985328
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    The evolution of the ribosomal loci in the subgenusLeopoldia of the genusMuscari (Hyacinthaceae) (2000)
    Springer
    Plant systematics and evolution 221 (2000), S. 245-252 
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    ISSN: 1615-6110
    Keywords: In situ hybridization ; evolution ; NOR ; rDNA ; Muscari
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the subgenusLeopoldia of the genusMuscari, M. comosum is an exceptional species because it presents the most asymmetrical karyotype of the group and because its only active NOR is located in the fifth chromosome pair, while in the other species it is located in the first or second chromosome pairs (all the species have 2n = 18 chromosomes). SinceM. comosum has a derived karyotype different from those of the other species of the group, the resulting question is whether, in the first and second chromosome pair of this species, ribosomal cistrons persist. Observations after fluorescence in situ hybridization (FISH) using rDNA probes indicate that there are indeed ribosomal loci in the first and second chromosome pairs of this species, although these loci are inactive with respect to nucleolus organization. The location of rDNA regions in another three species of the same genus (M. atlanticum, M. dionysicum andM. matritensis) provides a basis for examining the significance of these findings in relation to the evolution of the ribosomal loci in this genus. Our observations indicate that in the genusMuscari, the largest sites for rRNA genes are not necessarily active, and, therefore, the activation of these regions is not related to the number of copies but to a specific regulation mechanism.
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    On the level of cooperative behavior in a local-interaction model (2000)
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    Journal of economics 71 (2000), S. 1-30 
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    ISSN: 1617-7134
    Keywords: evolution ; local interaction ; cooperation ; prisoner's dilemma ; Markov processes ; C78
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract We study local interaction within a population located on a connected graph. Subjects engage in several bilateral interactions during each round in a generalized Prisoners' Dilemma (PD). In each round of play one randomly selected player gets the possibility to update the action he plays in this PD. All individuals use the update rule “Win Cooperate, Lose Defect,” a multi-player variant of Tit-for-Tat. Theoretical results on the set of stable states of the associated dynamics are provided for the cases with and without rare mutations. Simulations provide insight into the probability distribution over these stable states. In both cases a rather high probability is assigned to stable states with a moderate level of cooperation implying that dominated strategies are used. Furthermore, the probability of reaching the stable state with Nash equilibrium play is small.
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    URL: http://dx.doi.org/10.1007/BF01227494
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    The promoter of rbcS in a C3 plant (rice) directs organ-specific, light-dependent expression in a C4 plant (maize), but does not confer bundle sheath cell-specific expression (2000)
    Springer
    Plant molecular biology 44 (2000), S. 99-106 
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    ISSN: 1573-5028
    Keywords: evolution ; C4 plant ; maize ; ribulose-bisphosphate carboxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The small subunit of ribulose-bisphosphate carboxylase (Rubisco), encoded by rbcS, is essential for photosynthesis in both C3 and C4 plants, even though the cell specificity of rbcS expression is different between C3 and C4 plants. The C3 rbcS is specifically expressed in mesophyll cells, while the C4 rbcS is expressed in bundle sheath cells, and not mesophyll cells. Two chimeric genes were constructed consisting of the structural gene encoding β-glucuronidase (GUS) controlled by the two promoters from maize (C4) and rice (C3) rbcS genes. These constructs were introduced into a C4 plant, maize. Both chimeric genes were specifically expressed in photosynthetic organs, such as leaf blade, but not in non-photosynthetic organs. The expressions of the genes were also regulated by light. However, the rice promoter drove the GUS activity mainly in mesophyll cells and relatively low in bundle sheath cells, while the maize rbcS promoter induced the activity specifically in bundle sheath cells. These results suggest that the rice promoter contains some cis-acting elements responding in an organ-pecific and light-inducible regulation manner in maize but does not contain element(s) for bundle sheath cell-specific expression, while the maize promoter does contain such element(s). Based on this result, we discuss the similarities and differences between the rice (C3) and maize (C4) rbcS promoter in terms of the evolution of the C4 photosynthetic gene.
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    Glutamine synthetase isoforms in Trientalis europaea: a biochemical and molecular approach (2000)
    Springer
    Plant and soil 221 (2000), S. 39-45 
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    ISSN: 1573-5036
    Keywords: evolution ; glutamine synthetase ; sequences ; subunit composition ; Trientalis europaea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ion-exchange chromatography of extracts from Trientalis europaea L. leaf tissue have been shown to contain two distinct isoforms of glutamine synthetase (GS). However, analysis by Western blotting has shown that the first peak to elute contains a mixture of large and small GS subunits, whilst the second peak is comprised entirely of a smaller subunit. This is contrary to the widespread assumptions concerning plant GS biochemistry. Isolation of intact chloroplasts and subsequent extraction of GS, followed by ion-exchange chromatography, has shown that the first peak to elute contains a large subunit, and the second chloroplastic peak is composed entirely of the small subunit. This smaller subunit may be present due to it being encoded by a separate chloroplastic GS gene, or it may be present as a product of post-translational modification. DNA sequencing has been used to try and determine which of these may be occurring. The three partial DNA sequences (505 nucleotides) we have obtained from T. europaea have been compared with 64 other sequences available on the NCBI database, which have mainly been obtained from crop species. Neighbour joining and parsimony analysis (1000 bootstrap) has shown support (∼30%) for the separation of plant GS from all other phyla. Within the plant phylum, there is total support for the separation of chloroplastic and cytosolic GS (100%), whilst the cytosolic sequences divide further into monocot and dicot species (77% support by NJ). Further subgroups of plants from the same families is also suggested. This is consistent with previous work containing fewer, but longer (∼1000 nucleotides) GS sequences. The addition of GS sequences obtained from wild plant species, such as T. europaea, to the large amount of information already available on the database, will permit a better understanding of the evolution of this important enzyme.
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    Occurrence of C3 and C4 photosynthesis in cotyledons and leaves of Salsola species (Chenopodiaceae) (2000)
    Springer
    Photosynthesis research 63 (2000), S. 69-84 
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    ISSN: 1573-5079
    Keywords: anatomy ; C3 and C4 photosynthesis ; Chenopodiaceae ; cotyledon ; deserts ; evolution ; leaf ; Salsola
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Most species of the genus Salsola (Chenopodiaceae) that have been examined exhibit C4 photosynthesis in leaves. Four Salsola species from Central Asia were investigated in this study to determine the structural and functional relationships in photosynthesis of cotyledons compared to leaves, using anatomical (Kranz versus non-Kranz anatomy, chloroplast ultrastructure) and biochemical (activities of photosynthetic enzymes of the C3 and C4 pathways, 14C labeling of primary photosynthesis products and 13C/12C carbon isotope fractionation) criteria. The species included S. paulsenii from section Salsola, S. richteri from section Coccosalsola, S. laricina from section Caroxylon, and S. gemmascens from section Malpigipila. The results show that all four species have a C4 type of photosynthesis in leaves with a Salsoloid type Kranz anatomy, whereas both C3 and C4 types of photosynthesis were found in cotyledons. S. paulsenii and S. richteri have NADP- (NADP-ME) C4 type biochemistry with Salsoloid Kranz anatomy in both leaves and cotyledons. In S. laricina, both cotyledons and leaves have NAD-malic enzyme (NAD-ME) C4 type photosynthesis; however, while the leaves have Salsoloid type Kranz anatomy, cotyledons have Atriplicoid type Kranz anatomy. In S. gemmascens, cotyledons exhibit C3 type photosynthesis, while leaves perform NAD-ME type photosynthesis. Since the four species studied belong to different Salsola sections, this suggests that differences in photosynthetic types of leaves and cotyledons may be used as a basis or studies of the origin and evolution of C4 photosynthesis in the family Chenopodiaceae.
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    A phenetic analysis of morphological variation in Citrullus lanatus in Namibia (2000)
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    Genetic resources and crop evolution 47 (2000), S. 385-393 
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    ISSN: 1573-5109
    Keywords: Citrullus lanatus ; cluster analysis ; evolution ; morphology ; watermelon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Morphological data recorded from field trials using Citrullus lanatus germplasm collected in Namibia were used to analyse and compare the various morphotypes of this species. The experiment comprised wild types and local landraces as well as commercial cultivars. Cluster analysis supported the indigenous classification system used in Namibia, in which Citrullus types are distinguished based on gross morphology, ecology and usage and grouped into seed, cooking and fresh-eating (watermelon) types. Commercial watermelon cultivars formed a distinct cluster. Wide variation was found within the local types whereas the genetic basis of the commercial type appears to be narrow. The commercial cultivars were most closely related to local watermelon types and more distantly related to the wild types, whereas the cooking melons form an intermediate group.
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    Multifunctions of the upper lip and a ventral reflecting organ in a bioluminescent ostracod Vargula hilgendorfii (Müller, 1890) (2000)
    Springer
    Hydrobiologia 419 (2000), S. 73-82 
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    ISSN: 1573-5117
    Keywords: reflecting organ ; upper lip ; Myodocopa ; chemical cues ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Multifunctions of the upper lip in a bioluminescent myodocopid Vargula hilgendorfii were studied by video observation and histological method. The localization of luciferin and luciferase gland cells within the upper lip was partly successful. Two long protrusions of the upper lip, both of V. hilgendorfii and a non-luminescent species of the same family, immediately anterior to the mouth, were found to show very flexible movement especially while eating, as if smearing on the food surface a secretion from the protrusions (glands), which may support the hypothesized secretion of digestive enzymes from the upper lip. This hypothesis is further supported by the new finding of a pair of ducts which connect the basal part of the upper lip with the posterior digestive duct (stomach). Comparative studies of V. hilgendorfii with several sympatric non-luminescent species of the same family have also revealed that it has a characteristic reflecting organ immediately posterior to the anus. It is a conical small protrusion, as if dangling from the ventral edge of the abdomen at the apex of the cone. It is observable only in live specimens, when the furca, which is located outwardly to the organ, is sufficiently transparent. When illuminated, the reflecting organ reflects the distinct light. The diameter of the mirror (chemical composition provisionally analyzed) is about 6–8% of the carapace length. The organ develops from the very first stage of its ontogeny without reference to sex, which suggests that the function may be related to intraspecific signaling or predatory deterrence.
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    The ontogeny of the cypridid ostracod Eucypris virens (Jurine, 1820) (Crustacea, Ostracoda) (2000)
    Springer
    Hydrobiologia 419 (2000), S. 31-63 
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    ISSN: 1573-5117
    Keywords: morphology ; ontogeny ; Ostracoda ; evolution ; fifth limb ; crustacean phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chaetotaxy (shape, structure and distribution of setae) of appendages and valve allometry during the post embryonic ontogeny of the cyprididine ostracod Eucypris virens are described. It is shown that the basic ontogenetic development of E. virens is very similar to that of other species of the family Cyprididae. During ontogeny, the chaetotaxy shows continual development on all podomeres of the limbs with the exception of the last podomere on the antennulae. The long setae on the exopodite and protopodite of the antennae have a natatory function until the actual natatory setae develop in later instars. Aesthetascs (presumed chemoreceptors) ya and y3 are the first to develop and may have an important function in the first instars. Cyprididae require a pediform limb in the posterior of the body presumably to help them to attach to substrates and this is reflected by the pediform nature of one limb at all times throughout all instars. This study has also shown that the fifth limb is most probably of thoracic origin and hence ostracods have only one pair of maxillae.
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    Preface: Ostracoda and the four pillars of evolutionary wisdom (2000)
    Springer
    Hydrobiologia 419 (2000), S. 7-11 
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    ISSN: 1573-5117
    Keywords: morphology ; palaeontology ; ecology ; genetics ; Ostracoda ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Morphology, palaeontology, genetics and ecology are the main scientific domains contributing theories, concepts and new data to evolutionary biology. Ostracods are potentially very good model organisms for evolutionary studies because they combine an excellent fossil record with a wide extant distribution and, therefore, allow studies on both patterns and processes leading to extant diversity. This preface provides an overview of the 15 contributions to the present volume and concludes that this set of papers supports the claim that ostracod studies are situated in all main evolutionary domains.
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    Phylogenetic implications of the Crustacean nauplius (2000)
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    Hydrobiologia 417 (2000), S. 91-99 
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    ISSN: 1573-5117
    Keywords: evolution ; phylogeny ; larval characters ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The plesiomorphic mode of crustacean development is widely accepted to be via a larva called the nauplius. Extant taxa like the Cephalocarida, Branchiopoda, Ostracoda, Mystacocarida, Copepoda, Cirripedia, Ascothoracida, Facetotecta, Euphausiacea and Penaeidea hatch from an egg as a free-living nauplius. Other crustaceans show an embryonic phase of development suggestive of a naupliar organization. Several features of the nauplius larva have been proposed as diagnostic characters for the Crustacea: a median (nauplius) eye; at least three pairs of head appendages (antennules, antennae, mandibles); a posteriorly directed fold (the labrum) extending over the mouth and a cephalic (nauplius) shield. The relationship between trilobite protaspis with at least four appendages and the crustacean nauplius remains unclear, but reports of a copepod orthonauplius with four appendages are rejected. Swimming is suggested to represent the underived mode of locomotion for the crustacean nauplius, and that naupliar swimming directly results in naupliar feeding which also is underived.
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    The detection of spatial variation in widespread marine species: methods and bias in the analysis of population structure in the crown of thorns starfish (Echinodermata: Asteroidea) (2000)
    Springer
    Hydrobiologia 420 (2000), S. 1-14 
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    ISSN: 1573-5117
    Keywords: population genetics ; evolution ; allozymes ; DNA ; marine genetics ; Acanthaster planci
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The basic assumptions that widespread marine species should show little spatial variation in genetic structure, given their high potential for dispersal on ocean currents, is being questioned. This has taken some time because there are few studies of widespread marine species over oceanic scales, few data sets that have the high density of sampling required for the detection of fine population structure, and there is little incentive to look further if initial analyses suggest the expected result. The interpretation of the population genetic structure of crown-of-thorns starfish (Acanthaster planci) has been found to vary considerably depending on the sample set included in the analyses and on the method of analysis used. Scatter plots of genetic distance or θ, and spatial autocorrelation approaches gave markedly different results ranging from no structure to isolation by distance. Only visual examination of maps of patterns of variation in allele variation first detected that crown-of-thorns starfish occupy large regions with little between population differentiation, but between which there are markedly higher levels of differentiation. These findings highlight the care required in interpreting population structure, particularly where there are few sample points. Many marine species may have population structures where sharp genetic disjunctions, not associated with any obvious environmental boundaries, separate regions of relative genetic homogeneity. Such population structures are very different from those traditionally assumed and are not yet understood. Further advances in understanding the genetic structure of marine species will demand an iterative approach where a greater number of samples are collected over particular regions identified by earlier interpretations.
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    Molecular systematics of sponges (Porifera) (2000)
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    Hydrobiologia 420 (2000), S. 15-27 
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    ISSN: 1573-5117
    Keywords: phylogeny ; evolution ; allozymes ; rDNA ; DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The first application of molecular systematics to sponges was in the 1980s, using allozyme divergence to dis-criminate between conspecific and congeneric sponge populations. Since this time, a fairly large database has been accumulated and, although the first findings seemed to indicate that sponge species were genetically more divergent than those of other marine invertebrates, a recent review of the available dataset indicates that levels of interspecific gene identities in most sponges fall within the normal range found between species of other invertebrates. Nevertheless, some sponge genera have species that are extremely divergent from each other, suggesting a possible polyphyly of these genera. In the 1990s, molecular studies comparing sequences of ribosomal RNA have been used to reappraise the phylogenetic relationships among sponge genera, families, orders and classes. Both the 18S small subunit and the 28S large subunit rRNA genes have been sequenced (41 complete or partial and 75 partial sequences, respectively). Sequences of 18S rRNA show good support for Porifera being true Metazoa, but they are not informative for resolving relationships among genera, families or orders. 28S rRNA domains D1 and D2 appear to be more informative for the terminal nodes and provide resolution for internal topologies in sufficiently closely related species, but the deep nodes between orders or classes cannot be resolved using this molecule. Recently, a more conserved gene, Hsp70, has been used to try to resolve the relationships in the deep nodes. Metazoan monophyly is very well supported. Nevertheless, the divergence between the three classes of Porifera, as well as the divergence between Porifera, Cnidaria and Ctenophora, is not resolved. Research is in progress using other genes such as those of the homeodomain, the tyrosine kinase domain, and those coding for the aggregation factor. For the moment the dataset for these genes is too restricted to resolve the phylogenetic relationships of these phyla. However, whichever the genes, the phylogenies obtained suggest that Porifera could be paraphyletic and that the phylogenetic relationships of most of the families and orders of the Demospongiae have to be reassessed. The Calcarea and Hexactinellida are still to be studied at the molecular level.
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    Barbus tanapelagius, A New Species from Lake Tana (Ethiopia): its Morphology and Ecology (2000)
    Springer
    Environmental biology of fishes 59 (2000), S. 1-9 
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    ISSN: 1573-5133
    Keywords: Cyprinidae ; piscivores ; prey fish ; small barbs ; species flock ; evolution ; speciation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The endemic cyprinid species flock in Lake Tana consists of 15 species of large hexaploid barbs, eight of which are piscivorous. Previously, it was assumed that all piscivores preyed on the same small barb species, Barbus trispilopleura. In this paper we present a description of morphology and ecology of a new abundant small barb species, Barbus tanapelagius sp. nova (holotype RMNH 33731) from Lake Tana, Ethiopia, which appears to be the major prey species for the large pelagic piscivorous barbs. B. tanapelagius differs clearly in morphology from the other 3 small, diploid Barbus species known from Lake Tana, B. trispilopleura Boulenger, 1902, B. humilis Boulenger, 1902 and B. pleurogramma Boulenger, 1902. Conspicuous differences are its elongated body, large eye diameter, prominent and hooked lower jaw contour and colouration. Preliminary data suggest that B. tanapelagius also differs ecologically from the other small Barbus spp. by its pelagic, strictly zooplanktivorous feeding and its occurrence mainly in the deeper, offshore waters. The other small Barbus species are most probably largely benthic feeders and dominant in the shallow inshore waters. Previous views about the evolution of the present 8 endemic piscivorous large barb species therefore require reconsideration, as the present paper shows a more complex scenario including several prey species.
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    An overview of marine fish cytogenetics (2000)
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    Hydrobiologia 420 (2000), S. 55-62 
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    ISSN: 1573-5117
    Keywords: chromosomes ; evolution ; nucleolar organizer region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The number of cytogenetic studies of marine fish has increased in recent years. Fish groups, such as Perciformes, which comprises many of the extant marine teleosts of economic importance, show little divergence in chromosome number and most species display a diploid number of 48 acrocentric chromosomes. In the Serranidae, Sparidae, Sciaenidae (Perciformes) and Mugilidae (Mugiliformes) small chromosome variations are restricted to subtle heterochromatin or nucleolar organizer region (NOR) modifications. There appears to exist a strict relationship between both absence of geographic barriers throughout the marine environment and high mobility of these animals (eggs, larvae, or adults), with a rarity of chromosome rearrangement at the macrostructural level. Moreover, a cellular homeostasis might also be important to karyotype maintenance among these fishes, limiting changes in the chromosome complement to cryptic chromosome rearrangements. Other groups, such as Blenniidae, Gobiidae and Scorpaenidae, for instance, show more extensive chromosome diversity, which is probably related to limited mobility. Numerical and structural chromosome polymorphisms and several sexual chromosome systems are recurrent among these fishes. A wide karyotypic diversification also characterizes the Tetraodontiformes, an interesting fish group with peculiar morphological, physiological and ecological characteristics.
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    Does Parental Fin Digging Improve Feeding Opportunities for Offspring in the Convict Cichlid? (2000)
    Springer
    Environmental biology of fishes 57 (2000), S. 443-449 
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    ISSN: 1573-5133
    Keywords: parental care ; feeding behaviour ; evolution ; trade-off ; individual differences ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The function of the fin digging behaviour in increasing food availability for the offspring was analysed in the convict cichlid, Cichlasoma (Archocentrus) nigrofasciatum. Consistent individual differences in the frequency of fin digging were found in the parental fish. Examination of the gastrointestinal tract of young revealed that higher frequency of parental fin digging was associated with higher consumption of large and more profitable prey (Diptera larvae), which inhabited deep horizons of the bottom substrate and possibly were difficult to access without parental assistance. Thus, parental fin digging was initially associated with a significant increase of the offspring growth rate. However, at later brood intervals, when parental care ceased, the young of the high-digging parents were characterised by a poorer consumption of small larvae that were most accessible for them without parental aid and represented an increasingly more important component of their ration than large larvae. Offspring of the low-digging parents, on the other hand, presumably as a result of their individual experience, showed a considerably better consumption of small larvae, increasing their growth rate. As a consequence, prior parental fin digging did not affect the offspring body size after independence. Thus, there exist pronounced individual differences and alternative parental styles in the convict cichlid.
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    URL: http://dx.doi.org/10.1023/A:1007654729430
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    Knots in the family tree: evolutionary relationships and functions of knox homeobox genes (2000)
    Springer
    Plant molecular biology 42 (2000), S. 151-166 
    Details
    ISSN: 1573-5028
    Keywords: evolution ; homeodomain protein ; knox gene ; meristem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Knotted-like homeobox (knox) genes constitute a gene family in plants. Class I knox genes are expressed in shoot apical meristems, and (with notable exceptions) not in lateral organ primordia. Class II genes have more diverse expression patterns. Loss and gain of function mutations indicate that knox genes are important regulators of meristem function. Gene duplication has contributed to the evolution of families of homeodomain proteins in metazoans. We believe that similar mechanisms have contributed to the diversity of knox gene function in plants. Knox genes may have contributed to the evolution of compound leaves in tomato and could be involved in the evolution of morphological traits in other species. Alterations in cis-regulatory regions in some knox genes correlate with novel patterns of gene expression and distinctive morphologies. Preliminary data from the analysis of class I knox gene expression illustrates the evolution of complex patterns of knox expression is likely to have occurred through loss and gain of domains of gene expression.
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    URL: http://dx.doi.org/10.1023/A:1006384122567
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    A short history of MADS-box genes in plants (2000)
    Springer
    Plant molecular biology 42 (2000), S. 115-149 
    Details
    ISSN: 1573-5028
    Keywords: angiosperm ; development ; evolution ; fern ; gymnosperm ; MADS-box gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evolutionary developmental genetics (evodevotics) is a novel scientific endeavor which assumes that changes in developmental control genes are a major aspect of evolutionary changes in morphology. Understanding the phylogeny of developmental control genes may thus help us to understand the evolution of plant and animal form. The principles of evodevotics are exemplified by outlining the role of MADS-box genes in the evolution of plant reproductive structures. In extant eudicotyledonous flowering plants, MADS-box genes act as homeotic selector genes determining floral organ identity and as floral meristem identity genes. By reviewing current knowledge about MADS-box genes in ferns, gymnosperms and different types of angiosperms, we demonstrate that the phylogeny of MADS-box genes was strongly correlated with the origin and evolution of plant reproductive structures such as ovules and flowers. It seems likely, therefore, that changes in MADS-box gene structure, expression and function have been a major cause for innovations in reproductive development during land plant evolution, such as seed, flower and fruit formation.
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    URL: http://dx.doi.org/10.1023/A:1006332105728
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    The evolution of nodulation (2000)
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    Plant molecular biology 42 (2000), S. 181-194 
    Details
    ISSN: 1573-5028
    Keywords: actinorhiza ; endomycorrhizae ; evolution ; Frankia ; haemoglobins ; nod factors ; nodulation ; phylogeny ; rhizobia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this review we will first describe the different steps leading to nodule formation, and these will be compared with processes of non-symbiotic plant development and growth. In general, aspects of both actinorhizal as well as rhizobial symbiosis are described, but in several cases, the emphasis will be on the Rhizobium-legume symbiosis because more knowledge of this system is available. Subsequently, the phylogeny of nodulating plants is described and a comparison is made between several aspects of legume and actinorhizal nodulation. At the end of this paper the relationship between nodule symbiosis and endomycorrhizal symbiosis is described, and it is discussed to what extent the development of root nodules involves unique properties, or whether processes and genes have been recruited from common plant development and the endomycorrhizal symbiosis.
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    URL: http://dx.doi.org/10.1023/A:1006396525292
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    Quaternary Structure of Nucleoside Diphosphate Kinases (2000)
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    Journal of bioenergetics and biomembranes 32 (2000), S. 227-236 
    Details
    ISSN: 1573-6881
    Keywords: NDP kinase ; subunit interaction ; quaternary structure ; evolution ; mixed oligomers ; Dictyostelium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Nucleoside (NDP) diphosphate kinases are oligomeric enzymes. Most are hexameric, but somebacterial enzymes are tetrameric. Hexamers and tetramers are constructed by assemblingidentical dimers. The hexameric structure is important for protein stability, as demonstratedby studies with natural mutants (the Killer-of-prune mutant ofDrosophila NDP kinase andthe S120G mutant of the human NDP kinase A in neuroblastomas) and with mutants obtainedby site-directed mutagenesis. It is also essential for enzymic activity. The function of the tetrameric structure is unclear.
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    URL: http://dx.doi.org/10.1023/A:1005580828141
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    Ty1-copia-retrotransposon Behavior in a Polyploid Cotton (2000)
    Springer
    Chromosome research 8 (2000), S. 73-76 
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    ISSN: 1573-6849
    Keywords: evolution ; genome ; Gossypium ; polyploidization ; repetitive element ; retrotransposon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Retrotransposons constitute a ubiquitous and dynamic component of plant genomes. Intragenomic and intergenomic comparisons of related genomes offer potential insights into retrotransposon behavior and genomic effects. Here, we have used fluorescent in-situ hybridization to determine the chromosomal distributions of a Ty1-copia-like retrotransposon in the cotton AD-genome tetraploid Gossypium hirsutum and closely related putative A- and D-genome diploid ancestors. Retrotransposon clone A108 hybridized to all G. hirsutum chromosomes, approximately equal in intensity in the A- and D-subgenomes. Similar results were obtained by hybridization of A108 to the A-genome diploid G. arboreum, whereas no signal was detected on chromosomes of the D-genome diploid G. raimondii. The significance and potential causes of these observations are discussed.
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    URL: http://dx.doi.org/10.1023/A:1009239522541
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    Common Mechanisms of Y Chromosome Evolution (2000)
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    Genetica 109 (2000), S. 105-111 
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    ISSN: 1573-6857
    Keywords: Drosophila ; evolution ; heterochromatin ; Y chromosome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Y chromosome evolution is characterized by the expansion of genetic inertness along the Y chromosome and changes in the chromosome structure, especially the tendency of becoming heterochromatic. It is generally assumed that the sex chromosome pair has developed from a pair of homologues. In an evolutionary process the proto-Y-chromosome, with a very short differential segment, develops in its final stage into a completely heterochromatic and to a great extends genetically eroded Y chromosome. The constraints evolving the Y chromosome have been the objects of speculation since the discovery of sex chromosomes. Several models have been suggested. We use the exceptional situation of the in Drosophila mirandato analyze the molecular process in progress involved in Y chromosome evolution. We suggest that the first steps in the switch from a euchromatic proto-Y-chromosome into a completely heterochromatic Y chromosome are driven by the accumulation of transposable elements, especially retrotransposons inserted along the evolving nonrecombining part of the Y chromosome. In this evolutionary process trapping and accumulation of retrotransposons on the proto-Y-chromosome should lead to conformational changes that are responsible for successive silencing of euchromatic genes, both intact or already mutated ones and eventually transform functionally euchromatic domains into genetically inert heterochromatin. Accumulation of further mutations, deletions, and duplications followed by the evolution and expansion of tandem repetitive sequence motifs of high copy number (satellite sequences) together with a few vital genes for male fertility will then represent the final state of the degenerated Y chromosome.
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    URL: http://dx.doi.org/10.1023/A:1026584016524
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    A Note on Elasticity and Price Dispersions in the Music Recording Industry (2000)
    Springer
    Review of industrial organization 17 (2000), S. 465-470 
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    ISSN: 1573-7160
    Keywords: Elasticity ; music recording industry ; oligopoly ; price dispersions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract The present note examines price dispersions inthe music recording industry between new release andmid-line (older) recordings. The model employs theframework developed within the industrial economicsliterature and provides empirical results suggestingthat new release prices are lower than those ofmid-level recordings. This result follows fromdiffering buyer characteristics and varying levelsof close substitutes, leading to higher demandelasticities for new release recordings. Finally,the theoretical expectations should hold in thepresence of either significant scale economies ormodest minimum efficient scales of production.
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    URL: http://dx.doi.org/10.1023/A:1007820616596
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    Reciprocal chromosome painting illuminates the history of genome evolution of the domestic cat, dog and human (2000)
    Springer
    Chromosome research 8 (2000), S. 393-404 
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    ISSN: 1573-6849
    Keywords: cat ; chromosome painting ; comparative mapping ; dog ; evolution ; human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Domestic cats and dogs are important companion animals and model animals in biomedical research. The cat has a highly conserved karyotype, closely resembling the ancestral karyotype of mammals, while the dog has one of the most extensively rearranged mammalian karyotypes investigated so far. We have constructed the first detailed comparative chromosome map of the domestic dog and cat by reciprocal chromosome painting. Dog paints specific for the 38 autosomes and the X chromosomes delineated 68 conserved chromosomal segments in the cat, while reverse painting of cat probes onto red fox and dog chromosomes revealed 65 conserved segments. Most conserved segments on cat chromosomes also show a high degree of conservation in G-banding patterns compared with their canine counterparts. At least 47 chromosomal fissions (breaks), 25 fusions and one inversion are needed to convert the cat karyotype to that of the dog, confirming that extensive chromosome rearrangements differentiate the karyotypes of the cat and dog. Comparative analysis of the distribution patterns of conserved segments defined by dog paints on cat and human chromosomes has refined the human/cat comparative genome map and, most importantly, has revealed 15 cryptic inversions in seven large chromosomal regions of conserved synteny between humans and cats.
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    URL: http://dx.doi.org/10.1023/A:1009210803123
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    Plant Secondary Compounds and Grasshoppers: Beyond Plant Defenses (2000)
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    Journal of chemical ecology 26 (2000), S. 1773-1794 
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    ISSN: 1573-1561
    Keywords: Grasshoppers ; polyphagy ; graminivory ; evolution ; secondary compound ; peritrophic envelope ; midgut ceca ; learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Modern grasshoppers probably evolved from polyphagous ancestors endowed with the ability to tolerate many plant secondary compounds. This tolerance involves various behavioral and anatomical adaptations. Polyphagous grasshoppers have a relatively low level of sensitivity to the taste of many secondary compounds, and, if they do respond to the taste, have the capacity to habituate. This gives time for the induction of detoxifying enzymes so that unpalatable but potentially nutritious plants may be eaten safely. Associative learning involving secondary compounds may be important in food aversion learning, enabling the insects to avoid foods that have inappropriate nutrients, for example. Learning is also involved when grasshoppers develop associations between the taste of chemicals in the surface waxes of plants and internal leaf chemistry, enabling them to make faster decisions about the acceptability of a plant. Anatomically, the midgut ceca of polyphagous grasshoppers have well-developed posterior arms, and it is possible that these are especially important in detoxification, while some species, in addition, have a specialized pocket region in which macromolecules accumulate to be eliminated from the body when the lining of peritrophic envelope is drawn out. Polyphagous species also have thick peritrophic envelopes to which various phenolics become adsorbed. Finally, the midgut environment contains surfactants that reduce tannin–protein complexing except at very high tannin concentrations. Some polyphagous species can utilize secondary compounds as defensive substances or, in one case, in cuticular sclerotization. Grass feeding has evolved on numerous occasions from these polyphagous ancestors, and it has been associated with a loss of many of the characters providing protection from secondary compounds.
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    A System of Two Polymerases – A Model for the Origin of Life (2000)
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    Origins of life and evolution of the biospheres 30 (2000), S. 459-466 
    Details
    ISSN: 1573-0875
    Keywords: biogenesis ; biological ; coevolution ; evolution ; models ; origin of life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract What was the first living molecule – RNA or protein?This question embodies the major disagreement instudies on the origin of life. The fact that incontemporary cells RNA polymerase is a protein andpeptidyl transferase consists of RNA suggests theexistence of a mutual catalytic dependence betweenthese two kinds of biopolymers. I suggest that thisdependence is a `frozen accident', a remnant from thefirst living system. This system is proposed to be acombination of an RNA molecule capable of catalyzingamino acid polymerization and the resulting proteinfunctioning as an RNA-dependent RNA polymerase. Thespecificity of the protein synthesis is thought to beachieved by the composition of the surrounding mediumand the specificity of the RNA synthesis – by Watson– Crick base pairing. Despite its apparent simplicity,the system possesses a great potential to evolve intoa primitive ribosome and further to life, as it isseen today. This model provides a possible explanationfor the origin of the interaction between nucleicacids and protein. Based on the suggested system, Ipropose a new definition of life as a system ofnucleic acid and protein polymerases with a constantsupply of monomers, energy and protection.
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    Rheological properties of fresh and cryopreserved human arteries tested in vitro (2000)
    Springer
    Rheologica acta 39 (2000), S. 461-468 
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    ISSN: 1435-1528
    Keywords: Key words In vitro tests ; Elasticity ; Human artery ; Cryopreservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Cryopreservation is widely used to preserve blood vessels for a while but is controversially suspected to affect the mechanical behavior of these allografts. The aim of this study was to determine whether differences in the three-dimensional mechanical behavior exist or not between fresh and cryopreserved arteries. Using a previously developed experimental system, in vitro inflation tests were performed on twenty segments of human fresh and cryopreserved arteries, in static conditions. Opening angles were also measured from images of rings in zero-stress state. The initial reference state was chosen as the unloaded state and tests were performed on specimens stretched at natural “in vivo” length. Mechanical measures calculated are “natural” (Hencky) strains (finite deformations), “true” (Cauchy) stresses in radial, circumferential, and longitudinal directions as well as strain energy per unit volume. Tangent moduli are derived from radial and circumferential stress-strain characteristics using non-linear curve fitting. Values of incremental and pressure-strain elastic parameters, wall stiffness, and compliance per unit length are also calculated. Results are presented in terms of characteristics of stresses and strains in the three directions, axial force, tangent moduli vs strains or stresses, and energy per unit volume, for both types of artery, with reference to transmural pressure. Detailed numerical results are given at mean transmural pressure or in the physiological range. Significant differences are indicated by statistic Student T-tests. Results obtained show that significant differences exist between rheological properties of fresh and cryopreserved segments of human artery. Strains, stresses, axial force, strain energy, and wall stiffness values highlight those differences whereas elastic parameters, compliance, and opening angle do not. The usefulness of some parameters to compare the mechanical behavior existing between fresh and cryopreserved arteries is therefore underlined.
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    URL: http://dx.doi.org/10.1007/s003970000110
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    Application of a new separation analyzer for the characterization of dispersions stabilized with clay derivatives (2000)
    Springer
    Colloid & polymer science 278 (2000), S. 369-374 
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    ISSN: 1435-1536
    Keywords: Key words Separation analyzer ; Organoclay dispersions ; Elasticity ; Emulsion stability ; Emulsions stabilized by clay derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The performance of a newly developed separation analyzer is demonstrated by characterization of the sedimentation kinetics and the swelling behavior of organoclays in binary solvent mixtures (toluene/cyclohexane) as well as by investigation of oil-in-water and water-in-oil emulsions stabilized by clay derivatives. The automatic measuring system – LUMiFuge 114 – is based on a special centrifuge with an integrated optoelectronic sensor system which allows the measuring of spatial and temporal changes of light transmission during the rotation in a variable centrifugal field (12–1200g). By using the new device a fast and reproducible characterization of settling behavior and dispersion stability was possible. Moreover, the evaluation of the long-term stability of samples with high separation stability as well as of the heterogenity of the separation process, the sample transparency and the elasticity of the sediment as a function of alternating centrifugal force could be carried out.
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    Phylogenetic analysis of newly described Neosartorya species (2000)
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    Antonie van Leeuwenhoek 77 (2000), S. 235-239 
    Details
    ISSN: 1572-9699
    Keywords: Aspergillus section Fumigati ; β-tubulin gene ; evolution ; phylogenetic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isolates representing newly described Neosartorya species, and isolates with abnormal morphologies from Aspergillus section Fumigati were examined by phylogenetic analysis of sequences of part of their β-tubulin gene. Phylogenetic analyses supported the earlier suggestions that heterothallism is a derived character, and that sexuality was lost several times during the evolution of Aspergillus section Fumigati. The heterothallic N. fennelliae and N. udagawae strains were found to be closely related to the homothallic Neosartorya sp. NRRL 4179 and N. aureola, respectively. Aspergillus sp. FRR 1266, which was earlier described as a variant of A. fumigatus, was found to be closely related to A. viridinutans. Another abnormal asexual isolate was found to be closely related to A. fumigatus and N. fischeri. Phylogenetic relationships among newly described Neosartorya species and other taxa were successfully established based on phylogenetic analysis of β-tubulin sequences.
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    Characterization of the Porphyridium cruentum Chl a-binding LHC by in vitro reconstitution: LHCaR1 binds 8 Chl a molecules and proportionately more carotenoids than CAB proteins (2000)
    Springer
    Photosynthesis research 63 (2000), S. 85-96 
    Details
    ISSN: 1573-5079
    Keywords: chlorophyll a ; Chl a-binding protein ; evolution ; light-harvesting complex ; LHC I ; Porphyridium cruentum ; reconstitution ; red alga ; zeaxanthin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Porphyridium cruentum light harvesting complex (LHC) binds Chl a, zeaxanthin and β-carotene and comprises at least 6 polypeptides of a multigene family. We describe the first in vitro reconstitution of a red algal light-harvesting protein (LHCaR1) with Chl a/carotenoid extracts from P. cruentum. The reconstituted pigment complex (rLHCaR1) is spectrally similar to the native LHC I, with an absorption maximum at 670 nm, a 77 K fluorescence emission peak at 677 nm (ex. 440 nm), and similar circular dichroism spectra. Molar ratios of 4.0 zeaxanthin, 0.3 β-carotene and 8.2 Chl a per polypeptide for rLHCaR1 are similar to those of the native LHC I complex (3.1 zeaxanthin, 0.5 β-carotene, 8.5 Chl a). The binding of 8 Chl a molecules per apoprotein is consistent with 8 putative Chl-binding sites in the predicted transmembrane helices of LHCaR1. Two of the putative Chl a binding sites (helix 2) in LHCaR1 were assigned to Chl b in Chl a/b-binding (CAB) LHC II [Kühlbrandt et al. (1994) Nature 367: 614–21]. This suggests either that discrimination for binding of Chl a or Chl b is not very specific at these sites or that specificity of binding sites evolved separately in CAB proteins. LHCaR1 can be reconstituted with varying ratios of carotenoids, consistent with our previous observation that the carotenoid to Chl ratio is substantially higher in P. cruentum grown under high irradiance. Also notable is that zeaxanthin does not act as an accessory light-harvesting pigment, even though it is highly likely that it occupies the position assigned to lutein in the CAB LHCs.
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    Population diversity of the Vicia sativa agg. (Fabaceae) in the flora of the former USSR deduced from RAPD and seed protein analyses (2000)
    Springer
    Genetic resources and crop evolution 47 (2000), S. 171-183 
    Details
    ISSN: 1573-5109
    Keywords: evolution ; genetic resources ; RAPDs ; seed protein electrophoresis ; taxonomy ; Vicia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The genetic diversity of 58 wild and weedy populations representing taxa within the V. sativa aggregate from the former USSR, 4 cultivars of V. sativa, 2 accessions of V. cordata and 3 accessions of V. macrocarpa from Mediterranean countries were analysed using randomly amplified DNA fragments (RAPDs) and seed protein electrophoresis (SDS-PAGE). Interspecific variation between taxa in the V. sativa aggregate could readily be detected using both techniques. RAPDs and seed protein patterns were found to be an effective means of identifying accessions that cannot be identified clearly by morphological criteria alone. RAPD and seed protein analysis revealed a clear relationship between observed genetic variation of populations and their geographical distribution. Populations from each region had their own gene pools. Geographical variation was detected in V. segetalis. The degree of genetic divergence between local populations was usually related to proximity. In several locations where wild and weedy populations of different V. sativa agg. taxa grow sympatrically, intermediate forms could be detected at the DNA and protein levels. Both RAPD and seed protein analysis support the view that the V. sativa aggregate consists of 8 taxa warranting recognition at the species level. Several species in this aggregate are evolving intra-specific groups which can readily be detected at the molecular level.
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    Application of individual growth and population models of Daphnia pulex to Daphnia magna, Daphnia galeata and Bosmina longirostris (2000)
    Springer
    Hydrobiologia 421 (2000), S. 141-155 
    Details
    ISSN: 1573-5117
    Keywords: cladocerans ; life history ; demography ; size structure ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Daphnia models for individual growth and population dynamics have been developed in the manner of models developed by Gurney, McCauley, Andersen and others. All or most of the earlier models were parameterized for Daphnia pulex; we have used the D. pulex model as a baseline model for other species of Daphnia such as magna, galeata and also Bosmina longirostris. Because of the lack of ample data for D. magna, D. galeata and B. longirostris, some of the physiological data had to be relied on the other species whose data were available and in some case calibrated. We were able to produce reasonable results for individual growth as well as population dynamics under the controlled laboratory conditions. Most of the results were compared with the available laboratory data for population as well as growth. All the simulations have been done under high and low food concentrations. The animals are assumed to be feeding on green algae (Chlamydomonas reinhardtti) under the laboratory conditions of 18–20°C. The continuous growth until the end of the life was observed in smaller B. longirostris, whereas rapid growth in the beginning and slower after the start of the reproduction was observed in Daphnia species. The smaller species matured earlier than larger species. B. longirostris population sustained better than Daphnia species in medium food concentrations.
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    Alu Elements and the Human Genome (2000)
    Springer
    Genetica 108 (2000), S. 57-72 
    Details
    ISSN: 1573-6857
    Keywords: Alu ; evolution ; human specific ; polymorphism ; retroposition ; SINES ; 7SL RNA ; YAP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aluinsertional elements, the most abundant class of SINEs in humans are dimeric sequences approximately 300 bp in length derived from the 7SL RNA gene. These sequences contain a bipartite RNA pol III promoter, a central poly A tract, a 3′ poly A tail, numerous CpG islands and are bracketed by short direct repeats. An estimated 500,000 to 1 × 106units are dispersed throughout the human haploid genome primarily in AT rich neighborhoods located within larger GC dense chromosomal regions via a mechanism known as retroposition. Retroposition activity of Aluelements is determined by both internal and flanking regulatory elements as well as distant genes affecting transcription or transcript stability. Aluelements impact the organization and expression of the human genome at many levels including the processes of recombination, transcription and translation. Twelve subfamilies of Aluare defined by distinct patterns of diagnostic base substitutions. Subfamilies may be classified as young, intermediate or old reflecting the time since the start of retroposition by their members. Some insertions of the youngest subfamilies are not yet fixed in the human species and represent polymorphic loci. Alus are excellent molecular markers for a variety of reasons. They aid in tracing the complex pattern of duplication and rearrangements that occurred during the evolution of primate genome. Unlike other mutations, Alusequences are rarely lost completely once retroposed, have a defined ancestral state and are free from homoplasy since independent and identical insertions are highly unlikely. Because of these characteristics, Alus are literally molecular fossils. Polymorphic Aluloci are especially useful in studies of human genetic diversity and in pedigree and forensicanalysis.
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    Anisotropy of Young's modulus of human tibial cortical bone (2000)
    Springer
    Medical & biological engineering & computing 38 (2000), S. 333-338 
    Details
    ISSN: 1741-0444
    Keywords: Biomechanics ; Cortical bone ; Young's modulus ; Anisotropy ; Elasticity ; Ultrasonics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The anisotropy of Young's modulus in human cortical bone was determined for all spatial directions by performing coordinate rotations of a 6 by 6 elastic stiffness matrix. The elastic stiffness coefficients were determined experimentally from ultrasonic velocity measurements on 96 samples of normal cortical bone removed from the right tibia of eight human cadavers. The following measured values were used for our analysis: c 11 =19.5 GPa, c 22 =20.1 GPa, c 33 =30.9 GPa, c 44 =5.72 GPa, c 55 =5.17 GPa, c 66 =4.05 GPa, c 23 =12.5 GPa. The remaining coefficients were determined by assuming that the specimens possessed at least an orthorhombic elastic symmetry, and further assuming that c 13 =c 23 , c 12 =c 11 –2c 66 . Our analysis revealed a substantial anisotropy in Young's modulus in the plane containing the long axis of the tibia, with maxima of 20.9 GPa parallel to the long axis, and minima of 11.8 GPa perpendicular to this axis. A less pronounced anisotropy was observed in the plane perpendicular to the long axis of the tibia. To display our results for the full three-dimensional anisotropy of cortical bone, a closed surface was used to represent Young's modulus in all spatial directions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02347055
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  • 71
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    The Constructibility of Artificial Intelligence (as Defined by the Turing Test) (2000)
    Springer
    Journal of logic, language and information 9 (2000), S. 419-424 
    Details
    ISSN: 1572-9583
    Keywords: Artificial Intelligence ; computability ; constructibility ; culture ; evolution ; society ; symbol grounding ; Turing ; Turing Machine ; Turing Test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Linguistics and Literary Studies , Computer Science
    Notes: Abstract The Turing Test (TT), as originally specified, centres on theability to perform a social role. The TT can be seen as a test of anability to enter into normal human social dynamics. In this light itseems unlikely that such an entity can be wholly designed in an“off-line” mode; rather a considerable period of training insitu would be required. The argument that since we can pass the TT,and our cognitive processes might be implemented as a Turing Machine(TM), that consequently a TM that could pass the TT could be built, isattacked on the grounds that not all TMs are constructible in a plannedway. This observation points towards the importance of developmentalprocesses that use random elements (e.g., evolution), but in these casesit becomes problematic to call the result artificial. This hasimplications for the means by which intelligent agents could bedeveloped.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008363224791
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  • 72
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    Controllability of Second-Order Differential Inclusions in Banach Spaces with Nonlocal Conditions (2000)
    Springer
    Journal of optimization theory and applications 107 (2000), S. 559-571 
    Details
    ISSN: 1573-2878
    Keywords: nonlocal conditions ; mild solutions ; evolution ; controllability ; fixed points
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, we establish sufficient conditions for the controllability ofsecond-order differential inclusions in Banach spaces with nonlocalconditions. We rely on a fixed-point theorem for condensing maps due toMartelli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026447232030
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  • 73
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    Controllability and Stabilization in Elasticity, Heat Conduction and Thermoelasticity: Review of Recent Developments* (2000)
    Springer
    Journal of global optimization 17 (2000), S. 353-386 
    Details
    ISSN: 1573-2916
    Keywords: Approximation ; Elasticity ; Exact and approximate controllability ; Heat equations ; Stabilization ; Thermoelasticity ; Thermoviscoelasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The aim of this paper is to review developments in exact and approximate controllability as well as stabilization of elastic, thermoelastic, and thermo-viscoelastic bodies. Heat equations are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026596405554
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  • 74
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    Generalized stress intensity factors in the interaction between two fibers in matrix (2000)
    Springer
    International journal of fracture 103 (2000), S. 19-39 
    Details
    ISSN: 1573-2673
    Keywords: Elasticity ; composite material ; fracture mechanics ; fiber ; generalized stress intensity factor ; end effect ; interaction ; rectangular inclusions.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract To evaluate the mechanical strength of fiber reinforced composites it is necessary to consider singular stresses at the end of fibers because they cause crack initiation, propagation, and final failure. The singular stress is expressed by generalized stress intensity factors defined at the corner of fibers. As a 2D model an interaction between rectangular inclusions under longitudinal tension is treated in this paper. The body force method is used to formulate the problem as a system of singular integral equations with Cauchy-type or logarithmic-type singularities, where the unknown functions are the densities of body forces distributed in infinite plates having the same elastic constants as those of the matrix and inclusions. In order to analyze the problem accurately, the unknown functions are expressed as piecewize smooth functions using two types of fundamental densities and power series, where the fundamental densities are chosen to represent the symmetric stress singularity of 1/r 1−λ 1 and the skew-symmetric stress singularity of 1/r 1−λ 2. Then, generalized stress intensity factors at the end of inclusions are systematically calculated for various locations, spacings and elastic modulus of two rectangular inclusions in a plate subjected to longitudinal tension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007696723382
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  • 75
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    Breaking Through Artificial Selection Limits of an Adaptive Behavior in Mice and the Consequences for Correlated Responses (2000)
    Springer
    Behavior genetics 30 (2000), S. 193-206 
    Details
    ISSN: 1573-3297
    Keywords: Artificial selection ; correlated responses ; nest-building behavior ; Mus domesticus ; realized heritability ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Previous divergent selection for nest-building behavior at 22 ± 1°C resulted in a 40-fold difference between the high and the low lines in amount of cotton used to build a nest. Correlated responses to selection indicated positive genetic correlations with body weight, nest-building at 4 ± 1°C, and litter size and negative genetic correlations with food consumption. At generation 46, the replicate high-selected (High 1 × High 2), randomly bred control (Control 1 × Control 2), and low-selected (Low 1 × Low 2) lines were crossed and the F1 showed significant heterosis for nest-building behavior. Regression of the F3 on the F2 generation gave heritability estimates of 0.16 ± 0.10 for the high and 0.07 ± 0.10 for the low cross, revealing a potential to break the selection limit (at least in the high direction), which had been reached at about 20 generations of selection. Indeed, renewed selection resulted in responses in both the high and the low directions of nesting, yielding realized heritabilities of 0.29 ± 0.02 and 0.30 ± 0.004, respectively. Replicated renewed selection, using the F3 generation as the base population, in the high direction of nesting resulted in correlated increases in nest-building at 4 ± 1°C, litter size, and food consumption. Body weight did not change. The positive correlation with food consumption is opposite in sign compared to the original selection experiment. This indicates that the evolutionary potential of a population to adapt to a changing environment not only depends on its current genetic variability in one adaptive trait, but may be constrained by genetic correlations changing over the course of selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001962124005
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  • 76
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    Some like it hot: Intra-Population Variation in behavioral Thermoregulation in Color-Polymorphic pygmy Grasshoppers (2000)
    Springer
    Evolutionary ecology 14 (2000), S. 25-38 
    Details
    ISSN: 1573-8477
    Keywords: animal coloration ; body temperature ; ectotherm ; evolution ; Orthoptera ; poly-morphism ; Tetrix subulata ; thermoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ectothermic animals rely on external heat sources and behavioral thermoregulation to control body temperature, and are characterized by possessing physiological and behavioural traits which are temperature dependent. It has therefore been suggested that constraints on the range of body temperatures available to individuals imposed by phenotypic properties, such as coloration, may translate into differential fitness and selection against thermally inferior phenotypes. In this paper, I report an association between thermal preferences and thermal capacity (the ability to warm up when insolated) across different genetically coded color morphs of the pygmy grasshopper Tetrix subulata. Data on behavioral thermoregulation of individuals in a laboratory thermal gradient revealed a preference for higher body temperatures in females than in males, and significant variation among colour morphs in preferred body temperatures in females, but not in males. The variation in females was in perfect accordance with estimates of morph-specific differences in thermal capacity. Thus, dark morphs not only attain higher temperatures when exposed to augmented illumination, but also prefer higher body temperatures, compared to paler morphs. This intra-population divergence probably reflects an underlying variation among colour morphs in temperature optima, and is consistent with the notion that coloration, behaviour and physiology evolve in concert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011024320725
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    Electronic Resource
    The Bioeconomics of Cooperation (2000)
    Springer
    Journal of bioeconomics 2 (2000), S. 153-168 
    Details
    ISSN: 1573-6989
    Keywords: altruism ; culture ; evolution ; group selection ; natural selection ; new institutional economics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Economics
    Notes: Abstract When transactions and information are costly and exchange is non-simultaneous, ‘institutions matter’. They matter because exchange under these circumstances subjects the participants to potentially harmful behaviors by other participants, among which are: opportunistic behavior, agency, the free-rider problem, cheating, moral hazard, and adverse selection. Institutions constrain these behaviors, allowing the participants to take advantage of the gains from trade and specialization, and thereby facilitating cooperation. Individuals adhere to institutional rules because they gain by doing so. Because the individual gains are inseparable from the structure of the institutions, the institutions themselves necessarily become the focus of the analysis—as we see in the new institutional economics (NIE). The new group selection position in biology involves a similar shift in focus from the level of the individual to the group when studying the evolution of altruism. But some of the proponents of group selection go further, arguing that altruism in biology evolves because it is in the interest of the group, but not the individual. In fact, group level analysis is necessary in biology, as in the NIE, because it allows for the discovery of ‘institutions’ that constrain cheating, opportunistic behavior, etc., thereby making participation in the group in the long-run self-interest of the individual.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011466701827
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    Perspectives: neurobiology. The CRYs fo flies and mice (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-01-15
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hardin, P E -- Glossop, N R -- New York, N.Y. -- Science. 1999 Dec 24;286(5449):2460-1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, University of Houston, Houston, TX 77204, USA. phardin@uh.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10636810" target="_blank"〉PubMed〈/a〉
    Keywords: ARNTL Transcription Factors ; Animals ; Basic Helix-Loop-Helix Transcription Factors ; Biological Clocks/*physiology ; CLOCK Proteins ; Cell Cycle Proteins ; Circadian Rhythm/*physiology ; Cryptochromes ; Darkness ; Drosophila ; *Drosophila Proteins ; *Eye Proteins ; Feedback ; Flavoproteins/genetics/*physiology ; Gene Expression Regulation ; Light ; Mice ; Mice, Knockout ; Nuclear Proteins/*genetics/metabolism ; Period Circadian Proteins ; *Photoreceptor Cells, Invertebrate ; Promoter Regions, Genetic ; Receptors, G-Protein-Coupled ; Repressor Proteins/genetics/physiology ; Suprachiasmatic Nucleus/metabolism ; Trans-Activators/physiology ; Transcription Factors/physiology ; *Transcription, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    Photic induction of mPer1 and mPer2 in cry-deficient mice lacking a biological clock (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-01-05
    Description: Mice lacking mCry1 and mCry2 are behaviorally arrhythmic. As shown here, cyclic expression of the clock genes mPer1 and mPer2 (mammalian Period genes 1 and 2) in the suprachiasmatic nucleus and peripheral tissues is abolished and mPer1 and mPer2 mRNA levels are constitutively high. These findings indicate that the biological clock is eliminated in the absence of both mCRY1 and mCRY2 (mammalian cryptochromes 1 and 2) and support the idea that mammalian CRY proteins act in the negative limb of the circadian feedback loop. The mCry double-mutant mice retain the ability to have mPer1 and mPer2 expression induced by a brief light stimulus known to phase-shift the biological clock in wild-type animals. Thus, mCRY1 and mCRY2 are dispensable for light-induced phase shifting of the biological clock.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Okamura, H -- Miyake, S -- Sumi, Y -- Yamaguchi, S -- Yasui, A -- Muijtjens, M -- Hoeijmakers, J H -- van der Horst, G T -- New York, N.Y. -- Science. 1999 Dec 24;286(5449):2531-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Anatomy and Brain Science, Kobe University School of Medicine, Kobe 650-0017, Japan. okamurah@kobe-u.ac.jp〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10617474" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Clocks/*physiology ; Cell Cycle Proteins ; Circadian Rhythm/*physiology ; Cryptochromes ; *Drosophila Proteins ; *Eye Proteins ; Feedback ; Flavoproteins/genetics/*physiology ; Gene Expression Regulation ; In Situ Hybridization ; *Light ; Liver/metabolism ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mutation ; Nuclear Proteins/*genetics ; Period Circadian Proteins ; *Photoreceptor Cells, Invertebrate ; Polymerase Chain Reaction ; RNA, Messenger/genetics/metabolism ; Receptors, G-Protein-Coupled ; Retina/metabolism ; Suprachiasmatic Nucleus/metabolism ; Transcription Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    Leakage-resistant blood vessels in mice transgenically overexpressing angiopoietin-1 (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-01-05
    Description: Angiopoietin-1 (Ang1) and vascular endothelial growth factor (VEGF) are endothelial cell-specific growth factors. Direct comparison of transgenic mice overexpressing these factors in the skin revealed that the VEGF-induced blood vessels were leaky, whereas those induced by Ang1 were nonleaky. Moreover, vessels in Ang1-overexpressing mice were resistant to leaks caused by inflammatory agents. Coexpression of Ang1 and VEGF had an additive effect on angiogenesis but resulted in leakage-resistant vessels typical of Ang1. Ang1 therefore may be useful for reducing microvascular leakage in diseases in which the leakage results from chronic inflammation or elevated VEGF and, in combination with VEGF, for promoting growth of nonleaky vessels.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Thurston, G -- Suri, C -- Smith, K -- McClain, J -- Sato, T N -- Yancopoulos, G D -- McDonald, D M -- HL-24136/HL/NHLBI NIH HHS/ -- HL-59157/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1999 Dec 24;286(5449):2511-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Anatomy and Cardiovascular Research Institute, University of California, San Francisco, CA 94143-0452, USA. gavint@itsa.ucsf.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10617467" target="_blank"〉PubMed〈/a〉
    Keywords: Angiopoietin-1 ; Animals ; Arterioles/anatomy & histology/physiology ; Binding Sites ; Capillaries/anatomy & histology/physiology ; *Capillary Permeability ; Ear ; Endothelial Growth Factors/genetics/*physiology ; Endothelium, Vascular/metabolism ; Inflammation/chemically induced ; Inflammation Mediators/pharmacology ; Lymphokines/genetics/*physiology ; Membrane Glycoproteins/genetics/*physiology ; Mice ; Mice, Transgenic ; Microcirculation/anatomy & histology/*physiology ; Mustard Plant ; *Neovascularization, Physiologic ; Plant Extracts/pharmacology ; Plant Lectins ; Plant Oils ; Plants, Medicinal ; Platelet Activating Factor/pharmacology ; Ricin/metabolism ; Serotonin/pharmacology ; Skin/blood supply/metabolism ; Vascular Endothelial Growth Factor A ; Vascular Endothelial Growth Factors ; Venules/anatomy & histology/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    Role of the mouse ank gene in control of tissue calcification and arthritis (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-07-15
    Description: Mutation at the mouse progressive ankylosis (ank) locus causes a generalized, progressive form of arthritis accompanied by mineral deposition, formation of bony outgrowths, and joint destruction. Here, we show that the ank locus encodes a multipass transmembrane protein (ANK) that is expressed in joints and other tissues and controls pyrophosphate levels in cultured cells. A highly conserved gene is present in humans and other vertebrates. These results identify ANK-mediated control of pyrophosphate levels as a possible mechanism regulating tissue calcification and susceptibility to arthritis in higher animals.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ho, A M -- Johnson, M D -- Kingsley, D M -- 5T32GM07365/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2000 Jul 14;289(5477):265-70.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Developmental Biology and Howard Hughes Medical Institute, Beckman Center B300, Stanford University School of Medicine, Stanford, CA 94305-5327, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10894769" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arthritis/*genetics/metabolism/pathology ; Base Sequence ; Biological Transport ; COS Cells ; Calcinosis/*genetics ; Chromosome Mapping ; Cloning, Molecular ; Dna ; Diphosphates/*metabolism ; Durapatite/metabolism ; Gene Expression ; Genetic Complementation Test ; Humans ; Membrane Proteins/*genetics/metabolism/*physiology ; Mice ; Mice, Transgenic ; Molecular Sequence Data ; Mutation ; Phenotype ; Phosphate Transport Proteins ; Physical Chromosome Mapping ; Sequence Homology, Nucleic Acid ; Tissue Distribution
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    Regulation of area identity in the mammalian neocortex by Emx2 and Pax6 (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-04-15
    Description: The contribution of extrinsic and genetic mechanisms in determining areas of the mammalian neocortex has been a contested issue. This study analyzes the roles of the regulatory genes Emx2 and Pax6, which are expressed in opposing gradients in the neocortical ventricular zone, in specifying areas. Changes in the patterning of molecular markers and area-specific connections between the cortex and thalamus suggest that arealization of the neocortex is disproportionately altered in Emx2 and Pax6 mutant mice in opposing manners predicted from their countergradients of expression: rostral areas expand and caudal areas contract in Emx2 mutants, whereas the opposite effect is seen in Pax6 mutants. These findings suggest that Emx2 and Pax6 cooperate to regulate arealization of the neocortex and to confer area identity to cortical cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bishop, K M -- Goudreau, G -- O'Leary, D D -- NS31558/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 2000 Apr 14;288(5464):344-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10764649" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain Mapping ; Cadherins/biosynthesis/genetics ; DNA-Binding Proteins/*genetics/physiology ; Eye Proteins ; *Gene Expression ; Gene Expression Regulation, Developmental ; *Genes, Homeobox ; *Genes, Regulator ; Homeodomain Proteins/*genetics/physiology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred DBA ; Mice, Mutant Strains ; Morphogenesis ; Neocortex/*embryology/metabolism ; Neural Pathways ; Occipital Lobe/embryology/metabolism ; Paired Box Transcription Factors ; Repressor Proteins ; Somatosensory Cortex/embryology/metabolism ; Thalamus/embryology ; Transcription Factors ; Visual Cortex/embryology/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    Effects of environment on compensatory mutations to ameliorate costs of antibiotic resistance (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-02-26
    Description: Most types of antibiotic resistance impose a biological cost on bacterial fitness. These costs can be compensated, usually without loss of resistance, by second-site mutations during the evolution of the resistant bacteria in an experimental host or in a laboratory medium. Different fitness-compensating mutations were selected depending on whether the bacteria evolved through serial passage in mice or in a laboratory medium. This difference in mutation spectra was caused by either a growth condition-specific formation or selection of the compensated mutants. These results suggest that bacterial evolution to reduce the costs of antibiotic resistance can take different trajectories within and outside a host.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bjorkman, J -- Nagaev, I -- Berg, O G -- Hughes, D -- Andersson, D I -- New York, N.Y. -- Science. 2000 Feb 25;287(5457):1479-82.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Bacteriology, Swedish Institute for Infectious Disease Control, S-171 82 Solna, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10688795" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptation, Physiological ; Animals ; Anti-Bacterial Agents/*pharmacology ; *Antiporters ; Carrier Proteins/genetics ; Culture Media ; Drug Resistance, Microbial/*genetics ; Escherichia coli Proteins ; Evolution, Molecular ; Female ; Fusidic Acid/pharmacology ; Membrane Proteins/genetics ; Mice ; Mice, Inbred BALB C ; *Mutation ; Peptide Elongation Factor G/genetics ; Ribosomal Proteins/genetics ; Salmonella typhimurium/*drug effects/*genetics/growth & development/metabolism ; Selection, Genetic ; Serial Passage ; Streptomycin/pharmacology ; Suppression, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    Prostaglandin D2 as a mediator of allergic asthma (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-03-17
    Description: Allergic asthma is caused by the aberrant expansion in the lung of T helper cells that produce type 2 (TH2) cytokines and is characterized by infiltration of eosinophils and bronchial hyperreactivity. This disease is often triggered by mast cells activated by immunoglobulin E (IgE)-mediated allergic challenge. Activated mast cells release various chemical mediators, including prostaglandin D2 (PGD2), whose role in allergic asthma has now been investigated by the generation of mice deficient in the PGD receptor (DP). Sensitization and aerosol challenge of the homozygous mutant (DP-/-) mice with ovalbumin (OVA) induced increases in the serum concentration of IgE similar to those in wild-type mice subjected to this model of asthma. However, the concentrations of TH2 cytokines and the extent of lymphocyte accumulation in the lung of OVA-challenged DP-/- mice were greatly reduced compared with those in wild-type animals. Moreover, DP-/- mice showed only marginal infiltration of eosinophils and failed to develop airway hyperreactivity. Thus, PGD2 functions as a mast cell-derived mediator to trigger asthmatic responses.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Matsuoka, T -- Hirata, M -- Tanaka, H -- Takahashi, Y -- Murata, T -- Kabashima, K -- Sugimoto, Y -- Kobayashi, T -- Ushikubi, F -- Aze, Y -- Eguchi, N -- Urade, Y -- Yoshida, N -- Kimura, K -- Mizoguchi, A -- Honda, Y -- Nagai, H -- Narumiya, S -- New York, N.Y. -- Science. 2000 Mar 17;287(5460):2013-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, Kyoto University Faculty of Medicine, Kyoto 606-8501, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10720327" target="_blank"〉PubMed〈/a〉
    Keywords: Allergens/immunology ; Animals ; Asthma/immunology/metabolism/pathology/*physiopathology ; Bronchial Hyperreactivity ; Bronchoalveolar Lavage Fluid/cytology/immunology ; Crosses, Genetic ; Female ; Gene Targeting ; Humans ; Immunoglobulin E/blood ; Interferon-gamma/metabolism ; Interleukins/metabolism ; Lung/immunology/metabolism/pathology ; Lymphocytes/immunology ; Male ; Mast Cells/metabolism ; Mice ; Mice, Inbred C57BL ; Mucus/secretion ; Ovalbumin/immunology ; Prostaglandin D2/metabolism/*physiology ; *Receptors, Immunologic ; Receptors, Prostaglandin/genetics/metabolism/*physiology ; Respiratory Mucosa/secretion
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    Localized Rac activation dynamics visualized in living cells (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-10-13
    Description: Signaling proteins are thought to be tightly regulated spatially and temporally in order to generate specific and localized effects. For Rac and other small guanosine triphosphatases, binding to guanosine triphosphate leads to interaction with downstream targets and regulates subcellular localization. A method called FLAIR (fluorescence activation indicator for Rho proteins) was developed to quantify the spatio-temporal dynamics of the Rac1 nucleotide state in living cells. FLAIR revealed precise spatial control of growth factor-induced Rac activation, in membrane ruffles and in a gradient of activation at the leading edge of motile cells. FLAIR exemplifies a generally applicable approach for examining spatio-temporal control of protein activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kraynov, V S -- Chamberlain, C -- Bokoch, G M -- Schwartz, M A -- Slabaugh, S -- Hahn, K M -- AG15430/AG/NIA NIH HHS/ -- GM39434/GM/NIGMS NIH HHS/ -- R01 GM-57464/GM/NIGMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 2000 Oct 13;290(5490):333-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11030651" target="_blank"〉PubMed〈/a〉
    Keywords: 3T3 Cells ; Actins/metabolism ; Animals ; Biosensing Techniques ; Blood ; Cell Membrane/*enzymology/physiology/ultrastructure ; *Cell Movement ; Cell Nucleus/*enzymology ; Cell Polarity ; Enzyme Activation ; Fluorescence ; Guanosine Triphosphate/*metabolism ; Mice ; Nuclear Envelope/enzymology ; Platelet-Derived Growth Factor/pharmacology ; Recombinant Fusion Proteins/metabolism ; Spectrometry, Fluorescence ; rac1 GTP-Binding Protein/*metabolism
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  • 86
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    Selective inhibition of NF-kappaB activation by a peptide that blocks the interaction of NEMO with the IkappaB kinase complex (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-09-01
    Description: Activation of the transcription factor nuclear factor (NF)-kappaB by proinflammatory stimuli leads to increased expression of genes involved in inflammation. Activation of NF-kappaB requires the activity of an inhibitor of kappaB (IkappaB)-kinase (IKK) complex containing two kinases (IKKalpha and IKKbeta) and the regulatory protein NEMO (NF-kappaB essential modifier). An amino-terminal alpha-helical region of NEMO associated with a carboxyl-terminal segment of IKKalpha and IKKbeta that we term the NEMO-binding domain (NBD). A cell-permeable NBD peptide blocked association of NEMO with the IKK complex and inhibited cytokine-induced NF-kappaB activation and NF-kappaB-dependent gene expression. The peptide also ameliorated inflammatory responses in two experimental mouse models of acute inflammation. The NBD provides a target for the development of drugs that would block proinflammatory activation of the IKK complex without inhibiting basal NF-kappaB activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉May, M J -- D'Acquisto, F -- Madge, L A -- Glockner, J -- Pober, J S -- Ghosh, S -- AI 33443/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 2000 Sep 1;289(5484):1550-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Section of Immunobiology and Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10968790" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Anti-Inflammatory Agents, Non-Steroidal/chemistry/pharmacology ; COS Cells ; Cells, Cultured ; E-Selectin/biosynthesis/genetics ; Endothelium, Vascular/metabolism ; Gene Expression Regulation ; HeLa Cells ; Humans ; I-kappa B Kinase ; Inflammation/drug therapy ; Mice ; Mice, Inbred C57BL ; Molecular Sequence Data ; Mutation ; NF-kappa B/*metabolism ; Peptides/chemistry/*pharmacology ; Point Mutation ; Protein Structure, Tertiary ; Protein-Serine-Threonine Kinases/chemistry/genetics/*metabolism ; Recombinant Fusion Proteins/metabolism
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  • 87
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    A role for histone acetylation in the developmental regulation of VDJ recombination (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-01-22
    Description: VDJ recombination is developmentally regulated in vivo by enhancer-dependent changes in the accessibility of chromosomal recombination signal sequences to the recombinase, but the molecular nature of these changes is unknown. Here histone H3 acetylation was measured along versions of a transgenic VDJ recombination reporter and the endogenous T cell receptor alpha/delta locus. Enhancer activity was shown to impart long-range, developmentally regulated changes in H3 acetylation, and H3 acetylation status was tightly linked to VDJ recombination. H3 hyperacetylation is proposed as a molecular mechanism coupling enhancer activity to accessibility for VDJ recombination.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McMurry, M T -- Krangel, M S -- GM 41052/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2000 Jan 21;287(5452):495-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Immunology, Post Office Box 3010, Duke University Medical Center, Durham NC 27710, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10642553" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylation ; Animals ; Chromatin/metabolism ; DNA Nucleotidyltransferases/metabolism ; DNA-Binding Proteins/metabolism ; Enhancer Elements, Genetic ; *Gene Rearrangement, T-Lymphocyte ; *Genes, T-Cell Receptor alpha ; Genes, T-Cell Receptor beta ; *Genes, T-Cell Receptor delta ; Histones/*metabolism ; Homeodomain Proteins/metabolism ; Humans ; Mice ; Mice, Transgenic ; Nuclear Proteins ; Protein Sorting Signals ; *Recombination, Genetic ; T-Lymphocytes/*metabolism ; Transgenes ; VDJ Recombinases
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  • 88
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    Functional requirement for class I MHC in CNS development and plasticity (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-12-16
    Description: Class I major histocompatibility complex (class I MHC) molecules, known to be important for immune responses to antigen, are expressed also by neurons that undergo activity-dependent, long-term structural and synaptic modifications. Here, we show that in mice genetically deficient for cell surface class I MHC or for a class I MHC receptor component, CD3zeta, refinement of connections between retina and central targets during development is incomplete. In the hippocampus of adult mutants, N-methyl-D-aspartate receptor-dependent long-term potentiation (LTP) is enhanced, and long-term depression (LTD) is absent. Specific class I MHC messenger RNAs are expressed by distinct mosaics of neurons, reflecting a potential for diverse neuronal functions. These results demonstrate an important role for these molecules in the activity-dependent remodeling and plasticity of connections in the developing and mature mammalian central nervous system (CNS).〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2175035/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2175035/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huh, G S -- Boulanger, L M -- Du, H -- Riquelme, P A -- Brotz, T M -- Shatz, C J -- 1F32EY07016/EY/NEI NIH HHS/ -- EY06912/EY/NEI NIH HHS/ -- F32 EY007016/EY/NEI NIH HHS/ -- F32 EY007016-02/EY/NEI NIH HHS/ -- F32 EY007016-03/EY/NEI NIH HHS/ -- MH48108/MH/NIMH NIH HHS/ -- New York, N.Y. -- Science. 2000 Dec 15;290(5499):2155-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA. gshuh@alum.mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11118151" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD3/genetics/*physiology ; Brain/growth & development/*physiology ; Excitatory Postsynaptic Potentials ; Gene Expression Profiling ; Genes, MHC Class I ; Geniculate Bodies/physiology ; Hippocampus/growth & development/physiology ; Histocompatibility Antigens Class I/genetics/*physiology ; In Situ Hybridization ; Long-Term Potentiation ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Mice, Mutant Strains ; Neural Pathways ; *Neuronal Plasticity ; Neurons/*physiology ; Receptors, GABA-A/metabolism ; Receptors, N-Methyl-D-Aspartate/metabolism ; Retina/growth & development/physiology ; Retinal Ganglion Cells/physiology ; Signal Transduction ; Synapses/*physiology ; Synaptic Transmission ; Visual Pathways
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    Property claims. A deluge of patents creates legal hassles for research (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-04-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marshall, E -- New York, N.Y. -- Science. 2000 Apr 14;288(5464):255-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10777404" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biotechnology ; Drug Industry ; Europe ; Genome ; Mice ; *Mice, Knockout/genetics ; *Mice, Transgenic/genetics ; National Institutes of Health (U.S.) ; *Patents as Topic ; *Research/legislation & jurisprudence ; Sequence Analysis, DNA ; Technology Transfer ; United States ; Universities
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  • 90
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    Epitopes involved in antibody-mediated protection from Ebola virus (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-03-04
    Description: To determine the ability of antibodies to provide protection from Ebola viruses, monoclonal antibodies (mAbs) to the Ebola glycoprotein were generated and evaluated for efficacy. We identified several protective mAbs directed toward five unique epitopes on Ebola glycoprotein. One of the epitopes is conserved among all Ebola viruses that are known to be pathogenic for humans. Some protective mAbs were also effective therapeutically when administered to mice 2 days after exposure to lethal Ebola virus. The identification of protective mAbs has important implications for developing vaccines and therapies for Ebola virus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wilson, J A -- Hevey, M -- Bakken, R -- Guest, S -- Bray, M -- Schmaljohn, A L -- Hart, M K -- New York, N.Y. -- Science. 2000 Mar 3;287(5458):1664-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Virology Division, U.S. Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, Frederick, MD 21702-5011, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10698744" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Monoclonal/*immunology ; Antibodies, Viral/*immunology ; Antibody Affinity ; Antigens, Viral/immunology ; Binding, Competitive ; Complement System Proteins/immunology ; Ebolavirus/*immunology/physiology ; Epitopes/immunology ; Female ; Hemorrhagic Fever, Ebola/*prevention & control/therapy ; Humans ; Immunoglobulin G/immunology ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Neutralization Tests ; Specific Pathogen-Free Organisms ; Viral Envelope Proteins/*immunology ; Viral Plaque Assay
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  • 91
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    Crystal structure of a gammadelta T cell receptor ligand T22: a truncated MHC-like fold (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-01-15
    Description: Murine T10 and T22 are highly related nonclassical major histocompatibility complex (MHC) class Ib proteins that bind to certain gammadelta T cell receptors (TCRs) in the absence of other components. The crystal structure of T22b at 3.1 angstroms reveals similarities to MHC class I molecules, but one side of the normal peptide-binding groove is severely truncated, which allows direct access to the beta-sheet floor. Potential gammadelta TCR-binding sites can be inferred from functional mapping of T10 and T22 point mutants and allelic variants. Thus, T22 represents an unusual variant of the MHC-like fold and indicates that gammadelta and alphabeta TCRs interact differently with their respective MHC ligands.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wingren, C -- Crowley, M P -- Degano, M -- Chien, Y -- Wilson, I A -- AI33431/AI/NIAID NIH HHS/ -- CA58896/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 2000 Jan 14;287(5451):310-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10634787" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Amino Acid Substitution ; Animals ; Binding Sites ; Crystallography, X-Ray ; Glycosylation ; Histocompatibility Antigens Class I/*chemistry ; Hydrogen Bonding ; Ligands ; Mice ; Models, Molecular ; Point Mutation ; Protein Conformation ; Protein Folding ; Protein Structure, Quaternary ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Proteins/*chemistry/immunology/metabolism ; Receptors, Antigen, T-Cell, gamma-delta/immunology/*metabolism ; Surface Properties ; beta 2-Microglobulin/chemistry
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  • 92
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    Treatment of murine colitis by Lactococcus lactis secreting interleukin-10 (2000)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2000-08-26
    Description: The cytokine interleukin-10 (IL-10) has shown promise in clinical trials for treatment of inflammatory bowel disease (IBD). Using two mouse models, we show that the therapeutic dose of IL-10 can be reduced by localized delivery of a bacterium genetically engineered to secrete the cytokine. Intragastric administration of IL-10-secreting Lactococcus lactis caused a 50% reduction in colitis in mice treated with dextran sulfate sodium and prevented the onset of colitis in IL-10(-/-) mice. This approach may lead to better methods for cost-effective and long-term management of IBD in humans.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Steidler, L -- Hans, W -- Schotte, L -- Neirynck, S -- Obermeier, F -- Falk, W -- Fiers, W -- Remaut, E -- New York, N.Y. -- Science. 2000 Aug 25;289(5483):1352-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Ghent University and Flanders Interuniversity Institute for Biotechnology, K. L. Ledeganckstraat 35, 9000 Gent, Belgium. lothar.steidler@dmb.rug.ac.be〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10958782" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Transport ; Colitis/immunology/pathology/prevention & control/therapy ; Colon/immunology/metabolism/microbiology/pathology ; Dextran Sulfate ; Inflammatory Bowel Diseases/immunology/pathology/prevention & control/*therapy ; Interleukin-10/*administration & dosage/*biosynthesis/genetics/metabolism ; Intestinal Mucosa/metabolism/pathology ; Lactococcus lactis/*genetics/immunology/*metabolism ; Mice ; Probiotics/*therapeutic use ; Recombinant Proteins/administration & dosage/biosynthesis/metabolism
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  • 93
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    Involvement of cellular caveolae in bacterial entry into mast cells (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-08-05
    Description: Caveolae are subcellular structures implicated in the import and transcytosis of macromolecules and in transmembrane signaling. To date, evidence for the existence of caveolae in hematopoietic cells has been ambiguous. Caveolae were detected in the microvilli and intracellular vesicles of cultured mouse bone marrow-derived mast cells (BMMCs). CD48, a receptor for FimH-expressing (type 1 fimbriated) Escherichia coli, was specifically localized to plasmalemmal caveolae in BMMCs. The involvement of caveolae in bacterial entry into BMMCs was indicated because caveolae-disrupting and -usurping agents specifically blocked E. coli entry, and markers of caveolae were actively recruited to sites of bacterial entry. The formation of bacteria-encapsulating caveolar chambers in BMMCs represents a distinct mechanism of microbial entry into phagocytes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shin, J S -- Gao, Z -- Abraham, S N -- AI 35678/AI/NIAID NIH HHS/ -- CA 14236/CA/NCI NIH HHS/ -- DK 50814/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 2000 Aug 4;289(5480):785-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Departments of Pathology and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10926542" target="_blank"〉PubMed〈/a〉
    Keywords: Adhesins, Bacterial/*metabolism ; *Adhesins, Escherichia coli ; Animals ; Antigens, CD/analysis/*metabolism ; Bacterial Adhesion ; Caveolin 1 ; *Caveolins ; Cell Fractionation ; Cell Membrane/chemistry/*metabolism/microbiology/ultrastructure ; Cholera Toxin/pharmacology ; Cyclodextrins/pharmacology ; *Endocytosis ; Escherichia coli/*metabolism/pathogenicity ; *Fimbriae Proteins ; Glycosylphosphatidylinositols/analysis ; Mast Cells/*metabolism/*microbiology/ultrastructure ; Membrane Proteins/analysis ; Mice ; Microscopy, Confocal ; Microscopy, Fluorescence ; Microscopy, Immunoelectron
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    Intellectual property. NIH cuts deal on use of OncoMouse (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-02-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marshall, E -- New York, N.Y. -- Science. 2000 Jan 28;287(5453):567.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10691532" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Mice ; *Mice, Transgenic ; *National Institutes of Health (U.S.) ; *Neoplasms, Experimental ; *Patents as Topic ; Research Support as Topic ; United States
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    Lipid research. Possible new way to lower cholesterol (2000)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2000-09-19
    Description: Clinicians may soon be able to mount a multipronged attack against cholesterol, the artery-clogging lipid whose buildup in the body is a major contributor to heart attacks and other cardiovascular diseases. In work reported on page 1524, a team has pinpointed a biological master switch in mice that controls three pathways that work together to both rid the body of excess cholesterol and prevent its absorption from the intestine. The work suggests a new mechanism for reducing cholesterol, for example, with drugs that turn up the activity of the master switch, a protein known as the retinoid X receptor.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ferber, D -- New York, N.Y. -- Science. 2000 Sep 1;289(5484):1446-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10991725" target="_blank"〉PubMed〈/a〉
    Keywords: ATP Binding Cassette Transporter 1 ; ATP-Binding Cassette Transporters/*metabolism ; Animals ; Bile Acids and Salts ; Biological Transport/drug effects ; Cholesterol/*metabolism ; Cholesterol, Dietary/administration & dosage ; DNA-Binding Proteins/metabolism ; Glycoproteins/*metabolism ; Humans ; Intestinal Absorption/drug effects ; Intestines/drug effects/*metabolism ; Liver/metabolism ; Macrophages/metabolism ; Mice ; Orphan Nuclear Receptors ; *Receptors, Cytoplasmic and Nuclear ; Receptors, Retinoic Acid/*metabolism ; Receptors, Thyroid Hormone/metabolism ; Retinoid X Receptors ; Transcription Factors/*metabolism
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    Immunology. A touch of antibody class (2000)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2000-06-08
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stavnezer, J -- New York, N.Y. -- Science. 2000 May 12;288(5468):984-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, 55 Lake Avenue N., Worcester, MA 01655, USA. Janet.Stavnezer@umassmed.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10841719" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; B-Lymphocytes/*immunology ; Cytokines/immunology ; DNA/genetics/*metabolism ; Genes, Immunoglobulin ; *Immunoglobulin Class Switching ; Immunoglobulin Heavy Chains/genetics ; *Immunoglobulin Switch Region ; Mice ; Mice, Transgenic ; Models, Genetic ; *Nucleic Acid Hybridization ; RNA/genetics/*metabolism ; RNA Splicing ; Recombination, Genetic ; Ribonuclease H/genetics/metabolism ; Templates, Genetic ; Transcription, Genetic
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  • 97
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    Regulation of cell fate decision of undifferentiated spermatogonia by GDNF (2000)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2000-02-26
    Description: The molecular control of self-renewal and differentiation of stem cells has remained enigmatic. Transgenic loss-of-function and overexpression models now show that the dosage of glial cell line-derived neurotrophic factor (GDNF), produced by Sertoli cells, regulates cell fate decisions of undifferentiated spermatogonial cells that include the stem cells for spermatogenesis. Gene-targeted mice with one GDNF-null allele show depletion of stem cell reserves, whereas mice overexpressing GDNF show accumulation of undifferentiated spermatogonia. They are unable to respond properly to differentiation signals and undergo apoptosis upon retinoic acid treatment. Nonmetastatic testicular tumors are regularly formed in older GDNF-overexpressing mice. Thus, GDNF contributes to paracrine regulation of spermatogonial self-renewal and differentiation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Meng, X -- Lindahl, M -- Hyvonen, M E -- Parvinen, M -- de Rooij, D G -- Hess, M W -- Raatikainen-Ahokas, A -- Sainio, K -- Rauvala, H -- Lakso, M -- Pichel, J G -- Westphal, H -- Saarma, M -- Sariola, H -- New York, N.Y. -- Science. 2000 Feb 25;287(5457):1489-93.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Research Programs of Developmental Biology, Molecular Neurobiology, Electron Microscopy Unit, Institute of Biotechnology, Viikki Biocenter, Finland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10688798" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Apoptosis/drug effects ; Cell Cycle ; Cell Differentiation/drug effects ; Cobalt/metabolism ; *Drosophila Proteins ; Female ; Gene Expression ; Gene Targeting ; Glial Cell Line-Derived Neurotrophic Factor ; Glial Cell Line-Derived Neurotrophic Factor Receptors ; Male ; Mice ; Mice, Transgenic ; Mitosis ; *Nerve Growth Factors ; Nerve Tissue Proteins/genetics/*physiology ; Proto-Oncogene Proteins/genetics/metabolism ; Proto-Oncogene Proteins c-ret ; Receptor Protein-Tyrosine Kinases/genetics/metabolism ; Sertoli Cells/cytology/physiology ; *Spermatogenesis ; Spermatogonia/*cytology/drug effects ; Stem Cells/*cytology ; Testicular Neoplasms/pathology ; Testis/anatomy & histology ; Vitamin A/pharmacology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 98
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    Two-amino acid molecular switch in an epithelial morphogen that regulates binding to two distinct receptors (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-10-20
    Description: Ectodysplasin, a member of the tumor necrosis factor family, is encoded by the anhidrotic ectodermal dysplasia (EDA) gene. Mutations in EDA give rise to a clinical syndrome characterized by loss of hair, sweat glands, and teeth. EDA-A1 and EDA-A2 are two isoforms of ectodysplasin that differ only by an insertion of two amino acids. This insertion functions to determine receptor binding specificity, such that EDA-A1 binds only the receptor EDAR, whereas EDA-A2 binds only the related, but distinct, X-linked ectodysplasin-A2 receptor (XEDAR). In situ binding and organ culture studies indicate that EDA-A1 and EDA-A2 are differentially expressed and play a role in epidermal morphogenesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yan, M -- Wang, L C -- Hymowitz, S G -- Schilbach, S -- Lee, J -- Goddard, A -- de Vos, A M -- Gao, W Q -- Dixit, V M -- New York, N.Y. -- Science. 2000 Oct 20;290(5491):523-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Oncology, Genentech, 1 DNA Way, South San Francisco, CA 94080, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11039935" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Amino Acid Substitution ; Animals ; Binding Sites ; Cell Line ; DNA-Binding Proteins/metabolism ; Ectodermal Dysplasia/genetics ; Ectodysplasins ; Epidermis/embryology/*metabolism ; Humans ; *I-kappa B Proteins ; In Situ Hybridization ; Ligands ; Membrane Proteins/*chemistry/*metabolism ; Mice ; Models, Molecular ; Molecular Sequence Data ; Morphogenesis ; NF-kappa B/metabolism ; Phosphorylation ; Point Mutation ; Protein Conformation ; Proteins/metabolism ; Receptors, Cell Surface/chemistry/genetics/*metabolism ; Recombinant Fusion Proteins/metabolism ; Signal Transduction ; TNF Receptor-Associated Factor 6 ; Transfection
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 99
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    Induction and maintenance of the neuronal cholinergic phenotype in the central nervous system by BMP-9 (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-07-15
    Description: Bone morphogenetic proteins (BMPs) have multiple functions in the developing nervous system. A member of this family, BMP-9, was found to be highly expressed in the embryonic mouse septum and spinal cord, indicating a possible role in regulating the cholinergic phenotype. In cultured neurons, BMP-9 directly induced the expression of the cholinergic gene locus encoding choline acetyltransferase and the vesicular acetylcholine transporter and up-regulated acetylcholine synthesis. The effect was reversed upon withdrawal of BMP-9. Intracerebroventricular injection of BMP-9 increased acetylcholine levels in vivo. Although certain other BMPs also up-regulated the cholinergic phenotype in vitro, they were less effective than BMP-9. These data indicate that BMP-9 is a differentiating factor for cholinergic central nervous system neurons.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lopez-Coviella, I -- Berse, B -- Krauss, R -- Thies, R S -- Blusztajn, J K -- P01 AG09525/AG/NIA NIH HHS/ -- New York, N.Y. -- Science. 2000 Jul 14;289(5477):313-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Psychiatry and Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA 02118, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10894782" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylcholine/biosynthesis ; Animals ; Bone Morphogenetic Proteins/*physiology ; Carrier Proteins/genetics ; Cells, Cultured ; Central Nervous System ; Choline O-Acetyltransferase/genetics ; Embryo, Mammalian/metabolism ; Fibroblast Growth Factor 2/physiology ; Gene Expression Regulation, Developmental ; Gene Expression Regulation, Enzymologic ; Growth Differentiation Factor 2 ; *Membrane Transport Proteins ; Mice ; Neurons/metabolism ; Phenotype ; RNA, Messenger/metabolism ; Septum of Brain/embryology/metabolism ; Spinal Cord/embryology/metabolism ; Up-Regulation ; Vesicular Acetylcholine Transport Proteins ; *Vesicular Transport Proteins
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 100
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    Transgenic mouse model of stunned myocardium (2000)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2000-01-22
    Description: Stunned myocardium is a syndrome of reversible contractile failure that frequently complicates coronary artery disease. Cardiac excitation is uncoupled from contraction at the level of the myofilaments. Selective proteolysis of the thin filament protein troponin I has been correlated with stunned myocardium. Here, transgenic mice expressing the major degradation product of troponin I (TnI1-193) in the heart were found to develop ventricular dilatation, diminished contractility, and reduced myofilament calcium responsiveness, recapitulating the phenotype of stunned myocardium. Proteolysis of troponin I also occurs in ischemic human cardiac muscle. Thus, troponin I proteolysis underlies the pathogenesis of a common acquired form of heart failure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murphy, A M -- Kogler, H -- Georgakopoulos, D -- McDonough, J L -- Kass, D A -- Van Eyk, J E -- Marban, E -- HL 44065/HL/NHLBI NIH HHS/ -- HL 63038/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 2000 Jan 21;287(5452):488-91.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pediatrics, Johns Hopkins University School of Medicine, Ross Building 1144, 720 Rutland Avenue, Baltimore, MD 21205, USA. murphy@jhmi.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10642551" target="_blank"〉PubMed〈/a〉
    Keywords: Actin Cytoskeleton/metabolism ; Adrenergic beta-Agonists/pharmacology ; Animals ; Calcium/metabolism ; Cardiomegaly/pathology ; Dilatation, Pathologic ; *Disease Models, Animal ; Heart Rate ; Heart Ventricles/pathology ; Humans ; Isoproterenol/pharmacology ; Mice ; Mice, Inbred C57BL ; *Mice, Transgenic ; Myocardial Contraction ; Myocardial Stunning/*metabolism/pathology/physiopathology ; Myocardium/*metabolism/pathology ; Myofibrils/metabolism ; Troponin I/genetics/*metabolism ; Ventricular Function, Left
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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