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  • phosphorus  (208)
  • Drosophila  (203)
  • evolution  (202)
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  • 2020-2024
  • 1990-1994  (596)
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  • 1
    Digitale Medien
    Digitale Medien
    Are the oviposition traits of the South India strain of Callosobruchus maculatus maintained by natural selection? (1990)
    Springer
    Entomologia experimentalis et applicata 57 (1990), S. 143-150 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Bruchidae ; Callosobruchus maculatus ; competition ; development ; evolution ; fecundity ; growth rates ; host preferences ; life tables ; mortality ; natural selection ; net reproductive rate ; oviposition traits
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé Le taux partiel de reproduction nette (R inf0 sup* ) dépend de l'espèce de la plante sur laquelle les œufs sont pondus et du nombre de larves entrant dans la graine. La survie larvaire est réduite par 1/(le nombre de larves par graine) parce qu'une seule larve se développe dans une graine. La fécondité n'est pas modifiée par la compétition subie par les larves, la mortalité larvaire a l'effet le plus important sur R inf0 sup* . Les femelles éliminent ou réduisent la compétition larvaire en dispersant leurs œufs uniformément et font si peu d'erreurs avec une hyperdispersion que l'évolution d'un comportement plus précis n'accroîtrait R inf0 sup* que de 4% au maximum. Des femelles retournant à une distribution des œufs au hasard provoqueraient une réduction de R inf0 sup* de 25% au moins. Les légumineuses généralement cultivées dans l'Inde du Sud sont des hôtes acceptables quand elles sont présentées seules. Le choix des femelles entre 2 hôtes élève R inf0 sup* de 30% ou plus par rapport à une distribution au hasard. Les préférences les plus nettes concernent des combinaisons présentant la plus grande différence de R inf0 sup* . Les femelles qui hyperdispersent leurs œufs, choisissent leurs hôtes et évitent les pertes par compétition en empêchant que les œufs ne donnent plus de descendants que ne le ferait une ponte au hasard. Les particularités de la ponte sont variables et héritables. Les lignées se sélectionnent bien, en fonction de la dispersion de leurs œufs sur les graines, de la discrimination des plantes hôtes, et de la modulation de leur taux de ponte. La sélection naturelle maintient ces particularités du comportement d'une façon sédentaire.
    Notizen: Abstract The deposition of eggs by this strain of Callosobruchus maculatus (Fab.) (Bruchidae: Coleoptera) departs from randomness in three ways; eggs are uniformly dispersed, oviposition rates drop when beans begin to carry 2 or more eggs, and there are sharp host preferences. Using random egg placement for the unspecialized condition, these traits are evaluated for their effect on a female's contributions of offspring to the next generation (R0, the net reproductive rate). The major increases in R0 result from females dispersing eggs so uniformly that larval competition is either reduced or eliminated. Females reduce their oviposition rate when the larva from an egg added to a bean is almost certain to die in competitive encounters. Host preferences and larval survival in a host are positively associated with the abundance of the host in South India. The three oviposition traits act together to give and R0 that is 25–50% than that of eggs placed at random. These traits are known to be variable and heritable, hence, the conditions necessary for natural selection are statisfied.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00343502
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  • 2
    Digitale Medien
    Digitale Medien
    Conserving genetic variability of a wild insect population under laboratory conditions (1993)
    Springer
    Entomologia experimentalis et applicata 67 (1993), S. 233-239 
    Details
    ISSN: 1570-7458
    Schlagwort(e): inbreeding ; colonization ; isofemale line ; Drosophila ; Diptera ; Leptopilina boulardi ; Cynipidae ; Hymenoptera
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé D. melanogaster (Meigen) a été utilisé pour tester la capacité des lignées isofemelles à conserver la variabilité génétique d'une population naturelle. Deux types d'expériences ont été réalisées. L'une a consisté à déterminer la variabilité génétique de 3 locus enzymatiques pour 32 lignées isofemelles à la première et à la 23ème génération d'élevage au laboratoire. L'autre a consisté à tester la capacité des larves à éliminer un parasitoïde par le processus d'encapsulation après 8 années d'élevage au laboratoire. D'une façon générale, certaines lignées isofemelles perdent de la variabilité durant les 23 générations de l'étude. Mais la fréquence globale des allèles reste inchangée si l'on considère l'ensemble des 32 lignées. Le seul allèle rare observé a également été conservé. Les modifications des fréquences allèliques à chacun des locus ont lieu de façon indépendante les unes des autres. La variabilité génétique d'un caractère biologique, la capacité des larves à encapsuler le parasitoïde, a également varié, mais elle a pu être restaurée à un niveau proche de la population initiale en rassemblant plusieurs individus de chacune des lignées.
    Notizen: Abstract Drosophila melanogaster (Meigen) was used to test the power of isofemale lines in preserving genetic variability. We performed experiments in two ways. One series consisted of measuring the genetic variability for three enzymatic loci in 32 isofemale lines, in the first and 23rd generations of culture. In the second series, we tested the capacity of the larvae to eliminate a parasitoid by encapsulation after eight years of laboratory breeding. In general, individual isofemale lines appeared to change during the 23 generations of the study, but the global frequency of these alleles among the 32 isofemale lines stayed relatively unchanged. The only rare allele observed was also conserved. Changes in allozyme frequencies at any one locus were independent of those at other loci. Genetic variation of a biological trait, the capacity of the larvae to encapsulate a parasitoid, also changed, but it could be restored to a level close to that of the starting population by mass hybridizing together individuals of each line.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02383432
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  • 3
    Digitale Medien
    Digitale Medien
    Variation between strains of the flour beetle Tribolium castaneum in relative performance on five flours (1991)
    Springer
    Entomologia experimentalis et applicata 60 (1991), S. 173-182 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Genetics ; evolution ; host adaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract When populations are exposed to different environments, evolutionary processes can lead either to genetically differentiated strains or to the appearance of increased generalism at the individual level. For evolution to occur, genetic variability in performance in different environments is required. Here, intraspecific genetic variation across environments was estimated in the flour beetle Tribolium castaneum (Herbst) by comparing the responses of two strains of T. castaneum to different flour types. Replicated groups from each strain were allowed to develop on either the standard whole wheat medium or on one of four novel flours (wheat, rice, corn and oat). In several of the novel flours, clear differences in mean development time or population size of one or both strains were seen relative to performance in the standard medium. Moreover, the strains differed significantly in their phenotypic responses to the flours. One strain did particularly poorly on oat flour. Reduced oviposition, reduced larval survivorship and increased larval cannibalism were examined as possible causes of the low productivity on oat flour. These three factors accounted for about 70% of the reduction in population size when this strain oviposited and developed in oat flour. The difference between these two outbred strains in response to these five flours suggests that genetic variation in resource use is present within T. castaneum and may also be present within strains and natural populations in grain storage facilities. Such variation would permit an evolutionary response to selection in multiple environments (flours). This process has agricultural implications when several types of grain are stored in a single location because it could eventually lead to the evolution of highly generalized populations of T. castaneum, an important pest of stored products.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00177038
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  • 4
    Digitale Medien
    Digitale Medien
    Responses of a generalist and a specialist parasitoid (Hymenoptera: Eucoilidae) to Drosophilid larval kairomones (1993)
    Springer
    Journal of insect behavior 6 (1993), S. 615-624 
    Details
    ISSN: 1572-8889
    Schlagwort(e): Hymenoptera ; Leptopilina ; Drosophila ; semiochemicals ; kairomones ; parasitoid ; generalist ; specialist ; foraging behavior
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Foraging parasitoids are thought to need more specific information than generalists on the presence, identity, availability, and suitability of their insect host species. In the present paper, we compare responses to host kairomones by two phylogenetically related parasitoid species that attack Drosophilidae and that differ in the width of their host range. As predicted, the behavioral response of the parasitoids to host kairomones reflected their difference in host range. The response of the specialist parasitoid Leptopilina boulardiwas restricted to contact kairomones from its natural hosts and one closely related species. In contrast, the generalist parasitoid Leptopilina heterotomaresponded to contact kairomones of a variety of Drosophilidae species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01048127
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  • 5
    Digitale Medien
    Digitale Medien
    Cockroach mating behaviors, sex pheromones, and abdominal glands (Dictyoptera: Blaberidae) (1993)
    Springer
    Journal of insect behavior 6 (1993), S. 715-735 
    Details
    ISSN: 1572-8889
    Schlagwort(e): Aphrodisiac ; cockroach ; evolution ; mating behavior ; sex pheromone ; sternal glands ; tergal glands
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two chemical signals are essential in all cockroach sexual behavioral sequences: the sex pheromone released by one partner, generally the female (for long distance attraction), and an aphrodisiac sex pheromone produced exclusively by male tergal glands (for female mounting and tergal contact or “feeding” behavior). Unlike the other cockroach groups, the males of the Oxyhaloinae species produce both chemical signals: the pheromone and the aphrodisiac. The occurrence of three patterns of mating behavior (A, B, and C), the production of male sex pheromones, and the existence in the male of developed sternal and tergal glands in seven related Oxyhaloinae species, make these cockroaches a useful model for studying the evolution of mating behavior patterns. The various types of mating behavior were not classified in the previous studies by Roth and Barth. In this report, they have been named type A (female in upper position), B (male in upper position), and C (male and female end to end). In type A mating, the male tergal glands, which are licked by the females, are well developed, whereas in types B and C, there is no licking of the male's tergal secretion by the females and the tergal glands are much less developed; the aphrodisiacs secreted by the tergal glands may no longer act in this case through contact chemoreception, but through an olfactory process involving volatile components. One common sex pheromone component seems to be acetoin. I suggest that the mating behavior tends from A toward B and C during the evolutionary process with a concomitant regression of the tergal glands and changes in the aphrodisiac emission levels. The mating behavioral sequences of cockroaches (Dictyoptera) and crickets (Orthoptera) show a striking degree of similarity and are probably examples of convergent evolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01201672
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  • 6
    Digitale Medien
    Digitale Medien
    Egg attendance and brooding by males of the giant water bugLethocerus medius (Guerin) in the field (Heteroptera: Belostomatidae) (1993)
    Springer
    Journal of insect behavior 6 (1993), S. 93-106 
    Details
    ISSN: 1572-8889
    Schlagwort(e): Belostomatidae ; giant water bugs ; paternal care ; eggs ; reproduction ; behavior ; brooding ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Males of the giant water bug Lethocerus medius(Guerin) typify their monobasic subfamily, the Lethocerinae, in that they do not brood eggs attached to their backs as do males of all members of the subfamily Belostomatinae. Exclusive male parental investment as expressed in the Belostomatinae is extremely rare behavior among animals, and evolution of the trait is obscure. Lethocerus mediusmales apparently remain with their mates through oviposition and are consistently found in attendance of eggs after the female has departed. This behavior may enhance paternity assurance at no cost in opportunity for polygyny. Two double clutches of eggs were found, from which we infer the potential for polygynous matings and shared parental investment. Male L. mediusbrood attended egg clutches above the surface of the water, where they may moisten them, shade them, and defend them against predation. Egg attendance/brooding by L. mediusand other Lethocerusspecies may represent a plesiomorphic state from which paternal back- brooding evolved in the Belostomatinae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01049150
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  • 7
    Digitale Medien
    Digitale Medien
    Unrewarding experiences and their effect on foraging in the parasitic waspLeptopilina heterotoma (Hymenoptera: Eucoilidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 465-481 
    Details
    ISSN: 1572-8889
    Schlagwort(e): host selection ; experience ; learning ; extinction ; reinforcement ; parasitoids ; Drosophila ; Leptopilina heterotoma ; Hymenoptera ; Eucoilidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The host-foraging behavior of female entomophagous parasitoids is commonly modified by positive associative learning. Typically, a rewarding experience (e.g., successful oviposition in a host) increases a female's foraging effort in a host microhabitat of the type associated with that experience. Less well understood are the effects of unrewarding experiences (i.e., unsuccessful foraging). The influence of unrewarding experience on microhabitat choice and residence time within a microhabitat was examined for the eucoilid parasitoid,Leptopilina heterotoma, in laboratory and greenhouse assays. As determined previously, females which oviposited successfully in either of two microhabitat types (fermenting apple or decaying mushroom) strongly preferred to forage subsequently on that microhabitat type. However, failure to find hosts in the formerly rewarding microhabitat caused females to reverse their preference in favor of a novel microhabitat type. The effect, though striking, was transient: within 1–2 h, the original learned preference was nearly fully restored. Similar effects of unrewarding experiences were observed with respect to the length of time spent foraging in a microhabitat. As determined previously, oviposition experience in a particular microhabitat type increased the time spent foraging in a patch of that microhabitat type. However, failure to find hosts in the patch caused the time a wasp spent in the next unoccupied patch of that type to decrease to almost nothing. In addition, there was a tendency for an unrewarding experience on a formerly rewarding microhabitat type to extend the time spent in a patch of a novel type. The function of the observed effects of unrewarding experiences is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02025444
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  • 8
    Digitale Medien
    Digitale Medien
    Drosophila do not skew offspring sex ratio as predicted by trivers and willard (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 8 (1994), S. 231-239 
    Details
    ISSN: 1572-8889
    Schlagwort(e): Drosophila ; sex ratio ; life history ; optimality model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Based on both previously published literature and results reported here, it appears thatDrosophila melanogaster meet the explicit assumptions of the Trivers and Willard offspring sex allocation model. However, contrary to the model's predictions, offspring sex ratio was not significantly affected when we manipulated factors that influence offspring quality. We suggest that contrary to implicit predictions of offspring sex ratio models,Drosophila may lack the genetic plasticity to readily alter sex ratio.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01988907
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  • 9
    Digitale Medien
    Digitale Medien
    Egg-laying experience and acceptance of parasitized hosts by the parasitoid,Leptopilina heterotoma (Hymenoptera: Eucoilidae) (1994)
    Springer
    Journal of insect behavior 8 (1994), S. 331-342 
    Details
    ISSN: 1572-8889
    Schlagwort(e): parasitoid ; superparasitism ; learning ; motivation ; egg load ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The influence of egg-laying experience on the response of females of the eucoilid parasitoid,Leptopilina heterotoma, to parasitized and unparasitizedDrosophila melanogaster host larvae was examined under more controlled conditions than those used in past studies. In laboratory assays, we precisely manipulated both the number of eggs laid by females and the kind of larvae (parasitized versus unparasitized) in which the eggs were laid. We found that the tendency to avoid laying eggs in parasitized hosts depended markedly on whether or not eggs had been laid previously, but depended little on whether those eggs had been laid in parasitized or unparasitized hosts. The observed effect of general egg-laying experience on avoidance of parasitized hosts may reflect responses to either changes in the wasp's internal state (perhaps, changes in egg load) or changes in the wasp's neural representation of the external environment (such as those presumed to occur during learning). In light of these results, we offer a tentative reinterpretation of several earlier studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01989362
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  • 10
    Digitale Medien
    Digitale Medien
    Courtship success and multivariate analysis of sexual selection on morphometric traits inDrosophila buzzatii (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 8 (1994), S. 219-229 
    Details
    ISSN: 1572-8889
    Schlagwort(e): Drosophila ; sexual selection gradients ; courtship success
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Using wild-reared flies, we examined sexual selection on five phenotypic traits (thorax length, wing length, wing width, head width, and face width) inDrosophila buzzatii, by scoring copulatory status in nine mass mating cages. Only male face width was identified as a direct target of sexual selection in an analysis of selection gradient, while indirect selection was present on all other studied traits, as expected from their correlations with face width. In contrast to males, there was no indication of selection in females. Nor was there evidence of assortative mating. The suggested direct selection on face width seems to take place during licking behavior of the courtship and might be related to courtship feeding. This study suggests that courtship success gives rise to indirect selection on body size.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01988906
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  • 11
    Digitale Medien
    Digitale Medien
    Parasitization of embedded and nonembeddedDrosophila melanogaster (Diptera: Drosophilidae) pupae by the parasitoidPachycrepoideus vindemniae (Hymenoptera: Pteromalidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 129-131 
    Details
    ISSN: 1572-8889
    Schlagwort(e): Drosophila ; parasitoid wasp ; behavior ; genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01989833
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  • 12
    Digitale Medien
    Digitale Medien
    The effects of acclimation and rearing conditions on the response of tropical and temperate populations ofDrosophila melanogaster andD. simulans to a temperature gradient (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 279-288 
    Details
    ISSN: 1572-8889
    Schlagwort(e): temperature preference ; Drosophila ; acclimation ; compensation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effects of rearing and acclimation on the response of adultDrosophila to temperature were investigated in a gradient.D. melanogaster flies preferred a higher mean temperature and were distributed over a wider range of temperatures thanD. simulans flies. Acclimating adults at different temperatures for a week did not influence the response of either species. Adults reared at 28°C as immatures had a lower mean preference than those reared at cooler temperatures, suggesting that flies compensated for the effects of rearing conditions. Adults from tropical and temperate populations ofD. melanogaster andD. simulans did not differ in the mean temperature they preferred in a gradient, suggesting little genetic divergence for this trait within species. The species differences and environmental responses may be related to changes in optimal physiological conditions for the flies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01989735
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  • 13
    Digitale Medien
    Digitale Medien
    Sensorimotor transformation from light reception to phototactic behavior inDrosophila larvae (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 553-567 
    Details
    ISSN: 1572-8889
    Schlagwort(e): review ; Drosophila ; larva ; phototaxis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In this paper we examine theDrosophila melanogaster larval response to light. We survey the morphology of the larval visual and motor systems in relation to larval locomotory behavior and phototaxis. In addition, this paper proposes a model of sensorimotor transformation and examines the reversal in taxis occurring at theD. melanogaster larval wnadering stage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02025449
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  • 14
    Digitale Medien
    Digitale Medien
    The ecosystem of a mesotrophic lake-II. Interactions among nutrient load, river flow, and epilimnion depth (1991)
    Springer
    Aquatic sciences 53 (1991), S. 263-272 
    Details
    ISSN: 1420-9055
    Schlagwort(e): Lake ecosystem ; chl-a ; phosphorus ; nitrogen ; river flow ; thermocline ; simulation model ; multiple regression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The management variables which primarily affect phytoplankton biomass (as chl-a) in Lake Mjøsa, Norway, are total phosphorus loading (TP) and the timing and volume of water through flow (by active storage reservoirs). The response of the lake to changes in these factors is studied using a simulation model of the lake ecosystem. Chl-a responses from both observed data and the simulated results are extracted by multiple regression. Results show that decreasing TP load decreases chl-a, but less at low TP levels (〈 10 mg TP · m−3). There is also a certain time period for peak river flow which gives the least yield of chl-a per unit TP. This time period occurs in early summer (i.e., around June 10) if the total phosphorus load is low, and later if the load is high. Both observations and simulation results show that a high water flow increases chl-a at low epilimnion depths (〈 15 m), but that the same high water flow decreases chl-a when epilmnion is deep.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00877062
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  • 15
    Digitale Medien
    Digitale Medien
    Ancient DNA: An introduction (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 521-523 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Ancient DNA ; evolution ; conservation ; biology ; anthropology ; plant biology ; PCR (polymerase chain reaction)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01921719
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  • 16
    Digitale Medien
    Digitale Medien
    A novel mechanism for jumping in the indian antHarpegnathos saltator (Jerdon) (Formicidae, Ponerinae) (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 63-71 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Insect ; behaviour ; high-speed cinematography ; jumping ; electrophysiology ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The Indian antHarpegnathos saltator may be unique among insects in using its jumping capacity not only as an escape mechanism but also as a normal means of locomotion, and for catching its prey in flight. High-speed cinematography used to analyse the various phases of the jump suggests thatHarpegnathos employs a novel jumping mechanism to mediate these behaviours: namely the synchronous activation of its middle and hindlegs. Electrophysiological recordings from muscles or nerves in pairs of middle and hindlegs show remarkably synchronous activity during fictive jumping, supporting the synchronous activation hypothesis.Harpegnathos is not the only ant to jump, and a cladistic analysis suggests that jumping behaviour evolved independently three times during ant evolutionary history.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01992052
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  • 17
    Digitale Medien
    Digitale Medien
    The short term response to eutrophication abatement (1990)
    Springer
    Aquatic sciences 52 (1990), S. 199-220 
    Details
    ISSN: 1420-9055
    Schlagwort(e): Eutrophication ; lake management ; phosphorus ; ecosystem ; chlorophyll-a ; mathematical modelling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We compare results of a new model for predicting the short term inter annual changes in chlorophyll-a (chl-a) in lakes after reductions in total phosphorus (TP) to predictions made by least squares regression models. In the new method, slopes of chl-a/TP graphs (both axes in mg · m−3) are depicted in frequency diagrams and used to extract information on the expected, short term chl-a/TP response. The short term response for nine shallow (〈 10 m deep) and nutrient rich lakes to changes in TP was found to be: Chl-a = 0.49 · TP + 17.3, and for nine deep, P-limited lakes: Chl-a = 0.08 · TP + 3.5. If the TP-reduction is known to be greater than 10 mg · m−3, the expected slope increases to 0.58 for shallow lakes and to 0.26 for deep lakes. The slope, 0.58, is 8% lower than the slope for the long term response calculated by regression for the shallow lakes. For deep lakes the slope, 0.26, is 2 to 3 times higher than that calculated by regression, indicating that reductions in TP for deep lakes give greater effects than least squares regression equations suggest. We have also calculated the reduction in TP which will give about 80% probability that a reduction in chl-a will be observed next year. For shallow, P-limited lakes this reduction is about 30 mg · m−3 (5% of average initial in-lake TP concentration), and for deep lakes about 14 mg · m−3 (35% of average initial in-lake TP concentration).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00877280
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  • 18
    Digitale Medien
    Digitale Medien
    Vertical mixing in Überlinger See, western part of Lake Constance (1990)
    Springer
    Aquatic sciences 52 (1990), S. 256-268 
    Details
    ISSN: 1420-9055
    Schlagwort(e): Vertical mixing ; stratification ; phosphorus ; Lake Constance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Depth variable vertical eddy diffusion coefficients for heat (K z) were calculated from continuously measured temperature profiles in Überlinger See (western part of Lake Constance). The temperatures were averaged over vertical intervals of 10 m yielding 14 discrete values (maximum depth of Überlinger See: 147 m). A linear fit from 10 June to 29 September 1987 was used to smooth the significant temperature fluctuations caused by internal seiches of Lake Constance. Assuming horizontal homogeneity for the smoothed data the Gradient-Flux-Method was applied to compute vertical diffusion coefficientsK z at different depths using the depth variable volumes and surfaces of the 14 layers. The resulting mean diffusion coefficients for the period from June to September are 0.04 cm2/s near the thermocline and up to 0.8 cm2/s in deeper strata (accuracy: ± 50%). It is shown that horizontal mixing between Überlinger See and Obersee (main lake) alters the computation ofK z by less than 50%. A relationship betweenK z and stability (Brunt-Väisälä) frequencyN is found which corresponds well to the theory of internal wave induced turbulence. Combining the diffusion coefficients with measured phosphorus profiles, a phosphorus flux from the hypolimnion to the epilimnion of (0.7 ± 0.4) mg P m−2 d−1 was calculated, corresponding to about 20% of the average external loading per area of Lake Constance in 1986.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00877283
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  • 19
    Digitale Medien
    Digitale Medien
    Measurement of total dissolved phosphorus in small volumes of iron rich interstitial water (1992)
    Springer
    Aquatic sciences 54 (1992), S. 1-9 
    Details
    ISSN: 1420-9055
    Schlagwort(e): Sediment ; interstitial water ; phosphorus ; iron ; persulfate digestion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract It is shown that sorption of orthophosphate to iron compounds, formed during persulfate digestion, can cause a significant underestimation of total dissolved phosphorus in interstitial waters rich in iron and poor in phosphorus. Labelling the samples with carrier free32PO4 before digestion allows to correct for these losses.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00877261
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  • 20
    Digitale Medien
    Digitale Medien
    Eucaryotic codes (1990)
    Springer
    Cellular and molecular life sciences 46 (1990), S. 1106-1117 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Genetic code ; eucaryotic cell ; evolution ; code ambiguity ; code universality ; convergence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary This article is a review of the rules used by eucaryotic cells to translate a nuclear messenger RNA into a polypeptide chain. The recent observation that these rules are not identical in two species of a same phylum indicates that they have changed during the course of evolution. Possible scenarios for such changes are presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01936920
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  • 21
    Digitale Medien
    Digitale Medien
    Can we predict the mating pattern ofDrosophila females from the sperm length distribution in males? (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 111-114 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Drosophila ; repeat matings ; polyandrous pattern diversity ; sperm length
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In order to test the validity of the prediction of the mating pattern of females from the sperm length distribution in males, three species ofDrosophila were analysed. Males in the three species are equally polygynous but females differ in the level of polyandry. A ‘low recurrence polyandry’ is observed in the sperm dimorphic speciesD. affinis while a ‘high recurrence polyandry’ is observed in the sperm monomorphic speciesD. latifasciaeformis andD. littoralis. These results are consistent with the hypothesis proposed previously that sperm dimorphism in males can only be maintained by a selective alternative in females (i.e. facultative female polygamy), whereas a stricter mating system (e.g., ‘obligatory’ polyandry) should only result in sperm monomorphism irrespective of the absolute value of sperm length.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02041270
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  • 22
    Digitale Medien
    Digitale Medien
    Biology of halophilic bacteria, Part II (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 1027-1036 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Archaea (archaebacteria) ; extreme halophiles ; archaeol phospholipids ; archaeol glycolipids ; membrane function ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Archaebacteria (archaea) are comprised of three groups of prokaryotes: extreme halophiles, methanogens and thermoacidophiles (extreme thermophiles). Their membrane phospholipids and glycolipids are derived entirely from a saturated, isopranoid glycerol diether,sn-2,3-diphytanylglycerol (‘archaeol’) and/or its dimer, dibiphytanyldiglyceroltetraether (‘caldarchaeol’). In extreme halophiles, the major phospholipid is the archaeol analogue of phosphatidylglycerolmethylphosphate (PGP-Me); the glycolipids are sulfated and/or unsulfated glycosyl archaeols with diverse carbohydrate structure characteristic of taxons on the generic level. Biosynthesis of these archaeol-derived polar lipids occurs in a multienzyme, membrane-bound system that is absolutely dependent on high salt concentration (4 M). The highly complex biosynthetic pathways involve intermediates containing glycerol ether-linked C20-isoprenyl groups which are reduced to phytanyl groups to give the final saturated polar lipids. In methanogens, polar lipids are derived both from archaeol and caldarchaeol, and thermoacidophiles contain essentially only caldarchaeol-derived polar lipids. The function of these membrane polar lipids in maintaining the stability, fluidity and ionic properties of the cell membrane of extreme halophiles, as well as the evolutionary implications of the archaeol and caldarchaeol-derived structures will be discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01929909
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  • 23
    Digitale Medien
    Digitale Medien
    Presence of a partial urea cycle in the leech,Poecilobdella granulosa (1992)
    Springer
    Cellular and molecular life sciences 48 (1992), S. 729-731 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Urea cycle ; leech ; botryoidal tissue ; hirudineans ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Ornithine carbamoyltransferase (OCT) and arginase, but not arginine synthetase (AS), were detected in the body wall and gut tissues of the leech. The activities of these enzymes were not altered by starvation. The high activity of arginase in body wall is probably due to the association of the latter with botryoidal tissue. Hirudineans, which evolved from oligochaete ancestors, appear to have lost the citrulline-arginine segment of the urea cycle due to their ammonotelic mode of nitrogen excretion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02124288
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  • 24
    Digitale Medien
    Digitale Medien
    Genetic aspects of the hsp70 multigene family in vertebrates (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 987-1001 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Hsp70 ; evolution ; gene duplication ; gene homology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The family of genes encoding heat shock proteins of about 70 kDa (hsp70) in vertebrates is reviewed under genetic aspects. After a detailed description of the various hsp70 genes more general characteristics of the organization and evolution of the multigene family are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01923453
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  • 25
    Digitale Medien
    Digitale Medien
    Chitin in the epidermal cuticle of a vertebrate (Paralipophrys trigloides, Blenniidae, Teleostei) (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 317-319 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Chitin ; cuticle ; evolution ; vertebrates ; bony fish ; Blenniidae ; Paralipophrys trigoides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Lectin binding, endo-chitinase binding and enzymatic degradation studies show that the epidermal cuticle of the bony fishParalipophrys trigloides (Blenniidae) is chitinous. This is the first evidence that a vertebrate species possesses a chitinous tissue. Recently aXenopus gene has been identified which has significant sequence similarity to the catalytic domain of yeast chitin synthase III, a chitin producing enzyme1,2. Taken together these two findings imply that chitin synthesis capability may be a basic vertebrate feature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01923410
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  • 26
    Digitale Medien
    Digitale Medien
    Sexual isolation betweenDrosophila melanogaster females andD. simulans males. Male mating propensities versus success in hybridization (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 596-598 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Drosophila ; hybridization ; male vigour ; male mating speed
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Genetic variation has been found in males of aD. simulans population for their eagerness to hybridize withD. melanogaster females. In a search for traits involved in this hybridization, males ofD. simulans were tested for mating speed and sexual vigour. Between-male differences were detected in both sexual traits, but no relationship was noticed between them, nor with the frequency of hybridization. Thus male mating propensities appear to be unrelated to the breakdown of sexual isolation between these sibling species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01955171
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  • 27
    Digitale Medien
    Digitale Medien
    Genetic ecology: A new interdisciplinary science, fundamental for evolution, biodiversity and biosafety evaluations (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 429-437 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Genetics ; ecology ; DNA-transfer ; conjugation ; transformation ; transduction ; transposons ; dormant cells ; epilithon ; microbial colonisation ; symbiosis ; virus resistance ; biosafety ; release of genes ; insults to humanity ; evolution ; biodiversity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Genetic ecology is the extension of our modern knowledge in molecular genetics to studies of viability, gene expression and gene movements in natural environments like soils, aquifers and digestive tracts. In such milieux, the horizontal transfer of plasmid-borne genes between phylogenetically distant species has already been found to be much more frequent than had been expected from laboratory experience. For the study of exchanges involving chromosomally-located genes, more has to be learned about the behaviour of transposons in such environments. The results expected from studies in genetic ecology are relevant for considerations of evolution, biodiversity and biosafety. The role of this new field of research in restoring popular confidence in science and in its biotechnological applications is stressed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01920741
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  • 28
    Digitale Medien
    Digitale Medien
    Basic rules of change (1990)
    Springer
    Journal for general philosophy of science 21 (1990), S. 231-257 
    Details
    ISSN: 1572-8587
    Schlagwort(e): basic rules ; change ; discipline-neutral ; evolution ; analogy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Philosophie , Wissenschaftskunde und Wissenschaftsorganisation, Hochschul- und Universitätswesen, Museumswissenschaft
    Notizen: Summary A small step is made in the direction of defining some general basic rules which can serve as a framework for research in several fields of the social sciences. The method of working with analogies asks for a more accurate approach. Starting from the concept of evolution in the form of a basic rule another basic rule is formulated. This rule shows what are the most important factors in long term developments and what types of development one can expect.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01801037
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  • 29
    Digitale Medien
    Digitale Medien
    Evolution: Teleology or chance? (1991)
    Springer
    Journal for general philosophy of science 22 (1991), S. 133-141 
    Details
    ISSN: 1572-8587
    Schlagwort(e): evolution ; teleology ; chance ; purpose ; anthropomorphism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Philosophie , Wissenschaftskunde und Wissenschaftsorganisation, Hochschul- und Universitätswesen, Museumswissenschaft
    Notizen: Summary Revaluation of the problem of natural teleology seems an important precondition for elucidating our environmental crisis and for formulating an ‘ecological ethics’, because it calls for a recognition of an intrinsic value in nature and organisms. Therefore, it is necessary to show that the concept of natural teleology is not in contradiction with scientific theories, in particular not with the theory of evolution. In this paper I shall argue that there is a fundamental misunderstanding about the concepts of teleology and chance in modern thinking. This as a result of a radical transformation of the Aristotelian concept of teleology by Christian theologians during the Middle Ages. This confusion resulted in the rejection of teleology from evolution and in an exaggeration of the role of chance. However, not a solution for the problem of teleology is given here, but only an attempt to prove that neither the fossil-record, nor the role of chance in evolution can give adequate arguments for the negation of teleology in evolution. That is not to say that, therefore there exists teleology in evolution, but the problem of teleology in nature cannot, be solved by the scientific theory of evolution, but only be elucidated by philosophical analysis. At the end of the paper it is argued that teleology must be rather presupposed in evolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01801253
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  • 30
    Digitale Medien
    Digitale Medien
    Life and teleology (1992)
    Springer
    Journal for general philosophy of science 23 (1992), S. 85-103 
    Details
    ISSN: 1572-8587
    Schlagwort(e): life ; teleology ; evolution ; reality ; representation ; experience
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Philosophie , Wissenschaftskunde und Wissenschaftsorganisation, Hochschul- und Universitätswesen, Museumswissenschaft
    Notizen: Summary A comprehensive definition of the phenomenon called “life” led to the addition of many dimensions to the natural sciences, and especially the conscious mental dimension. Historical attention is paid not only to those employing the natural philosophical paradigms, but also to evolutionary theories and to the Kantian teleological philosophy. The belief that science can solve the riddle of life is a category of purposal thinking. A revised version of critical teleology is essential for comprehension of life.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01801797
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  • 31
    Digitale Medien
    Digitale Medien
    Evolution of insect-plant relationships — a devil's advocate approach (1993)
    Springer
    Entomologia experimentalis et applicata 66 (1993), S. 3-12 
    Details
    ISSN: 1570-7458
    Schlagwort(e): evolution ; coevolution ; selection ; insect attack ; plant defense ; competition ; enemy free space ; chemoreception ; specialization ; plant recognition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Most hypotheses concerning the evolution of insect-plant relationships are based on the assumptions that, (1) phytophagous insects reduce plant fitness, and that (2) insect-plant relationships are the result of unconstrained selection. It can be shown, however, that there is little evidence to support these assumptions. As an alternative, it is proposed that the evolution of insect-plant relationships results primarily from autonomous evolutionary events; namely from heritable functional changes within the insects' nervous system that determine plant recognition and ultimately host plant specificity. These changes cannot be evoked by selective ecological agents. They originate from intrinsic changes (mutationssensu lato) within the insect genome. Ecological factors play a secondary role: by either supporting or preventing the establishment of the new genotype with the novel food preference.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02381541
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  • 32
    Digitale Medien
    Digitale Medien
    Evolutionary genetics of the aphid Cryptomyzus, with a preliminary analysis of the inheritance of host plant preference, reproductive performance and host-alteration (1990)
    Springer
    Entomologia experimentalis et applicata 57 (1990), S. 65-76 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Cryptomyzus ; aphid ; hybridization ; host plant preference ; reproductive performance ; host-alternation ; speciation ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé C. galeopsidis Kaltenbach contient plusieurs formes qui ont différentes relations avec des plantes hôtes et des cycles distincts. Des croisements ont permis d'élucider la taxonomie de ces formes et d'étudier l'hérédité de préférences d'hôtes, des performances reproductives et de l'alternance d'hôtes. Une des formes apparaît comme une espèce distincte par suite de la valeur adaptative réduite des hybrides. Les autres formes avec alternance ou non des hôtes sont considérées comme conspécifiques et représentant deux stratégies vitales différentes. Les performances reproductives sont probablement polygéniques puisque les hybrides ont des performances intermédiaires. Les préférences d'hôtes des hybrides montrent certains degrés de dominance et semblent déterminées par quelques gènes seulement. L'alternance des hôtes est envisagée comme ayant une hérédité monofactorielle. Les conséquences sur la spéciation sont discutées.
    Notizen: Abstract The aphid species Cryptomyzus galeopsidis (Kaltenbach) includes several distinct forms which have different host plant relationships and life cycles. Cross breeding was used to elucidate the taxonomic status of these forms and to investigate the inheritance of host preference, reproductive performance and host-alternation. One of the forms appeared to be a distinct species because of the reduced fitness of the hybrids. Other host-alternating and non host-alternating forms are considered conspecific and represent two life cycle strategies. Reproductive performance is probably controlled polygenically, since hybrids show an intermediate performance. Host preference in hybrids showed some degree of dominance and seemed to be determined by only a few genes. Host-alternation is presumed to be inherited monofactorially. The implications for speciation are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00349596
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  • 33
    Digitale Medien
    Digitale Medien
    Mitochondrial DNA sequence divergence in theMelanogaster and oriental species subgroups ofDrosophila (1991)
    Springer
    Journal of molecular evolution 33 (1991), S. 156-162 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Mitochondrial DNA ; Nucleotide sequence ; Nonsynonymous substitutions ; Phylogeny ; A+T content
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The nucleotide sequence of a segment of the mitochondrial DNA from threeDrosophila species (D. erecta, D. eugracilis, andD. takahashii), belonging to different subgroups of themelanogaster group has been determined. The segment encompasses three complete tRNA genes (tRNAtrp, tRNAcys, and tRNAtyr) and portions of two protein-coding genes: the subunit 2 of the NADH dehydrogenase (ND2) and the subunit 1 of the cytochrome oxidase (COI). Comparisons also involve homologous sequences already known for four otherDrosophila species of themelanogaster group. Length differences were confined in the intergenic region where a long stretch of AT repeats was observed in one of the species analyzed. The three tRNA genes exhibit very different evolutionary rates, the most slowly evolving one, tRNAtyr, is adjacent to the 5′ end of COI; tRNAs in similar positions have been previously shown to evolve slowly because they are probably involved in transcript processing. Although the rate of synonymous substitutions was very similar between ND2 and COI genes there were strong discrepancies between them in terms of the number of nonsynonymous substitutions. Differences have also been found in G+C content of the genes, which are likely to be linked to different selective pressures. There is a reduction in G+C content in the region where selective constraints are reduced. This suggests the existence of different levels of constraints along the sequenced segment. An overall analysis of the types of substitutions showed a decrease in A+T content during the course of evolution of the species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02193630
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  • 34
    Digitale Medien
    Digitale Medien
    Unusual organizational features of the Drosophila Gart locus are not conserved within diptera (1992)
    Springer
    Journal of molecular evolution 35 (1992), S. 51-59 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Gart locus ; Chironomus tentans ; Purine nucleotide biosynthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The Drosophila Gart locus consists of two genes. One gene encodes three enzymes in the de novo purine nucleotide biosynthesis pathway [glycinamide ribonucleotide synthetase (GARS), aminoimidazole ribonucleotide synthetase (AIRS), and glycinamide ribonucleotide transformylase (GART)]. The second gene lies within an intron of the purine gene and encodes a cuticle protein. To investigate the evolution of the Gart locus, the Chironomus tentans homolog was cloned by screening a genomic DNA library with a polymerase chain reaction product. This study shows that the interesting structural features of this locus conserved in two distant Drosophila species are not found in the Chironomus homolog. These features include the cuticle protein gene nested within an intron and the existence of an alternative transcript to yield a monofunctional enzyme. In addition, the extremely rapid divergence of coding sequence seen for members of the tandemly duplicated AIRS domain in Drosophila is found to be much less rapid in Chironomus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160260
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  • 35
    Digitale Medien
    Digitale Medien
    Homopolymer length variation in the Drosophila gene mastermind (1993)
    Springer
    Journal of molecular evolution 37 (1993), S. 483-495 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; mastermind ; Gene comparison ; Triplet repeat ; Homopolymer ; Protein evolution ; Repeat length variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Runs of identical amino acids encoded by triplet repeats (homopolymers) are components of numerous proteins, yet their role is poorly understood. Large numbers of homopolymers are present in the Drosophila melanogaster mastermind (mam) protein surrounding several unique charged amino acid clusters. Comparison of mam sequences from D. virilis and D. melanogaster reveals a high level of amino acid conservation in the charged clusters. In contrast, significant divergence is found in repetitive regions resulting from numerous amino acid replacements and large insertions and deletions. It appears that repetitive regions are under less selective pressure than unique regions, consistent with the idea that homopolymers act as flexible spacers separating functional domains in proteins. Notwithstanding extensive length variation in intervening homopolymers, there is extreme conservation of the amino acid spacing of specific charge clusters. The results support a model where homopolymer length variability is constrained by natural selection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160429
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  • 36
    Digitale Medien
    Digitale Medien
    Evolution of the threonine-glycine repeat region of the period gene in the melanogaster species subgroup of drosophila (1992)
    Springer
    Journal of molecular evolution 35 (1992), S. 411-419 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; per gene ; Threonine-Glycine ; repeat sequence ; melanogaster subgroup phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The Threonine-Glycine (Thr-Gly) region of the period gene (per) in Drosophila was compared in the eight species of the D. melanogaster subgroup. This region can be divided into a diverged variable-length segment which is flanked by more conserved sequences. The number of amino acids encoded in the variable-length region ranges from 40 in D. teissieri to 69 in D. mauritiana. This is similar to the range found within natural populations of D. melanogaster. It was possible to derive a Thr-Gly “allele” of one species from that of another by invoking hypothetical Thr-Gly intermediates. A phylogeny based on the more conserved flanking sequences was produced. The results highlighted some of the problems which are encountered when highly polymorphic genes are used to infer phylogenies of closely related species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00171819
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  • 37
    Digitale Medien
    Digitale Medien
    ADH and phylogenetic relationships ofDrosophila lebanonensis (Scaptodrosophila) (1991)
    Springer
    Journal of molecular evolution 32 (1991), S. 421-428 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Alcohol dehydrogenase ; Amino acid sequence ; Phylogenetic relationships ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Increasing data onDrosophila alcohol dehydrogenase (ADH) sequences have made it possible to calculate the rate of amino acid replacement per year, which is 1.7×10−9. This value makes this protein suitable for reconstructing phylogenetic relationships within the genus for those species for which no molecular data are available such asScaptodrosophila. The amino acid sequence ofDrosophila lebanonensis is compared to all of the already knownDrosophila ADHs, stressing the unique characteristic features of this protein such as the conservation of an initiating methionine at the N-terminus, the unique replacement of a glycine by an alanine at a very conserved position in the NAD domain of all dehydrogenases, the lack of a slowmigrating peptide, and the total conservation of the maximally hydrophilic peptide. The functional significance of these features is discussed. Although the percent amino acid identity of the ADH molecule inDrosophila decreases as the number of sequences compared increases, the conservation of residue type in terms of size and hydrophobocity for the ADH molecule is shown to be very high throughout the genusDrosophila. The distance matrix and parsimony methods used to establish the phylogenetic relationships ofD. lebanonensis show that the three subgenera,Scaptodrosophila, Drosophila, andSophophora separated at approximately the same time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02101282
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  • 38
    Digitale Medien
    Digitale Medien
    Evolution of thedec-1 eggshell locus inDrosophila. I. Restriction site mapping and limited sequence comparison in themelanogaster species subgroup (1991)
    Springer
    Journal of molecular evolution 33 (1991), S. 321-331 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; dec-1 locus ; Restriction map conservation ; Sequence comparison ; Melanogaster species subgroup ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have analyzed ∼18 kb of DNA in and upstream of thedefective chorion-1 (dec-1) locus of the eight known species of themelanogaster species subgroup ofDrosophila. The restriction maps ofD. simulans, D. mauritiana, D. sechellia, D. erecta, andD. orena are shown to have basically the restriction map ofD. melanogaster, whereas the maps ofD. teissieri andD. yakuba were more difficult to align. However, the basic amount of DNA and sequence arrangement appear to have been conserved in these species. A small deletion of varying length (65–200 bp) is found in a repeated sequence of the central transcribed region ofD. melanogaster, D. simulans, andD. erecta. Restriction site mapping indicated that thedec-1 gene is highly conserved in themelanogaster species subgroup. However, sequence comparison revealed that the amount of nucleotide and amino acid substitution in the repeated region is much larger than in the 5′ translated region. The 5′ flanking region showed noticeable restriction site polymorphisms between species. Based on calculations from the restriction maps a dendrogram was derived that supports earlier published phylogenetic relationships within themelanogaster species subgroup except that theerecta-orena pair is placed closer to themelanogaster complex than toD. teissieri andD. yakuba.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02102863
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  • 39
    Digitale Medien
    Digitale Medien
    Insertion sites of the transposable elementmariner are fixed in the genome ofDrosophila sechellia (1991)
    Springer
    Journal of molecular evolution 33 (1991), S. 450-456 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Mariner ; Transposable elements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The abundance of the transposable elementmariner differs dramatically in the genomes of the closely related speciesDrosophila simulans, D. mauritiana, D. sechellia, andD. melanogaster. Natural populations ofD. simulans andD. mauritiana have 1–10 and 20–30 copies per diploid genome, respectively, and the insertion sites are polymorphic. The element has not been found inD. melanogaster. In this paper we show thatD. sechellia, a species endemic to the Seychelles Islands, contains only twomariner elements that are at fixed sites in the genome. One element, inserted in chromosome 2R at 51A1–2, contains three deletions and is missing much of the 3′ end. The other element, inserted in chromosome 3L at 64A10–11, is the full length of 1286 bp. Although the sequence of the full-length element is polymorphic in populations ofD. sechellia, at least some of the sequences are closely related to elements fromD. simulans andD. mauritiana that are known to be active. However, judging from the progeny of crosses betweenD. sechellia andD. simulans, the biological activity of the full-lengthD. sechellia element appears to be low, either because of the nucleotide sequence of the element or because of its position in the genome, or both.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02103137
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  • 40
    Digitale Medien
    Digitale Medien
    Molecular phylogeny of Drosophila based on ribosomal RNA sequences (1993)
    Springer
    Journal of molecular evolution 37 (1993), S. 525-543 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Zaprionus ; Phylogeny ; Ribosomal RNA sequences
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nucleotide sequences of 72 species of Drosophilidae were determined for divergent D1 and D2 domains (representing 200 and 341 nucleotides respectively in D. melanogaster) of large ribosomal RNA, using the rRNA direct sequencing method. Molecular phylogenetic trees were reconstructed using both distance and parsimony methods and the robustness of the nodes was evaluated by the bootstrap procedure. The trees obtained by these methods revealed four main lineages or clades which do not correspond to the taxonomical hierarchy. In our results, the genus Chymomyza is associated with the subgenus Scaptodrosophila of the genus Drosophila and their cluster constitutes the most ancient clade. The two other clades are constituted of groups belonging to the subgenus Sophophora of the genus Drosophila: the so-called Neotropical clade including the willistoni and saltans groups and the obscura-melanogaster clade itself split into three lineages: (1) obscura group + ananassae subgroup, (2) montium subgroup, and (3) melanogaster + Oriental subgroups. The fourth clade, the Drosophila one, contains three lineages. D. polychaeta, D. iri, and D. fraburu are branched together and constitute the most ancient lineage; the second lineage includes the annulimana, bromeliae, dreyfusi, melanica, mesophragmatica, repleta, robusta, and virilis groups. The third lineage is composed of the immigrans and the cardini, funebris, guaramunu, guarani, histrio, pallidipennis, quinaria, and tripunctata groups. The genera Samoaia, Scaptomyza, and Zaprionus are branched within the Drosophila clade. Although these four clades appear regularly in almost all tree calculations, additional sequencing will be necessary to determine their precise relationships.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160433
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  • 41
    Digitale Medien
    Digitale Medien
    Complementary DNA-DNA hybridization in Drosophila (1992)
    Springer
    Journal of molecular evolution 34 (1992), S. 130-140 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Sophophora ; cDNA-DNA hybridization ; Phylogenetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have performed DNA-DNA hybridization experiments among several species of Drosophila using the evolutionarily conserved portion of the genome representing sequences coding for amino acids of proteins. This was done by using as tracer, radioactively labeled complementary DNA that was reverse transcribed from adult mRNA. We show that this procedure extends phylogenetically the distance over which the technique can be applied to fast-evolving groups such as Drosophila. The major phylogenetic conclusions are (1) the subgenus Sophophora is a monophyletic lineage; (2) within Sophophora the melanogaster subgroup is closer to the obscura group than either group is to the willistoni group; (3) the subgenus Drosophila is complex with most major lineages originating deep in the phylogeny; the subgenus may not be monophyletic; (4) as with most groups classically placed in Drosophila, the Hawaiian Drosophila originate early, supporting the notion that this lineage is older than the extant islands; and (5) the virilis/repleta lineage is monophyletic within Drosophila.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00182390
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  • 42
    Digitale Medien
    Digitale Medien
    Evolution of thedec-1 eggshell locus inDrosophila. II. Intraspecific DNA sequence analysis reveals length mutations in a repetitive region inD. melanogaster (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 536-544 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; dec-1 eggshell gene ; Wild-type variants ; Repeated region ; DNA sequencing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Thedec-1 eggshell gene inDrosophila melanogaster encodes follicle cell proteins required for proper eggshell assembly. As shown by Southern and Northern analyses thedec-1 gene occurs in four alleles (Fcl-4) among wild-type strains. Its second exon has a distinct feature in the form of 12 repeats with 78–91 nucleotides; the first five show nearly 100% homology. DNA sequence comparison of the repeated region of the alleles revealed that the length polymorphisms are caused by changes in the numbers of the first five repeats. The results suggest that the alleles have been generated by unequal intragenic crossing-over and/or slippage during DNA replication and that the allelic length variants have arisen independently. The possiblilty that the most common allele,FC1, has a selective advantage over the other alleles is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00556358
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  • 43
    Digitale Medien
    Digitale Medien
    Phylogeny of the Drosophila obscura species group deduced from mitochondrial DNA sequences (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 478-488 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Mitochondrial DNA ; Nucleotide sequences ; Drosophila ; Rapid phyletic radiation ; Molecular phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Approximately 2 kb corresponding to different regions of the mtDNA of 14 different species of the obscura group of Drosophila have been sequenced. In spite of the uncertainties arising in the phylogenetic reconstruction due to a restrictive selection toward a high mtDNA A+T content, all the phylogenetic analysis carried out clearly indicate that the obscura group is formed by, at least, four well-defined lineages that would have appeared as the consequence of a rapid phyletic radiation. Two of the lineages correspond to monophyletic subgroups (i.e., afftnis and pseudoobscura), whereas the obscura subgroup remains heterogeneous assemblage that could be reasonably subdivided into at least two complexes (i.e., subobscura and obscura).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173417
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  • 44
    Digitale Medien
    Digitale Medien
    Aspects of nonrandom turnover involved in the concerted evolution of intergenic spacers within the ribosomal DNA of Drosophila melanogaster (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 151-159 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Concerted evolution ; Molecular drive ; Drosophila ; rDNA spacers ; PCR length polymorphism ; MVR-PCR mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Polymerase chain reaction (PCR)-amplified, sequenced, and digitally typed intergenic spacers (IGSs) of the ribosomal (r)DNA in D. melanogaster reveal unexpected features of the mechanisms of turnover involved with the concerted evolution of the gene family. Characterization of the structure of three isolated IGS length variants reveals breakage “hot spots” within the 330-base-pair (bp) subrepeat array found in the spacers. Internal mapping of variant repeats within the 240-bp subrepeat array using a novel digital DNA typing procedure (minisatellite variant repeat [MVR]-PCR) shows an unexpected pattern of clustering of variant repeats. Each 240-bp subrepeat array consists of essentially two halves with the repeats in each half identified by specific mutations. This bipartite structure, observed in a cloned IGS unit, in the majority of genomic DNA of laboratory and wild flies and in PCR-amplified products, has been widely homogenized yet is not predicted by a model of unequal crossing over with randomly placed recombination breakpoints. Furthermore, wild populations contain large numbers of length variants in contrast to uniformly shared length variants in laboratory stocks. High numbers of length variants coupled to the observation of a homogenized bipartite structure of the 240-bp subrepeat array suggest that the unit of turnover and homogenization is smaller than the IGS and might involve gene conversion. The use of PCR for the structural analysis of members of the rDNA gene family coupled to digital DNA typing provides powerful new inroads into the mechanisms of DNA turnover affecting the course of molecular evolution in this family.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00163804
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  • 45
    Digitale Medien
    Digitale Medien
    Conservation of intron position indicates separation of major and variant H2As is an early event in the evolution of eukaryotes (1990)
    Springer
    Journal of molecular evolution 30 (1990), S. 449-455 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Histone H2A ; Histone variant ; Intron position ; Drosophila ; Tetrahymena
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Genomic clones ofDrosophila andTetrahymena histone H2A variants were isolated using the corresponding cDNA clones, (van Daal et al. 1988; White et al. 1988). The site corresponding to the initiation of transcription was defined by primer extension for bothDrosophila andTetrahymena genomic sequences. The sequences of the genomic clones revealed the presence of introns in each of the genes. TheDrosophila gene has three introns: one immediately following the initiation codon, one between amino acids 26 and 27 (gln and phe), and one between amino acids 64 and 65 (glu and val). TheTetrahymena gene has two introns, the positions of which are identical to the first two introns of theDrosophila gene. The chicken H2A.F variant gene has been recently sequenced and it contains four introns (Dalton et al. 1989). The first three of these are in the same positions as the introns in theDrosophila gene. The fourth intron interrupts amino acid 108 (gly). In all cases the sizes and the sequences of the introns are divergent. However, the fact that they are in conserved positions suggests that at least two of the introns were present in the ancestral gene. A phylogenetic tree constructed from the sequences of the variant and major cell cycle-regulated histone H2A proteins from several species indicates that the H2A variant proteins are evolutionarily separate and distinct from the major cell cycle-regulated histone H2A proteins. The ancestral H2A gene must have duplicated and diverged before fungi and ciliates diverged from the rest of the eukaryote lineage. In addition, it appears that the variant histone H2A proteins analyzed here are more conserved than the major histone H2A proteins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02101116
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  • 46
    Digitale Medien
    Digitale Medien
    TheAdh genomic region ofDrosophila ambigua: Evolutionary trends in different species (1991)
    Springer
    Journal of molecular evolution 32 (1991), S. 454-462 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Alcohol dehydrogenase gene ; Drosophila ; Gene structure ; Evolutionary trends ; Nucleotide substitution rate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The study of individual genes is essential to a comprehensive understanding of genome evolution. The wealth of information on alcohol dehydrogenase (Adh) inDrosophila makes this gene particularly suitable for such analysis. We have characterized more than 4 kb of the genomicAdh region inDrosophila ambigua and compared this region toDrosophila mauritiana andDrosophila pseudoobscura. The presence of two genes,Adh and 3′ORF (open reading frame), has been confirmed and some of their essential features have been inferred from primary structural analysis. Inter- and intraspecific comparisons have led us to support that both genes may have diverged from an ancient precursor. They appear to be evolving independently, and show a species-specific pattern. TheAdh in theobscura group species lacks amino acids three and four when compared to the species of themelanogaster group and has accumulated most of its amino acid replacements in the third exon. Neither characteristic is observed when any other group species are compared, which suggests that these may be particular features of the evolution of theobscura group. The 3′ORF is highly conserved among the three species analyzed, although variability in the length of the third exon and the nucleotide substitution rate, which is much higher than inAdh, are worth noting. According to our data, both mutation/fixation rates and the distribution of mutations vary over time, which makes it difficult to predict the evolutionary dynamics of specific genome regions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02102647
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  • 47
    Digitale Medien
    Digitale Medien
    Evidence for interspecific transfer of the transposable element mariner betweenDrosophila andZaprionus (1991)
    Springer
    Journal of molecular evolution 33 (1991), S. 514-524 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Zaprionus ; Mariner ; Transposable elements ; Horizontal gene transfer ; Alcohol dehydrogenase (Adh) ; Sequence divergence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The transposable element mariner occurs widely in themelanogaster species group ofDrosophila. However, in drosophilids outside of themelanogaster species group, sequences showing strong DNA hybridization with mariner are found only in the genusZaprionus. the mariner sequence obtained fromZaprionus tuberculatus is 97% identical with that fromDrosophila mauritiana, a member of themelanogaster species subgroup, whereas a mariner sequence isolated fromDrosophila tsacasi is only 92% identical with that fromD. mauritiana. BecauseD. tsacasi is much more closely related toD. mauritiana than isZaprionus, the presence of mariner inZaprionus may result from horizontal transfer. In order to confirm lack of a close phylogenetic relationship between the genusZaprionus and themelanogaster species group, we compared the alcohol dehydrogenase (Adh) sequences among these species. The results show that the coding region of Adh is only 82% identical betweenZ. tuberculatus andD. mauritiana, as compared with 90% identical betweenD. tsacasi andD. mauritiana. Furthermore, the mariner gene phylogeny obtained by maximum likelihood and maximum parsimony analyses is discordant with the species phylogeny estimated by using the Adh genes. The only inconsistency in the mariner gene phylogeny is in the placement of theZaprionus mariner sequence, which clusters with mariner fromDrosophila teissieri andDrosophila yakuba in themelanogaster species subgroup. These results strongly suggest horizontal transfer.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02102804
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  • 48
    Digitale Medien
    Digitale Medien
    Conservation and change of the developmentally crucial fushi tarazu gene in Drosophila (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 315-326 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Fushi tarazu ; Functional constraints ; Regulatory elements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have studied the evolutionary changes occurring in the noncoding regions around the developmentally important fushi tarazu (ftz) gene in a total of 11 species in the genus Drosophila. Previous molecular developmental studies have identified DNA elements both 3′ and 5′ to the coding region which are important in proper regulation of expression of the Drosophila melanogaster ftz gene. We show here that these same elements are the most evolutionarily conserved regions in the vicinity of the gene homologs. Parts of some control elements are more conserved than exonic sequences. Not only is there sequence conservation, but the relative position, orientation, and distances among the control elements remain conserved. One quite significant difference does exist between the two major subgenera studied, Sophophora and Drosophila: namely, an inversion of the ftz unit with respect to other genes in the Antennapedia complex, ANT-C. As a comparison, we applied similar analysis to a “housekeeping” gene-rosy (ry), or Xdh. In contrast, DNA sequences 5′ to the ry coding region revealed little evolutionary conservation. These studies bear out the proposition that functionally important DNA sequences remain more conserved through evolutionary time than do less functionally important sequences. This proposition could be tested in the present case because we could predict a priori from the developmental studies which DNA regions should be most conserved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00182179
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  • 49
    Digitale Medien
    Digitale Medien
    Degenerating gypsy retrotransposons in a male fertility gene on the Y chromosome of Drosophila hydei (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 452-465 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Y chromosome ; Male fertility genes ; Lampbrush loops ; Germ line ; Transposable elements ; Gypsy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract During the evolution of the Y chromosome of Drosophila hydei, retrotransposons became incorporated into the lampbrush loop pairs formed by several of the male fertility genes on this chromosome. Although insertions of retrotransposons are involved in many spontaneous mutations, they do not affect the functions of these genes. We have sequenced gypsy elements that are expressed as constituents of male fertility gene Q in the lampbrush loop pair Nooses. We find that these gypsy elements are all truncated and specifically lost those sequences that may interfere with the continuity of lampbrush loop transcription. Only defective coding regions are found within the loop. Gypsy is not transcribed in loops of many other Drosophila species harboring the family. These results suggest that any contribution of gypsy to the function of male fertility gene Q does not depend on a conserved DNA sequence.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173414
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  • 50
    Digitale Medien
    Digitale Medien
    Visual control of wing beat frequency in Drosophila (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 587-596 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Wing beat frequency ; Optomotor responses ; Landing response ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The present study shows that the wing beat frequency of Drosophila is visually controlled and modulated in response to different optomotor stimuli. Whereas rotational large field stimuli do not appear to modulate wing beat frequency, single rotating vertical stripes increase or decrease wing beat frequency when moving back-to-front or front-to-back, respectively. Maximal modulations occur at lateral stripe positions. Expansion stimuli eliciting the landing response cause a marked increase in wing beat frequency. Parameters of this frequency response depend in a graded fashion on certain stimulus properties, and the frequency response co-habituates with the landing response. Several results indicate that the frequency response is an integral component of the landing response, although it can also occur when the characteristic front leg extension is not observed. The complex spatial input integration underlying the frequency response and other motor components of the landing response cannot easily be explained by a system of large field integration units, but might indicate the existence of local expansion detectors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00199480
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  • 51
    Digitale Medien
    Digitale Medien
    Wavelength-dependent effects of light on magnetic compass orientation in Drosophila melanogaster (1993)
    Springer
    Journal of comparative physiology 172 (1993), S. 303-308 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Drosophila ; Photoreception ; Magnetoreception ; Magnetic compass orientation ; Geomagnetic field
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract 1. Wildtype Oregon-R Drosophila melanogaster were trained in the ambient magnetic field to a horizontal gradient of 365 nm light emanating from one of the 4 cardinal compass directions and were subsequently tested in a visually-symmetrical, radial 8-arm maze in which the magnetic field alignment could be varied. When tested under 365 nm light, flies exhibited consistent magnetic compass orientation in the direction from which light had emanated in training. 2. When the data were analyzed by sex, males exhibited a strong and consistent magnetic compass response while females were randomly oriented with respect to the magnetic field. 3. When tested under 500 nm light of the same quantal flux, females were again randomly oriented with respect to the magnetic field, while males exhibited a 90° clockwise shift in magnetic compass orientation relative to the trained direction. 4. This wavelength-dependent shift in the direction of magnetic compass orientation suggests that Drosophila may utilize a light-dependent magnetic compass similar to that demonstrated previously in an amphibian. However, the data do not exclude the alternative hypothesis that a change in the wavelength of light has a non-specific effect on the flies' behavior, i.e., causing the flies to exhibit a different form of magnetic orientation behavior.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00216612
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  • 52
    Digitale Medien
    Digitale Medien
    Improved stability of Drosophila larval neuromuscular preparations in haemolymph-like physiological solutions (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 179-191 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Drosophila ; Neuromuscular ; Haemolymph ; Membrane potential ; Synaptic potential
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Neuromuscular preparations from third instar larvae of Drosophila are not well-maintained in commonly used physiological solutions: vacuoles form in the muscle fibers, and membrane potential declines. These problems may result from the Na∶K ratio and total divalent cation content of these physiological solutions being quite different from those of haemolymph. Accordingly haemolymph-like solutions, based upon ion measurements of major cations, were developed and tested. Haemolymph-like solutions maintained the membrane potential at a relatively constant level, and prolonged the physiological life of the preparations. Synaptic transmission was well-maintained in haemolymph-like solutions, but the excitatory synaptic potentials had a slower time course and summated more effectively with repetitive stimulation, than in standard Drosophila solutions. Voltage-clamp experiments suggest that these effects are linked to more pronounced activation of muscle fiber membrane conductances in standard solutions, rather than to differences in passive muscle membrane properties or changes in postsynaptic receptor channel kinetics. Calcium dependence of transmitter release was steep in both standard and haemolymph-like solutions, but higher external calcium concentrations were required for a given level of release in haemolymph-like solutions. Thus, haemolymph-like solutions allow for prolonged, stable recording of synaptic transmission.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00215114
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  • 53
    Digitale Medien
    Digitale Medien
    Altered mechanoreceptor response in Drosophila bang-sensitive mutants (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 267-278 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Drosophila ; Bang sensitivity ; Mechanotransduction ; Adaptation ; Sensory coding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Bang-sensitive mutants of Drosophila melano gaster (bas 1, bssMW1, eas2, tko25t) display seizure followed by paralysis when subjected to mechanical shock. However, no physiological or biochemical defect has been found to be common to all of these mutants. In order to observe the effects of bang-sensitive mutations upon an identified neuron, and to study the nature of mechanically induced paralysis, we examined the response of a mechanosensory neuron in these mutants. In each single mutant and the double mutant bas 1 bssMW1, the frequency of action potentials in response to a bristle displacement was reduced. This is the first demonstration of a physiological defect common to several of the bang-sensitive mutations. Adaptation of spike frequency, cumulative adaptation to repeated stimulation (fatigue) and the time course of recovery from adaptation were also examined. Recovery from adaptation to a conditioning stimulus was examined in two mutants (bas 1 and bss MW1), and initial recovery from adaptation was greater in both mutants. Quantification of receptor potentials was complicated by variability inherent in extracellular recording conditions, but examination of the waveform and range of amplitudes did not indicate clear mutant defects. Therefore the differences observed in the spike response may be due to an alteration of the transfer from receptor potentials to action potential production. DNA sequence analysis of tko and eas has indicated that they encode apparently unrelated biochemical products. Our results suggest that these biochemical lesions lead to a common physiological defect in mechanoreceptors. Although this defect does not provide a straightforward explanation for bang sensitivity, the altered cellular process may lead to bang sensitivity through its action in different parts of the nervous system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192986
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  • 54
    Digitale Medien
    Digitale Medien
    Length polymorphism in the threonine-glycine-encoding repeat region of theperiod gene inDrosophila (1991)
    Springer
    Journal of molecular evolution 32 (1991), S. 238-246 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; per gene ; Repeated sequence ; Threonine-glycine ; Length polymorphism ; Minisatellite
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Single-fly polymerase chain reaction amplification and direct DNA sequencing revealed high levels of length polymorphism in the threonine-glycine encoding repeat region of theperiod (per) gene in natural populations ofDrosophila melanogaster. DNA comparison of two alleles of identical lengths gave a high number of synonymous substitutions suggesting an ancient time of separation. However detailed examination of the sequences of different Thr-Gly length variants indicated that this divergence could be understood in terms of four deletion/insertion events. InDrosophila pseudoobscura a length polymorphism is observed in a five-amino acid degenerate repeat, which corresponds tomelanogaster's Thr-Gly domain. In spite of the differences betweenD. melanogaster andD. pseudoobscura in the amino acid sequence of the repeats, the predicted secondary structures suggest evolutionary and mechanistic constraints on theper protein of these two species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02342746
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  • 55
    Digitale Medien
    Digitale Medien
    Gypsy homologous sequences inDrosophila subobscura (gypsyDS) (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 127-135 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Transposable elements ; Drosophila ; Gypsy ; Horizontal transfer ; In situ hybridization ; Molecular evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Characterization of sequences homologous to theDrosophila melanogaster gypsy transposable element was carried out inDrosophila subobscura (gypsyDS). They were found to be widely distributed among natural populations of this species. From Southern blot and in situ analyses, these sequences appear to be mobile in this species.GypsyDS sequences are located in both euchromatic and heterochromatic regions. A completegypsyDS sequence was isolated from aD. subobscura genomic library, and a 1.3-kb fragment which aligns with the ORF2 of theD. melanogaster gypsy element was sequenced. Comparisons of this sequence in three species (D. subobscura, D. melanogaster, and D. virilis) indicate that there is greater similarity between theD. subobscura-D. virilis sequences than betweenD. subobscura andD. melanogaster. Molecular divergence ofgypsy sequences betweenD. virilis andD. subobscura is estimated at 16 MY, whereas the most likely divergence time of these two species is more than 60 MY. These data strongly suggest thatgypsy sequences have been horizontally transferred between these species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00166248
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  • 56
    Digitale Medien
    Digitale Medien
    Characterization of the length polymorphism in the A+T-rich region of the Drosophila obscura group species (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 214-223 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Mitochondrial DNA ; Length polymorphisms ; A+T-rich region ; Tandem duplicated sequences ; Nucleotide sequences ; Secondary structures
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In the twelve Drosophila obscura group species studied, belonging to the affinis, obscura, and pseudoobscura subgroups, the mitochondrial DNA length ranges from 15.8 to 17.2 kb. This length polymorphism is mainly due to insertions/deletions in the variable region of the A+T-rich region. In addition, one species (D. tristis) possess a tandem duplication of a 470-bp fragment that contains the replication origin. The same duplication has occurred at least twice in the Drosophila evolutionary history due to the fact that the repetition is analogous to repetitions found in the four species of the D. melanogaster complex. By comparing the nucleotide sequence of the conserved region in D. ambigua, D. obscura, D. yakuba, D. teissieri, and D. virilis, we show the presence of a secondary structure, likely implied in the replication origin, which could favor the generation of this kind of duplications. Finally, we propose that the high A and T content in the variable region of the A + T-rich region favors the formation of less-stable secondary structures, which could explain the generation of minor insertion/deletions found in this region.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160476
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  • 57
    Digitale Medien
    Digitale Medien
    Extreme rates and heterogeneity in insect DNA evolution (1990)
    Springer
    Journal of molecular evolution 30 (1990), S. 273-280 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Genome evolution ; Molecular evolutionary rates ; Insect DNA ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary DNA-DNA hybridization studies of insects, more specificallyDrosophila and cave crickets, have revealed interesting patterns of genome evolution that contrast markedly with what has been seen in other taxa, especially mammals and birds. Insect genomes are composed of sections of single-copy DNA with extreme variation in rates of evolutionary change. This variation is more extreme than between introns and exons; introns fall into the relatively conserved fraction of the genome. Attempts to calculate absolute rates of change inDrosophila DNA have all led to estimates some 5–10 times faster than those found in most vertebrates; this is true even for the more conservative part of the nuclear genome. Finally we point out that morphological similarity, chromosomal similarity, and/or ability to form interspecific hybrids is often associated with quite high levels of single-copy DNA divergence in insects as compared to mammals and birds.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02099997
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  • 58
    Digitale Medien
    Digitale Medien
    Speciation in the Artemia genus: Mitochondrial DNA analysis of bisexual and parthenogenetic brine shrimps (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 156-168 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Artemia franciscana ; Artemia salina ; Artemia parthenogenetica ; Mitochondrial DNA evolution ; Cytochrome c oxidase I ; Cytochrome b ; Drosophila ; Arthropods ; Parthenogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract From the cloned mitochondrial DNAs (mtDNAs) isolated from two bisexual species, one Mediterranean, Artemia salina, and one American, Artemia franciscana, and two parthenogenetic (diploid and tetraploid) strains of Artemia parthenogenetica collected in Spain, physical maps have been constructed and compared. They are extremely different among themselves, much more than the differences between Drosophila melanogaster and D. yakuba and in the same range of different mammalian species such as mouse/rat or man/cow. The nucleotide sequences of two regions of mtDNA encoding parts of the cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) genes have been determined in the two bisexual species and the two parthenogenetic strains. Comparisons of these sequences have revealed a high degree of divergence at the nucleotide level, averaging more than 15%, in agreement with the differences found in the physical maps. The majority of the nucleotide changes are silent and there is a strong bias toward transitions, with the C↔T substitutions being highly predominant. The evolutionary distance between the two Artemia parthenogenetica is high and there is no clear relationship with any of the bisexual species, including the one present nowadays in Spain. Using a combination of molecular (mtDNA) and morphological markers it is possible to conclude that all of these Artemia isolates should be actually considered as belonging to different species, even the two Artemia parthenogenetica diploidica and tetraploidica.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00166162
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  • 59
    Digitale Medien
    Digitale Medien
    Interspecific sequence comparison of the muscle-myosin heavy-chain genes from Drosophila hydei and Drosophila melanogaster (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 357-368 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Muscle-myosin heavy-chain gene ; Alternative exons ; Synonymous substitutions ; Amino acid substitutions ; Evolution ; Testis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The muscle-myosin heavy-chain (mMHC) gene of Drosophila hydei has been sequenced completely (size 23.3 kb). The sequence comparison with the D. melanogaster mMHC gene revealed that the exonintron pattern is identical. The protein coding regions show a high degree of conservation (97%). The alternatively spliced exons (3a-b, 7a-d, 9a-c, 11a-e, and 15a-b) display more variations in the number of nonsynonymous and synonymous substitutions than the common exons (2, 4, 5, 6, 8, 10, 12, 13, 14, 16, 17, and 19). The base composition at synonymous sites of fourfold degenerate codons (third position) is not biased in the alternative exons. In the common exons there exists a bias for C and against A. These findings imply that the alternative exons of the Drosophila mMHC gene evolve at a different, in several cases higher, rate than the common ones. The 5′ splice junctions and 5′ and 3′ untranslated regions show a high level of similarity, indicating a functional constraint on these sequences. The intron regions vary considerably in length within one species, but the corresponding introns are very similar in length between the two species and all contain stretches of sequence similarity. A particular example is the first intron, which contains multiple regions of similarity. In the conserved regions of intron 12 (head-tail border) sequences were found which have the potential to direct another smaller mMHC transcript.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160268
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  • 60
    Digitale Medien
    Digitale Medien
    Functional conservation of a glucose-repressible amylase gene promoter from Drosophila virilis in Drosophila melanogaster (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 234-242 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Glucose repression ; Amylase gene ; Interspecific promoter function ; Conserved cis-acting elements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Previous studies have demonstrated that the expression of the α-amylase gene is repressed by dietary glucose in Drosophila melanogaster. Here, we show that the α-amylase gene of a distantly related species, D. virilis, is also subject to glucose repression. Moreover, the cloned amylase gene of D. virilis is shown to be glucose repressible when it is transiently expressed in D. melanogaster larvae. This cross-species, functional conservation is mediated by a 330-bp promoter region of the D. virilis amylase gene. These results indicate that the promoter elements required for glucose repression are conserved between distantly related Drosophila species. A sequence comparison between the amylase genes of D. virilis and D. melanogaster shows that the promoter sequences diverge to a much greater degree than the coding sequences. The amylase promoters of the two species do, however, share small clusters of sequence similarity, suggesting that these conserved cis-acting elements are sufficient to control the glucose-regulated expression of the amylase gene in the genus Drosophila.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160478
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  • 61
    Digitale Medien
    Digitale Medien
    Nucleotide divergence of the rp49 gene region between Drosophila melanogaster and two species of the Obscura group of Drosophila (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 243-248 
    Details
    ISSN: 1432-1432
    Schlagwort(e): rp49 gene ; Drosophila ; Sequence divergence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A 2.1-kb SStI fragment including the rp49 gene and the 3′ end of the δ-serendipity gene has been cloned and sequenced in Drosophila pseudoobscura. rp49 maps at region 62 on the tip of chromosome II of this species. Both the coding and flanking regions have been aligned and compared with those of D. subobscura. There is no evidence for heterogeneity in the rate of silent substitution between the rp49 coding region and the rate of substitutions in flanking regions, the overall silent divergence per site being 0.19. Noncoding regions also differ between both species by different insertions/deletions, some of which are related to repeated sequences. The rp49 region of D. pseudoobscura shows a strong codon bias similar to those of D. subobscura and D. melanogaster. Comparison of the rates of silent (K S ) and nonsilent (K a ) substitutions of the rp49 gene and other genes completely sequenced in D. pseudoobscura and D. melanogaster confirms previous results indicating that rp49 is evolving slowly both at silent and nonsilent sites. According to the data for the rp49 region, D. pseudoobscura and D. subobscura lineages would have diverged some 9 Myr ago, if one assumes a divergence time of 30 Myr for the melanogaster and obscura groups.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160479
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  • 62
    Digitale Medien
    Digitale Medien
    Evolution of regulatory genes and patterns: Relationships to evolutionary rates and to metabolic functions (1993)
    Springer
    Journal of molecular evolution 37 (1993), S. 590-599 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Gene regulation ; Drosophila ; Adaptation ; Enzymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In an effort to understand the forces shaping evolution of regulatory genes and patterns, we have compared data on interspecific differences in enzyme expression patterns among the rapidly evolving Hawaiian picture-winged Drosophila to similar data on the more conservative virilis species group. Divergence of regulatory patterns is significantly more common in the former group, but cause and effect are difficult to discern. Random fixation of regulatory variants in small populations and/or during speciation may be somewhat more likely than divergence driven by selection. Within the picture-winged group, we also have compared enzymes that fulfill different metabolic roles. There are highly significant differences between individual enzymes, but no obvious correlations to functional categories.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00182745
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  • 63
    Digitale Medien
    Digitale Medien
    Nucleotide sequence of the genomic region encompassing Adh and Adh-Dup genes of D. lebanonensis (Scaptodrosophila): Gene expression and evolutionary relationships (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 455-467 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Alcohol dehydrogenase ; Drosophila ; Drosophila lebanonensis ; Gene expression ; Codon usage ; Phylogenetic relationships
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The region of the genome of D. lebanonensis that contains the Adh gene and the downstream Adh-dup gene was sequenced. The structure of the two genes is the same as has been described for D. melanogaster. Adh has two promoters and Adh-dup has only one putative promoter. The levels of expression of the two genes in this species are dramatically different. Hybridizing the same Northern blots with a specific probe for Adh-dup, we did not find transcripts for this gene in D. lebanonensis. The level of Adh distal transcript in adults of D. lebanonensis is five times greater than that of D. melanogaster adults. The maximum levels of proximal transcript are attained at different larval stages in the two species, being three times higher in D. melanogaster late-second-instar larvae than in D. lebanonensis first-instar larvae. The level of Adh transcripts allowed us to determine distal and proximal initiation transcription sites, the position of the first intron, the use of two polyadenylation signals, and the heterogeneity of polyadenylation sites. Temporal and spatial expression profiles of the Adh gene of D. lebanonensis show qualitative differences compared with D. melanogaster. Adh and Adh-dup evolve differently as shown by the synonymous and nonsynonymous substitution rates for the coding region of both genes when compared across two species of the melanogaster group, two of the obscura group of the subgenus Sophophora and D. lebanonensis of the victoria group of the subgenus Scaptodrsophila. Synonymous rates for Adh are approximately half those for Adh-dup, while nonsynonymous rates for Adh are generally higher than those for Adh-dup. Adh shows 76.8% identities at the protein level and 70.2% identities at the nucleotide level while Adh-dup shows 83.7% identities at the protein level and 67.5% identities at the nucleotide level. Codon usage for Adh-dup is shown to be less biased than for Adh, which could explain the higher synonymous rates and the generally lower nonsynonymous substitution rates in Adh-dup compared with Adh. Phylogenetic trees reconstructed by distance matrix and parsimony methods show that Sophophora and Scaptodrosophila subgenera diverged shortly after the separation from the Drosophila subgenus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00178845
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  • 64
    Digitale Medien
    Digitale Medien
    Drive-selection equilibrium: Homopolymer evolution in the Drosophila gene mastermind (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 637-641 
    Details
    ISSN: 1432-1432
    Schlagwort(e): mastermind ; Drosophila ; Homopolymer ; Repeat length variation ; Molecular drive ; Natural selection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Interspecific sequence comparison of the highly repetitive Drosophila gene mastermind (mam) reveals extensive length variation in homopolymer domains. The length variation in homopolymers is due to nucleotide misalignment in the underlying triplet repeats, which can lead to slippage mutations during DNA replication or repair. In mam, the length variation in repetitive regions appears to be balanced by natural selection acting to maintain the distance between two highly conserved charge clusters. Here we report a statistical test of the null hypothesis that the similarity in the amino acid distance between the charge clusters of each species arose by chance. The results suggest that at mam there is a juxtaposition of length variability due to molecular drive and length conservation maintained by natural selection. The analysis of mam allows the extension of current theories of drive-selection interaction to encompass homopolymers. Our model of drive-selection equilibrium suggests that the physical flexibility, length variability, and abundance of homopolymer domains provide an important source of genetic variation for natural populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00175884
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  • 65
    Digitale Medien
    Digitale Medien
    Olfactory physiology in the Drosophila maxillary palp requires the visual system gene rdgB (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 687-693 
    Details
    ISSN: 1432-1351
    Schlagwort(e): rdgB ; Maxillary palp ; Drosophila ; Electrophysiology ; Olfaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract We describe the kinetics of odorant response in the maxillary palp of Drosophila, and show that the rate of recovery from odorant stimulation is affected by mutation of the rdgB (retinal degeneration B) gene. We use immunocytochemistry to confirm that the rdgB gene product is expressed in the maxillary palp. rdgB has recently been shown to encode a protein with Ca2+-binding sites and sequence similarity to rat brain phosphatidylinositol transfer protein; it is located near the rhabdomeric membranes in photoreceptor cells, where it has been suggested to play a role in membrane transport. The delay in recovery kinetics that we observe in olfactory tissue may reflect a defect in membrane restoration at the conclusion of the olfactory transduction cascade. The use of common molecules in the physiology of two olfactory organs, and in both visual and olfactory physiology, is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00191841
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  • 66
    Digitale Medien
    Digitale Medien
    Quantifying relative importance of maxillary palp information on the olfactory behavior of Drosophila melanogaster (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 761-766 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Olfactory behavior ; Antenna ; Maxillary palp ; Olfaction ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Maxillary palps have been proposed as secondary olfactory organs, after the antennae, in Drosophila melanogaster. Our study tries to establish the quantitative importance of both organs as olfactory information mediators. Dose-response curves for three odorants: ethyl acetate, propionaldehyde and benzaldehyde were carried out for comparing olfaction in either complete animals or flies surgically deprived of antennae. Antennaless flies tested in our behavioral assay showed indifferent, attractant and repellent responses depending on concentration, similarly as normal flies do. However, they clearly displayed less sensitivity than normal flies. The range of concentrations they were able to perceive was correlated to antennal sensitivity approximately by a factor 1∶10 for ethyl acetate and benzaldehyde, and between 1∶10 and 1∶100 at high concentrations of propionaldehyde. A complementary experiment was performed to test changes in olfactory behavior produced by removing maxillary palps in the presence of antennae. At high concentrations of odorant, responses to ethyl acetate and propionaldehyde experienced small changes when both palps were removed. Results are compatible with a summation model of all olfactory information reaching the brain either through antennae or palps.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00191847
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  • 67
    Digitale Medien
    Digitale Medien
    Determination of phosphorus, sulfur and chlorine in high-purity aluminium (1990)
    Springer
    Microchimica acta 101 (1990), S. 273-279 
    Details
    ISSN: 1436-5073
    Schlagwort(e): aluminium analysis ; phosphorus ; sulfur ; chlorine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Multi-step procedures for the determination of phosphorus, sulfur and chlorine are described and tested against established methods and on reference materials. Phosphorus is separated as hydrogen phosphide, extracted as phosphomolybdic acid, reduced to molydenum blue and measured photometrically (detection limit 0.05 μg/g). Sulfur is separated after reduction as hydrogen sulfide or by means of pyrohydrolysis and measured by ICP-OES (detection limit 0.1 μg/g). Chloride can be measured by ion chromatography after pyrohydrolytic separation (detection limit 0.1 μg/g). The determination of sulfur was also successfully tested on copper and steel samples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01244179
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  • 68
    Digitale Medien
    Digitale Medien
    The determination of phosphonate base scale inhibitors in brines by plasma spectrometry (1992)
    Springer
    Microchimica acta 109 (1992), S. 201-209 
    Details
    ISSN: 1436-5073
    Schlagwort(e): phosphonate base scale inhibitor ; brine ; direct current plasma ; inductively coupled plasma atomic emission spectrometry ; phosphorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The determination of phosphonate base scale inhibitors in brines by direct current plasma (DCP) and inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. The first method is based on a direct nebulization of the brine samples and plasma using the phosphorus line at 213.618 nm. The second method involves extraction of phosphorus as phospho-antimonyl molybdate complex into methylisobutyl ketone (MIBK) phase and analysis of the extract for molybdenum using the Mo 313.260 nm line. Comparison between the proposed methods and an established recommended method [1] shows excellent agreement between the results in addition to the sensitivity and ease of automation provided by AES.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01242475
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  • 69
    Digitale Medien
    Digitale Medien
    Historical changes in sediments of Pyramid Lake, Nevada, USA: consequences of changes in the water balance of a terminal desert lake (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 87-101 
    Details
    ISSN: 1573-0417
    Schlagwort(e): Great Basin ; climatic variations ; productivity ; organic matter ; nitrogen ; phosphorus ; hardwater lake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO3 and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO3 content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00678089
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  • 70
    Digitale Medien
    Digitale Medien
    Charophyta: their use in paleolimnology (1994)
    Springer
    Journal of paleolimnology 10 (1994), S. 43-52 
    Details
    ISSN: 1573-0417
    Schlagwort(e): Charophyta ; evolution ; gyrogonite morphology ; ecology-paleoecology ; Argentina ; South America
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract Charophyta are common algae in limnic waters from many regions and are an interesting group from an evolutionary point-of-view, as they are believed to be related to the Chlorophyceae and land plants. Paleontological-botanical systematics are discussed, taking into consideration some new advances. Charophytes live in all types of inland waters and are sensitive to ecological change, and so they are very useful paleolimnological markers. Gaps concerning gyrogonite morphology in extant taxa and their responses to different environmental conditions must be described. This paper discusses data concerning ecological factors affecting the distribution of Argentinian Charophyta (principally distributed between 30°S and 40°S), gyrogonite morphology related to different ecological conditions, and the way that Charophyta can modify the environment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00683145
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  • 71
    Digitale Medien
    Digitale Medien
    Pleistocene Charophyta from Arroyo Perucho Verna, Province of Entre Rios, Argentina (1994)
    Springer
    Journal of paleolimnology 10 (1994), S. 53-58 
    Details
    ISSN: 1573-0417
    Schlagwort(e): Charophyta ; evolution ; gyrogonite morphology ; ecology-paleoecology ; Argentina ; South America
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract The Pleistocene charophytes from Arroyo Perucho Verna, Province of Entre Ríos, were analyzed.Chara contraria Br. ex Kütz.,C. contraria var.longilinea Cáceres,C. globularis Thuill. andTolypella intricata (Trent. ex Roth.) Leonh. var.apiculata (A. Br.) Wood were described and illustrated with scanning electron microscope. The assemblage indicates fresh alkaline to slightly saline waters, not very deep, in a lentic or sometimes lotic environment. Extant assemblages provide data for this paleoecological reconstruction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00683146
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  • 72
    Digitale Medien
    Digitale Medien
    Hydrology of the Peel-Harvey estuary catchment (1993)
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 127-133 
    Details
    ISSN: 1573-0867
    Schlagwort(e): hydrology ; water balance ; phosphorus ; Streamflow ; Peel-Harvey
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract This paper discusses the land types, hydrologic characteristics and processes, and the major modification of these, in relation to mechanisms and magnitude of phosphorus losses to drains and riverine systems which discharge to the Peel-Harvey estuary. About 75% of the coastal plain part of the catchment is cleared of native vegetation and used for dryland, dairy and beef grazing. There are small areas devoted to irrigated pasture and commercial horticulture. Seventy-five percent of the soils of the catchment are sandy surfaced with a poor capacity to retain phosphorus. Though the area is flat, catchment water yields are high because of a large winter rainfall excess and low soil storage capacity. Drainage schemes have been constructed in much of the catchment to remove excess water quickly. This was required initially to allow agricultural expansion and is now important for protecting a growing infrastructure which serves the most populous region of Western Australia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00747583
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  • 73
    Digitale Medien
    Digitale Medien
    Environmental impact of fertilizing soils by using sewage and animal wastes (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 1-22 
    Details
    ISSN: 1573-0867
    Schlagwort(e): animal slurries and manures ; applications to soils ; carbon- ; nitrogen- ; phosphorus ; contamination ; crop production ; dissemination ; hazardous organics ; heavy metals ; inputs ; macro- and micronutrients ; pathogens ; sewage sludges ; survival- ; transfer- ; transport and adsorption rates in soils
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The European Community is producing annually about 300 × 106 tons of sewage sludges as well as about 150, 950,160 and 200 tons of domestic, agricultural, industrial and other wastes (street litter, dead leaves etc.). About 20–25% of the German sewage sludges, which contain in average about 3.8,1.6, 0.4, 0.6, 5.3% DM−1 N, P, K, Mg and Ca, 202, 5, 131, 349, 53, 3 and 1446 mg kg−1 DM Pb, Cd, Cr, Cu, Ni, Hg, Zn as well as ca. 37 and 5 mg kg−1 Dm polychlorinated hydrocarbons and biphenyls, are recycled annually as fertilizer. In addition environmental impacts on the arable land of Germany may derive from 76,19.2, 64.7, 33.6, 7.8 and 0.1 kg ha−1 a−1 of N, P, K, Ca, Mg and Cu added as animal manures. Besides heavy metals and hazardous organics pathogens are disseminated with organic wastes. Crop production and soil fertility generally profit from the considerable amounts of plant nutrients and carbon in sewage sludges, animal slurries and manures, but the physicochemical soil properties, the composition of microbial, faunal and plant communities as well as the metabolic processes in the soil-, rhizo- and phyllosphere are changed by organic manuring. Consequences for the soil carbon-, nitrogen-and phosphorus-cycle are discussed. Impacts of heavy metals and hazardous organics on the soil biomass and its habitat as well as on transport mechanisms and surival times of disseminated pathogens in soils are reviewed with emphasis on the German situation. A proposal for future strategies (landscape recycling) is made.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00750669
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  • 74
    Digitale Medien
    Digitale Medien
    Results and experiences from fertilization experiments in The Netherlands (1991)
    Springer
    Nutrient cycling in agroecosystems 27 (1991), S. 107-111 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Liming ; phosphorus ; heathland ; copper ; fertilization ; forest
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Forest fertilization in the Netherlands has played an important role in the phase of afforestation of former heathlands. Research started in the early fifties, but results were not applied in practical forestry. A review is presented on forest fertilization in practice, and on the main results of the activities of De Dorschkamp on NPK fertilization, liming and micronutrients application. Attention is paid to problems which have developed during the past ten years.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01048613
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  • 75
    Digitale Medien
    Digitale Medien
    Share of agriculture in nitrogen and phosphorus emissions into the surface waters of Western Europe against the background of their eutrophication (1990)
    Springer
    Nutrient cycling in agroecosystems 26 (1990), S. 253-269 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Nitrogen ; phosphorus ; sulphur ; nutrient balances ; surface waters ; North Sea ; Baltic Sea ; eutrophication ; hypertrophication ; primary production
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Dissolved inorganic nitrogen and phosphorus, their relationship to each other (DIN/DIP) as predisposing (nutrient) factors, as well as prevailing weather as a triggering factor all work together to induce the primary production and hence the eutrophication (hypertrophication) process in surface waters. Sulfate likewise is a decisive predisposing factor influencing the eutrophication process by reducing N availability but increasing P availability and thus acting towards an N limitation of the primary production. This is one of the reasons why marine (coastal) waters and estuaries often exhibit N limitation with respect to primary production, while freshwater ecosystems often tend to exhibit P limitation. Within the N and P balance of agriculture of some countries of Western Europe (Netherlands, Denmark, Switzerland, FRG, UK and Sweden for N, resp. Netherlands, FRG and GDR for P) more the level than the efficiency of the N and P applications indicates the extent of the nutrient surplus. Despite 59–73% N utilization in plant production, the rate of 13–23% for agriculture as a whole equals to the 12–21% efficiency of N use in animal production. The varying N surplus in agriculture in the separate countries of 124 to 465 kg N ha−1 a−1 is determined almost exclusively by the level of the N application and not by its efficiency. The situation is similar for P: In spite of P utilization in plant production of 59–76%, P utilization in total agriculture is only 11–38%, or comparable to the P efficiency within animal production of 10–34%. The differing P excess balance of 55 to 88 kg P2O5 ha−1 a−1 is influenced by the level of the P application. The N and P efficacy of total agriculture hence is determined almost completely by that of animal production, since 83–95% (N basis) and 76–94% (P basis) of the total plant production (on top of the nationally varying levels of N and P use via imported feeds) are fed to animals — with the low N and P utilization cited above. Agriculture's share of the N and P emissions into surface water of several countries/regions in Western Europe (FRG, Netherlands, Italy, Denmark, Switzerland, Norway) ranges from 37 to 82% resp. 27 to 38%. Its share in the flus into the North Sea catchment basin will be about 60% for N and 25% for P related only to the anthropogenic material carried by the rivers. Agriculture's share in the atmospheric N emissions into the North and Baltic Seas can be estimated at about 65% or 55%, resp. while the remaining approx. 35% or 45%, resp. are traceable primarily to anthropogenic burning processes. For agriculture the priority lies in limiting N emissions into surface water caused by leaching, erosion and NH3 emissions, and reducing P emissions mainly through soil conservation (protection against erosion) and water protection. As regards N this means a demand for comprehensive protection of groundwater and atmosphere differentiated according to the potential for losses or the risk of losses on a site, also outside the protection zones. As regards P only those areas can be included in the demand for reduction of emissions that are actually threatened by erosion or surface runoff. Plenty of short-term and long-term measures are available to agriculture to reduce N and P emissions. Especially the long-range measures (such as creating nutrient balances on farms and fields, the integration of animal and plant production, maintaining maximum livestock densities according to the ability of areas to absorb nutrients, altered feeding programs in animal nutrition, changes in livestock keeping (slurry→deep litter), increasing the internal and external recycling of N and P) are capable of bringing about a satisfactory degree of success within the next 20 to 30 years.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01048764
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  • 76
    Digitale Medien
    Digitale Medien
    Land application of poultry litter and water quality in Oklahoma, U.S.A. (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 165-173 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Animal manure ; eutrophication ; ground water ; nitrogen ; phosphorus ; surface runoff
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract With the rapid growth of the poultry industry in Oklahoma, U.S.A., more litter is applied to farm land. Thus, information is required on the impact of applications on regional soil and water resources. The effect of soil and poultry litter management on nitrogen (N) and phosphorus (P) loss in runoff and subsurface flow from four 16 m2 plots (Ruston fine sandy loam, 6 to 8% slope) was investigated under natural rainfall. Plots under Bermudagrass (Cynodon dactylon) received 11 Mg litter ha−1, which amounts to contributions of approximately 410 kg N and 140 kg P ha−1 yr−1. In spring, litter was broadcast on 3 of the plots; the upper half of one and total area of the other two. One of the total-area broadcast plots was tilled to 6 cm, the other remained as no till. The fourth plot served as a control. Relative to the control, litter application increased mean concentrations of total N and total P in runoff during the 16-week study for no-till (15.4 and 5.8 mg L−1) and tilled treatments (16.7 and 6.1 mg L−1). However, values for the half-area application (5.6 and 2.0 mg L−1) were similar to the control (5.7 and 1.3 mg L−1). Interflow (subsurface lateral flow at 70 cm depth) P was not affected by litter application; however, nitrate-N concentrations increased from 0.6 (control) to 2.9 mg L−1 (no till). In all cases, 〈 2 % litter N and P was lost in runoff and interflow, maintaining acceptable water quality concentrations. Although litter increased grass yield (8518 kg ha−1) compared to the control (3501 kg ha−1), yields were not affected by litter management. An 8-fold increase in the plant available P content of surface soil indicates long-term litter management and application rates will be critical to the environmentally sound use of this nutrient resource.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00750462
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  • 77
    Digitale Medien
    Digitale Medien
    Response of ensete (Ensete ventricosum W.) to mineral fertilizers in southwest Ethiopia (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 107-113 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Ensete ventricosum ; fertilizer response ; nitrogen ; phosphorus ; potassium ; sulphur ; starch
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Ensete (Ensete ventricosum W. Cheesm.) is a root crop which stores starch in the root and in the lower part of the stem. It is grown in the southwest of Ethiopia and due to its drought resistance, it is of outstanding importance for the supply of food to the local population. Until now virtually nothing is known about the response of Ensete to fertilizer application. Field trials carried out on three representative soils in Ethiopia showed that Ensete biomass yields were increased significantly on all three soils by nitrogen and phosphorus application. Potassium had only marginal effect on biomass growth but favourably influenced starch production. Sulfate application had no major impact on growth and starch yield. The yield response was well related to the level of available nutrients in the soil, as determined by electroultrafiltration (EUF). Leaf analysis provided preliminary evidence that optimum levels of N, P, and K may be 3.8%, 0.3%, and 4.8%, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00748551
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  • 78
    Digitale Medien
    Digitale Medien
    Fertilization of millet cv. Souna III in Senegal: dry matter production and nutrient uptake (1993)
    Springer
    Nutrient cycling in agroecosystems 35 (1993), S. 217-226 
    Details
    ISSN: 1573-0867
    Schlagwort(e): calcium ; dry matter distribution ; fertilizer ; harvest index ; magnesium ; manure ; millet ; nitrogen ; nutrient uptake ; phosphorus ; potassium ; Senegal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract In a fertilizer and manure experiment, millet was grown under four treatments (no fertilizer or manure, farmyard manure, chemical fertilizer, and both). Grain yield and total aboveground biomass production of the unfertilized plot were relatively high. The observed differences in total dry matter production must be attributed to differences in nutrient availability, as amount of rainfall and its distribution were favourable. Results show only small differences in distribution of dry matter among the various plant organs between the best and the non-fertilized treatments. Nutrient supply from natural sources, defined as crop content of N, P, and K at maturity without fertilizer application, amounted to 104, 16 and 103 kg ha−1, respectively, which are very high values. Total uptake of calcium and magnesium is related to that of potassium, as the combined content of these three elements is linearly related to total aboveground biomass production. Minimum removal of nitrogen and phosphorus per ton grain dry matter amounts to 29 and 4kg, respectively, and 9 kg potassium per ton total aboveground dry matter. A possible double function of phosphorus as element of structural biomass and for maintenance of electro-neutrality is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00750640
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  • 79
    Digitale Medien
    Digitale Medien
    Fertilizers and eutrophication in southwestern Australia: Setting the scene (1993)
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 95-103 
    Details
    ISSN: 1573-0867
    Schlagwort(e): eutrophication ; phosphorus ; fertilizer ; Peel-Harvey estuary ; algal blooms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract An excess of plant nutrients has caused serious eutrophication in aquatic ecosystems of southwestern Australia manifested by excessive growth and accumulation of green and bluegreen algae. Phosphorus is generally the limiting nutrient for algal growth and phosphatic fertilizers applied to nutrient-deficient, leaching, sandy soils are the main source of P, supplemented by rural industry point sources. Nitrogen is the limiting nutrient in marine embayments with little drainage from the land. Measures to reduce the load of P delivered to drainage include basing fertilizer application rates on soil testing for P and the use of less soluble P fertilizers. Catchment management plans are being implemented with community involvement to reduce P loads and maintain agricultural production. This introductory paper reviews the history of eutrophication in southwestern Australia and of studies into its causes, principally in the large Peel-Harvey estuary. It briefly summarises other papers in this special issue concerned with different aspects of the problem: how to fertilize the land without causing eutrophication.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00747579
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  • 80
    Digitale Medien
    Digitale Medien
    Phosphorus retention and release from sandy soils of the Peel-Harvey catchment (1993)
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 115-122 
    Details
    ISSN: 1573-0867
    Schlagwort(e): phosphorus ; retention ; release ; sandy soils
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract In order to manage phosphorus (P) losses from soils to waterbodies, knowledge of the mechanisms through which P is retained or released from the soil is essential. Sandy soils of the Peel-Harvey catchment (Western Australia) were subjected to a range of environmental and management factors in the laboratory and field in order to gain an understanding of the mechanisms that affect the magnitude of P losses. Sandy soils accumulated P, despite having little sorption capacity, and this accumulation could be monitored by measuring an acid-extractable fraction. The potential, short-term P loss could be estimated by determination of water-soluble soil solution P prior to winter rains. An annual cycle of the change in arbitrarily defined soil-P pools is discussed in relation to environmental and management factors. Laboratory experiments indicated that P rundown and potential annual P loss in the absence of P fertilizers could be estimated using bicarbonate extractable P. Phosphorus losses were decreased by the application of fertilizers with a low content of water-soluble P. The low ability of sandy soils of the Peel-Harvey coastal catchment to retain P, when compared to other Western Australian soils, is because of low contents of clay minerals and iron and aluminium hydrous oxides.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00747581
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  • 81
    Digitale Medien
    Digitale Medien
    The effect of level of nitrogen nutrition upon mineral content and removal in grasses and wheat (1990)
    Springer
    Nutrient cycling in agroecosystems 26 (1990), S. 229-235 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Grass ; wheat ; nitrogen nutrition ; dilution curve ; mineral content ; mineral removal ; phosphorus ; potassium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The important effect of nitrogen in changing the patterns of mineral content and mineral removal is analysed for grass swards and wheat. Different models are proposed; accumulated dry matter developed throughout a growing period is shown to be an excellent reference for assessing the evolution of the plant mineral content and the mineral removal the growing crop. Applications in diagnosing mineral nutrition status and optimising fertilizer use are proposed and discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01048760
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  • 82
    Digitale Medien
    Digitale Medien
    The interpretation of Olsen extractable P values in relation to recommendations for the fertilizer requirements of crops (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 223-227 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Soil testing ; phosphorus ; relative yield
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A greenhouse experiment, with Okra (Abelmoschus esculentus L.) as the test crop, was conducted on twenty-one soils ranging in Olsen's extractable phosphorus from 1.8 to 15.5µg Pg−1 soil. The experiment was conducted at Punjab Agricultural University, Ludhiana, India. The soils were nonsaline with pH ranging from 7.7 to 8.6. A critical level of 2.55µg Pg−1 soil was predicted by Cate and Nelson's (1971) statistical procedure. Because of a wide range in relative yields, this value did not accurately predict response to applied P. An approach to compute minimum response to applied fertilizer, which is likely to be obtained at a particular Olsen P level, has been presented. It involves calculation of lower 60 percent confidence limits for relative yield and fitting loge-linear regression to the transformed data. The regression was tested on a published data set and was found to hold well.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01048784
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  • 83
    Digitale Medien
    Digitale Medien
    Two post thinning fertilizer trials inPinus radiata in New South Wales, Australia (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 259-267 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Nitrogen ; phosphorus ; timber increment ; fertilization ; Pinus radiata
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Two trials inPinus radiata growing on different sites in N.S.W. allowed consideration of fertilizer applications after 2nd or 3rd thinning. The trials included factorial applications of N and P at a single thinning intensity plus a further treatment which allowed assessment of different thinning intensities. The most significant growth responses were obtained by application of N and P in combination. The largest response (additional productivity compared with the unfertilized control) occurred 4 years after application and after 7 years there was no additional absolute response for either of the two sites. The largest fertilizer response was 70 m3 ha−1 over 7 years on one site and 36 m3 ha−1 on the other, indicating differences in absolute responses between sites. It was concluded that in planning treatments the most responsive sites near the end of the rotation should be selected to maximise economic returns. Foliage analyses indicated differences between sites at the commencement of the study. It was concluded that either a single year of foliage analyses at study commencement is of value, or sampling every year of the study should be used to analyse responses, but a single year of analysis during or at the end of the study would not be of value.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01050363
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  • 84
    Digitale Medien
    Digitale Medien
    Effect of phosphate on the sorption, desorption and plant-availability of selenium in soil (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 189-197 
    Details
    ISSN: 1573-0867
    Schlagwort(e): interaction ; isotopic exchange ; phosphorus ; plant-availability ; selenium ; soil
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Phosphate, applied at 5µg P cm−3, decreased selenite sorption by from 30–70% in three soils studied. Both maximum sorption (Xm) and the binding-energy of sorption as indicated by the binding-energy related constant (k) or the molar free energy (ΔG) of the sorption reaction derived from the Langmuir equation were considerably decreased. On the other hand, phosphate sorption was decreased by increasing concentration of selenite from 0.2µg Se cm−3 to 1.0µg Se cm−3 in the initial solution. The competitive sorption of phosphate with selenite was likely the main mechanism involved in the P-Se interactions. The competitively sorbed selenite exhibited much larger desorption in 0.01M CaCl2 solution, more readily extractable to 0.5M NaHCO3 and significantly higher isotopic exchangeability compared to that sorbed without the competing anion. Results from pot trial using ryegrass indicated that phosphate application increased more efficiently the plant-availability of applied fertilizer Se than that of indegeneous Se in soil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00750246
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  • 85
    Digitale Medien
    Digitale Medien
    Metabolic pathways inParacoccus denitrificans and closely related bacteria in relation to the phylogeny of prokaryotes (1992)
    Springer
    Antonie van Leeuwenhoek 61 (1992), S. 1-33 
    Details
    ISSN: 1572-9699
    Schlagwort(e): Paracoccus denitrificans ; denitrification ; methylotrophy ; cytochromec ; cytochrome oxidase ; phylogeny ; evolution ; lateral gene transfer ; nitrogen fixation ; Thiosphaera pantotropha
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Denitrification and methylotrophy inParacoccus denitrificans are discussed. The properties of the enzymes of denitrification: the nitrate-nitrite antiporter, nitrate reductase, nitrite reductase, nitric oxide reductase and nitrous oxide reductase are described. The genes for none of these proteins have yet been cloned and sequenced fromP. denitrificans. A number of sequences are available for enzymes fromEscherichia coli, Pseudomonas stutzeri andPseudomonas aeruginosa. It is concluded that pathway specificc-type cytochromes are involved in denitrification. At least 40 genes are involved in denitrification. In methanol oxidation at least 20 genes are involved. In this case too pathway specificc-type cytochromes are involved. The sequence homology between the quinoproteins methanol dehydrogenase, alcoholdehydrogenase and glucose dehydrogenase is discussed. This superfamily of proteins is believed to be derived from a common ancestor. ThemoxFJGI operon determines the structural components of methanol dehydrogenase and the associatedc-type cytochrome. Upstream of this operon 3 regulatory proteins were found. The mox Y protein shows the general features of a sensor protein and the moxX protein those of a regulatory protein. Thus a two component regulatory system is involved in both denitrification and methylotrophy. The phylogeny of prokaryotes based on 16S rRNA sequence is discussed. It is remarkable that the 16S rRNA ofThiosphaera pantotropha is identical to that ofP. denitrificans. Still these bacteria show a number of differences.T. pantotropha is able to denitrify under aerobic circumstances and it shows heterotrophic nitrification. Nitrification and heterotrophic nitrification are found in species belonging to the β-and γ-subdivisions of purple non-sulfur bacteria. Thus the occurrence of heterotrophic nitrification inT. pantotropha which belongs to the α-subdivision of purple non-sulfur bacteria is a remarkable property. FurthermoreT. pantotropha contains two nitrate reductases of which the periplasmic one is supposed to be involved in aerobic denitrification. The nitrite reductase is of the Cu-type and not of the cytochromecd 1 type as inP. denitrificans. Also the cytochromeb of theQbc complex ofT. pantotropha is highly similar to its counterpart inP. denitrificans. It is hypothesized that the differences between these two organisms which both contain large megaplasmids is due to a combination of loss of genetic information and plasmid-coded properties. The distribution of a number of complex metabolic systems in eubacteria and in a number of species belonging to the α-group of purple non sulphur bacteria is reviewed. Two possibilities to explain this haphazard distribution are considered: 1. Lateral gene transfer between distantly related micro organisms occurs frequently. 2. The eubacterial ancestors must have possessed already these properties. The distribution of these properties is due to sporadic loss during evolutionary divergence. With respect to the occurrence and frequency of lateral gene transfer two opposing views exist. According to molecular biologists lateral gene transfer occurs frequently and is very easy. Bacteria are supposed to form one large gene pool. On the other hand population geneticists have provided evidence that strong systems operate that establish reproductive isolation between diverged species and even between closely related cell lines. Data on amino acid sequences of nitrogenase proteins, cytochromesc, cytochrome oxidases, β-subunits of ATP synthase and tryptophan biosynthetic enzymes of various micro organisms were reviewed. In all these cases phylogenetic trees could be constructed based on the amino acid sequence data. In all cases this phylogenetic tree was similar to the one based on 16S rRNA homology. Only in one case evidence for the occurrence of lateral gene transfer was obtained. Therefore it is concluded that lateral gene transfer played a minor role in the distribution of complex metabolic systems among prokaryotes. It must be stressed that this does not exclude the possibility that lateral gene transfer occurred frequently in the initial stage of bacterial evolution. It is hypothesized that the appearance of nitrogen fixation, denitrification and cytochrome oxidase formation were early events in the evolution of micro organisms. Both systems are supposed to have evolved only once. Subsequently the capacity to fix nitrogen or to denitrifymust have been lost many times, just as photosynthetic capacity is supposed to have been lost many times. During evolution many systems have been lost leading to a haphazard distribution of metabolic characters among bacteria. As an example it is suggested that organisms with a respiratory chain similar to that ofEscherichia coli arose by loss of the capacity to form the Qbc complex andc-type cytochromes. The remaining systems could be controlled much better however than in the ancestral organisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00572119
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  • 86
    Digitale Medien
    Digitale Medien
    Aboveground nitrogen and phosphorus use by five plantation-grown trees with different leaf longevities (1991)
    Springer
    Biodegradation 14 (1991), S. 167-191 
    Details
    ISSN: 1572-9729
    Schlagwort(e): leaf longevity ; nitrogen ; nutrient use efficiency ; phosphorus ; requirement ; retranslocation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Aboveground nitrogen (N) and phosphorus (P) requirement, retranslocation and use efficiency were determined for 28-year-old red oak (Quercus rubra L.), European larch (Larix decidua Miller), white pine (Pinus strobes L.), red pine (Pinus resinosa Ait.) and Norway spruce (Picea abies (L) Karst.) plantations on a similar soil in southwestern Wisconsin. Annual aboveground N and P requirements (kg/ha/yr) totaled 126 and 13 for red oak, 86 and 9 for European larch, 80 and 9 for white pine, 38 and 6 for red pine, and 81 and 13 for Norway spruce, respectively. Nitrogen and P retranslocation from current foliage ranged from 81 and 72%, respectively, for European larch, whereas red pine retranslocated the smallest amount of N (13%) and Norway spruce retranslocated the smallest amount of P (18%). In three evergreen species, uptake accounted for 72 to 74% of annual N requirement whereas for two deciduous species retranslocation accounted for 76 to 77% of the annual N requirement. Nitrogen and P use (ANPP/uptake) was more efficient in deciduous species than evergreen species. The results from this common garden experiment demonstrate that differences in N and P cycling among species may result from intrinsic characteristics (e.g. leaf longevity) rather than environmental conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00000806
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  • 87
    Digitale Medien
    Digitale Medien
    The evolution of pathways for aromatic hydrocarbon oxidation inPseudomonas (1994)
    Springer
    Biodegradation 5 (1994), S. 195-217 
    Details
    ISSN: 1572-9729
    Schlagwort(e): Aromatic catabolism ; by bacteria (Pseudomonas) ; evolution ; of catabolic pathways ; hydrocarbons ; catabolism of aromatic ; Pseudomonas ; evolution of catabolism in ; oxygenases ; evolution of
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The organisation and nucleotide sequences coding for the catabolism of benzene, toluene (and xylenes), naphthalene and biphenylvia catechol and the extradiol (meta) cleavage pathway inPseudomonas are reviewed and the various factors which may have played a part in their evolution are considered. The data suggests that the complete pathways have evolved in a modular way probably from at least three elements. The commonmeta pathway operons, downstream from the ferredoxin-like protein adjacent to the gene for catechol 2,3-dioxygenase, are highly homologous and clearly share a common ancestry. This common module may have become fused to a gene or genes the product(s) of which could convert a stable chemical (benzoate, salicylate, toluene, benzene, phenol) to catechol, thus forming the lower pathway operons found in modern strains. The upper pathway operons might then have been acquired as a third module at a later stage thus increasing the catabolic versatility of the host strains.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00696460
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    Digitale Medien
    Digitale Medien
    Defective ommatidial cell assembly leads to defective morphogenesis: a phenotypic analysis of the E(spl) D mutation of Drosophila melanogaster (1990)
    Springer
    Development genes and evolution 198 (1990), S. 286-294 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Compound eye morphogenesis ; Enhancer of split ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The spl mutation of the N gene causes, among other phenotypic traits, the lack of a few ommatidia, roughness and a general reduction in the size of the compound eye; these defects are drastically enhanced by the dominant mutation E(spl) D. We have studied cellular and developmental aspects of the phenotypic interaction between spl and E(spl) D. We found that the initial clustering of photoreceptor cells is affected in eye imaginal discs of spl larvae causing the defects visible in the adult eye. The degree of disorganization of the spl/Y; E(spl) D/ + eye disc is much higher, only a few photoreceptor cells are able to group with representatives of the other cell types and differentiate normally. BrdU incorporation shows that the proliferation pattern of the spl/Y; E(spl) D/ + disc cells during the third instar is normal. Abundant cell death occurs posteriorly in the mutant discs, which accounts for their small size. Finally, we found that in the eye imaginal disc the transcription of m8, the E(spl) gene, responsible for the enhancement of the spl phenotype caused by the E(spl) D mutation, is restricted to the morphogenetic furrow, where the ommatidial cells start grouping with each other to take on their future developmental fates; the m8 transcription rate is highly increased in E(spl) D eye discs. All these observations indicate that the assembly of the ommatidial cells is affected in the spl/Y; E(spl) D/ + disc and that the other abnormalities are morphogenetic consequences of the defective cell grouping.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00377395
    Standort Signatur Erwartet Verfügbarkeit
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  • 89
    Digitale Medien
    Digitale Medien
    Hormonally regulated expression of arginine kinase in Drosophila melanogaster (1990)
    Springer
    Development genes and evolution 198 (1990), S. 474-478 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Arginine kinase ; Imaginal discs ; 20-hydroxyecdysone ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Arginine kinase (AK) is present throughout the life cycle of Drosophila melanogaster, but there is a sharp, transient peak of AK activity during the prepupal period and a second period of elevated activity at the time of eclosion of the adult. Imaginal discs show the greatest increase in AK activity at the prepupal stage of those tissues assayed. The prepupal peak is not seen when the temperature-sensitive ecdysoneless mutant ecd-1 is shifted to 29° C at mid-third instar larval stage. The peak in activity reappears when ecd-1 is either shifted back to 20° C after 60 h at 29° C or is fed 20-hydroxyecdysone. At the restrictive temperature, imaginal discs from ecd-1 larvae progressively lose AK activity, whereas discs from 20-hydroxyecdysone-fed larvae have a marked increase in AK activity at stage P3 of the prepupal period. These data suggest that the prepupal peak is regulated by the hormone 20-hydroxyecdysone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00399058
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
    Digitale Medien
    Digitale Medien
    The diversity of cell morphology in cloned cell lines derived from Drosophila imaginal discs (1990)
    Springer
    Development genes and evolution 198 (1990), S. 479-482 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Imaginal disc ; Cell culture, wing ; In vitro
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have devised a protocol for the cloning of our cell lines, and have demonstrated that a cloned line may contain cells of widely differing morphology — epithelial, fibroblast-like, and lamellocyte-like. These different morphologies must therefore represent diversity in the microenvironment of the culture rather than diversity in the cellular origin of the line.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00399059
    Standort Signatur Erwartet Verfügbarkeit
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  • 91
    Digitale Medien
    Digitale Medien
    Sensitive periods for abnormal patterning on a leg segment inDrosophila melanogaster (1990)
    Springer
    Development genes and evolution 199 (1990), S. 31-47 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Bristle ; Pattern formation ; Drosophila ; Gamma rays ; Mitomycin C ; Heat shock
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The development of a leg segment of the fruitflyDrosophila melanogaster was analyzed in order to determine whether the orderliness of the segment's bristle pattern originates via waves of cellular interactions, such as those that organize the retina. Fly development was perturbed at specific times by either teratogenic agents (gamma rays, heat shock, or the drug mitomycin C) or temperature-sensitive mutations (l(1)63, l(1) Notchts1, orl(1) shibire ts1 ), and the resulting abnormalities (e.g., missing or extra structures) were mapped within the pattern area. If bristles develop in a linear sequence across the pattern, then they should show sensitivity to perturbations in the same order, and wavefronts of cuticular defects should result. Contrary to this prediction, the maps reveal no evidence for any directional waves of sensitivity. Nevertheless, other clues were uncovered as to the nature and timing of patterning events. Chemosensory bristles show earlier sensitivities than mechanosensory bristles, and longer bristles precede shorter ones. The types and sequence of cuticular abnormalities imply the following stages of bristle pattern development: (1) scattered inception of bristle mother cells, each surrounded by an inhibitory field, (2) alignment of the mother cells into rows, (3) differential mitoses, (4) assignment of cuticular fates to the mitotic progeny, (5) polytenization of the bristle cells, (6) fine-tuning adjustments in bristle spacing, and (7) signalling from bristle cells to adjacent epidermal cells, inducing them to form “bracts”.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01681531
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Digitale Medien
    Digitale Medien
    Arrangement of bristles as a function of bristle number on a leg segment inDrosophila melanogaster (1990)
    Springer
    Development genes and evolution 199 (1990), S. 48-62 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Bristle ; Sensilla ; Pattern formation ; Drosophila ; achaete-scute complex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The arrangement of bristles on a leg segment of the fruitflyDrosophila melanogaster was studied in various mutants that have abnormal numbers of bristles on this segment. Eighteen mutations at six different genetic loci were analyzed, plus five double or triple mutant combinations. Recessive mutations at theachaete-scute locus were found to affect distinct groups of bristles:achaete mutations remove mechanosensory bristles, whereasscute mutations remove mainly chemosensory bristles. Mechanosensory bristles remain uniformly spaced along the longitudinal axis unless their number decreases below a certain threshold, suggesting that spacing is controlled by cell interactions that cannot function when bristle cells are too far apart. Above a certain threshold, bristle spacing and alignment both become irregular, perhaps due to excessive force from these same interactions. Chemosensory bristles occupy definite positions that are virtually unaffected by removal of individual bristles from the array. Extra chemosensory bristles develop only near the six normal sites. At two of the six sites the multiple bristles tend to exhibit uniform longitudinal spacing — a property confined to mechanosensory bristles in wild-type flies. To explain the various mutant phenotypes the following scheme is proposed, with different mutations directly or indirectly affecting each step: (1) spots and stripes are demarcated within the pattern area, (2) one bristle cell normally arises within each spot, multiple bristle cells within each stripe, (3) incipient bristle cells inhibit neighboring cells from becoming bristle cells, and (4) the bristle cells within each stripe become aligned to form rows and then repel one another to generate uniform spacing.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01681532
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
    Digitale Medien
    Digitale Medien
    Developmental effects of monensin on Drosophila melanogaster (1993)
    Springer
    Development genes and evolution 203 (1993), S. 83-91 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Monensin ; Extracellular matrix ; Membrane proteins ; Morphogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Extracellular matrix and membrane proteins and their correct secretion probably are key elements in morphogenesis and differentiation in Drosophila. In this study, we have analysed the effects of monensin, a Na+-H+-ionophore which blocks normal secretion, applied during cellular blastoderm formation on further development. Normal cell morphology and intercellular contacts are lost and the extracellular matrix becomes disorganized. Gastrulation is blocked and abnormal foldings can be observed. Cuticle phenotypes showed different degrees of ventral, dorsal, head and posterior defects. The results are discussed in the context of what is known about membrane and extracellular matrix proteins in Drosophila.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00539893
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  • 94
    Digitale Medien
    Digitale Medien
    BrdU incorporation reveals DNA replication in non dividing glial cells in the larval abdominal CNS ofDrosophila (1994)
    Springer
    Development genes and evolution 204 (1994), S. 54-61 
    Details
    ISSN: 1432-041X
    Schlagwort(e): CNS ; Glia ; Drosophila ; BrdU
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Glial cells are of significant importance for central nervous system development and function. In insects, knowledge of the types and development of CNS glia is rather low. This is especially true for postembryonic glial development. Using bromodeoxyuridine incorporation and enhancer trap lines we identified a reproducible spatial and temporal pattern of DNA replicating cells in the abdominal larval CNS (A3-7 neuromeres) ofDrosophila melanogaster. These cells correspond to embryonically established glial cells in that region. Except for a specific subfraction, these cells apparently do not divide during larval life. Similar patterns were found in two otherDrosophila species,D. virilis andD. hydei.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00744873
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  • 95
    Digitale Medien
    Digitale Medien
    Progressive determination of cell fates along the dorsoventral axis in the sea urchin Heliocidaris erythrogramma (1994)
    Springer
    Development genes and evolution 204 (1994), S. 62-69 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Cell determination ; direct development dorsoventral axis ; echinoids ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In the direct-developing sea urchinHeliocidaris erythrogramma the first cleavage division bisects the dorsoventral axis of the developing embryo along a frontal plane. In the two-celled embryo one of the blastomeres, the ventral cell (V), gives rise to all pigmented mesenchyme, as well as to the vestibule of the echinus rudiment. Upon isolation, however, the dorsal blastomere (D) displays some regulation, and is able to form a small number of pigmented mesenchyme cells and even a vestibule. We have examined the spatial and temporal determination of cell fates along the dorsoventral axis during subsequent development. We demonstrate that the dorsoventral axis is resident within both cells of the two-celled embryo, but only the ventral pole of this axis has a rigidly fixed identity this early in development. The polarity of this axis remains the same in half-embryos developing from isolated ventral (V) blastomeres, but it can flip 180° in half-embryos developing from isolated dorsal (D) blastomeres. We find that cell fates are progressively determined along the dorsoventral axis up to the time of gastrulation. The ability of dorsal half-embryos to differentiate ventral cell fates diminishes as they are isolated at progressively later stages of development. These results suggest that the determination of cell fates along the dorsoventral axis inH. erythrogramma is regulated via inductive interactions organized by cells within the ventral half of the embryo.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00744874
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  • 96
    Digitale Medien
    Digitale Medien
    Drosophila glial development is regulated by genes involved in the control of neuronal cell fate (1994)
    Springer
    Development genes and evolution 204 (1994), S. 118-125 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; glia ; Proneural ; Neurogenic
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The Drosophila proneural genes specify neuronal determination among cells within the ectoderm. Here we address the question of whether proneural genes also affect the specification of glia, the most abundant cell type in the nervous system. We provide evidence that the proneural gene daughterless is essential for the formation of two major classes of PNS glia. In contrast, the proneural genes in the achaete-scute complex have no detectable effect on the specification and differentiation of these PNS glia and certain CNS glia. We also show that, as with neuronal development, glial determination is restricted by the neurogenic genes neuralized, Delta, and the genes of the Enhancer of split complex. Finally, we demonstrate that prospero, a gene involved in neuronal differentiation, also affects glial development. These results demonstrate extensive overlap in the genetic control of glial and neuronal development.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00361106
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  • 97
    Digitale Medien
    Digitale Medien
    Polymorphism in the giant cocoa termite,Neotermes papua (Desneux) (1991)
    Springer
    Insectes sociaux 38 (1991), S. 263-272 
    Details
    ISSN: 1420-9098
    Schlagwort(e): Isoptera ; Kalotermitidae ; Neotermes papua ; termites ; caste differentiation ; division of labour ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The direct development ofNeotermes papua (Isoptera: Kalotermitidae) comprises four larval and three nymphal instars before the alate. The first five instars can be easily characterized. The second stage nymphs come morphologically close to the pseudergates, characterized by reduced wing buds. These nymphs can moult stationarily, i.e. with little morphological change, or to presoldiers, or proceed to the alate via the third nymphal stage. Pseudergates originate through a late and reversible deviation from the straight development to the alate. Presoldiers may derive from several stages, up to the last nymphal one; their production is subject to an inhibition by extant soldiers. This developmental schema is congruent with those described in other Kalotermitidae and the Termopsidae. By pinpointing the existence of a large pool of pluripotent individuals, in which the penultimate nymphal stage mingles with pseudergates, the present study also reveals a great similarity betweenNeotermes andProrhinotermes, and suggests that this developmental schema might be generally applicable to termites devoid of a permanent worker caste.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01314912
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  • 98
    Digitale Medien
    Digitale Medien
    Molecular cloning and sequencing of 18S rDNA gene fragments from six different ant species (1993)
    Springer
    Insectes sociaux 40 (1993), S. 325-335 
    Details
    ISSN: 1420-9098
    Schlagwort(e): Formicidae ; social parasitism ; PCR ; 18 S ribosomal RNA ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The evolutionary relationship between socially parasitic ants and their hosts is still an unsolved problem. We have compared a 1.2 kb sequence of the 18 S ribosomal RNA genes of the parasitic antsDoronomyrmex kutteri, Harpagoxenus sublaevis andChalepoxenus muellerianus to the sequence of the host speciesLeptothorax acervorum andL. recedens (all subfamily Myrmicinae, tribe Leptothoracini) and to an out-group antCamponotus ligniperda (Formicinae). We found that parasitic species and the host species and alsoCamponotus ligniperda differ at less than 1% of the base positions of the 1.2 kb segment of the 18S rRNA gene. The sequences showed 80.3% identity to the 18 S ribosomal RNA genes of the beetleTenebrio molitor and only 66.5% to that of the dipteranDrosophila melanogaster.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01242369
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  • 99
    Digitale Medien
    Digitale Medien
    Development of non-reproductive castes in the neotropical termite generaCornitermes, Embiratermes andRhynchotermes (Isoptera, Nasutitermitinae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 313-324 
    Details
    ISSN: 1420-9098
    Schlagwort(e): Isoptera ; Termitidae ; Nasutitermitinae ; caste differentiation ; phylogeny ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The developmental pattern of the neuter castes was studied in the mandibulate nasute generaCornitermes, Embiratermes andRhynchotermes. InCornitermes walkeri, all the workers and soldiers are male. There are two larval and a single worker instar. Workers can molt into presoldiers. InEmbiratermes chagresi andRhynchotermes perarmatus, both sexes are present among the neuters. A slight sexual dimorphism (males 〉 females) is discernible among both larval instars and among workers ofE. chagresi; female workers can molt into presoldiers. InR. perarmatus, the sexual dimorphism is conspicuous from the first larval instar on. Male larvae go through two instars, then give rise to workers, which do not molt. InR. perarmatus, there is no worker stage in females, but a third larval instar, preceding the presoldier. Hypotheses are proposed as to the evolution of these caste patterns, attempting to conciliate present knowledge of Nasutitermitinae phylogeny and known evolutionary trends affecting termite caste patterns, according to the species' ecology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01323951
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  • 100
    Digitale Medien
    Digitale Medien
    Social organization in some primitive Australian ants. I.Nothomyrmecia macrops Clark (1992)
    Springer
    Insectes sociaux 39 (1992), S. 425-438 
    Details
    ISSN: 1420-9098
    Schlagwort(e): Formicidae ; Nothomyrmecia ; evolution ; sociogram ; ethogram ; recognition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Results of laboratory-based ethological studies on twoNothomyrmecia macrops colonies with individually marked workers are reported. Interactive behavioural acts constituted less than 1% of all those recorded, revealing a strong tendency by the ants not to engage in social contact. Very few workers performed queen-directed acts. They stayed near the queen, though seldom in direct contact. Division of labour was otherwise barely apparent, except that some individuals showed a propensity to guard the nest entrance. No exchange of food was observed between workers, workers and queen, or adults and larvae (apart from worker placement of prey items with larvae). A queen fed from aDrosophila carcass retrieved from the nest floor, without assistance from workers. Systematic scanned observations confirmed levels of inactivity higher than previously observed in ants (comprising almost 2/3 of recorded behavioural acts). The time budget for activities directed toward the immature stages was the same in both colonies, and fluctuated during the circadian period. Non-nestmate larvae added to worker groups were more frequently licked than nestmate larvae, but this might not involve the particular recognition of nestmateversus non-nestmate brood. These observations support the hypothesis thatNothomyrmecia is primitively eusocial, and of special significance in myrmecology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01240625
    Standort Signatur Erwartet Verfügbarkeit
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