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  • 1
    Publication Date: 2022-05-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Mayers, K. M. J., Poulton, A. J., Bidle, K., Thamatrakoln, K., Schieler, B., Giering, S. L. C., Wells, S. R., Tarran, G. A., Mayor, D., Johnson, M., Riebesell, U., Larsen, A., Vardi, A., & Harvey, E. L. The possession of coccoliths fails to deter microzooplankton grazers. Frontiers in Marine Science, 7, (2020): 562020, doi:10.3389/fmars.2020.569896.
    Description: Phytoplankton play a central role in the regulation of global carbon and nutrient cycles, forming the basis of the marine food webs. A group of biogeochemically important phytoplankton, the coccolithophores, produce calcium carbonate scales that have been hypothesized to deter or reduce grazing by microzooplankton. Here, a meta-analysis of mesocosm-based experiments demonstrates that calcification of the cosmopolitan coccolithophore, Emiliania huxleyi, fails to deter microzooplankton grazing. The median grazing to growth ratio for E. huxleyi (0.56 ± 0.40) was not significantly different among non-calcified nano- or picoeukaryotes (0.71 ± 0.31 and 0.55 ± 0.34, respectively). Additionally, the environmental concentration of E. huxleyi did not drive preferential grazing of non-calcified groups. These results strongly suggest that the possession of coccoliths does not provide E. huxleyi effective protection from microzooplankton grazing. Such indiscriminate consumption has implications for the dissolution and fate of CaCO3 in the ocean, and the evolution of coccoliths.
    Description: Mesocosm experiments in 2015 were supported by the Kiel Excellence Cluster “The Future Ocean” (CP1540) and the Leibniz Award to UR, in 2017 the MESOHUX experiment was supported by NSF (OCE-1559179) to KT and KB, NSF (OCE-1537951 and OCE-1459200) to KB, NSF (OCE-1459190, 1657808, and DBI-1624593) to EH, and in 2018 by AQUACOSM (EU H2020-INFRAIA-project No 731065). KM was supported by a NERC Doctoral Training Partnership (DTP) studentship as part of the Southampton Partnership for Innovative Training of Future Investigators Researching the Environment (SPITFIRE, grant number NE/L002531/1) and Research Council of Norway project (#280414) MIXsTRUCT.
    Keywords: coccolithophore ; phytoplankton ; microzooplankton ; biomineralisation ; predation ; evolution
    Repository Name: Woods Hole Open Access Server
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  • 2
    Publication Date: 2022-05-25
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Beam, J. P., Becraft, E. D., Brown, J. M., Schulz, F., Jarett, J. K., Bezuidt, O., Poulton, N. J., Clark, K., Dunfield, P. F., Ravin, N. V., Spear, J. R., Hedlund, B. P., Kormas, K. A., Sievert, S. M., Elshahed, M. S., Barton, H. A., Stott, M. B., Eisen, J. A., Moser, D. P., Onstott, T. C., Woyke, T., & Stepanauskas, R. Ancestral absence of electron transport chains in Patescibacteria and DPANN. Frontiers in Microbiology, 11, (2020): 1848, doi:10.3389/fmicb.2020.01848.
    Description: Recent discoveries suggest that the candidate superphyla Patescibacteria and DPANN constitute a large fraction of the phylogenetic diversity of Bacteria and Archaea. Their small genomes and limited coding potential have been hypothesized to be ancestral adaptations to obligate symbiotic lifestyles. To test this hypothesis, we performed cell–cell association, genomic, and phylogenetic analyses on 4,829 individual cells of Bacteria and Archaea from 46 globally distributed surface and subsurface field samples. This confirmed the ubiquity and abundance of Patescibacteria and DPANN in subsurface environments, the small size of their genomes and cells, and the divergence of their gene content from other Bacteria and Archaea. Our analyses suggest that most Patescibacteria and DPANN in the studied subsurface environments do not form specific physical associations with other microorganisms. These data also suggest that their unusual genomic features and prevalent auxotrophies may be a result of ancestral, minimal cellular energy transduction mechanisms that lack respiration, thus relying solely on fermentation for energy conservation.
    Description: This work was funded by the USA National Science Foundation grants 1441717, 1826734, and 1335810 (to RS); and 1460861 (REU site at Bigelow Laboratory for Ocean Sciences). RS was also supported by the Simons Foundation grant 510023. TW, FS, and JJ were funded by the U.S. Department of Energy Joint Genome Institute, a DOE Office of Science User Facility supported under Contract No. DE-AC02-05CH11231. NR group was funded by the Russian Science Foundation (grant 19-14-00245). SS was funded by USA National Science Foundation grants OCE-0452333 and OCE-1136727. BH was funded by NASA Exobiology grant 80NSSC17K0548.
    Keywords: Bacteria ; Archaea ; evolution ; genomics fermentation ; respiration ; oxidoreductases
    Repository Name: Woods Hole Open Access Server
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  • 3
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    Journal of ornithology 141 (2000), S. 263-274 
    ISSN: 1439-0361
    Keywords: Systematics ; evolution ; anagenesis ; genealogy ; reference system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Verglichen mit anderen Tiergruppen, scheint die artliche Bestandsaufnahme der rezenten Vögel nahezu abgeschlossen zu sein. Doch ist das System der Vögel weiterhin umstritten und mit vielen Neuerungen konfrontiert. Die Gründe dafür liegen hauptsächlich in neuen, vor allem molekularbiologischen Methoden und in den unerwartet reichen Fossilfunden der jüngsten Zeit. Als Beispiele werden Altgaumenvögel, Kranichvögel, Ibisse, Flamingos, Mausvögel, Hopfe und Sperlingsvögel kurz behandelt. Die hier erzielten Fortschritte lassen die Befürchtung Stresemanns, die Großsystematik der Vögel sei mit den vorhandenen Methoden phylogenetisch nicht interpretierbar, zunächst als unbergründet erscheinen. Doch erwachsen einer solchen Interpretation andere Hindernisse, deren Bedeutung bisher zu wenig beachtet wurde, nämlich Parallelentwicklungen, die viel verbreiteter sind als gemeinhin angenommen. Ihre Häufigkeit lässt sich sogar mit evolutionsbiologischen Argumenten begründen. Es ist deshalb nicht zu erwarten, dass die Diskussionen um das „richtige“ System bald verstummen. Um dennoch die Eindeutigkeit der Information in nicht-systematischen Veröffentlichungen zu wahren, wird empfohlen ein etabliertes Referenzsystem auf Zeit zu wählen.
    Notes: Summary Unlike in most animal classes the inventory of extant species of the class Aves seems to be almost complete. Nevertheless avian systematics is challenged by many novelties and seems far from being settled. This is caused mainly by the application of novel methods of molecular analysis to phylogenetic problems and by the unexpectedly rich fossil record collected within the last 10–20 years. Examples from the Palaeognathae, Gruiformes, Threskiornithidae, Phoenicopteridae, Coliiformes, Upupiformes and Passeriformes are briefly treated. The progress in the field seems to disprove Stresemann's pessimistic view that the phylogeny of higher categories (orders) cannot be reconstructed by the available methods. However, phylogenetic interpretations are impeded by obstacles not considered by Stresemann and highly underestimated in most cases, namely by multiple independent developments leading to identical features. Frequent parallel developments are to be expected for theoretical evolutionary reasons. The diagnosis of such homoplasies can be extremely difficult or even impossible. Therefore we cannot expect the discussion about the “best” system of birds to end in the near future. Considering this dynamic situation in systematics, it is recommended to maintain unambiguousness of information in not strictly systematic publications by refering to a well established system as a temporally limited reference.
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  • 4
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Tortricidae ; reproduction ; tebufenozide ; methoxyfenozide ; ecdysone agonist ; Argyrotaenia velutinana ; Choristoneura rosaceana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects on the fecundity and fertility of redbanded leafroller, Argyrotaenia velutinana (Walker), and obliquebanded leafroller,Choristoneura rosaceana (Harris), exposed as adults to surfaces treated with the ecdysone agonists tebufenozide (RH-5992) and methoxyfenozide (RH-2485) were examined. The first part of the study consisted of recently emerged moths being exposed to treated surfaces continuously throughout their lives (including mating and oviposition). Continuous exposure to tebufenozide- or methoxyfenozide-treated surfaces significantly reduced the mean number of eggs laid and the percent of eggs that hatched in both species. The second part of the study involved exposure of recently emerged virgin moths (by sex) to treated surfaces for 24 h, after which, the exposed moths were paired with a nontreated partner to mate and oviposit on nontreated surfaces. In this experiment, for A. velutinana, significant reductions in fecundity occurred only when the female was exposed to methoxyfenozide-treated surfaces. Significant reductions in A. velutinana egg fertility occurred with both male and female exposure in the methoxyfenozide treatments and only female exposure in the tebufenozide treatments. For C. rosaceana, significant reductions in fecundity occurred with both male and female exposure in the tebufenozide and methoxyfenozide treatments. Significant reductions in C. rosaceana egg fertility occurred with both male and female exposure in the tebufenozide treatments and only with female exposure in the methoxyfenozide treatments.
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  • 5
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    Entomologia experimentalis et applicata 95 (2000), S. 217-227 
    ISSN: 1570-7458
    Keywords: antifeedant ; drimane ; mechanism of action ; sensory response ; toxicity ; habituation ; behavioural observation ; structure-activity relationship ; Pieris brassicae ; Lepidoptera ; Pieridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We tested 11 analogous synthetic drimane antifeedant compounds for their feeding inhibiting effects on larvae of the large white butterfly Pieris brassicae L. (Lepidoptera: Pieridae) in no-choice tests on the host plant Brassica oleracea L. Furthermore, we observed larval feeding behaviour in no-choice tests to analyze temporal effects of five drimanes. The results show that the five analogous antifeedants differentially influence feeding behaviour and locomotion activity. Warburganal and polygodial are most likely sensory mediated antifeedants. Habituation to these compounds occurs soon after the onset of the tests (i.e., within 0.5–1.5 h). Compound 5 and confertifolin are probably not direct, sensory mediated antifeedants. After 0.5–1.5 h of exposure, these compounds inhibit not only feeding, but also locomotion behaviour, indicating postingestive, toxic effects. Isodrimenin inhibits feeding from the onset of the test and is probably a sensory mediated antifeedant. No habituation occurs to this compound, indicating that isodrimenin is either a very strong antifeedant or that it additionally has postingestive, toxic effects. Topical application of the drimanes on the larval cuticle revealed feeding inhibiting effects, but these could not be related to the occurrence of postingestive feeding inhibiting effects, indicating that this method is inappropriate to show possible postingestive effects of drimanes in P. brassicae. In conclusion, the behavioural observations performed in this research indicate that analogous drimanes inhibit feeding by P. brassicae larvae through multiple mechanisms of action. The results show that, when developing a structure activity relationship (SAR) for a series of antifeedants, it is important to distinguish the mode of action which underlies inhibition of feeding.
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  • 6
    ISSN: 1570-7458
    Keywords: Cnaphalocrocis medinalis ; rice leaffolder ; Lepidoptera ; Pyralidae ; sex pheromone ; geographical variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sex pheromone components of the Japanese rice leaffolder moth, Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae) were identified from ovipositor extracts of virgin females as (Z)-11-octadecenal, (Z)-13-octadecenal, (Z)-11-octadecen-1-ol and (Z)-13-octadecen-1-ol at a ratio of 11:100:24:36 by GC-EAD, GC, GC-MS. The total amount was estimated to be ca.0.9 ng/female. Field bioassays in Kagoshima, Japan, showed that the two aldehydes are essential for male attraction and the alcohols may have a synergistic effect on the aldehydes. A rubber septum containing 0.9 mg of the four components at the natural ratio was shown to be an effective lure for monitoring this pest in Japan. The above four components are quite different from the sex pheromone components reported previously for the same species of either Philippine or Indian origin; components were shown to be (Z)-11-hexadecenyl acetate and (Z)-13-octadecenyl acetate at a ratio of 98:2 in the Philippine blend and 1:10 in the Indian blend. Furthermore, in the field tests in Japan, neither the Philippine blend nor the Indian blend showed any attractive activity, while the Japanese blend attracted significant numbers of male moths. These results suggest that there are remarkable geographical variations in the sex pheromone composition of this species or there are several distinct species using different sex pheromone blends.
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  • 7
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    Entomologia experimentalis et applicata 97 (2000), S. 137-147 
    ISSN: 1570-7458
    Keywords: Etiella zinckenella ; Etiella hobsoni ; Lepidoptera ; Pyralidae ; soybean ; development ; reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experiments conducted in West Java, Indonesia investigated the developmental biology and reproductive behavior of two sympatric soybean pod borers, Etiella zinckenella Treitschke and E. hobsoni Butler (Lepidoptera: Pyralidae). It was determined that: (1) significant interspecific differences occurred between the egg, larval, pupal and total egg-to-adult developmental periods of laboratory raised E. zinckenella and E. hobsoni; (2) the pre-pupal and total egg-to-adult development periods of female E. zinckenella were significantly shorter than for males; (3) the longevity of virgin female E. zinckenella was significantly longer than that of virgin males, or virgin male and female E. hobsoni; (4) interspecific differences occurred in the female: male sex-ratios of laboratory raised adults; (5) peak mating for both species occurred on the second night after eclosion; (6) interspecific differences occurred in the temporal distribution of calling and mating behaviors; (7) repeated mating was observed for both species at a very low frequency; (8) interspecific mating did not occur; (9) female E. zinckenella were significantly more fecund than E. hobsoni; (10) the duration in copulo of E. zinckenella was significantly longer than that of E. hobsoni; and (11) wingtraps baited with virgin females caught only conspecific males, and reduced numbers of males were captured in traps simultaneously baited with virgin females of both species. This study demonstrates distinct biological differences and reproductive isolation between the two Etiella spp.
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  • 8
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    Acta biotheoretica 48 (2000), S. 137-147 
    ISSN: 1572-8358
    Keywords: Sex ; sexual selection ; mate selection ; evolution ; ploidy ; assortative mating ; recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using computer simulations I studied the simultaneous effect of variable environments, mutation rates, ploidy, number of loci subject to evolution and random and assortative mating on various reproductive systems. The simulations showed that mutants for sex and recombination are evolutionarily stable, displacing alleles for monosexuality in diploid populations mating assortatively under variable selection pressure. Assortative mating reduced excessive allelic variance induced by recombination and sex, especially among diploids. Results suggest a novel adaptive value for sex and recombination. They show that the adaptive value of diploidy and that of the segregation of sexes is different to that of sex and recombination. The results suggest that the emergence of sex had to be preceded by the emergence of diploid monosexual organisms and provide an explanation for the emergence and maintenance of sex among diploids and for the scarcity of sex among haploid organisms.
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  • 9
    ISSN: 1570-7458
    Keywords: calling behaviour ; periodicity ; sex pheromone ; attraction inhibitor ; attraction synergist ; field tests ; Lepidoptera ; Gracillariidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Females of the leaf miner moth Phyllonorycter acerifoliella (Z.) [=Ph. sylvella (Hw.)] and Ph. heegerella (Z.) (Lepidoptera: Gracillariidae: Lithocolletinae) release their sex pheromone at the beginning of photophase. The periodicity of the `calling' behaviour of Ph. acerifoliella females was established. Three compounds from calling virgin Ph. heegerella females were collected by the Solid Phase Micro Extraction (SPME) technique and identified as (Z)-8-tetradecenyl acetate (Z8-14:OAc), tetradecyl acetate (14:OAc) and (Z)-8-tetradecenol (Z8-14:OH) in the ratio (88±3):(2±0.6):(10±5) by capillary gas chromatography and mass spectrometry. Field trapping experiments demonstrated that the first two compounds are important for the attraction of conspecific males. Z8-14:OAc was found to be attractive when tested separately, while 14:OAc acted as synergist. The attractivity of the three component blend was reduced by 10% admixture of either (E)-10-dodecenyl acetate (E10-12:OAc) or (Z)-10-tetradecenyl acetate (Z10-14:OAc). Field tests of Z10-, Z8- and E10-14:OAc, identified from Ph. acerifoliella females, demonstrated that the first two compounds were essential for the attraction of conspecific males; so both are sex pheromone components. The attractivity of the three component blend of Z10- Z8- and E10-14:OAc was reduced by 10% admixture of (E)-10-dodecenol (E10-12:OH). The following four semiochemical compounds, Z8-14:OAc, Z8-14:OH, E10-14:OAc and 14:OAc, identified from phyllonoryctid females, as well as two sex attraction antagonists for Ph. acerifoliella and Ph. heegerella males, E10-12:OAc and Z10-14:OAc, are new for the family Gracillariidae. The results of field trapping experiments revealed mechanisms ensuring the specificity of the chemocommunication systems in Ph. acerifoliella, Ph. heegerella and Ph. ulmifoliella (Hb.) moths.
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  • 10
    ISSN: 1570-7458
    Keywords: EPG ; stylectomy ; phloem amino acids ; nitrogen ; aphid-plant interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of nitrogen deficiency in hydroponically grown barley seedlings (Hordeum vulgare L.) on the development and reproduction of the aphid Rhopalosiphum padi (L.) (Hemiptera: Aphididae) were investigated. Plant growth was significantly reduced in seedlings grown without nitrogen. Aphid intrinsic rate of increase (r m) was also significantly lower on these plants compared with that on plants grown with 8 mol m−3 nitrogen. Phloem sap was collected from seedling stems by aphid stylectomy and amino acids quantified by HPLC. There was a significant reduction in the concentration of non-essential amino acids as a group, but not of essential amino acids. Electrical penetration graphs (EPG) indicated that aphids reached the phloem more quickly and fed for longer on plants grown with nitrogen. This is the first reported study in which this combination of techniques has been used to understand the interactions of an aphid and plant under different environmental conditions.
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  • 11
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    Entomologia experimentalis et applicata 97 (2000), S. 237-249 
    ISSN: 1570-7458
    Keywords: herbivores ; predators ; parasitoids ; mutualism ; induced defence ; behaviour ; ecology ; evolution ; sensory physiology ; plant fitness ; pathogens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Herbivorous and carnivorous arthropods use plant volatiles when foraging for food. In response to herbivory, plants emit a blend that may be quantitatively and qualitatively different from the blend emitted when intact. This induced volatile blend alters the interactions of the plant with its environment. We review recent developments regarding the induction mechanism as well as the ecological consequences in a multitrophic and evolutionary context. It has been well established that carnivores (predators and parasitoids) are attracted by the volatiles induced by their herbivorous victims. This concerns an active plant response. In the case of attraction of predators, this is likely to result in a fitness benefit to the plant, because through consumption a predator removes the herbivores from the plant. However, the benefit to the plant is less clear when parasitoids are attracted, because parasitisation does usually not result in an instantaneous or in a complete termination of consumption by the herbivore. Recently, empirical evidence has been obtained that shows that the plant's response can increase plant fitness, in terms of seed production, due to a reduced consumption rate of parasitized herbivores. However, apart from a benefit from attracting carnivores, the induced volatiles can have a serious cost because there is an increasing number of studies that show that herbivores can be attracted. However, this does not necessarily result in settlement of the herbivores on the emitting plant. The presence of cues from herbivores and/or carnivores that indicate that the plant is a competitor- and/or enemy-dense space, may lead to an avoidance response. Thus, the benefit of emission of induced volatiles is likely to depend on the prevailing faunal composition. Whether plants can adjust their response and influence the emission of the induced volatiles, taking the prevalent environmental conditions into account, is an interesting question that needs to be addressed. The induced volatiles may also affect interactions of the emitting plant with its neighbours, e.g., through altered competitive ability or by the neighbour exploiting the emitted information. Major questions to be addressed in this research field comprise mechanistic aspects, such as the identification of the minimally effective blend of volatiles that explains the attraction of carnivores to herbivore-infested plants, and evolutionary aspects such as the fitness consequences of induced volatiles. The elucidation of mechanistic aspects is important for addressing ecological and evolutionary questions. For instance, an important tool to address ecological and evolutionary aspects would be to have plant pairs that differ in only a single trait. Such plants are likely to become available in the near future as a result of mechanistic studies on signal-transduction pathways and an increased interest in molecular genetics.
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  • 12
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    Entomologia experimentalis et applicata 95 (2000), S. 141-149 
    ISSN: 1570-7458
    Keywords: ecology ; reproductive success ; fecundity ; intraspecific competition ; evolution ; pest outbreaks ; pest control ; chemical control ; economic threshold ; oilseed rape ; turnip rape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Populations of the rapeseed pollen beetle Meligethes aeneus F. (Col., Nitidulidae) from areas with 0–16 years of history of intensive rapeseed growing were compared for key ecological characters. During the first 16 years of rapeseed cultivation the reproductive success of M. aeneus increased 200–300% over that of the beetles living on the natural host plants, cruciferous weeds. The increase was linear over time and statistically highly significant, and it did not appear to be related to food quality or to the size of the beetles. During the same period the tolerance to intraspecific competition decreased, possibly due to the relative absence of such competition on the new crop. Furthermore, the optimum population density for M. aeneus to maximize the size of its next generation on summer turnip rape was determined to be 0.5–1.0 beetles/plant, which is slightly below the economic threshold for chemical control (1 beetle/plant). Therefore the practical protection of the rapeseed yield also ensures the highest possible pest population size for the next year. These mechanisms may in part explain the particular noxiousness of the species as a pest all over Europe. In general these data show that after the introduction of a new crop plant into a region, significant changes during the recruitment process in a pestiferous insect may take place, contributing to the future pest status of the insect. It is suggested that such genetic and ecological changes in insects may be a more common mechanism than previously thought in initiating and sustaining pest outbreaks, and that conventional pest management methods may enhance that effect.
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  • 13
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    Entomologia experimentalis et applicata 97 (2000), S. 339-346 
    ISSN: 1570-7458
    Keywords: crygenes ; PCR ; Lepidoptera ; Spodoptera ; insecticidal activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thirty-five strains of the entomopathogenic bacterium Bacillus thuringiensisactive on Spodoptera exigua, were characterized by means of serological identification and determination of crygene contents by PCR. The insecticidal activity of these 35 strains was further confirmed against S. exiguaand tested against two other species of the same genus: S. littoralisand S. frugiperda. The results indicate that serovars aizawai, thuringiensis, and kurstakiwere the most frequent within S. exigua-active strains and that serovar aizawaihad the highest number of strains exhibiting toxicity against the three species bioassayed. The presence in crygenes as determined by PCR suggests a non random distribution of some crygenes among serovars. Genes cry1C, cry1D, and cry1E, which are known to code for proteins toxic against Spodopteraspecies, were very common within S. exigua-active strains, specially in those belonging to serovar aizawai. However, some strains harbouring one or more of these genes were not toxic to S. littoralisor S. frugiperda; and some strains lacking all of the Spodoptera-active genes were found to be toxic to all three species. This suggests differences in the expression levels among strains bearing toxic genes and the involvement of other genes toxic to Spodopteraspecies. Since strains sharing the same crygenes exhibited different host ranges, the results indicate the need to perform toxicity bioassays in addition to other tests (serological identification and PCR) in order to determine the insecticidal activity of B. thuringiensisstrains.
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  • 14
    ISSN: 1572-8862
    Keywords: acetylene ion ; complex ; hydrogen ; nitrogen ; argon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The complexes formed by the positive acetylene ion with the hydrogen molecule, the nitrogen molecule, and the argon atom are investigated with ab initio calculations using the 6-311G** and the 6-31+G(2df,2pd) basis sets. MP2/6-311G** energies and optimum geometries are obtained, as well as single-point MP3, MP4, and QCISD(T) energies with the MP2/6-311G** optimized geometries. Single-point calculations are performed with the 6-31+G(2df,2pd) basis set at MP2/6-311G** optimized geometries.
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  • 15
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    Journal of insect behavior 13 (2000), S. 71-86 
    ISSN: 1572-8889
    Keywords: copulatory courtship ; behavioral interactions ; songs ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract D. birchii and D. serrata, two endemic Australian Drosophila species, have a copulatory courtship. The males of these species begin to court the female after mounting her and often go on with the courtship after the copulation is over. In the present paper we have described behavioral interactions between the male and the female and analyzed acoustic signals produced by the flies during courtship. Species differences were more pronounced in female than in male behavior. Variation within the species was obvious in the relative proportions of time the flies spent in different behaviors. Even though courtship took place nearly solely during copulation, some remains of precopulatory courtship were observed in both species. It is suggested that copulatory courtship exhibited by D. birchii and D. serrata flies is a derived rather than a primitive character.
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  • 16
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    Journal of insect behavior 13 (2000), S. 881-900 
    ISSN: 1572-8889
    Keywords: three-dimensional ; flight track recording ; orientation ; pheromones ; plant volatiles ; image analysis ; real time ; Lobesia botrana ; Lepidoptera ; Tortricidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A computer-controlled video system for real-time recording of insect flight in three dimensions is described. The flight paths of moths were recorded in a flight tunnel using two CCD cameras placed adjacent to each other at angles of 45 and 135° to the flight tunnel axis and separated by a distance of 120 cm. They were connected to two 28-level gray-scale frame grabbers via two external synchronizers. The two-dimensional coordinates of the flying insect were obtained from the two cameras at 40-ms intervals and transferred to host computer for processing and monitor for real-time display. Due to speed limitation in the image acquisition hardware, construction of the three-dimensional file was carried off-line. The flying insect was rendered as a dark spot in a bright background using a homogeneous light source. As the insect enters into the field of view of the two cameras, the light distribution changes, and the frame grabber detects only those variation in the light distribution which results from a flying insect. The target insect can be as small as 3 pixels and can be tracked in a stereoscopic field of view 60 cm long and 50 cm high. A method was developed that allowed for scalar scoring of various pheromone sources to assess their attractiveness using vector flight parameters. This method was applied successfully for optimization of pheromone blend of the grapevine moth, Lobesia botrana.
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    Adsorption 6 (2000), S. 137-147 
    ISSN: 1572-8757
    Keywords: adsorption ; kinetics ; linear driving force model ; process design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Linear Driving Force (LDF) model for gas adsorption kinetics is frequently and successfully used for analysis of adsorption column dynamic data and for adsorptive process designs because it is simple, analytic, and physically consistent. Yet, there is a substantial difference in the characteristics of isothermal batch uptake curves on adsorbent particles by the LDF and the more rigorous Fickian Diffusion (FD) model. It is demonstrated by using simple model systems that the characteristics of the adsorption kinetics at the single pore or the adsorbent particle level are lost in (a) evaluating overall uptake on a heterogeneous porous solid, (b) calculating breakthrough curves from a packed adsorbent column, and (c) establishing the efficiency of separation by an adsorptive process due to repeated averaging of the base kinetic property. That is why the LDF model works in practice.
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  • 18
    ISSN: 1572-879X
    Keywords: ammonia synthesis ; kinetics ; ruthenium catalysts ; promotional effect
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of NH3 synthesis over carbon-based ruthenium catalysts promoted with barium or alkali was studied. Both the ammonia partial pressure dependencies of the reaction rates (T = 400°C, p = 63 bar, H2 : N2 = 3 : 1) and the pressure variations of the activity (T = 370°C, p= 4–63 bar, H2 : NN2 = 3 : 1) were found to be different for Ba and for the alkali (K, Cs). Ba–Ru/C proved to be more sensitive to the NH3 content and to the total pressure. The rate of synthesis over the alkali-promoted catalysts is, in turn, much stronger influenced by the ruthenium dispersion. TOFs of NH3 synthesis for the promoted samples at 370°C and 4 bar (Ba 0.085 1/s, Cs 0.05 1/s, K 0.035 1/s) are significantly higher than that for the Ru(0001) basal plane (0.0085 1/s results from the literature data at 370°C, 2 bar). The most active Ru/C samples (Ba or Cs) exceed significantly the fused iron catalyst, especially at high conversions.
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  • 19
    ISSN: 1572-9028
    Keywords: rutile supported V2O5–WO3 catalyst ; evolution ; NO reduction
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    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper concerns the relation between surface structure of crystalline vanadia-like active species on vanadia–tungsta catalyst and their activity in the selective reduction of NO by ammonia to nitrogen. The investigations were performed for Ti–Sn-rutile-supported isopropoxy-derived catalyst. The SCR activity and surface species structure were determined for the freshly prepared catalyst, for the catalyst previously used in NO reduction by ammonia (320 ppm NO, 335 ppm NH3 and 2.35 vol% O2) at 573 K as well as for the catalyst previously annealed at 573 K in helium stream containing 2.35 vol% O2. The crystalline islands, exposing main V2O5 surface, with some tungsten atoms substituted for V-ones, were found, with XPS and FT Raman spectroscopy, to be present at the surface of the freshly prepared catalyst. A profound evolution of the active species during the catalyst use at 573 K was observed. Dissociative water adsorption on V5+OW6+ sites is discussed as mainly responsible for the catalyst activity at 473 K and that on both V5+OW6+ and V4+OW6+ sites as determining the activity at 523 K.
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  • 20
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    Topics in catalysis 11-12 (2000), S. 327-333 
    ISSN: 1572-9028
    Keywords: hydrodenitrogenation ; toluidine ; methylcyclohexylamine ; kinetics ; nickel-promoted molybdenum sulphide
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrodenitrogenation (HDN) of o-toluidine and its reaction intermediates was studied over a NiMo/γ-Al2O3 catalyst. The kinetics of the HDN of methylcyclohexylamine and of the hydrogenation of cyclohexene were also studied. Hydrogenation of o-toluidine alone produces methylcyclohexene and methylcyclohexane. When a sufficient quantity of cyclohexene is added during the HDN of toluidine, methylcyclohexylamine, the first intermediate in the hydrogenation of toluidine, becomes detectable. Because of its strong adsorption constant and high rate constant for reacting further to methylcyclohexene and methylcyclohexane, methylcyclohexylamine is not observed in the HDN of toluidine. Adding cyclohexene decreases the adsorption of methylcyclohexylamine, thus enabling its detection. The rate and adsorption constants of methylcyclohexylamine and cyclohexene in the HDN of methylcyclohexylamine were calculated by fitting the kinetic data to a Langmuir–Hinshelwood equation. A two-site model was used to describe the surface reactions, with one site for the methylcyclohexylamine reactions and the other for the cyclohexene reaction.
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  • 21
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    Adsorption 6 (2000), S. 349-357 
    ISSN: 1572-8757
    Keywords: sulfadiazene ; adsorption ; kinetics
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    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract To investigate the nature of interactive forces between sulfadiazene molecules and alumina surface the experiments were performed for the adsorption of sulfadiazene (SD) from its aqueous sulution onto the alumina surfaces at 25 ± 0.2°C and the influence of factors such as increasing concentration of SD (4.0–20.0 × 10−3 mol cm−3), the time required for adsorption equilibrium, pH (2.0–12.0) and temperature (5–45°C) of the adsorption medium, the presence of ions like Cl−, SO2− 4 and PO3− 4 (0.01–0.30 M) and organic solvents (5% v/v) were observed on the course of adsorption of SD. Various adsorption and kinetic parameters such as adsorption coefficient, the rate constants for adsorption and desorption were also evaluated. The results of the above cited studies facilitated to formulate the mechanisms of interaction between SD and alumina surfaces. From application view point the present work may be a potential tool for an effective chromatographic separation of sulfa drugs from industrial effluents.
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  • 22
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    Catalysis letters 64 (2000), S. 65-75 
    ISSN: 1572-879X
    Keywords: NO reduction ; CH3OH ; La2O3 ; methyl nitrite ; kinetics
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Nitric oxide (NO) reduction by methanol was studied over La2O3 in the presence and absence of oxygen. In the absence of O2, CH3OH reduced NO to both N2O and N2, with selectivity to dinitrogen formation decreasing from around 85% at 623 K to 50–70% at 723 K. With 1% O2 in the feed, rates were 4–8 times higher, but the selectivity to N2 dropped from 50% at 623 K to 10% at 723 K. The specific activities with La2O3 for this reaction were higher than those for other reductants; for example, at 773 K with hydrogen a specific activity of 35 μmol NO/s m2 was obtained whereas that for methanol was 600 μmol NO/s m2. The Arrhenius plots were linear under differential reaction conditions, and the apparent activation energy was consistently near 14 kcal/mol with CH3OH. Linear partial pressure dependencies based on a power rate law were obtained and showed a near‐zero order in CH3OH and a near‐first order in H2. In the absence of O2, a Langmuir–Hinshelwood type model assuming a surface reaction between adsorbed CH3OH and adsorbed NO as the slow step satisfactorily fitted the data, and the model invoking two types of sites provided the best fit and gave thermodynamically consistent rate constants. In the presence of O2 a homogeneous gas‐phase reaction between O2, NO, and CH3OH occurred to yield methyl nitrite. This reaction converted more than 30% of the methanol at 300 K and continued to occur up to temperatures where methanol was fully oxidized. Quantitative kinetic studies of the heterogeneous reaction with O2 present were significantly complicated by this homogeneous reaction.
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    Foundations of science 5 (2000), S. 429-456 
    ISSN: 1572-8471
    Keywords: awareness ; reflexive awareness and consciousness ; evolution ; experience and pattern matching ; symbolic language
    Source: Springer Online Journal Archives 1860-2000
    Topics: Natural Sciences in General
    Notes: Abstract An evolutionary point of view is proposed to make more appropriate distinctions between experience, awareness and consciousness. Experience can be defined as a characteristic linked closely to specific pattern matching, a characteristic already apparent at the molecular level at least. Awareness can be regarded as the special experience of one or more central, final modules in the animal neuronal brain. Awareness is what experience is to animals. Finally, consciousness could be defined as reflexive awareness. The ability for reflexive awareness is distinctly different from animal and human awareness and depends upon the availability of a separate frame of reference, as provided by symbolic language. As such, words have made reflexive awareness – a specific and infrequent form of awareness – possible. Conciousness might be defined as the experience evoked by considering, i.e. thinking about experiences themselves. If there is a hard problem of explaining consciousness, than this actually must be considered as the hard problem already met when trying to explain basic experience, since its nature remains elusive.
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    Catalysis letters 69 (2000), S. 103-107 
    ISSN: 1572-879X
    Keywords: dicyclopentadiene ; Wacker oxidation ; Pd(AcO)2 ; benzoquinone ; kinetics
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The oxidation of dicyclopentadiene catalyzed by palladium(II) acetate and benzoquinone in the presence of perchloric acid was studied. Tricyclodecenone in high selectivity (85–98%) at a conversion of dicyclopentadiene up to 76% was obtained. The kinetic model assumed the significant inhibition complexation between dicyclopentadiene and tricyclodecenone with the catalytic species.
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    Journal for general philosophy of science 31 (2000), S. 57-73 
    ISSN: 1572-8587
    Keywords: complex systems ; evolution ; nonlinearity ; pre-determination ; self-organization ; soft management ; structure-attractors ; synergetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Philosophy , Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract The philosophical consequences of synergetics, the interdisciplinary theory of evolution and self-organization of complex systems, are being drawn in the paper. The idea of discreteness of evolutionary paths is in the focus of attention. Although the future is open, and there are many alternative evolutionary paths for complex systems, not any arbitrary (either conceivable or desirable) evolutionary path is feasible in a given system. There are discrete spectra of possible evolutionary paths which are determined exclusively by inner properties of the corresponding systems. Synergetics allows us to reveal general laws of self-organization and, therefore, certain limits of arbitrariness of nature in choosing possible paths of evolution as well as in constructing of a complex evolutionary whole. A comparative analysis between the modern synergetic notions and a few ideas of the Western philosophy (F. Nietzsche, N. Hartmann, M. Heidegger) and of the Eastern teachings (Taoism, Buddhism) is made.
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    International journal of value-based management 13 (2000), S. 297-308 
    ISSN: 1572-8528
    Keywords: morality ; moral systems ; behavior ; evolution ; adaptation ; natural selection ; altruism ; reciprocal altruism ; fitness ; reciprocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract The ethical and moral behavior of Homo sapiens is no longer the exclusive domain of religion and philosophy because we recognize that such behavior affects the reproductive success of individuals within the species. We are a social species and therefore our survival is influenced by our capacity for cooperation and our willingness to take risks for kin. Emotions, some of which are found in other species, help to mediate our altruistic behavior. The reproductive benefits of helping kin, especially offspring, are readily seen. Helping non-kin can be beneficial if individuals can differentiate between ‘reciprocators’ and ‘non-reciprocators’ and direct altruistic behavior toward reciprocators. Also, if third parties are favorably impressed by observing altruistic behavior, the rewards need not come from the recipient of the altruistic behavior.
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  • 27
    ISSN: 1437-5613
    Keywords: Key words Herbivory ; Plant–herbivore interaction ; Lepidoptera ; Cruciferous plants ; Vegetation texture
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    Topics: Biology
    Notes: Abstract Correlation between plant size and reproductive output may be modified by herbivory in accordance with host plant density and the presence of nonhost plants. To elucidate the effects of nonhost plant density and host plant density on the intensity of herbivory and reproductive output of the host plant in relation to plant size under natural conditions, we investigated the abundance of three lepidopteran insects, Plutella maculipennis, Anthocharis scolymus, and Pieris rapae the intensity of herbivory, and fruit set of their host plant, Turritis glabra (Cruciferae). To elucidate the effects of nonhost and host plant density, we selected four categories of plots under natural conditions: low density of nonhost and high density of host plants; low density of both nonhost and host plants; high density of both nonhost and host plants; and high density of nonhost and low density of host plants. The plant size indicated by stem diameter was a good predictor of the abundance of all herbivorous species. The effects of density of nonhost and host plants on the abundance of insects varied among species and stages of insects. As the abundance of insects affected the intensity of herbivory, herbivory was more apparent on larger host plants in plots with low density of both nonhost and host plants. Consequently, the correlation between plant size and the number of fruits disappeared in low plots with density of both nonhost and host plants. In this T. glabra– herbivorous insect system, the density of nonhost plants and host plants plays an important role in modifying the relationship between plants and herbivores under natural conditions.
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  • 28
    ISSN: 1437-5613
    Keywords: Key words Community patterns ; Lepidoptera ; Route order ; Species richness ; Species distribution ; Environmental disturbance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Kitahara and Fujii, in 1994, analyzed the butterfly communities along a gradient of human disturbance by applying the generalist/specialist concept. Butterfly species were classified into generalist or specialist species based on their voltinism (seasonal time dimension) and potential larval resource breadth (food dimension). The community structure and species composition showed the systematic changes along the gradient. To verify the generality of those trends, we monitored five grassland butterfly communities with varying degrees of human disturbance twice a month during 1985 by the line transect method at the foot of Mt. Fuji, central Japan, and analyzed their structure in a manner similar to that employed by Kitahara and Fujii. Most results were consistent with the patterns recognized by Kitahara and Fujii. The route (community) order based on increasing human disturbance was strongly and negatively correlated with butterfly species richness but with neither butterfly species diversity (H′) nor evenness (J′). Also, the degree of human disturbance was significantly and negatively correlated with the number of specialist species, but not with that of generalists, in a community. Butterfly species richness was more strongly correlated with the number of specialist species than with that of generalists. Our analyses also showed that the generalist species were distributed more widely over the communities than were the specialists. However, in contrast to the trend revealed by Kitahara and Fujii, there was no significant difference in the population densities and in the spatial population variability between the two species groups. As a whole, our analyses confirmed the consistency of most community patterns detected by Kitahara and Fujii. The causes of the inconsistencies in some patterns were thought to be mainly the present habitat conditions with a relatively short growing season at high altitudes.
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    Nutrient cycling in agroecosystems 56 (2000), S. 59-68 
    ISSN: 1573-0867
    Keywords: bicarbonate-extractable potassium ; muriate of potash ; potassium ; potassium chloride ; relative effectiveness ; silicate rock powder ; Triticum aestivum ; Trifolium subterraneum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Granite (silicate) rock dust, a by-product of quarry operations, is being advocated and used as a fertilizer in the wheatbelt of south-western Australia (WA). The dust is insoluble and based on its nutrient element content (1.9% K and 0.3%P and negligible N) it is not expected to be a useful fertilizer. Previous laboratory studies and glasshouse experiments in WA suggest the dust is a slow release K fertilizer. This paper extends the previous studies to consider the dust as an NP or K fertilizer in the year of application in a field experiment on a soil deficient in N, P and K. In addition, the effectiveness of the dust as a K fertilizer was compared with the effectiveness of KCl (muriate of potash), the K fertilizer used in WA at present, in glasshouse experiments using K deficient soils. In the field experiment, compared with NP fertilizer or NPK fertilizer (urea, supplying N; superphosphate, providing P, S, Ca, Cu, Zn and Mo; KCl providing K), the dust had no effect on grain yield of wheat (Triticum aestivum); in fact dust applied at 20 t ha-1, for unknown reasons, reduced yields by about 65% compared to the nil (no fertilizer, no dust) treatment. Relative to the nil treatment, applying NPK fertilizer increased yields about threefold, from 0.54 to 1.79 t ha. The glasshouse experiments showed that, relative to KCl, the dust was from about 0.02 to 14% as effective in K deficient grey sandy soils for producing dried tops of 30-day old wheat plants or 42-day old clover (Trifolium subterraneum) plants. In soils with adequate K (yellow sands, sandy loams or clays, loamy clays, clay loams and clays), neither KCl nor the dust affected yields of 30 to 42-day old wheat or clover plants grown in the glasshouse. In the glasshouse experiments, no yield depressions were measured for the dust applied up to 17 g dust per kg soil (equivalent to 17 t dust ha-1 mixed into the top 10 cm of soil in the field). It is concluded that the dust has no value as a fertilizer.
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    Nutrient cycling in agroecosystems 56 (2000), S. 117-123 
    ISSN: 1573-0867
    Keywords: labelled nitrogen ; Lolium perenne ; nitrogen cycling ; root biomass ; straw ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Large amounts of nitrogen (N) fertiliser (150–200 kg N/ha) are currently being applied to perennial ryegrass (Lolium perenneL.) seed crops in New Zealand. Due to increasing requirements for efficient use of N fertilisers and minimising nitrate contamination of the environment, a field experiment was established using 15N-labelled fertiliser to follow the fate of applied N. Urea-15N was applied to a perennial ryegrass seed crop in April (30 kg N/ha), August (30 kg N/ha), September (60 kg N/ha) and October (60 kg N/ha). The urea-15N was applied in solution and watered in to minimise volatilisation loss. At the time of harvest (December), 9% of the applied 15N was in the seed, 29% in the straw, 19% in the roots and 39% in the soil organic matter. Losses of 15N were minimal as the N was applied in several applications, each one at a relatively low rate, and at times when leaching was unlikely to occur. Ryegrass plants used a greater proportion of the N applied in September and October (61–65%) compared with that applied in April (44%). Consequently more N was recovered from the soil in the autumn application (57%) than from the September and October applications (28–44%). The availability of the residual fertiliser N to a subsequent wheat (Triticum aestivum L.) crop was studied in a glasshouse experiment. The residual fertiliser N was present in the soil and ryegrass roots and stubble. The wheat plants only recovered 7–9% of this residual N. Most of the N taken up by the wheat came from the soil organic N pool. Overall, applying a total of 180 kg N/ha to the ryegrass appeared to have minimal direct impact on the environment. In the short term N not used by the ryegrass plants contributed to the soil organic N pool.
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    Nutrient cycling in agroecosystems 56 (2000), S. 139-152 
    ISSN: 1573-0867
    Keywords: nitrogen ; N leaching ; liquid manure ; catch crops ; N mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Results are presented from five years (1990–1995) of a field leaching experiment on a sandy soil in south-west Sweden. The aim was to study N leaching, change in soil organic N and N mineralization in cropping systems with continuous use of liquid manure (two application rates) and catch crops. N leaching from drains, N uptake in crops and mineral N in the soil were measured. Simulation models were used to calculate the N budget and N mineralization in the soil and to make predictions of improved fertilization strategies in relation to manure applications and changing the time for incorporation of catch crops. In treatments without catch crops, a normal and a double application of manure increased average N leaching by 15 and 34%, respectively, compared to treatment with commercial fertilizer. Catch crops reduced N leaching by, on average, 60% in treatments with a normal application of manure and commercial fertilizer, but only by 35% in the treatment with double the normal application rate of manure. Incorporation of catch crops in spring increased simulated net N mineralization during the crop vegetation period, and also during early autumn. In conclusion, manured systems resulted in larger N leaching than those receiving commercial fertilizer, mainly due to larger applications of mineral N in spring. More careful adaptation of commercial N fertilization with respect to the amounts of NH4-N applied with manure could, according to the simulations, reduce N leaching. Under-sown ryegrass catch crops effectively reduced N leaching in manured systems. Incorporating catch crop residues in late autumn instead of spring might be preferable with respect to N availability in the soil for the next crop, and would not increase N leaching.
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    Journal of insect conservation 4 (2000), S. 73-77 
    ISSN: 1572-9753
    Keywords: mapping ; database ; bias recording ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract We use data from the Mersey Valley zone (3×2 km area; N = 600 I ha squares) of the Greater Manchester butterfly atlas to investigate whether recorder visits are biased by access (viz. distance from recorder's home base) and by the locations of potential hot spots. In a multiple regression analysis, visits were found to correlate significantly both with distance from home base of the recorder and with the mean and maximum number of species found in squares. Sites close to the home base of the recorder were visited more frequently than those further afield and squares with more species were visited more frequently than those squares with fewer species. Visits were also made significantly more frequently to squares with greater numbers of butterfly resources (e.g. hostplants, nectar). Furthermore, recording is biased to and away from distinct land uses, which vary significantly in species richness. Reasons are given why these biases are to be expected at all scales. The message is that future distribution mapping should be based on rigorous sampling approaches.
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    Landscape ecology 15 (2000), S. 187-199 
    ISSN: 1572-9761
    Keywords: BOD5 ; catchment ; empirical model ; land use change ; land use scenarios ; nitrogen ; phosphorus ; runoff ; SO4
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Due largely to unprecedented land-use changes in the Porijõgi River catchment (southern Estonia) losses of nutrients and organic matter have decreased significantly. During the period 1987–1997 abandoned lands increased from 1.7 to 10.5% and arable lands decreased from 41.8 to 23.9%. At the same time, the runoff of total-N, total-P, SO4 and organic matter (after BOD5) decreased from 25.9 to 5.1, 0.32 to 0.13, 78 to 48, and 7.4 to 3.5 kg ha−1 yr−1, respectively. The most significant decreases occurred in agricultural subcatchments while the changes were insignificant in the forested upper course catchment. A simple empirical model which incorporates land-use pattern, fertilization intensity, soil parameters and water discharge accurately described the variations of total-N and total-P runoff in both the whole catchment and its agricultural subcatchments (R 2 varies from 0.95–0.99 for N to 0.49–0.93 for P). In small agricultural subcatchments the rate of fertilization is found the most important factor for nitrogen runoff, whereas in larger mosaic watersheds land use pattern plays the main role. Seven alternative scenarios compiled on the base of the empirical model allow to forecast potential nitrogen and phosphorus losses from the catchment. This information can be used in further landscape and regional planning of the whole region.
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  • 34
    ISSN: 1572-9737
    Keywords: conservation genetics ; Equus ; evolution ; mitochondrial DNA control region ; mitochondrial 12S rRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolution, taxonomy and conservation of the genus Equuswere investigated by examining the mitochondrial DNA sequences of thecontrol region and 12S rRNA gene. The phylogenetic analysis of thesesequences provides further evidence that the deepest node in thephylogeny of the extant species is a divergence between twolineages; one leading to the ancestor of modern horses (E.ferus, domestic and przewalskii) and the other to thezebra and ass ancestor, with the later speciation events of the zebrasand asses occurring either as one or more rapid radiations, or withextensive secondary contact after speciation. Examination of the geneticdiversity within species suggested that two of the E. hemionussubspecies (E. h. onager and E. h. kulan) onlyrecently diverged, and perhaps, are insufficiently different to beclassified as separate subspecies. The genetic divergence betweendomestic and wild forms of E. ferus (horse) and E.africanus (African ass) was no greater than expected within anequid species. In E. burchelli (plains zebra) there was anindication of mtDNA divergence between populations increasing withdistance. The implications of these results for equid conservation arediscussed and recommendations are made for conservation action.
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    Journal of the history of biology 33 (2000), S. 457-491 
    ISSN: 1573-0387
    Keywords: J. B. S. Haldane ; biology ; politics ; genetics ; evolution ; population genetics ; physiology ; Darwinism ; experimental biology ; eugenics ; Britain ; Russia ; India ; Soviet ; Communism ; socialism ; philosophy ; vision ; literature ; popularization ; religion ; human experimentation ; bioethics ; Venus ; Mars ; science fiction ; technocracy ; futurology ; H. G. Wells ; Julian Huxley ; Olaf Stapledon ; C. S. Lewis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract This paper seeks to reinterpret the life and work of J. B. S. Haldane by focusing on an illuminating but largely ignored essay he published in1927, “The Last Judgment” – the sequel to his better known work, Daedalus (1924). This astonishing essay expresses a vision of the human future over the next 40,000,000 years, one that revises and updates Wellsian futurism with the long range implications of the “new biology” for human destiny. That vision served as a kind of lifelong credo, one that infused and informed his diverse scientific work, political activities, and popular writing, and that gave unity and coherence to his remarkable career.
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    Journal of the history of biology 33 (2000), S. 221-246 
    ISSN: 1573-0387
    Keywords: August Weismann ; ciliates ; Clifford Dobell ; cytology ; death ; Emile Maupas ; evolution ; Herbert Spencer Jennings ; Otto Bütschli ; Paramecium ; rejuvenescence ; sex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Notes: Abstract In the period 1875–1920, a debate about the generality and applicability of evolutionary theory to all organisms was motivated by work on unicellular ciliates like Paramecium because of their peculiar nuclear dualism and life cycles. The French cytologist Emile Maupas and the German zoologist August Weismann argued in the 1880s about the evolutionary origins and functions of sex (which in the ciliates is not linked to reproduction), and death (which appeared to be the inevitable fate of lineages denied sexual conjugation), an argument rooted in the question of whether the ciliates and their processes where homologous to other cellular organisms. In the beginning of the twentieth century, this question of homology came to be less important as the ciliates were used by the British protozoologist Clifford Dobell and the American zoologist Herbert Spencer Jennings to study evolutionary processes in general rather than problems of development and cytology. For them, homology mattered less than analogy. This story illustrates two partially distinct problems in evolutionary biology: first, the question of whether all living things have common features and origins; and second, whether their history and current nature can be described by identical mechanisms. Where Maupas (contra Weismann) made the ciliates qualitatively the same as all other organisms in order to create a cohesive evolutionary theory for biology, Jennings and Dobell made them qualitatively different in order to achieve the same end.
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    Oecologia 122 (2000), S. 1-10 
    ISSN: 1432-1939
    Keywords: Key words Distribution ; Gregariousness ; Larval strategy ; Lepidoptera ; Thermoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Group-living in animal populations has many possible ecological and evolutionary explanations, including predator evasion and feeding facilitation. In insects, the thermal balance of solitary and gregarious larvae is likely to differ and may thus have important ecological consequences. The abilities of the larvae of four species of nettle-feeding nymphalid butterflies to thermoregulate were quantified in the field. Larval surface body temperatures of the gregarious Aglais urticae (small tortoiseshell) and Inachis io (peacock) and the solitary Polygonia c-album (comma) and Vanessa atalanta (red admiral) were measured for each instar, in both sunny and overcast conditions, over a seasonal range of temperatures. The results suggested two distinct larval thermal strategies. In the presence of direct sunlight, the exposed gregarious larvae of A. urticae and I. io regulated body temperatures at 32.5 and 31.5°C, respectively, while the temperatures of concealed larvae of P. c-album and V. atalanta were largely dependent on ambient temperatures. In the sun, the range of body temperatures recorded for A. urticae and I. io larvae was fairly narrow relative to ambient temperatures. This suggests a high degree of thermal control in these species. Modal body temperatures coincided with the temperature at which development rate is maximal. Regardless of whether changes in thermoregulation are a cause or consequence of the evolution of gregariousness, the combination of behavioural thermoregulation and gregariousness in larval insects has important implications for voltinism patterns and range extension (via increased development rates). Distributional responses of gregarious and solitary larvae to climatic warming may differ as a result of changes in cloud cover as well as changes in temperature.
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  • 38
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    Oecologia 122 (2000), S. 36-43 
    ISSN: 1432-1939
    Keywords: Key words Life history theory ; Longevity ; Ageing ; Mortality rate ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Life history theory predicts that organisms should only invest resources into intrinsic components of life span to the degree that it pays off in terms of reproductive success. Here, we investigate if the temporal distribution of mating opportunities may have influenced the evolution of intrinsic mortality rates in the butterfly Pararge aegeria (Satyrinae). In this species, females mate only once and the frequency of male mating opportunities depends on the temporal emergence pattern of virgin females. As expected, in a population from Madeira where females emerge continuously throughout the year, there was no sex difference in adult life span, while in a Swedish population with synchronised female emergence, males had significantly shorter life spans compared to females. A logistic mortality model provided the best fit to the observed change in age-specific mortality and all categories reached an asymptotic mortality rate of a similar magnitude. However, the Swedish males reached this mortality plateau more rapidly than the other categories. External mortality, due to water and food limitation, affected the pattern of sex-specific mortality but males from Sweden still had higher rates of mortality compared to all other categories. We argue that selection on male longevity is likely to be weaker in Sweden because under synchronised emergence, all females emerge and mate within a short period of time, after which male reproductive value will quickly approach zero. On Madeira, however, male reproductive value decrease more slowly with age since the probability of finding a receptive female is constant over the year.
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  • 39
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    Sciences of soils 5 (2000), S. 10-21 
    ISSN: 1432-9492
    Keywords: Soil temperature ; Triticum aestivum ; Stubble retention ; Nitrogen ; Early growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Early growth and development are often lower when wheat is sown into standing stubble. A study was conducted to determine whether this difference in early growth could be explained by the effects of stubble on soil temperature in the vicinity of the young plant. The roles of nitrogen nutrition and soil strength were also assessed. Three crops were monitored (1990–1992), with the wheat being sown into either standing wheat stubble after a no-till fallow (NT), or into no-tilled plots from which the stubble had been removed by burning (NB). Measurements were made of wheat growth and development, soil and plant N, soil temperature and penetration resistance. The site was on a black earth near Warialda in the northern wheatbelt of New South Wales, Australia. In 1992 wheat was also grown under simulated stubble to isolate the shading and soil temperature effects of stubble from other factors. A significant (P〈0.05) relationship was found between average soil temperature and above ground dry matter (DM) at 65 days after sowing (DAS) but not at 107 DAS. This relationship accounted for differences in DM production at 65 DAS between NT and NB treatments in 1991 and 1992, but not in 1990. In that year the lower DM production in NT plots was associated with poorer N nutrition, and possibly disease. Laboratory incubations indicate that immobilisation of N as stubble decomposed could have contributed to this. Burning stubble produced no immediate increase in soil N availability, so that it is unlikely that N contained in stubble contributed to the difference. Soil strength differences between treatments and phytotoxic effects are unlikely to have contributed to growth differences in this soil.
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  • 40
    ISSN: 1432-2242
    Keywords: Key words Glutenin ; Triticum aestivum ; Wheat storage proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Low-molecular-weight (LMW) glutenin subunits consist mainly of two domains, one at the N- terminus which contains repeats of short amino-acid motifs, and a non-repetitive one rich in cysteine, at the C- terminal region. In previous reports, polyacrylamide-gel electrophoresis has been used to show that large size variation exists among LMW and HMW glutenin subunits, and it has been suggested that deletions and insertions within the repetitive region are responsible for these variations in length. In this study, PCR-amplification of genomic DNA (Triticum aestivum variety Chinese Spring) was used to isolate three full-length LMW glutenin genes: LMWG-MB1, LMWG-MB2 and LMWG-MB3. The deduced amino-acid sequences show a high similarity between these ORFs, and with those of other LMW glutenin genes. Comparisons indicate that LMWG-MB1 has probably lost a 12-bp fragment through deletion and that LMWG-MB1 and LMWG-MB2 have an insertion of 81 bp within the repetitive domain. The current study has shown direct evidence that insertions and/or deletions provide a mechanistic explanation for the allelic variation, and the resultant evolution, of prolamin genes. Single-base substitutions at identical sites generate stop codons in both LMWG-MB2 and LMWG-MB3 indicating that these clones are pseudogenes.
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  • 41
    ISSN: 1432-2242
    Keywords: Key words Wheat ; High-molecular-weight glutenin ; AS-PCR ; Glu-A1 locus ; Null allele ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The present work reports new PCR markers that amplify the complete coding sequence of the specific alleles of the high molecular weight (HMW) glutenin genes. A set of AS-PCR molecular markers was designed which use primers from nucleotide sequences of the Glu-A1 and Glu-D1 genes, making use of the minor diffeences between the sequences of the x1, x2* of Glu-A1, and the x5 and y10 of Glu-D1. These primers were able to distinguish between x2* and the x1 or xNull of Glu-A1. Also x5 was distinguishable from x2, and y10 from y12. The primers amplified the complete coding regions and corresponded to the upstream and downstream flanking positions of Glu-A1 and Glu-D1. Primers designed to amplify the Glu-A1 gene amplified a single product when used with genomic DNA of common wheats and the xNull allele of this gene. This work also describes the cloning and characterisation of the nucleotide sequence of this allele. It possesses the same general structure as x2* and x1 (previously determined) and differs from these alleles in the extension of the coding sequence for a presumptive mature protein with only 384 residues. This is due to the presence of a stop codon (TAA) 1215-bp downstream from the start codon. A further stop codon (TAG), 2280-bp downstream from the starting codon is also found. The open reading frame of xNull and x1 alleles has the same size in bp. Both are larger than x2* which shows two small deletions. The reduced size of the presumptive mature protein encoded by xNull could explain the negative effect of this allele on grain quality.
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  • 42
    ISSN: 1432-2242
    Keywords: Keywords AFLPs ; Bulked segregant analysis ; Marker-assisted selection ; Microsatellites ; Powdery mildew resistance ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Molecular markers were identified in common wheat for the Pm24 locus conferring resistance to different isolates of the powdery mildew pathogen, Erysiphe graminis DM f. sp. tritici (Em. Marchal). Bulked segregant analysis was used to identify amplified fragment length polymorphism (AFLP) markers and microsatellite markers linked to the gene Pm24 in an F2 progeny from the cross Chinese Spring (susceptible)× Chiyacao (resistant). Two AFLP markers XACA/CTA-407 and XACA/CCG-420, and three microsatellite markers Xgwm106, Xgwm337 and Xgwm458, were mapped in coupling phase to the Pm24 locus. The AFLP marker locus XACA/CTA-407 co-segregated with the Pm24 gene, and XACA/CCG-420 mapped 4.5 cM from this gene. Another AFLP marker locus XAAT/CCA-346 co- segregated in repulsion phase with the Pm24 locus. Pm24 was mapped close to the centromere on the short arm of chromosome 1D, contrary to the previously reported location on chromosome 6D. Pm24 segregated independently of gene Pm22, also located on chromosome 1D. An allele of microsatellite locus Xgwm337 located 2.4±1.2 cM from Pm24 was shown to be diagnostic and therefore potentially useful for pyramiding two or more genes for powdery mildew resistance in a single genotype.
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    Theoretical and applied genetics 100 (2000), S. 32-38 
    ISSN: 1432-2242
    Keywords: Key words Waxy (Wx) protein ; Triticum aestivum ; Amylose content ; Starch ; Rapid Visco-Analyzer ; Swelling power ; Noodle quality
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    Topics: Biology
    Notes: Abstract  Waxy (Wx) protein is a granule-bound starch synthase (GBSS) responsible for amylose production in cereal endosperm. Eight isolines of wheat (Triticum aestivum L.) having different combinations of presence and absence of three Wx proteins, Wx-A1, -B1, and -D1, were produced in order to elucidate the effect of Wx protein deficiencies on the apparent amylose content and starch-pasting properties. An improved SDS gel electrophoresis showed that ’Bai Huo’ (a parental wheat) carried a variant Wx-B1 protein from an allele, Wx-B1e. Thus, wheat lines of types 1, 2, 4, and 6 examined in this study contained a variant Wx-B1 allele and not the standard allele, Wx-B1a. The results from 3 years of experiments using 176 lines derived from two cross-combinations showed that apparent amylose content increased the least in type 8 (waxy) having no Wx proteins and, in ascending order, increased in type 5 (only the Wx-A1 protein is present) 〈type 7 (Wx-D1) 〈type 6 (Wx-B1) 〈type 3 (Wx-A1 and -D1) 〈type 4 (Wx-A1 and -B1) 〈type 2 (Wx-B1 and -D1) 〈type 1 (three Wx proteins). However, Tukey’ s studentized range test did not detect significant differences in some cases. Densitometric analysis suggested that the amylose content was related to the amount of the Wx protein in the eight types. Parameters in the Rapid Visco-Analyzer test and swelling power were correlated to amylose content. Consequently, amylose content and pasting properties of starch were determined to be influenced the most by the lack of the Wx-B1 protein, followed by a lack of Wx-D1, and leastly by the Wx-A1 deficiency, which indicated the presence of differential effects of the three null alleles for the Wx protein.
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  • 44
    ISSN: 1432-2242
    Keywords: Keywords Composite populations ; Triticum aestivum ; Blumeria (Erysiphe) graminis f. sp. tritici ; Residual resistance effects ; Quantitative resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The evolution of adult plant resistance towards powdery mildew (caused by Blumeria graminis f. sp. tritici) was investigated in 11 wheat populations cultivated for 10 years in a French network for dynamic management (DM) of wheat genetic resources. The aims of the study were to compare the evolution of resistance in sites submitted to different powdery mildew pressure and to investigate the implication of specific resistance gene action in adult plant resistance. For this, 7 of the 11 populations were characterized for their composition of specific resistance genes (results presented in a former paper). Even though no population differed significantly from the initial PA0 pool for mean adult plant resistance, divergence appeared among the final populations. The populations with the highest adult plant resistance level originated from sites where powdery mildew pressure is known to be high (Vervins, Le Rheu), whereas populations with the lowest adult plant resistance corresponded to areas with no, or very low, powdery mildew pressure (Toulouse, Montreuil-Bellay). A residual effect of defeated specific resistance genes was hypothesized, as lines accumulating at least two specific resistance genes appeared more resistant. Additional quantitative resistance seemed to be involved in adult plant resistance. DM lines appeared then as an interesting source of variability for resistance towards powdery mildew. Moreover, as these lines had been grown in mixed populations they may be appropriate as components of a composite cultivar.
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  • 45
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    Theoretical and applied genetics 100 (2000), S. 519-527 
    ISSN: 1432-2242
    Keywords: Key words Wheat ; Triticum aestivum ; Physical mapping ; Deletion lines ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Extended physical maps of chromosomes 6A, 6B and 6D of common wheat (Triticum aestivum L. em Thell., 2n=6x=42, AABBDD) were constructed with 107 DNA clones and 45 homoeologous group-6 deletion lines. Two-hundred and ten RFLP loci were mapped, including three orthologous loci with each of 34 clones, two orthologous loci with each of 31 clones, one locus with 40 clones, two paralogous loci with one clone, and four loci, including three orthologs and one paralog, with one clone. Fifty five, 74 and 81 loci were mapped in 6A, 6B and 6D, respectively. The linear orders of the mapped orthologous loci in 6A, 6B and 6D appear to be identical and 65 loci were placed on a group-6 consensus physical map. Comparison of the consensus physical map with eight linkage maps of homoeologous group-6 chromosomes from six Triticeaespecies disclosed that the linear orders of the loci on the maps are largely, if not entirely, conserved. The relative distributions of loci on the physical and linkage maps differ markedly, however. On most of the linkage maps, the loci are either distributed relatively evenly or clustered around the centromere. In contrast, approximately 90% of the loci on the three physical maps are located either in the distal one-half or the distal two-thirds of the six chromosome arms and most of the loci are clustered in two or three segments in each chromosome.
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  • 46
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    Journal of thermal analysis and calorimetry 59 (2000), S. 633-642 
    ISSN: 1572-8943
    Keywords: cadmium ; dialkyldithiocarbamate ; kinetics ; thermal decomposition ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal decomposition kinetics of the solid complexes Cd(S2 CNR2 )2 , where R =C2 H5 , n -C3 H7 , n -C4 H9 or iso -C4 H9 , was studied by using isothermal and non-isothermal thermogravimetry. The superimposed TG/DTG/DSC curves revealed that thermal decomposition reactions occur in the liquid phase. The kinetic model that best fitted the experimental isothermal TG data was the one-dimensional phase-boundary reaction-controlled process R1 . The thermal analysis data suggested the thermal stability sequence Cd(S2 CNBun 2 )2 〉Cd(S2 CNPrn 2 )2 〉Cd(S2 CNBui 2 )2 〉Cd(S2 CNEt2 )2 , which accords with the sequence of stability of the apparent activation energies.
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    Journal of thermal analysis and calorimetry 59 (2000), S. 807-814 
    ISSN: 1572-8943
    Keywords: facial and meridional Co(III) complexes ; kinetics ; thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal properties of facial and meridional uns-cis-[Co(eddp)gly]0.5H2O complexes were investigated by means of DSC and TG techniques. It wasshown that the processes of thermal decomposition of these complexes are multi-stepdegradation processes, which can also be well separated into individual steps, depending onthe molecular symmetry. Thus, the process of thermal degradation of the meridional isomerof the above complex consists of 4 well-separated steps in the temperature interval from 100to 500°C. The corresponding kinetic and thermodynamic parameters of this process weredetermined, and a possible mechanism is discussed.
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    Journal of thermal analysis and calorimetry 61 (2000), S. 955-965 
    ISSN: 1572-8943
    Keywords: kinetics ; metal complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermogravimetry (TG) and differential thermal analysis (DTA) were performed on the complexes with general formula (M(DEBT)n (where M =Fe, Co, Ni, Cu or Ru; n =2, or 3 and DEBT=N,N-diethyl-N'-benzoylthiourea). Derivative thermogravimetric (DTG) curves were also recorded in order to obtain decomposition data on the complexes. The complexes of Fe(III), Co(II), Ni(II), Cu(II) and Ru(III) displayed two- or three-stage decomposition patterns when heated in a dynamic nitrogen atmosphere. Mass loss considerations relating to the decomposition stages indicated the conversion of the complexes to the sulfides or to the corresponding metal alone (Cu, Ru, NiS, CoS or FeS). Mathematical analysis of the TG and DTG data showed that the order of reaction varied between 0.395 and 0.973. Kinetic parameters such as the decomposition energy, the entropy of activation and the pre-exponential factor are reported.
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  • 49
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    Journal of thermal analysis and calorimetry 62 (2000), S. 429-433 
    ISSN: 1572-8943
    Keywords: adsorption ; fast measurement ; gravimetry ; kinetics ; sorption ; kw6
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Jäntti introduced a method to reduce the time required for the stepwise measurement of adsorption isotherms. After each pressure change he measured the adsorbed mass three times and calculated its equilibrium value at the new pressure. In the present paper, we discuss the applicability of this method in a broader scope without starting from a given combination of sorptive and adsorbent and the influence of measuring inaccuracies. The method is applied to detect whether the adsorption process is based on more than one adsorption mechanism or not.
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  • 50
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    Journal of thermal analysis and calorimetry 63 (2000), S. 375-386 
    ISSN: 1572-8943
    Keywords: activation energy ; ammonium perchlorate ; decompositon ; isothermal ; kinetics ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of the thermal decomposition of ammonium perchlorate at temperatures between 215 and 260°C is studied, in this work, by measuring the sample mass loss as a function of time applying the isothermal thermogravimetric method. From the maximum decomposition rate – temperature dependence two different decomposition stages, corresponding to two different structural phases of ammonium perchlorate, are identified. For the first region (215–235°C), corresponding to the orthorhombic phase, the mean value of the activation energy of 146.3 kJ mol–1, and the pre-exponential factor of 3.43⋅1014 min–1 are obtained, whereas for the second region (240–260°C), corresponding to the cubic phase, the mean value of the activation energy of153.3 kJ mol–1, and the pre-exponential factor of 4.11⋅1014 min–1 are obtained.
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    Journal of thermal analysis and calorimetry 60 (2000), S. 35-43 
    ISSN: 1572-8943
    Keywords: kinetics ; 10-methylacridinium halides ; thermodynamics ; thermogravimetric investigations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 10-Methylacridinium chloride, bromide and iodide were prepared in crystalline forms (the first two salts as monohydrates) and subjected to thermogravimetric investigations. Decomposition of the compounds is initially accompanied by the liberation of water (in case of monohydrates), halomethanes and acridine molecules. As decomposition proceeds, side reactions occur which are reflected in a complex pattern of thermogravimetric curves. TG traces corresponding to the initial decomposition stage were used to determine the kinetic characteristics of the thermal dissociation of the salts. MNDO/d, AM1 and PM3 methods were employed independently to examine reaction pathways and to predict thermodynamic and kinetic barriers for the thermal decomposition of the compounds. These data were subsequently supplemented with theoretically determined crystal lattice energies, which enabled the relevant characteristics for the decomposition of crystalline phases to be predicted. The theoretically predicted characteristics are qualitatively comparable with those originating from thermogravimetric investigations, which allows one to believe that both are valid.
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  • 52
    ISSN: 1572-8943
    Keywords: cyanazine ; DSC ; kinetics ; thermal stability
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Cyanazine was taken as an example for investigations under the influence of different conditions on thermal decomposition of triazine herbicides. DSC measurements were carried out under atmospheric pressure and hermetically closed, under pressure 1.3 kPa. The influence of the pressure on the constant reaction rate of decomposition of cyanazine was discussed. It was also proved that the predicted reaction constant rates from isothermal and non-isothermal measurements are consistent.
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    Journal of thermal analysis and calorimetry 60 (2000), S. 247-255 
    ISSN: 1572-8943
    Keywords: desulfuration ; gas atmosphere ; kinetics ; thermal decomposition ; titanium dioxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The studies were devoted to determination of the effect of gas atmosphere and its pressure on the second step of decomposition of hydrated titanium dioxide (HTD) promoted by sulfate groups. It has been found that thermal decomposition of HTD at temperatures above 300°C consists of a number of processes such as dehydroxylation, desulfuration, recrystallization and sintering of solid grains, photochemical processes (if the decomposition proceeds in the presence of light) and adsorption of gas phase components (in the presence of air or SO2). Kinetic parameters characterizing this step of decomposition have been determined for processes carried out in vacuum and in argon or air atmospheres (at a pressure of 13.33hPa). The kinetic curves of decomposition carried out in the presence of gases capable of being adsorbed on the surface of partly dehydrated HTD are featured by local extrema due to simultaneous processes of decomposition and adsorption of gas components.
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    Journal of thermal analysis and calorimetry 60 (2000), S. 9-15 
    ISSN: 1572-8943
    Keywords: coordination compounds ; kinetics ; thermal dissociation
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Physicalo-chemical importance of the quantitative study of kineticliability of coordination compounds in thermal dissociation processes is considered. Muchattention is given to the proof of the physicalo-chemical meaning and validity of kineticparameters calculated from thermoanalytical data. Experimental data (thermal dissociation ofcoordination compounds and clathrates with such a matrix) are discussed.
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    Journal of thermal analysis and calorimetry 60 (2000), S. 401-407 
    ISSN: 1572-8943
    Keywords: cross-linking ; isothermal crystallization ; kinetics ; modification ; polypropylene ; silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of addition of silica on the parameters of isothermal crystallization of polypropylene has been investigated. It was found that the covering of the silica surface by a layer of low-density polyethylene leads to a deactivation of the filler regarding the positive effect on the polypropylene crystallization rate parameters. Cross-linking of the surface polyethylene layer results in a stronger attachment of the modifying polymer to the filler surface and the deactivation effect of the silica surface modification is more pronounced.
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    Journal of thermal analysis and calorimetry 60 (2000), S. 541-547 
    ISSN: 1572-8943
    Keywords: Cr(II) ; chromium trioxide ; kinetics ; reduction ; thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal behaviour of CrO3 on heating up to 600°C in dynamic atmospheres of air, N2 and H2 was examined by thermogravimetry (TG), differential thermal analysis (DTA), IR spectroscopy and diffuse reflectance spectroscopy (DRS). The results revealed three major thermal events, depending to different extents on the surrounding atmosphere: (i) melting of CrO3 near 215°C (independent of the atmosphere), (ii) decomposition into Cr2(CrO4)3 at 340–360°C (insignificantly dependent), and (iii) decomposition of the chromate into Cr2O3 at 415–490°C (significantly dependent). The decomposition CrO3 → Cr2(CrO4)3 is largely thermal and involves exothermic deoxygenation and polymerization reactions, whereas the decomposition Cr2(CrO4)3 → Cr2O3 involves endothermic reductive deoxygenation reactions in air (or N2) which are greatly accelerated and rendered exothermic in the presence of H2. TG measurements as a function of heating rate (2–50°C min−1) demonstrated the acceleratory role of H2, which extended to the formation of Cr(II) species. This could sustain a mechanism whereby H2 molecules are considered to chemisorb dissociatively, and then spillover to induce the reduction. DTA measurements as a function of the heating rate (2–50°C min−1) helped in the derivation of non-isothermal kinetic parameters strongly supportive of the mechanism envisaged.
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    Journal of thermal analysis and calorimetry 60 (2000), S. 667-674 
    ISSN: 1572-8943
    Keywords: accommodation function ; crystal growth ; glass-ceramics ; kinetics ; number of nuclei ; thermal history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Kinetic modeling of the crystal growth from pre-existing nuclei was reexamined to obtain a fundamental information about the controlled crystallization of glasses during formation of advanced inorganic glass-ceramics. Methods of kinetic analysis were reviewed by taking account of thermal history of the sample within the temperature range of nucleation. An accommodation function depending on the thermal history was introduced in the kinetic equation. The role of the accommodation function was reinvestigated when determining the activation energy from a series of kinetic curves. The kinetic description of the crystal growth in the samples with different thermal history was generalized by extrapolating the rate behavior to infinite temperature.
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    Journal of thermal analysis and calorimetry 60 (2000), S. 333-343 
    ISSN: 1572-8943
    Keywords: base line ; DSC ; kinetics ; modeling ; thermodynamics ; TMDSC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The application of non-linear heating program to a heat-flux DSC apparatus has attracted much attention. From thermodynamics viewpoint, it is shown that the variation of enthalpy of a sample changing with temperature change is due, to both the true heat capacity of the sample and the enthalpy of some transformations occurring in the sample, characterized by its degree of advance. Using the simple assumption that the rate of the transformation is proportional to the distance from the thermodynamic equilibrium, an electrical model of the thermal event is given. Using the coupled cell model of the DSC apparatus, we show how to obtain the rate of transformation of the sample and heat capacity, which is directly related to the base line of the experiment.
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  • 59
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    Journal of thermal analysis and calorimetry 60 (2000), S. 759-778 
    ISSN: 1572-8943
    Keywords: decomposition temperature ; error sources ; gas-flow and vapor control ; kinetics ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The well-known divergence between the present ‘state of the art’ of thermogravimetry and industrial requirements is discussed. Sources of errors are analyzed and the optimization of measuring conditions is discussed regarding the problems associated with static and dynamic (flow) atmospheres, and interactions between materials and gases or vapors. Recommendations for gas-flow control systems and vapor sources are given. Thermal stability and the kinetics of gas-evolving, reversible, thermal decompositions of solids are discussed. The scope of TG-derived kinetics for practical use is examined. Some new characteristic points of TG curves are proposed and defined, e.g. ‘procedure-independent decomposition temperature’ and ‘augmented decomposition temperature’ (obtained at pseudo-equilibrium conditions).
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  • 60
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    Journal of thermal analysis and calorimetry 60 (2000), S. 879-886 
    ISSN: 1572-8943
    Keywords: driving force ; kinetics ; rate equation ; reversible reactions
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    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper outlines the different ways of taking the distance from thermodynamic equilibrium into account in kinetic studies based on thermoanalytical experiments. The three main approaches are: (i) avoiding or neglecting the effect of the reverse reaction, (ii) describing the influence of distance from equilibrium on apparent kinetic parameters, and (iii) incorporating a driving force factor in the rate equation. Finally, the contradiction of the microscopic nature of the processes and the macroscopic character of the usual rate equation are briefly discussed.
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  • 61
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    Journal of thermal analysis and calorimetry 60 (2000), S. 943-954 
    ISSN: 1572-8943
    Keywords: CRTA ; kinetics ; self-generated atmospheric conditions ; synthetic malachite ; thermal decomposition
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetic behavior of the thermal decomposition of synthetic malachite was investigated by means of CRTA under different conditions of reduced pressure, flowing gases and quasi-isobaric atmospheres. The thermal decomposition was found to proceed at lower temperatures under the influence of the self-generated gases, CO2 and H2O. From a viewpoint of chemical equilibrium, the normal and opposite effects on the overall kinetics were observed for the self-generated CO2 and H2O, respectively. The complexity of the present reaction is also reflected by the variations of the apparent kinetic parameters which depend on the applied and self-generated atmospheric conditions. The practical usefulness of CRTA when applied to a complicated thermal decomposition is discussed as exemplified by the kinetic approaches to the present reaction.
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  • 62
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    Journal of thermal analysis and calorimetry 61 (2000), S. 151-156 
    ISSN: 1572-8943
    Keywords: complexes ; kinetics ; TG-DTA
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal behaviour of a few lanthanide complexes of the type ML3(I) [M=Eu,Gd; HL=4,4,4-trifluoro- 1-(2-napthyl)-1,3-butanedione and EuL30.5dmm dmm=2,6-dimethylmorpholine(II)], has been investigated. From thermogravimetric(TG) curves, the decomposition pattern of the compounds has been analysed on the basis of mass loss data. The order and activation energy of the thermal decomposition reactions have been elucidated. From differential thermal analysis (DTA) studies, the heat of reaction and rate of thermal decomposition reaction have been enumerated.
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  • 63
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    Journal of thermal analysis and calorimetry 61 (2000), S. 239-242 
    ISSN: 1572-8943
    Keywords: kinetics ; Mannich compounds ; thermal decomposition
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The authors present data concerning the evaluation of kinetic parameters of the decomposition of a Mannich compound by using the classical method of constant heating rate thermal analysis and the new one of controlled rate thermal analysis (CRTA). The data processed using the CRTA method allow to obtain more reliable kinetic parameters according to the proposed reaction mechanism.
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  • 64
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    Journal of thermal analysis and calorimetry 61 (2000), S. 437-450 
    ISSN: 1572-8943
    Keywords: crystallization ; EPDM ; kinetics ; morphology ; PP ; rubber
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of the incorporation of an amorphous immiscible polymer (ethylene-propylene-diene- terpolymer) on the PP crystallization kinetics and thermodynamics is investigated by thermal analysis. The results of the investigation have shown that EPDM acts as a nucleant agent. A marked decrease of the half time of PP crystallization, τ1/2 , as well as a sensible increase of the overall crystallization rate, K n , has been observed in the presence of EPDM. Moreover, at any crystallization temperature, a minimum of τ1/2 , is obtained at 25% EPDM content in the blend. The Avrami model has been successfully applied to describe the crystallization kinetics of the blend. The kinetic curves obtained under non-isothermal conditions confirm the results obtained under isothermal conditions and demonstrate the nucleant action of the EPDM phase on the PP crystallization.
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  • 65
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    Journal of thermal analysis and calorimetry 62 (2000), S. 721-727 
    ISSN: 1572-8943
    Keywords: kinetics ; metal exchange ; thermaldehydration ; zeolite
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Zeolite-4A is a hydrated aluminosilicate which becomes more hydrated when exchanged with transition metals. In this work, the dehydration kinetics of cobalt, nickel and copper(II)-exchanged zeolite-4A were studied by means of TG and DTA over the temperature range from 20 to 500°C, and the numbers of water molecules in the metal-exchanged zeolite samples were calculated. It was observed that, as the ionic radius of the hydrated metal increased, the number of water molecules also increased. The loss of water from the zeolite samples generally occurred in the temperature range 100–300°C and was manifested in the DTA graphs by an extended endothermic effect. The DTA curves demonstrated that the peak position shifted towards lower temperatures as the metal concentration increased or, in other words, the water of hydration increased. The kinetic parameters (order of reaction and activation energy) were calculated via the Coats and Redfern method. The process of dehydration was found to follow first-order kinetics.
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  • 66
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    Journal of thermal analysis and calorimetry 63 (2000), S. 359-374 
    ISSN: 1572-8943
    Keywords: KEKAM equation ; kinetics ; thermal dissociation of solids
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Relationships have been established between the average conversion degree and the dissociation time for polydisperse granular material, taking its grain size distribution into account. It has been checked in which cases the kinetic curves obtained by a numerical solution can be described in terms of KEKAM equation.
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  • 67
    ISSN: 1572-8943
    Keywords: isoconversional methods ; kinetics
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    Topics: Chemistry and Pharmacology
    Notes: Abstract An analysis is presented of the consequences of the use of a one term equation containing apparent activation parameters, instead of the true rate equation to describe two successive decomposition reactions undergone by a solid compound. It is demonstrated that the apparent activation energy, obtained by means of isoconversional differential and integral methods, varies with the conversion degree for a relatively narrow temperature range and with temperature at a given value of the conversion degree. The activation energy values obtained with the isoconversional differential method are higher than the corresponding values obtained with the isoconversional integral method.
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  • 68
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    Journal of thermal analysis and calorimetry 59 (2000), S. 869-875 
    ISSN: 1572-8943
    Keywords: decomposition ; kinetics ; plumbo-jarosite
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    Topics: Chemistry and Pharmacology
    Notes: Abstract An investigation was carried out on the kinetics of thermal decomposition of plumbo-jarosite. The kinetic models of dissociation of the compounds in the ore were identified. The results of the kinetic studies and the mechanism of the process are discussed. The thermal decomposition of plumbo-jarosite occurs in three stages: the first up to 763, the second up to 1023 and the third up to 1223 K, the corresponding activation energy values being 62.2, 60.3 and 98.0 kJ mol–1 , respectively.
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  • 69
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    Journal of thermal analysis and calorimetry 61 (2000), S. 805-818 
    ISSN: 1572-8943
    Keywords: aluminium ; ARC ; DSC ; kinetics ; nanometric size ; SDT ; TG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal properties of Alex, a nanosized Al powder, were determined using various techniques, including DSC, TG, simultaneous TG-DTA (SDT) and accelerating rate calorimetry (ARC). The results demonstrate that the specific heat capacities of nano and micron size Al powders are similar between 30 and 400°C. Dynamic and isothermal methods were used to determine the kinetic parameters for the oxidation reaction of Alex, which was detected at an onset temperature of 481°C. The results obtained were in good agreement with each other. From the ARC experiments, exotherms were detected near 340 and 260°C for experiments started at ambient pressure and at 0.72 MPa, respectively.
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  • 70
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    Journal of thermal analysis and calorimetry 61 (2000), S. 861-871 
    ISSN: 1572-8943
    Keywords: DAGN ; kinetics ; mechanism and IR spectroscopy ; TAGN ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Diaminoguanidine nitrate (DAGN) and triaminoguanidine nitrate (TAGN),potential energetic materials in emerging propulsion technology with high mass impetus at low isochoric flame temperature have been studied as regards kinetics and mechanism of thermal decomposition using thermogravimetry (TG), differential thermal analysis (DTA),infrared spectroscopy (IR) and hot stage microscopy. Kinetics of thermolysis has been followed by isothermal TG and IR. For the initial stage of thermolysis of DAGN the best linearity with a correlation coefficient of 0.9976 was obtained for the Avrami-Erofe'evequation, n=2, by isothermal TG. The activation energy was found to be 130 kJ mol–1 and logA=11.4. The initial stage of thermolysis of TAGN also obeyed the Avrami-Erofe'ev equation, n=2, with a correlation coefficient of 0.9975by isothermal TG and the kinetic parameters are E=160.0 kJ mol–1 and logA=16.0. High temperature IR spectra showed exquisite preferential loss in intensity of the NH2, NH, N–N stretching and CNN bending. Spectroscopic and other results favour deamination reaction involving the rupture of the N–N bond as the primary step in the thermal decomposition.
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    Journal of thermal analysis and calorimetry 61 (2000), S. 979-984 
    ISSN: 1572-8943
    Keywords: kinetics ; nucleation-growth
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The author presents some applications of the fractal geometry in the kinetics of heterogeneous decomposition of solids.
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  • 72
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    Journal of thermal analysis and calorimetry 59 (2000), S. 935-942 
    ISSN: 1572-8943
    Keywords: CoSO46H2O ; kinetics ; thermal decomposition
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermogravimetry (TG-DTG), and differential thermal analysis (DTA) were used in the study of the kinetics of decomposition of cobalt sulphate hexahydrate under an air atmosphere. The kinetics of the particular stages of CoSO4 6H2 O decomposition were evaluated from the dynamic mass loss data. The values of the kinetic parameters for each stage of the thermal decomposition were calculated from the α(T) data by using the integral method, applying the Coats-Redfern approximation.
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  • 73
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    Journal of thermal analysis and calorimetry 62 (2000), S. 681-685 
    ISSN: 1572-8943
    Keywords: coal-burning additive ; combustion ; graphite ; kinetics
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The catalytic and accelerating effects of three coal-burning additives (CBA) on the burning of graphite were studied with the help of thermogravimetric (TG) analysis. The kinetic study on the catalytic oxidation of the graphite doped with CBA was carried out and the results were presented. The results show that the CBA can change the carbon oxidation/combustion course by catalytic action and change the activation energy, thus improving the combustion efficiency.
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  • 74
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    Journal of thermal analysis and calorimetry 63 (2000), S. 457-463 
    ISSN: 1572-8943
    Keywords: isoconversional methods ; kinetics
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    Topics: Chemistry and Pharmacology
    Notes: Abstract It is demonstrated that, if the activation energy depends on the degree of conversion, its values obtained by isoconversional differential and integral methods are different.
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  • 75
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    Plasma chemistry and plasma processing 20 (2000), S. 87-110 
    ISSN: 1572-8986
    Keywords: striations ; nitrogen ; spherical discharge ; spatially inhomogeneous Boltzmann equation ; electron velocity distribution function ; dc glow discharge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Recent observations of spherical striations in large-volume nitrogen dcdischarges with a central anode have stimulated investigations of thenonlocal electron kinetics in these striations by solving the spatiallyinhomogeneous Boltzmann equation adapted to spherical geometry. Becausethe radial course of the electric potential is largely unknown in thisdischarge, different models concerning its radial course have been developedand used. These models are based on the measured radii of the striationsand the assumption that the potential drop between successive striationsdoes not change. As a consequence, with decreasing distance between thestriations the electric field strongly increases toward the centralanode. It has been found that spherical striations are only obtained ifthe electric field is strongly modulated. In this case, a highly nonlocalbehavior of the velocity distribution function and strongly modulatedradial courses of the macroscopic quantities have been obtained.
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  • 76
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    Journal of materials synthesis and processing 8 (2000), S. 139-144 
    ISSN: 1573-4870
    Keywords: TiO2 ; phase transformations ; mechanical alloying ; kinetics ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A high-pressure and high-temperature phase of TiO2 : TiO2 II is formed transiently during room-temperature high-energy ball milling of anatase TiO2 : TiO2 anatase → TiO2 II → TiO2 rutile. Rutile is the only phase present after prolonged ball milling. The present paper focuses on the influences of physical and chemical processing conditions on the transformation kinetics. The effects of two milling parameters on the kinetics of phase transformation of anatase TiO2 were investigated: the nature of milling tools and the powder-to-ball weight ratio R. Granulometric characterizations and TEM observations have demonstrated that the transformation of TiO2 anatase into TiO2 II occurs without fracturing of particles and that TiO2 II nanograins form at the surface of anatase particles. The parameter R affects only the transformation rate. For a given R, the transformation rate is the largest with alumina grinding tools, intermediate with zirconia tools, and the smallest with steel tools. The parameters involved in current models of the mechanical alloying process do not suffice to explain the differences in transformation rates observed here. A parameter, which takes into account the influence of the mechanical properties of grinding materials, is considered.
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  • 77
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    Journal of materials synthesis and processing 8 (2000), S. 271-277 
    ISSN: 1573-4870
    Keywords: Comminution ; kinetics ; mechanical alloying ; phase transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract It has been shown that structural evolution occurring in powder mixtures subjected to mechanical treatment by milling follow well-defined conversion trends as a function of milling time. Sigmoidal curves were observed in the case of the mechanical alloying of transition metal mixtures, whereas a simpler kinetic course with a progressively decreasing transformation rate was found to characterize the disordering process of intermetallic equilibrium compounds by mechanical milling. Under the stipulation that collisions are the dominant energy transfer events, a kinetic model is developed to relate the observed macrokinetic features to the discrete powder fractions, which transform at each impact. Because of its intrinsic qualities, the milling process was regarded as discrete processing. A statistical approach was followed to work out a set of differential equations, solutions of which provide a sound description of the transformation kinetics in terms of conventional rate expressions. The model allows one to reproduce the different kinetic behaviors by means of a single, unifying mathematical formalism. Furthermore, quantifying the structural evolution rate by suitable kinetic constants permits the exploration of the reactive behavior of a system treated under different milling regimes or to compare, on an absolute basis, different systems processed under similar conditions.
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  • 78
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    Oxidation of metals 53 (2000), S. 351-360 
    ISSN: 1573-4889
    Keywords: Co-base superalloy ; high-temperature oxidation ; kinetics ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of the Co-base superalloy DZ40M was studied in air at900–1100°C for times of up to 2000 hr. The results indicated thatthis alloy can grow a protective oxide scale at 900 and 1000°C duringisothermal oxidation, but not at 1100°C because of serious cracking andspalling of the oxide scales. Moreover, an internal-precipitate zone formedin the subsurface region of the alloy at all temperatures and times. Theprecipitates were rich in Cr in the vicinity of the alloy–scaleinterface and rich in Al deep in the alloy. The internal-precipitatemorphology changed from a granular to needlelike shape with increasingoxidation temperature.
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  • 79
    ISSN: 1573-1561
    Keywords: Insect pheromones ; pheromone emission ; aggressive chemical mimicry ; predation ; allomone ; Araneae ; Araneidae ; Lepidoptera ; Noctuidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The adult female bolas spider Mastophora hutchinsoni feeds exclusively on attracted males of a few moth species. This exclusivity and the behavior of the approaching moths suggest that the spider aggressively mimics the sex pheromones of its prey species. Males of the bristly cutworm, Lacinipolia renigera, are a major prey of this spider, accounting for about two thirds of the biomass of prey consumed. Female bristly cutworms produce a pheromone blend consisting of (Z)-9-tetradecenyl acetate (Z9–14 : Ac) and (Z,E)-9,12-tetradecenyl acetate (ZE-9,12–14 : Ac). To determine if M. hutchinsoni females mimic the sex pheromone components and blend ratio of L. renigera, we collected volatiles from hunting adult female spiders and analyzed them with gas chromatography–electroantennographic detection (GC-EAD) and gas chromatography–mass spectrometry (GC-MS). GC-EAD analysis of volatile collections, using a male bristly cutworm antenna as the detector and two capillary columns of different polarities, revealed the presence of peaks with retention times (R ts) identical to Z9–14 : Ac and ZE-9,12– 14 : Ac. The mass spectrum of a peak with R t of Z9–14 : Ac was identical to the mass spectrum of the synthetic equivalent. There was an insufficient quantity of the compound with R t of ZE-9,12–14 : Ac to get a full spectrum, but selective detection of ions at m/z 61 and 192 at the correct R t supported the identification. On average, the blend collected from spiders contained 54.8 ± 20.8 (SE) pg/min of Z9–14 : Ac and 2.5 ± 1.7 (SE) pg/min of ZE-9,12–14 : Ac. The latter, on average, comprised 2.6 ± 0.7% of the total, which is similar to the blend ratio emitted by bristly cutworm females. Our results indicate that the adult female M. hutchinsoni produces an allomone blend that mimics not only the composition, but also the blend ratio, of the sex pheromone of a major prey species.
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  • 80
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    Journal of chemical ecology 26 (2000), S. 1749-1763 
    ISSN: 1573-1561
    Keywords: Conversion factor ; free amino acids ; fruits ; Kjeldahl ; nitrogen ; nutrition ; protein ; pulp ; secondary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Protein content of plant tissues is usually estimated by multiplying total nitrogen by a conversion factor of 6.25. This technique assumes that all nitrogen originates from protein. When applied to fruit pulp, it overestimates protein content because pulp typically contains free amino acids and many nitrogenous secondary metabolites. At issue is the extent of error and, consequently, what the conversion factor between nitrogen and protein should be. We calculated a conversion factor based on pulp samples from 18 species collected in the southeastern United States. We also report a new and simple method of estimating protein and free amino acids in fruit pulp. Because previous studies have found high variation in protein and secondary metabolite content among fruit species, use of a single conversion factor for all species will generate error. In an attempt to reduce such error, we calculated protein contents and conversion factors separately for two common fruit types: lipid-rich/carbohydrate-poor and lipid-poor/carbohydrate-rich. We found no difference between these types of fruit and hence combined results in calculating an average conversion factor of 5.64. Use of an accurate conversion factor is important in estimating protein consumption by wild animals and in formulating diets of captive animals. It can also reveal whether loss of body mass in captive animals on fruit diets is due to insufficient protein consumption, secondary metabolite toxicity, or an imbalance of amino acids.
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  • 81
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    Journal of chemical ecology 26 (2000), S. 1983-1990 
    ISSN: 1573-1561
    Keywords: Setora nitens ; Setothosea asigna ; nettle caterpillar ; Limacodidae ; Lepidoptera ; sex pheromone ; (Z)-9-dodecenal ; (Z)-9,11-dodecadienal ; (E)-9-dodecenal ; (E)-9,11-dodecadienal ; oil palm ; Elaeis guineensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Gas chromatographic–electroantennographic detection (GC-EAD) analyses of pheromone gland extracts of female nettle caterpillars, Setora nitens, revealed four compounds that consistently elicited responses from male moth antennae. Retention indices on three fused silia columns (DB-5, DB-23, and DB-210) of two EAD-active compounds were almost identical to those of (E)-9-dodecenal (E9–12 : Ald) and (E)-9,11-dodecadienal (E9,11–12 : Ald), two pheromone components previously identified in congeneric Setothosea asigna. However, comparative GC, GC-EAD, and GC-mass spectrometry of extracted S. nitens compounds and authentic standards revealed that the candidate pheromone components were (Z)-9-dodecenal (Z9–12 : Ald) and (Z)-9,11-dodecadienal (Z9,11–12 : Ald). The two other EAD-active compounds in pheromone gland extracts proved to be the corresponding alcohols to these aldehydes. In field-trapping experiments in Tawau, Malaysia, synthetic Z9–12 : Ald and Z9,11–12 : Ald at a 1 : 1 ratio, but not singly, attracted male S. nitens. Attractiveness of these two aldehydes could not be enhanced through the addition of their corresponding alcohols. Whether these differences in pheromone biology and chemistry between S. nitens and S. asigna are sufficient to prevent cross-attraction of heterospecific males or whether nonpheromonal mechanisms are required to maintain reproductive isolation is currently being studied.
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    The environmentalist 20 (2000), S. 257-271 
    ISSN: 1573-2991
    Keywords: evolution ; tides ; sea level ; time series
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The increasing use of computers since the 1960s, has implied the digitization of observations in meteorology, oceanography and other observational sciences. Enough data has been accumulated to suggest that some patterns of evolution in the world may be discernable. The present article deals with what appears as changing tides around Canada.
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  • 83
    ISSN: 1573-4943
    Keywords: Aluminum ; yeast hexokinase ; preferential interactions ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The aluminum and yeast hexokinase interaction was studied. Structural changes were correlated with variations in protein functionality. Results show two different behaviors: At low metal concentrations preferential adsorption of metal (and water exclusion) induces aggregate formation. No significant changes in the protein structure occur, but there is a continuous loss of activity (from the first concentration). At large salt concentrations a monomerization process and a conformational change in the secondary structure as well as in the three-dimensional structure take place. This change reduces the percentage of α-helix conformation, gives thermal stability to the protein, and allows the exposure of some tryptophan residue and hydrophobic regions. The protein inhibition increases. Conformational change and monomerization may allow access of the metal to the substrate site, mainly the ATP site. The inhibition in any case is of mixed type with a competitive component.
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  • 84
    ISSN: 1573-4927
    Keywords: ancient endogenous provirus ; evolution ; retrotransposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A new family of murine endogenous proviruses (VL6.0) is described here. The intact provirus is near 6 kb in length and shows a genomic organization of 5" LTR, gag, pol, env, and 3" LTR. The primer binding site (PBS) is that of a tRNAgly. The lack of functional open reading frames and occurrence of significant gaps in most, if not all, members of this group show it to be ancient. Our estimate of copy number per haploid genome is 30+. Members of this group have been isolated from Mus musculus domesticus, M. m. casteneus, M. m. hortulanus, M. caroli, and M. spretus. The occurrence of these sequences throughout such diverse members of the genus Mus may indicate that the date of the original infection predated the divergence of the extant Mus lineages at around 2.5 million years ago. Analysis of gap (deletion/insertion) patterns indicates that these sequences may have proliferated within the Mus genome by a mechanism of reverse transcriptase-mediated transposition. As yet, there are no closely related murine retroviruses described. The closest mammalian retrovirus based on sequence similarity is from the miniature swine (Sus scrofa).
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  • 85
    ISSN: 1573-4943
    Keywords: Creatine kinase ; human ; expression ; brain ; muscle ; purification ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We report the expression of the human muscle (CK-MM) and brain (CK-BB) creatine kinases in Escherichia coli. The proteins have been purified to apparent homogeneity and several of their physical and kinetic properties investigated. In the process, we have conclusively verified the correct DNA sequence of the genes encoding the respective isozymes, and determined the correct primary structure and mass of the gene products. Alignment of the primary sequences of these two enzymes shows 81% sequence identity with each other, and no obvious gross structural differences. However, Western blot analyses demonstrated the general lack of antigenic cross-reactivity between these isozymes. Preliminary kinetic analyses show the K m and k cat values for the creatine and MgATP substrates are similar to values reported for other isozymes from various tissues and organisms. The human muscle and brain CKs do not, however, exhibit the synergism of substrate binding that is observed, for example, in rabbit muscle creatine kinase.
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  • 86
    ISSN: 1432-2242
    Keywords: Key words Composite populations ; Triticum aestivum ; Blumeria (Erysiphe) graminis f. sp. tritici ; Selection ; Drift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Dynamic management has been proposed as a complementary strategy to gene banks for the conservation of genetic resources. The evolution of frequencies of genes for specific resistance towards powdery mildew (caused by Blumeria graminis f. sp. tritici) in populations of a French network for dynamic management of bread wheat genetic resources was investigated after 10 years of multiplication without human selection. The objective was to determine whether specific resistance gene diversity was maintained in the populations and whether any changes could be attributed to selection due to pathogen pressure. Seven populations, originating from four of the network sites, were characterized and compared to the initial population for six specific resistance gene frequencies detected by nine Blumeria graminis f. sp. tritici isolates. Diversity decreased at the population level, but because of a strong differentiation between the populations, this diversity was maintained at the network level. The comparison of Fst parameters estimated on neutral markers (RFLP) and on resistance gene data revealed that in two of the populations specific resistance genes had been selected by pathogen pressure, whereas evolution in two other populations seemed to be the result of genetic drift. For the three last populations, conclusions were less clear, as one had probably experienced a strong bottleneck and the other two presented intermediate Fst values. A dynamic management network with sites contrasted for pathogen pressure, allowing genetic drift in some populations and selection in others, appeared, at least on the short term, to be a good tool for maintaining the diversity of genes for specific resistance to powdery mildew.
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  • 87
    ISSN: 1432-0762
    Keywords: Key words Copulation duration ; Explosive mating system ; Ejaculate size ; Lepidoptera ; Mating history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The mating system of the Australian lycaenid butterfly, Jalmenus evagoras, is highly unusual compared to most other Lepidoptera. Characteristics of this system, which has been termed an ’explosive mating strategy,’ include the formation of an intensely competitive mating aggregation of males, a highly male biased operational sex ratio, a lack of discrimination and mate choice by both sexes, a high variance in male mating success, and female monogamy. In this study, we tested the hypothesis that multiple mating by males imposes physiological costs resulting in smaller spermatophores, and that this results in a fitness cost to females. We found that male J. evagoras transferred only 2.2% of their eclosion weight during their first mating, consistent with the hypothesis that males of monandrous species produce a relatively small investment. The wet weight of the ejaculate declined by an average of 27% at the second mating and the dry weight by 29%, and an intermating interval of 5–9 days was needed for the ejaculate to return to the size at the first mating, regardless of male size or age. Wet ejaculate mass increased proportionally with male size, though dry mass was proportionally larger in smaller males. Ejaculate mass tended to increase with male age at both first and second matings. Female characteristics, in general, did not affect ejaculate mass, although the wet weight of the ejaculate was positively associated with female weight at the second mating. Copulation duration increased from 2.4 h to approximately 3 h at the second mating, and to over 4 h at the third and fourth matings. Fecundity was positively correlated with female size but not with mating history, copulation duration, or any other characteristics measured for either males or females. Female longevity declined significantly as the number of times the male partner had previously mated increased. We conclude that despite the small male investment in ejaculate, the costs of multiple mating may nonetheless be significant, as indicated by the reduction in ejaculate mass, an increase in copulation duration, and reduction in female lifespan with increasing mating number.
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  • 88
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    Russian chemical bulletin 49 (2000), S. 1974-1976 
    ISSN: 1573-9171
    Keywords: ammonium dinitramide ; thermal decomposition ; kinetics ; stabilization ; isotope composition
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of accumulation of the main products of thermal decomposition of ammonium dinitramide in the melt was investigated. The isotope composition of nitrogen-containing gases evolved by the decomposition of 15NH4N(NO2)2 and NH4 15N(NO2)2 was found. Easily oxidized salts, amines, amides, iodides, and other compounds soluble in the melt interfere with the liquid-phase decomposition of ammonium dinitramide.
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  • 89
    ISSN: 1573-9171
    Keywords: 2-alkylthiopropenals ; Diels–Alder reaction ; kinetics ; reaction mechanism ; 2,5-dialkylthio-3,4-dihydro-2H-pyran-2-carbaldehyde ; IR spectroscopy ; ab initio calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of 2-alkylthiopropenals cyclodimerization was studied in the temperature range from -7 to +42 °C in heptane and at 20 °C in various solvents. The rate constants for cyclodimerization of 2-alkylthiopropenals are four orders of magnitude higher than those for dimerization of the oxygen-containing analogs, 2-alkoxypropenals, and are independent of the solvent polarity and substituent steric constant. The activation parameters for 2-butylthiopropenal cyclodimerization were estimated. The distribution of electron density in the 2-methoxy- and 2-methylthiopropenals molecules was calculated by the ab initio method. From comparison of the HOMO and LUMO energies for these aldehydes it was concluded that the ratio between the cyclodimerization rates for 2-alkylthio-, 2-ethoxypropenals, and propenal is determined by the HOMO–LUMO gap.
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  • 90
    ISSN: 1608-3245
    Keywords: DNA ; kinetics ; oligonucleotide derivatives ; photomodification ; sensitization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Quantitative characteristics of thermodynamic and kinetic cooperativity arising in the process of photomodification of a single-stranded DNA fragment with binary systems of oligonucleotide conjugates forming an active site on the target were studied. Oligonucleotides of the binary system were complementary to adjacent segments of the DNA target, and contained arylazide (X) and perylene (S) residues covalently attached to their terminal phosphates. Upon irradiation at the perylene absorption wavelength, the target was modified by the arylazide residue, which was activated owing to the contiguity with the sensitizing perylene group in the tandem complex. Basing on the kinetic data, the constants of association of both derivatives of oligonucleotides with the target were determined: K x = 1.13 · 106 M–1, K s = 1.49 · 104 M–1. It was determined that association of both oligonucleotides with the target proceeded with a positive cooperativity characterized by parameter α = 45. The kinetic cooperativity parameter β was found to be approximately equal to 200; this characterized the acceleration of target modification in complex with the binary reagent versus that in the absence of sensitizer.
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  • 91
    ISSN: 1618-2545
    Keywords: biogeography ; calmodulin ; DNA sequence ; elongation factor EF-1α ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phylogenetic relationships within theGibberella fujikuroi species complex were extended to newly discovered strains using nucleotide characters obtained by sequencing polymerase chain reaction (PCR) amplified DNA from 4 loci used in a previous study [nuclear large subunit 28S rDNA, nuclear ribosomal internal transcribed spacer (ITS) region, mitochondriaal small subunit (mtSSU) ribosomal DNA, and β-tubulin] together with two newly sampled protein-encoding nuclear genes, translation elongation factor EF-1α and calmodulin. Sequences from the ribosomal ITS region were analyzed separately and found to contain of two highly divergent, nonorthologous ITS2 types. Phylogenetic analysis of the individual and combined datasets identified 10 new phylogenetically distinct species distributed among the following three areas: 2 within Asia and 4 within both Africa and South America. Hypotheses of the monophyly ofFusarium subglutinans and its two formae speciales, f. sp.pini and f. sp.ananas, were strongly rejected by a likelihood analysis. Maximum parsimony results further indicate that the protein-encoding nuclear genes provide considerably more phylogenetic signal that the ribosomal genes sequenced. Relative apparent synapomorphy analysis was used to detect long-branch attraction taxa and to obtain a statistical measure of phylogenetic signal in the individual and combined datasets.
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  • 92
    ISSN: 1618-2545
    Keywords: Ascomycota ; evolution ; pyrenomycetes ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To investigate the systematic position of the unitunicate pyremomycetePapulosa amerospora, we performed phylogenetic analyses of SSU rDNA sequences from 37 ascomycetes. Among these sequences were some new ones from taxa that might be related toPapulosa: Hyponectriaceae (Hyponectria buxi, Monographella nivalis), Phyllachorales (Phyllachora graminis), and Xylariales (Barrmaelia melanotes, Poronia punctata). Our results showed 100% bootstrap support for a clade of all unitunicate pyrenomycetes, the class Sordariomycetes. We also found strong support for recognizing the subclasses Hypocreomycetidae and Xylariomycetidae. The remaining taxa, belonging to subclass Sordariomycetidae, appeared as a polyphyletic group in one analysis, but was monophyletic when shorter SSU sequences were used.Barrmaelia melanotes, Poronia punctata, Hyponectria buxi, andMonographella nivalis are members of Xylariomycetidae, but we could not determine whetherMonographella should be included in Hyponectriaceae. The new family Papulosaceae is erected forPapulosa on molecular and morphological bases, but the exact systematic position ofPapulosa within subclass Sordariomycetidae is still uncertain, since the genus did not cluster consistently with any of the included taxa. Phyllachorales are not closely related to Diaporthales, as previously suggested.
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  • 93
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    Russian journal of plant physiology 47 (2000), S. 734-739 
    ISSN: 1608-3407
    Keywords: Triticum aestivum ; bioelectric potentials ; frost resistance ; critical points
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Winter wheat (Triticum aestivum L.) seedlings of three cultivars differing in frost resistance were used to study cooling-induced changes in the bioelectric potential. Measurements were performed with nonfreezing graphite–glycerol electrodes in the regime of monitoring. Upon a gradual change in air temperature from 20 to –15°C at the rates of 20 and 2°C/h, the bioelectric potential underwent abrupt transitions at certain moments, indicating changes in the physiological condition of plants. The time required for the achievement of these critical states, as well as the survival of plants after thawing, depended both on the temperature and the cooling rate. Apparently, these characteristics were related to the dynamics of phase transitions of water. Cultivar-specific features were manifested in the different abilities of plants to maintain free water in a supercooled state. It is supposed that the critical points are related to the cold resistance of colloid systems and to the temperature lethal for plants.
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  • 94
    ISSN: 1608-3407
    Keywords: Dunaliella salina ; lactate dehydrogenase ; kinetics ; glycerol synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dependence of the catalytic properties of lactate dehydrogenase (LDH, EC 1.1.1.27) from a halophilic alga Dunaliella salina, a glycophilic alga Chlamydomonas reinhardtii, and from porcine muscle on glycerol concentration, medium pH, and temperature was investigated. Several chemical properties of the enzyme from D. salina differentiated it from the LDH preparation obtained from C. reinhardtii and any homologous enzymes of plant, animal, and bacterial origin. (1) V max of pyruvate reduction manifested low sensitivity to the major intracellular osmolyte, glycerol. (2) The affinity of LDH for its coenzyme NADH dropped in the physiological pH region of 6–8. Above pH 8, NADH virtually did not bind to LDH, while the enzyme affinity for pyruvate did not change considerably. (3) The enzyme thermostability was extremely low: LDH was completely inactivated at room temperature within 30 min. The optimum temperature for pyruvate reduction (32°C) was considerably lower than with the enzyme preparations from C. reinhardtii (52°C) and porcine muscle (61°C). (4) NADH greatly stabilized LDH: the ratio of LDH inactivation constants in the absence of the coenzyme and after NADH addition at the optimum temperature in the preparation from D. salina exceeded the corresponding indices of LDH preparations from C. reinhardtii twelve times and from porcine muscle eight times. The authors believe that these LDH properties match the specific metabolism of D. salina which is set at rapid glycerol synthesis under hyperosmotic stress conditions. The increase of cytoplasmic pH value produced in D. salina by the hyperosmotic shock can switch off the terminal reaction of the glycolytic pathway and thus provide for the most efficient utilization of NADH in the cycle of glycerol synthesis. As LDH is destabilized in the absence of NADH, this reaction is also switched off. In the course of alga adaptation to the hyperosmotic shock, glycerol accumulation and the neutralization of intracellular pH stabilize LDH, thus creating the conditions for restoring the complete glycolytic cycle.
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  • 95
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    Journal of applied phycology 12 (2000), S. 331-339 
    ISSN: 1573-5176
    Keywords: algal biomass ; algal uptake ; ammonia stripping ; biological nutrient removal ; high rate algal ponds ; nitrogen ; nutrients ; nitrification ; urban wastewater treatment ; waste stabilisation ponds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two experimental high rate algal ponds (HRAPs) (1.5m2, 570 L per unit), each with a secondaryclarifier for algal biomass separation (0.025 m2,without recirculation), were fed with urban wastewaterfor a one-year period (June 1993 to July 1994). TheHRAPs were installed on the roof of the Department ofHydraulic, Coastal and Environmental Engineering ofthe Technical University of Catalonia, Barcelona,Spain (lat. 41° 24′ 42″ N; long. 2° 7′42″ E). Nitrogen removal efficiency and changes intotal nitrogen, total organic nitrogen,NH4 +-N, and oxidized nitrogen underdifferent hydraulic retention times (HRTs) werecompared. HRAP A was always operated at a higherHRT than HRAP B. Both HRAPs were subjected to thesame environmental conditions of solar radiation, airtemperature and influent water quality. Grab samplesof influent, effluent of the HRAP (mixed liquor) andfinal effluent from the clarifiers were taken once aweek. The annual average nitrogen removal was 73% forHRAP A, and 57% for HRAP B. Higher removal in HRAP Awas due to a lower inorganic nitrogen concentration inits effluent. Significant differences (p〉 0.05) inthe relative proportions of nitrogen forms between thetwo HRAPs were observed only in autumn and winter.This was mainly because HRAP B did not achieve a highlevel of NH4 +-N removal by stripping andalgal uptake, as observed in HRAP A. NH4 +-Nstripping was the most important mechanism fornitrogen removal (mean efficiency of 47% and 32% inHRAP A and B, respectively) followed by algal uptake,and subsequent algal separation in the clarifiers(mean efficiency of 26% and 25% in HRAP A and Brespectively). The conclusion of this study is thatHRT determines both the nitrogen removal efficiencyand the distribution of nitrogen forms in the effluentof a HRAP. The nitrogen removal level can becontrolled through suitable HRT operating strategies.By operating at a HRT of 4 days in spring and summer,and 10 days in autumn and winter, nitrogenconcentration in the effluent of a HRAP system can bereduced to less than 15 mg L-1 N.
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  • 96
    ISSN: 1573-4986
    Keywords: β-glycosidase ; temperature dependence ; kinetics ; glucose ; transglycosylation ; (Thermus thermophilus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A β-glycosidase of a thermophile, Thermus thermophilus, belonging to the glycoside hydrolase family 1, was cloned and overexpressed in Escherichia coli. The purified enzyme (Ttβgly) has a broad substrate specificity towards β-D-glucoside, β-D-galactoside and β-D-fucoside derivatives. The thermostability of Ttβgly was exploited to study its kinetic properties within the range 25–80[emsp4 ]°C. Whatever the temperature, except around 60[emsp4 ]°C, the enzyme displayed non-Michaelian kinetic behavior. Ttβgly was inhibited by high concentrations of substrate below 60[emsp4 ]°C and was activated by high concentrations of substrate above 60[emsp4 ]°C. The apparent kinetic parameters (k cat and K m ) were calculated at different temperatures. Both k cat and K m increased with an increase in temperature, but up to 75[emsp4 ]°C the values of k cat increased much more rapidly than the values of K m . The observed kinetics might be due to a combination of factors including inhibition by excess substrate and stimulation due to transglycosylation reactions. Our results show that the substrate could act not only as a glycosyl donor but also as a glycosyl acceptor. In addition, when the glucose was added to reaction mixtures, inhibition or activation was observed depending on both substrate concentration and temperature. A reaction model is proposed to explain the kinetic behavior of Ttβgly. The scheme integrates the inhibition observed at high concentrations of substrate and the activation due to transglycosylation reactions implicating the existence of a transfer subsite.
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  • 97
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    Glycoconjugate journal 17 (2000), S. 465-483 
    ISSN: 1573-4986
    Keywords: N-acetylglucosaminyltransferases ; glycosylation ; glycoproteins ; Golgi complex ; evolution ; development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This review covers discoveries made over the past 30–35 years that were important to our understanding of the synthetic pathway required for initiation of the antennae or branches on complex N-glycans and O-glycans. The review deals primarily with the author's contributions but the relevant work of other laboratories is also discussed. The focus of the review is almost entirely on the glycosyltransferases involved in the process. The following topics are discussed. (1) The localization of the synthesis of complex N-glycan antennae to the Golgi apparatus. (2) The “evolutionary boundary” at the stage in N-glycan processing where there is a change from oligomannose to complex N-glycans; this switch correlates with the appearance of multicellular organisms. (3) The discovery of the three enzymes which play a key role in this switch, N-acetylglucosaminyltransferases I and II and mannosidase II. (4) The “yellow brick road” which leads from oligomannose to highly branched complex N-glycans with emphasis on the enzymes involved in the process and the factors which control the routes of synthesis. (5) A short discussion of the characteristics of the enzymes involved and of the genes that encode them. (6) The role of complex N-glycans in mammalian and Caenorhabditis elegans development. (7) The crystal structure of N-acetylglucosaminyltransferase I. (8) The discovery of the enzymes which synthesize O-glycan cores 1, 2, 3 and 4 and their elongation.
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  • 98
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    Journal of bioeconomics 2 (2000), S. 9-23 
    ISSN: 1573-6989
    Keywords: evolution ; altruism ; morality ; utilitarianism ; Marxism ; Rawls ; fairness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Economics
    Notes: Abstract Several evolutionary mechanisms have been identified in the literature that would generate altruism in humans. The most powerful (except for kin selection) and most controversial is group selection, as recently analyzed by Sober & D.S. Wilson. I do not take a stand on the issue of the existence of group selection. Instead, I examine the level of human altruism that could exist if group selection were an engine of human evolution. For the Sober & Wilson mechanism to work, groups practicing altruism must grow faster than other groups. I call altruistic behavior that would lead to faster growth ‘efficient altruism’. This often consists of cooperation in a prisoner's dilemma. ltruistic acts such as helping a temporarily hungry or injured person would qualify as efficient altruism. Efficient altruism would also require monitoring recipients to avoid shirking. Utilitarianism would be an ethical system consistent with efficient altruism, but Marxism or the Rawlsian system would not. Discussions of efficient altruism also help understand intuitions about fairness. We perceive those behaviors as ‘fair’ that are consistent with efficient altruism. It is important to understand that, even if humans are selected to be altruistic, the forms of altruism that might exist must be carefully considered and ircumscribed.
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  • 99
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    Biology and philosophy 15 (2000), S. 443-463 
    ISSN: 1572-8404
    Keywords: David Hull ; evolution ; selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract One of the principal difficulties in assessing Science as aProcess (Hull 1988) is determining the relationship between the various elements of Hull's theory. In particular, it is hard to understand precisely how conceptual selection is related to Hull's account of the social dynamics of science. This essay aims to clarify the relation between these aspects of his theory by examining his discussion of the``demic structure'' of science. I conclude that the social account cando significant explanatory work independently of the selectionistaccount. Further, I maintain that Hull's treatment of the demicstructure of science points us toward an important set of issues insocial epistemology. If my reading of Science as a Process iscorrect, then most of Hull's critics (e.g., those who focus solelyon his account of conceptual selection) have ignored promisingaspects of his theory.
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  • 100
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    Biology and philosophy 15 (2000), S. 493-508 
    ISSN: 1572-8404
    Keywords: complexity ; entropy balance ; environment independence ; evolution ; information fundamental identity ; uncertainty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Some real objects show a very particular tendency: that of becomingindependent with regard to the uncertainty of their surroundings. This isachieved by the exchange of three quantities: matter, energy andinformation. A conceptual framework, based on both Non-equilibriumThermodynamic and the Mathematical Theory of Communication is proposedin order to review the concept of change in living individuals. Three mainsituations are discussed in this context: passive independence inconnection with resistant living forms (such as seeds, spores, hibernation,...), active independence in connection with the life span of aliving individual (whether an ant or an ant farm), and the newindependence in connection with the general debate of biological evolution.
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