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141.
Richard O. Prum 《Evolution; international journal of organic evolution》1994,48(5):1657-1675
Phylogenetic analyses of lekking, lek spatial organization, and cooperative and coordinated lek display in the manakins (Aves: Pipridae) demonstrate that variation in social behavior in the group has a strong, phylogenetic component. Two of the three classes of social behavior examined also show significant phylogenetic constraints. Current adaptive plasticity models are insufficient to explain the phylogenetic variation in these behaviors in the manakins. These findings support the conclusion that vertebrate reproductive social behavior has an evolutionary history, and that it is not determined solely by adaptive individual plasticity to current conditions. The evolution of social behavior, particularly through sexual selection, can have historical consequences that can limit subsequent behavioral adaptation. 相似文献
142.
143.
Anne M. Berry Eric M. Glare David Hansman James C. Paton 《FEMS microbiology letters》1989,65(3):275-278
Twenty-four of 63 enteric Gram-negative organisms (38.1%) which were isolated from 35 apparently healthy Nigerian students were found to have low trimethoprim resistance (MIC less than 1000 mg/l). These isolates were also found to be resistant to several other antibiotics and trimethoprim resistance was found to be transferable from 15 (62.5%) of the trimethoprim resistant organisms into E. coli EC 1005. It is likely that the high percentage of trimethoprim resistance encountered in this study is related to the high rate of resistance transfer which was observed. 相似文献
144.
145.
Incubation of [14C] caffeine with hepatic microsomes from male AKR/J mice resulted in the formation of several metabolites including 1, 3, 7-trimethylurate and 6-amino-5-(N-formylmethyl-amino)-1, 3-dimethyluracil. These two compounds comprised about 60% of products and are major urinary metabolites in several animals. When cytosol was included during incubation, there was a 14-fold increase in yield of the uracil at the expense of the urate; the combination of the two metabolites remained about 60% of total products. Cytosol alone was catalytically inert. Glutathione and other sulfhydryl compounds reproduced the effect of cytosol, and the action of cytosol was accounted for quantitatively by its sulfhydryl content. We propose that an oxidized intermediate of caffeine en route to trimethylurate is reduced by glutathione to the ring-opened uracil derivative. 相似文献
146.
147.
Mutations in Aprataxin cause the neurodegenerative syndrome ataxia oculomotor apraxia type 1. Aprataxin catalyzes removal of adenosine monophosphate (AMP) from the 5′ end of a DNA strand, which results from an aborted attempt to ligate a strand break containing a damaged end. To gain insight into which DNA lesions are substrates for Aprataxin action in vivo, we deleted the Saccharomyces cerevisiae HNT3 gene, which encodes the Aprataxin homolog, in combination with known DNA repair genes. While hnt3Δ single mutants were not sensitive to DNA damaging agents, loss of HNT3 caused synergistic sensitivity to H2O2 in backgrounds that accumulate strand breaks with blocked termini, including apn1Δ apn2Δ tpp1Δ and ntg1Δ ntg2Δ ogg1Δ. Loss of HNT3 in rad27Δ cells, which are deficient in long-patch base excision repair (LP-BER), resulted in synergistic sensitivity to H2O2 and MMS, indicating that Hnt3 and LP-BER provide parallel pathways for processing 5′ AMPs. Loss of HNT3 also increased the sister chromatid exchange frequency. Surprisingly, HNT3 deletion partially rescued H2O2 sensitivity in recombination-deficient rad51Δ and rad52Δ cells, suggesting that Hnt3 promotes formation of a repair intermediate that is resolved by recombination. 相似文献
148.
Chromosome numbers were determined for 86 Anthurium species. Fifty-one of these were newly determined with counts ranging from 2n = 24 to 66 and 30 being the most common. All known Anthurium chromosome numbers were summarized, and 43 taxonomic changes were made in the previous reports to reflect current taxonomy. In terms of somatic chromosome numbers, the numbers form four polyploid series of 20–40–60, 24–30–48–84, 28–56 and 30–60–90–ca. 124. Paleoaneuploidy, polyploidy and B-chromosomes are basic features of the genus, but subsequent recent aneuploidy is not. The exact nature of chromosome evolution in Anthurium remains to be elucidated. 相似文献
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150.
Bart A. Nolet Abel Gyimesi Roderick R. D. van Krimpen Willem F. de Boer Richard A. Stillman 《PloS one》2016,11(2)
Predicting the environmental impact of a proposed development is notoriously difficult, especially when future conditions fall outside the current range of conditions. Individual-based approaches have been developed and applied to predict the impact of environmental changes on wintering and staging coastal bird populations. How many birds make use of staging sites is mostly determined by food availability and accessibility, which in the case of many waterbirds in turn is affected by water level. Many water systems are regulated and water levels are maintained at target levels, set by management authorities. We used an individual-based modelling framework (MORPH) to analyse how different target water levels affect the number of migratory Bewick’s swans Cygnus columbianus bewickii staging at a shallow freshwater lake (Lauwersmeer, the Netherlands) in autumn. As an emerging property of the model, we found strong non-linear responses of swan usage to changes in water level, with a sudden drop in peak numbers as well as bird-days with a 0.20 m rise above the current target water level. Such strong non-linear responses are probably common and should be taken into account in environmental impact assessments. 相似文献