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排序方式: 共有868条查询结果,搜索用时 218 毫秒
861.
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René E. van Dijk Corine M. Eising Richard M. Merrill Filiz Karadas Ben Hatchwell Claire N. Spottiswoode 《Oecologia》2013,171(2):379-389
Maternal effects can influence offspring phenotype with short- and long-term consequences. Yet, how the social environment may influence egg composition is not well understood. Here, we investigate how laying order and social environment predict maternal effects in the sociable weaver, Philetairus socius, a species that lives in massive communal nests which may be occupied by only a few to 100+ individuals in a single nest. This range of social environments is associated with variation in a number of phenotypic and life-history traits. We investigate whether maternal effects are adjusted accordingly. We found no evidence for the prediction that females might benefit from modifying brood hierarchies through an increased deposition of androgens with laying order. Instead, females appear to exacerbate brood reduction by decreasing the costly production of yolk mass and antioxidants with laying order. Additionally, we found that this effect did not depend on colony size. Finally, in accordance with an expected increased intensity of environmental stress with increasing colony size, we found that yolk androgen concentration increased with colony size. This result suggests that females may enhance the competitive ability of offspring raised in larger colonies, possibly preparing the offspring for a competitive social environment. 相似文献
864.
Background
A logical model of the known metabolic processes in S. cerevisiae was constructed from iFF708, an existing Flux Balance Analysis (FBA) model, and augmented with information from the KEGG online pathway database. The use of predicate logic as the knowledge representation for modelling enables an explicit representation of the structure of the metabolic network, and enables logical inference techniques to be used for model identification/improvement. 相似文献865.
866.
Merrill S. Babcock Maria R. Marino William T. Gunning III Gary D. Stoner 《In vitro cellular & developmental biology. Plant》1983,19(5):403-415
Summary The clonal growth and serial propagation of rat esophageal epithelial cells in low serum-containing medium has been achieved
without feeder layers or conditioned medium. To date, a total of four lines have been developed and maintained for as many
as 40 passages in culture. Growth of the cells was possible only after modifying the culture medium (PFMR-4) by reducing the
calcium concentration from 1 to 0.1 mM, and by adding low levels of dialyzed fetal bovine serum and seven growth factors; i.e. epidermal growth factor, hydrocortisone,
ethanolamine, phosphoethanolamine, insulin, transferrin, and cholera toxin. Cell lines have been developed from both explant
outgrowths and enzyme dissociated esophagi. The epithelial nature of the cells was confirmed by electron microscopy and immunological
methods. Clonal growth studies revealed that optimal cell growth occurred in medium containing 2.4% dialyzed fetal bovine
serum and 0.1 mM calcium. Calcium levels of 0.3 mM or higher caused the cells to stratify and undergo terminal differentiation. Coating the culture dishes with collagen, or
a combination of collagen, fibronectin, and bovine serum albumin, increased both the cell growth rate and the colony forming
efficiency. The successful long term culture of rat esophageal epithelial cells permits their use as models in studies concerned
with esophageal differentiation and carcinogenesis.
This investigation was supported by U.S. Public Health Service Grant CA 28950, awarded by the National Cancer Institute, Bethesda,
MD. 相似文献
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