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CRAWFORD DOUGLAS L.; PIERCE VALERIE A.; SEGAL JEFF A. 《Integrative and comparative biology》1999,39(2):389-400
Comparative biochemistry and physiology offer the advantageof specifically defining the functional parameters or traitsthat affect an organism's performance (e.g., amino acids thataffect Km, enzymes that affect metabolism). By combining thesefunctional determinations with both intraspecific and phylogeneticallyappropriate analyses, comparative biologists can indicate thata trait is biologically important by demonstrating that it isevolving by natural selection. An evolutionary approach maybenefit from the analysis of variation within and among closelyrelated species. The advantages of analyzing closely relatedspecies are that they allow one to identify more definitivelythe derived conditions and suggest why differences arose. Importantly,there is substantial variation in physiological and biochemicaltraits within and among closely related species. For example,among species within a single genus of teleost, Fundulus, thevariation in enzyme expression is similar to the variation seenamong most superorders of teleost. However, most of the variationwithin the genus Fundulus is most readily explained by evolutionarydistance, and thus there is no compelling reason for furtheradaptive hypotheses. Extending this observation, the greaterthe phylogenetic distance between taxa in a comparative study,the more likely there will be a statistically significant differencethat may only represent evolutionary time. The molecular mechanismsaffecting adaptive variation in enzyme expression appear tobe readily altered and may vary within a species or betweenacclimation conditions. Thus, studies among closely relatedorganisms are more likely to identify the specific molecularor biochemical changes responsible for adaptive variation. 相似文献
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Yuansha Chen Peter Bystricky Jacob Adeyeye Pinaki Panigrahi Afsar Ali Judith A Johnson CA Bush JG MorrisJr OC Stine 《BMC microbiology》2007,7(1):20
Background
In V. cholerae, the biogenesis of capsule polysaccharide is poorly understood. The elucidation of capsule structure and biogenesis is critical to understanding the evolution of surface polysaccharide and the internal relationship between the capsule and LPS in this species. V. cholerae serogroup O31 NRT36S, a human pathogen that produces a heat-stable enterotoxin (NAG-ST), is encapsulated. Here, we report the covalent structure and studies of the biogenesis of the capsule in V. cholerae NRT36S. 相似文献73.
Andrew JG Simpson 《Genome biology》2000,1(1):reports411.1-reports4112
A meeting report of the sessions on human, eukaryotic and bacterial genome sequencing at the American Society for Microbiology and Institut Pasteur joint conference: Genomes 2000 International Conference on Microbial and Model Genomes, Paris, April 11-15, 2000 相似文献
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ERIC BURNHAM LOUIS C. BENDER GARY A. EICEMAN KARISA M. PIERCE SATENDRA PRASAD 《The Journal of wildlife management》2008,72(3):792-797
Abstract: Identification of wildlife species from indirect evidence can be an important part of wildlife management, and conventional methods can be expensive or have high error rates. We used chemical characterization of the volatile organic constituents (VOCs) in scat as a method to identify 5 species of North American canids from multiple individuals. We sampled vapors of scats in the headspace over a sample using solid-phase microextraction and determined VOC content using gas chromatography with a flame ionization detector. We used linear discriminant analysis to develop models for differentiating species with bootstrapping to estimate accuracy. Our method correctly classified 82.4% (bootstrapped 95% CI = 68.8–93.8%) of scat samples. Red fox (Vulpes vulpes) scat was most frequently misclassified (25.0% of scats misclassified); red fox was also the most common destination for misclassified samples. Our findings are the first reported identification of animal species using VOCs in vapor emissions from scat and suggest that identification of wildlife species may be plausible through chemical characterization of vapor emissions of scat. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):792–797; 2008) 相似文献
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Experiments are reviewed that indicate embryonic fields arecapable of regulating the neoplastic attributes of their closelyrelated carcinomas. In the case of blastocyst regulation ofembryonal carcinoma cells the reaction is mediated by contactof the cancer cells with trophectodermal cells in the presenceof blastocele fluid. In the case of regulation of melanoma,the reaction is mediated in the embryonic skin at the time normalmelanocytes migrate into it. A diffusible factor that inhibitscell division and seems to affect differentiation is involved.In the case of neuroblastoma, a degree of regulation is demonstrablein the neural crest migratory pathway, but the maximal effectis found in the adrenal, renal, and testicular primordia. Afactor inhibitory of mitosis for adenocarcinoma of the breastcan be demonstrated in the breast primordium. It is concludedthat there must be an embryonic field capable of regulatingevery kind of carcinoma: understanding of the phenomena maylead to a noncytotoxic cure for carcinoma, and through the useof cancer cells as probes of embryonic development to an understandingof embryonic induction. 相似文献
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