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排序方式: 共有367条查询结果,搜索用时 15 毫秒
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J J Skehel M D Waterfield J W McCauley K Elder D C Wiley 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1980,288(1029):335-339
The biosynthesis of the haemagglutinin glycoproteins of infectious influenza virus particles involves proteolytic cleavage of the primary translation products and the amino acid sequences at the two sites of processing are presented. In addition, details of the primary structure of the haemagglutinin of A/Japan/305/57 (H2N1) are reported and compared with information available for haemagglutinins of other subtypes. 相似文献
3.
Vectorially oriented membrane protein monolayers: profile structures via x-ray interferometry/holography. 总被引:2,自引:2,他引:0
J A Chupa J P McCauley Jr R M Strongin A B Smith rd J K Blasie L J Peticolas J C Bean 《Biophysical journal》1994,67(1):336-348
X-ray interferometry/holography was applied to meridional x-ray diffraction data to determine uniquely the profile structures of a single monolayer of an integral membrane protein and a peripheral membrane protein, each tethered to the surface of a solid inorganic substrate. Bifunctional, organic self-assembled monolayers (SAMs) were utilized to tether the proteins to the surface of Ge/Si multilayer substrates, fabricated by molecular beam epitaxy, to facilitate the interferometric/holographic x-ray structure determination. The peripheral membrane protein yeast cytochrome c was covalently tethered to the surface of a sulfhydryl-terminated 11-siloxyundecanethiol SAM via a disulfide linkage with residue 102. The detergent-solubilized, photosynthetic reaction center integral membrane protein was electrostatically tethered to the surface of an analogous amine-terminated SAM. Optical absorption measurements performed on these two tethered protein monolayer systems were consistent with the x-ray diffraction results indicating the reversible formation of densely packed single monolayers of each fully functional membrane protein on the surface of the respective SAM. The importance of utilizing the organic self-assembled monolayers (as opposed to Langmuir-Blodgett) lies in their ability to tether specifically both soluble peripheral membrane proteins and detergent-solubilized integral membrane proteins. The vectorial orientations of the cytochrome c and the reaction center molecules were readily distinguishable in the profile structure of each monolayer at a spatial resolution of 7 A. 相似文献
4.
David E. McCauley 《Evolution; international journal of organic evolution》1991,45(7):1675-1684
The patchy local distribution of the common milkweed, Asclepias syriaca, organizes populations of a beetle that feeds on it, Tetraopes tetraophthalmus, into numerous local demes. Genetic and ecological characteristics of demes of adult milkweed beetles occupying two naturally occurring size classes of patches, defined as large and small, were studied in order to describe the effect of patch size variation on local population structure. Allele frequency variance in two of three protein polymorphisms was significantly greater in collections of beetles from an array of 13 small patches when compared to collections from an array of 11 large populations. A multivariate measure of variance using information from all 3 genetic markers confirmed that the small patches displayed greater overall genetic differentiation. This was further quantified by computing an Fst value, combined across loci, of 0.018 for the small patches and 0.004 for the large patches. No significant difference between patch size classes in mean allele frequency was detected. Mark and recapture studies of the adults found in five small and four large patches showed the residence times of adults in small patches to be less than half of those found in large patches. This was interpreted as resulting from higher emigration rates from small patches. It is proposed that greater genetic differentiation is found among demes from smaller patches because smaller patches support smaller population sizes and further because smaller patches act as net exporters of migrants while larger patches act as net migrant importers. 相似文献
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Mark McCauley Donovan P. German Nathan K. Lujan Colin R. Jackson 《Ecology and evolution》2020,10(14):7117-7128
Neotropical wood‐eating catfishes (family Loricariidae) can occur in diverse assemblages with multiple genera and species feeding on the same woody detritus. As such, they present an intriguing system in which to examine the influence of host species identity on the vertebrate gut microbiome as well as to determine the potential role of gut bacteria in wood digestion. We characterized the gut microbiome of two co‐occurring catfish genera and four species: Panaqolus albomaculatus, Panaqolus gnomus, Panaqolus nocturnus, and Panaque bathyphilus, as well as that of submerged wood on which they feed. The gut bacterial community did not significantly vary across three gut regions (proximal, mid, distal) for any catfish species, although interspecific variation in the gut microbiome was significant, with magnitude of interspecific difference generally reflecting host phylogenetic proximity. Further, the gut microbiome of each species was significantly different to that present on the submerged wood. Inferring the genomic potential of the gut microbiome revealed that the majority of wood digesting pathways were at best equivalent to and more often depleted or nonexistent within the catfish gut compared to the submerged wood, suggesting a minimal role for the gut microbiome in wood digestion. Rather, these fishes are more likely reliant on fiber degradation performed by microbes in the environment, with their gut microbiome determined more by host identity and phylogenetic history. 相似文献
8.
Andrés Moreno-Estrada Simon Gravel Fouad Zakharia Jacob L. McCauley Jake K. Byrnes Christopher R. Gignoux Patricia A. Ortiz-Tello Ricardo J. Martínez Dale J. Hedges Richard W. Morris Celeste Eng Karla Sandoval Suehelay Acevedo-Acevedo Paul J. Norman Zulay Layrisse Peter Parham Juan Carlos Martínez-Cruzado Esteban González Burchard Michael L. Cuccaro Eden R. Martin Carlos D. Bustamante 《PLoS genetics》2013,9(11)
The Caribbean basin is home to some of the most complex interactions in recent history among previously diverged human populations. Here, we investigate the population genetic history of this region by characterizing patterns of genome-wide variation among 330 individuals from three of the Greater Antilles (Cuba, Puerto Rico, Hispaniola), two mainland (Honduras, Colombia), and three Native South American (Yukpa, Bari, and Warao) populations. We combine these data with a unique database of genomic variation in over 3,000 individuals from diverse European, African, and Native American populations. We use local ancestry inference and tract length distributions to test different demographic scenarios for the pre- and post-colonial history of the region. We develop a novel ancestry-specific PCA (ASPCA) method to reconstruct the sub-continental origin of Native American, European, and African haplotypes from admixed genomes. We find that the most likely source of the indigenous ancestry in Caribbean islanders is a Native South American component shared among inland Amazonian tribes, Central America, and the Yucatan peninsula, suggesting extensive gene flow across the Caribbean in pre-Columbian times. We find evidence of two pulses of African migration. The first pulse—which today is reflected by shorter, older ancestry tracts—consists of a genetic component more similar to coastal West African regions involved in early stages of the trans-Atlantic slave trade. The second pulse—reflected by longer, younger tracts—is more similar to present-day West-Central African populations, supporting historical records of later transatlantic deportation. Surprisingly, we also identify a Latino-specific European component that has significantly diverged from its parental Iberian source populations, presumably as a result of small European founder population size. We demonstrate that the ancestral components in admixed genomes can be traced back to distinct sub-continental source populations with far greater resolution than previously thought, even when limited pre-Columbian Caribbean haplotypes have survived. 相似文献
9.
Celina B. Baines Justin M. J. Travis Shannon J. McCauley Greta Bocedi 《Evolution; international journal of organic evolution》2020,74(10):2238-2249
Empirical studies have documented both positive and negative density-dependent dispersal, yet most theoretical models predict positive density dependence as a mechanism to avoid competition. Several hypotheses have been proposed to explain the occurrence of negative density-dependent dispersal, but few of these have been formally modeled. Here, we developed an individual-based model of the evolution of density-dependent dispersal. This model is novel in that it considers the effects of density on dispersal directly, and indirectly through effects on individual condition. Body condition is determined mechanistically, by having juveniles compete for resources in their natal patch. We found that the evolved dispersal strategy was a steep, increasing function of both density and condition. Interestingly, although populations evolved a positive density-dependent dispersal strategy, the simulated metapopulations exhibited negative density-dependent dispersal. This occurred because of the negative relationship between density and body condition: high density sites produced low-condition individuals that lacked the resources required for dispersal. Our model, therefore, generates the novel hypothesis that observed negative density-dependent dispersal can occur when high density limits the ability of organisms to disperse. We suggest that future studies consider how phenotype is linked to the environment when investigating the evolution of dispersal. 相似文献
10.
Divakaran Murugesapillai Micah J. McCauley Ran Huo Molly H. Nelson Holte L. James Maher III Nathan E. Israeloff 《Journal of biomolecular structure & dynamics》2013,31(1)
HMO1 proteins are abundant Saccharomyces cerevisiae (yeast) High Mobility Group Box (HMGB) protein (Kamau, Bauerla & Grove, 2004). HMGB proteins are nuclear proteins which are known to be architectural proteins (Travers, 2003). HMO1 possesses two HMGB box domains. It has been reported that double box HMGB proteins induce strong bends upon binding to DNA. It is also believed that they play an essential role in reorganizing chromatin and, therefore, are likely to be involved in gene activation. To characterize DNA binding we combine single molecule stretching experiments and AFM imaging of HMO1 proteins bound to DNA. By stretching DNA bound to HMO1, we determine the dissociation constant, measure protein induced average DNA bending angles, and determine the rate at which torsional constraint of the DNA is released by the protein. To further investigate the local nature of the binding, AFM images of HMO1-DNA complexes are imaged, and we probe the behavior of these complexes as a function of protein concentration. The results show that at lower concentrations, HMO1 preferentially binds to the ends of the double helix and links to the separate DNA strands. At higher concentrations HMO1 induces formation of a complex network that reorganizes DNA. Although HMG nuclear proteins are under intense investigation, little is known about HMO1. Our studies suggest that HMO1 proteins may facilitate interactions between multiple DNA molecules. 相似文献