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131.
Migration (seasonal round-trip movement across relatively large distances) is common within the animal kingdom. This behaviour often incurs extreme costs in terms of time, energy, and/or survival. Climate, food, predation, and breeding are typically suggested as factors favouring the evolution of migration. Although disease regulation has also been considered, few studies consider it as the primary selective pressure for migration. Our aim was to determine, theoretically, under what conditions migration could reduce the long-term disease prevalence within a population, assuming the only benefits of migration are infection-related. We created two mathematical models, one where the population migrates annually and one where the entire population remains on the breeding ground year-round. In each we simulated disease transmission (frequency-dependent and density-dependent) and quantified eventual disease prevalence. In the migration model we varied the time spent migrating, disease-related migration mortality, and the overall migration mortality. When we compared results from the two models, we found that migration generally lowered disease prevalence. We found a population was healthier if it: (1) spent more time migrating (assuming no disease transmission during migration), (2) had higher disease-induced migration mortality, and (3) had an overall higher mortality when migrating (compared to not migrating). These results provide support for two previously proposed mechanisms by which migration can reduce disease prevalence (migratory escape and migratory cull), and also demonstrate that non-selective mortality during migration is a third mechanism. Our findings indicate that migration may be evolutionarily advantageous even if the only migratory benefit is disease control.  相似文献   
132.
Shu Li  Lin Tang  Hongna Bi 《Luminescence》2016,31(2):442-452
The aim of this study is to evaluate the binding behavior between pelargonidin‐3‐O‐glucoside (P3G) and bovine serum albumin (BSA) using multi‐spectroscopic, transmission electron microscopy (TEM) and molecular docking methods under physiological conditions. Fluorescence spectroscopy and time‐resolved fluorescence showed that the fluorescence of BSA could be quenched remarkably by P3G via a static quenching mechanism, and there is a single class of binding site on BSA. In addition, the thermodynamic functions ΔH and ΔS were –21.69 kJ/mol and 24.46 J/mol/K, indicating that an electrostatic interaction was a main acting force. The distance between BSA and P3G was 2.74 nm according to Förster's theory, illustrating that energy transfer occurred. In addition, the secondary structure of BSA changed with a decrease in the α‐helix content from 66.2% to 64.0% as seen using synchronous fluorescence, UV/vis, circular dichroism and Fourier transform infrared spectroscopies, whereas TEM images showed that P3G led to BSA aggregation and fibrillation. Furthermore, site marker competitive experiments and molecular docking indicated that P3G could bind with subdomain IIA of BSA. The calculated results of the equilibrium fraction showed that the concentration of free P3G in plasma was high enough to be stored and transported from the circulatory system to its target sites to provide therapeutic effects. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
133.
Homomorphic self‐incompatibility is a well‐studied example of a physiological process that is thought to increase population diversity and reduce the expression of inbreeding depression. Whereas theoretical models predict the presence of a large number of S‐haplotypes with equal frequencies at equilibrium, unequal allele frequencies have been repeatedly reported and attributed to sampling effects, population structure, demographic perturbation, sheltered deleterious mutations or selection pressure on linked genes. However, it is unclear to what extent unequal segregations are the results of gametophytic or sexual selection. Although these two forces are difficult to disentangle, testing S‐alleles in the offspring of controlled crosses provides an opportunity to separate these two phenomena. In this work, segregation and transmission of S‐alleles have been characterized in progenies of mixed donors and fully compatible pollinations under field conditions in Prunus avium. Seed set patterns and pollen performance have also been characterized. The results reveal paternal‐specific distorted transmission of S‐alleles in most of the crosses. Interestingly, S‐allele segregation within any given paternal or maternal S‐locus was random. Observations on pollen germination, pollen tube growth rate, pollen tube cohort size, seed set dynamics and transmission patterns strongly suggest post‐pollination, prezygotic sexual selection, with male–male competition as the most likely mechanism. According to these results, post‐pollination sexual selection takes precedence over frequency‐dependent selection in explaining unequal S‐haplotype frequencies.  相似文献   
134.
We developed nonintegrated methods to reprogram mouse embryonic fibroblast (MEF) cells into induced pluripotent stem cells (iPSCs) using pig pOct4, pSox2, and pc-Myc as well as human hKLF4, hAID, and hTDG that were carried by plasmid vectors. The 4F method employed pOct4, pSox2, pc-Myc, and hKLF4 to derive iPSC clones with naive embryonic stem cell (ESC)-like morphology. These 4F clones expressed endogenous mouse Nanog protein and could generate chimeras. In addition to the four conventional reprogramming factors used in the 4F method, hAID and hTDG were utilized in a 6F method to increase the conversion efficiency of reprogramming by approximately five-fold. One of the 6F plasmid derived iPSC (piPSC) clones was shown to be germline transmission competent.  相似文献   
135.
Direct exposure to stimuli in their environment is not the only way that animals learn about important information. Individuals can infer fear from a social context through observation. Like humans, rats are very social animals, and may learn to infer information about their environment through their interactions with conspecifics. Here, we first review different models for social transmission of information in rodents. Second, we examine different modes of communication that are important to social learning. Then, we cover the different proximate factors that are thought to modulate the social transmission of information. Next, we identify social and environmental conditions that impact social learning, and finally, we conclude by revisiting social transmission through the lens of the Tinbergen framework.  相似文献   
136.
The reduced costs of DNA sequencing and the use of such data for HIV‐1 clinical management and phylogenetic analysis have led to a massive increase of HIV‐1 sequences in the last few years. Phylogenetic analysis has shed light on the origin, spread and characteristics of HIV‐1 epidemics and outbreaks. Phylogenetic analysis is now also being used to advance our knowledge of the drivers of HIV‐1 transmission in order to design effective interventions. However, HIV phylogenetic analysis presents unique ethical challenges, which have not been fully explored. This review presents an analysis of what appear to be key ethical issues in HIV phylogenetics in the hope of stimulating further conceptual and empirical work in this rapidly emerging area. We structure the review using the Emanuel Framework, a systematic, holistic framework, which has been adapted for use in developing countries, which bear the brunt of the HIV‐1 pandemic.  相似文献   
137.
Microbiota play a central role in the functioning of multicellular life, yet understanding their inheritance during host evolutionary history remains an important challenge. Symbiotic microorganisms are either acquired from the environment during the life of the host (i.e. environmental acquisition), transmitted across generations with a faithful association with their hosts (i.e. strict vertical transmission), or transmitted with occasional host switches (i.e. vertical transmission with horizontal switches). These different modes of inheritance affect microbes’ diversification, which at the two extremes can be independent from that of their associated host or follow host diversification. The few existing quantitative tools for investigating the inheritance of symbiotic organisms rely on cophylogenetic approaches, which require knowledge of both host and symbiont phylogenies, and are therefore often not well adapted to DNA metabarcoding microbial data. Here, we develop a model‐based framework for identifying vertically transmitted microbial taxa. We consider a model for the evolution of microbial sequences on a fixed host phylogeny that includes vertical transmission and horizontal host switches. This model allows estimating the number of host switches and testing for strict vertical transmission and independent evolution. We test our approach using simulations. Finally, we illustrate our framework on gut microbiota high‐throughput sequencing data of the family Hominidae and identify several microbial taxonomic units, including fibrolytic bacteria involved in carbohydrate digestion, that tend to be vertically transmitted.  相似文献   
138.
139.
Understanding the dynamics of foot‐and‐mouth disease virus (FMDV), an endemic and economically constraining disease, is critical in designing control programmes in Africa. This study investigates the evolutionary epidemiology of SAT1 and SAT2 FMDV in Eastern Africa, as well as between cattle and wild African buffalo. Bayesian phylodynamic models were used to analyse SAT1 and SAT2 VP1 gene segments collected between 1975 and 2016, focusing on the SAT1 and SAT2 viruses currently circulating in Eastern Africa. The root state posterior probabilities inferred from our analyses suggest Zimbabwe as the ancestral location for SAT1 currently circulating in Eastern Africa (p = 0.67). For the SAT2 clade, Kenya is inferred to be the ancestral location for introduction of the virus into other countries in Eastern Africa (p = 0.72). Salient (Bayes factor >10) viral dispersal routes were inferred from Tanzania to Kenya, and from Kenya to Uganda for SAT1 and SAT2, respectively. Results suggest that cattle are the source of the SAT1 and SAT2 clades currently circulating in Eastern Africa. In addition, our results suggest that the majority of SAT1 and SAT2 in livestock come from other livestock rather than wildlife, with limited evidence that buffalo serve as reservoirs for cattle. Insights from the present study highlight the role of cattle movements and anthropogenic activities in shaping the evolutionary history of SAT1 and SAT2 in Eastern Africa. While the results may be affected by inherent limitations of imperfect surveillance, our analysis elucidates the dynamics between host species in this region, which is key to guiding disease intervention activities.  相似文献   
140.
为探讨长穗偃麦草E染色体在硬粒小麦背景中的传递特点,利用染色体特异分子标记、基因组原位杂交(GISH)、非变性荧光原位杂交(ND FISH)等方法,对小偃麦8801(AABBEE)与硬粒小麦(AABB)杂交后代中选育的株系Du_No.2和Du_No.4进行了分析。结果表明:(1)分子标记检测株系Du_No.2及Du_No.4分别能扩增出长穗偃麦草2E、4E染色体特异条带。(2)GISH和ND FISH分析显示,株系Du_No.2和Du_No.4分别附加了1条2E和4E染色体,表明株系Du_No.2 和Du_No.4分别为硬粒小麦 长穗偃麦草2E和4E单体附加系。(3)2个株系的减数分裂过程观察发现,后期Ⅰ、Ⅱ和末期Ⅱ都有E染色体分离异常现象,且株系Du_No.2和 Du_No.4的异常率分别为22.24%和36.18%。(4)2个株系分别与硬粒小麦进行正反杂交的后代PCR分析表明, 2E和4E染色体经雄配子的传递率分别为4.41%和2.17%,而通过雌配子的传递率都为零,表明2E和4E染色体在硬粒小麦背景中能通过雄配子传递,但不通过雌配子的传递。该研究为创建全套硬粒小麦 长穗偃麦草双体附加系及代换系提供基础。  相似文献   
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