一株人源性轮状病毒的分离及适应性培养

目的:研究轮状病毒野毒株的分离方法、组织培养适应条件及相应生物学性质.方法:对收集的样品采用胶体金、PCR、PAGE进行轮状病毒定性检测.阳性样品按常规方法处理并进行组织培养分离,对不同传代样品做基因组图谱、基因序列、病毒增殖动力学分析评价,采用轮状病毒P[8]G1型阳性血清进行病毒中和鉴别试验.结果:通过检测为A组轮状病毒,基因组为4∶2∶3∶2排列,基因分型G1P [8]型,在MA104细胞中传代后转至Vero细胞上适应培养可观察到CPE;电镜观察可见典型轮状病毒形态.毒株在Vero细胞上增殖到第10代,复制稳定,且感染性滴度达到7.25 log CCID50/ml,增殖高峰为96h.中和鉴别试验证实病毒培养液只包含轮状病毒,无其他病毒污染.结论:从腹泻样品中分离得到一株人源轮状病毒毒株,命名为ZTR-68株,该分离株具有良好的组织培养适应性,遗传稳定性,为进一步研究其生物学性质和疫苗制备提供了基础.     

Widespread Prion-Based Control of Growth and Differentiation Strategies in Saccharomyces cerevisiae

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Focus: Allergic Diseases and Type II Immunity: Intricate Relationship Between Adaptive and Innate Immune System in Allergic Contact Dermatitis

Allergic contact dermatitis (ACD) is a complex immunological allergic disease characterized by the interplay between the innate and adaptive immune system. Initially, the role of the innate immune system was believed to be confined to the initial sensitization phase, while adaptive immune reactions were linked with the advanced elicitation phase. However, recent data predicted a comparatively mixed and interdependent role of both immune systems throughout the disease progression. Therefore, the actual mechanisms of disease progression are more complex and interlinked. The aim of this review is to combine such findings that enhanced our understanding of the pathomechanisms of ACD. Here, we focused on the main cell types from both immune domains, which are involved in ACD, such as CD4⁺ and CD8⁺ T cells, B cells, neutrophils, and innate lymphoid cells (ILCs). Such insights can be useful for devising future therapeutic interventions for ACD.     

Adaptive traits of bark and ambrosia beetle-associated fungi

A phenotype is the expression of interactions between species genotype and environment. We quantified the contributions of ecological and phylogenetic associations to phenotypic variation in Geosmithia fungi. Geosmithia are symbiotic beetle-associated saprotrophs with a range of life histories and host specificities, including obligate nutritional beetle mutualists (ambrosia fungi) and phytopathogens. We hypothesized that: (1) species phenotypes are better explained by their ecology than by their phylogenetic relationships; (2) niche specialization was accompanied by enzymatic capability losses; and (3) ambrosia Geosmithia species have higher nutritional quality and antibiotic capabilities than species with facultative symbioses. Our results confirmed that long-term co-evolved specialists have reduced metabolic breadth in comparison to generalists. Phytopathogenic G. morbida produces unique enzyme suites with affinity to ligno-cellulose. Mycelia of ambrosia fungi contain large amounts of oleic fatty acid with nutritive and possibly allelopathic function. Overall, our results indicate that Geosmithia ecology have greater effect on species phenotype than their phylogenetic relationships.     

Adaptive response of human lymphocytes for the repair of radon-induced chromosomal damage

In human lymphocytes low doses of X-rays can decrease the number of chromatid deletions induced by subsequent high doses of sparsely ionizing X-rays. Because of the concern with the carcinogenic effects of low doses of -particles from radon in homes, experiments were carried out to see if low doses of X-rays could also decrease the yield of chromosomal aberrations induced by subsequent exposure to radon. Human peripheral blood lymphocytes were irradiated with low doses of X-rays (2 cGy) at 48 h of culture, exposed to radon at 72 h of culture, and analyzed for the presence of chromatid aberrations at subsequent intervals. The frequency of chromatid aberrations induced by radon alone increased with time after exposure, indicating exaggerated differences in the stage sensitivity of cell cycle stages to high-LET radiation. Furthermore, the numbers of aberrations per cell did not follow a Poisson distribution but were over dispersed, as might be expected since high-LET radiations have a high relative biological effectiveness compared with low-LET radiations. Nevertheless, lymphocytes exposed to 2 cGy of X-rays before radon exposure contained approximately one-half the number of chromatid deletions compared with lymphocytes treated with radon alone and analzed at the same time. Thus, the putative chromosomal repair mechanism induced by low doses of sparsely ionizing radiation is also effective in reducing chromosomal aberrations induced by radon, which hitherto had been thought to be relatively independent of repair processes.     

Techniques for adaptive prostate radiotherapy

Variations in the position and shape of the prostate make accurate setup and treatment challenging. Adaptive radiation therapy (ART) techniques seek to alter the treatment plan, at one or more points throughout the treatment course, in response to changes in patient anatomy observed between planning and pre-treatment images. This article reviews existing and developing ART techniques for prostate cancer along with an overview of supporting in-room imaging technologies. Challenges to the clinical implementation of adaptive radiotherapy are also discussed.     

Additive genetic variance for lifetime fitness and the capacity for adaptation in an annual plant

The immediate capacity for adaptation under current environmental conditions is directly proportional to the additive genetic variance for fitness, V_A(W). Mean absolute fitness, , is predicted to change at the rate , according to Fisher's Fundamental Theorem of Natural Selection. Despite ample research evaluating degree of local adaptation, direct assessment of V_A(W) and the capacity for ongoing adaptation is exceedingly rare. We estimated V_A(W) and in three pedigreed populations of annual Chamaecrista fasciculata, over three years in the wild. Contrasting with common expectations, we found significant V_A(W) in all populations and years, predicting increased mean fitness in subsequent generations (0.83 to 6.12 seeds per individual). Further, we detected two cases predicting “evolutionary rescue,” where selection on standing V_A(W) was expected to increase fitness of declining populations (< 1.0) to levels consistent with population sustainability and growth. Within populations, inter‐annual differences in genetic expression of fitness were striking. Significant genotype‐by‐year interactions reflected modest correlations between breeding values across years, indicating temporally variable selection at the genotypic level that could contribute to maintaining V_A(W). By directly estimating V_A(W) and total lifetime , our study presents an experimental approach for studies of adaptive capacity in the wild.     

ADAPTIVE WALKS AND DISTRIBUTION OF BENEFICIAL FITNESS EFFECTS

We study the adaptation dynamics of a maladapted asexual population on rugged fitness landscapes with many local fitness peaks. The distribution of beneficial fitness effects is assumed to belong to one of the three extreme value domains, viz. Weibull, Gumbel, and Fréchet. We work in the strong selection‐weak mutation regime in which beneficial mutations fix sequentially, and the population performs an uphill walk on the fitness landscape until a local fitness peak is reached. A striking prediction of our analysis is that the fitness difference between successive steps follows a pattern of diminishing returns in the Weibull domain and accelerating returns in the Fréchet domain, as the initial fitness of the population is increased. These trends are found to be robust with respect to fitness correlations. We believe that this result can be exploited in experiments to determine the extreme value domain of the distribution of beneficial fitness effects. Our work here differs significantly from the previous ones that assume the selection coefficient to be small. On taking large effect mutations into account, we find that the length of the walk shows different qualitative trends from those derived using small selection coefficient approximation.     

Phylogenetic analysis of ecological and morphological diversification in Hispaniolan trunk-ground anoles (Anolis cybotes group)

Abstract Anolis lizards in the Greater Antilles partition the structural microhabitats available at a given site into four to six distinct categories. Most microhabitat specialists, or ecomorphs, have evolved only once on each island, yet closely related species of the same ecomorph occur in different geographic macrohabitats across the island. The extent to which closely related species of the same ecomorph have diverged to adapt to different geographic macro-habitats is largely undocumented. On the island of Hispaniola, members of the Anolis cybotes species group belong to the trunk-ground ecomorph category. Despite evolutionary stability of their trunk-ground microhabitat, populations of the A. cybotes group have undergone an evolutionary radiation associated with geographically distinct macrohabitats. A combined phylogeographic and morphometric study of this group reveals a strong association between macrohabitat type and morphology independent of phylogeny. This association results from long-term morphological evolutionary stasis in populations associated with mesic-forest environments ( A. c. cybotes and A. marcanoi ) and predictable morphometric changes associated with entry into new macrohabitat types (i.e., xeric forests, high-altitude pine forest, rock outcrops). Phylogeographic analysis of 73 new mitochondrial DNA sequences (1921 aligned sites) sampled from 68 geographic populations representing 12 recognized species and subspecies diagnoses 16 allopatric or parapatric groupings of populations differing from each other by 5–18% sequence divergence. At least some of these groupings appear to have attained species-level divergence from others. Evolutionary specialization to different macrohabitat types may be a major factor in the evolutionary diversification of Greater Antillean anoles.