5份粳型亲籼种质的生物学特性及育种利用

本研究以5份自主选育的粳型亲籼种质明恢413、明恢1616、明恢1707、明恢512和明恢509为研究材料,通过对其生物学特性和育种利用进行研究和评价,以期为今后开展粳型亲籼种质资源的选育和籼粳亚种间杂种优势的利用提供理论参考.生物学特性研究结果表明:5份粳型亲籼种质的播始历期偏长,株高适中,直立穗型,穗子小,着粒密,...     

显微多道分光光度法研究受柠檬醛损伤后黄曲霉细胞形态变化

采用从山苍籽油分离出的柠檬醛作为抗菌药物,产毒和无毒的黄曲霉细胞（Aspergillus flavus cell, AFC）作为药物作用的靶,以显微多道分光光度法和显微图像分析法对被该醛所损伤的AFC进行图像捕获,测定受损伤后细胞内吸收光谱、截面积、周长、长轴长及短轴长所发生的变化。发现在410nm和665nm处产毒AFC存在特征吸收峰,受该醛损伤后产毒和无毒AFC的吸收光谱波峰均发生迁移,且峰面积增大;截面积等4类形态参数的数值随柠檬醛浓度升高而减少;为质膜物理化学及细胞内生理生化指标变化提供了理论依据。表明柠檬醛不仅破坏质膜的选择性通透性,而且使细胞质膜结构改变并进入细胞,与靶分子及靶细胞器作用而引发一系列新的生理生化现象的出现。实现对活态细胞受药物作用后形态及生物大分子动态变化的快速、实时、在位的测定,对抗菌药物作用于细胞并使其发生形态结构及靶分子的变化提供了必要的物理参数,在药物抗菌理论及方法研究上具有重要意义。     

Action spectra of phototactic responses of the flea beetle, Phyllotreta striolata

Abstract.  Adult flea beetles, Phyllotreta striolata , show a strong positive phototactic response. The action spectrum of phototaxis of dark-adapted beetles was measured with minimal required light intensity between the wavelength range of 300 nm and 600 nm. Male and female flea beetles showed identical phototacitc behaviours. The beetles were most sensitive to light with peak wavelengths between 350 nm and 430 nm in the morning. In the afternoon and evening, the sensitivity to wavelengths shorter than 430 nm decreased, but they remained most sensitive to 430 nm. These results suggest that changes in sensitivity of the photoreceptors or nervous integration influence the phototactic responses, and that the blue wavelengths are more attractive than others.     

缙云山常绿阔叶林不同演替阶段植物生活型谱比较研究

采用Raunkiner生活型分类系统,对缙云山常绿阔叶林不同演替阶段植物的生活型进行统计,编制了生活型谱,并与其他亚热带地区常绿阔叶林相比较。结果表明,缙云山植被属典型的中亚热带常绿阔叶林植被,高位芽植物占绝对优势,达80％以上,其中小高位芽植物最多,中高位芽与矮高位芽植物次之,藤本植物较丰富。缙云山不同演替阶段的植物的生活型谱不同。随着进展演替阶段的逐渐更替,高位芽植物的比例呈递增趋势,地面芽植物、地下芽植物成分有所减少。高位芽的常绿树种会逐渐代替针叶树种。     

Trait coordination and environmental filters shape functional trait distributions of forest understory herbs

1. Understanding the drivers of trait selection is critical for resolving community assembly processes. Here, we test the importance of environmental filtering and trait covariance for structuring the functional traits of understory herbaceous communities distributed along a natural environmental resource gradient that varied in soil moisture, temperature, and nitrogen availability, produced by different topographic positions in the southern Appalachian Mountains.
2. To uncover potential differences in community‐level trait responses to the resource gradient, we quantified the averages and variances of both abundance‐weighted and unweighted values for six functional traits (vegetative height, leaf area, specific leaf area, leaf dry matter content, leaf nitrogen, and leaf δ¹³C) using 15 individuals of each of the 108 species of understory herbs found at two sites in the southern Appalachians of western North Carolina, USA.
3. Environmental variables were better predictors of weighted than unweighted community‐level average trait values for all but height and leaf N, indicating strong environmental filtering of plant abundance. Community‐level variance patterns also showed increased convergence of abundance‐weighted traits as resource limitation became more severe.
4. Functional trait covariance patterns based on weighted averages were uniform across the gradient, whereas coordination based on unweighted averages was inconsistent and varied with environmental context. In line with these results, structural equation modeling revealed that unweighted community‐average traits responded directly to local environmental variation, whereas weighted community‐average traits responded indirectly to local environmental variation through trait coordination.
5. Our finding that trait coordination is more important for explaining the distribution of weighted than unweighted average trait values along the gradient indicates that environmental filtering acts on multiple traits simultaneously, with abundant species possessing more favorable combinations of traits for maximizing fitness in a given environment.

     

Modelling the effects of climate change on the distribution and production of marine fishes: accounting for trophic interactions in a dynamic bioclimate envelope model

Climate change has already altered the distribution of marine fishes. Future predictions of fish distributions and catches based on bioclimate envelope models are available, but to date they have not considered interspecific interactions. We address this by combining the species‐based Dynamic Bioclimate Envelope Model (DBEM) with a size‐based trophic model. The new approach provides spatially and temporally resolved predictions of changes in species' size, abundance and catch potential that account for the effects of ecological interactions. Predicted latitudinal shifts are, on average, reduced by 20% when species interactions are incorporated, compared to DBEM predictions, with pelagic species showing the greatest reductions. Goodness‐of‐fit of biomass data from fish stock assessments in the North Atlantic between 1991 and 2003 is improved slightly by including species interactions. The differences between predictions from the two models may be relatively modest because, at the North Atlantic basin scale, (i) predators and competitors may respond to climate change together; (ii) existing parameterization of the DBEM might implicitly incorporate trophic interactions; and/or (iii) trophic interactions might not be the main driver of responses to climate. Future analyses using ecologically explicit models and data will improve understanding of the effects of inter‐specific interactions on responses to climate change, and better inform managers about plausible ecological and fishery consequences of a changing environment.     

Autism-related dietary preferences mediate autism-gut microbiome associations

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Theoretical framework of population genetics with somatic mutations taken into account: application to copy number variations in humans

Traditionally, population genetics focuses on the dynamics of frequencies of alleles acquired by mutations on germ-lines, because only such mutations are heritable. Typical genotyping experiments, however, use DNA from some somatic tissues such as blood, which harbors somatic mutations at the current generation in addition to germ-line mutations accumulated since the most recent common ancestor of the sample. This common practice may sometimes cause erroneous interpretations of polymorphism data, unless we properly understand the role of somatic mutations in population genetics. We here introduce a very basic theoretical framework of population genetics with somatic mutations taken into account. It is easy to imagine that somatic mutations at the current generation simply add individual-specific variations, as errors in mutation detection do. Our theory quantifies this increment under various conditions. We find that the major contribution of somatic mutations plus errors is to very rare variants, particularly to singletons. The relative contribution is markedly large when mutations are deleterious. Because negative selection also increases rare variants, it is important to distinguish the roles of these mutually confounding factors when we interpret the data, even after correcting for demography. We apply this theory to human copy number variations (CNVs), for which the composite effect of somatic mutations and errors may not be negligible. Using genome-wide CNV data, we demonstrate how the joint action of the two factors, selection and somatic mutations plus errors, shapes the observed pattern of polymorphism.     

Taylor's law and body size in exploited marine ecosystems

Taylor's law (TL), which states that variance in population density is related to mean density via a power law, and density‐mass allometry, which states that mean density is related to body mass via a power law, are two of the most widely observed patterns in ecology. Combining these two laws predicts that the variance in density is related to body mass via a power law (variance‐mass allometry). Marine size spectra are known to exhibit density‐mass allometry, but variance‐mass allometry has not been investigated. We show that variance and body mass in unexploited size spectrum models are related by a power law, and that this leads to TL with an exponent slightly <2. These simulated relationships are disrupted less by balanced harvesting, in which fishing effort is spread across a wide range of body sizes, than by size‐at‐entry fishing, in which only fish above a certain size may legally be caught.