Novel genetic capacitors and potentiators for the natural genetic variation of sensory bristles and their trait specificity in Drosophila melanogaster

Cryptic genetic variation (CGV) is defined as the genetic variation that has little effect on phenotypic variation under a normal condition, but contributes to heritable variation under environmental or genetic perturbations. Genetic buffering systems that suppress the expression of CGV and store it in a population are called genetic capacitors, and the opposite systems are called genetic potentiators. One of the best‐known candidates for a genetic capacitor and potentiator is the molecular chaperone protein, HSP90, and one of its characteristics is that it affects the genetic variation in various morphological traits. However, it remains unclear whether the wide‐ranging effects of HSP90 on a broad range of traits are a general feature of genetic capacitors and potentiators. In the current study, I searched for novel genetic capacitors and potentiators for quantitative bristle traits of Drosophila melanogaster and then investigated the trait specificity of their genetic buffering effect. Three bristle traits of D. melanogaster were used as the target traits, and the genomic regions with genetic buffering effects were screened using the 61 genomic deficiencies examined previously for genetic buffering effects in wing shape. As a result, four and six deficiencies with significant effects on increasing and decreasing the broad‐sense heritability of the bristle traits were identified, respectively. Of the 18 deficiencies with significant effects detected in the current study and/or by the previous study, 14 showed trait‐specific effects, and four affected the genetic buffering of both bristle traits and wing shape. This suggests that most genetic capacitors and potentiators exert trait‐specific effects, but that general capacitors and potentiators with effects on multiple traits also exist.     

Revisitation of sites surveyed 19 years ago reveals impoverishment of longhorned beetles in natural and planted forests

As planted forests expand in area, they are beginning to dominate landscapes as a matrix and cause the fragmentation of remaining natural forests. To understand and predict the responses of biological assemblages to maturing planted landscapes, examining the effects of forest type (natural vs planted) and forest age on such assemblages is particularly important. Therefore, to document the effects of forest type and age on longhorned beetle assemblages, in 2008 we collected beetles in broad‐leaved natural and cedar planted forests where beetles had also been collected in 1989. Beetle species composition differed greatly between the two forest types in 1989, whereas this difference was less pronounced in 2008. Species richness and total abundance were higher in natural forests than in planted forests in 1989. In 2008, species richness had decreased in both forest types, but the difference between the two forest types had been maintained. Total abundance was also markedly lower in 2008, and the difference between forest types was much smaller. Although larval host plants were not associated with the responses of species to year (forest age or maturation), beetle species whose larvae fed on either broad‐leaved or coniferous trees (or both) exhibited slight preferences for natural forests. These results suggest that longhorned beetle assemblages become impoverished in planted landscapes as the planted matrix matures. Changes in species composition with forest maturation may be difficult to predict based on larval host plants. However, consideration of larval host plants may enable the prediction of changes in species composition caused by the replacement of natural forests by planted forests.     

Novel pure Ca2ZnMoO6 composition with white‐light luminescence

Phosphors with composition Ca₂ZnMoO₆ were synthesized at temperatures of 800–1200°C using the solid‐state method. Analysis of X‐ray diffraction patterns of the Ca₂ZnMoO₆ powders did not reveal a double perovskite structure. When the synthesis temperature was equal to or higher than 800°C, the synthesized Ca₂ZnMoO₆ powders revealed a tetragonal structure (CaMoO₄) rather than an orthorhombic structure (Ca₂ZnMoO₆) and the cubic structure (Sr₂ZnMoO₆) of a double perovskite. The ZnO phase was still observed at a synthesis temperature of 1200°C. The compositions of synthesized Ca₂ZnMoO₆ powders differed from the prepared powder, and the Ca₂ZnMoO₆ phosphors exhibited some important novel features. First, synthesized Ca₂ZnMoO₆ compositions could emit light as a phosphor no activators, called Ca₂ZnMoO₆ phosphors. Effect of synthesis temperature on luminescence properties of these Ca₂ZnMoO₆ phosphors was readily observed, and some important novel features and properties were noted. Second, the phosphors presented only one broad characteristic emission peak in the visible light region. Third, measurement of the chromaticity diagram of the Ca₂ZnMoO₆ phosphors revealed a white‐light source. Through analysis, we determined why the synthesized Ca₂ZnMoO₆ phosphors had just one broad characteristic emission peak.     

Widespread introgression does not leak into allotopy in a broad sympatric zone

Species that overlap over a large part of their range and habitat requirements are challenging for the study of speciation and hybridization. In this respect, the study of broadscale introgressive hybridization has raised recent interest. Here we studied hybridization between two closely related amphibians Lissotriton helveticus and Lissotriton vulgaris that reproduce over a wide sympatric zone. We used mitochondrial and microsatellite markers on 1272 individuals in 37 sites over Europe to detect hybrids at the individual-level and to analyse Hardy-Weinberg and linkage disequilibria at the population-level. Morphological traits showed a strong bimodal distribution. Consistently, hybrid frequency was low (1.7%). We found asymmetric introgression with five times more hybrids in L. vulgaris than in L. helveticus, a pattern probably explained by an unequal effective population size in a study part wherein L. helveticus numerically predominates. Strikingly, significant levels of introgression were detected in 73% of sites shared by both species. Our study showed that introgression is widespread but remains confined to the sites where the two species reproduce at the same time. This pattern may explain why these species remain genetically distinct over a broad sympatric zone.     

土壤微生物群落结构对中亚热带三种典型阔叶树种凋落物分解过程的响应

通过小盆模拟试验研究了南方红壤丘陵区典型阔叶树种香樟、白栎和青冈的凋落物分解过程中土壤微生物群落结构的异同。结果表明:(1)凋落物含氮量:白栎>香樟>青冈;碳、木质素的含量以及碳/氮比、木质素/氮比:青冈>香樟>白栎;分解速率:白栎>香樟>青冈;(2)随着凋落物分解的进程,土壤微生物群落16 ∶ 0、15 ∶ 0、i16 ∶ 0、a17 ∶ 0、17 ∶ 0、18 ∶ 2ω6,9c和10Me18 ∶ 0的含量上升,18 ∶ 0、14 ∶ 0、16 ∶ 1ω7c、18 ∶ 1ω7c、cy19 ∶ 0、i19 ∶ 0和10Me19 ∶ 0的含量下降,饱和直链脂肪酸/单不饱和脂肪酸、革兰氏阳性菌/革兰氏阴性菌以及cy19 ∶ 0/18 ∶ 1ω7c的比值都显著上升。(3)两个时期白栎凋落物处理土壤16 ∶ 0、15 ∶ 0、a15 ∶ 0、i16 ∶ 0、a17 ∶ 0、 17 ∶ 0、cy19 ∶ 0、18 ∶ 2ω6,9c、18 ∶ 1ω9c和10Me18 ∶ 0的含量显著高于香樟和青冈凋落物处理的土壤,细菌、真菌的磷脂脂肪酸含量以及磷脂脂肪酸总量显著高于香樟和青冈凋落物处理的土壤。随着阔叶凋落物的分解,变化的土壤环境对土壤微生物群落的胁迫增强,土壤微生物群落结构发生显著变化。与香樟和青冈的凋落物相比,白栎凋落物碳/氮比和木质素/氮比低、分解快,能显著改善土壤微生物群落结构,更有利于土壤肥力提高和生态系统养分循环的改善。     

Patchy distribution of flexible genetic elements in bacterial populations mediates robustness to environmental uncertainty

The generation and maintenance of genetic variation seems to be a general ecological strategy of bacterial populations. Thereby they gain robustness to irregular environmental change, which is primarily the result of the dynamic evolution of biotic interactions. A benefit of maintaining population heterogeneity is that only a fraction of the population has to bear the cost of not (yet) beneficial deviation. On evolutionary time frames, an added value of the underlying mechanisms is evolvability, i.e. the heritable ability of an evolutionary lineage to generate and maintain genetic variants that are potentially adaptive in the course of evolution. Horizontal gene transfer is an important mechanism that can lead to differences between individuals within bacterial populations. Broad host-range plasmids foster this heterogeneity because they are typically present in only a fraction of the population and provide individual cells with genetic modules newly acquired from other populations or species. We postulate that the benefit of robustness on population level could balance the cost of transfer and replication functions that plasmids impose on their hosts. Consequently, mechanisms that make a subpopulation conducive to specific conjugative plasmids may have evolved, which could explain the persistence of even cryptic plasmids that do not encode any traits.     

云南普洱季风常绿阔叶林非结构性碳水化合物及其组分随环境的变化

为探索植物非结构性碳水化合物(NSC)组分随环境的变化特征,在云南普洱季风常绿阔叶林原始林选取6块60m×60m样地进行野外调查,各样地分别选择重要值前10位的物种进行取样,通过测定不同样地主要物种的NSC及其组分和样地环境因素,分析其非结构性碳水化合物与环境的关系。结果显示:(1)云南普洱季风常绿阔叶林植物中总体淀粉、可溶性糖、NSC含量分别为13.91%、3.31%、17.21%,淀粉和NSC含量在各器官中排序依次为根干枝叶,而可溶性糖含量排序依次为叶根枝干;淀粉、可溶性糖、NSC含量变异最大值分别为叶片19.09%、干15.32%和根16.30%。(2)云南普洱季风常绿阔叶林植物不同器官中淀粉含量仅与凋落物厚度、土壤pH及速效钾、全钾存在显著正或负相关关系,可溶性糖含量与海拔高度及土壤理化性质存在显著正或负相关关系;但茶梨与红椎中淀粉含量与土壤有效磷或全磷存在显著正相关关系,茶梨各器官中可溶性糖含量与所有环境因子均无显著相关性,红椎根中可溶性糖含量与pH值、枝中可溶性糖含量与全钾分别呈显著负相关关系;短刺椎各器官中淀粉含量与所有环境因子均无显著相关性,可溶性糖含量则与水解性氮、有效磷含量呈显著负相关关系,与坡度、全钾含量、凋落物厚度呈显著正相关关系。(3)单因素回归分析显示,海拔高度、有机质、水解性氮、全氮影响季风常绿阔叶林的总体可溶性糖含量,而其淀粉含量则主要受pH值影响。研究发现,季风常绿阔叶林NSC受环境因子影响,但不同NSC组分的环境影响因子不同。