AXL and AXR1 have redundant functions in RUB conjugation and growth and development in Arabidopsis

Cullin-RING ubiquitin-protein ligases such as the Skp1, cullin, F-box protein (SCF) have been implicated in many growth and developmental processes in plants. Normal SCF function requires that the CUL1 subunit be post-translationally modified by related to ubiquitin (RUB), a protein related to ubiquitin. This process is mediated by two enzymes: the RUB-activating and RUB-conjugating enzymes. In Arabidopsis, the RUB-activating enzyme is a heterodimer consisting of AXR1 and ECR1. Mutations in the AXR1 gene result in a pleiotropic phenotype that includes resistance to the plant hormone auxin. Here we report that the AXL (AXR1-like) gene also functions in the RUB conjugation pathway. Overexpression of AXL in the axr1-3 background complements the axr1-3 phenotype. Biochemical analysis indicates that AXL overexpression restores CUL1 modification to the wild-type level, indicating that AXR1 and AXL have the same biochemical activity. Although the axl mutant resembles wild-type plants, the majority of axr1 axl-1 double mutants are embryo or seedling lethal. Furthermore, the axl-1 mutation reveals novel RUB-dependent processes in embryo development. We conclude that AXR1 and AXL function redundantly in the RUB conjugating pathway.     

小麦光温敏雄性不育相关基因的DDRT－PCR分析及功能预测

 以小麦光温敏雄性不育系BS210为试材,分别在北京顺义（可育环境）和安徽阜阳（不育环境）两种诱导育性表现的生态环境下种植,并于雌雄蕊分化期、药隔形成期、花粉母细胞形成期、四分体期和单核期5个时期提取小穗组织的RNA,利用DDRT-PCR方法分离不育系在光、温因子诱导下的差异表达mRNA,并通过反向Northern 进行验证.对获得的20条差异表达的EST进行了测序和BLAST分析,得到了4个候选基因的片段,对其进行5′Race 扩增、序列分析及功能预测.结果表明：它们分别与水稻的DNA修复重组蛋白基因rad50、小麦穗部表达的LRR重复序列型类受体激酶基因、玉米叶片坏死斑点L1s1基因的序列相似性分别为89%、89%和88%,另外还筛选到1个未知功能的新基因片段,它和rad50分别在可育和不育环境下表达的mRNA具有相同的5′端编码区,但3′端非编码区     

Sensation seeking and men's face preferences

Findings from previous studies suggest that only men who are in good physical condition can afford to pursue high-risk activities and that men who engage in high-risk activities are considered particularly attractive by women. Here, we show that men's interest in high-sensation activities, a personality trait that is known to increase the likelihood of those individuals engaging in high-risk behaviors, is positively related to the strength of their preferences for femininity in women's faces (Studies 1–3) but is not related to the strength of their preferences for femininity in men's faces (Study 2). We discuss these findings as evidence for potentially adaptive condition-dependent mate preferences, whereby men who exhibit signals of high quality demonstrate particularly strong preferences for facial cues of reproductive and medical health in potential mates because they are more likely than lower-quality men to succeed in acquiring such partners.     

粳稻SRAP分子标记遗传群的构建与分析

用超级稻品种‘沈农606’和普通粳稻‘丽江新团黑谷’为亲本杂交获得的102份F_2代单株,通过SRAP分子标记遗传分析,构建了包含14个连锁群,由129个多态性位点组成的水稻连锁图谱,此图谱覆盖基因组长度1671.5 cM,平均图距13.0 cM。连锁群上有17.2%的多态性位点表现偏分离,偏分离标记在连锁群上存在热点区域。     

Rapid evolution of outer egg membrane proteins in the Drosophila melanogaster subgroup: a case of ecologically driven evolution of female reproductive traits

Although sexual selection has been predominantly used to explain the rapid evolution of sexual traits, eggs of oviparous organisms directly face both the challenges of sexual selection as well as natural selection (environmental challenges, survival in niches, etc.). Being the outermost membrane in most insect eggs, the chorion layer is the interface between the embryo and the environment, thereby serving to protect the egg. Adaptive ecological radiations such as divergence in ovipositional substrate usage and host-plant specializations can therefore influence the evolution of eggshell proteins. We can hypothesize that proteins localized on the outer eggshell may be affected to a greater degree by ecological challenges compared with inner eggshell proteins, and therefore, proteins localized in the outer eggshell (chorion membrane) may evolve differently (faster) than proteins localized in the inner egg membrane (vitelline membrane). We compared the evolutionary divergence of vitelline with chorion membrane proteins in species of the melanogaster subgroup and found that chorion proteins as a group are indeed evolving faster than vitelline membrane proteins. At least one vitelline membrane protein (Vm32E), specifically localized on the outer eggshell, is also evolving faster than other vitelline membrane proteins suggesting that all proteins localized on the outer eggshell may be evolving rapidly. We also found evidence that specific codons in chorion proteins cp15 and cp16 are evolving under positive selection. Polymorphism surveys of cp16 revealed inflated levels of divergence relative to polymorphism in specific regions of the gene, indicating that these regions are under strong selection. At the morphological level, we found notable difference in eggshell surface morphologies between specialist (Drosophila sechellia and Drosophila erecta) and generalist species of Drosophila. We do not know if any of the chorion proteins actually interact with spermatozoids, therefore leaving the possibility of rapid evolution through gametic interaction wide open. At this point, however, our results support previous suggestions that divergences in ecology, particularly, ovipositional substrate divergences may be a strong force driving the evolution of eggshell proteins.     

Genetic relationships among Eurasian Puccinellia distans genotypes

Puccinellia distans (Jacq.) Parl. is a common grass species found throughout the world. It can grow in arid and saline environments as well as under toxic boron concentrations. In this work we performed sequence related amplified polymorphism (SRAP) marker analysis on 20 wild P. distans genotypes to understand the genetic relationships among different genotypes and subspecies. We tested 119 SRAP primer pairs and found that 43 were polymorphic. The molecular data were then analyzed to determine the genetic relationships and population structure of the genotypes. We were able to trace the origin of genotypes that were carried to distant locations or gathered for research purposes. We also found that geographical distance between genotypes was not an important determinant of genetic relationships as even distantly located Puccinellia genotypes were closely related. As P. distans is known to be tolerant to salinity stress and toxic mineral concentrations, the findings of this work can be used as a starting point for selection of genotypes that should be tested under such conditions.