INCIPIENT SPECIATION OF SEA STAR POPULATIONS BY ADAPTIVE GAMETE RECOGNITION COEVOLUTION

Reproductive isolation—the key event in speciation—can evolve when sexual conflict causes selection favoring different combinations of male and female adaptations in different populations. Likely targets of such selection include genes that encode proteins on the surfaces of sperm and eggs, but no previous study has demonstrated intraspecific coevolution of interacting gamete recognition genes under selection. Here, we show that selection drives coevolution between an egg receptor for sperm (OBi1) and a sperm acrosomal protein (bindin) in diverging populations of a sea star (Patiria miniata). We found positive selection on OBi1 in an exon encoding part of its predicted substrate‐binding protein domain, the ligand for which is found in bindin. Gene flow was zero for the parts of bindin and OBi1 in which selection for high rates of amino acid substitution was detected; higher gene flow for other parts of the genome indicated selection against immigrant alleles at bindin and OBi1. Populations differed in allele frequencies at two key positively selected sites (one in each gene), and differences at those sites predicted fertilization rate variation among male–female pairs. These patterns suggest adaptively evolving loci that influence reproductive isolation between populations.     

Preface

The nervous system is among the most complicated systems in the universe. Although it has been intensively studied during the past decades or even centuries, the complicity     

2型糖尿病小鼠食道菌群的结构分析

人体内庞大的微生物群体对人体有着巨大的影响.越来越多的数据表明,肠道菌群与肥胖症、糖尿病等代谢性疾病的发生密切相关.食道菌群结构对研究胃肠道及整个消化 系统菌群结构至关重要.针对10只2型糖尿病模型小鼠及10只正常对照小鼠食道样本,进行变性梯度凝胶电泳（DGGE）和克隆测序分析食道菌群结构.结果发现,实验组小鼠与对照组小鼠食道菌群多样性指数与丰富度指数存在显著差异,均匀度指数无显著差 异.说明正常小鼠较2型糖尿病小鼠食道菌群种类及数量较大,优势菌种类及相对含量相似.测序结果显示,正常小鼠食道内含乳杆菌属细菌,而患病小鼠食道内不含乳杆菌属细菌或含量极低.提示乳杆菌属细菌与2型糖尿病密切相关,实验结果对研究糖尿病发病机理及并发症治疗有重要意义.     

内侧额叶负波受负性情绪下责任感影响：最后通牒任务的ERP研究

采用事件相关电位技术探讨人脑的内侧额叶负波在最后通牒任务中是否受不同情绪状态的影响并且其差异是否与责任感这一人格特质有关.结果发现,相对于负性情绪及公平情境,MFN的波幅在正性情绪和不公平情境中显著较大;相对于正性情绪和公平情境,在负性情绪和不公平情境中责任感人格维度得分越高,MFN波幅越正.结果表明,MFN反映的是对决策情境的认知评价且正性情绪更有利于对决策情境的觉知;责任感通过削弱由不利情境带来的认知反应来压制个体对于决策情境的敏感性,以追求更好的决策结果.这为MFN在真实的社会互动任务中表现出来的差异提供了具有较高生态学效度的神经电理学证据.     

基于复杂网络的蛋白质结构域组进化分析

结构域重组与序列复制、变异一起,推动了生命的进化。文章应用复杂网络理论比较分析了不同复杂程度的真核生物体中蛋白质结构域组的进化规律。结果表明大量的结构域(约34%)被基因组共享,而结构域的相邻二元组合却具有很大的物种特异性。结构域组合网络呈现无尺度特性,其幂率分布及平均连接度在一定程度上反映了物种的复杂性;网络的聚集系数远高于相同度分布的随机网络(P=0.0096),聚集系数与度呈现幂率分布,这说明网络服从模块化层次式组织规律。最后以人类基因组为例,初步探索了网络模块与功能的关系,发现网络模块中的结构域具有不同程度的功能一致性。