Comparative mitochondrial genome analysis of Varunidae and its phylogenetic implications

Complete mitochondrial genomes(mitogenomes)can indicate phylogenetic relationships,as well as useful information for gene rearrangement mechanisms and molecular evolution.Currently,the phylogenetic location of the genus Varuna(Brachyura:Varunidae)has not been well resolved mainly because of limited representatives(only two extant species).Here,we determined a new mitogenome of this genus(Varuna litterata)and added the published mitogenomes to reconstruct the phylogeny of Varunidae.The 16368-bp mitogenome contains the entire set of 37 genes and a putative control region.The characteristics of this newly sequenced mitogenome were described and compared with the other 15 Varunidae mitogenomes.All 16 analyzed mitogenomes have identical gene order and similar molecular features.The sliding window and genetic distance analyses demonstrate highly variable nucleotide diversity,with comparatively low variability of COI and COII,and high variability of ND6.The nonsynonymous/synonymous substitution rates(dN/dS ratio)analysis shows that all 13 PCGs are under purifying selection and ATP8 gene evolves under the least selective pressure.Twelve tRNA genes,two rRNAs,one PCG,and the putative control region are found to be rearranged with respect to the pancrustacean ground pattern gene order.Tandem duplication/random loss model is adopted to explain the large-scale gene rearrangement events occurring in Varunidae mitogenomes.Phylogenetic analyses show that all Varunidae species are placed into one group,and form a sister clade with Macrophthalmidae.Nevertheless,the phylogenetic relationships within Varunidae are not completely consistent based on the two different datasets used in this study.These findings will contribute to a better understanding of gene rearrangement and molecular evolution in Varunidae mitogenomes,as well as provide insights into the phylogenetic studies of Brachyura.

长江口中华绒螯蟹与其它几种同科蟹的同工酶比较

对长江口中华绒螯蟹、天津厚蟹、无齿相手蟹、红螯相手蟹和字纹弓蟹等五种蟹的肌肉、肝进行了６种同工酶的聚丙烯酰胺凝胶电泳。结果表明，五种蟹的同工酶酶谱存在明显的物种特异性和组织特异性，种间同工酶差异与它们的分类地位一致。

白纹方蟹、字纹弓蟹与角眼沙蟹rDNA序列变异及结构分析

用特异性引物分别扩增、测得白纹方蟹、字纹弓蟹和角眼沙蟹18SrDNA序列片段长度为826bp、825bp和833bp；分析得出3种蟹18SrDNA序列的A＋T碱基百分含量基本相同，其平均含量为49．3％，略低于G＋C的百分含量（50．7%）；3条18SrDNA序列对位排列后共836位点，其中存在20个变异位点，包括插入／缺失位点13个，转换4个，颠换3个；并通过RNAstructure软件对变异较大的第601～836位点序列进行了二级结构预测。

吠陀经典中伐楼那神的天王地位与雅利安特征

在印度神话中,伐楼那是雅利安人游牧阶段主神,但他被吠陀诗人收入吠陀诗歌加以赞颂。从这些颂诗里,我们可以看到伐楼那作为宇宙天王的地位、权威、统治政策和赢得的荣耀。到了吠陀时代后期,伐楼那的天王地位为因陀罗撼动并取代,标志着统治秩序的重建。天王易位,这里面包含了现实生活的需要、宗教及历史方面的因素。此外,从《吠陀》中对伐楼那神为数不多的颂诗中,我们可以窥见伐楼那神在生存环境、生存方式和创造活动方面所体现出的雅利安特征。