Phenotypic and genetic variation between two populations of the Chinese yellow pond turtle, Mauremys mutica (Cantor, 1842)

Mauremys mutica(Cantor,1842)is an endangered species in China.Main phenotypic variations inbody color,body weight,body shape,clutch size,egg size,and hatchling size were revealed betweenthe southern and northern populations.Both populations have the phenomenon of'larger male'sexualsize dimorphism(SSD),especially in the southern population.Furthermore,genetic variations betweenthe two populations were analyzed by RAPD band patterns of 30 random individuals in each population.The average genetic distance was 0.299±0.108 among the samples of two populations.The average ge-netic distance between southern and northern populations was 0.305±0.046.Cluster analysis indicatedthat all the individuals from the southern and northern populations were clustered among themselves toform two distinct clades.A total of 20 population-specific RAPD fragments were scored from 16 primers,and could be used as RAPD markers for distinguishing the southern and the northern population.Basedon the nucleotide sequences of two RAPD markers,two pairs of SCAR primers(SC1-S and SC2-S)weredesigned,which could be used as SCAR markers for the southern population.According to the significantphenotypic and genetic variations,we suggested that the northern population and southern populationmight be considered as two separate taxa,the'northern taxon'and the'southern taxon',and the con-servation should be respectively conducted on the two taxa.

Genetic difference of Chinese horseshoe crab(Tachypleus tridentatus) in southeast coast of China based on mitochondrial COI gene analysis

Population genetic structure and historical demography of Chinese horseshoe crab (T.tridentatus)along southeast coast of China were inferred from the sequence data of mitochondrial cytochrome c oxidase subunit Ⅰ (COI) fragment.The sequence analysis for 964 bp COI fragment was conducted in 28 individuals collected from five localities:Ninghai in Zhejiang Province,Meizhou and Zhangpu in Fujian Province,Beihai of Guangxi Zhuang Autonomous Region and Danzhou of Hainan Province.Sequence variation was relatively low with a total of seven transitions observed.In all localities,Haplotype H3 was the dominant type observed among eight haplotypes defined previously,and was at the center of radiation in Median-Joining network.The prolonged star-like network suggests a signature of population expansions.The level of diversity was low in total,with haplotype diversity ( Hd) being equal to 0.765 and nucleotide diversity (π) being equal to 0.00118,respectively.The genetic structure analysis revealed the significant genetic difference between Ninghai and Danzhou populations.Both mismatch distribution analysis and Fu's Fs test provided consistent inference of historic population expansion.The low genetic diversity of horseshoe crab observed along China coast indicated that urgent measures should be taken to protect this rare marine animal.

创新分子育种科技 支撑我国种业发展

我国新时代社会主要矛盾的转变和粮食安全问题,对现代农业产业体系提出了更高的要求。"农以种为先",但多年来,我国种业自主创新能力不足,育种理念和手段落后,至今依然存在盲目性和主要依赖经验等突出问题。文章概述了我国科技人员创新性提出的分子模块设计育种科技体系,介绍了其理论发展、技术研发和品种设计等方面的探索与实践,并指出分子设计育种将成为未来提高种业自主创新能力,解决种业发展"卡脖子"科技的重要手段。

鱼类遗传育种发展现状与展望

鱼类重要经济性状的分子基础解析及其遗传改良技术的创建驱动了我国水产种业的蓬勃发展。在分析我国鱼类遗传育种的起源、发展和现状的基础上,文章总结了在"分子模块设计育种创新体系"的支持下,以银鲫、草鱼和黄河鲤等为研究对象开展的全基因组解析,性别控制、抗病、耐低氧、饲料高效利用等分子模块解析,以及高产抗病异育银鲫新品种培育的研究进展,由此探讨了在集约化和生态化养殖趋势下未来鱼类遗传育种和水产种业的发展方向。

Molecular basis and genetic improvement of economically important traits in aquaculture animals

Aquaculture has been believed to be a major Chinese contribution to the world. In recent 20 years, genome and other genetic technologies have promoted significant advances in basic studies on molecular basis and genetic improvement of aquaculture animals, and complete genomes of some main aquaculture animals have been sequenced or announced to be sequenced since the beginning of this century. Here, we review some significant breakthrough progress of aquaculture genetic improvement technologies including genome technologies, somatic cell nuclear transfer and stem cell technologies, outline the molecular basis of several economically important traits including reproduction, sex, growth, disease resistance, cold tolerance and hypoxia tolerance, and present a series of candidate trait-related genes. Finally, some application cases of genetic improvement are introduced in aquaculture animals, especially in China, and several development trends are highlighted in the near future.

Genetic basis and breeding application of clonal diversity and dual reproduction modes in polyploid Carassius auratus gibelio

A unisexual species is generally associated with polyploidy, and reproduced by a unisexual reproduction mode, such as gyno- genesis, hybridogenesis or parthenogenesis. Compared with other unisexual and polyploid species, gibel carp (Carassius au- ratus gibelio) has a higher ploidy level of hexaploid. It has undergone several successive rounds of genome polyploidy, and experienced an additional, more recent genome duplication event. More significantly, the dual reproduction modes, including gynogenesis and sexual reproduction, have been demonstrated to coexist in the polyploid gibel carp. This article reviews the genetic basis concerning polyploidy origin, clonal diversity and dual reproduction modes, and outlines the progress in new va- riety breeding and gene identification involved in the reproduction and early development. The data suggests that gibel carp are under an evolutionary trajectory of diploidization. As a novel evolutionary developmental (Evo-Devo) biology model, this work highlights future perspectives about the functional divergence of duplicated genes and the sexual origin of vertebrate animals.

Apolipoprotein C1 regulates epiboly during gastrulation in zebrafish

Apolipoprotein C1(Apoc1)is associated with lipoprotein metabolism,but its physiological role during embryogenesis is largely unknown.We reveal a new function of Apoc1b,a transcript isoform of Apoc1,in epiboly during zebrafish gastrulation.Apoc1b is expressed in yolk syncytial layers and in deep cells of the ventral and lateral region of the embryos.It displays a radial gradient with high levels in the interior layer and low levels in the superficial layer.Knockdown of Apoc1b by injecting antisense morpholino(MO)caused the epiboly arrest in deep cells.Moreover,we show that the radial intercalation and the radial gradient distribution of E-cadherin are disrupted both in Apoc1b knockdown and overexpressed embryos.Therefore,Apoc1b controls epiboly via E-cadherin-mediated radial intercalation in a gradient-dependent manner.