Population structure of king mackerel (Scomberomorus cavalla) around peninsular Florida, as revealed by microsatellite DNA

A total of 1006 king mackerel (Scomberomorus cavalla) representing 20 discrete samples collected between 1996 and 1998 along the east (Atlantic) and west (Gulf) coasts of Florida and the Florida Keys were assayed for allelic variation at seven nuclear-encoded microsatellites. No significant deviations from Hardy-Weinberg equilibrium expectations were found for six of the microsatellites, and genotypes at all microsatellites were independent. Allele distributions at each microsatellite were independent of sex and age of individuals. Homogeneity tests of spatial distributions of alleles at the microsatellites revealed two weakly divergent “genetic” subpopulations or stocks of king mackerel in Florida waters—one along the Atlantic coast and one along the Gulf coast. Homogeneity tests of allele distributions when samples were pooled along seasonal (temporal) boundaries, consistent with the temporal boundaries used currently for stock assessment and allocation of the king mackerel resource, were nonsignificant. The degree of genetic divergence between the two “genetic” stocks was small: on average, only 0.19% of the total genetic variance across all samples assayed occurred between the two regions. Cluster analysis, assignment tests, and spatial autocorrelation analysis did not generate patterns that were consistent with either geographic or spatial-temporal boundaries. King mackerel sampled from the Florida Keys could not be assigned unequivocally to either “genetic” stock. The genetic data were not consistent with current spatial-temporal boundaries employed in stock assessment and allocation of the king mackerel resource. The genetic differences between king mackerel in the Atlantic versus those in the Gulf most likely stem from reduced gene flow (migration) between the Atlantic and Gulf in relation to gene flow (migration) along the Atlantic and Gulf coasts of peninsular Florida. This difference is consistent with findings for other marine fishes where data indicate that the southern Florida peninsula serves (or has served) as a biogeographic boundary.

Nuclear and mitochondrial DNA markers for specific identification of istiophorid and xiphiid billfishes

Independent molecular markers based on mitochondrial and nuclear DNA were developed to provide positive identification of istiophorid and xiphiid billfishes (marlins, spearfishes, sailfish, and swordfish). Both classes of markers were based on amplification of short segments (<1.7 kb) of DNA by the polymerase chain reaction and subsequent digestion with informative restriction endonucleases. Candidate markers were evaluated for their ability to discriminate among the different species and the level of intraspecific variation they exhibited. The selected markers require no more than two restriction digestions to allow unambiguous identification, although it was not possible to distinguish between white marlin and striped marlin with any of the genetic characters screened in our study. Individuals collected from throughout each species’ range were surveyed with the selected markers demonstrating low levels of intraspecific character variation within species. The resulting keys provide two independent means for the forensic identification of fillets and for specific identification of early life history stages.

An examination of spatial and temporal genetic variation in walleye pollock (Theragra chalcogramma) using allozyme, mitochondrial DNA, and microsatellite data

We used allozyme, microsatellite, and mitochondrial DNA (mtDNA) data to test for spatial and interannual genetic diversity in wall-eye pollock (Theragra chalcogramma) from six spawning aggregations representing three geographic regions: Gulf of Alaska, eastern Bering Sea, and eastern Kamchatka. Interpopulation genetic diversity was evident primarily from the mtDNA and two allozyme loci (SOD-2*, MPI*). Permutation tests ˆindicated that FST values for most allozyme and microsatellite loci were not significantly greater than zero. The microsatellite results suggested that high locus polymorphism may not be a reliable indicator of power for detecting population differentiation in walleye pollock. The fact that mtDNA revealed population structure and most nuclear loci did not suggests that the effective size of most walleye pollock populations is large (genetic drift is weak) and migration is a relatively strong homogenizing force. The allozymes and mtDNA provided mostly concordant estimates of patterns of spatial genetic variation. These data showed significant genetic variation between North American and Asian populations. In addition, two spawning aggregations in the Gulf of Alaska, in Prince William Sound, and off Middleton Island, appeared genetically distinct from walleye pollock spawning in the Shelikof Strait and may merit management as a distinct stock. Finally, we found evidence of interannual genetic variation in two of three North American spawning aggregations, similar in magnitude to the spatial variation among North American walleye pol-lock. We suggest that interannual genetic variation in walleye pollock may be indicative of one or more of the following factors: highly variable reproductive success, adult philopatry, source-sink metapopulation structure, and intraannual variation (days) in spawning timing among genetically distinct but spatially identical spawning aggregates.

谷子（Setaria italical L.）叶绿体psbD基因的分子克隆

本文用改良的高盐pH方法提取了龙谷25、龙谷28的叶绿体DNA，用pTB20质粒上含有烟草叶绿体psbD基因的pstI/SacⅡ片段进行了鉴定。并初步发现龙谷25和龙谷28在其叶绿体基因psbD结构序列或附近3'下游区存在者多态性。以pUC19质粒为载体，E.coli HB101为宿主菌，克隆了谷子叶绿体DNA 4.8kb的SacⅠ片段，得到了重组质粒，命名为pSIBD，并对sPIBD重组片段进行了限制图谱解析。

黑麂和费氏麂四种卫星DNA的克隆特征和染色体定位

近年来,分子细胞遗传学研究已基本证实了染色体的串联融合(端粒一着丝粒融合)是麂属动物核型演化的主要重排方式.尽管染色体串联融合的分子机制还不清楚,但通过染色体的非同源重组,着丝粒区域的卫星DNA被认为可能介导了染色体的融合.以前的研究发现在赤麂和小麂染色体的大部分假定的串联融合位点处存在着非随机分布的卫星DNA.然而在麂属的其他物种中,这些卫星DNA的组成以及在基因组中的分布情况尚未被研究.本研究从黑麂和费氏麂基因组中成功地克隆了4种卫星DNA (BMC5、BM700、BM1.1k和FM700),并分析了这些卫星克隆的特征以及在小麂、黑麂、贡山麂和费氏麂染色体上的定位情况.结果表明,卫星Ⅰ和Ⅱ DNA (BMC5,BM700和FM700)的信号除了分布在这些麂属动物染色体的着丝粒区域外,也间隔地分布在这些物种的染色体臂上.其研究结果为黑麂、费氏麂和贡山麂的染色体核型也是从一个2n=70的共同祖先核型通过一系列的串联融合进化而来的假说提供了直接的证据.

云南4个少数民族的随机扩增多态DNA分析

1990年,Williams和Welsh领导的2个小组几乎同时独立地发展起来一项新技术,即随机扩增多态DNA(Random amplified polymorphic DNA,RAPD).该技术通过PCR进行DNA扩增,所用引物是G+C含量为50%—70%的单个随机短引物,这些引物在一定的退火条件下能与基因组DNA中的互补顺序配对,启动DNA的合成.RAPD具有以下特点:(1)无需预先知道受试有机体基因组DNA的序列,因而能应用于所用的生物体;(2)绝大多数

滇金丝猴的随机扩增多态DNA与遗传多样性分析

对6只笼养滇金丝猴(Rhinopithecus bieti)进行了随机扩增多态DNA(RAPD)及遗传多样性分析.用45个10bp随机短引物对每只滇金丝猴的基因组DNA进行了扩增,平均每个个体观察到的RAPD标记约为130个左右,单个引物获得的标记在1～7个之间.80%的RAPD标记表现为无多态的单型性.个体间的遗传距离为0.052,表明笼养滇金丝猴群体的遗传多样性很低.此研究结果与在蛋白多态研究中得到的一致.贫乏的遗传多样性一方面使目前处于濒危境地的滇金丝猴生存情况更加危险,同时其本身也可能是造成目前滇金丝猴濒危的原因之一.另外,通过成对的遗传距离分析,构建了这一群滇金丝猴的谱系关系图,提出了让遗传距离较远的个体间进行交配的笼养繁育计划.

中国黑冠长臂猿的遗传多样性及其分子系统学研究--非损伤取样DNA序列分析

采用非损伤性DNA基因分型技术(Noninvasive DNA genotyping),对我国珍稀灵长类动物黑冠长臂猿11个个体的线粒体DNA(mtDNA)控制区159bp的片段进行了序列分析。根据分子系统树,结合形态学方面的资料,提出对中国黑冠长臂猿新的分类观点,即现生的中国黑冠长臂猿应为3个种(H. concalor; H. leucogenys; H. hainanus),其中 H. concolor含3个亚种(H.c.concolor, H.c.jingdongensis, H.c.furvogaster)。同时,针对该类珍稀动物保护,提出将上述黑冠长臂猿的种和亚种作为不同的进化显著性单元(Evolutionarilly Sigificant Units, ESU)进行保护和遗传管理。