基于ISSR标记的扁玉螺(Neverita didyma)自然居群遗传结构

利用ISSR分子标记技术,对采自大连（DL）、烟台（YT）及青岛（QD）近海的扁玉螺3个自然居群的遗传结构和遗传多样性进行了分析。用13个引物对90只个体进行了PCR扩增,共检测到161个位点,3个居群的多态位点比例为74.53%～85.09%,各居群遗传多样性水平的高低依次为YT〉QD〉DL。扁玉螺在物种水平上的Nei’s基因多样性指数和Shannon’s信息指数分别为0.3395和0.5113,在居群水平上分别为0.2811和0.4189,显示出扁玉螺有着较高的遗传多样性。AMOVA分子变异分析表明,扁玉螺的遗传变异有27.16%发生在居群间,72.84%发生在居群内,居群内的遗传变异大于居群间的遗传变异。扁玉螺3个居群间的遗传分化系数（Gst）为0.1720,基因流（Nm）为2.4063,Nei’s遗传距离平均值为0.1228,表明扁玉螺居群间虽然存在着一定程度的遗传分化,但仍属于种内正常分化的范畴。上述结果为保护和利用扁玉螺资源提供了科学依据。     

云南南部不同种源地小桐子遗传多样性的ISSR分析

应用ISSR分子标记方法对采自云南的8个居群的小桐子(Jatropha curcas)共158个个体进行遗传多样性分析。8个ISSR引物共扩增到了67个位点,其中61个是多态性位点。分析结果表明:(1)云南小桐子的遗传多样性水平很高。在物种水平上,平均每个位点的多态位点百分率PPB=91.04%,有效等位基因数Ne=1.5244,Nei′s基因多样性指数He=0.3070,Shannon多样性信息指数Ho=0.4618;在居群水平上,PPB=55.04%,Ne=1.3826,He=0.2171,Shannon多样性信息指数Ho=0.3178。(2)居群间的遗传分化低于居群内的遗传分化。基于Nei′s遗传多样性分析得出的居群间遗传多样性分化系数Gst=0.2944。AMOVA分析显示:云南小桐子的遗传变异主要存在于居群内,占总变异的63.50%,居群间的遗传变异占36.50%。(3)居群间的地理距离及遗传一致度并不存在相关性。鉴于以上指标,我们推测云南小桐子可能来自不同的地区。     

濒危植物连香树居群的遗传多样性和遗传分化研究

利用ISSR分子标记技术对濒危植物连香树10个居群的遗传多样性和遗传变异进行了分析,结果表明:连香树物种水平遗传多样性较高,多态位点百分率(PPB)达到69.59%,Nei’s基因多样性指数(H)和Shannon信息指数(I)分别为0.231 3和0.351 4;而在居群水平上,多态位点百分率(PPB)为30.61%,Nei’s基因多样性指数(H)和Shannon信息指数(I)分别为0.115 6和0.173 3。遗传变异分析表明,居群间遗传分化程度高,遗传分化系数(GST)为0.500 3,居群间基因流Nm为0.527 3。Mantel检测,居群间的遗传距离和地理距离之间不存在显著的相关性。生境的片断化使居群间的基因流受阻,可能是导致居群间高遗传分化和居群水平低遗传多样性的主要原因。     

西双版纳地区流苏石斛遗传多样性的ISSR分析

采用ISSR分子标记技术,对西双版纳分布的兰科濒危植物流苏石斛（Dendrobium fimbriatum）5个居群共114个个体的遗传多样性进行了研究。从100条引物中筛选出了12条用于扩增,共检测到117个位点,其中105个为多态位点。分析结果表明,流苏石斛居群水平遗传多样性较低。在物种水平上,流苏石斛多态位点百分率PPB为89．74％,Nei’s基因多样性指数日为0．3227,Shannon’s多样性信息指数见。为0．4779;在居群水平上,各个居群的多态位点百分率PPB差异较大（6．84％～39．32％）,平均值为23．93％,Nei’s基因多样性指数H为0．0871,各个居群的Shannon’s多样性信息指数见平均为0．1290。AMOVA分析的结果显示,流苏石斛的遗传变异大多数存在于居群间,占总遗传变异的74．79％。基于Nei’s遗传多样性分析得出的居群间遗传分化系数Gst=0．7443。各居群间的Nei’s遗传一致度（I）范围为0．5882～0．8331。Mantel检测发现,居群间的遗传距离和地理距离之间无显著的正相关关系（r=0．2419,P=0．2416）。鉴于流苏石斛的遗传多样性现状和居群遗传结构,我们建议对流苏石斛居群所有个体实施及时的就地保护,同时建立迁地保护居群,促进基因交流。     

华中特有珍稀植物裸芸香的AFLP遗传多样性分析

采用选择性扩增片段多态性(AFLP)方法对华中特有单种属植物裸芸香(Psilopeganum sinense)的8个自然居群的遗传多样性进行了检测与分析。结果表明:裸芸香的遗传多样性较低,且居群内遗传多样性显著低于物种水平遗传多样性。筛选出的5对引物共得到180个位点,76个为多态位点,多态位点百分率为42.2%,8个居群多态位点百分率为:3.3%～16.7%,居群平均多态位点百分率为9.4%;8个居群Nei多样性指数为0.01987～0.06987,Shannon’s多样性指数为0.0197～0.0816。居群间分化系数Gst=0.5069,居群间基因流为0.2432,不足以维持居群间的基因交流及现有的遗传结构。AMOVA分析表明总遗传变异的13.17%存在于4个地理区域之间,50.45%存在于地理区域内的居群间,36.38%的遗传变异存在于居群内个体间。NTSYS分析表明遗传距离与地理距离不存在相关关系。UPGMA聚类结果表明长江南北两岸的居群并没有产生明显分化。最后,分析了裸芸香的濒危原因并提出了有效的保育措施。     

都支杜鹃遗传多样性的ISSR分析

通过ISSR分子标记对都支杜鹃(Rhododendron shanii)5个居群114个个体的遗传多样性进行了分析。8个引物共检测到69个位点,其中多态位点36个,多态位点百分率 （P） 为52.17%;物种水平的Shannon多样性指数（I）为0.2536,Nei指数（H）为0.1659;居群水平的P、I和H分别平均为32.46%、0.1955和0.1344;Nei’s基因分化系数GST=0.1845,基因流Nm=2.2104;遗传结构的AMOVA分析显示,总的遗传变异中88.3%存在于居群内,11.7%存在于居群间;PCA分析和Splite Tree构建的NJ树均显示居群间分化小;遗传距离与地理距离显著相关。较强的基因流、多年生木本及异交与分布区狭窄等可能是导致都支杜鹃遗传多样性较低的主要原因。目前该种的保护应以就地保护为主,尤其要注意对大居群的保护。     

广西地不容种质资源的ISSR分析

采用简单序列重复区间扩增(ISSR)分子标记技术对广西地不容3个野生居群和1个引种居群共92个个体进行了遗传多样性研究。10个引物共扩增出61条带,其中60条具多态性,多态性位点百分率为98.36%。4个居群多态性百分率在73.77%～86.89%。Nei’s基因多样性指数(H)为0.3379,Shannon信息多样性指数(Ⅰ)为0.5055。3个野生居群Nei’s遗传分化系数(Gst)表明:83.87%遗传变异分布在居群内,16.13%的遗传变异分布在居群间。引种居群与3个野生居群间的遗传一致度达0.8846。引种居群有效地保护了广西地不容的遗传多样性。     

云南长尖叶蔷薇自然居群遗传多样性分析

采用SSR标记对云南地区的8个长尖叶蔷薇天然居群进行了遗传多样性分析。结果显示:所选用的14对SSR引物,共检测到77个等位位点;在物种水平上,总居群的Nei’s基因多样性指数(He)和香农指数(I)分别为0.3139和0.4747;该居群内遗传变异(65.47%)大于居群间遗传变异(34.53%),说明居群内变异是其居群的主要变异来源;利用Popgene计算出两两居群间的Nei’s遗传一致度(I)和遗传距离(D),其范围分别为0.7879～0.8986和0.1070～0.2384,依据遗传距离可将8个居群分为3组,8个居群并没有严格依据地理距离的远近而聚类;海拔与Nei’s基因多样性的相关系数为0.8771,呈显著正相关。研究结果表明,云南地区的长尖叶蔷薇居群遗传多样性较高,居群间遗传变异存在中度的遗传分化。基于得到的居群遗传信息,建议采取就地保护为主的保护策略,但当个别居群野外的生存环境被自然或者人为因素破坏时,建议采取迁地保护的保护策略。     

西双版纳地区流苏石斛遗传多样性的ISSR 分析

采用ISSR 分子标记技术, 对西双版纳分布的兰科濒危植物流苏石斛( Dendrobium fimbriatum) 5 个居群共114 个个体的遗传多样性进行了研究。从100 条引物中筛选出了12 条用于扩增, 共检测到117 个位点, 其中105 个为多态位点。分析结果表明, 流苏石斛居群水平遗传多样性较低。在物种水平上, 流苏石斛多态位点百分率PPB 为89 .74% , Nei′s 基因多样性指数H 为0 . 3227 , Shannon′s 多样性信息指数Hsp 为0 . 4779 ; 在居群水平上, 各个居群的多态位点百分率PPB 差异较大( 6.84% ～ 39.32% ) , 平均值为23.93% , Nei′s 基因多样性指数H 为0 . 0871 , 各个居群的Shannon′s 多样性信息指数Ho 平均为0.1290。AMOVA 分析的结果显示, 流苏石斛的遗传变异大多数存在于居群间, 占总遗传变异的74 . 79%。基于Nei′s遗传多样性分析得出的居群间遗传分化系数Gst = 0 . 7443。各居群间的Nei′s 遗传一致度( I) 范围为0 . 5882～0 . 8331。Mantel 检测发现, 居群间的遗传距离和地理距离之间无显著的正相关关系( r= 0.2419, P=0.2416) 。鉴于流苏石斛的遗传多样性现状和居群遗传结构, 我们建议对流苏石斛居群所有个体实施及时的就地保护, 同时建立迁地保护居群, 促进基因交流。     

内蒙古扁蓿豆遗传多样性的ISSR分析

应用ISSR分子标记对分布于内蒙古不同地区的扁蓿豆(Medicago ruthenica)8个地理种群进行了遗传多样性研究.结果表明:扁蓿豆具有较高的遗传多样性;15个引物共扩增出363个位点,物种水平上Nei s基因多样性指数为0.198 9,Shannon多样性指数为0.303 7;种内总基因多样性为0.308 6,种群内基因多样性为0.198 9,64.45%的遗传变异存在于种群内,35.55%的遗传变异存在于种群间,种群间的遗传分化系数为0.355 5,基因流为0.906 4,8个种群间基因交流较少,遗传分化较强.UPGMA遗传距离聚类结果表明,生态地理条件相似的种群优先聚集.     

The complete mitochondrial genome of Solen strictus (Bivalvia: Solenidae)

In this paper, we determined the complete mitochondrial genome of Solen strictus (Bivalvia: Solenidae). The whole mitogenome of S. strictus is 16,535?bp in length with a base composition of 21.7% A, 41.0% T, 25.6% C, and 11.7% G and contains 12 protein-coding genes (atp8 is missing), 2 ribosomal RNA genes, 22 transfer RNA genes, and a major non-coding region (MNR). Some peculiar patterns including tandem repeats and microsatellite-like elements are found in the MNR of S. strictus.     

Two-domain arginine kinases from the clams Solen strictus and Corbicula japonica: exceptional amino acid replacement of the functionally important D(62) by G

Arginine kinases (AKs) isolated from the adductor muscle of the clams Solen strictus and Corbicula japonica have relative molecular masses of 80 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in contrast to the 40 kDa AKs found in Mollusca and Arthropoda. The cDNAs encoding Solen and Corbicula AKs have open reading frames of 2175 nucleotides (724 amino acid protein) and 2172 nucleotides (723 amino acid protein), respectively. The amino acid sequence clearly indicates that Solen and Corbicula AKs have a two-domain structure: the first-domain includes residues 1-363 and the second-domain includes residue 364 to the end. There is approximately 60% inter-domain amino acid identity. It is clear that gene-duplication and subsequent fusion occurred in the immediate ancestor of the clams Solen, Corbicula, and Pseudocardium. During substrate binding, it is proposed that AK undergoes a substrate-induced conformational change and that the hydrogen bond between D(62) and R(193) stabilizes the substrate-bound structure. However, in Solen and Corbicula two-domain AKs, D(62) is replaced by a G, and R(193) by A, S, or D. Consequently, the two-domain AKs can not form the stabilizing hydrogen bond. Nevertheless, the enzyme activity of Corbicula AK is comparable to those of other molluscan 40 kDa AKs. We assumed that the substrate-bound structure of the two-domain AK is stabilized not by the hydrogen bond between D(62) and R(193) but by the bond between H(60) and D(197), characteristic of the unusual two-domain AKs. This explains why D(62) and R(193), which remain highly conserved in other AKs, have undergone amino acid replacements in Solen and Corbicula AKs.     

Satellite telemetry reveals population specific winter ranges of beluga whales in the Bering Sea

At least five populations (stocks) of beluga whales (Delphinapterus leucas) are thought to winter in the Being Sea, including the Bristol Bay, Eastern Bering Sea (Norton Sound), Anadyr, Eastern Chukchi Sea, and Eastern Beaufort Sea (Mackenzie) populations. Belugas from each population have been tagged with satellite‐linked transmitters, allowing us to describe their winter (January–March) distribution. The objectives of this paper were to determine: (1) If each population winters in the Bering Sea, and if so, where? (2) Do populations return to the same area each year (i.e., are wintering areas traditional)? (3) To what extent do the winter ranges of different populations overlap? Tagged belugas from all five populations either remained in, or moved into, the Bering Sea and spent the winter there. Each population wintered in a different part of the Bering Sea and populations with multiple years of data (four of five) returned to the same regions in multiple years. When data were available from two populations that overlapped in the same year, they did not occupy the shared area at the same time. Although our sample sizes were small, the evidence suggests belugas from different populations have traditional winter ranges that are mostly exclusive to each population.     

Two trichodinid ectoparasites from marine molluscs in the Yellow Sea,off China,with the description of <Emphasis Type="Italic">Trichodina caecellae</Emphasis> n. sp. (Protozoa: Ciliophora: Peritrichia)

The morphology and infraciliature of two ectoparasitic ciliates, Trichodina caecellae n. sp. and T. ruditapicis Xu, Song & Warren, 2000, parasitising the gills of marine molluscs from the Shandong coast of the Yellow Sea, China, were investigated following wet silver nitrate and protargol impregnation. T. caecellae was found on the small marine sand clam Caecella chinensis Deshayes and is distinguished mainly by the acute triangle-like blade, the very delicate central part and the needle-shaped ray. T. ruditapicis was studied based on four populations from three clams: two populations from Ruditapes philippinarum (Adams) and one each from Saxidomus purpuratus (Sowerby) and Solen grandis Dunker. All four populations fell within the range of morphometry and agreed closely in the overall appearance of the adhesive disc. However, variability was found in the denticle structure, especially in populations from different host clams. Our observations suggest that denticle morphology may be more or less variable between and within populations, and that such minor differences should not be overestimated. It should be emphasised that, except for the denticle morphology, the bright granules or circles in the centre of the adhesive disc represent another important feature facilitating the identification of this trichodinid species.     

Phylogenic and geographic analysis of chum salmon Oncorhynchus keta (Walbaum) in Asian populations based on mitochondrial DNA variation

We used restriction length polymorphism (RFLP) analysis of PCR-amplified fragments of mtDNA to study the genetic structure of chum salmon populations sampled in 1993-2000 during a spawning run in five rivers: Narva (Southern Primorye), Naiba (Sakhalin Island), Sernovodnaya (Kunashir Island, Southern Kuril Islands), Ola (northwestern coast of the Sea of Okhotsk), and Anadyr' (Chukotka Peninsula). In total, 49 haplotypes were identified in 193 fish. Heterogeneity tests showed highly significant (P = 0) differences among all sample pairs. The estimated time of independent divergence of the populations or population groups is in good agreement with the time of Pleistocene glaciations. This result suggests that it is cyclic global changes during this time period that were crucial in determining the within-species divergence in chum salmon. The types of mtDNA genetic variability and mismatch distribution between haplotypes in the populations indicate that the southern regions of the Sea of Okhotsk and Sea of Japan served as refugia for chum salmon during glaciation periods.     

Y-Chromosome Haplotypes in the Greek–Turkish Area

Various populations have contributed to the present-day gene pool in oriental Mediterranean (Aegean Sea) and are well documented for ancient history. The primary objective of the study is to report on the analysis of the paternal component of the variation (Y chromosome haplotypes) in contemporary populations in Greece, Crete, Turkey and Cyprus. A total of 245 males who hailed from five different locations in Turkey, Greece, and the islands of Crete and Cyprus were analyzed for Y-chromosome-specific haplotypes based on p49a,f TaqI polymorphism. The main haplotype observed (21.2%) in the Greek–Turkish area is haplotype VII. The second haplotype in terms of frequency (13.5%) is haplotype VIII, which is characteristic of Semitic populations. The third (11.4%), fourth (6.9%) and fifth (5.7%) haplotypes in frequency are haplotype XI (a typical eastern European haplotype), haplotype V (the North African haplotype) and haplotype XV (the Western European haplotype), respectively. The distribution of haplotype VII is significantly heterogeneous genetically among the five localities studied, with a peak of frequency (43.8%) in Crete. It is proposed that haplotype VII reflects the ancient Minoan civilization. Haplotype VII frequencies actually known are mapped in countries surrounding the Mediterranean Sea.     

Phylogeographic Analysis of Chum Salmon Oncorhynchus keta Walbaum in Asian Populations Based on mtDNA Variation

We used restriction length polymorphism (RFLP) analysis of PCR-amplified fragments of mtDNA to study the genetic structure of chum salmon populations sampled in 1993–2000 during a spawning run in five rivers: Narva (Southern Primorye), Naiba (Sakhalin Island), Sernovodnaya (Kunashir Island, Southern Kuril Islands), Ola (northwestern coast of the Sea of Okhotsk), and Anadyr' (Chukotka Peninsula). In total, 49 haplotypes were identified in 193 fish. Heterogeneity tests showed highly significant (P = 0) differences among all sample pairs. The estimated time of independent divergence of the populations or population groups is in good agreement with the time of Pleistocene glaciations. This result suggests that it is cyclic global changes during this time period that were crucial in determining the within-species divergence in chum salmon. The types of mtDNA genetic variability and mismatch distribution between haplotypes in the populations indicate that the southern regions of the Sea of Okhotsk and Sea of Japan served as refugia for chum salmon during glaciation periods.     

Red king crab (Paralithodes camtschaticus) in the Barents Sea: a comparative study of introduced and native populations

Red king crab (Paralithodes camtschaticus) was introduced into the Barents Sea in the 1960-1970s. Its present habitation area spans on the coastal zone from Hammerfest (Northern Norway) to the Barents Sea Funnel in the north-east of the Kola Peninsula. We studied the polymorphism of a mitochondrial gene encoding cytochrome oxidase (COI) and five nuclear microsatellite loci in four samples from the Barents Sea and two donor populations from the Western Kamchatka and Primorye. No decrease in the genetic diversity of the introduced populations was detected. Microsatellite assay demonstrated that the sample from Varrangerfjord was distinct from the rest five populations. However, no significant differences between the rest samples were found. Possible reasons underlying this phenomenon are discussed.     

Evidence for Two Highly Differentiated Herring Groups at Goose Bank in the Barents Sea and the Genetic Relationship to Pacific Herring, Clupea pallasi

Genetic studies on Atlantic herring, Clupea harengus, have generally revealed a low level of genetic variation over large geographic areas. Genetically distinct herring populations in some of the Norwegian fjords are exceptions, and juvenile herring from the large oceanic herring, Norwegian Spring Spawners (NSS), are often found in mixture with local fjord populations as well as widely distributed in the Barents Sea. Research surveys in the eastern Barents Sea (Goose Bank) in 1993, 1994 and 2001 included collection of herring samples for allozyme analyses. As expected the results identified juveniles from NSS stock, but an additional unique group of herring (low vertebrae number), being almost fixed for alternative alleles at several allozyme loci, was detected. In some cases, the two groups of herring were taken in the same trawl catches as documented by highly significant departure from Hardy—Weinberg expectation with large excess of homozygotes providing evidence for population mixing. Large genetic differences (Nei's genetic distance = 1.53; F_ST = 0.754) were detected in pairwise comparisons based on five allozyme loci. The two herring groups were also compared with reference samples of Pacific herring, Clupea pallasi, including one sample from Japan Sea and three Alaskan samples. UPGMA dendrogram based on five allozyme loci revealed a close genetic relationship between the low vertebrae herring in the Barents Sea and the group of samples of Pacific herring. Although significant different in allele frequencies, one of the herring samples clustered together with the reference sample from Bering Sea with genetic distance of 0.008 and F_ST value of 0.032. The close genetic relationship found in this paper, suggest a re-evaluation of the taxonomic status of the Barents Sea herring populations investigated.     

Molecular identification of Ammodytes (PISCES, Ammodytidae) larvae, with ontogenetic evidence on separating populations

A total of ten larval Ammodytes were collected from the Yellow (5 specimens) and Bering Seas (5), and a 638 base pair sequence from their mitochondrial DNA COI genes was analyzed for species identification. Sequences were compared with those of adult Ammodytes personatus from the East (4), the Yellow (2) and the East China Seas (2), and Japan (3). Average genetic distance was 0.064 between the Yellow Sea larvae and the Bering Sea larvae, but was 0.0043 between the Yellow Sea larvae and all the adult A. personatus except two individuals from the East Sea. NJ-tree showed that five Yellow Sea larvae were closely clustered with adult A. personatus, except for two individuals. The five Bering Sea larvae were located distantly from adult A. personatus, and are thought to be A. hexapterus. We found morphological differences among two populations of A. personatus larvae and A. hexapterus larvae in morphometric characters and pigmentation. Our results indicated that the East Sea population of A. personatus is closer to A. hexapterus than to the Yellow Sea population of A. personatus, suggesting the East Sea population may be part of separate species.