宽翅曲背蝗两个地理种群等位酶的比较

采用水平淀粉凝胶电泳技术及应用等位酶分析方法,研究我国河北黄骅、辽宁葫芦岛宽翅曲背蝗两个自然种群的遗传多样性和遗传分化。在检测的11种酶15个酶基因座位中,Adk-I、Fbp-I、Mdh-2和G3pd-I基因座位的等位基因少,而Fbp-2、Mdh-I和Me-I基因座位的等位基因多。对每个基因座位的各基因型进行χ^2检验,除Mdh-I在辽宁葫芦岛种群、Adk-I在河北黄骅种群分别符合Hardy-Weinberg平衡外,其余绝大多数基因座位的基因型频率显著偏离Hardy-Weinberg平衡。两个种群之间存在明显的遗传多样性和分化：多态位点百分率分别为100％和93．3％,等位基因平均数分别为3．1和2．5,平均杂合度观测值分别为0．086和0．061。与其他非迁飞性蝗虫如中华稻蝗(Oxya chinensis)比较,这种蝗虫种群的平均杂合度较低但遗传多态性较高。结果表明：该蝗虫较强的跳跃能力可使个体暴露于各种不同环境,有利于维持种内遗传多态性的动态平衡,而种群保持较高的遗传多态性能增强该物种在不同栖息地的生存和繁殖能力。F-统计量表明两个种群之间的遗传分化相对较小,但这种分化显著高于迁飞性蝗虫如东亚飞蝗(Locusta migratoria manilensis)。Nei的遗传一致度(I)和Roger的遗传距离(D)的结果分析揭示了两个种群之间较高的遗传一致度(I=0．904)和较小的遗传距离(D=0．256)。然而,在一些酶基因座位如Aep-I(Fst=0．462)和Pgi-I(Fst=0．182),F-统计值相对较大,遗传分化比较明显。     

中国东亚飞蝗四个地理种群遗传结构的比较研究

利用水平切片淀粉凝胶电泳技术,分析了不同蝗区东亚飞蝗四个地理种群的遗传结构。在检测的20个酶基因座位中,四个种群均表现出一定的遗传多态性, 多态位点的百分率普遍偏高 (P=70%～80%),但由于杂合子数目较少而使每个位点的平均杂合度观察值偏低(H_o=0.023～0.032)。对每个基因座位的各基因型进行χ²检验, 除 Adk-1、Gdh-1、G3pd-1和Pgm-1在部分种群符合Hardy-Weinberg平衡外,其余绝大多数基因座位的基因型频率显著偏离Hardy-Weinberg平衡。从F统计量看,四个种群之间的遗传分化较低(F_st=0.0606 )。它表明： 东亚飞蝗较强的长距离迁飞行为增加了种群之间的基因交流, 降低了种群之间的遗传分化。根据Nei的遗传一致度（I）和Roger的遗传距离（D）进行分析, 在山西临猗与山西永济(I=0.964, D=0.175)、河南中牟与江苏沛县种群(I=0.957, D=0.160)之间,呈现出较高的遗传一致度和较小的遗传距离。结果表明： 迁飞性蝗虫东亚飞蝗种群之间的遗传分化与地理距离呈正相关。     

黄河下游家绵羊与家山羊遗传关系的微卫星分析

为了探讨家养绵羊与山羊的属间遗传关系,我们利用13个定位于绵羊染色体上的微卫星基因座,分析了黄河下游4个地方绵羊品种、4个地方山羊品种和1个杂交绵羊类群的遗传结构及其系统发生关系.经Hardy-Weinberg平衡检验和中性测试,发现地方绵羊和山羊种群均处于不平衡状态(P＜0.01),61.53%的基因座属于中性位点,说明所研究种群属于非随机交配,可能受到选择、迁移等进化因素的影响.对有效等位基因数、多态信息含量、Shannon信息指数、观察杂合度和期望杂合度等遗传多样性参数进行比较,发现绵羊种群的遗传变异程度明显(P＜0.01或P＜0.05)高于山羊种群,但不同基因座上的差异效应不一致;结合F统计量和亲缘关系等参数,可推测绵羊和山羊虽然均存在不同程度的近交现象(He＞Ho,FIS＞0),但分别属于杂交和近交繁殖.通过群体遗传分化和系统发育拓扑结构分析,证明绵羊属由共同祖先分化而来的时间晚于山羊属,两属间的遗传距离为1.0708-1.5927,遗传分化时间约为19,807-28,955年;绵羊属内品种间的遗传分化程度(FST＜0.05)均低于山羊属内品种间的分化(FST＞0.15).本研究揭示了人工选择对同域家养绵羊与山羊交配系统的形成及群体遗传分化具有深刻的影响.     

ABO血型的遗传平衡问题解析

人类控制ABO血型的基因座位上的等位基因频率的估计是相当棘手的问题.在遗传学著作、教材和教学中,群体遗传平衡相关估算中常出现"循环论证",这一问题需要深入分析.从根本上讲,ABO血型遗传平衡估算问题的困难来自2个等位基因对第3个的完全显性.在实际中.人类大群体中的ABO血型一般是平衡的,因此可用r=(-O)1/2、q=1-((-A) (-O))1/2和p=1-((-B) (-O))1/2近似地求基因频率.     

实验兔三个封闭群微卫星DNA多态性遗传分析

目的 对日本大耳白兔、青紫蓝兔、新西兰兔三个封闭群体开展群体遗传学分析.方法 利用10个微卫星位点,进行Hardy-Weinberg平衡(HWE)检验,统计三个种群的基因频率、观测杂合度、期望杂合度、F值和遗传距离.结果 青紫蓝品种在12L1E11位点,新西兰品种在INRACCDDV0087位点与INRACCDDV0203位点,日本大耳白兔在Sat12位点与INRACCDDV0203,P＜0.05,显著偏离HWE,多数表现为杂合子缺陷;三个群体在Sat13、So144、6L1F10、7L1F1、12L4A1、INRACCDDV0016点上均符合HWE;各位点平均等位基因数5.9,种群整体基因频率差别较大,其范围为0 -0.9060;三个种群的平均观测杂合度为0.6204,平均期望杂合度为0.6178;群体间分化系数(Fst)平均为0.0750,日本大耳白兔和青紫蓝兔遗传距离最近为0.1223,青紫蓝兔与新西兰兔遗传距离最远为0.1934.结论 三个种群的遗传结构均表现出遗传稳定性和均一性,在10个微卫星位点上呈现高度多态性,种群间遗传分化明显.     

山西省8种蝗虫8个种群的遗传学研究

采用水平淀粉凝胶电泳技术,对采自山西省蝗虫区系的优势种类;斑腿蝗科（Catantopidae）,斑翅蝗科（Oe-dipodidae）和网翅蝗科（Arcypteridae）3科7属8种蝗虫的11种酶进行了检测,共辨析出17个酶基因座位,并计算出等位基因频率和遗传距离,等位基因频率分析表明：Ao-I、Est-3,G3pd-1、Idh-2和Mdh-2基因座位的等位基因少,等位基因数目在种间变化较小,故推断其进化速率较慢,利用这些基因座位的保守特征,可作为分子标记研究较高级阶元的系统发育关系,而Gpi-1,Ldh-1和Me-1基因座位的等位基因多,等位基因数目在种内和种间差异较大,可以用作种,属间及种群间遗传结构的比较研究。对每个基因座位的各基因型进行χ^2检验,除Acp-1,Adk-1,Ao-1和Ao-2在部分蝗虫中符合Hardy-Weinberg平衡外,其余绝大多数基因座位的基因型频率显著偏离H-W平衡。在所研究的8种蝗虫中,多态位点百分率普遍较高（P=64.7%～94.1%）,但由于杂合子数目较少而使每个基因座位的平均杂合度降低（Ho=0.024～0.087）,对多态位点百分率分析发现：迁飞能力是影响蝗虫种间遗传变异的因素之一,具有迁飞能力的蝗虫（P=88.2%～94.1%）较非迁飞性蝗虫（P=64.7%～94.1%）表现出较高的遗传多态性,但也有例外,如中华稻蝗（Oxya chinensis）的P值高达94.1%,上述结果表明：由于迁飞行为可使个体暴露于各种不同环境,故而种群保持较高的遗传多态性能增强该物种在不同栖息地的生存和繁殖能力,因此,迁飞有利于维持迁飞性蝗虫遗传多态性的动态平衡。根据Nei的遗传一致度（I）和Roger的遗传距离（D）进行分析,结果与基于形态特征确定的分类阶元系统关系基本相符;即同属的小翅雏蝗（Chorthippus fallax）和白纹雏蝗（Chorthippus albonemus）具有最高的遗传一致度（I=0.813）和最小的遗传距离（D=0.336）,同位不同属间遗传一致度（I=0.798～0.559）和遗传距离（D=0.398～0.474）居中,科之间I值最小（I=0.523～0.479）,D值最大（D=0.505～0.523）,利用UPGMA对I值和D值进行聚类,所得两种聚类图在同属种间和同科属间的关系一致,但在科间关系有所差别,Roger的遗传距离（D）聚类树图表明：斑腿蝗科物种和斑翅蝗科物种间表现出较小的遗传距离（D=0.505）,而网翅蝗科与以上两科的遗传距离也极为接近（D=0.523）,综上所述,等位酶分析能较好地反映蝗虫同属种间和同科属间的亲缘关系,若能断更高阶元的系统发生,则需结合其他性状进行综合分析。     

山西省六个负蝗种群的遗传多样性

用等位酶电泳分析方法对短额负蝗(A tractom orpha sinensis)和奇异负蝗(A tractom orpha p ereg rina)各3个自然种群10种酶(AAT,CK,G 3PD,HEX,IDH,LDH,M DH,M E,PG I,PGM)进行检测。结果显示:两种负蝗在某些基因座上共享常见的等位基因,如A a t-1-b、A a t-2-b、G 3p d-a、Ck-1-b和Ldh-b;除个别基因座在部分种群符合H ardy-W e inberg平衡外,两种负蝗的大多数基因座的基因型频率显著偏离H ardy-W e inberg平衡。此外,奇异负蝗M e-c(0.318~0.740)、短额负蝗H ex-1-a(0.800~1.000)及Ldh-b(0.487~0.750)等位基因频率呈现出由北向南递增的趋势,表明M e和H ex、Ldh基因座上的等位基因频率与地理分布存在一定的相关关系。短额负蝗平均每个基因座的等位基因数(A)为1.9~2.3、多态基因座百分率(P)为56.3%~68.8%、平均观察杂合度(Ho)为0.072~0.096;而奇异负蝗的相应值依次为A=1.7~2.2,P=43.8~56.3%,Ho=0.070~0.107。从A、P和Ho3个参数可知,短额负蝗遗传多样性明显高于奇异负蝗。6个负蝗种群的平均观察杂合度均明显低于H ardy-W e inberg平衡预期值,表明6个负蝗种群均出现了杂合体缺乏现象。短额负蝗3种群I值为0.971~0.996,奇异负蝗3种群I值为0.982~0.995,短额负蝗与奇异负蝗I值为0.379~0.451,表明种内遗传相似度明显高于种间,从种间I值可知奇异负蝗和短额负蝗属于近缘种。根据R oger's遗传距离进行的聚类分析表明,两种负蝗可分为两支,且两种负蝗的遗传距离与地理距离均存在明显的相关趋势。两种负蝗的平均FST值都不显著偏离0值(奇异负蝗FST=0.087,p>0.05,短额负蝗FST=0.045,p>0.05),表明该两种负蝗种群间的分化不明显。     

华北2蝗区东亚飞蝗种群遗传结构的比较研究

利用水平淀粉凝胶电泳对采自天津北大港和河北黄骅两个相临蝗区的东亚飞蝗（Locusta migratoria manilensis)种群进行等位酶基因频率分析,比较了这两个种群的遗传结构,等位酶酶谱分析表明,19个基因座中4个基因座（Mdh-l,Pgm,Adk,G3pd)的等位基因频率变化很小,常见等位基因的频率均高于0．95,其他基因座有2－4个等位基因,但是两个种群的等位基因频率除两个基因座（Fbp,Got-2)外都很相似,多态位点的27个χ2检验表明,由于常见等位基因纯合子的高频率的和相应杂合子的缺乏,仅有北大港种群的2个基因座（Pgi,Got-1)符合Hardy-Weinberg平衡,在每个种群内的蝗虫存在明显的遗传变异,但在种群间遗传结构极为相似,多态位点的百分数P分别为73．7％和78．9％,每个基因座的平均等位基因数A为2．9和3．1,平均每个基因座的实际杂合度几乎相等（约为0．138）,F－统计量（FST＝0．053）也表明了两个种群间的遗传 一致性,遗传相似性系数（I）高达0．938,这些结果提示,这两个种群可能属于1 个大种群,在两个种群的一定位点上的遗传多态性和分化可能都与迁飞因素有关,因为东亚飞蝗的高度扩散能力有利于遗传结构的连续分布,高度的迁飞能力也导致个体暴露于各种不同的环境,而在种群水平上的遗传为异能增强种群在各种生态条件生存和繁殖能力,因此,迁飞有利于维持东亚飞蝗种群的遗传多态性的动态平衡。     

SSR 在琼海和三亚两普通野生稻居群中的遗传变异

通过分析37个SSR座位在琼海与三亚两普通野生稻(Oryza rufipogon)居群中的遗传变异, 结果表明, SSR座位在三亚普通野生稻居群中的变异高于其在琼海普通野生稻居群中的变异。根据遗传相似性和遗传距离公式得到琼海与三亚普通野生稻居群间的遗传相似性为0.6385, 遗传距离为0.4486 cM。Wright的FST检验结果表明, 这37个SSR座位在两居群之间存在着中等程度的遗传分化, FST=0.3909。此分化结果主要是由两居群间弱的基因漂移导致的(Nm=0.3895)。     

中国东亚飞蝗两个种群遗传分化的研究

采用水平淀粉凝胶电泳技术,分析了我国河北平山、辽宁葫芦岛两个蝗区东亚飞蝗自然种群的遗传结构。在酶谱分析的19个位点中,多数位点的等位基因数目较少,而位点Aat—l、Pgi和Mdh—2的等位基因数目相对较多。由于杂合子数目较少而使每个基因位点的平均杂合度降低(Ho=0．024和0．028)。对每个位点的各基因型进行x^2检验,绝大多数位点的基因型频率偏离Hardy—Weinberg平衡。较低的Fst值(Fst=0．021)表明两个种群的遗传分化程度不高。两个种群间较高的遗传一致度(I=0．991)和较小的遗传距离(D=0．092)也证实了上述结果。由此推测,该蝗虫较强的迁飞能力有可能增强种群间的基因交流,降低种群间的遗传分化。然而,在一些等位酶指标如位点Ao-2、Fbp—l、Mdh—2的等位基因频率分布、每个位点的平均等位基因数(A=2．5和2．7)和多态位点百分率(P=52．6％和57．9％)等,两个种群之间呈现出明显的差异。这也许与两个种群之间不同的生态环境条件和较远的地理距离有关。     

Genetic diversity of six populations of Atractomorpha sinensis and Atractomorpha peregrina in Shanxi Province, China

Ten enzymes (AAT,CK,G3PDH,HEX,IDH,LDH,MDH,ME,PGI,PGM)were examined using horizontal starch gel electrophoresis to estimate the levels of genetic variation within and among six natural populations of two grasshopper species Atractomorpha sinensis and A.peregrina from Shanxi,China.The collecting sites were geographically distant from each other from south to north:Quwo district,Linfen city;Xiangyuan county,Changzhi;Jinyuan district,Taiyuan city;Yuanping county,Xinzhou city and Fanshi county of Xinzhou.A.sinensis showed 43 alleles at 16 loci but A.peregrine showed 39 alleles at 15 loci (ldh-1 was deficient).The zymograms showed that some common alleles were shared at several loci in these two species (Aat-1-b,Aat-2-b,G3pdh-a,Ck-1-b and Ldh-b).However,Hex-1-a,Hex-2-a,Hex-3-a,Idh-2-b,Mdh-2-b,Mdh-1-f Pgi-b,Pgm-b had common alleles in A.sinensis and Hex-1-b,Hex-2-b,Hex-3-b,Idh-2-a,Mdh-2-a,Mdh-1-d,Pgi-a,Pgm-c were of high frequency in A.peregrine instead.Most of the observed genotype frequencies were found to significantly deviate from the Hardy-Weinberg expectations in both species.A tendency of clinal distribution of allele frequency was observed at three loci.The frequency of the moderately migrating allele Me-c (0.318-0.740)in A.peregrina,Hex-1-a (0.800-1.000)and Ldh-b (0.487-0.750)in A.sinensis demonstrated increased frequency from north to south.Such tendency suggests that the allele frequency in these three loci may be correlated with the species'geographic distributions.A.sinensis showed higher genetic diversity than A.peregrina as indicated by higher mean number of alleles per locus (A=1.9-2.3 in A.sinensis and 1.7-2.2 in A.peregrina),percentage of polymorphic loci (56.3%-68.8%in A.sinensis and 43.8%-56.3%in A.peregrina),and the observed heterozygosities (Ho=0.072-0.096 in A.sinensis and 0.070-0.107 in A.peregrina).The observed heterozygosities of the six populations were all noticeably lower than the Hardy-Weinberg expectations,mostly due to heterozygote deficiency in the populations of both species.The overall mean Fsr were small (FST=0.045,P＞0.05 in A.sinensis populations and 0.087,P＞0.05 in A.peregrina populations).Nei's genetic identity (I)estimates indicate low intraspecific (＞0.95)but higher interspecific (0.377-0.447)genetic diversity.The cluster analysis based on modified Roger's genetic distance (D)showed that the two species were divided into two branches.Both species are of limited dispersal capacity and a moderate geographical barrier might significantly restrict the gene exchange among populations,resulting in accumulation of local genetic differentiations.The A.sinensis populations used in this study were separated from each other by 155.2 to 271.4 km and the A.peregrina populations were separated from each other by 78.8 to 174.9 km with observable physical barriers.The aUozyme data showed only minimal genetic differentiation at population level,most likely as a result of gene exchange.It is reasoned that natural factors and human agricultural activities might have facilitated migration and dispersal for the two species.     

Genetic structure of Halotydeus destructor and Penthaleus major populations in Victoria (Acari: Penthaleidae)

The redlegged earth mite (Halotydeus destructor) and the blue oat mite (Penthaleus major) are major pests of pastures and crops in southern Australia. Reproductive modes, migration rates and levels of differentiation between populations were investigated using allozyme electrophoresis. Collections were made throughout Victoria and a sample was also obtained from Western Australia. Three enzyme loci were polymorphic in H. destructor (Mdh-1, Mdh-2 and Idh). Genotype frequencies of these loci did not differ between phenotypic males and females, providing no evidence for haplodiploidy. Allele frequencies were in Hardy-Weinberg equilibrium, indicating that H. destructor is diploid and sexual. This was confirmed via crosses between males and females. Allele frequencies differed between Victorian sites, although F statistics indicated little differentiation over all loci. A sample from Western Australia did not differ in allele frequencies from the Victorian sites. Four polymorphic loci were found in P. major (Mdh-1, Mdh-2, Idh and Gpi). Only a few multilocus genotypes occurred in a sample, indicating that P. major is parthenogenic. No male P. major were found in this study. A number of colour morphs were also identified and a genetic association between genital plate colour and clonal type was found in one population of P. major. Two different body colour morphs were associated with different clonal types.     

Inheritance of Allozyme Loci in Bombina: Second Linkage Group Established

Segregation and linkage relationship of nine allozyme loci, which are fixed for alternative alleles in the European fire-bellied toads, Bombina bombina and B. variegata,were studied using artificial F₁ hybrids to obtain backcross and F₂ progeny. Alleles coding for electromorphs at nine loci (Ldh-1, Mdh-1, Idh-1, Ck, Ak, Gpi, Aat-1, Np, and G6pd)showed Mendelian ratios. Two of the loci, Ak and G6pd, were found to be closely linked (2 cM apart); the other loci assorted independently.     

Isoenzyme variation in Aedes aegypti correlated with Dirofilaria immitis infectability

From the Vero Beach strain of the mosquito Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae), substrains were selected for susceptibility (SS) and refractoriness (RR) to the dog heartworm Dirofilaria immitis (Leidy) (Filarioidea: Onchocercidae). These two lines and their reciprocal F1 hybrids were analysed for genetic variation at 14 enzyme loci, using polyacrylamide gel electrophoresis. Six of the enzyme loci showed variation (sample size 48 alleles/locus/line). Three of these were monomorphic in the refractory line but polymorphic in the susceptible, i.e. aconitase hydratase (Acoh), isocitrate dehydrogenase-1 (Idh-1) and phosphoglucomutase (Pgm). The other three loci, glucose-6-phosphate isomerase (Gpi), hexokinase-1 (Hk-1) and isocitrate dehydrogenase-2 (Idh-2), were polymorphic in both SS and RR lines and their hybrids. At two loci (Hk-1, Pgm) three alleles were detected, whereas the other polymorphic loci had only two alleles. For Hk-1, the most frequent allele was Hk-1(80) (0.563) in refractory and Hk-1(100) in the susceptible (0.521) and F1 hybrids. For Pgm the most frequent alleles were Pgm125 in the susceptible line (0.646) and Pgm100 in the F1 hybrids (0.563 and 0.604) and refractory line (1.000). The mean observed heterozygosity (Ho), the mean Hardy-Weinberg expected heterozygosity (He) and the mean number of alleles per locus in the refractory line were lower, but not significantly so, than in the susceptible line and their reciprocal F1 hybrids; the proportion of polymorphic loci was significantly lower in the refractory than in the susceptible line and their F1 hybrids. Within both lines all polymorphisms were in Hardy-Weinberg equilibrium, whereas significant departures from predicted frequencies were observed in SS x RR hybrids at four polymorphic loci (Acoh, Gpi, Hk-1, Pgm) and at three polymorphic loci (Acoh, Hk-1, Pgm) in RR x SS hybrids. The average Nei's and modified Rogers' genetic distances between the lines were 0.024 and 0.139, respectively. These electrophoretic data show that the refractory line (putatively lacking fi allele) can be distinguished from the susceptible line (fi/fi) and their hybrids (heterozygous fi) by isozyme marker frequencies, but it remains to be seen whether this difference is causal or chance linkage. In any case, this model system of Ae. aegypti/D. immitis provides opportunities to better understand and manipulate the molecular biology of filariasis transmission.     

Genetic diversity in Cucumis sativus L. assessed by variation at 18 allozyme coding loci

Summary The genetic diversity of the U.S. Cucumis sativus L. germplasm collection [757 plant introductions (PI) representing 45 countries] was assessed using 40 enzymes which represented 74 biochemical loci. Polymorphisms were observed at 18 loci (G2dh-1, Gpi-1, Gpi-2, Gr-1, Gr-2, Idh, Mdh-1, Mdh-2, Mdh-3, Mpi-2, Pepla-2, Peppap-2, Per-4, Pgd-1, Pgd-2, Pgm-1, Pgm-3, and Skdh). Two PIs (285606 and 215589) contained alleles [G2dh-1(1) and Per-4(2), respectively] which did not occur in any other PI. Other alleles which occurred in low frequencies (in < 1% of the PIs) included Gpi-1(3), Gpi-2(3), Gr-1(3), Gr-2(1), Idh(1), Mdh-1(2), Mdh-2(1), Peppap-2(1), and Pgd-1(1). Individual loci containing more than one allele in greater than 20% of the PIs included Mpi-2, Pepla-2, Pgd-2, and Pgm-1. Multivariate analyses aided in the reduction of data (principle components), depicted relationships among PIs (cluster), and identified the most discriminating enzyme loci (Pgm-1, Pepla-2, Gr-1, Pgd-2, Mpi-2, and Skdh) (classification and regression tree).Research partially supported by Asgrow, DeRuiter, Nickerson-Zwaan, Nunhems, and Sun Seed Companies; and the Graduate School, University of Wisconsin, Madison     

Gene flow analysis demonstrates that Phytophthora fragariae var. rubi constitutes a distinct species, Phytophthora rubi comb. nov

Isozyme analysis and cytochrome oxidase sequences were used to examine whether differentiation of P. fragariae var. fragariae and P. fragariae var. rubi at the variety level is justified. In isozyme studies six strains of both P. fragariae varieties were analyzed with malate dehydrogenase (MDH), glucose phosphate isomerase (GPI), aconitase (ACO), isocitrate dehydrogenase (IDH) and phosphogluconate dehydrogenase (PGD), comprising altogether seven putative loci. Five unique alleles (Mdh-1(A), Mdh-2(B), Gpi(A), Aco(B) and Idh-1(B)) were found in strains of P. fragariae var. fragariae, whereas five unique alleles (Mdh-1(B), Mdh-2(A), Gpi(B), Aco(A) and Idh-1(A)) were present in strains of P. fragariae var. rubi. It was inferred from these data that there is no gene flow between the two P. fragariae varieties. Cytochrome oxidase I (Cox I) sequences showed consistent differences at 15 positions between strains of Fragaria and Rubus respectively. Based on isozyme data, cytochrome oxidase I sequences, and previously published differences in restyriction enzyme patterns of mitochondrial DNA, sequences of nuclear and mitochondrial genes, AFLP patterns and pathogenicity, it was concluded that both specific pathogenic varieties of P. fragariae are reproductively isolated and constitute a distinct species. Consequently strains isolated from Rubus idaeus are assigned to Phytophthora rubi comb. nov.     

猕猴桃属植物的cpSSR遗传多样性及其同域分布物种的杂交渐渗与同塑

同域分布的近缘物种常常发生杂交而导致种间基因渐渗, 从而对相关物种的自然居群遗传结构产生重要影响, 近缘种间的杂交渐渗已成为进化生物学和保护生物学关注的热点。本研究采用8对cpSSR引物对我国西部高原台地向中东部丘陵平原过渡地带同域重叠分布的猕猴桃属(Actinidia)7个物种的自然居群遗传多样性、居群遗传结构和同域分布种间遗传分化进行了检测。结果表明: (1)在6个多态性位点检测到18个等位基因形成的42个单倍型, 尽管各单倍型间显示了复杂的网状进化关系, 但还是具有明显的物种特异性; (2)各物种有丰富的cpSSR遗传多样性, 但种间存在较大差异, 绵毛猕猴桃(Actinidia fulvicoma var. lanata)的遗传多样性水平最高(P = 62.50%, h_T = 0.173, H_T = 0.897), 美味猕猴桃(A. deliciosa)的最低(P = 37.5％, h_T = 0.041, H_T = 0.516); (3)尽管不同物种的居群分化程度存在较大差异, 但种内居群间存在明显分化(G_ST为0.319–0.780, F_ST为0.401–0.695), 居群间的基因流不足(N_m为0.219–0.747<1); 其中以美味猕猴桃的居群遗传分化度最高(G_ST = 0.780, F_ST = 0.695); (4)遗传分化系数G_ST(unordered alleles)与N_ST(ordered alleles)无显著差异, 揭示本研究的大多数猕猴桃属物种不存在系统地理结构, 与用Mantel检验得出的居群遗传距离和地理距离不存在显著性相关的结果一致; (5)除了中华/美味猕猴桃复合体(A. chinensis / A. deliciosa complex)的湖北五峰(HW)和广西资源(GZ)两个同域复合居群外, 同域分布的物种间遗传分化强烈(F_ST为0.476–0.990), 与UPGMA聚类时多数居群按各自物种聚类的结果一致。进一步分析表明, 中华/美味猕猴桃复合体近缘种间存在明显的共祖多态性和杂交渐渗现象, 近缘种植株分布的交错程度以及是否存在亚居群结构对杂交渐渗存在着重要影响。亲缘关系较远的物种间杂交渐渗事件稀少, 但存在个别同塑事件。本研究结果有助于进一步了解猕猴桃属植物自然居群cpDNA的遗传特性和渐渗杂交进化模式, 为我国猕猴桃野生种质资源保育及可持续开发利用提供基础数据和科学依据。     

云南松居群遗传学研究的等位酶分析方法

针对１５个云南松Ｐｉｎｕｓｙｕｎｎａｎｅｎｓｉｓ居群,开展了１４种酶系统的水平切片淀粉凝胶电泳实验,在谱带遗传分析的基础上确定了３３个等位酶位点及其等位基因。其中有３２个等位酶位点是多态的（有２个以上的等位基因）,只有一个单态位点Ｄｉａ－４。有３个等位基因的位点有Ｌａｐ－１、Ｌａｐ－２、Ａａ－３、Ｓｋｄ－１、Ｓｋｄ－２、Ａｄｈ－１、Ａｄｈ－３、Ｇｄｈ、Ｐｇｄ－１、Ｐｇｍ－１、Ｐｇｍ－３、Ｐｇｉ－１、Ｐｇｉ－３、Ｍｄｈ－１、Ｍｅ、Ｇ６ｐｄ、Ｄｉａ－１、Ｔｐｉ－１、Ｔｐｉ－２、Ｔｐｉ－３和Ｔｐｉ－４,有４个等位基因的位点有Ｓｋｄ－３、Ａｄｈ－２、Ｐｇｄ－２、Ｍｄｈ－２、Ｍｄｈ－３、Ｍｄｈ－４和Ｄｉａ－２,有５个等位基因的位点有Ａａｔ－１和Ｄｉａ－３。云南松居群的等位基因平均数Ａ＝２１,在松属中居于中上水平。本研究揭示了云南松居群酶位点及其等位基因带谱的变异式样,为松属植物的遗传多样性研究提供了一批酶位点及其等位基因的参考图谱     

Macrogeographic population structure of the tsetse fly, Glossina pallidipes (Diptera: Glossinidae)

Tsetse flies are confined to sub-Saharan Africa where they occupy discontinuous habitats. In anticipation of area-wide control programmes, estimates of gene flow among tsetse populations are necessary. Genetic diversities were partitioned at eight microsatellite loci and five mitochondrial loci in 21 Glossina pallidipes Austin populations. At microsatellite loci, Nei's unbiased gene diversity averaged over loci was 0.659 and the total number of alleles was 214, only four of which were shared among all populations. The mean number of alleles per locus was 26.8. Random mating was observed within but not among populations (fixation index FST=0.18) and 81% of the genetic variance was within populations. Thirty-nine mitochondrial variants were detected. Mitochondrial diversities in populations varied from 0 to 0.85 and averaged 0.42, and FST=0.51. High levels of genetic differentiation were characteristic, extending even to subpopulations separated by tens and hundreds of kilometres, and indicating low rates of gene flow.     

海带(Laminaria japonica)丝状体遗传多样性的比较研究

采用垂直板式聚丙烯酰胺凝胶电泳技术对分别来自中国青岛与日本北海道海带(Laminaria japonica)丝状体的6种酶系统（乙醇脱氢酶、谷氨酸脱氢酶、异柠檬酸脱氢酶、乳酸脱氢酶、山梨醇脱氢酶和超氧化物歧化酶）进行了检测,发现存在22个基因位点,分析了不同来源海带丝状体的遗传多样性与遗传分化程度。结果表明：日本北海道海带丝状体的预期杂合度、每个位点有效等位基因数等遗传参数均大于中国青岛海带丝状体。对日本北海道海带丝状体与中国青岛海带丝状体的遗传相似系数和遗传距离进行了计算分析,显示两者发生了遗传分化。日本北海道海带丝状体的遗传多样性高于中国青岛海带丝状体。研究结果还发现在中国青岛海带丝状体的Idh、Ldh 和Sdh中,以及日本北海道海带丝状体的Adh、Gdh、Idh、Ldh、Sdh和Sod中存在着不同迁移率的不等距双带酶,可能由特殊基因控制,并集中在第3个基因位点上。