中国菜粉蝶线粒体基因组遗传多样性分析

菜粉蝶Pieris rapae是十字花科蔬菜重要的农业害虫。为了深入了解中国菜粉蝶的群体遗传特征,通过高通量测序获取了中国5个群体48头菜粉蝶的线粒体全基因组,并分析了不同群体间的遗传结构与多样性。结果表明：菜粉蝶群体间有较高的线粒体单倍型多样性;相对封闭的山区和盆地地区的核苷酸多样性较低;群体间的平均遗传分化指数（FST）仅0.042,表明不同群体间的遗传分化水平较低,这也暗示了群体间基因交流频繁,推测这与甘蓝等蔬菜频繁运输有关;线粒体进化树和网络图均未形成明显的地理谱系,南北方群体之间没有明显的遗传结构差异;总群体的Tajima''s D和Fu''s Fs值均为负值,且达到了显著水平,这意味着中国地区的菜粉蝶可能经历过群体扩张事件。     

版纳青海居群的遗传多样性和群体分化

我国龙脑香料特有种版纳青海（Vatica guangxiensis）仅局限分布于滇南（勐腊）和植西南（那坡）,本文应用“水平切片淀粉凝胶电泳等位酶分析”方法,对其进行了遗传多样性和群体分化的研究。对14个酶系统23个等位酶点的研究表明,其居群变异水平很低,多态位点比率P为13．0％－21．7％,等位基因平均数A为1．1－1．2,平均期望杂合度0．056－0．130,平均观察杂合度H为0．055－0．130。F统计分析表明版纳青梅具有较高水平的群体分化,基因分化系数高达CST＝0．265。这与其居群内存在一定程度的近交,以及种子的重力散布有关;另外,也可能是在其进化过程中,由于居群的缩小而发生了遗传漂变。此外,本研究也从等位酶水平为广西青梅（V．guangxiensis)和版纳青梅（V．sishuangbannaensis）的合并作一佐证。     

花生根瘤菌群体遗传多样性和系统发育研究

利用16S rRNA RFLP,16S rRNA序列分析和16S－23S IGS PCR RFLP技术对43株花生根瘤菌和来自其他种属的15个参比菌株进行了群体遗传多样性和系统分析。16S rRNA PCR RFLP分析结果表明,所有供试花生根瘤菌均属于慢生根瘤菌属,在系统发育上与B.japonicum的亲缘关系最近,具有相同的16S rRNA RFLP基因型,而与B.elkanii相对较远。16S rRNA 序列分析结果表明,供试花生根瘤菌在系统发育上更接近于B.liaoningense,序列间差异小于1％,而B.liaoningense在系统发育上与B.japonicum相距很近,其序列间差异小于1％,16S－23S rRNA IGS RFLP分析结果表明,尽管花生根瘤菌与B.japonicum和B.elkanii的亲缘关系很近,但在71％的相似性水平上供试花生根瘤菌仍各自聚为一群,并可进一步分为A、B、C和D4个亚群,该分群还明显反映了地理因素对群体遗传多样性和系统发育的影响。     

八面山银杉林的遗传多样性和群体分化

采用水平淀粉凝胶电泳技术对分布于湖南八面山的濒危植物银杉(cathaya argyrophylla Chun etKuang)的遗传多样性和群体分化进行了初步研究。对13个酶系统25个等位酶位点的检测表明,该地区的银杉林群体遗传变异水平很低,多态位点比率 P=0.28,等位基因平均数 A=1.36,平均期望杂合度He=0.100;但3个小群体间存在着明显的遗传分化,基因分化系数高达G_ST=0.26,明显不同于其它裸子植物的报道。八面山银杉林低水平的遗传变异和明显的群体分化,一方面反映了银杉的古老性和残遗性,另一方面也说明在银杉的进化过程中可能发生了严重的遗传漂变,而且群体之间的基因流明显受阻。     

版纳青梅居群的遗传多样性和群体分化

我国龙脑香科特有种版纳青梅(Vatica     

2个中国藏獒群体遗传多样性及遗传分化的研究

本研究以青海土种犬和藏狮犬为对照,采用RAPD技术对河曲藏獒和青海藏獒群体的遗传多样性及遗传分化进行了分析.研究结果表明,河曲藏獒和青海藏獒群体的多态性位点百分率分别为85.53%和98.16%,平均多态性位点百分率为91.85%.藏獒群体遗传变异分析显示两个藏獒群体的有效等位基因数(Ne)、Nei氏平均预期基因杂合度(H)和Shannon遗传信息指数(I)的平均值分别为1.5354、0.3191和0.4807;且两个藏獒群体93.09%的变异来自群体内,仅6.91%变异来自群体间;两个群体间的基因流为3.3679.研究还发现两个藏獒群体之间的Nei氏标准遗传距离(D)为0.050 5.本研究结果说明藏獒群体内遗传变异丰富,不同地域的藏獒群体之间存在广泛的基因交流,群体之间遗传分化程度很低,这为藏獒品种资源保护与合理开发利用提供了参考.     

马鹿阿拉善亚种遗传多样性和群体结构

马鹿阿拉善亚种（Cervus elaphus alashanicus）又称阿拉善马鹿,目前仅分布于贺兰山地区,是我国马鹿亚种分布范围最狭窄的一个隔离种群。为了解阿拉善马鹿的种群遗传多样性及遗传变异情况,以对该种群的保护提供科学参考,对在贺兰山采集的93个野生个体新鲜粪便样本的线粒体控制区部分序列（991 bp）进行扩增和分析,共检测到68个变异位点,定义16种单倍型,平均单倍型多样性为0.405,平均核苷酸多样性为0.00232,说明种群遗传多样性水平较低。中性检验和错配分布分析表明阿拉善马鹿曾出现过种群扩张,贝叶斯天际线分析（BSP）显示扩张时间约在末次冰盛期（0.028—0.010 Ma）。FST检验表明阿拉善马鹿种群内存在显著遗传分化,系统发育树和单倍型网络图分析表明群体间没有明显的系统地理格局。本研究表明阿拉善马鹿目前种群遗传多样性较低,建议加大对该亚种的关注和保护力度。       

中国石榴栽培群体遗传多样性的荧光AFLP分析

以中国山东、安徽、陕西、河南、云南和新疆6个栽培石榴群体的85个品种类型为试材,利用荧光标记AFLP对中国石榴群体遗传多样性进行了研究。结果表明：8对引物组合在种级水平扩增的多态性位点数范围从135～185个不等,平均为158.25个,多态位点百分比范围为62.5%～86.11%,平均为73.26%,说明中国石榴品种遗传多样性较为丰富;石榴品种种级水平遗传多样性大于群体水平,6个群体的遗传多样性依次为河南群体〉新疆群体〉陕西群体〉安徽群体〉山东群体〉云南群体,并且具有显著性差异;群体间的遗传分化系数GST为0.2018,说明石榴遗传变异主要存在群体内,群体间的遗传变异占总变异的20.18%,根据基因分化系数,测得的基因流Nm为1.9027,说明中国石榴群体间存在适当的基因交流;UPGMA聚类分析结果表明,同一群体的大部分品种都聚在一起,但同时存在部分基因交流。所有遗传参数表明,中国石榴栽培品种遗传多样性较为丰富,其中河南群体遗传多样性显著高于其他群体,在中国石榴品种选育中具有更为广阔的应用前景。     

华南鲤选育群体不同世代遗传多样性与遗传结构的微卫星分析

为了解人工选育对华南鲤(Cyprinus carpio rubrofuscus)选育群体遗传结构的影响, 采用微卫星技术分析了华南鲤4个连续选育世代(F₁、F₂、F₃和F₄)的遗传多样性和遗传结构。结果显示:在4个选育群体中, 16对微卫星引物共扩增得到99个等位基因, 每个微卫星座位检测到的等位基因数为3—10个, 平均为6.1875个。随着人工连续选育的进行, F₁到F₄的平均等位基因数(N_a)从5.6875下降到4.6755, 平均观测杂合度(H_o)从0.7943下降到0.7135, 平均多态信息含量(PIC)从0.6577下降到0.5834。F₁与其后各代的遗传距离逐代增加(从0.1486上升到0.2181), 遗传相似系数逐代减小(从0.8619下降到0.8041), 而相邻世代间的遗传分化指数(F_st)逐代变小(F₁与F₂为0.062, F₂与F₃为0.058, F₃与F₄则为0.051), 遗传相似性逐步升高。世代间F_st值配对比较结果显示4个世代间的遗传分化处于中等水平, 表明人工选育已对华南鲤选育群体的遗传结构产生了影响。实验结果表明, 华南鲤经过4代选育后, 虽然遗传杂合度和遗传多样性存在下降的现象, 但遗传多样性水平依然较高, 还具有进一步选育的潜力。研究结果为下一步制定华南鲤新品种选育计划提供基础遗传数据。     

The effect of temporal variability in salinity on the invasive red alga Gracilaria vermiculophylla

Non-native, invasive species are often characterized by being tolerant to environmental stressors, leaving them more fit relative to native species. The red alga Gracilaria vermiculophylla originates from the NW Pacific but has recently spread along the coastlines of Western Europe, where it has become abundant in many shallow, soft-bottom estuaries. Salinity is important for the local and regional distribution of algae. The distribution of G. vermiculophylla in Europe suggests that it thrives well in hyposaline environments and that it may be more fit than some native algae under such conditions. Little, however, is known about the ecophysiology of G. vermiculophylla and it is therefore difficult to predict its spread and future distribution. Laboratory experiments with G. vermiculophylla showed that steady-state salinity above 15?psu was optimal for growth and that the growth rate was reduced at salinities below 15?psu. Variable salinity reduced the growth rate and larger oscillations were more stressful than small ones. Exposure to very low salinity (0–5?psu) was stressful for the alga and algae exposed to these low levels for 2–4 days were unable to recover fully. Gracilaria vermiculophylla did not seem to perform better in hyposaline conditions than many native, estuarine species. The present distribution of G. vermiculophylla in Scandinavia can be explained well by its response to salinity, but this may not explain its present success relative to many naturally occurring algal species.     

Flora and fauna associated with the introduced red alga Gracilaria vermiculophylla

This paper presents the first detailed study of the spread of the introduced marine red alga Gracilaria vermiculophylla on the west coast of Sweden, and of the fauna and flora associated with this alga in Scandinavia and the western mid-Atlantic. G. vermiculophylla was discovered in the archipelago of Göteborg, Sweden, in the summer of 2003, and in 2005 its distribution range covered at least 150 km. The species is typically found as loose-lying thalli or attached to small stones and mollusc shells within low-energy bays and estuaries. Both gametophytic and tetrasporophytic specimens were found, as well as specimens with mixed reproductive stages. In order to assess the importance of this introduced alga as a habitat for native benthic organisms, attached and loose-lying individuals of G. vermiculophylla were sampled from invaded locations in Sweden, Denmark and Virginia (United States). In total we found 92 taxa associated with G. vermiculophylla. The dominant classes were Malacostraca, Gastropoda and Florideophyceae. The diversity of the associated taxa was not affected by attachment status, or G. vermiculophylla biomass. In Virginia and Sweden animal abundances were positively correlated with the biomass of algae and plants associated with G. vermiculophylla. If G. vermiculophylla primarily invades non-vegetated soft-sediment estuaries, the invasion may lead to an increase in abundances of small native invertebrates (e.g. gastropods and crustaceans) and epiphytic algae, with likely cascading effects on higher trophic levels.     

中国东南沿海弹涂鱼科常见鱼类的遗传多样性和DNA条形码

为了探究中国东南沿海海岸线经济开发、海水污染等对该区域生物遗传多样性的潜在影响,本文使用COI基因作为DNA条形码,对从中国东南沿海广东汕头、福建东山、福建云霄、福建泉州、福建霞浦、上海崇明6个地点采集的大弹涂鱼(Boleophthalmus pectinirostris)、弹涂鱼(Periophthalmus modestus)和青弹涂鱼(Scartelaos histophorus)进行种间和种内的遗传学分析。遗传多样性分析显示,青弹涂鱼的核苷酸多样性(0.0018)在3个种中最低;青弹涂鱼广东汕头种群的核苷酸多样性(0.0018)比福建云霄种群低;大弹涂鱼的上海崇明种群核苷酸多样性(0.0021)低于其他5个地理种群。物种水平分析表明,3个物种间分化明显,种间与种内遗传距离有明显差异;不同种的单倍型在系统发育树上聚成3个高度支持的独立分支。种群水平分析显示,大弹涂鱼的6个不同地理种群之间有共享单倍型,地理种群间与地理种群内的遗传距离重叠;各地理种群之间的基因流较频繁(Nm>4);青弹涂鱼的分析情况与大弹涂鱼基本一致。大弹涂鱼和青弹涂鱼的单倍型在系统发育树上均呈现多系或并系分布格局,并未按地理位置分成不同的单系群。本研究表明,应及时加强3种鱼类及其野生种群遗传多样性的保护,且COI基因对种一级的识别明确可靠,而在地理种群水平的识别则比较困难,有待进一步深入研究。     

Yield, chemical composition and gel strength of agarocolloids of Gracilaria gracilis, Gracilariopsis longissima and the newly reported Gracilaria cf. vermiculophylla from Roscoff (Brittany, France)

Agarocolloids were extracted from field samples of Gracilaria gracilis, Gracilariopsis longissima and the newly reported Gracilaria cf. vermiculophylla harvested at different periods of the year near Roscoff (France). Native and alkali modified extracts were characterized by GLC, HPLC and FT-IR spectroscopy. The main components of agarocolloids isolated by freeze-thawing method, were 3,6-anhydrogalactose and galactose. In addition, minor components (6-O-methyl-galactose, 4-O-methyl-galactose and sulfate groups ranging from 4.4 up to 6.6% [w/w]) were detected. The highest rate of 6-O-methylgalactose was observed in agarocolloids from vermiculophylla (14 mole%). Sulfates were mainly branched on C4 of the D-galactose in gracilis and Gs. longissima agarocolloids. G. vermiculophylla agaroids isolated by EtOH and NaCl precipitations from the syneresis water were characterized by a high sulfation on C6 of galactose and a low sulfation on C2 of 3,6-anhydrogalactose. Native agarocolloid gel strengths from Gracilaria species were clearly higher than those of Gracilariopsis. Alkali treatments reduced the sulfate levels but increased slightly the gel strengths. An approximation of the polymer sizes carried out with colorimetric assays indicated that the polymer sizes were higher in G. gracilis than observed in Gs. longissima. This revised version was published online in June 2006 with corrections to the Cover Date.     

GENETIC DATA HINT AT A COMMON DONOR REGION FOR INVASIVE ATLANTIC AND PACIFIC POPULATIONS OF GRACILARIA VERMICULOPHYLLA (GRACILARIALES,RHODOPHYTA)1

Gracilaria vermiculophylla (Ohmi) Papenf., an agar‐producing red alga introduced from northeast Asia to Europe and North America, is often highly abundant in invaded areas. To assay its genetic diversity and identify the putative source of invasive populations, we analyzed the mitochondrial cytochrome c oxidase subunit I (cox1) gene from 312 individuals of G. vermiculophylla collected in 37 native and 32 introduced locations. A total of 19 haplotypes were detected: 17 in northeast Asia and three in Europe and eastern and western North America, with only one shared among all regions. The shared haplotype was present in all introduced populations and in ～99% of individuals in the introduced areas. This haplotype was also found at three native locations in east Korea, west Japan, and eastern Russia. Both haplotype and nucleotide diversities were extremely low in Europe and North America compared to northeast Asia. Our study indicates that the East Sea/Sea of Japan is a likely donor region of the invasive populations of G. vermiculophylla in the east and west Atlantic and the east Pacific.     

Reproductive ecology of the freshwater red alga Batrachospermum delicatulum (Batrachospermales, Rhodophyta) in three tropical streams

Batrachospermum delicatulum specimens from three stream segments were analyzed from a tropical region in south‐ eastern Brazil (20°18′– 20°49′S, 49°13′– 49°46′W). Physical and chemical parameters and the spatial placement of thalli were investigated along with the reproductive characteristics of the gametophytic phase. Sequence data of the cox 2‐ 3 spacer region was also utilized to evaluate genetic variation in individuals within and among stream segments. Gametophyte occurred under relatively diverse environmental conditions, whereas thalli abundance was weakly or not correlated to environmental variables within the stream segments. All specimens examined were dioecious. The ratio of male/female plants was relatively low (0.5 to 1.3) and male plants tended to occur as clumps (two or three plants together). High reproductive success was observed, as indicated by the occurrence of 100% fertilized (carposporophytic) female plants. This is similar to previous reports for this and other dioecious species, which is remarkable considering the relatively low proportion of male/female plants. Results support the two hypotheses to explain the high reproductive success in dioecious species. The occurrence of male plants in clumps was evidence for a strict spatial relationship (i.e. male plants located in upstream position of female plants in order to release spermatia, which would be carried by eddies through female plants). In contrast, the occurrence of male and female plants adjacent to each other allowed outcrossing among neighboring plants with intermingled male and female branches, which seemed more applicable to some situations (low turbulence habitats). The cox 2‐ 3 spacer region from the 18 individuals sequenced was 376 bp and the DNA sequence was identical with no base pair substitutions. Likewise, a previous study of another Batrachospermum species showed that the same haplotypes were present in all stream segments from the same drainage basin, even though the stream segments were a considerable distance apart. Short distance dispersal either by small birds or waterway connectivity might explain these findings.     

Expressed sequence tags (ESTs) from the marine red alga Gracilaria gracilis

Expressed sequence tags (ESTs) are partial sequences of cDNAs, and can be used to characterize gene expression in organisms or tissues. We have constructed a 200-sequence EST database from vegetative thalli of Gracilaria gracilis, the first ESTs reported from any alga. This database contains recognizable ESTs corresponding to genes of carbohydrate metabolism (seven), amino acid metabolism (three), photosynthesis (five), nucleic acid synthesis, repair and processing (three), protein synthesis (14), protein degradation (six), cellular maintenance and stress response (three), other identifiable protein-coding genes (13) and 146 sequences for which significant matches were not found in existing sequence databases. We have already used this EST database to recover genes of carbohydrate biosynthesis from G. gracilis. This revised version was published online in August 2006 with corrections to the Cover Date.