长牡蛎(Crassostrea gigas)多代近交与自交家系遗传差异及生长性状比较

在良种选育过程中,为了尽快得到稳定可遗传的优良性状,常采用近交方式进行纯系选育,而近交会导致群体的遗传多样性下降。为了解长牡蛎(Crassostrea gigas)多代近交和自交家系的遗传多样性、遗传结构和生长情况,本实验选用长牡蛎近交4代(F4代)、近交5代(F5代)家系和雌性同体自交1代(自交1代)家系,采用8对多态性高的微卫星序列进行分析,同时对其成体的三个时间点生长数据进行了显著性差异分析。实验结果表明,8对微卫星位点在野生对照组中表现出较高的多态性,F4代、F5代和自交1代3个家系的遗传多样性明显下降,平均等位基因数(Na)由17.00下降到2.00,平均观测杂合度(Ho)由0.538下降到0.449,平均多态信息含量(PIC)由0.826下降到0.297;哈迪-温伯格平衡(HWE)检验结果显示,8个位点在三个家系和野生对照组中均不同程度偏离HWE平衡(P0.0062)。F4代、F5代、自交1代和野生对照的生长性状指标分析表明,和野生对照相比,三个家系生长指标明显提高,对于自交一代而言,与自交实验组亲本选择的偶然性有关。同时,三个家系三个时间点的壳长、壳宽生长性状没有显著性差异(除330日龄壳宽和630日龄壳长),F5代生长性状指标壳高和湿重均大于F4代和自交1代,且差异显著;但F4代和自交1代之间没有显著性差异。通过本研究发现,F5代可以继续用来进行生长性状新品系的选育,自交1代多样性降低程度相当于F5代,但多样性的降低对成体的生长性状影响不明显,仍可以用做相关实验材料。     

许氏平鲉(Sebastes schlegelii)速生选育群体的生长性能与遗传特征分析

本研究目的为开展许氏平鲉(Sebastes schlegelii)遗传改良和优质新品系选育,选取荣成(R)和长岛(C)的野生许氏平鲉为基础群体,采用群体选育(群体内和群体间)和家系选育相结合的方法,获得R-F1、RC-F1两个群体选育群体和R-F2、RC-F2、R-F3、RC-F3四个家系选育群体。对4个选育家系的生长性能进行比较分析,并利用20对高多态性的微卫星标记对8个群体进行遗传多样性检测。结果表明:(1)群体内和群体间家系选育子3代比家系选育子2代生长速度分别提高21.59%和30.99%。4个选育家系后代的绝对增重率随着天数的增加而上升,群体内家系选育(R-F3)的生长速度、绝对增重率显著大于群体间的杂交选育系(RC-F3),杂交系未表现出生长的杂种优势。(2)20对微卫星位点在所有群体中均表现出较高多态性,8个群体的平均有效等位基因数(Νe)为2.9849—7.9598,平均观测杂合度(oH)和期望杂合度(He)分别为0.7230—0.8405和0.6315—0.8716,平均多态信息含量(PIC)为0.6472—0.8478。经两代家系选育的R-F3和RC-F3平均等位基因数显著降低,但观测杂合度(Ho)和期望杂合度(He)均值仍达到0.7230、0.7549和0.6527、0.6315,还有维持了较高的遗传多样性水平,遗传潜力较大。Hardy-Weinberg平衡检测结果和遗传偏离指数(d)表明各群体在大约10个位点上表现出一定程度的杂合子缺失现象。群体间平均遗传分化系数(Fst)为0.1279,各群体间存在中等遗传分化程度。R与R-F1分别与RC-F3遗传距离最远(0.9959、0.9848),预测利用两组群体中生长优良个体分别进行杂交育种有可能获得杂种优势。     

Timing,magnitude and geochemistry of major Southeast Asian volcanic eruptions: identifying tephrochronologic markers

We review the current knowledge about Southeast Asian volcanoes and their eruption histories, and focus on identifying tephrochronologic markers representing major explosive eruptions in order to further future palaeoclimate and volcanological studies. Forty-one volcanic edifices in Southeast Asia have been classified as large calderas by Whelley et al. (2015) and thus have, or are likely to have, produced large explosive eruptions with a Volcanic Explosivity Index (VEI) of 6–8. Unfortunately, only 20 such eruptions have known ages, spanning from 1.2 Ma to 1991 ad , and fewer have geochemical data that can be used for tephrostratigraphic correlations. Volcanic products from different geodynamic regions and different sources can generally be distinguished on major element plots (e.g. K₂O versus CaO) of matrix glass composition. However, the distinction of multiple eruptions from the same source often requires additional data such as trace element compositions of matrix glass and/or mineral compositions. Biotite, but also magnetite compositions (MgO and TiO₂ content in particular) appear to be very discriminating. Up to nine tuffs in addition to the three to four Toba tuffs can be utilised as widespread tephrochronologic markers and span a range from 1.2 to 1.6 Ma to recent. As only a few Holocene major eruptions have been well characterised and dated, many large calderas are still unstudied, and many distal tephra layers are still lacking a source, more tephrochronologic markers can certainly be defined in the future.     

Isolation via enrichment and characterization of ten polymorphic microsatellite loci in the cuttlefish, Sepiella maindroni de Rochebruns

Ten novel polymorphic microsatellite loci were developed using an enrichment and colony hybridization protocol and characterized for the cuttlefish, Sepiella maindroni. Polymorphism was explored by using 30 individuals from the coastal waters of Zhanjiang, Guangdong province, China, in December 2007. The number of alleles ranged from 5 to 13. The ranges of observed and expected heterozygosity were from 0.578 9 to 1.000 0 and 0.682 8 to 0.925 7, respectively, and the average polymorphic information content (PIC) was 0.778 5. These microsatellite loci will certainly facilitate the detection of the genetic variation and population structure of S. maindroni.     

Microsatellite DNA polymorphisms and the relation with body weight in sea cucumber Apostichopus japonicus

The relationship between microsatellite polymorphism and body weight of captive bred Chinese sea cucumber Apostichopus japonicus was investigated in two local populations in Dalian.Among ten loci discovered, nine show changes except for A J07 loci. Seven loci were found highly polymorphic in both populations. For each locus in two populations, the average number of alleles is 6.428 6 and 6.285 7, the average observed heterozygosity at 0.225 7 and 0.245 9, the expected heterozygosity at 0.776 8 and 0.748 8, the polymorphism information content (PIC) at 0.709 2 and 0.674 6, respectively. Further analysis show significant correlation between A. japonicus body weight and occurrence markers AJ02 and AJ04. The findings of the relation may be helpful for molecular breeding,as well as the marker-assisted selection of sea cucumbers.     

不同地理品系卤虫的同工酶变异初步研究

利用聚丙烯酰胺凝胶电泳方法，对国内外不同生态地区的孤雌生殖和两性生殖卤虫进行了酯酶（ＥＳＴ）、四唑氧化酶（ＴＯ）和碱性磷酸酶（ＡＬＰ）同工酶变异分析。指出不同地理品系卤虫有其独特的ＥＳＴ和ＴＯ标志酶带；孤雌生殖卤虫具有与两性生殖卤虫显著不同的ＴＯ基本带型和ＡＬＰ标志带区。这些结果为卤虫地理品系的纯度鉴定，以及两种生殖方式卤虫的分类和鉴别提供了生化指标。     

皱纹盘鲍杂交F1代与亲本的RAPD标记及分离方式分析

应用RAPD标记技术对皱纹盘鲍杂交家系JC的双亲及3个F₁个体进行了分析,对JC家系在皱纹盘鲍遗传连锁图谱构建中的应用前景进行了初步评估,并分析了RAPD分子标记在JC家系F₁代中的分离方式及该家系的1对亲本及其子代个体的遗传结构.7条随机引物共扩增出41个分子标记,其中24个为多态性,占总数的58.5%;有14个分离标记可用于遗传连锁作图,有7个符合孟德尔独立分配定律,占总数的17.1%.2个标记与子代个体大小有一定的相关性,但其连锁关系仍有待于进一步研究.父母本之间的遗传距离为0.384 4,父本与子代间的距离为0.137 2,母本与子代间的距离为0.127 3;父本提供的分离标记在子代中的显性频率为0.47,母本为0.55.双亲之间的遗传距离较远,杂交产生的JC-F₁群体具有较高的杂合度(0.201 6),该结果初步表明皱纹盘鲍杂交家系JC的子1代即可作为作图群体应用于皱纹盘鲍的连锁图谱构建.     

4种养殖扇贝的群体遗传多样性及特异性AFLP标记研究

应用AFLP技术对我国4种主要养殖扇贝进行了遗传分析.虾夷扇贝、海湾扇贝、华贵栉孔扇贝、栉孔扇贝4种养殖扇贝群体中,种内遗传相似度依次分别为0.841 5,0.786 3,0.719 0和0.673 1,香侬氏指数分别为43.52,58.87,80.16和92.83,栉孔扇贝和华贵栉孔扇贝的遗传多样性水平明显高于海湾扇贝和虾夷扇贝;AFLP标记共享位点分布表明,在4种扇贝中栉孔扇贝与华贵栉孔扇贝之间的共享位点最多,同时4种扇贝的种间遗传相似度也以栉孔扇贝和华贵栉孔扇贝之间为最高(0.769 5),海湾扇贝和虾夷扇贝之间为最低(0.662 6),揭示所研究的几种扇贝中栉孔扇贝和华贵栉孔扇贝的遗传关系最近(遗传距离为0.262 1);找到了21个种内特异性AFLP标记和种间共享标记,可用于种质鉴定和分子辅助分类.     

微卫星DNA标记技术及其在海洋生物遗传学中的应用

DNA简单重复序列从1974年在海洋生物中被发现,到1989年“微卫星”术语开始使用这段时间是这种新型分子标记技术的发展阶段。伴随着PCR技术的发明、成熟与拓展,微卫星DNA以其多态性高、随机分布、共显性遗传、重复性好等特点在生物学的个体及系统发育方面得到很广泛的应用。本文从微卫星DNA的发展简史开始,较详细地介绍了它的原理、方法及策略,然后概括了在海洋动、植物的遗传学中,微卫星DNA在遗传多样性分析、遗传图谱构建、基因鉴定和标记以及系谱认证等领域的研究,展望了其在海洋生物分子育种、基因克隆、生物保护等方面的应用前景。     

EST-SSR标记的开发及其在南黄海浒苔研究中的应用

Ulva species can grow rapidly in nutrient-rich habitats causing green tides and marine fouling. A more complete understanding of the reasons behind these outbreaks is urgently required. Accordingly, this study attempts to use microsatellite markers based expressed sequence tag（EST） to analyze the genetic variation of several Ulva prolifera populations in the South Yellow Sea of China. Two hundred and thirty-eight SSRs were identified from 8 179 unique ESTs（6 203 newly sequenced and 1 976 downloaded from NCBI database） and 37 primer pairs were successfully designed according to the ESTs; 11 pairs were selected to detect the genetic diversity and relationship of 69 attached U. prolifera samples and 13 free-floating samples collected from coastal and off-coast areas of the South Yellow Sea. The results of cross-species transferability showed that six of the 11 EST-SSR primers could give good amplification in other five Ulva species and the average allele number was 4.67. Genetic variation analysis indicated that all 82 U. prolifera samples were clearly divided and most samples collected from the same site clustered together as a group in the dendrogram tree produced by unweighted pair-group mean analysis（UPGMA） method and the cluster results showed some consistency with the geographical origins. In addition, 13 free-floating samples（except HT-001-2） were grouped as a single clade separated from the attached samples.