Extension of the rice DH population genetic map with microsatellite markers

Genetic mapping of microsatellite markers was carried out in a rice DH population derived from across between Zaiyeqing 8 (indica) and Jingxi 17 (japonica). A total of 89 microsatellite markers, including 84 (GA)_n, 2(TCT)_n, 2(ATT)_n, and, l(ATC)_n motifs, were integrated relatively evenly into the established genetic map of the DH population. This will facilitate the utilization of microsatillite markers in rice gene mapping and marker aided breeding.     

Inter- and intrapopulation studies of ancient humans

For a genetic analysis of ancient human populations to be useful, it must be demonstrated that the DNA samples under investigation represent a single human population. Toward that end, we have analyzed human DNA from the Windover site (7000–8000 BP). MHC-I analysis, using allele-specific oligonucleotide hybridization to PCR amplified Windover DNA, microsatellite analysis by PCR of the APO-A2 repeat and mtD-loop 3 region sequencing on multiple individuals spanning nearly the full range of estimated burial dates all confirm the hypothesis that there is a persistence of both nuclear and mitochondrial haplotypes at Windover throughout its entire period of use. Thus, Windover can be considered a single population. Neighbor-joining tree analysis of mtDNA sequences suggests that some mitochondrial types are clearly related to extant Amerind types, whereas others, more distantly related, may reflect genetically distinct origins. A more complete sequence analysis will be required to firmly resolve this issue. Calibrating genetic relationships deduced by tree analysis, radiocarbon dates and burial position, yields a human mtD-loop DNA rate of evolution of 3700 to 14,000 years per percent change. Both values are within the range of recent, independently calculated values using estimates of evolutionary divergence or theoretical population genetics. Thus we are beginning to relaize the promise of ancient DNA analysis to experimentally answer heretofore unapproachable questions regarding human prehistory and genetic change.     

Population genetic structure and mating system evolution in freshwater pulmonates

Freshwater gastropods (Basommatophora and Prosobranchia) harbor a variety of mating systems. In particular, apomictic parthenogenesis in prosobranchs and self-fertilization in the hermaphrodite pulmonates may be viable alternatives to outcrossing sexuality in a number of species. The coexistence of different mating systems in extant populations provides opportunities to examine the forces directing their evolution. We review the models analyzing and predicting genetic variability in subdivided populations, with an emphasis on the effects of inbreeding. Population genetic data on freshwater pulmonates are examined in the context of selfing rates and the loss of variability under selfing. Furthermore, the genetic and demographic factors thought to influence mating system evolution are considered, and we highlight the different approaches available to estimate mating system parameters, in particular the selfing rate. Recent population biological studies on polyploid species (Bulinus truncatus, Ancylus fluviatilis) indicate that selfing is the predominant mating system. These studies have contributed to a deeper understanding of conceptual issues in the evolution of selfing rates. Throughout, we emphasize the need for further carefully designed studies.     

对比性标记语的关联——认知分析

因其独特的对比性语义特征及其在话语生成和理解过程中必不可少的语用功能,对比性标记语在话语标记语的研究中逐渐占有特殊地位。以关联理论为框架,从关联—认知角度分析对比性标记语这一语言机制存在的依据,可知对比性标记语的程序性意义在话语生成和理解过程中发挥了特殊作用。     

话语标记语的语用功能及其对英语口语教学的启示

话语标记语是口语交际中特有的语用机制。在话语生成过程中，话语标记语具有为说话者合理组织并表达自己的思想从而促使交际顺利进行的功能。依据Sperber＆Wilson（1995）所提出的关联理论，从认知语用学角度分析其在话语生成和理解过程中的语用功能，并结合实际阐明：在话语生成过程中，话语标记语有助于说话者对听活者的话浯处理能力、语境信息等加以控制；有助于说话者在话语生成时更加灵活地组织语篇以达交际意图。教师在英浯u语孜学中，应高度重视话语标记语的重要性，并将其语用功能列入教学大纲有计划地讲授，以期有效交际的真正实现。     

中国人群eNOS基因内含子13微卫星多态性的初步研究

目的：为研究ｅＮＯＳ基因内含子１３上的微卫星序列与妊高症的相关性。方法：采用ＰＣＲ－ＰＡＧＥ与银染相结合的方法，研究其多态性。结果：得到含有该微卫星序列的ＤＮＡ片段。结论：证实在中国人群中ｅＮＯＳ基因内含子１３上的确存在一个ＣＡ重复的多态性微卫星序列，从而为研究该位点与妊高病的相关性提供了技术支持和理论依据。     

语篇标记语在英文写作中的使用

语篇的衔接和连贯需要借助许多手段,如指称、替代、省略和标记语。讨论了标记语与中国学生英语作文之间存在的相关关系,分析了标记语的错误使用和不当使用,并指出在外语教学中,尤其是写作教学中应对标记语的使用有一定重视。     

Identification and characterization of microsatellite markers for yellow grouper Epinephelus awoara and bluelined hind Cephalopholis formosa

0Introduction Groupershaveconsistentlyprovedhighlyvulnerable toanythingotherthanhighlevelsoffishingpressure.This islargelyduetotheirbiologicalcharacteristics.Yellow grouperEpinephelusawoaracanbeseeninHongKong livefishmarket[1].Manygrouperspeciesoncerecorded as“common”inHongKongarenowrarelyseen[2].Blue linedhindCephalopholisformosaisoftenmisidentifiedin thepetfishliteratureandsoldasC.boenakfromIndo westPacific.Cephalopholisispartofasub family(Epinephelinae)andfurthersub division(Tribe E…     

利用SSR 标记正确判断小麦杂交种中的杂株

 正确判断杂交种中混有的杂株, 是准确鉴定小麦杂交种种子纯度的前提。在分析180 份杂交组合的基础上, 以“京麦1100”为例, 提出了利用SSR 标记正确判断小麦杂交种中杂株的方法:1)筛选双亲间有多态性的引物不少于5 对;2)利用该引物检测亲本及杂交种的基因型, 并按照杂交种基因型记录原则记录每个个体的基因型;3)正确判断真实杂交种基因型:不论亲本是否存在非纯合位点现象, 只要某个体同时具备父母本的基因型, 均视为真实杂交种的基因型;4)判断杂株:当某个体在多个SSR 位点上与真实杂交种基因型不同时, 判断为杂株。