深海沉积物中微量DNA的提取及应用

采用化学裂解和酶解相结合的方法，进行了深海沉积物中微量DNA的提取，并采用DNA吸附树脂进行纯化。结果表明，该方法能有效地去除沉积物中的腐殖酸等抑制剂，每克湿重沉积物样品可得到DNA约16μg，回收率可达95％，所得到的DNA分子片段均在23kb左右，纯化后的DNA可直接应用于各种分子生物学操作。利用细菌16SrDNA通用引物对所提取的深海沉积物DNA进行了PCR—RRJ及系统发育分析，各主要细菌类群均能检出，证实该方法可以应用于深海等极端环境中微生物的多样性调查、系统发育分析以及特殊功能基因的筛选，同时还可应用于环境样品中生物量的半定量估计。     

DNA分子标记技术在海带遗传育种研究中的应用

本文系统地介绍了部分常用的DNA分子标记技术,并结合我国海带养殖情况阐述了遗传标记技术在海带及大型海藻遗传育种中的应用。     

耳壳藻内酯分子合成及其抗肿瘤活性的研究

采用四甲基偶氮唑盐(MTT)法体外肿瘤细胞株抑制试验，研究耳壳藻内酯合成过程中结构的衍化物和抗肿瘤活性的关系。结果表明．耳壳藻内酯对小鼠肝细胞癌(H22)、小鼠路易斯肺癌(LLC)、人宫颈癌(Hela)和人乳腺癌(MCF-7)有较强的细胞毒性，对正常小鼠胚成纤维(NIH3T3)和人肝细胞(L—02)的毒性较低。酮基内酯对各肿瘤细胞毒性差异较大，对上述正常细胞株的杀伤力也较大。体外结合DNA的研究表明，耳壳藻内酯芳香环上的羟基较酮基内酯上的酮基易于插入DNA分子中．造成DNA分子的断裂和解聚。标记代谢物前体掺入试验表明，耳壳藻内酯能够显著抑制DNA大分子的合成，阻滞肿瘤细胞的生长。推测耳壳藻内酯芳香环上的羟基是影响其抗肿瘤活性的主要官能团。     

Loss Processes of Sinking Fecal Pellets of Zooplankton in the Mesopelagic Layers of the Antarctic Marginal Ice Zone

A time-series sediment trap deployment was carried out in the marginal ice zone (MIZ) of the Antarctic Ocean (64°42′ S, 139°58′E; sea depth of 2930 m), during the austral summer. Cylindrical fecal pellets were the predominant sinking particles at 537 m in the middle of January and most of them disappeared below that depth, the loss of which were 25.3 mg C m⁻² day⁻¹ in the depth range of 537–796 m. Small-sized sinking particles other than fecal pellets increased in that depth range. Analyses of fecal pellets for remnant DNA corresponding to 16S mitochondrial RNA and 28S ribosomal RNA suggested that the large cylindrical fecal pellets at 537 m were produced by Antarctic krill (Euphausia superba) and copepods. According to the presence of the DNA associated with sinking particles, E. superba fecal pellets rapidly disappeared below 537 m, while copepod fecal pellets still remained in the mesopelagic and bathypelagic layers. Small-sized amorphous sinking particles at 537 m also contained E. superba- and copepod-derived DNA. The abundance of trap-collected copepods (Oithona spp. and Oncaea spp.) which are known to be coprophagous increased at 796 m where many fecal pellets disappeared. We suggest that those rapidly sinking pellets were fragmented by copepods with intensified coprorhexy activity (fragmentation of fecal pellets) in the mesopelagic layers, reducing their sinking rates. These smaller and slower sinking particles can be important food sources for detritivorus or coprophagous animals in mesopelagic and bathypelagic layers in the MIZ. This revised version was published online in July 2006 with corrections to the Cover Date.     

海产贝类DNA提取及PCR扩増

本文报道海产贝类DNA提取方法及PCR扩增。采用随机引物N01-20共获得391个片段。其中皱纹盘鮑2个个体,产生65个片段,在501-2818bp间;毛蚶3个个体,产生76个片段，在398-2818bp间;四角蛤蜊3个个体,产生154个片段,在562-3311bp间;中国蛤蜊2个个体，产生96个片段,在478-3311bp间。通过比较分析,可见海产贝类有丰富的遗传多态现象,RAPD技术可用于海产贝类的分类及系统演化关系探讨等领域。     

Habitat and leaf cytogenetic characteristics of Deschampsia antarctica Desv. in the Maritime Antarctica

Antarctic hairgrass (Deschampsia antarctica Desv.) was studied in the Maritime Antarctica with respect to general ecological characteristics, soil conditions, viral contamination, cell nucleus area, and relative DNA content. Material was gathered in six localities that were highly diverse in terms of the nature of soil-like substrata, presence of viral antigen determinants, and the average nucleus area and relative DNA content in leaf epidermis and parenchyma cells. Our results show that Antarctic hairgrass lives upon soils that are variable with respect to trace elements, pH, and other soil characteristics. The hairgrass is susceptible to a number of viruses, and shows substantial variation in DNA content and nucleus size.     

Beringia as an Ice Age genetic museum

Thousands of Late Pleistocene remains are found in sites throughout Beringia. These specimens comprise an Ice Age genetic museum, and the DNA contained within them provide a means to observe evolutionary processes within populations over geologically significant time scales. Phylogenetic analyses can identify the taxonomic positions of extinct species and provide estimates of speciation dates. Geographic and temporal divisions apparent in the genetic data can be related to ecological change, human impacts, and possible landscape mosaics in Beringia. The application of ancient DNA techniques to traditional paleontological studies provides a new perspective to long-standing questions regarding the paleoenvironment and diversity of Late Pleistocene Beringia.     

Phylogeny, diet, and habitat of an extinct ground sloth from Cuchillo Curá, Neuquén Province, southwest Argentina

Advancements in ancient DNA analyses now permit comparative molecular and morphological studies of extinct animal dung commonly preserved in caves of semiarid regions. These new techniques are showcased using a unique dung deposit preserved in a late glacial vizcacha (Lagidium sp.) midden from a limestone cave in southwestern Argentina (38.5° S). Phylogenetic analyses of the mitochondrial DNA show that the dung originated from a small ground sloth species not yet represented by skeletal material in the region, and not closely related to any of the four previously sequenced extinct and extant sloth species. Analyses of pollen and plant cuticles, as well as analyses of the chloroplast DNA, show that the Cuchillo Curá ground sloth browsed on many of the same herb, grass, and shrub genera common at the site today, and that its habitat was treeless Patagonian scrub-steppe. We envision a day when molecular analyses are used routinely to supplement morphological identifications and possibly to provide a time-lapse view of molecular diversification.     

Detecting genotoxicity using the Comet assay following chronic exposure of Manila clam Tapes semidecussatus to polluted estuarine sediments

Sediments frequently cause damage to biota due to the accumulation of toxic compounds and the bioavailability of sediment-bound contaminants. Damage can be assessed using biomarkers, such as the degree of genotoxic impact following in vivo exposure to pollutants. Genotoxic damage, expressed as single-strand DNA breaks, was measured in cells isolated from haemolymph, gill and digestive gland from the clam Tapes semidecussatus, using the single cell gel electrophoresis (Comet assay). Clams were exposed for three weeks to sediment samples collected from a polluted site and a ‘clean’ reference site.The level of DNA damage was assessed using an image analysis package and expressed as Tail Moment. Throughout the study, significant differences in DNA damage were recorded for each tissue type between clams exposed to the two sediment samples. We conclude that the Comet assay is a useful tool for the detection of DNA damage in clams chronically exposed to polluted sediments.