West versus East Mediterranean Sea: origin and genetic differentiation of the sea cucumber Holothuria polii          下载免费PDF全文

Sara Valente  Ester A. Serrão  Mercedes González‐Wangüemert 《Marine Ecology》2015,36(3):485-495

We studied the genetic structure of the sea cucumber Holothuria (Roweothuria) polii (Delle Chiaje 1823) by analysing the mitochondrial DNA variation in two fragments of cytochrome oxidase I (COI) and 16S genes. Individuals were collected in seven locations along the Mediterranean Sea, which cover a wide range of the species distribution. We found high haplotype diversity for COI and moderate diversity for 16S, and low nucleotide diversity for both genes. Our results for the COI gene showed many recent and exclusive haplotypes with few mutational changes, suggesting recent or ongoing population expansion. The Western and Eastern Mediterranean populations exhibited slight but significant genetic differentiation (COI gene) with higher genetic diversity in the East. The most ancient haplotype was not present in the westernmost sampling location (SE Spain). The oldest expansion time was observed in Turkey, corresponding to mid‐Pleistocene. Turkey had also the highest genetic diversity (number of total and exclusive haplotypes, polymorphisms, haplotype and nucleotide diversity). This suggests that this region could be the origin of the subsequent colonizations through the Mediterranean Sea, a hypothesis that should be assessed with nuclear markers in future research.  相似文献   

Induction of DNA strand breaks in the mussel (Mytilus trossulus) and clam (Protothaca staminea) following chronic field exposure to polycyclic aromatic hydrocarbons from the Exxon Valdez spill   总被引：1，自引：0，他引：1  

Thomas RE  Lindeberg M  Harris PM  Rice SD 《Marine pollution bulletin》2007,54(6):726-732

In 2002, 13 years after the Exxon Valdez spill, mussels and clams were examined for lingering oil exposure and damage. Known oil patches were sampled at four locations, and compared to nearby reference areas (same bay), and were also compared to "hot reference" sites to verify the methods used (Cordova harbor and fresh diesel spill at Port Chalmers). Passive samplers deployed for a month at the sites, along with tissue samples, confirmed that the oiled sites were oiled (fingerprinting back to Exxon Valdez oil) and that reference sites were clean. The highest PAH loads were detected in sub-surface interstitial waters at oiled sites. Exposure at the surface was generally low level, and probably intermittent. DNA damage was assessed in blood cells using sensitive comet analyses. DNA strand breakage was detected in both mussels and clams, with the highest level of damage detected at "hot reference" sites of Cordova harbor and Port Chalmers. Bioavailability and DNA damage at the oiled sties was low, indicating there has been substantial progress in recovery from the spill 13 years before, yet low level bioavailability and damage were still detectable.  相似文献   

用于构建生物系统发育树的古DNA序列     

唐先华  赖旭龙 《地质科技情报》2001,20(3):35-40

主要综述了古 DNA研究进展以及结合古 DNA序列和基因库中的数据构建系统发育树。这些研究能解决许多有关演化生物学、考古学、人类演化及迁移、动植物的家养和驯化过程及早期农业的发展、考古点的动植物残骸的精确鉴定及地质演化等问题。另外 ,还列举了一些重要的实例  相似文献   

Magnetic, geochemical and DNA properties of highly magnetic soils in England   总被引：11，自引：0，他引：11  

J. A. Dearing  J. A. Hannam  A. S. Anderson †  E. M. H. Wellington 《Geophysical Journal International》2001,144(1):183-196

  相似文献   

Hydrogen absorption lines in the cosmic microwave background spectrum     

V. K. Dubrovich  N. N. Shakhvorostova 《Astronomy Letters》2004,30(8):509-513

We have calculated the intensities of the subordinate hydrogen lines formed during the recombination epoch at redshifts 800?z?1600. We show that an allowance for the angular momentum splitting of hydrogen atomic energy levels and the dipole transition selection rules can reveal absorption features in the cosmic microwave background recombination spectrum in the submillimeter wavelength range.  相似文献   

Induction of thymine dimers by solar radiation in natural freshwater phytoplankton assemblages in Patagonia, Argentina     

Manfred Klisch  Rajeshwar P. Sinha  E. Walter Helbling  Donat-P. Häder 《Aquatic Sciences - Research Across Boundaries》2005,67(1):72-78

  相似文献   

New aerosol particle formation via certain ion driven processes     

A. Luts  T.-E. Parts  M. Vana 《Atmospheric Research》2006,82(3-4):547

Ions can speed up the formation of aerosol particles. The former studies have mainly concerned on the role of the ion charge itself. We have studied the possible (additional) role of the actual small air ion spectrum shape, and the quantitative role of ion–ion recombination pathway. By means of our ion evolution model, formation of new species (H₂SO₄)_n(NH₃)_m(HNO₃)_k via ion–ion recombination was investigated. The model shows how the generation rate of the new species depends on the concentrations of H₂SO₄ and NH₃, and how it depends on the tropospheric background aerosol situation. The rate can be up to a few new neutral complexes per cubic centimeter and per second. New particle generation via ion–ion recombination provides an extra channel, especially for the clean atmosphere. Former results have shown that such situations are often present in Antarctica. Our aerosol spectrum measurements reveal a number of similar non-Antarctic results. Sometimes, such situations are followed by aerosol bursts, which may be (partly) due to an ion–ion recombination channel.  相似文献   

Divergence of Parartemia and Artemia haemoglobin genes     

M. Coleman  M.C. Geddes  C.N.A. Trotman 《International Journal of Salt Lake Research》1998,7(2):171-180

Parartemia is a genus of brine shrimp endemic to Australia which is related to the more widespread and economically importantArtemia sp. The expression of a multimeric haemoglobin molecule inArtemia is well documented but inParartemia only trace levels of a possible haemoglobin have been observed. In this paper we describe the DNA sequence of a domain of a haemoglobin molecule inParartemia. The derived amino acid sequence suggests that the possible date of divergence about 85 million years ago of the two genera predates the divergence of the C and T polymers ofArtemia haemoglobin. This date would correlate with the physical and temporal isolation of Australia in the late Mesozoic.  相似文献   

无机离子（Ni，Ge）和烷化剂对DNA　Tm值的影响     

万红 《华北地质矿产杂志》1996,(2)

在实验室条件下，选择几种有代表性的无机离子（包括宏观生命元素、微量生命元素、副生命元素），并保持一定的浓度和ＰＨ值（６．１８±０．２），研究了各无机离子和烷化剂对ＤＮＡＴｍ值的影响。结果表明，有益元素与有害元素对ＤＮＡＴｍ值高低的影响明显不同。前者使Ｔｍ升高，抑制ＤＮＡ热变性，后者使Ｔｍ值降低，促进ＤＮＡ热变性；这并非阴阳离子的离子强度造成的，而是由于加入的无机离子对ＤＮＡ分子中磷酸基因和碱基的作用不同所致。而且它们对ＤＮＡＴｍ值的影响幅度和方向与烷化剂的存在有很大关系。烷化剂可以大大降低Ｔｍ值，加入各种无机离子对烷化作用产生不同的影响。这表明，作为致癌的主要机理—烷化作用可能与各种离子的存在和在生物体内的平衡状态有关。所测结果还表明，烷化剂的作用比无机离子大得多。这些结果有助于区分有害与有益元素，对癌症的早期发现及阐明致癌、防癌机理有重要意义。  相似文献   

Construction of a Metagenomic DNA Library of Sponge Symbionts and Screening of Antibacterial Metabolites   总被引：1，自引：0，他引：1  

CHEN Juan ZHU Tianjiao LI Dehai CUI Chengbin FANG Yuchun LIU Hongbing LIU Peipei GU Qianqun ZHU Weiming 《中国海洋大学学报(英文版)》2006,5(2):119-122

To study the bioactive metabolites produced by sponge-derived uncultured symbionts, a metagenomic DNA library of the symbionts of sponge Gelliodes gracilis was constructed. The average size of DNA inserts in the library was 20 kb. This library was screened for antibiotic activity using paper disc assaying. Two clones displayed the antibacterial activity against Micrococcus tetragenus. The metabolites of these two clones were analyzed through HPLC. The result showed that their metabolites were quite different from those of the host E. coli DH5α and the host containing vector pHZ132. This study may present a new approach to exploring bioactive metabolites of sponge symbionts.  相似文献