Molecular phylogenetic analysis of attached Ulvaceae species and free-floating Enteromorpha from Qingdao coasts in 2007

Based on the sequence data of the nuclear ribosomal DNA internal transcribed spacer(ITS) 1,5.8 S,and ITS 2,the molecular phylogeny was analyzed on Ulvaceae species collected from Qingdao coasts in summer of 2007,including 15 attached Ulva and Enteromorpha samples from 10 locations and 10 free-floating Enteromorpha samples from seven locations.The result supported the monophyly of all free-floating Enteromorpha samples,implying the unialgal composition of the free-floating Enteromorpha,and the attached Ulvaceae species from Qingdao coasts were grouped into other five clades,suggesting that they were not the biogeographic origin of the free-floating Enteromorpha in that season.     

Molecular phylogenetic analysis of attached Ulvaceae species and free-floating <Emphasis Type="Italic">Enteromorpha</Emphasis> from Qingdao coasts in 2007

Based on the sequence data of the nuclear ribosomal DNA internal transcribed spacer (ITS) 1, 5.8 S, and ITS 2, the molecular phylogeny was analyzed on Ulvaceae species collected from Qingdao coasts in summer of 2007, including 15 attached Ulva and Enteromorpha samples from 10 locations and 10 free-floating Enteromorpha samples from seven locations. The result supported the monophyly of all free-floating Enteromorpha samples, implying the unialgal composition of the free-floating Enteromorpha, and the attached Ulvaceae species from Qingdao coasts were grouped into other five clades, suggesting that they were not the biogeographic origin of the free-floating Enteromorpha in that season. Supported by NSFC (40506030); the Innovative Key Project of the Chinese Academy of Sciences (KZCX2-YW-209); Science & Technology Project of Qingdao City (06-2-2-12-JCH)     

Genetic transformation of marine cyanobacterium Synechococcus sp. CC9311 (Cyanophyceae) by electroporation

Synechococcus sp.CC9311 is a marine cyanobacterium characterized by type IV chromatic acclimation(CA).A genetic transformation system was developed as a first step to elucidate the molecular mechanism of CA.The results show that Synechococcus sp.CC9311 cells were sensitive to four commonly used antibiotics:ampicillin,kanamycin,spectinomycin,and chloramphenicol.An integrative plasmid to disrupt the putative phycoerythrin lyase gene mpeV,using a kanamycin resistance gene as selectable marker,was constructed by recombinant polymerase chain reaction.The plasmid was then transformed into Synechococcus sp.CC9311 via electroporation.High transformation efficiency was achieved at a field strength of 2 kV/cm.DNA analysis showed that mpeV was fully disrupted following challenge of the transformants with a high concentration of kanamycin.In addition,the transformants that displayed poor growth on agar SN medium could be successfully plated on agarose SN medium.     

Ulva and Enteromorpha (Ulvaceae, Chlorophyta) from two sides of the Yellow Sea: analysis of nuclear rDNA ITS and plastid rbcL sequence data

Ulvacean green seaweeds are common worldwide; they formed massive green tides in the Yellow Sea in recent years, which caused marine ecological problems as well as a social issue. We investigated two major genera of the Ulvaceae, Ulva and Enteromorpha, and collected the plastid rbcL and nuclear ITS sequences of specimens of the genera in two sides of the Yellow Sea and analyzed them. Phylogenetic trees of rbcL data show the occurrence of five species of Enteromorpha (E. compressa, E. flexuosa, E. intestinalis, E. linza and E. prolifera) and three species of Ulva (U. pertusa, U. rigida and U. ohnoi). However, we found U. ohnoi, which is known as a subtropical to tropical species, at two sites on Jeju Island, Korea. Four ribotypes in partial sequences of 5.8S rDNA and ITS2 from E. compressa were also found. Ribotype network analysis revealed that the common ribotype, occurring in China, Korea and Europe, is connected with ribotypes from Europe and China/Japan. Although samples of the same species were collected from both sides of the Yellow Sea, intraspecific genetic polymorphism of each species was low among samples collected worldwide.     

马氏珠母贝水通道蛋白基因AQP4 cDNA克隆和表达分析

水通道蛋白4(aquaporin4, AQP4)是一类被动运输水的通道蛋白。本研究根据转录组测序获得的马氏珠母贝AQP4片段, 采用RACE技术获得了AQP4的全长cDNA, 命名为PfAQP4, 其5′非翻译区(untranslated region, UTR)为114bp, 3′UTR为839bp, 开放阅读框(open reading frame, ORF)为858bp, 编码285个氨基酸。PfAQP4含有6个α螺旋跨膜区、5个环、1个主要内嵌蛋白(major intrinsic protein, MIP)结构域、2个NPA(Asn-Pro-Ala)基序, 属于AQP1-like型。利用qPCR技术分析PfAQP4在不同组织、不同发育时期以及盐度胁迫条件下的mRNA表达模式。结果显示: (1) PfAQP4在所有被检测组织中均表达, 其中在闭壳肌、足和鳃中表达量较高; (2) PfAQP4在不同的发育时期均有表达, 其表达量整体呈现先升高后降低的趋势, 其中在2—4细胞期表达量最高, 在眼点幼虫期表达量最低; (3) 在高盐度组(36‰)盐度胁迫24、72、120h后, PfAQP4表达量显著上升, 在168h降至对照组水平; 在低盐(16‰)组, PfAQP4表达量在24h显著上调, 在72h恢复至对照组水平, 说明盐度影响鳃组织中PfAQP4的表达量, 也表明PfAQP4在马氏珠母贝渗透压调节中起着非常重要的作用。     

亚洲内陆干旱区NDVI与树木生长的气候响应及其影响因素

基于亚洲内陆干旱区的树木年轮宽度指数（RWI）、归一化差异植被指数（NDVI）和气候数据,采用空间统计方法和相关分析法分析了NDVI和RWI变化的一致性,探讨了NDVI和RWI对气候的响应,揭示了影响NDVI和RWI气候响应的相关因素。结果表明：1982—2000年亚洲内陆干旱区的树木生长和NDVI均呈增加趋势,生长季NDVI与RWI大多具有同步性变化特征,大多数地区5、6月NDVI受同期气温的影响,而4、5月NDVI主要受同期降水的影响;RWI主要受6—7月气温和4、6月和7月降水或帕默尔干旱指数（PDSI）的影响;大部分地区的NDVI和RWI对气温的响应具有一致性,但它们对降水或PDSI的响应存在很大差异;海拔和水热条件对不同地区的NDVI和RWI的气候响应有较大的影响。本研究对于认识亚洲内陆干旱区植被与树木生长的气候响应及其影响因素具有一定的科学意义。     

美国比格内尔山黄土的地球化学特征及其古气候意义

黄土是美国内布拉斯加州地表分布范围最广的沉积物之一,其中末次冰期形成的皮奥瑞亚黄土（Peoria loess,PL） 质量累积速率（Mass Accumulation Rate, MAR） 在比格内尔山（Bignell Hill,BH） 达到世界最高。探究此地区黄土快速沉积 的原因一直是北美中部大平原黄土研究的热点。本文通过对内布拉斯加州中部BH 样品的Nd、Sr 同位素、主微量和稀土元 素的分析,发现内布拉斯加黄土的化学成分相对均一,与上部大陆地壳（UCC） 和中国洛川黄土相比,Fe、Mg 值较低, K、Na 含量相对较高。BH 黄土的化学风化指数（CIA） 值平均为65.7,小于洛川黄土,显示出较弱的化学风化强度。Sr-Nd 同位素结果显示,除了普遍认为的怀特组沉积为黄土的主要源区外,还存在另一个87Sr/86Sr 比值更高, εNd更负的源区,推测 这个源区为北美劳伦冰盖冰川沉积,其对黄土的贡献达30%~45%。BH 黄土剖面的CIA、Na/K 和碳酸盐含量变化表明,在PL 形成时期（约25~18 ka）,化学风化较弱,气候干冷,有助于风尘产生与堆积。     

中国北方沙漠/沙地锆石形态特征及其对物源的指示

单颗粒锆石的形态、颜色等特征记录了其母岩结晶过程的温度、压力、结晶介质的化学性质等信息,鉴定不同沙漠/沙地碎屑锆石的晶体形态特征可以指示沉积物的原岩类型,进而可以帮助追溯物源.本文分析了中国北方塔克拉玛干沙漠、巴丹吉林沙漠、腾格里沙漠、毛乌素沙地、浑善达克沙地、科尔沁沙地等6个沙漠/沙地36个地表样品的碎屑锆石形态特征.结果显示,同一沙漠/沙地样品锆石形态特征较为一致,而不同沙漠/沙地样品锆石形态有差异.塔克拉玛干沙漠锆石多为无色或淡紫色,包裹体较少,锆石颗粒锥面较发育,短柱状锆石含量较多,指示该沙漠物质主要来自其北缘天山山脉早中生代碱性花岗岩.巴丹吉林沙漠和腾格里沙漠锆石形态特征较类似,相比较而言巴丹吉林沙漠锆石多为淡粉色,形态上锥面较发育,较少见到包裹体;而腾格里沙漠锆石颗粒细长柱较多和含包裹体颗粒较多,这两个沙漠物质可能来自其南部中央造山带的变质岩和其北缘中亚造山带早中生代碱性花岗岩.毛乌素沙地多为深色、锥面发育和短柱状颗粒锆石较常见,含包裹体颗粒较多,该沙地物质主要来自其西北孔兹岩带以及北部阴山山脉碱性花岗岩.浑善达克沙地锆石形态似毛乌素沙地,指示其物源与毛乌素沙地类似.科尔沁沙地锆石磨蚀严重,扁柱状锆石颗粒较常见,指示该沙地物质大部分来自其南缘燕山山脉的显生宙浅海沉积岩.本研究表明碎屑锆石形态特征可以指示沙漠或沙地沉积物的源区.     

Drainage evolution in intermontane basins at the Qinling-Daba Mountains

Science China Earth Sciences - River capture is of great significance to landform evolution and hominine migration. In the Qinling-Daba Mountains, there is a viewpoint that Jialing River captured...