δO of carbonate, quartz and phosphate from belemnite guards: implications for the isotopic record of old fossils and the isotopic composition of ancient seawater     

Antonio Longinelli  Paola IacuminMichele Ramigni 《Earth and Planetary Science Letters》2002,203(1):445-459

Belemnite guards of Cretaceous and Jurassic age were found to contain varying amounts of quartz deposited both on the external surface and inside the rostrum. The oxygen isotopic composition of coexisting carbonate, quartz and phosphate from the same rostrum was measured according to well-established techniques. None of these compounds showed isotopic values in equilibrium with one another. Assuming δ¹⁸O values of the diagenetic water within the range of meteoric waters, the δ¹⁸O(SiO₂) yield temperatures in agreement with the apparent secondary origin of this phase. The δ¹⁸O(CO₃²⁻) range, with a certain continuity, between −10.8 and +0.97 PDB-1 with most of the intermediate values being within the range of the carbonate isotopic values of Mesozoic fossils. The most positive isotopic results obtained from phosphate are close to +23/+24‰ (V-SMOW). They can hardly be related to a secondary origin of the phosphate, or to the presence of diagenetic effects, since these results are among the most positive ever measured on phosphate. As far as we know there is no widespread diagenetic process determining an ¹⁸O enrichment of phosphate. The very low concentration of phosphate did not allow the determination of its mineralogical composition. All the available δ¹⁸O(PO₄³⁻) values from belemnite and non-belemnite fossils of marine origin of Tertiary and Mesozoic age are reported along with the newly measured belemnites. The following conclusions may be drawn from the data reported: (1) the pristine oxygen isotope composition of fossil marine organisms (either carbonate or phosphate) may easily undergo fairly large changes because of oxygen isotope exchange processes with diagenetic water; this process is apparent even in the case of geologically recent fossils; (2) the δ¹⁸O(PO₄³⁻) of belemnite rostra seems to be, at least in the case of the most positive results, in isotopic equilibrium with environmental water because of the similarity between the results from Cretaceous belemnites and the results from Cretaceous and Lower Tertiary pelecypods and fish teeth; 3) if so, the only feasible interpretation that can be suggested for the ¹⁸O enriched data is the possibility of a relatively large variation of the oxygen isotopic composition of ocean paleowater from Jurassic to recent time.  相似文献   

中国沿海常见蜑螺科贝类的DNA条形码   总被引：1，自引：0，他引：1  

张晓洁  孔令锋  李琪 《海洋与湖沼》2018,49(3):614-623

DNA条形码不仅为物种鉴定提供了有效方法,而且也有助于分类学和生物多样性研究。本研究旨在探讨将COI和16S rRNA基因序列应用于中国沿海蜑螺科贝类物种鉴定的可行性,获得了该科3属7种贝类61个个体的COI和16S rRNA基因序列。基于COI基因序列的种内遗传距离为0.00—1.29%,平均为0.67%;属内种间遗传距离为4.62%—19.25%,平均为13.02%;基于16S rRNA基因序列的种内遗传距离为0.00%—0.48%,平均为0.23%;属内种间遗传距离为2.47%—8.48%,平均为6.37%。两种基因序列在所研究的蜑螺中,种内遗传差异均小于种间遗传差异,存在明显的条形码间隙,所有物种在系统发生树上都表现为独立的单系群。结果表明,线粒体COI和16S rRNA基因序列可以作为DNA条形码标准基因对蜑螺科贝类进行有效地物种鉴定。  相似文献   

基于线粒体COI和16S rRNA基因的中国沿海相手蟹系统发育研究   总被引：2，自引：0，他引：2  

徐岩  潘红平  阎冰  高霆炜  吴斌  杨明柳 《海洋学报》2019,41(8):63-71

相手蟹科的诸多种类因其形态极其相似成为方蟹总科分类中疑问较多的一个类群。通过对中国沿海相手蟹线粒体COI和16S rRNA基因序列进行分子系统发育分析，结果表明14种相手蟹COI和16S rRNA基因序列之间差异分别为5.7%～14.5%和1.5%～12.1%，均达到了种间差异水平。构建的系统发育树显示，14种相手蟹分别为独立有效物种，但分属于拟相手蟹属和近相手蟹属的4种拟相手蟹和3种近相手蟹，没有分别形成2个独立的支系，而是混合聚成一大支系。而属于螳臂相手蟹属的无齿螳臂相手蟹则首先与属于中相手蟹属的中华中相手蟹聚成一支，再与红螯螳臂相手蟹聚为一大支，表现出与形态分类的不一致。错综复杂的分子系统关系预示着相手蟹类为多系起源，也表明它们之间的种间关系乃至于属间关系尚有诸多问题有待进一步厘定。  相似文献   

Molecular and morphometric characterisation of the invasive signal crayfish populations in Croatia     

《Limnologica》2017

The signal crayfish Pacifastacus leniusculus (Dana, 1852) is a native species to North America. It was introduced to Europe and Japan where it rapidly spread as an invasive species. In Croatia, it is recorded in the rivers Mura and Drava, where it spread downstream from Slovenia, and in the Korana River, where it has been recently illegally introduced. In the invaded areas, signal crayfish outcompetes native crayfish species. Since the knowledge on the genetic diversity of this invasive species is limited, microsatellite markers and sequences of mitochondrial gene for 16S rRNA were analysed to explore the genetic relations between the two Croatian populations (Mura and Korana rivers) as well as their relation to other already studied European populations. Moreover, 16S rRNA sequence fragments of Croatian samples were compared with those from the native range in the west North America. Morphometric characteristics were also studied to determine if there are significant differences between studied populations and if these are concordant with the genetic analyses results. Also, morphometric data were used to assign Croatian signal crayfish into subspecies classification according to Miller’s discriminant function formula, and to compare claw surface area among Croatian, Japanese and North American populations. Based on the results of morphometric characteristics Croatian samples showed Pacifastacus leniusculus leniusculus-like morphology. Phylogenetic reconstruction based on 16S rRNA, positioned Croatian samples into P. leniusculus sensu Larson et al. (2012). Results on microsatellite markers showed that the genetic diversity of P. leniusculus in the Mura River population is slightly higher compared to the Korana River population, but these two populations do not form separated genetic clusters. This study contributes to the knowledge on genetic variability and morphometric characteristics of signal crayfish in Europe and further understanding of its success as an invasive species.  相似文献   

宁波沿海陆源排污口放线菌(Actinomycetales sp.)的分布特点     

司开学  夏长革  王朝阳  张迪骏  何珊  周君  张红燕  韩姣姣  崔晨茜  董丽莎  苏秀榕 《海洋与湖沼》2016,47(2):400-406

利用454高通量测序技术对宁波沿海10个陆源排污口20个站位的放线菌的时空分布及5个工业排污口的放线菌的种类作了整体分析。成功鉴定出了83个属,84个种。研究结果显示:放线菌在陆源排污口的分布呈现季节性分布,从3月份到10月份,放线菌数量呈现先升高后下降的变化,5月份和8月份数量居高,在3月份和10月份偏低;在综合排污口(S4,S6,S8和S9)检测频次较高,在工业排污口(S1,S3,S5,S7和S10)检测频次居中,在市政排污口(S2)检出频次最低。不同类型的排污口,氨氮浓度的排出量不同,放线菌的种类和数量也不同。在5个工业排污口中,S7和S10检出的共同菌最多;在S7独自检出短双歧杆菌(Bifidobacterium breve)、长双歧杆菌(B.longum)和两岐双岐杆菌(B.bifidum),表明存在粪源污染物;在S5检出皱孢链霉菌(Streptomyces scabrisporus)和硫藤黄链霉菌(S.thioluteus),显示有石油降解物和重金属的污染。总体上看,放线菌数量在距排污口外50m处略高于排污口处。排放指标越相似,菌的种类越接近。  相似文献   

基于第二代测序技术的条斑紫菜(Pyropia yezoensis)贝壳丝状体附生菌群研究   总被引：1，自引：0，他引：1  

盖珊珊  张伟东 《海洋与湖沼》2016,47(5):990-996

条斑紫菜(Pyropia yezoensis)贝壳丝状体黄斑病给育苗产业造成危害,但目前对健康状态下的菌群结构及其发病后变化仍缺乏认识。本研究基于第二代测序技术和16S r RNA序列分析,对健康和患病丝状体的细菌组成与变化进行比较。测序共产生1.6Gb配对末端序列,获得了第一个高通量的条斑紫菜贝壳丝状体细菌群落数据集。通过数据分析共识别出7,833种可操作分类单元(operational taxonomic units,OTUs),比对确定为18个细菌门。相对于健康样本,黄斑病丝状体样本的微生物多样性显著增加。主坐标分析和非加权组平均法(unweighted pair group method using arithmetic average,UPGMA)聚类均将健康和黄斑病丝状体分成不同的组,且健康组样本间的距离明显小于黄斑病组。上述结果说明,健康贝壳丝状体保持着相似的微生物群落结构,而患病后的丝状体则发生了不同的变化;健康样本和黄斑病样本组间差异显著的细菌属有39个,其中29个在健康样本中的相对丰度明显高于病患组样本。本研究从菌群生态角度分析了健康贝壳丝状体微生物菌群结构、发病后菌群的变化及其对丝状体生长的潜在作用,为丝状体病害的检测和预防提供有价值的信息。  相似文献   

两种体色三疣梭子蟹线粒体DNA 部分片段序列的比较分析     

迟大利  高焕  沈颂东  阎斌伦 《海洋科学》2010,34(11):27-34

三疣梭子蟹(Portunus trituberculatus)作为重要的海洋经济动物,其常见体色(头胸甲)为茶绿色。近年来在我国沿海海域海捕三疣梭子蟹中开始出现体色为紫色的一类梭子蟹,除体色不同外,二者表型特征并无显著差异。对两种体色三疣梭子蟹不同个体的线粒体COI和16S rRNA基因进行了序列比对分析以判定二者之间的亲缘关系。结果发现COI和16S rRNA基因在两种体色三疣梭子蟹群体中的核苷酸序列一致性分别为99.87%和99.88%,表明紫色三疣梭子蟹并未发生亚种的分化,即紫色和茶绿色群体属于同一个种。并利用GenBank数据库检索了梭子蟹科其他15种海产蟹的16S rRNA序列,进行了序列同源性比对分析和分子系统学方面的探讨,为梭子蟹种属分类学研究提供分子依据。  相似文献   

两种体色三疣梭子蟹亲缘关系的PCR-SSCP分析     

迟大利  高焕  沈颂东  阎斌伦 《海洋通报(英文版)》2010,12(1):79-88

三疣梭子蟹作为重要的海洋经济动物，其常见体色为茶绿色。近年来在我国东部沿海海域海捕三疣梭子蟹中开始出现体色为紫色的一类梭子蟹，除体色不同外，二者表型特征并无显著差异。为确定两种体色三疣梭子蟹之间的关系，本文对两种体色三疣梭子蟹不同个体的线粒体COl和16srRNA基因进行了比较分析以判定体色的差异是否由于种属的差异引起的。通过对以上两个基因部分序列的SSCP和相关序列测定分析，发现在紫色和茶绿色群体中这两个线粒体保守序列基因的SSCP电泳条带图谱相似，序列分析表明COl和16srRNA基因在两种体色三疣梭子蟹群体中的核苷酸序列相似度分别为99．81％和99．91％。以上结果表明，紫色三疣梭子蟹并未发生亚种的分化，即紫色和茶绿色群体属于同一个种。此外，紫色梭子蟹群体的线粒体DNA序列在进化关系上较茶绿色群体更为保守。  相似文献   

RSM－16H动测仪在面波法岩土体检测中的应用   总被引：1，自引：0，他引：1  

黄嘉正  张学强  关小平 《岩土力学》1995,(2)

对在岩土体检测中推广应用的新技术──瑞雷面波法作了简述，介绍了ＲＳＭ－１６Ｈ型动测仪对稳态和瞬态面波资料的处理实例，并提出了对该仪器在面波测量中的软件改进建议。  相似文献   

Stochasticity of planetary orbits in double star systems. II     

Benest  D.  Gonczi  R.  Gonczi  R. 《Earth, Moon, and Planets》2003,93(3):175-190

Cosmogonical theories as well as recent observations allow us to expect the existence of numerous exo-planets, including in binaries. Then arises the dynamical problem of stability for planetary orbits in double star systems. Modern computations have shown that many such stable orbits do exist, among which we consider orbits around one component of the binary (called S-type orbits). Within the framework of the elliptic plane restricted three-body problem, the phase space of initial conditions for fictitious S-type planetary orbits is systematically explored, and limits for stability had been previously established for four nearby binaries which components are nearly of solar type. Among stable orbits, found up to distance of their sun of the order of half the binarys periastron distance, nearly-circular ones exist for the three binaries (among the four) having a not too high orbital eccentricity. In the first part of the present paper, we compare these previous results with orbits around a 16 Cyg B-like binarys component with varied eccentricities, and we confirm the existence of stable nearly-circular S-type planetary orbits but for very high binarys eccentricity. It is well-known that chaos may destroy this stability after a very long time (several millions years or more). In a first paper, we had shown that a stable planetary orbit, although chaotic, could keep its stability for more than a billion years (confined chaos). Then, in the second part of the present paper, we investigate the chaotic behaviour of two sets of planetary orbits among the stable ones found around 16 Cyg B-like components in the first part, one set of strongly stable orbits and the other near the limit of stability. Our results show that the stability of the first set is not destroyed when the binarys eccentricity increases even to very high values (0.95), but that the stability of the second set is destroyed as soon as the eccentricity reaches the value 0.8.  相似文献