Ion Probe Study of Silicate Inclusions from Colomera （IIE） Iron Meteorite： the Rare Earth Element Perspective

Coupled with a petrographical study, I carried out an ion probe study of rare earth element microdistributions in mineral phases of silicate inclusions from the Colomera IIE iron meteorite. Most mineral grains have homogeneous REEs, but show considerable inter-grain variations by a factor of 2 to 100. The whole rock REE abundances for Colomera,estimated by combining REE data with modal abundances, are relatively LREE-enriched with REEs of～10’CI, which suggest that Colomera silicates were highly differentiated and might represent a low degree partial melt (-10%) of a chondritic source. REE geochemistry of Colomera silicate inclusions points to an origin that involves differentiation,dynamic mixing, remelting, reduction, recrystallization, and subsequent rapid cooling near the surface of a planetary body.     

3种星虫线粒体16S rRNA、COI和Cyt b基因片段的序列比较

对裸体方格星虫(Sipunculus nudus)、可口革囊星虫(Phascolosoma esculenta)和澳洲管体星虫(Siphonosoma australe)的线粒体16S rRNA、COI和细胞色素b(Cytb)基因片段序列进行比较,并对其系统发生进行了初步探讨。采用PCR方法得到总长度分别为531～544bp(16S)、652～675bp(COI)和406～453bp(Cytb)的线粒体片段。片段碱基A+T比例较高(16S rRNA基因58.3%,COI基因56.9%,Cytb基因59.5%)。16S rRNA片段存在169个碱基变异位点(其中包括167个简约信息位点)和44个碱基插入/缺失,种内个体间变异较小;COI片段有512个碱基(333个简约信息位点)存在变异,79个碱基插入/缺失;Cytb片段存在347个碱基(318个简约信息位点)变异位点,16个碱基插入/缺失。数据分析结果支持3种星虫和环节动物的分类地位较近,与软体动物较远的分类观点。此外,裸体方格星虫与澳洲管体星虫之间亲缘关系较近(D=0.3159、0.3156、0.2361)。认为3种星虫线粒体16S rRNA、COI和Cytb基因在种间存在明显的多态性,证实了三种基因序列均普遍适用于星虫种及以上阶元的系统学分析。     

DN A条形码技术及其在海洋贝类种质资源保护中的应用

DNA条形码技术是一种新兴的分子鉴定方法,是指通过选择一段DNA基因序列片段作为条形码进行物种鉴定、系统发育研究和物种多样性保护等。海洋贝类种类丰富、数量众多,传统的形态分类方法有一定的局限性,对一些非常见及疑难物种不能快速、准确地鉴定。作为一种快速、高效的物种诊断技术,DNA条形码技术在海洋贝类种质资源保护与利用方面起到了至关重要的作用。本文就DNA条形码的产生、原理、分析步骤、优势、局限及在海洋贝类种质资源保护中的应用进展进行了综述,并对其未来的发展进行了分析展望。     

广东沿海杂色鲍养殖群体遗传多样性的微卫星分析

实验选取的7个杂色鲍(Haliotis diversicolor)养殖群体分别来自广东汕头、汕尾、惠东、湛江和徐闻,深圳野生驯养,利用7对微卫星引物对上述群体进行了遗传多样性和群体遗传结构的分析。结果显示:7个位点产生的等位基因数从7～13个不等,共检测到68个等位基因,平均每个位点的等位基因数为9.71个。有效等位基因数的范围为3.8～8.1,平均观测杂合度范围为0.422～0.906,平均期望杂合度范围为0.748～0.917。7个群体的多态信息含量变化范围为0.657～0.883,PIC值均在0.500以上,表现为高度多态性。与两个野生驯养的养殖群体相比,其他5个养殖群体均存在不同程度的遗传多样性降低。AMOVA分析显示,4.79%的遗传变异来自于群体之间,95.21%的变异来自于群体内的个体之间。研究表明,广东沿岸的杂色鲍具有较高的遗传多样性水平,7个群体之间呈现一定的遗传分化。     

利用核酸适配体的竞争置换作用检测溶藻弧菌(Vibrio alginolyticus)

溶藻弧菌(Vibrio alginolyticus)是水产养殖中致病性较强的一种条件致病菌,为更灵敏、高效地对其进行检测,研发出一种基于核酸适配体竞争置换作用的检测方法。首先设计并制备出磁珠-核酸适配体-荧光报告探针的检测复合物(MAP检测复合物),然后利用溶藻弧菌与其核酸适配体有较好的亲和特异性,在对样品进行检测时,样品中的溶藻弧菌就会竞争MAP检测复合物中的核酸适配体,从而置换出与该核酸适配体结合的荧光报告探针,再通过检测置换出的报告探针的荧光强度来表征溶藻弧菌的浓度,从而实现对溶藻弧菌的定量检测。结果表明,该方法对溶藻弧菌的检测限可达到1CFU/mL,与嗜水气单胞菌(Aeromonas hydrophila)、迟钝爱德华氏菌(Edwardsiella tarda)、哈维氏弧菌(Vibrio harveyi)、大肠杆菌(Escherichia coli)等水产养殖中的常见致病微生物没有交叉反应,并在1~20、20~100和100~1000 CFU/mL范围内都表现出较好的线性关系。另外还对MAP检测复合物的制备条件进行了优化,较为理想的制备条件为:100nmol/L核酸适配体与100nmol/L荧光报告探针按体积比1︰1混合结合30 min,制备出50 nmol/L的核酸适配体-荧光报告探针复合物,然后该复合物再与25μg/mL的磁珠按体积比1︰1混合结合60 min,制备出相应的MAP检测复合物。利用核酸适配体的竞争置换作用检测溶藻弧菌有较好的灵敏度和特异性,展现了较好的应用前景。     

16S rRNA is a better choice than COI for DNA barcoding hydrozoans in the coastal waters of China

Identification of hydrozoan species is challenging, even for taxonomic experts, due to the scarcity of distinct morphological characters and phenotypic plasticity. DNA barcoding provides an efficient method for species identification, however, the choice between mitochondrial cytochrome c oxidase subunit I（COI） and large subunit ribosomal RNA gene（16S） as a standard barcode for hydrozoans is subject to debate. Herein, we directly compared the barcode potential of COI and 16S in hydrozoans using 339 sequences from 47 pelagic hydrozoan species. Analysis of Kimura 2-parameter genetic distances（K2P） documented the mean intraspecific/interspecific variation for COI and 16S to be 0.004/0.204 and 0.003/0.223, respectively. An obvious ＂barcoding gap＂ was detected for all species in both markers and all individuals of a species clustered together in both the COI and 16S trees. These results suggested that the species within the studied taxa can be efficiently and accurately identified by COI and 16S. Furthermore, our results confirmed that 16S was a better phylogenetic marker for hydrozoans at the genus level, and in some cases at the family level. Considering the resolution and effectiveness for barcoding and phylogenetic analyses of Hydrozoa, we strongly recommend 16S as the standard barcode for hydrozoans.     

星洲银罗非鱼线粒体细胞色素b基因的序列分析

克隆并测定了星洲银罗非鱼(Oreochromis sp.)细胞色素b基因(cyt b)的全序列,得到全长1 141bp的序列用于分析,用MEGA4.0分析软件与GenBank中的线粒体DNA序列进行序列比较,显示星洲银罗非鱼与其他鱼类的cyt b基因的同源性较高,同源度介于83%~93%间;根据星洲银罗非鱼与莫桑比克罗非鱼、尼罗罗非鱼等12种鱼类的cyt b基因序列构建的系统进化树,初步确定尼罗罗非鱼、莫桑比克罗非鱼为星洲银罗非鱼的父母本。     

金—银系列矿物的电子探针定量分析方法及其应用

自然界最常见的金矿物是金-银系列矿物。作者利用电子探针显微分析仪,对我国的金-银系列矿物进行研究,取得了较好的效果。本文着重介绍电子探针定量分析方法和对50个样品的研究成果。样品分别取自我国各主要产金区的不同类型金矿床。研究结果表明,金-银系列的各亚种矿物在我国均有产出,金的含量由98.18％至微量。自然银和金银矿较为少见,自然金和银金矿则是最主要的工业矿物,几乎每个金矿床的样品中都普遍存在,不同类型的样品,金矿物所含的微量元素也有差异。     

花染色体组型分析及细胞核DNA含量的测定

采用PHA、秋水仙碱腹腔或背部肌肉注射,活体培养法,取花肾细胞制成悬浮液,用空气干燥法制片。经Giemsa染色,镜检细胞分裂相,统计结果为2n=50,核型公式为:2n=20m+12sm+10st+8t,NF=82。同时,取花肌肉和肝脏为材料,以鸡血细胞为DNA标准(2.30pg/2c),使用EPICS-XL型流式细胞仪测定了花细胞DNA含量,分别为2.219±0.055pg/2c和2.214±0.083pg/2c。     

Potential Orthopyroxene,Clinopyroxene and Olivine Reference Materials for In Situ Lithium Isotope Determination

Over 1400 electron probe and 700 ion probe microanalyses were performed on eleven mineral separates to evaluate their potential as reference materials for in situ Li isotopic determination. Our results suggest the homogenous distributions of major elements, Li and its isotopes for each sample. Hence, these samples are suitable to be used as reference materials for in situ measurements of Li abundance and Li isotopes by secondary ion mass spectrometry (SIMS) or laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS). These samples have the advantage of mitigating probable matrix effects during calibration owing to the wide range of compositions. The effect of composition on the δ⁷Li of olivine measured by SIMS is a linear function of composition, with δ⁷Li increasing by 1.0‰ for each mole per cent decrease in forsterite component.