193 resultados para 12S rRNA
Resumo:
Partial sequences of mitochondrial 16S rRNA gene were obtained by PCR amplification for comparisons among nine species of glyptosternoid fishes and six species of non-glyptosternoids representing 10 sisorid genera. There are compositional biases in the A-rich impaired regions and G-rich paired regions. A-G transitions are primarily responsible for the Ts/Tv bias in impaired regions. The overall substitution rate in impaired regions is almost two times higher than that in the paired regions. Saturation plots at comparable levels of sequence divergence demonstrate no saturation effects. Phylogenetic analyses using both maximum likelihood and Bayesian methods support the monophyly of Sisoridae. Chinese sisorid catfishes are composed of two major lineages, one represented by (Gagata (Bagarius, Glyptothorax)) and the other by "glyptosternoids + Pseudecheneis". The glyptosternoids may not be a monophyletic group. A previous hypothesis referring to Pseudecheneis as the sister group of monophyletic glyptosternoids, based on morphological evidence, is not supported by the molecular data. Pseudecheneis is shown to be a sister taxon of Glaridoglanis. Pareuchiloglanis might be paraphyletic with Pseudexostoma and Euchiloglanis. Our results also support the hypothesis that Pareuchiloglanis anteanalis might be considered as the synonyms of Pareuchiloglanis sinensis, and genus Euchiloglanis might have only one valid species, Euchiloglanis davidi.
Resumo:
The phylogenetic relationships among peritrichs remain unresolved. In this study, the complete small subunit rRNA (SSrRNA) gene sequences of seven species (Epistylis galea, Campanella umbellaria, Carchesium polypinum, Zoothamnium arbuscula, Vaginicola crystallina, Ophrydium versatile, and Opercularia microdiscum) were determined. Trees were constructed using distance-matrix, maximum-likelihood and maximum-parsimony methods, all of which strongly supported the monophyly of the subclass Peritrichia. Within the peritrichs, 1) E. galea grouped with Opercularia microdiscum and Campanella umbellaria but not the other Epistylis species, which indicates that the genus Epistylis might not be monophyletic; 2) the topological position of Carchesium and Campanella suggested that Carchesium should be placed in the family Zoothammidae, or be elevated to a higher taxonomic rank, and that Campanella should be independent of the family Epistylididae, and probably be given a new rank; and 3) Opisthonecta grouped strongly with Asty/ozoon, which suggested that Opisthonecta species were not the ancestors of the stalked peritrichs.
Resumo:
This study presents partial mitochondrial 16S rRNA sequences of 13 unionid bivalve species from China and analyses their relationships in combination with known data of 21 American mussels. According to our results, Chinese unionids, formerly regarded as two subfamilies, should be divided into three subfamilies: Ambleminae, Anodontinae and Unioninae. The genera Hyriopsis, Solenaia, Lamprotula and Ptychorhynchus, hitherto placed in Unioninae or Anodontinae, should be moved to the subfamily Ambleminae, demonstrated for the first time from China. The other genera recorded from China are suggested to belong to Anodontinae and Unioninae, which is in agreement with traditional classifications, except for the genus Lepidodesma.
Resumo:
The peritrichs have been recognized as a higher taxon of ciliates since 1968. However, the phylogenetic relationships among them are still unsettled, and their placement within the class Oligohymenophorea has only been supported by the analysis of the small subunit rRNA gene sequence of Opisthonecta henneguyi. DNA was isolated directly from field-sampled species for PCR, and was used to resolve relationships within the genus Epistylis and to confirm the stability of the placement of peritrichs. Small subunit rRNA gene sequences of Epistylis plicatilis, Epistylis urceolata, Epistylis chysemydis, Epistylis hentscheli, Epistylis wenrichi, and Vorticella campanula were sequenced and analyzed using both distance-matrix and maximum-parsimony methods. In phylogenetic trees, the monophyly of both the genus Epistylis and the subclass Peritrichia was strongly supported, while V. campanula clustered with Vorticella microstoma. The topology in which E. plicatilis and E. hentscheli formed a strongly supported sister clade to E. urceolata, E. chrysemydis, and E. wenrichi was consistent with variations in the thickness of the peristomial lip. We concluded that the peristomial area, especially the. peristomial lip, might be the important phylogenetic character within the genus Epistylis.
Resumo:
The taxonomy of Aphanizomenon flos-aquae strain NH-5, a producer of cyanotoxins, was re-evaluated by comparison with six other Aphanizomenon strains using morphological characteristics and 16S rRNA gene sequences. Strain NH-5 was concluded to be improperly identified as Aph. flos-aquae based upon (1) lack of bundle formation in the trichomes, (2) location of akinetes next to heterocytes, (3) lower similarities (less than 97.5%) in the 16S rRNA gene sequences relative to Aph. flos-aquae strains, and (4) comparison within a phylogenetic tree constructed from 16S rRNA gene sequences. The Aphanizomenon strains investigated in this study are classified to four morphological groups as described by the classical taxonomy of Komarek & Kovacik (1989). This classification was supported from the phylogenetic results of 16S rRNA gene sequences. This study also discusses the generic boundaries between Aphanizomenon and Anabaena.
Resumo:
We describe a new molecular approach to analyzing the genetic diversity of complex microbial populations. This technique is based on the separation of polymerase chain reaction-amplified fragments of genes coding for 16S rRNA, all the same length, by denaturing gradient gel electrophoresis (DGGE). DGGE analysis of different microbial communities demonstrated the presence of up to 10 distinguishable bands in the separation pattern, which were most likely derived from as many different species constituting these populations, and thereby generated a DGGE profile of the populations. We showed that it is possible to identify constituents which represent only 1% of the total population. With an oligonucleotide probe specific for the V3 region of 16S rRNA of sulfate-reducing bacteria, particular DNA fragments from some of the microbial populations could be identified by hybridization analysis. Analysis of the genomic DNA from a bacterial biofilm grown under aerobic conditions suggests that sulfate-reducing bacteria, despite their anaerobicity, were present in this environment. The results we obtained demonstrate that this technique will contribute to our understanding of the genetic diversity of uncharacterized microbial populations.
Resumo:
Heterosigma akashiwo (Hada) is a fragile, fish-killing alga. Efforts to understand and prevent blooms due to this harmful species to mitigate the impact on aquaculture require the development of methods for rapid and precise identification and quantification, so that adequate warning of a harmful algal bloom may be given. Here, we report the development and application of rRNA and rDNA-targeted oligonucleotide probes for fluorescence in situ hybridization (FISH) to aid in the detection and enumeration of H. akashiwo. The designed probes were species specific, showing no cross-reactivity with four common HAB causative species: Prorocentrum micans Ehrenberg, P. minimum (Pavillard) Schiller, Alexandrium tarmarense (Lebour) Balech, and Skeletonema costatum (Greville) Cleve, or with four other microalgae, including Gymnodinium sp. Stein, Platy-monas cordiformis (Karter) Korsch, Skeletonema sp.1 Greville and Skeletonema sp.2. The rRNA-targeted probe hybridized to cytoplasmic rRNA, showing strong green fluorescence throughout the whole cell, while cells labeled by rDNA-targeted probe exhibited exclusively fluorescent nucleus. The detection protocols were optimized and could be completed within an hour. For rRNA and rDNA probes, about a corresponding 80% and 70% of targeted cells could be identified and quantified during the whole growth circle, despite the inapparent variability in the average probe reactivity. The established FISH was proved promising for specific, rapid, precise, and quantitative detection of H. akashiwo. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
Although the deep-sea sediments harbor diverse and novel bacteria with important ecological and environmental functions, a comprehensive view of their community characteristics is still lacking, considering the vast area and volume of the deep-sea sedimentary environments. Sediment bacteria vertical distribution and community structure were studied of the E272 site in the East Pacific Ocean with the molecular methods of 16S rRNA gene T-RFLP (terminal restriction fragment length polymorphism) and clone library analyses. Layered distribution of the bacterial assemblages was detected by both methods, indicating that the shallow sediments (40 cm in depth) harbored a diverse and distinct bacterial composition with fine-scale spatial heterogeneity. Substantial bacterial diversity was detected and nine major bacterial lineages were obtained, including Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Nitrospirae, Planctomycetes, Proteobacteria, and the candidate divisions OP8 and TM6. Three subdivisions of the Proteobacteria presented in our libraries, including the alpha-, gamma- and delta-Proteobacteria. Most of our sequences have low similarity with known bacterial 16S rRNA genes, indicating that these sequences may represent as-yet-uncultivated novel bacteria. Most of our sequences were related to the GenBank nearest neighboring sequences retrieved from marine sediments, especially from deep-sea methane seep, gas hydrate or mud volcano environments. Several sequences were related to the sequences recovered from the deep-sea hydrothermal vent or basalt glasses-bearing sediments, indicating that our deep-sea sampling site might be influenced to certain degree by the nearby hydrothermal field of the East Pacific Rise at 13A degrees N.
Chromosomal rearrangement in Pectinidae revealed by rRNA loci and implications for bivalve evolution
Resumo:
Karyotype and chromosomal localization of major (18-5.8-28S) and minor (5S) ribosomal RNA genes were studied in two species of Pectinidae, zhikong (Chlamys farreri) and bay (Argopecten irradians irradians) scallops. using fluorescence in situ hybridization (FISH). C. farreri had a haploid number of 19 with a karyotype of 3m + 4sm + 7sm-st + 4st + 1st-t, and A. i. irradians had a haploid number of 16 with a karyotype of 5st + 11t. In C. farreri, the major and minor rRNA genes had one locus each and were mapped to the same chromosome-Chromosome 5. In A. i. irradians, the major rRNA genes had two loci, located on Chromosomes 4 and 8, and the 5S rRNA gene was found at a third chromosome-Chromosome 10. Results of this and other studies indicate that karyotype of A. i. irradians (n = 16, 21 arms) is secondary and derived from an ancestral karyotype similar to that of C. farreri (n = 19, 38 arms) through considerable chromosomal loss and rearrangements. The ability to tolerate significant chromosomal loss suggests that the modal karyotype of Pectinidae and possibly other bivalves with a haploid number of 19 is likely tetraploid; i.e., at least one genome duplication has occurred during the evolution of Bivalvia.
Resumo:
Karyotype and chromosomal location of the major ribosomal RNA genes were studied in the hard clam (Mercenaria mercenaria Linnaeus) using fluorescence in situ hybridization (FISH). Metaphase chromosomes were obtained from early embryos. Internal transcribed spacers (ITS) between major RNA genes were amplified and used as FISH probes. The probes were labeled with digoxigenin-11-dUTP by polymerase chain reaction and detected with fluorescein-labeled anti-digoxigenin antibodies. FISH with the ITS probes produced two to four signals per nucleus or metaphase. M. mercenaria had a haploid number of 19 chromosomes with a karyotype of seven metacentric, four metacentric or submetacentric, seven submetacentric, and one submetacentric or subtelocentric chromosomes (7M + 4M/SM + 7SM + 1SM/ST). Two ITS loci were observed: one located near the centromere on the long arm of Chromosome 10 and the other at the telomere of the short arm of Chromosome 12. FISH signals on Chromosome 10 are strong and consistent, while signals on Chromosome 12 are variable. This study provides the first karyotype and chromosomal assignment of the major RNA genes in M. mercenaria. Similar studies in a wide range of species are needed to understand the role of chromosomal changes in bivalve evolution.
Resumo:
Molecular diagnosis is playing an increasingly important role in the rapid detection and identification of pathogenic organisms in clinical samples. The genetic variation of ribosomal genes in bacteria offers an alternative to culturing for the detection and identification of these organisms. Here 16S rRNA and 16S-23S rRNA spacer region genes were chosen as the amplified targets for single-strand conformation polymorphism (SSCP) and restriction fragment length polymorphism (RFLP) capillary electrophoresis analysis and bacterial identification. The multiple fluorescence based SSCP method for the 16S rRNA gene and the RFLP method for the 16S-23S rRNA spacer region gene were developed and applied to the identification of pathogenic bacteria in clinical samples, in which home-made short-chained linear polyacrylamide (LPA) was used as a sieving matrix; a higher sieving capability and shorter analysis time were achieved than with a commercial sieving matrix because of the simplified template preparation procedure. A set of 270 pathogenic bacteria representing 34 species in 14 genera were analyzed, and a total of 34 unique SSCP patterns representing 34 different pathogenic bacterial species were determined. Based on the use of machine code to represent peak patterns developed in this paper, the identification of bacterial species becomes much easier.
Resumo:
本文对斜角铺层碳/环氧复合材料层板([0°]_(48′)[±30°]_(12s′)[±45°]_(12s′)[±60°]_(12s′)[90°]_(48))的压缩破坏进行了实验研究,实验结果包括压缩强度,层板破坏模式和破坏机理。对所研究的层板,其破坏模式为层间剪切破坏([0°]_(48′)[±30°]_(12s)试件),纤维剪变([±45°]_(12s)试件),面内基体剪切破坏及基体压缩破坏([±60°]_(12s′)[90°]_(48)试件)。
Resumo:
本文采用来自三个基因组——叶绿体、线粒体和核基因组的六个DNA序列片段,对壳斗目的系统发育进行了重建,主要探讨了壳斗目八个科的科间系统演化关系及不同基因系统树间存在冲突的原因。在此基础上针对具体问题,进一步选用核光敏色素PHYC基因序列对杨梅科在壳斗目中的系统位置进行了更深入的探讨。在对壳斗目开展大量分子系统学研究的同时,还对胡桃科化香树属Platycarya的花形态发生过程进行了详细的扫描电镜观察,讨论了胡桃科单性花的起源和演化问题。主要内容包括: 1 基于四个叶绿体DNA序列的分析 以金缕梅属Hamamelis 和朴树属Celtis 为外类群,对壳斗目几乎所有属的代表共31种植物的trnL-F、matK、rbcL和atpB 序列进行了测定,通过四个序列单独和联合分析,得到如下结果:除rbcL基因树由于信息位点少而分辨率较低之外,壳斗目各科作为单系类群在各种分析中都得到了较强的bootstrap(BS)支持。壳斗目的八个科分为三支:南青冈科Nothofagaceae是基部分支;壳斗科Fagaceae接着分出;核心高等金缕梅类 (core “higher” hamamelids) 聚为一支, 这三支也都得到了强支持。基于不同序列构建的系统发育树,主要区别在于对核心高等金缕梅类六个科,即第三支内部分支关系分辨的不同。在trnL-F树上核心高等金缕梅类又分成两个亚支,一亚支是木麻黄科Casuarinaceae-(桦木科Betulaceae-核果桦科Ticodendraceae),另一亚支是杨梅科Myricaceae-(胡桃科Juglandaceae-马尾树科Rhoipteleaceae);matK树上,杨梅科则与前一亚支,即木麻黄科和桦木科聚在了一起;atpB树上杨梅科又成了其他所有核心高等金缕梅类的姐妹群;基于四序列联合分析构建的系统发育树的拓扑结构基本上与matK基因树一致。胡桃科和马尾树科的亲缘关系在对不同序列的分析中都得到了较强的支持,但对杨梅科的聚类,支持率都很弱。 2 基于线粒体matR基因序列的分析 除南青冈科作为其他所有壳斗目类群的姐妹群得到强支持外,其余的壳斗目的科间系统发育关系都未得到很好的分辨。最简约树的严格一致树显示杨梅科和木麻黄科聚在一起得到的BS支持不强,另外桦木科和核果桦科,壳斗科和马尾树科分别聚在一起,但得到的支持都未超过50%。 3 基于核核糖体18S rDNA序列的分析 在18S rRNA基因最简约树的严格一致树上,壳斗目被分为两支,一支由壳斗科和南青冈科组成,另一支由核心高等金缕梅类组成,BS支持率均不高。核心高等金缕梅类又分成两个亚支,桦木科,核果桦科和木麻黄科组成的亚支得到了较强的支持,由胡桃科、马尾树科和杨梅科组成的另一亚支得到了更强的BS支持。胡桃科和桦木科的单系性都得到了分辨,虽然BS支持率不高。 4 六个DNA序列的联合分析 通过对六个DNA序列的单独和联合分析,探讨了引起基因树间拓扑结构冲突的可能原因。分别用MP法、NJ法和贝叶斯推论对壳斗目进行了系统发育重建,联合分析提供了分辨率最好、支持率最高的壳斗目谱系关系图: 1、 南青冈科是壳斗目其余类群的姐妹群;2、各科的单系性得到很好支持;3、壳斗科是核心高等金缕梅类的姐妹群;4、核心高等金缕梅类分为两个亚支,一亚支包含桦木科、核果桦科和木麻黄科;另一亚支由胡桃科、马尾树科和杨梅科组成,杨梅科是胡桃科和马尾树科的姐妹群,这一亚支的BS支持率仍然很弱。胡桃科和壳斗科的属间关系未得到很好分辨,多数分支的BS支持率和后验概率值都不高。 5 基于核PHYC基因序列证据对杨梅科系统位置的分析 用壳斗科的栎属Quercus和南青冈科的南青冈属Nothofagus做外类群,核心高等金缕梅类分为两支。桦木科和木麻黄科聚在一起,胡桃科和马尾树科为姐妹群再与杨梅科构成一支,这两个分支都得到很强的BS支持。核基因分析支持六个序列联合分析对核心高等金缕梅类各科间关系的分辨。 6 化香树的花器官发生 在扫描电镜下系统地研究了柔荑花序类植物化香树的雄花、雌花和两性花的发生和发育过程。结果表明:该植物雄花和两性花中小苞片和花被片缺乏;雄蕊轮状发生,成熟阶段雄蕊的不规则排列是由于花托的延伸且和苞片的基部融合后造成的;雌花中存在环状的花被片结构但极度退化,雌花两侧的小苞片和花被片的侧面部分构成小坚果的翅;化香树的两性花向心发生,雄蕊先发生,然后雌蕊发生。胡桃科中的单性花是由两性花退化而来。 本研究的主要发现和结论如下: 1第一次用来自不同基因组的多个DNA 序列探讨了壳斗目八科的系统发育关系;取样包括了所有科的几乎所有的属;所得到的系统树具有较高的分辨率和置信度。主要结论是壳斗目的八个科分为三支,南青冈科是最基部的分支,壳斗科做为核心高等金缕梅类的姐妹群第二个分出,核心高等金缕梅类聚在一起,并进一步分为两个亚支:第一亚支包括桦木科、核果桦科和木麻黄科;另一亚支则由胡桃科、马尾树科和杨梅科组成,杨梅科是胡桃科和马尾树科的姐妹群。 2用核光敏色素PHYC基因较好的解决了杨梅科的系统位置,尽管造成杨梅科在叶绿体基因树和核基因树上具有不同系统位置的原因尚需要进一步探讨。在PHYC基因树上桦木科和木麻黄科聚在一起,胡桃科和马尾树科为姐妹群再与杨梅科构成一支,这两个分支都得到很强的支持。 3首次在壳斗目植物中用扫描电镜观察到了雄花的发生过程和两性花的发生方式,澄清了在化香树属植物中关于雄蕊排列方式、花被式样、以及果翅来源等问题的疑惑或争论。
Resumo:
核核糖体DNA(nrDNA)已被作为一个重要的标记,用于推断很多分类等级上的系统发育关系。相对于在被子植物中的快速致同进化,nrDNA在裸子植物中的致同进化速率低,且ITS和5S-NTS区有着较大的长度变异,这种现象在松科植物中尤为明显。在本研究中,我们克隆并测定了银杉属的5S rDNA以及冷杉属、银杉属、雪松属、油杉属、长苞铁杉属、金钱松属与铁杉属的ITS序列。基于获得的新数据,再结合前人报导的其它属的数据,我们探讨了如下四个问题: (1)松科 nrDNA ITS1 亚重复单位的组成、分布及进化;(2)ITS1区的长度变异与亚重复单位数目的关系以及它们的系统学意义;(3)松科ITS1的二级结构特征;(4)银杉5S rDNA编码区及非转录间隔区的结构特征。主要研究结果如下: 1. ITS区的序列分析ITS区的克隆及序列分析发现:(1) 松科ITS1的长度变异范围为 944-3271 bp, 这是目前已报导的真核生物中属间ITS变异最大的类群之一;(2) 所有松科植物的ITS区域都包含亚重复单位,亚重复单位的数目从2到9,并且这些亚重复单位可分为两种类型,即不含保守核心序列(5’-GGCCACCCTAGTC ) 的长亚重复单位(LSR)和含上述保守核心序列的短亚重复单位(SSR);(3) ITS1区的巨大长度变异主要归因于亚重复单位的数量变异; (4) ITS1区的GC含量与 它的序列长度和亚重复单位的数目有一定关系,并能够提供一些系统发育信息,特别是支持云杉属、松属和银杉属三者具有很近的亲缘关系。 2. ITS1亚重复单位的系统发育分析为了研究亚重复单位的进化关系,我们用最大似然法和最大简约法构建了松科ITS1亚重复单位的系统发育树。结果表明:(1)在ML和MP树中可发现有共同的五个分支; (2) 银杉比松科其它属拥有更多的SSR,且该属的所有9个SSR在系统树中构成一个单系支,表明它们是在银杉属内发生重复的;(3)一些SSR在属间和种间具有同源性,可为nrDNA ITS 的进化历史以及松科的系统发育 研究提供重要信息;(4)亚重复单位的多次重复以及伴随的重组可能是导致LSR 和SSR在松科不同属中分布式样不同的原因。 3. 松科ITS1的二级结构 用 Mfold 3.2 软件对松科所有11个属的ITS1区进行了二级结构预测,共获得了563个最低自由能折叠。结合以前关于松科二级结构的报导,我们分析的结果表明:(1) 松科ITS1的二级结构主要由几个延展的发夹结构组成;(2) 构象的复杂性与亚重复的数目呈正相关;(3)配对的亚重复单位通常在保守核心区(5’-GGCCACCCTAGTC ) 处有部分重叠,并且构成一个长茎,而其它的亚重复单位通常会自身折叠,且保守核心区的部分出现在发夹结构的环中。 4. 银杉5S rDNA 序列分析 我们对来自银杉不同群体的3个个体的5S rDNA进行了克隆,共获得 45 条序列,分析结果表明:(1) 绝大多数银杉5S rDNA编码区长度为120 bp, 以GGG 开头,以CTC结尾,编码区出现的碱基替代主要为转换;(2) 银杉与其它裸子植物相比,5S rDNA基因编码区具很高的相似性(90-99%); (3)间隔区含有一个poly-C和一个poly-T结构、两个TC丰富区以及五个GC丰富区。根据长度和序列特征,银杉的5S rDNA间隔区可分为三种类型:Type A 长751-764 bp,Type B 长770-807 bp (含一个32 bp的插入),Type C 长581-594 bp; (5)长间隔区(Type A,Type B )中含有两个148-175 bp的串联亚重复单位,该亚重复单位与短间隔区(Type C )中的一段143 bp的序列具有较高的相似性(56.0-66.8%)。 5. 银杉5S rRNA的二级结构 Mfold 3.2 预测结果表明:(1)银杉5S rRNA二级结构包括5个双螺旋区(干区)(Ⅰ-Ⅴ)、2个发夹结构环区(C和D)、3个中间环区(B1、B2 和 E)和1个铰链区(A), 铰链区为三个双螺旋的结合处;(2) 二级结构中的环区通常比双螺旋区更加保守;(3)在5个双螺旋中,I 和 IV 区有较高的碱基替代率。
Resumo:
利用RNA减法杂交、差异筛选和5’-RACE等方法从水稻分离到了一花药绒毡层特异表达的基因RA39。Southern 杂交表明,RA39在水稻基因组中是以单拷贝的形式存在的。RT-PCR 结果初步表明,RA39是一水稻花药特异表达的基因。RNA原位杂交进一步表明,RA39主要在水稻花药的绒毡层中表达,而且在小孢子母细胞减数分裂期和四分体时期表达量最高。RA39 cDNA全长1013bp,编码298个氨基酸残基。 RA39 cDNA与数据库中的已知序列没有明显的相似性,由其推测的多肽与核糖体失活蛋白(ribosome-inactivating protein, RIP)的序列相似在19-34%之间。多重序列排列分析结果表明构成RIPs活性位点的5个关键氨基酸残基在RA39中是保守的,在蓖麻毒蛋白中分别为Tyr80、 Tyr123、 Glu177、 Arg180 and Trp211 。利用原核表达系统,通过蛋白质分离和纯化获得了在SDS电泳图谱上为单一条带的纯的RA39蛋白,用兔rRNA作底物进行的酶活性分析证明该蛋白有N-糖基化作用,是一种类型I的核糖体失活蛋白。反义转基因植株的花粉用TTC进行活性染色结果显示其活性明显减弱,成熟的T0代反义转基因植株的结实率明显降低,只有对照的20-60%。这说明,RA39蛋白可能和小孢子母细胞的发育相关。 酵母DMC1是减数分裂过程中同源染色体配对和重组修复所必需的减数分裂特异基因。根据酵母Dmc1和拟南芥AtDmc1的保守区设计简并性引物,通过RT-PCR和RACE等方法,从水稻中分离出了酵母DMC1的同源基因OsDMC1。RT-PCR分析表明,OsDMC1在花中表达量最高,在根中表达量较低,在叶片和幼芽几乎不表达。水稻基因组中有两个拷贝的OsDMC1。OsDmc1蛋白与酵母Dmc1和拟南芥AtDmc1氨基酸一致性分别为53%和81%。 酵母Spo11在减数分裂过程中具有催化DNA双链断裂从而起始同源重组的功能。以酵母Spo11氨基酸序列为探针和现有的数据库通过数据分析,结合RACE技术,克隆了水稻SPO11同源基因OsSPO11-1, OsSPO11-1是一个单拷贝基因,有3个外显子和2个内含子,在转录过程中通过内含子的可变剪切产生4个不同的转录本(OsSPO11-1A、OsSPO11-1B、OsSPO11-1C和OsSPO11-1),其中,OsSPO11-1A是一个未剪切的转录本,OsSPO11-1B包含内含子2,OsSPO11-1C包含内含子1,OsSPO11-1D是一个完全剪切的转录本。这些转录本编码的蛋白有一致的246氨基酸残基的C-端,包含了Spo11/TopVIA家族蛋白共有的5个功能基元,是该家族的新成员。OsSPO11-1A和 OsSPO11-1C在花中优势积累,OsSPO11-1B是花特异的,而OsSPO11-1D在营养器官中优势积累。在花中该基因主要在减数分裂的花粉母细胞和胚曩中表达,在减数分裂期的绒毡层细胞和不同花器官的微管束细胞中也表达。这些结果说明内含子涉及到了OsSPO11-1表达的器官特异性调节,该基因除了参与减数分裂的调节外,在体细胞的发育中可能起重要作用。