METTL21C蛋白的序列特征、三维结构及分子进化

METTL21C蛋白作为甲基转移酶参与多种细胞进程的翻译后修饰,在生命活动中发挥重要的调控作用。从蛋白质信息数据库UniprotKB中选取36个不同代表物种的METTL21C蛋白作为研究对象,理化参数分析显示一级序列中氨基酸残基个数差异较大,平均为254个氨基酸残基,大多为偏酸亲水性蛋白。系统进化树显示36种METTL21C蛋白共分为哺乳类、爬行类、鸟类和鱼类4支,与物种的亲缘进化关系基本吻合。多序列比对和motif分析结果表明不同物种METTL21C蛋白的序列相似度较高,10个motif序列几乎覆盖了全长多肽链,大都含有motif 1～motif 5,但N端序列差异较大,在哺乳动物中包含特有的motif 7、motif 8和motif 10,而在多种鸟类中有大段序列缺失。结构对比分析发现不同物种METTL21C蛋白的空间构象绝大部分区域近乎完全重叠,仅少部分自由度较高的局部肽段有一定程度的差异,表明不同物种METTL21C在进化过程中一级序列有一定的差异,但是空间结构极为相似。以人METTL21C为蛋白质互作网络中心,直接相关蛋白质共11种,间接相关蛋白质共9种,说明METTL21C直接或间接参与多种细胞进程,调控机体的生命活动,为进一步深入研究METTL21C的生物学功能及其分子机制提供了理论基础。     

小麦BES1转录因子全基因组鉴定与分析

为了解小麦中 BES1基因家族功能,根据已公布的小麦基因组信息(IWGSC v1.1),对小麦 BES1基因家族进行全基因组鉴定。根据已报道的 BES1基因,采用同源比对法检索小麦基因组中的 BES1家族基因,pfam鉴定并进行编号,通过ExPASy Proteomics Server预测小麦 BES1氨基酸序列的基本信息,利用Cell-PLoc进行亚细胞定位预测,采用MEGA 7软件构建进化树,利用R软件包pheatmap绘制启动子的热图和circlize绘制同源关系图谱。结果表明,小麦共有15个 BES1基因,被分为4组;小麦 BES1编码的蛋白质等电点为8.13～9.4,不稳定指数为50.78～69.99;小麦 BES1启动子区域一共含有838个顺式元件,471(56.2%)个与生长发育有关,201(24%)个与非生物/生物胁迫有关,166(19.8%)个与激素反应有关;与普通小麦相关的同源物共52对,有13对(25%)旁系同源物和39对(75%)直系同源物。表明小麦 BES1基因家族包括15个成员,全部为碱性蛋白质和不稳定蛋白质,小部分(13对25%)来源于自身的进化,大部分(39对75%)来源于3种亚基因组供体小麦。     

南沙群岛重点岛礁潟湖微型浮游动物的群落结构与摄食

潟湖是岛礁生物多样性演变的重要环境场,在岛礁水生态系统的物质循环和能量流动中发挥重要作用,而微型浮游动物的生态功能研究是解析南沙群岛岛礁水域潟湖生态系统初级生产力组成、流向、能量流动效率的重要研究内容之一。实验通过对南沙群岛重点岛礁渚碧礁、美济礁与永暑礁潟湖表层水域中微型浮游动物与生态环境调查,研究了其群落结构及其与环境因子的关系,并通过稀释培养实验研究了微型浮游动物的摄食压力。结果显示,调查水域共发现微型浮游动物20种,总丰度的范围为320～1 460个/L,以无壳纤毛虫丰度最高。无壳纤毛虫在渚碧礁潟湖西部水域（ZB-1）丰度最高,砂壳纤毛虫峰值则出现在永暑礁潟湖中部水域（YS-3）,桡足类幼体丰度最大值出现在美济礁潟湖北部水域（MJ-2）。聚类分析结果显示,3个岛礁潟湖中部区域的微型浮游动物群落相似度较高,溶解氧是影响群落结构的最重要因素,特别是对MJ-3站位影响最为突出。摄食实验结果显示,3个岛礁潟湖水域浮游植物生长率为0.22～1.36 d^-1;微型浮游动物摄食率范围为0.22～0.60 d^-1,微型浮游动物每天约摄食浮游植物现存量的...     

关于贝类遗传改良几个问题的讨论

贝类大多为雌雄异体，少数种类是雌雄同体，在雌雄异体的种类也有部分个体表现为雌雄同体，而且雌雄异体型贝类还常有性转变现象。养殖贝类大多行体外受精并具有配子量大、子裔数量多等特点。野生型贝类表型方差大，遗传变异水平高。可见，贝类是一群比较独特的动物，其生殖方面的某些特性与作物的共同点甚至超过与高等动物的共同点。因此仅依靠脊椎动物或植物的育种方法，难以解决好贝类的种质改良问题。     

Karyotype analysis of Oreochromis mortimeri (Trewavas) and Sarotherodon melanotheron (Rüppell)

The karyotypes of both Oreochromis mortimeri (Trewavas) and Sarotherodon melanotheron (Rüppell) are shown to consist of 22 pairs of chromosomes (2n = 44). In O. mortimeri, the karyotype is composed of 9 sm/st and 13 t chromosomes. In the case of S. melanotheron, the karyotype is composed of 15 sm/st, 2 m and 5 t chromosomes. The karyotypes of these species are therefore similar to those of the majority of other tilapia species, with that of S. melanotheron being considerably different from that previously reported for this species.     

Molecular cloning of the cDNA encoding the β subunit of thyrotropin and regulation of its gene expression by thyroid hormones in the goldfish, Carassius auratus

A cDNA encoding the subunit of thyrotropin (TSH) was isolated from a goldfish (Carassius auratus) pituitary gland cDNA library. By comparing the sequence with other teleost TSHs, a signal peptide of 19 amino acids and a mature hormone of 131 amino acids were predicted for goldfish TSH subunits. The resulting putative mature hormone of 131 amino acids had well-conserved cysteine positions and a putative N-linked glycosylation site; homology was 51–67% with TSHs from other teleosts, 38–43% with tetrapod TSHs, but only 27 and 29% with goldfish GTH-I and -II, respectively. We also examined the effects of thyroid hormones (TH) and thiourea (TU, an inhibitor of TH production) treatments on TSH and GTH subunit gene expressions in the goldfish pituitary gland. After thyroxine (T₄) treatment, circulating T₄ concentration increased and TSH mRNA level decreased. Supressing the amount of circulating T₄ and triiodothyronine (T₃) by TU treatment increased the TSH mRNA level. Moreover, T₄ replacement therapy (simultaneous treatment of both TU and T₄) caused a high level of circulating T₄ and a low level of circulating T₃, and a decrease in the TSH mRNA level. Thus, changing levels of circulating TH exert a negative feedback on the level of TSH subunit mRNA in goldfish in vivo. On the other hand, GTH subunit mRNA levels were not affected by changes in the levels of circulating TH.     

Fragmentation patterns and systematic transitions of the forested landscape in the upper Amazon region,Ecuador 1990–2008

The analysis of the systematic transitions in the forested landscape and the study of the forest fragmentation patterns allow us to deepen our understanding of the changes in the vegetation ground cover. The importance of knowing the intricate patterns of the land usage of the upper basin of the Amazon region is widely recognized. This zone is one of the most diverse biological areas in the world, is home to large areas of mature tropical cloud forest and demonstrates high probabilities of stable climatic conditions in light of global warming. The research quan- tiffed systematic transitions through the ＂loss＂ and ＂gain＂ of the different categories of landscape during the eighteen-year study period of the Ecuadorian Amazon Region （EAR）, the forest fragmentation patterns were also analyzed based on a set of indicators. Therefore, with respect to the entirety of the landscape, the results registered for the ground coverage in forested areas during the first period （1990-2000）, show a decrease of 6.99% and an increase of 0.68%; and during the second period （2000-2008）, show a decrease of 3.99% and an increase of 2.14%. It demonstrated that forest and agricultural areas tended to replace or be replaced by herbaceous vegetation faster than expected fortuitously. Finally, the indices of fragmentation signaled intense changes during the 1990-2000 period with a reduction during the period 2000-2008. Per- centages registered in the Largest Patch Index （LPI） were between 79.58%; 52.39% and 49.99% respectively; while the Patch Density （PD） varied between 0.04; 0.06 and 0.07. This suggests the propensity of for- est cover to remain intact. The results of this investigation suggest a tendency towards stability in Ecuador＇s Amazon landscape. Within the framework for development and management of this area, the tendency is natural regeneration. This permits a consolidation of the conservation, reforestation, forestation and agricultural forestry plans, programs and systems for the protected areas in EAR.     

甘蔗的起源和进化

文章通过总结近20年来有关甘蔗属分类、地理起源、栽培起源与传播、甘蔗进化以及甘蔗基因组进化等的研究结果,全面分析了甘蔗的起源和进化进程,分析结果支持Brandes于1958年提出的假说。建议今后应对割手密种、大茎野生种和热带种之间的相互关系展开深入研究,以便更全面了解甘蔗的起源和进化;同时应开展甘蔗全基因组测序研究、甘蔗叶绿体基因组学研究及构建甘蔗遗传连锁图谱,全面深入剖析甘蔗的遗传结构和驯化进程。     

甘蔗多样性微阵列技术（DArT）标记体系的建立

[目的]建立成熟、稳定的甘蔗多样性微阵列技术（Diversity array technology,DArT）标记体系,为甘蔗的遗传多样性分析、遗传图谱构建及标记辅助育种等提供新的分子标记方法.[方法]以7份不同种属的甘蔗材料为样本,优化基因组复杂性降低方法并建立甘蔗DArT标记体系,同时应用该体系分析7份材料的遗传多样性.[结果]获得了基于PstⅠ/TaqⅠ酶切组合的最优基因组复杂性降低方法,利用该方法建立了DArT体系.利用DArT体系分析了7份材料之间遗传进化关系,发现供试7份材料的遗传相似系数为0.497～0.811,平均值为0.569.以遗传相似系数0.546为阀值,可以将供试材料分为三大类,其中第一类的GT29号、拔地拉和割手密GXS85-30均为甘蔗属材料,与预期相一致;第二类为河八王2号和滇蔗茅2号,第三类为芒84-8和斑茅GXA87-36.[结论]建立的甘蔗DArT标记体系具有有效性,其遗传相似性分析结果与材料预期的亲缘关系密切程度相一致.     

Evolutionary implications of two rainbow trout growth hormone genes

The primary structures of two rainbow trout growth hormone mRNAs (GH1 and GH2) have been deduced by direct sequencing of their respective cDNA clones and portions of the mRNA. Both GH1 and GH2 mRNA contain open reading frames comprised of 630 nucleotides and encode 210 amino acid residues of which 11 are variant. The translated regions of both mRNA are flanked by a short but rather conserved 5′-end, and a relatively long but highly diverged 3′-end. The differences at translated and 3′-untranslated regions suggest that the GH1 and GH2 mRNA originate from different loci. The GH1 and GH2 mRNA are likely transcribed from two distinct loci which were duplicated during tetraploidization of salmonid genome between 50 to 100 million years ago. The GH2 gene has been isolated and sequenced from a rainbow trout genomic library. This gene spans a region of approximately 4 kilobases. The trout GH gene is comprised of 6 exons and 5 introns, in contrast to 5 exons and 4 introns in mammals. The additional intron in the trout gene interrupts the translated regions that are analogous to the last exon of the mammalian counterpart. The alleged internally repeating sequences in mammalian GH, prolactin (Pr1) and placental lactogen (PL) are not observed in the predicted polypeptide sequence of trout GH. In addition, direct repeats that flank exons I, III and V of mammalian GH, Pr1 and PL genes are absent in trout gene. These findings indicate that the rainbow trout GH gene structure does not support the current hypothesis that internally repeated regions in GH, Pr1 and PL arose from a small primordial gene.