草鱼MyD88基因组结构解析及启动子活性探讨

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两种鱼类Sox基因保守区的克隆和Sox9基因保守区内含子的遗传变异性

Sox基因家族是生物个体发育过程中关键的调控因子,尤其在睾丸、神经、肌肉和骨骼等组织分化和发育过程中发挥着重要的作用(Fosteretal.,1 994 ;PevnyandLovell Badge ,1 997;Schepersetal.,2 0 0 0 ;ClarksonandHarley ,2 0 0 2 ;Changetal.,2 0 0 2 ;Monteroetal.,2 0 0 2 ;Ga     

拟南芥和线虫基因序列及剪切位点的理论预测

将拟南芥(A．thaliana)和线虫(C．elegans)基因组按外显子、内含子及基因间序列区分为3类。分别选取64、40、20种三联体的概率作为信号参数构建离散源,根据离散增量预测序列所属类型。结果表明：拟南芥各条染色体标准集总预测成功率达到82．19％,检验集为87．95％;线虫各条染色体标准集总预测成功率达到79．67％,检验集达到81,93％。另外,将两种基因序列中的外显子分别划分成3类,用外显子剪切位点、翻译起始和结束位点附近的三联体的3个位点作为3条子链,以各条子链的12个参数构建离散源,用离散增量对3种序列类型进行预测,预测成功率都达80％以上。     

Species separation in <Emphasis Type="Italic">Curvularia</Emphasis> “geniculata” group inferred from <Emphasis Type="Italic">Brn1</Emphasis> gene sequences

 Brn1, a reductase gene involved in the melanin biosynthetic pathway, was adopted for species delimitation among members in the “geniculata” group of Curvularia species and proved to be useful for this purpose. Phylogenetic trees of these fungal members were constructed from nucleotide sequences of this region. The so-called geniculata group of Curvularia was separated into several clusters. The conidial morphology of the members in each cluster is closely similar but clearly different among discrete clusters. The phylogenetic groups almost concurred with the morphological grouping. Thus, the synonymous treatment of Curvularia affinis, C. fallax, and C. senegalensis to C. geniculata in a previous study was supported. The isolates with warping hilum conidia were clearly different from C. geniculata and separated into two clusters. C. geniculata ATCC 6671 made an independent cluster situated near these clusters. The protuberant hilum species were located separately in the phylogenetic trees. For sound taxonomic treatment of these isolates, we should accumulate more information and retain our species determination for them. Received: September 26, 2002 / Accepted: March 12, 2003     

内含子编码蛋白与内含子的转移

具有自我剪接能力的Ⅰ型和Ⅱ型内含子有编码蛋白质的功能。Ⅰ型内含子编码成熟酶和核酸内切酶,后者参与Ⅰ型内含子的归巢。Ⅱ型内含子编码的蛋白质呈现成熟酶核酸内切酶和逆转录酶活性,三种活性都在Ⅱ型内含子归巢中起作用。除归巢外,Ⅰ型和Ⅱ型内含子的转移还表现为转位和丢失。内含子作为可转移遗传因子,可能在进化中有一定的意义。     

Nodal基因的第一内含子中存在着顺式调控增强子元件

小鼠ｎｏｄａｌ基因是在胚胎发育时期表达的一个基因,它在原肠期起着重要作用,并且参与左－右体轴的决定,４１３－ｄ小鼠胚胎干细胞系３５６３在ｎｏｄａｌ基因的第一内含子中含有单拷贝逆转录病毒的插入。采用定量ＲＮａｓｅ保护法比较了该细胞系及其母源ＥＳ细胞ＣＣＥ中ｎｏｄａｌ基因的表达量,ＣＣＥ细胞中ｎｏｄａｌ ｍＲＮＡ的含量是３５６３ＥＳ细胞含量的２．３倍。这一结果提示原病毒在ｎｏｄａｌ基因第一内含子中的整     

The paradox of MHC-DRB exon/intron evolution: α-helix and β-sheet encoding regions diverge while hypervariable intronic simple repeats coevolve with β-sheet codons

Twenty-one different caprine and 13 ovine MHC-DRB exon 2 sequences were determined including part of the adjacent introns containing simple repetitive (gt)_n(ga)_m elements. The positions for highly polymorphic DRB amino acids vary slightly among ungulates and other mammals. From man and mouse to ungulates the basic (gt)_n(ga)_m structure is fixed in evolution for 7 × 10⁷ years whereas ample variations exist in the tandem (gt)_n and (ga)_m dinucleotides and especially their degenerated derivatives. Phylogenetic trees for the -helices and -pleated sheets of the ungulate DRB sequences suggest different evolutionary histories. In hoofed animals as well as in humans DRB -sheet encoding sequences and adjacent intronic repeats can be assembled into virtually identical groups suggesting coevolution of noncoding as well as coding DNA. In contrast a-helices and C-terminal parts of the first DRB domain evolve distinctly. In the absence of a defined mechanism causing specific, site-directed mutations, double-recombination or gene-conversion-like events would readily explain this fact. The role of the intronic simple (gt)_n(ga)_m repeat is discussed with respect to these genetic exchange mechanisms during evolution.     

动物肌动蛋白基因中内含子的来源及存在意义的探讨

对动物界演化过程中肌动蛋白家族内含子插入位置分布的演化规律作了分析,并对相同插入位置的内含子序列按同亚型和不同亚型作了比较。结果得出:从整个肌动蛋白家族的外显子序列高度保守性推断整个肌动蛋白家族可能是从共同的祖先蛋白进化而来的;从同亚型肌动蛋白内含子序列的类似性随进化距离而变化,但在短进化距离的物种间,类似性都较高,不同亚型肌动蛋白内含子序列的类似性都较低,即使是同一物种(如人),类似性也远低于同亚型但进化距离较近的物种,由此可推断,同亚型肌动蛋白的内含子序列可能从共同祖先进化,不同亚型肌动蛋白的内含子序列从不同祖先进化,综上推断可导出内含子可能是在蛋白异化过程中获得的:还发现内含子在肌动蛋白家族编码基因中位置的分布随进化方向不同而逐步形成两种截然不同的模式,由此提出了内含子的位置分布与动物演化方向之间可能具有某种必然联系,为内含子的存在提出了某种依据。