| 题名 | 贾第虫双核所含基因是否相同的证明与核型分析 |
| 作者 | 唐丹 |
| 学位类别 | 硕士 |
| 答辩日期 | 2011-11 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 文建凡 |
| 关键词 | 贾第虫 荧光原位杂交 基因转换 核型 |
| 其他题名 | Demonstration of Equal Gene Contents in the Two Nuclei of Giardia lamblia and the Karyotype Analysis |
| 学位专业 | 细胞生物学 |
| 中文摘要 | 蓝氏贾第鞭毛虫 (Giardia lamblia) 是一类寄生于人体小肠的低等单细胞原生动物。除了医学上的重要性，贾第虫还被认为是目前已知的最原始的真核细胞。它一个重要的特点是具有左右对称的两个细胞核，并且在形态和大小上都很相似。目前，关于贾第虫的双核，尽管有不少研究，但对它的两个核所含基因是否相同(如基因数目、基因种类等)，染色体数目是多少等等仍很不清楚。针对此，本文做了以下研究： 基于我们实验室之前对贾第虫基因转换所进行研究的基本情况：在贾第虫基因组中存在13个与基因转换相关的基因的同源物：spo11, rad50, mre11, hop1, rad52, dmc1(dmc1a, dmc1b), pms1, mlh1, msh2, msh6, mnd1, hop2, mlh2, 本文通过荧光原位杂交(FISH)实验和RT-PCR实验对这些基因在贾第虫双核中的存在情况、表达情况进行了实验研究。FISH实验的结果显示，这些基因在两个细胞核中都有杂交信号，表明这些基因在两个细胞核中都存在，提示贾第虫的双核中所含基因应该是相同的；RT-PCR实验结果进一步表明，这些基因在贾第虫中都是活跃转录的，提示贾第虫的两个核都应该能发生基因转换。 其次，我们对贾第虫的两个核的核型进行了分析。我们先对贾第虫(WB株)滋养体细胞进行了成功的同步化，富集得到了大量的处于分裂期的细胞，然后对这些细胞进行低渗、固定等处理，制备核型样本进行观察。通过大量的实验我们成功地获得了贾第虫的核型标本，取得很好的实验观察结果。研究结果表明，大多数细胞的细胞核中的染色体数目在8-12之间，并且同一个细胞的两个核内染色体的数目不等。这提示贾第虫的染色体数目不稳定，有一个变化范围；双核之间的核型也存在差异。结合别人在别的株上所显示的不同染色体数，表明贾第虫不同株之间的核型也有差异。这些结果可能对贾第虫的株型分化乃至物种分化、抑或它的原始性或与寄生生活的适应性的相关研究具有重要意义。 |
| 英文摘要 | Giardia lamblia is a unicellular parasitic protist that inhabits the small intestine and commonly causes diarrheal disease called giardiasis. Giardia, aside from its medical importance, has been one of the earliest-branching eukaryotes on a phylogenetic tree. The most intriguing feature of the G. lamblia trophozoites is that they have two nuclei that are morphologically identical. Although many studies have been done on the two nuclei, it is still unknown the actual number of chromosomes, and whether the genes in the two nuclei are the same. In the present work, firstly we demonstrated the equal gene contents in the two nuclei of G. lamblia. Based on the background of our studying gene conversion in Giardia, we searched the Giardia genome and did find 13 homologues of those genes involved in gene conversion: spo11、rad50、mre11、hop1、rad52、dmc1(dmc1a、dmc1b)、pms1、mlh1、 msh2、 msh6、mnd1、hop2、mlh2. Fluorescence in situ hybridization (FISH) and RT-PCR assay were designed to study whether these genes exist in both nuclei and whether they all express. FISH results showed that these genes are found in both nuclei, confirming they are both present in each nucleus and indicating the two nuclei of Giardia contain the same gene; RT-PCR results showed that all these genes are transcriptionally active, indicating that gene conversion maybe occurred in both nuclei. Secondly, we analyzed the karyotypes of Giardia nuclei. To enrich the cultured population with mitotic cells, we synchronized trophozoite cell cycle (WB strain), which was followed by hypotonic treatment and fixation. Through lots of experiments, we applied these conventional cytogenetic techniques to Giardia successfully and got good karyotyoes. The results showed that the chromosome number is in a range of 8-12, and that the two nuclei in a single cell G. lamblia (C2 strain), indicating karyotype diversity of different Giardia strains. These results maybe have great significance to study the strain differentiation of Giardia, even the species differentiation, Giardia’s primitiveness and the adaptability of parasitism.exhibited different chromosome numbers. This indicated that the chromosome number of Giardia (WB strain) isn’t stable, which was different from the karyotype of another strain of Key Words: Giardia lamblia FISH gene conversion karyotype |
| 语种 | 中文 |
| 公开日期 | 2013-04-23 |
| 内容类型 | 学位论文 |
| 源URL | [http://159.226.149.42:8088/handle/152453/7384]  |
| 专题 | 昆明动物研究所_真核细胞进化基因组 |
| 推荐引用方式 GB/T 7714 | 唐丹. 贾第虫双核所含基因是否相同的证明与核型分析[D]. 北京. 中国科学院研究生院. 2011. |
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