GERM LINE-RESTRICTED, HIGHLY REPEATED DNA-SEQUENCES AND THEIR CHROMOSOMAL LOCALIZATION IN A JAPANESE HAGFISH (EPTATRETUS-OKINOSEANUS)
GERM LINE-RESTRICTED, HIGHLY REPEATED DNA-SEQUENCES AND THEIR CHROMOSOMAL LOCALIZATION IN A JAPANESE HAGFISH (EPTATRETUS-OKINOSEANUS)
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DOI：
10.1007/bf00387731
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发表时间：
1993-02-01
期刊：
影响因子：
1.6
通讯作者：
KOHNO, S
中科院分区：
文献类型：
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作者：
KUBOTA, S;KUROO, M;KOHNO, S
据了解，在胚胎发育的早期阶段，不同种类的日本鳗鱼，即A型和B型的环斑鳗、布氏环斑鳗和粘液鳗，都会消除一部分染色体。从这些鳗鱼的种系细胞和体细胞中提取高相对分子质量的DNA，并用不同的限制性内切酶进行酶切。用琼脂糖凝胶电泳法分离DNA片段。经BamHI和DRAI双酶切后，分别扩增出两条弱带和一条弱带，分别长约90、180和90个碱基，且仅限于两种类型松材线虫的种系DNA。DNA过滤杂交实验表明，这两个BamHI片段和一个DRAI片段几乎全部存在于松材线虫种质系DNA中。因此，这些DNA片段似乎在胚胎发育过程中被消除了。此外，还获得了这些片段高度重复和重复的证据。分子克隆和序列分析表明，BamHI片段主要由一组长度为95bp的紧密相关序列组成(EEEo1，代表E.okinoseanus 1的消除元件)，而DRAI片段主要由另一组长度为85bp的紧密相关序列组成(EEEo2)。这两个DNA家族约占A型松材线虫总消除DNA的19%，荧光原位杂交实验表明，这两个DNA家族位于两种类型松材线虫的几条C带阳性的小染色体上，这些小染色体仅限于生殖细胞。
The various species of Japanese hagfish, namely, Eptatretus okinoseanus (types A and B), Eptatretus burgeri and Myxine garmani, are known to eliminate a fraction of their chromosomes during early embryogenesis. High molecular weight DNA from germ line cells and somatic cells of these hagfish species was isolated and digested with different restriction enzymes. The DNA fragments were separated by agarose gel electrophoresis. Digestion with BamHI and DraI generated two weak bands and one weak band, respectively, that were estimated to be about 90, and 180 bp and about 90 bp long and were limited to the germ line DNA in both types of E. okinoseanus. DNA filter hybridization experiments showed that the two BamHI fragments and the one DraI fragment were present almost exclusively in the germ line DNA of E. okinoseanus. Thus, these DNA fragments appear to be eliminated during embryogenesis. Moreover, evidence was obtained that these fragments are highly and tandemly repeated. Molecular cloning and sequence analysis revealed that the BamHI fragments are mainly composed of a family of closely related sequences that are 95 bp long (EEEo1, for Eliminated Element of E. okinoseanus 1), and the DraI fragment is composed of another family of closely related sequences that are 85 bp long (EEEo2). The two DNA families account for about 19% of the total eliminated DNA in E. okinoseanus type A. Fluorescence in situ hybridization experiments demonstrated that the two families of DNA are located on several C-band-positive, small chromosomes that are limited to germ cells in both types of E. okinoseanus.