BIOLOGICAL STUDIES ON ANCESTORAL INSECT SPECIES OF THE SILKWORM,BOMBYXMORI

四龄2 ~五龄2日龄的B. bagina 4龄幼虫的雄性性腺处于前合子期，适合于2n染色体数目的计数。5龄第4天性腺处于第一次减数分裂前期，用于单倍体染色体数目的观察。来自韩国大邱市、日本对马岛和日本福冈市的B. japonina个体的2n=54，n=27。而中国人则有2n=56，n=28。没有观察到标本之间的染色体形态特征的差异。PCR的目的是获得的产品覆盖整个内含子3和arylphorin基因的外显子4的一部分，因此可能是409 bp的大小根据数据为家蚕。在第一次PCR扩增的几条扩增带中，从凝胶中提取一条500 bp的脱辅基酶带，进行第二次PCR，并对最终产物进行克隆和测序。他们的心脏 ...更多信息 中国杭州、日本福冈、日本对马岛和韩国大邱的DNA序列分别为408、475、474和474 bp。除内含子的前半部分（314 ~ 379个残基）外，所有供试B. japonina的核苷酸序列均高度保守，而杭州、日本福冈和对马岛标本的核苷酸序列在外显子上完全相同。然而，Taequ（韩国）个体的序列在核苷酸序列中的三个位点略有改变。另一方面，内含子3具有66 bp长的逆转录酶样序列（314至379个残基），在日本福冈和对马岛的标本。在杭州的中国人中没有发现。这证实了之前比较日本B. Escherina菌株和中国菌株的报告。有趣的是，来自大邱的韩国B. pastina拥有插入序列。对arylphorin基因的聚合酶cahin反应分析表明，在染色体数目为2n=54，n=27的B.另一方面，2n=56，n=28的那些没有逆转录酶样插入。在日本对马岛、日本福冈和韩国大邱等地的B. pegiina中均检测到转座子样插入，而在中国杭州的B. pegiina中未检测到。插入的发生与本研究分析的2n=54，n=27染色体构型一致。前人的核仁组织者杂交分析表明，家蚕B. mori的日本群体与中国群体存在差异，而中国群体与B. mori的亲缘关系较近。目前的分析支持了来自韩国的B. peculina类似于来自日本的推断。少

The gonads of males B.mandarina larvae from day 2 of the fourth instar to day 2 of the fifth instar were found to be at the premiotic stage and suitable for the counting of 2n chromosome number. On day 4 of the fifth instar the gonads were at the first meiotic prophase stage and used for the observation of haploid chromosome number. The B.mandarina individuals from Taegu City of Korea, Tsushima Island of Japan and Fukuoka City of Japan had 2n=54, n=27. On the other hand, individuals from China possessed 2n=56, n=28. No differences were observed in morphological features of the chromosomes among the specimens.PCR was designed to obtain the products covering the entire intron 3 and a part of exon 4 of the arylphorin gene and thus may be 409 bp in size according to the data for B.mori. Among several amplified bands obtained in the first PCR,a band of aporoximately 500 bp was extracted from the gel and subjected to the second PCR.The final products were cloned and sequenced. Their lengthes … More were 408,475,474 and 474 bp for the Hangzhou (China), Fukuoka (Japan), Tsushima Island (Japan) and Taegu (Korea) specimens, respectively. In all B.mandarina individuals tested, the nucleotide sequence were highly conserved except for the the former half of intron (corresponded to 314 to 379 residues) and completely the same in the of specimen from Hangzhou (China), Fukuoka (Japan) and Tsushima Island (Japan) as to the exon arts. The sequence for the Taequ (Korea) individuals, however, was slightly altered at three sites in the nucleotide sequence. On the other hand intron 3 had the 66 bp-long retroposon-like sequence (314 to 379 residues) in the Japanese specimens from Fukuoka and Tsushima Island. It was not found in the Chinese individuals from Hangzhou. These were the confirmation of a previous report comparing a Japanese B.mandarina strain and a Chinese one. Interestingly, the Korean B.mandarina from Taegu possessed the insertion sequence. Polymerase cahin reaction analysis of the arylphorin gene showed that there is a 66 bp-long retroposon-like insertion in the B.mandarina specimens which had the chromosome number of 2n=54, n=27. On the other hand, the ones with 2n=56, n=28 did not have the retroposon-like insertion. In other words, the occurrence of the insertion coincided with the 2n=54, n=27 chromosome number.A transposon-like insertion of a gene was recognized in B.mandarina speciments from Tsushima Island (Japan), Fukuoka (Japan) and Taegu (Korea) but not in those from Hangzhou (China). The occurrence of the insertion consistently coincided with the 2n=54, n=27 chromosome configuration as far as analyzed in the present study. Previous hybridization analysis of nucleolus organizer indicated that the Japanese population of B.mandarina was defferent from the Chinese population and that B.mori had closer relationship to the Chinese than to the Japanese B.mandarina. The current analysis supported the inference that B.mandarina from Korea resembles that from Japan. Less