M chromosome of the wild silkworm, Bombyx mandarina (n = 27), corresponds to two chromosomes in the domesticated silkworm, Bombyx mori (n = 28)

Genome ◽  
2004 ◽  
Vol 47 (1) ◽  
pp. 96-101 ◽  
Author(s):  
Yutaka Banno ◽  
Takashi Nakamura ◽  
Eiichi Nagashima ◽  
Hiroshi Fujii ◽  
Hiroshi Doira
Keyword(s):  
Chromosome Number ◽  
Bombyx Mori ◽  
Chromosome Segregation ◽  
Germ Cells ◽  
Mitotic Chromosome ◽  
Chromosome Configuration ◽  
Bombyx Mandarina ◽  
Wild Silkworm ◽  
Silkworm Bombyx Mori ◽  
Metaphase I

Chromosomes of Bombyx mori (n = 28) and of Bombyx mandarina (n = 27) were studied cytogenetically to resolve the origin of the large M chromosome in the Japaneses type of B. mandarina. In the F1 progeny from the reciprocal cross between B. mandarina and B. mori, the mitotic chromosome number was 2n = 55, and a chromosome configuration of 26 bivalents plus 1 trivalent was observed at metaphase I of germ cells. The trivalent chromosome consisted of the M chromosome from B. mandarina and two chromosomes from B. mori. When males of B. mori were mated to the F1 females, nuclei with two types of chromosome number (2n = 55 and 2n = 56) and two sets of chromosome pairs (26 bivalents plus 1 trivalent versus 28 bivalents) were observed in the metaphase I stage. Linkage analysis showed that the 14th chromosome of B. mori was involved in these two types of chromosome segregation. This result indicates that the M chromosome in B. mandarina arose from a fusion between a chromosome corresponding to the 14th linkage group and another, yet unidentified linkage group.Key words: Bombyx mandarina, Bombyx mori, chromosome dimorphism, linkage, karyotype.

scholarly journals Resistance comparison of domesticated silkworm (Bombyx mori L.) and wild silkworm (Bombyx mandarina M.) to phoxim insecticide

2010 ◽  
Vol 9 (12) ◽  
pp. 1771-1775 ◽  
Author(s):  
Li Bing ◽  
Wang Yanhong ◽  
Liu Haitao ◽  
Xu YaXiang ◽  
Wei Zhengguo ◽  
...  
Keyword(s):  
Bombyx Mori ◽  
Bombyx Mandarina ◽  
Wild Silkworm ◽  
Bombyx Mori L ◽  
Silkworm Bombyx Mori

scholarly journals Nucleotide Diversity and Selection Signature in the Domesticated Silkworm,Bombyx mori, and Wild Silkworm,Bombyx mandarina

2011 ◽  
Vol 11 (155) ◽  
pp. 1-16 ◽  
Author(s):  
Yi Guo ◽  
Yi-Hong Shen ◽  
Wei Sun ◽  
Hirohisa Kishino ◽  
Zhong-Huai Xiang ◽  
...  
Keyword(s):  
Bombyx Mori ◽  
Nucleotide Diversity ◽  
Selection Signature ◽  
Bombyx Mandarina ◽  
Wild Silkworm ◽  
Silkworm Bombyx Mori

scholarly journals Transgenic and knockout analyses of Masculinizer and doublesex illuminated the unique functions of doublesex in germ cell sexual development of the silkworm, Bombyx mori

2020 ◽  
Author(s):  
Tomohisa Yuzawa ◽  
Misato Matsuoka ◽  
Megumi Sumitani ◽  
Fugaku Aoki ◽  
Hideki Sezutsu ◽  
...  
Keyword(s):  
Germ Cell ◽  
Bombyx Mori ◽  
Germ Cells ◽  
Sexual Development ◽  
Somatic Cells ◽  
Specific Factor ◽  
Physical Interaction ◽  
Homozygous Mutation ◽  
Male Specific ◽  
Silkworm Bombyx Mori

Abstract Background: Masculinizer (Masc) plays a pivotal role in male sex determination in the silkworm, Bombyx mori. Masc is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. The male isoform of Bmdsx (BmdsxM) induces male differentiation in somatic cells, while females express the female isoform of Bmdsx (BmdsxF), which promotes female differentiation in somatic cells. Our previous findings suggest that Masc could direct the differentiation of genetically female (ZW) germ cells into sperms. However, it remains unclear whether Masc directly induces spermatogenesis of if it promotes male differentiation in germ cells indirectly by inducing the expression of BmdsxM. Results: In this study, we performed genetic analyses using a transgenic line that expressed Masc, as well as various Bmdsx knockout lines. Masc-expressing females express both BmdsxF and BmdsxM and have degenerated ovaries combined with testis-like tissues, which produce sperm. We found that Masc-expressing females with a homozygous mutation in BmdsxM showed normal development in ovaries. The formation of testis-like tissues was abolished in these females. In comparison, Masc-expressing females carrying a homozygous mutation in BmdsxF exhibited almost complete male-specific development in gonads and germ cells. These results suggest that BmdsxM can induce male development in germ cells and internal genital organs, while BmdsxF inhibits BmdsxM activity and represses male differentiation. To investigate whether MASC directly controls male-specific splicing of Bmdsx and identify RNAs that form complexes with MASC in testes, we performed RNA immunoprecipitation (RIP) using an anti-MASC antibody. We found that MASC formed a complex with AS1 lncRNA , which is a testis-specific factor involved in the male-specific splicing of Bmdsx pre-mRNA . Conclusions: Taken together, our findings suggest that Masc induces male differentiation in gonads and germ cells by enhancing the production of BmdsxM. Physical interaction between MASC and AS1 lncRNA may be important for the BmdsxM expression in the testis. Unlike Drosophila dsx, BmdsxM was able to induce spermatogenesis in genetically female (ZW) germ cells. To the best of our knowledge, this is the first report that the role of dsx in germ cell sexual development is different between insect species.

scholarly journals Condensin restructures chromosomes in preparation for meiotic divisions

2004 ◽  
Vol 167 (4) ◽  
pp. 613-625 ◽  
Author(s):  
Raymond C. Chan ◽  
Aaron F. Severson ◽  
Barbara J. Meyer
Keyword(s):  
Caenorhabditis Elegans ◽  
Chromosome Segregation ◽  
Germ Cells ◽  
Protein Complex ◽  
Mitotic Chromosome ◽  
Meiotic Chromosome ◽  
Ordered Structure ◽  
Homologous Chromosomes ◽  
Sister Chromatids ◽  
Chromosome Resolution

The production of haploid gametes from diploid germ cells requires two rounds of meiotic chromosome segregation after one round of replication. Accurate meiotic chromosome segregation involves the remodeling of each pair of homologous chromosomes around the site of crossover into a highly condensed and ordered structure. We showed that condensin, the protein complex needed for mitotic chromosome compaction, restructures chromosomes during meiosis in Caenorhabditis elegans. In particular, condensin promotes both meiotic chromosome condensation after crossover recombination and the remodeling of sister chromatids. Condensin helps resolve cohesin-independent linkages between sister chromatids and alleviates recombination-independent linkages between homologues. The safeguarding of chromosome resolution by condensin permits chromosome segregation and is crucial for the formation of discrete, individualized bivalent chromosomes.

Geographic dimorphism of the wild silkworm, Bombyx mandarina, in the chromosome number and the occurrence of a retroposon-like insertion in the arylphorin gene

Genome ◽  
1999 ◽  
Vol 42 (6) ◽  
pp. 1117-1120 ◽  
Author(s):  
T. Nakamura ◽  
Y. Banno ◽  
T. Nakada ◽  
S.K. Nho ◽  
M.K. Xü ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Bombyx Mandarina ◽  
Wild Silkworm

Geographic dimorphism of the wild silkworm, Bombyx mandarina, in the chromosome number and the occurrence of a retroposon-like insertion in the arylphorin gene

Genome ◽  
1999 ◽  
Vol 42 (6) ◽  
pp. 1117-1120 ◽  
Author(s):  
T Nakamura ◽  
Y Banno ◽  
T Nakada ◽  
S K Nho ◽  
M K Xü ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Chromosome Number ◽  
South Korea ◽  
Chain Reaction ◽  
Bombyx Mandarina ◽  
Pcr Polymerase Chain Reaction ◽  
Geographical Populations ◽  
Wild Silkworm ◽  
Polymerase Chain

Individuals of the wild silkworm, Bombyx mandarina, collected in South Korea (Taegu City) and Japan (Tsushima Islands and Fukuoka City) had the chromosome number of 2n = 54, while those collected in China (Hangzhou City) had the chromosome number of 2n = 56. Analysis by PCR (polymerase chain reaction) showed that the 66-bp-long retroposon-like insertion known in the arylphorin gene was present in the B. mandarina specimens with 2n = 54, but not in those with 2n = 56. Thus, dimorphism in the chromosome number coincided with the occurrence of the insertion. It is likely that the boundary dividing the two geographic B. mandarina populations lies somewhere in the northern part of the Korean Peninsula.Key words: Bombyx mandarina, chromosome dimorphism, arylphorin gene, geographical populations.

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