Cytological evidence for holocentric chromosomes of the silkworms, Bombyx mori and B. mandarina, (Bombycidae, Lepidoptera)

Murakami, Akio; Imai, Hirotami T.

doi:10.1007/bf00331804

Cited by 130 publications

(85 citation statements)

References 30 publications

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“…Compared to B. mori, markers for the genes tpi and apterous were shared on the Z chromosome of the postman butterfly H. melpomene (Yasukochi et al 2006) and inversions have been demonstrated in the squinting bush brown butterfly Bicyclus anynana (Beldade et al 2009). Compared to the B. mori chromosome 1 (Z), the B. anynana inversions took place in regions syntenic to positions 1-10.88 Mb, but as Lepidoptera have holocentric chromosomes that do not exhibit primary constrictions indicative of centromeres (Murakami and Imai 1974), we cannot assign such rearrangements to chromosome ''arms'' (Wolf 1996). The tobacco hornworm moth Manduca sexta was found to have an inversion (relative to B. mori) encompassing nearly half of the Z chromosome (Yasukochi et al 2009), and studies by Beldade et al (2009) and Yasukochi et al (2009) confirm that rearrangements have affected the structures of the Z chromosome among lepidopteran lineages.…”

Section: Discussionmentioning

confidence: 99%

A rearrangement of the Z chromosome topology influences the sex-linked gene display in the European corn borer, Ostrinia nubilalis

et al. 2011

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Males are homogametic (ZZ) and females are heterogametic (WZ) with respect to the sex chromosomes in many species of butterflies and moths (insect order Lepidoptera). Genes on the Z chromosome influence traits involved in larval development, environmental adaptation, and reproductive isolation. To facilitate the investigation of these traits across Lepidoptera, we developed 43 degenerate primer pairs to PCR amplify orthologs of 43 Bombyx mori Z chromosome-linked genes. Of the 34 orthologs that amplified by PCR in Ostrinia nubilalis, 6 co-segregated with the Z chromosome anchor markers kettin (ket) and lactate dehydrogenase (ldh), and produced a consensus genetic linkage map of ~89 cM in combination with 5 AFLP markers. The O. nubilalis and B. mori Z chromosomes are comparatively co-linear, although potential gene inversions alter terminal gene orders and a translocation event disrupted synteny at one chromosome end. Compared to B. mori orthologs, O. nubilalis Z chromosome-linked genes showed conservation of tissuespecific and growth-stage-specific expression, although some genes exhibited species-specific expression across developmental stages or tissues. The O. nubilalis Z chromosome linkage map provides new tools for isolating quantitative trait loci (QTL) involved in sex-linked traits that drive speciation and it exposes genome rearrangements as a possible mechanism for differential gene regulation in Lepidoptera. Abstract Males are homogametic (ZZ) and females are heterogametic (WZ) with respect to the sex chromosomes in many species of butterflies and moths (insect order Lepidoptera). Genes on the Z chromosome influence traits involved in larval development, environmental adaptation, and reproductive isolation. To facilitate the investigation of these traits across Lepidoptera, we developed 43 degenerate primer pairs to PCR amplify orthologs of 43 Bombyx mori Z chromosomelinked genes. Of the 34 orthologs that amplified by PCR in Ostrinia nubilalis, 6 co-segregated with the Z chromosome anchor markers kettin (ket) and lactate dehydrogenase (ldh), and produced a consensus genetic linkage map of *89 cM in combination with 5 AFLP markers. The O. nubilalis and B. mori Z chromosomes are comparatively co-linear, although potential gene inversions alter terminal gene orders and a translocation event disrupted synteny at one chromosome end. Compared to B. mori orthologs, O. nubilalis Z chromosomelinked genes showed conservation of tissue-specific and growth-stage-specific expression, although some genes exhibited species-specific expression across developmental stages or tissues. The O. nubilalis Z chromosome linkage map provides new tools for isolating quantitative trait loci (QTL) involved in sex-linked traits that drive speciation and it exposes genome rearrangements as a possible mechanism for differential gene regulation in Lepidoptera.

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Section: Discussionmentioning

confidence: 99%

A rearrangement of the Z chromosome topology influences the sex-linked gene display in the European corn borer, Ostrinia nubilalis

et al. 2011

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“…The sex chromosomes stand out in female pachytene spreads by their heterochromatic appearance and produce hemizygous inheritance patterns. In contrast, lepidopteran autosomes are far less distinct because they are cytogenetically uniform as a result of their holokinetic arrangement (that is, lacking a primary constriction, the centromere; Murakami and Imai, 1974;Carpenter et al, 2005), large number, small size and insusceptibility to banding techniques. The gene composition of the Z chromosome is conserved in Lepidoptera, although not as strongly as some of the autosomes (Beldade et al, 2009;Baxter et al, 2011;Kroemer et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Linkage map of the peppered moth, Biston betularia (Lepidoptera, Geometridae): a model of industrial melanism

et al. 2012

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We have constructed a linkage map for the peppered moth (Biston betularia), the classical ecological genetics model of industrial melanism, aimed both at localizing the network of loci controlling melanism and making inferences about chromosome dynamics. The linkage map, which is based primarily on amplified fragment length polymorphisms (AFLPs) and genes, consists of 31 linkage groups (LGs; consistent with the karyotype). Comparison with the evolutionarily distant Bombyx mori suggests that the gene content of chromosomes is highly conserved. Gene order is conserved on the autosomes, but noticeably less so on the Z chromosome, as confirmed by physical mapping using bacterial artificial chromosome fluorescence in situ hybridization (BAC-FISH). Synteny mapping identified three pairs of B. betularia LGs (11/29, 23/30 and 24/31) as being orthologous to three B. mori chromosomes (11, 23 and 24, respectively). A similar finding in an outgroup moth (Plutella xylostella) indicates that the B. mori karyotype (n ¼ 28) is a phylogenetically derived state resulting from three chromosome fusions. As with other Lepidoptera, the B. betularia W chromosome consists largely of repetitive sequence, but exceptionally we found a W homolog of a Z-linked gene (laminin A), possibly resulting from ectopic recombination between the sex chromosomes. The B. betularia linkage map, featuring the network of known melanization genes, serves as a resource for melanism research in Lepidoptera. Moreover, its close resemblance to the ancestral lepidopteran karyotype (n ¼ 31) makes it a useful reference point for reconstructing chromosome dynamic events and ancestral genome architectures. Our study highlights the unusual evolutionary stability of lepidopteran autosomes; in contrast, higher rates of intrachromosomal rearrangements support a special role of the Z chromosome in adaptive evolution and speciation.

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“…In holocentric chromosomes, the attachment region of spindle is spread throughout the chromosome. Holokinetic chromosomal organization in Lepidoptera was deduced from the missing primary constrictions and a parallel separation in mitotic anaphase (Murakami and Imai, 1974), viability of chromosome fragments (Maeki 1981), high rate of viability of X-ray induced translocations (Bauer, 1967), high doses of X-ray necessary to induce sterility and chromosome fragmentation and fusion in evolution giving rise to highly different chromosome numbers in related species. (Suomalainen,1953).…”

Section: Disscussion:-mentioning

confidence: 99%

“…As in most Lepidoptera, the chromosomes of Bombyx mori L. are holocentric (Murakami and Imai, 1974) i.e. they possess centromeres throughout the chromosome body.…”

Section: …………………………………………………………………………………………………… Introduction:-mentioning

confidence: 99%

Chromosomal Analysis of Mulberry Silkworm (Bombyx Mori. L) From Jammu Region.

Kumari¹,

Tripathi²,

Jangral³

et al. 2017

IJAR

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In the present study, the chromosomal analysis of mulberry silkworm, Bombyx mori L. was carried out in order to study its chromosome behaviour and karyotype from larval gonadal tissue. The observed diploid number was 2n=56. The mean total length, RL% and TCL% were measured at metaphase stage of gametogenesis. The chromosomal behaviour during meiotic stages viz., leptotene, zygotene, pachytene, diplotene, diakinesis and anaphase were also analyzed. Results indicate that the samples studied were males with a diploid chromosome number of 2n=56. …………………………………………………………………………………………………….... Introduction:-The order Lepidoptera includes moths and butterflies. It is a species rich order and among this order are some commercially important insects like silkmoths and many serious agricultural pests too.The mulberry silkworm is a commercially important insect which is completely domesticated and one of the most genetically studied insect and well known as lepidopteran model insect (Nagaraju and Goldsmith, 2002) apart from its importance as a producer of silk-"the queen of textiles".As in most Lepidoptera, the chromosomes of Bombyx mori L. are holocentric (Murakami and Imai, 1974) i.e. they possess centromeres throughout the chromosome body. These chromosomes are highly condensed and appear dotshaped at mitotic and meiotic metaphase stages. Their diffused centromeres and lack of special features make them difficult to identify individually. The chromosome number is known with n=28 (Kawaguchi,1928) and 2n=56 (Kawamura 1979, Yoshido et al 2005. In the present investigation, an attempt has been made to prepare a karyotype of Bombyx mori L. on the basis of decreasing chromosome length from meiotic metaphase complement. The chromosome behavior during the meiotic stages was also studied from the larval gonadal cells. Material and Methods:-Rearing of silkworm larvae:-The IIIrd instar larvae of mulberry silkworm, B.mori L. were collected from RSRS Miransahib, Jammu and transported to Cytogenetics Lab., Dept. of Zoology., University of Jammu. About 20 larvae were reared in rearing cage for further development ( fig. 1). The temperature and relative humidity was maintained as 26˚C and 80% RH for the IIIrd instar, 24-25˚C and 75% RH for IV instar and 23-24˚C temperature and around 70% RH for the V instar, the larvae were fed with mulberry leaves during larval period.

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Cytological evidence for holocentric chromosomes of the silkworms, Bombyx mori and B. mandarina, (Bombycidae, Lepidoptera)

Cited by 130 publications

References 30 publications

A rearrangement of the Z chromosome topology influences the sex-linked gene display in the European corn borer, Ostrinia nubilalis

A rearrangement of the Z chromosome topology influences the sex-linked gene display in the European corn borer, Ostrinia nubilalis

Linkage map of the peppered moth, Biston betularia (Lepidoptera, Geometridae): a model of industrial melanism

Chromosomal Analysis of Mulberry Silkworm (Bombyx Mori. L) From Jammu Region.

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