The Program of Sex Chromosome Pairing in Meiosis Is Highly Conserved Across Marsupial Species

An ultrastructural study was performed on the sex chromosomes (male X1X2X3O) during the spermatogenesis of Tegenaria domestica (Arachnida, Agelenidae). This study was carried out using random and serially cut sections. During pachytene and diplotene the three X chromosomes are longitudinally paired. Each of these consists of a central core of condensed chromatin, surrounded by a field of dense chromatin projections through which the chromosomes are in contact with one another. These projections may be responsible for the recognition and pairing of the sex chromosomes and in some way participate in their non-disjunction during anaphase I. A study of the structure and behaviour of the sex chromosomes during spermatogenesis is also presented. The available information on non-synaptonemal complex-mediated chromosome pairing and a systematization of sex chromosome structure in spiders are discussed.

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Sex chromosome pairing during male meiosis in marsupials

Chromosoma ◽

10.1007/bf00330728 ◽

1982 ◽

Vol 86 (1) ◽

pp. 27-47 ◽

Cited By ~ 70

Author(s):

Peter Sharp

Keyword(s):

Chromosome Pairing ◽

Sex Chromosome ◽

Male Meiosis

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Sibling species of the blackfly Prosimulium onychodactylum (Simuliidae, Diptera): a salivary gland chromosome study

Canadian Journal of Zoology ◽

10.1139/z83-369 ◽

1983 ◽

Vol 61 (12) ◽

pp. 2816-2835 ◽

Cited By ~ 10

Author(s):

Lester J. Newman

Keyword(s):

Salivary Gland ◽

Reproductive Isolation ◽

Sibling Species ◽

Chromosome Pairing ◽

Sex Chromosomes ◽

Sex Chromosome ◽

Homologous Pairing ◽

Chromosome Markers ◽

Chromosome Arm ◽

Backcross Hybrids

Larvae of the morphospecies Prosimulium onychodactylum collected from two streams in northern Oregon are divided into 11 sibling species based on fixed and polymorphic inversions. The sibling species have differentiated sex chromosomes; each sibling species falls into one of two groups based on the chromosome arm which carries the sex chromosome markers. Males exhibit lack of homologous pairing or inversion heterzygosity and females have complete chromosome pairing or inversion homozygosity. There is a succession of sibling species which mature in the streams from January through September. Mature larvae of each sibling species are present for about 6 weeks; some are synchronic while others are allochronic. Some of the sibling species occur in the same stream and others are in different streams. Sibling species which are both synchronic and sympatric appear to be reproductively isolated. Reproductive isolation may not be complete for sibling species which are normally allopatric or allochronic; small numbers of F1 and backcross hybrids were found between some of these sibling species. The division of the morphospecies into sibling species was also observed in collections from Washington through northern California.

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Pattern of X–Y chromosome pairing in the Japanese field vole, Microtus montebelli

Genome ◽

10.1139/g97-807 ◽

1997 ◽

Vol 40 (6) ◽

pp. 829-833 ◽

Cited By ~ 6

Author(s):

P. M. Borodin ◽

M. B. Rogatcheva ◽

K. Koyasu ◽

K. Fukuta ◽

K. Mekada ◽

...

Keyword(s):

Synaptonemal Complex ◽

Chromosome Pairing ◽

Sex Chromosomes ◽

Sex Chromosome ◽

Chromosomal Evolution ◽

The Other ◽

Field Vole ◽

Y Chromosomes ◽

The One ◽

Ancestral Type

Pairing of X and Y chromosomes at meiotic prophase in males of Microtus montebelli was analyzed. The sex chromosomes form a synaptonemal complex at pachytene and end-to-end association at diakinesis – metaphase I in two species of the genus Microtus (M. montebelli and M. oeconomus) only, while they do not pair at all in the other species of this genus that have been studied so far. These data confirm that M. montebelli and M. oeconomus are very closely related in their origin. It is suggested that the sex chromosomes of M. montebelli and M. oeconomus display the ancestral type of X–Y pairing. The lack of X–Y pairing in most species of Microtus appeared after the split in lineage that led to M. oeconomus and M. montebelli on the one hand and the remaining species on the other.Key words: Microtus montebelli, arvicoline phylogeny, synaptic sex chromosome, synaptonemal complex, chromosomal evolution.

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