A new and anomalous type of meiosis in a mantid,
            Callimantis antillarum
            saussure

The general course of meiosis in the Orthoptera is remarkably constant from species to species, and even from one suborder to another. This is at any rate true of meiosis in the male sex; owing to technical difficulties, oogenesis has been studied in only a few species, but there seems no reason to believe that it is less uniform than spermatogenesis. Such deviations from normality as do occur seem to be of two main kinds. In some species the middle part of the prophase of the first meiotic division (pachytene, and sometimes diplotene as well) are replaced by a “diffuse stage” during which the chromosomes become almost impossible to fix and stain. Such a stage is apparently present in the peculiar orthopteran Schizodactylus monstrosus (McClung and Asana 1933, 1935)-In other species the chiasmata which usually occur more or less at random along the length of the meiotic chromosomes are localized in certain definite regions. Localization of chiasmata is seen in it's most extreme form in species of the genus Mecostethus (Acrididae), where only one chiasma is usually formed in each bivalent, just near the spindle attachment (White 1936).

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Kinase CDK2 in Mammalian Meiotic Prophase I: Screening for Hetero- and Homomorphic Sex Chromosomes

International Journal of Molecular Sciences ◽

10.3390/ijms22041969 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1969

Author(s):

Sergey Matveevsky ◽

Tsenka Chassovnikarova ◽

Tatiana Grishaeva ◽

Maret Atsaeva ◽

Vasilii Malygin ◽

...

Keyword(s):

Sex Chromosomes ◽

Mammalian Species ◽

Critical Role ◽

Eukaryotic Cell ◽

Repair System ◽

Prophase I ◽

Meiotic Chromosomes ◽

Y Chromosomes ◽

Dna Mismatch Repair System ◽

Male Sex

Cyclin-dependent kinases (CDKs) are crucial regulators of the eukaryotic cell cycle. The critical role of CDK2 in the progression of meiosis was demonstrated in a single mammalian species, the mouse. We used immunocytochemistry to study the localization of CDK2 during meiosis in seven rodent species that possess hetero- and homomorphic male sex chromosomes. To compare the distribution of CDK2 in XY and XX male sex chromosomes, we performed multi-round immunostaining of a number of marker proteins in meiotic chromosomes of the rat and subterranean mole voles. Antibodies to the following proteins were used: RAD51, a member of the double-stranded DNA break repair machinery; MLH1, a component of the DNA mismatch repair system; and SUN1, which is involved in the connection between the meiotic telomeres and nuclear envelope, alongside the synaptic protein SYCP3 and kinetochore marker CREST. Using an enhanced protocol, we were able to assess the distribution of as many as four separate proteins in the same meiotic cell. We showed that during prophase I, CDK2 localizes to telomeric and interstitial regions of autosomes in all species investigated (rat, vole, hamster, subterranean mole voles, and mole rats). In sex bivalents following synaptic specificity, the CDK2 signals were distributed in three different modes. In the XY bivalent in the rat and mole rat, we detected numerous CDK2 signals in asynaptic regions and a single CDK2 focus on synaptic segments, similar to the mouse sex chromosomes. In the mole voles, which have unique XX sex chromosomes in males, CDK2 signals were nevertheless distributed similarly to the rat XY sex chromosomes. In the vole, sex chromosomes did not synapse, but demonstrated CDK2 signals of varying intensity, similar to the rat X and Y chromosomes. In female mole voles, the XX bivalent had CDK2 pattern similar to autosomes of all species. In the hamster, CDK2 signals were revealed in telomeric regions in the short synaptic segment of the sex bivalent. We found that CDK2 signals colocalize with SUN1 and MLH1 signals in meiotic chromosomes in rats and mole voles, similar to the mouse. The difference in CDK2 manifestation at the prophase I sex chromosomes can be considered an example of the rapid chromosome evolution in mammals.

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MEIOSIS IN NEUROSPORA CRASSA. II. GENETIC AND CYTOLOGICAL CHARACTERIZATION OF THREE MEIOTIC MUTANTS

Genetics ◽

10.1093/genetics/96.2.379 ◽

1980 ◽

Vol 96 (2) ◽

pp. 379-398

Author(s):

A M DeLange ◽

A J F Griffiths

Keyword(s):

Meiotic Recombination ◽

Meiotic Division ◽

Spindle Pole Body ◽

Spindle Pole ◽

Primary Defect ◽

Meiotic Mutants ◽

Meiotic Chromosomes ◽

Pole Body ◽

Spindle Pole Bodies

ABSTRACT Three recessive meiotic mutants, asc(DL95), asc(DL243) and asc(DL879), were detected by the abortion of many of their ascospores and were analyzed using both cytological and genetic methods. Even though asc(DL95), asc(DL243) and the previously studied meiotic mutant, mei-1 (Smith 1975; Lu and Galeazzi 1978), complement one another in crosses, they apparently do not recombine (DeLange and Griffiths 1980). Thus, they may represent alleles of the same gene or comprise a gene cluster. Ascospore abortion in these mutants is caused by abnormal disjunction of meiotic chromosomes. In crosses homozygous for asc(DL95), asc(DL879) or mei-1, both pairing of homologs and meiotic recombination frequencies are reduced. In each case, this primary defect is followed by the formation of univalents at metaphase I and their irregular segregation. The mutant asc(DL243) has a defect in ascus formation, and later in disjunction during the second meiotic and post-meiotic divisions. The first-acting defect before or during karyogamy results in the abortion of most cells. Some cells manage to proceed past this block. During the second meiotic division, most chromosomes of the few resulting asci are attached to only one of the two spindle-pole bodies. Disjunction at the postmeiotic division is also highly irregular. This mutant appears to be defective in the attachment of one spindle-pole body to a set of chromosomes. The defect may involve either a centromere-associated product or a spindle-pole body.

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IMPROVED RESOLUTION OF THE MEIOTIC CHROMOSOMES IN BOTH SEXES OF EUXOA SPECIES AND THEIR HYBRIDS (LEPIDOPTERA: NOCTUIDAE)

Canadian Journal of Genetics and Cytology ◽

10.1139/g76-067 ◽

1976 ◽

Vol 18 (3) ◽

pp. 537-544 ◽

Cited By ~ 8

Author(s):

P. G. Fontana

Keyword(s):

Chromosome Complement ◽

Staining Technique ◽

Chiasma Formation ◽

Female Sex ◽

Meiotic Chromosomes ◽

Structural Differences ◽

Division Spindle ◽

Male Sex ◽

First Time ◽

Lepidoptera Noctuidae

An air drying and Giemsa staining technique produces consistently good quality cytological preparations when applied to different species of Euxoa (Lepidoptera: Noctuidae) and, in particular, it allows an improved resolution of the meiotic chromosomes in both sexes. All species so far investigated have a basic haploid chromosome complement of n(♀) = 31(XX); n(♂) = (XY). A single chiasma per individual bivalent is clearly visible in the male sex. Some chiasmata are formed in interstitial positions, but, by metaphase I, they have all undergone complete terminalization while the bivalents orient axially on the first division spindle. Direct evidence for lack of chiasma formation in the 31 hormorphic bivalents in the female sex is reported for the first time for species of Noctuidae. Evidence in favor of an XY system in the female sex is discussed. Preliminary studies of the meiotic divisions in hybrid material reveal the presence of cryptic structural differences between certain taxa, and will help to elucidate taxonomic problems within this complex genus.

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Monopolar spindle attachment of sister chromatids is ensured by two distinct mechanisms at the first meiotic division in fission yeast

The EMBO Journal ◽

10.1093/emboj/cdg222 ◽

2003 ◽

Vol 22 (9) ◽

pp. 2284-2296 ◽

Cited By ~ 91

Author(s):

A. Yamamoto

Keyword(s):

Fission Yeast ◽

Meiotic Division ◽

Spindle Attachment ◽

Sister Chromatids ◽

Monopolar Spindle

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Impact of cytomixis on the microspogenesis and formation of unreduced pollen grains in monocots

Faktori eksperimental'noi evolucii organizmiv ◽

10.7124/feeo.v20.728 ◽

2017 ◽

Vol 20 ◽

pp. 26-30

Author(s):

E. A. Kravets ◽

S. H. Plohovskaya ◽

I. I. Horyunova ◽

A. I. Emets ◽

Ya. B. Blume

Keyword(s):

Meiotic Division ◽

Functional Role ◽

Fluorescent Microscopy ◽

Pollen Grains ◽

Allium Fistulosum ◽

2N Pollen ◽

Significant Progress ◽

Unreduced Pollen ◽

Meiotic Chromosomes ◽

Allium Cepa L

Aim. Despite significant progress in the investigation of cytomixis its functional role and effect on the course of meiosis as well as mechanisms of 2n pollen grains formation is still not completely clear. We have studied the destination of cytomictic chromatin as well the mechanisms of unreduced microspores formation in species of monocots with spontaneous cytomixis. Methods. Light and fluorescent microscopy. Results. The cytomictic chromatin forms additional meiotic chromosomes in the recipient microsporocytes. Many of these meiotic chromosomes undergo rearrangement and fragmentation but retain their bivalent organization. Conclusions. Cytogenetic anomalies of microsporogenesis caused by activation of cytomixis in prophase may reflect meiosis stabilization mechanisms by assimilation and adaptation or diminution and reutilization of the introduced DNA. The main mechanism of polyploidization of microsporocytes and pollen grains in studied monocots is the restitution of the first meiotic division via the formation of a meta-anaphase 1 block.Keywords: cytomixis, microsporogenesis, additional (recipient) chromosomes, meta-anaphase 1 block, Lilium croceum Chaix., Allium cepa L., Allium fistulosum L.

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XX/XY-Sex Chromosomes in Gekko gecko (Sauria, Reptilia)

Amphibia-Reptilia ◽

10.1163/156853884x-005-03-14 ◽

1984 ◽

Vol 5 (3-4) ◽

pp. 339-345 ◽

Cited By ~ 7

Author(s):

Eva Solleder ◽

M. Schmid

Keyword(s):

Bone Marrow ◽

Chromosome Number ◽

Sex Chromosomes ◽

Chromosome Pair ◽

Banding Patterns ◽

Gekko Gecko ◽

Meiotic Chromosomes ◽

Chromosomal Banding ◽

Male Sex ◽

Chromosomal Sex Determination

The mitotic karyotype, chromosomal banding patterns and male meiotic chromosomes of Gekko gecko were studied in differentially stained preparations obtained from bone marrow and testes. A chromosome number of 38 was found with a heteromorphic chromosome pair in the male sex, which indicates a XX/XY-mechanism of chromosomal sex determination. The Y-chromosome was found to be larger than the X-chromosome.

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VII.—The Genetical and Mechanical Properties of the Sex Chromosomes. VIII. The Cat (Felis domestica)

Proceedings of the Royal Society of Edinburgh Section B Biology ◽

10.1017/s0080455x00011383 ◽

1941 ◽

Vol 61 (1) ◽

pp. 78-94 ◽

Cited By ~ 1

Author(s):

P. C. Koller

Keyword(s):

Mechanical Properties ◽

Sex Chromosomes ◽

Meiotic Division ◽

Cytological Study ◽

Structural Differentiation ◽

Structural Peculiarities ◽

Male Sex

A cytological study of the testes of the cat was undertaken in order to disclose the structural differentiation of the sex chromosomes. It was hoped that an analysis of these particular chromosomes in the male sex during meiotic division might reveal structural peculiarities which would throw some light upon the highly complex genetical behaviour of tortoise-shell cats.

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