YTHDC2 is essential for pachytene progression and prevents aberrant microtubule-driven telomere clustering in male meiosis

AbstractGenetic background effects on the frequency of meiotic recombination have long been suspected in mice but never demonstrated in a systematic manner, especially in inbred strains. We used a recently described immunostaining technique to assess meiotic exchange patterns in male mice. We found that among four different inbred strains—CAST/Ei, A/J, C57BL/6, and SPRET/Ei—the mean number of meiotic exchanges per cell and, thus, the recombination rates in these genetic backgrounds were significantly different. These frequencies ranged from a low of 21.5 exchanges in CAST/Ei to a high of 24.9 in SPRET/Ei. We also found that, as expected, these crossover events were nonrandomly distributed and displayed positive interference. However, we found no evidence for significant differences in the patterns of crossover positioning between strains with different exchange frequencies. From our observations of >10,000 autosomal synaptonemal complexes, we conclude that achiasmate bivalents arise in the male mouse at a frequency of 0.1%. Thus, special mechanisms that segregate achiasmate chromosomes are unlikely to be an important component of mammalian male meiosis.

Download Full-text

Secondary Tetrasomic Segregation of MDH-B and Preferential Pairing of Homeologues in Rainbow Trout

Genetics ◽

10.1093/genetics/145.4.1083 ◽

1997 ◽

Vol 145 (4) ◽

pp. 1083-1092 ◽

Cited By ~ 3

Author(s):

Fred W Allendorf ◽

Roy G Danzmann

Keyword(s):

Allelic Variation ◽

Male Meiosis ◽

Proximal Region ◽

Stage Model ◽

Preferential Pairing ◽

Homologous Chromosomes ◽

Tetrasomic Inheritance ◽

Segregation Ratios ◽

Homeologous Chromosomes ◽

Duplicated Loci

We examined the inheritance of allelic variation at an isozyme locus, MDH-B, duplicated by ancestral polyploidy in salmonid fishes. We detected only disomic segregation in females. Segregation ratios in males were best explained by a mixture of disomic and tetrasomic inheritance. We propose a two-stage model of pairing in male meiosis in which, first, homologous chromosomes pair and recombine in the proximal region of the chromosome. Next, homeologous chromosomes pair and recombine distally. We suggest that this type of tetrasomic inheritance in which centromeres segregate disomically should be referred to as “secondary tetrasomy” to distinguish it from tetrasomy involving entire chromosomes (i.e., “primary tetrasomy”). Differences in segregation ratios between males indicate differences between individuals in the amount of recombination between homeologous chromosomes. We also consider the implication of these results for estimation of allele frequencies at duplicated loci in salmonid populations.

Download Full-text

Male meiosis and pollen morphology in diploid Indonesian wild bananas and cultivars

The Nucleus ◽

10.1007/s13237-021-00350-7 ◽

2021 ◽

Author(s):

Fajarudin Ahmad ◽

Yuyu S. Poerba ◽

Gert H. J. Kema ◽

Hans de Jong

Keyword(s):

Hybrid Sterility ◽

Pollen Grains ◽

Chromosome Analysis ◽

Male Meiosis ◽

Enzyme Treatment ◽

Unreduced Gamete ◽

Ploidy Levels ◽

Scientific Disciplines ◽

Sterile Pollen ◽

Mother Cells

AbstractBreeding of banana is hampered by its genetic complexity, structural chromosome rearrangements and different ploidy levels. Various scientific disciplines, including cytogenetics, linkage mapping, and bioinformatics, are helpful tools in characterising cultivars and wild relatives used in crossing programs. Chromosome analysis still plays a pivotal role in studying hybrid sterility and structural and numerical variants. In this study, we describe the optimisation of the chromosome spreading protocol of pollen mother cells focusing on the effects of standard fixation methods, duration of the pectolytic enzyme treatment and advantages of fluorescence microscopy of DAPI stained cell spreads. We demonstrate the benefits of this protocol on meiotic features of five wild diploid Musa acuminata bananas and a diploid (AA) cultivar banana “Rejang”, with particular attention on pairing configurations and chromosome transmission that may be indicative for translocations and inversions. Pollen slides demonstrate regular-shaped spores except “Rejang”, which shows fertile pollen grains of different size and sterile pollen grains, suggesting partial sterility and unreduced gamete formation that likely resulted from restitutional meiotic divisions.

Download Full-text

A role of the Drosophila homeless gene in repression of Stellate in male meiosis

Chromosoma ◽

10.1007/s004120100136 ◽

2001 ◽

Vol 110 (3) ◽

pp. 228-240 ◽

Cited By ~ 41

Author(s):

Wendy Stapleton ◽

Suchita Das ◽

Bruce D. McKee

Keyword(s):

Male Meiosis

Download Full-text

Fine structure of the kinetochores in six species of the Coleoptera

Genome ◽

10.1139/g97-051 ◽

1997 ◽

Vol 40 (3) ◽

pp. 379-385

Author(s):

Klaus Werner Wolf

Keyword(s):

Direct Contact ◽

Karyotype Evolution ◽

Coccinella Septempunctata ◽

Cell Types ◽

Male Meiosis ◽

Serial Sections ◽

Cell Type ◽

Present Survey ◽

Transmission Electron ◽

Size Variability

Kinetochore structure was examined in a total of 6 species from 5 different families of the Coleoptera using transmission electron microscopy of ultrathin serial sections. Metaphase spermatogonia and primary and secondary spermatocytes were studied in Tenebrio molitor (Tenebrionidae) to determine whether kinetochore structure varies depending on the cell type. In all three cell types, the kinetochore microtubules (MTs) were in direct contact with the chromosomal surface, and kinetochore plates were not detectable. In the other species, only metaphase I spermatocytes were examined. As in T. molitor, distinct kinetochore plates were also absent in Adelocera murina (Elateridae), Agapanthia villosoviridescens (Cerambycidae), and Coccinella septempunctata (Coccinellidae). However, bivalents in male meiosis of two representatives of the Chrysomelidae, Agelastica alni and Chrysolina graminis, showed roughly spherical kinetochores at their poleward surfaces. Microtubules were in contact with this material. Thus, although the present survey covers only a small number of species, it is clear that at least two kinetochore types occur in the Coleoptera. The cytological findings are discussed in the context of chromosome number and genome size variability in the Coleopteran families studied. It is suggested that properties of the kinetochores could play a role in karyotype evolution in the Coleoptera.Key words: bivalent, microtubule, meiosis, metaphase, spermatocyte.

Download Full-text

TETRASPORE is required for male meiotic cytokinesis in Arabidopsis thaliana

Development ◽

10.1242/dev.124.13.2645 ◽

1997 ◽

Vol 124 (13) ◽

pp. 2645-2657 ◽

Cited By ~ 5

Author(s):

M. Spielman ◽

D. Preuss ◽

F.L. Li ◽

W.E. Browne ◽

R.J. Scott ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Pollen Development ◽

Male Meiosis ◽

Pollen Grain ◽

Flowering Plants ◽

External Wall ◽

Normal Pollen ◽

Wide Range ◽

Asymmetric Divisions ◽

And Function

In flowering plants, male meiosis occurs in the microsporocyte to produce four microspores, each of which develops into a pollen grain. Here we describe four mutant alleles of TETRASPORE (TES), a gene essential for microsporocyte cytokinesis in Arabidopsis thaliana. Following failure of male meiotic cytokinesis in tes mutants, all four microspore nuclei remain within the same cytoplasm, with some completing their developmental programmes to form functional pollen nuclei. Both of the mitotic divisions seen in normal pollen development take place in tes mutants, including the asymmetric division required for the differentiation of gametes; some tes grains perform multiple asymmetric divisions in the same cytoplasm. tes pollen shows a variety of abnormalities subsequent to the cytokinetic defect, including fusion of nuclei, formation of ectopic internal walls, and disruptions to external wall patterning. In addition, ovules fertilized by tes pollen often abort, possibly because of excess paternal genomes in the endosperm. Thus tes mutants not only reveal a gene specific to male meiosis, but aid investigation of a wide range of processes in pollen development and function.

Download Full-text

Unorthodox male meiosis in Trichosia pubescens (Sciaridae). Chromosome elimination involves polar organelle degeneration and monocentric spindles in first and second division

Journal of Cell Science ◽

10.1242/jcs.107.1.299 ◽

1994 ◽

Vol 107 (1) ◽

pp. 299-312 ◽

Cited By ~ 3

Author(s):

H. Fuge

Keyword(s):

Meiotic Division ◽

Metaphase Plate ◽

Chromosome Elimination ◽

Spindle Pole ◽

Male Meiosis ◽

Early Prophase ◽

Late Prophase ◽

Section Electron ◽

The One ◽

Polar Organelle

Male meiosis in Trichosia pubescens (Sciaridae) was investigated by means of serial section electron microscopy and immunofluorescence light microscopy. From earlier studies of another sciarid fly, Sciara coprophila (Phillips (1967) J. Cell. Biol. 33, 73–92), it is known that the spindle poles in sciarid spermatogonia are characterized by pairs of ‘giant centrioles’, ring-shaped organelles composed of large numbers of singlet microtubules. In the present study spermatocytes in early prophase of Trichosia were found to possess single giant centrioles at opposite sides of the nucleus. The obvious reduction in centriole number from the spermatogonial to the spermatocyte stage is suggested to be the result of a suppression of daughter centriole formation. In late prophase, a large aster is developed around the centriole at one pole. At the opposite pole no comparable aster is formed. Instead, a number of irregular centriolar components appear in this region, a process that is understood to be a degeneration of the polar organelle. The components of the degenerate pole migrate into a cytoplasmic protrusion (‘bud’), which later is also utilized for the elimination of paternal chromosomes. The existence of only one functional polar centre is the reason for the formation of a monopolar monocentric spindle in first meiotic division, which in turn is one of the prerequisites for the elimination of paternal chromosomes. While the set of maternal and L chromosomes orientates and probably moves towards the pole, paternal chromosomes seem to be unable to contact the pole, possibly due to an inactivation of their kinetochores. Retrograde (‘away from the pole’) chromosome motion not involving kinetochores is assumed. Eventually, paternal chromosomes move into the pole-distal bud and are eliminated by casting off, together with the components of the degenerate polar organelle. Chromosome elimination can be delayed until the second meiotic division. The spindle of the second meiotic division is bipolar and monocentric. One spindle pole is marked by the polar centre of first division. The opposite spindle apex is devoid of a polar centre. It is assumed that spindle bipolarity in the second division is induced by the amphi-orientated chromosomes themselves. The maternal and L chromosome set (except the non-disjunctional X chromosome, which is found near the polar centre) congress in a metaphase plate, divide and segregate. Of the two daughter nuclei resulting from the second meiotic division, the one containing the X chromatids is retained as the nucleus of the future spermatozoon. The other nucleus becomes again eliminated within a second cytoplasmic bud.

Download Full-text

Karyotype, sex determination and male meiosis in three benthic water bugs (Hemiptera: Nepomorpha: Aphelocheiridae)

Aquatic Insects ◽

10.1080/01650424.2017.1346260 ◽

2017 ◽

Vol 38 (3) ◽

pp. 115-124 ◽

Cited By ~ 2

Author(s):

Desislava Stoianova ◽

S. Grozeva ◽

N. Simov ◽

V. Kuznetsova

Keyword(s):

Sex Determination ◽

Male Meiosis ◽

Water Bugs

Download Full-text

Distinct prophase arrest mechanisms in human male meiosis

10.1101/195321 ◽

2017 ◽

Author(s):

Sabrina Z. Jan ◽

Aldo Jongejan ◽

Cindy M. Korver ◽

Saskia K. M. van Daalen ◽

Ans M. M. van Pelt ◽

...

Keyword(s):

Genomic Stability ◽

Male Meiosis ◽

Type I ◽

Type Ii ◽

Meiotic Arrest ◽

Homologous Chromosomes ◽

Xy Body ◽

Chromosome Synapsis ◽

Human Male ◽

Meiotic Crossover

To prevent chromosomal aberrations to be transmitted to the offspring, strict meiotic checkpoints are in place to remove aberrant spermatocytes. However, in about 1% of all males these checkpoints cause complete meiotic arrest leading to azoospermia and subsequent infertility. We here unravel two clearly distinct meiotic arrest mechanisms that act during the prophase of human male meiosis. Type I arrested spermatocytes display severe asynapsis of the homologous chromosomes, disturbed XY-body formation and increased expression of the Y-chromosome encoded gene ZFY and seem to activate a DNA damage pathway leading to induction of p63 mediated spermatocyte elimination. Type II arrested spermatocytes display normal chromosome synapsis, normal XY-body morphology and meiotic crossover formation but have a lowered expression of several cell cycle regulating genes and fail to properly silence the X-chromosome encoded gene ZFX. Discovery and understanding of these meiotic arrest mechanisms increases our knowledge on how genomic stability is guarded during human germ cell development.

Download Full-text

polo, a mitotic mutant of Drosophila displaying abnormal spindle poles

Journal of Cell Science ◽

10.1242/jcs.89.1.25 ◽

1988 ◽

Vol 89 (1) ◽

pp. 25-38 ◽

Cited By ~ 5

Author(s):

C.E. Sunkel ◽

D.M. Glover

Keyword(s):

High Frequency ◽

Sex Chromosome ◽

Living Cells ◽

Male Meiosis ◽

Mitotic Spindles ◽

Spindle Poles ◽

Immunofluorescence Studies ◽

Meiotic Spindles ◽

Circular Arrangement ◽

Chromosome Disjunction

Neuroblast cells in larvae homozygous for mutant alleles of the locus polo show a high frequency of metaphases in which the chromosomes have a circular arrangement, and anaphase figures in which chromosomes appear to be randomly oriented with respect to at least one of the spindle poles. These defects appear to lead to the production of polyploid cells. Sex chromosome disjunction is affected in male meiosis, primarily in the second division, and the meiotic spindles of living cells are abnormal. One allele is a larval lethal, whereas another is semi-lethal with about 7% of homozygotes surviving as adults. Embryos from homozygous polo females have aberrant mitotic spindles that are highly branched and have broad poles. Immunofluorescence studies with an antibody that recognizes an antigen associated with the centrosome indicate that the organization of this organelle is disrupted in the mutant embryos.

Download Full-text