scholarly journals Role of the mod(mdg4) Common Region in Homolog Segregation in Drosophila Male Meiosis

Genetics ◽  
2007 ◽  
Vol 176 (1) ◽  
pp. 161-180 ◽  
Author(s):  
Morvarid Soltani-Bejnood ◽  
Sharon E. Thomas ◽  
Louisa Villeneuve ◽  
Kierstyn Schwartz ◽  
Chia-sin Hong ◽  
...  
Keyword(s):  
Male Meiosis ◽  
Common Region

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

Chromosoma ◽  
2001 ◽  
Vol 110 (3) ◽  
pp. 228-240 ◽  
Author(s):  
Wendy Stapleton ◽  
Suchita Das ◽  
Bruce D. McKee
Keyword(s):  
Male Meiosis

Role of microtubules and microtubule organizing centers on meiotic chromosome elimination in Sciara ocellaris

1997 ◽  
Vol 110 (6) ◽  
pp. 721-730 ◽  
Author(s):  
M.R. Esteban ◽  
M.C. Campos ◽  
A.L. Perondini ◽  
C. Goday
Keyword(s):  
Meiotic Chromosome ◽  
Chromosome Elimination ◽  
Male Meiosis ◽  
Meiotic Spindle ◽  
Monopolar Spindle ◽  
Meiotic Spindles ◽  
Cytoplasmic Microtubules ◽  
Spindle Microtubules ◽  
Meiosis I

Spindle formation and chromosome elimination during male meiosis in Sciara ocellaris (Diptera, Sciaridae) has been studied by immunofluorescence techniques. During meiosis I a monopolar spindle is formed from a single polar complex (centrosome-like structure). This single centrosomal structure persists during meiosis II and is responsible for the non-disjunction of the maternal X chromatids. During meiosis I and II non-spindle microtubules are assembled in the cytoplasmic bud regions of the spermatocytes. The chromosomes undergoing elimination during both meiotic divisions are segregated to the bud region where they associate with bundles of microtubules. The presence and distribution of centrosomal antigens in S. ocellaris meiotic spindles and bud regions has been investigated using different antibodies. gamma-Tubulin and centrin are present in the bud as well as in the single polar complex of first meiotic spindle. The results suggest that spermatocyte bud regions contain microtubule-organizing centres (MTOCs) that nucleate cytoplasmic microtubules that are involved in capturing chromosomes in the bud regions. The distribution of actin and myosin in the spermatocytes during meiosis is also reported.

scholarly journals The Drosophila Kinesin-like Protein KLP67A Is Essential for Mitotic and Male Meiotic Spindle Assembly

2004 ◽  
Vol 15 (1) ◽  
pp. 121-131 ◽  
Author(s):  
Rita Gandhi ◽  
Silvia Bonaccorsi ◽  
Diana Wentworth ◽  
Stephen Doxsey ◽  
Maurizio Gatti ◽  
...  
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Mutational Analysis ◽  
Spindle Assembly ◽  
Male Meiosis ◽  
Meiotic Spindle ◽  
Drosophila Cell ◽  
Centrosome Separation ◽  
Mutant Cells

We have performed a mutational analysis together with RNA interference to determine the role of the kinesin-like protein KLP67A in Drosophila cell division. During both mitosis and male meiosis, Klp67A mutations cause an increase in MT length and disrupt discrete aspects of spindle assembly, as well as cytokinesis. Mutant cells exhibit greatly enlarged metaphase spindle as a result of excessive MT polymerization. The analysis of both living and fixed cells also shows perturbations in centrosome separation, chromosome segregation, and central spindle assembly. These data demonstrate that the MT plus end-directed motor KLP67A is essential for spindle assembly during mitosis and male meiosis and suggest that the regulation of MT plus-end polymerization is a key determinant of spindle architecture throughout cell division.

scholarly journals New data on karyotype, spermatogenesis and ovarian trophocyte ploidy in three aquatic bug species of the families Naucoridae, Notonectidae, and Belostomatidae (Nepomorpha, Heteroptera)

2020 ◽  
Vol 14 (1) ◽  
pp. 139-156 ◽  
Author(s):  
Desislava Stoianova ◽  
Nikolay Simov ◽  
Manh Quang Vu ◽  
Duc Minh Nguyen ◽  
Snejana Grozeva
Keyword(s):  
Developmental Stages ◽  
Balkan Peninsula ◽  
Male Meiosis ◽  
Published Data ◽  
X Chromosomes ◽  
The Family ◽  
Cytogenetic Studies ◽  
High Level ◽  
Considerable Support

We report the karyotype, some aspects of spermatogenesis, and ovarian trophocytes ploidy in three aquatic bug species: Ilyocoris cimicoides (Linnaeus, 1758), Notonecta glauca Linnaeus, 1758, and Diplonychus rusticus Fabricius, 1871 from previously unexplored regions – South Europe (Bulgaria) and Southeast Asia (Vietnam). Our results add considerable support for the published karyotype data for these species. In I. cimicoides, we observed achiasmate male meiosis – the first report of achiasmy for the family Naucoridae. More comprehensive cytogenetic studies in other species of the Naucoridae are required to elucidate the role of achiasmy as a character in the systematics of the family. Our observations on the association between phases of spermatogenesis and developmental stages in I. cimicoides and N. glauca differ from the previously published data. In these species, we assume that the spermatogenesis phases are not strongly associated with certain developmental stages. For further cytogenetic studies (on the Balkan Peninsula), we recommend July as the most appropriate month for collection of I. cimicoides and N. glauca. In the ovaries of both species, we studied the level of ploidy in metaphase and interphase trophocytes. In I. cimicoides, diploid and tetraploid metaphase trophocytes were found. Heteropycnotic elements, observed in interphase trophocytes of this species, represented the X chromosomes. It allowed us to determine the trophocytes ploidy at interphase (2n was repeated up to 16 times). The situation with N. glauca was different. The metaphase trophocytes were diploid and we were not able to determine the ploidy of interphase trophocytes since such conspicuous heteropycnotic elements were not found. The scarce data available suggest a tendency for a low level of trophocyte ploidy in the basal infraorders (Nepomorpha and Gerromorpha) and for a high level in the more advanced Pentatomomorpha. Data about this character in species from other infraorders are needed to confirm that tendency.

scholarly journals The Role of Chromatid Interference in Determining Meiotic Crossover Patterns

2021 ◽  
Vol 12 ◽  
Author(s):  
Marie Sarens ◽  
Gregory P. Copenhaver ◽  
Nico De Storme
Keyword(s):  
Physical Distance ◽  
Male Meiosis ◽  
The Novel ◽  
Crop Breeding ◽  
Genome Wide ◽  
A Genome ◽  
Wide Scale ◽  
Novel Method ◽  
Mechanistic Basis

Plants, like all sexually reproducing organisms, create genetic variability by reshuffling parental alleles during meiosis. Patterns of genetic variation in the resulting gametes are determined by the independent assortment of chromosomes in meiosis I and by the number and positioning of crossover (CO) events during meiotic recombination. On the chromosome level, spatial distribution of CO events is biased by multiple regulatory mechanisms, such as CO assurance, interference and homeostasis. However, little is known about how multiple COs are distributed among the four chromatids of a bivalent. Chromatid interference (CI) has been proposed as a regulatory mechanism that biases distribution of multiple COs toward specific chromatid partners, however, its existence has not been well-studied and its putative mechanistic basis remains undescribed. Here, we introduce a novel method to quantitatively express CI, and take advantage of available tetrad-based genotyping data from Arabidopsis and maize male meiosis to quantify CI effects on a genome-wide and chromosomal scale. Overall, our analyses reveal random involvement of sister chromatids in double CO events across paired chromosomes, indicating an absence of CI. However, on a genome-wide level, CI was found to vary with physical distance between COs, albeit with different effects in Arabidopsis and maize. While effects of CI are minor in Arabidopsis and maize, the novel methodology introduced here enables quantitative interpretation of CI both on a local and genome-wide scale, and thus provides a key tool to study CI with relevance for both plant genetics and crop breeding.

scholarly journals The Inactivation of Arabidopsis UBC22 Results in Abnormal Chromosome Segregation in Female Meiosis, but Not in Male Meiosis

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2418
Author(s):  
Ling Cao ◽  
Sheng Wang ◽  
Lihua Zhao ◽  
Yuan Qin ◽  
Hong Wang ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Female Parent ◽  
Male Meiosis ◽  
Female Meiosis ◽  
Callose Deposition ◽  
Protein Ubiquitination ◽  
Mutant Female ◽  
Ubiquitin Conjugating Enzymes ◽  
Plant Meiosis

Protein ubiquitination is important for the regulation of meiosis in eukaryotes, including plants. However, little is known about the involvement of E2 ubiquitin-conjugating enzymes in plant meiosis. Arabidopsis UBC22 is a unique E2 enzyme, able to catalyze the formation of ubiquitin dimers through lysine 11 (K11). Previous work has shown that ubc22 mutants are defective in megasporogenesis, with most ovules having no or abnormally functioning megaspores; furthermore, some mutant plants show distinct phenotypes in vegetative growth. In this study, we showed that chromosome segregation and callose deposition were abnormal in mutant female meiosis while male meiosis was not affected. The meiotic recombinase DMC1, required for homologous chromosome recombination, showed a dispersed distribution in mutant female meiocytes compared to the presence of strong foci in WT female meiocytes. Based on an analysis of F1 plants produced from crosses using a mutant as the female parent, about 24% of female mutant gametes had an abnormal content of DNA, resulting in frequent aneuploids among the mutant plants. These results show that UBC22 is critical for normal chromosome segregation in female meiosis but not for male meiosis, and they provide important leads for studying the role of UBC22 and K11-linked ubiquitination.

scholarly journals A role of territory formation in disruption of heterologous pairings in Drosophila male meiosis

2020 ◽  
Author(s):  
Christopher A. Hylton ◽  
John E. Tomkiel Dean
Keyword(s):  
In Situ Hybridization ◽  
Fluorescent In Situ Hybridization ◽  
Fruit Fly ◽  
Male Meiosis ◽  
Chromosome 3 ◽  
Prophase I ◽  
Territory Formation ◽  
Nuclear Domains

Pairings between heterologous chromosomes in meiosis can lead to nondisjunction and the production of aneuploid gametes. To minimize these aberrant outcomes, organisms have evolved mechanisms to disrupt such improper pairings prior to orientation and segregation. In the male fruit fly, Drosophila melanogaster, bivalents segregate to distinct nuclear domains in prophase I, and it has been proposed that the formation of these distinct territories may play a role in disrupting interactions between limited homologies on heterologous chromosomes. To test this, we used fluorescent in situ hybridization to examine pairing between the X chromosome and Dp(1;3) chromosomes in which a segment of the X had been transposed to chromosome 3. We found that 120kb of homology was sufficient to insure nearly complete pairing but was not sufficient to direct merotelic segregation of the paired elements, suggesting that such pairings were being disrupted. We compared the perdurance of X / Dp(1;3) pairings to that of X / Dp(1;Y) pairings (in which homologs are paired),and found that heterologous pairings were disrupted at a higher frequency at the S2b stage of prophase I, the stage at which territory formation is initiated. Our results support the model that movement of bivalents into distinct domains in prophase I provides a mechanism to disrupt pairings between limited regions of homology, and thus may be one means of preventing improper segregation of heterologs in this organism.

320. THE ROLE OF FIZZY RELATED 1 IN MALE MEIOSIS

2010 ◽  
Vol 22 (9) ◽  
pp. 120
Author(s):  
L. Hopkins ◽  
V. Pye ◽  
B. Fraser ◽  
J. Holt ◽  
K. Jones ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Mammalian Cells ◽  
Binding Capacity ◽  
Cyclin B1 ◽  
Male Meiosis ◽  
Conditional Knockout ◽  
Wild Type ◽  
Cell Cycle Protein ◽  
Sperm Analysis

Accurate chromosome segregation during mitosis and meiosis is facilitated by a regulatory complex known as the Anaphase Promoting Cyclosome (APC), an ubiquitin ligase complex that tags proteins with ubiquitin. Subsequently targeted proteins are recognised by the 26S proteosome and degraded. In mammalian cells, two temporally regulated co-activators are required for the APC to function; fizzy and fzr1. In studies of female oocyte development fzr1 has been demonstrated to play an important role in maintaining G2 arrest during meiosis by controlling spatial levels of the cell cycle protein Cyclin B1 but the role of Fzr1 in spermatogenesis remains unknown. Germ cell specific conditional knockout fzr1mice were generated using the DDX4-Cre and flox/flox fzr1 mouse lines and initial gross morphological analysis indicated that at 7 weeks of age null mice possessed significantly smaller testes (21.81mg ± 0.23mg) when compared to heterozygote (99.86mg ± 1.58mg) and wildtype littermates (93.06mg ± 1.16mg) n = 3 P < 0.0001. Quantitative gene expression analysis confirmed almost complete absence of fzr1 transcript in testes (20-fold decrease) in comparison to wild-type. Immunoblotting and immunohistochemistry revealed no expression of Fzr1 protein in meiotic and post meiotic germ cells when compared to heterozygote and wild type littermates. Histomorphological analysis of testes tissue sections revealed Fzr1 null males exhibited spermatogenic arrest and a complete absence of round spermatids with concomitant apoptosis in the residual spermatocytes. Epididymal examination confirmed a complete lack of mature spermatozoa in the cauda epididymis of null males. In contrast, both wild type and heterozygote mice displayed normal spermatogenesis and epididymal sperm analysis indicated no distinguishable differences in seminal characteristics with normal motility, morphology and sperm-zona binding capacity. Based on these observations we hypothesise that Fzr1 plays a significant role in the establishment and maintenance of meiosis possibly through regulation of key cell cycle proteins.

Using Common Region in Node-Link Displays: The Role of Field Dependence/Independence

1998 ◽  
Vol 66 (3) ◽  
pp. 197-207 ◽  
Author(s):  
Todd L. Chmielewski ◽  
Donald F. Dansereau ◽  
Jeremy L. Moreland
Keyword(s):  
Field Dependence ◽  
Common Region

Cloning and expression analysis of TSK1, a wheat SKP1 homologue, and functional comparison with Arabidopsis ASK1 in male meiosis and auxin signalling

2006 ◽  
Vol 33 (4) ◽  
pp. 381 ◽  
Author(s):  
Chijun Li ◽  
Yu Liang ◽  
Changbin Chen ◽  
Junhua Li ◽  
Yunyuan Xu ◽  
...  
Keyword(s):  
In Situ Hybridisation ◽  
Male Meiosis ◽  
Cloning And Expression ◽  
35S Promoter ◽  
Gene Encoding ◽  
Functional Conservation ◽  
Auxin Signalling ◽  
Dividing Cells

Plants possess multiple homologues of the SKP1 gene encoding an essential subunit of the SCF ubiquitin ligases, but only ASK1 (Arabidopsis SKP1-like 1) and ASK2 have been characterised genetically. In addition, little is known about the function of SKP1 homologues in monocots. Here we report on a winter wheat homologue of SKP1 named TSK1 (Triticum aestivum SKP1-like 1). Expression analyses revealed that it was expressed predominantly in young roots and floral buds. RNA in situ hybridisation showed that it was expressed in the shoot apical meristem (SAM) and anthers, especially the tapetum and microsporocytes at the time of meiosis. It was also expressed in almost the entire meristematic and elongation zones of the root. These observations indicated that TSK1 might function in dividing cells. The Arabidopsis ask1-1 mutant with overexpressed TSK1 driven by the CaMV 35S promoter exhibited partial fertility, suggesting that TSK1 could partially restore function in meiosis to the ask1-1 mutant. In addition, overexpression of TSK1 in wild type Arabidopsis resulted in changes in auxin responses and auxin-related phenotypes, consistent with a role of ASK1 in Arabidopsis auxin response. These results suggest possible functional conservation between TSK1 and ASK1.

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