The p27cip/kip ortholog dacapo maintains the Drosophila oocyte in prophase of meiosis I

ABSTRACTIn prophase of meiosis I, homologous partner chromosomes pair and become connected by crossovers. Chiasmata, the connections formed between the partners enable the chromosome pair, called a bivalent, to attach as a single unit to the spindle. When the meiosis I spindle forms in prometaphase, most bivalents are associated with a single spindle pole and go through a series of oscillations on the spindle, attaching to and detaching from microtubules until the partners of the bivalent are bi-oriented, that is, attached to microtubules from opposite sides of the spindle, and prepared to be segregated at anaphase I. The conserved, kinetochore-associated kinase, Mps1, is essential for the bivalents to be pulled by microtubules across the spindle in prometaphase. Here we show that MPS1 is not required for kinetochores to attach microtubules but instead is necessary to trigger the migration of microtubule-attached kinetochores towards the poles. Our data support the model that Mps1 triggers depolymerization of microtubule ends once they attach to kinetochores in prometaphase. Thus, Mps1 acts at the kinetochore to co-ordinate the successful attachment of a microtubule and the triggering of microtubule depolymerization to move the chromosome.

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The external mechanics of the chromosomes III-Meiosis in triploids

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1936.0066 ◽

1936 ◽

Vol 121 (823) ◽

pp. 290-300 ◽

Cited By ~ 2

Keyword(s):

Sexual Reproduction ◽

Chromosome Pairing ◽

Natural Experiment ◽

Diploid Species ◽

Homologous Chromosomes ◽

Normal Series ◽

Mitosis And Meiosis ◽

Meiosis I ◽

Prophase Of Meiosis ◽

The Way

Triploid organisms have three homologous chromosomes of each kind instead of the two of diploids. The regular mechanism of heredity fails in these circumstances. The triploid is incapable of breeding true by sexual reproduction. But the way in which it carries out the process of chromosome pairing and segregation is of great significance. The processes take place in normal series, but the relationships they establish are abnormal. A triploid thus provides a natural experiment, with the diploid of its own species as a control for one variable, and with triploids of different species as controls for others. In Tulipa and Hyacinthus I have made use of this experiment for inducing the principles of the external mechanics of chromosomes during the prophase of meiosis. I have inferred from them the relationships between the forces working in mitosis and meiosis. The triploid forms of various Fritillaria species make it possible to test the principles of metaphase mechanics induced from observations on structural hybrids and other polyploids (Darlington, 1932, b , and 1933, c ) as well as from the exceptional behaviour in the diploid species of Fritillaria already discussed.

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The essential roles of Mps1 in spermatogenesis and fertility in mice

Cell Death and Disease ◽

10.1038/s41419-021-03815-4 ◽

2021 ◽

Vol 12 (6) ◽

Author(s):

Qiang Fang ◽

Xue-Lin Chen ◽

Lei Zhang ◽

Ya-Bin Li ◽

Tian-Zeng Sun ◽

...

Keyword(s):

Critical Role ◽

Cell Loss ◽

Conditional Knockout ◽

Male Mice ◽

Fertility Reduction ◽

Monopolar Spindle ◽

Apoptotic Genes ◽

Mitosis And Meiosis ◽

Meiosis I ◽

Prophase Of Meiosis

AbstractMonopolar spindle 1 (MPS1), which plays a critical role in somatic mitosis, has also been revealed to be essential for meiosis I in oocytes. Spermatogenesis is an important process involving successive mitosis and meiosis, but the function of MPS1 in spermatogenesis remains unclear. Here, we generated Mps1 conditional knockout mice and found that Ddx4-cre-driven loss of Mps1 in male mice resulted in depletion of undifferentiated spermatogonial cells and subsequently of differentiated spermatogonia and spermatocytes. In addition, Stra8-cre-driven ablation of Mps1 in male mice led to germ cell loss and fertility reduction. Spermatocytes lacking Mps1 have blocked at the zygotene-to-pachytene transition in the prophase of meiosis I, which may be due to decreased H2B ubiquitination level mediated by MDM2. And the expression of many meiotic genes was decreased, while that of apoptotic genes was increased. Moreover, we also detected increased apoptosis in spermatocytes with Mps1 knockout, which may have been the reason why germ cells were lost. Taken together, our findings indicate that MPS1 is required for mitosis of gonocytes and spermatogonia, differentiation of undifferentiated spermatogonia, and progression of meiosis I in spermatocytes.

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Maintenance of bovine oocytes in prophase of meiosis I by high [cAMP]i

Reproduction ◽

10.1530/jrf.0.1050227 ◽

1995 ◽

Vol 105 (2) ◽

pp. 227-235 ◽

Cited By ~ 44

Author(s):

H. Aktas ◽

M. B. Wheeler ◽

C. F. Rosenkrans ◽

N. L. First ◽

M. L. Leibfried-Rutledge

Keyword(s):

Bovine Oocytes ◽

Meiosis I ◽

Prophase Of Meiosis

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Morphological and histochemical obervations on the ovarian balls of Centrorhynchus corvi (Acanthocephala)

Parasitology ◽

10.1017/s0031182000047879 ◽

1977 ◽

Vol 74 (3) ◽

pp. 243-253 ◽

Cited By ~ 7

Author(s):

V. R. Parshad ◽

S. S. Guraya

Keyword(s):

Growth Phase ◽

Chromatin Structure ◽

Mitotic Division ◽

Nuclear Morphology ◽

Thin Membrane ◽

Third Stage ◽

Functional Units ◽

Yolk Nucleus ◽

Meiosis I ◽

Prophase Of Meiosis

Unlike in other acanthocephalans, the overian balls of Centrorhynchus corvi are complex and are composed of 24–30 ovarian ball units. Each ovarian ball unit consists of three structural and functional units – the oogonial syncytium, developing oogenetic cells and the supporting syncytium – complementary to the ovarian balls of other acanthocephalans. Three metamorphic stages of the nuclei in the oogonial syncytium are described, depending on the nuclear morphology, chromatin structure and appearance of the nucleolus. Third-stage nuclei bulge out at the periphery of the oogonial syncytium and are surrounded by its cytoplasm and a thin membrane. Ultimately these are separated from the oogonial syncytium to from oogonia containing small amounts of cytoplasmic components derived from the oogonial syncytium. Nuclei of the young oogonia, oognia at the budding stage, and 3rd-stage nuclei of the oogonial syncytium all possess nucleoli and are similar also in their nuclear dimensions and cytochemical affinities. Nuclear resemblances, and cytoplasmic similarities of the oogonia and oogonial syncytium with regard to the presence of lipids, RNA and proteins support the concept of the origin of oogonia from the oogonial syncytium.The free oogonia divide mitotically in the cellular zone where they undergo a single mitotic division and the resulting oocytes enter the prophase of meiosis. I. The meiotic primary oocytes in contrast to the permeiotic primary oocytes of other acanthoscephalans enter the growth phase which is closely accompanied by the accumulation of various ooplasmic components such as basophilic yolk nucleus which is composed of RNA, proteins, lipoproteins and phospholipids. Histochemical features of the oogonial and supporting syncytium are described.

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A Wisp3 Cre-knockin Allele Produces Efficient Recombination in Spermatocytes during Early Prophase of Meiosis I

PLoS ONE ◽

10.1371/journal.pone.0075116 ◽

2013 ◽

Vol 8 (9) ◽

pp. e75116 ◽

Cited By ~ 4

Author(s):

Steven Hann ◽

Laura Kvenvold ◽

Brittney N. Newby ◽

Minh Hong ◽

Matthew L. Warman

Keyword(s):

Early Prophase ◽

Meiosis I ◽

Prophase Of Meiosis

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Meiotic CENP-C is a shepherd: bridging the space between the centromere and the kinetochore in time and space

Essays in Biochemistry ◽

10.1042/ebc20190080 ◽

2020 ◽

Vol 64 (2) ◽

pp. 251-261

Author(s):

Jessica E. Fellmeth ◽

Kim S. McKim

Keyword(s):

Chromosome Segregation ◽

New Technologies ◽

Early Prophase ◽

Unique Role ◽

Kinetochore Assembly ◽

M Phase ◽

In Vivo Analysis ◽

Meiosis I

Abstract While many of the proteins involved in the mitotic centromere and kinetochore are conserved in meiosis, they often gain a novel function due to the unique needs of homolog segregation during meiosis I (MI). CENP-C is a critical component of the centromere for kinetochore assembly in mitosis. Recent work, however, has highlighted the unique features of meiotic CENP-C. Centromere establishment and stability require CENP-C loading at the centromere for CENP-A function. Pre-meiotic loading of proteins necessary for homolog recombination as well as cohesion also rely on CENP-C, as do the main scaffolding components of the kinetochore. Much of this work relies on new technologies that enable in vivo analysis of meiosis like never before. Here, we strive to highlight the unique role of this highly conserved centromere protein that loads on to centromeres prior to M-phase onset, but continues to perform critical functions through chromosome segregation. CENP-C is not merely a structural link between the centromere and the kinetochore, but also a functional one joining the processes of early prophase homolog synapsis to late metaphase kinetochore assembly and signaling.

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