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Adele L. Marston 《Genetics》2014,196(1):31-63
Studies on budding yeast have exposed the highly conserved mechanisms by which duplicated chromosomes are evenly distributed to daughter cells at the metaphase–anaphase transition. The establishment of proteinaceous bridges between sister chromatids, a function provided by a ring-shaped complex known as cohesin, is central to accurate segregation. It is the destruction of this cohesin that triggers the segregation of chromosomes following their proper attachment to microtubules. Since it is irreversible, this process must be tightly controlled and driven to completion. Furthermore, during meiosis, modifications must be put in place to allow the segregation of maternal and paternal chromosomes in the first division for gamete formation. Here, I review the pioneering work from budding yeast that has led to a molecular understanding of the establishment and destruction of cohesion. 相似文献
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本文以藓类植物的幼嫩孢蒴及茎尖为材料,对产于中国秦岭的六种提灯藓的染色体进行了观察计数。首次报道了M.pseudolycopodioides的染色体数目为n=6;M.marginatum和M.lycopoidioides的染色体数分别为n=12及n=6,与前人报道的结果一致;M.Laevinerve、M.heterophyllum以及M.thomsoii的染色体数目均为n=6,与前人的报道不完全相同。本文旨在为本属的研究提供一定的细胞学资料。 相似文献
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Aurora A, meiosis and mitosis 总被引:6,自引:0,他引:6
Crane R Gadea B Littlepage L Wu H Ruderman JV 《Biology of the cell / under the auspices of the European Cell Biology Organization》2004,96(3):215-229
The Aurora family kinases are pivotal to the successful execution of cell division. Together they ensure the formation of a bipolar mitotic spindle, accurate segregation of chromosomes and the completion of cytokinesis. They are also attractive drug targets, being frequently deregulated in cancer and able to transform cells in vitro. In this review, we summarize current knowledge about the three family members, Aur-A, Aur-B and Aur-C. We then focus on Aur-A, its roles in mitotic progression, and its emerging roles in checkpoint control pathways. Aur-A activity can be controlled at several levels, including phosphorylation, ubiquitin-dependent proteolysis and interaction with both positive regulators, such as TPX2, and negative ones, like the tumor suppressor protein p53. In addition, work in Xenopus oocytes and early embryos has revealed a second role for Aur-A, directing the polyadenylation-dependent translation of specific mRNAs important for cell cycle progression. This function extends to post-mitotic neurons, and perhaps even to cycling somatic cells. 相似文献
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利用整体压片法 ,对分别隶属于球角科和长角科的两种跳虫似微小球角 (Hypogastruraadex ilis (Stach ,196 4 ) )和曲毛裸长 (SinellacurvisetaBrook 1889)的染色体进行了首次观察。发现似微小球角单倍染色体数目n =7,雄性有 13条染色体 ,雌性有 14条 ,为XO型性别决定 ;曲毛裸长n =6 ,雄性 2n =11,雌性 2n =12 ,同样为XO型性别决定。还记述了雄性似微小球角的减数分裂过程 :在分裂前期 ,同源染色体进行配对 ;部分同源染色体发生交叉 ,部分仅末端相连 ;早后期Ⅰ ,当常染色体向两极移动时 ,性染色体仍滞后于赤道板中央。 相似文献
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用自行的多级光学放大系统,观察到染色体上15nm大小的细微结构,用以研究致密状态的中期染色体超级结构,结合细胞化学技术,用特异性染色显示DNA-核蛋白、酸性骨架蛋白在染色体上的构象,本文发表了家猪染色体超级结构的天然形态-螺旋构型照片,描述了染色体螺旋结构的特征及其参数,提出了染色体超级结构的螺旋模型。 相似文献
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黄瓜花粉母细胞减数分裂行为的研究 总被引:17,自引:1,他引:17
研究了华北型、华南型和西南型黄瓜花粉母细胞的减数分裂行为,发现黄瓜细胞核减数分裂的同步性较高,细胞质是同时型分裂。在细胞核分裂的过程中,核仁在前期Ⅰ到中期Ⅰ逐渐消失,在前期Ⅰ再次出现,随后消失;染色体在前期Ⅰ到中期Ⅰ逐渐收缩,变得清晰,至末期Ⅰ解螺旋,变得模糊,在前期I再次清晰。不同生态型黄瓜终变期的染色体构型均以环状二价体为主。在前期Ⅰ和前期Ⅰ,西双版纳黄瓜的核仁都相应地比另外两种生态型黄瓜品种的多,在后期Ⅰ还偶尔出现染色体桥,显示了西双版纳黄瓜变种的特殊性。研究还发现寒冷的气候条件下栽培黄瓜都能够形成高频率的多分体,推测其形成很可能与低温逆境有关。 相似文献
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Summary The fidelity of mitotic chromosome transmission in Schizosaccharomyces pombe was estimated quantitatively by using cycloheximide resistance as a means to select cells that had undergone chromosome loss or nondisjunction. We aimed to investigate the connection between recombination and mitotic chromosome stability. A number of mutants defective in mitotic recombination such as cdc17-L16, rec59-72, and rec50-25 were tested and in these an approximately ten fold elevation of mitotic haploidization rate was found compared with controls. Our data suggest that recombination is important in controlling the maintenance of chromosomes during mitosis. 相似文献
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M S Halleck K Lumley-Sapanski J A Reed A P Iyer A M Mastro R A Schlegel 《FEBS letters》1984,167(2):193-198
A number of protein kinases have been separated and identified in extracts from mitotic and interphase culture cells and from mature and immature amphibian oocytes using nondenaturing polyacrylamide gel electrophoresis followed by in situ phosphorylation assays. Certain of these protein kinase activities appear to correlate with the biological activity of extracts, assayed by their ability to induce meiotic maturation following injection into Xenopus oocytes. These results are consistent with the notion that protein phosphorylation/dephosphorylation may be integral to the mechanisms of both nuclear membrane breakdown and chromosome condensation, events common and distinctive to mitosis and meiosis. 相似文献
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More than 100 strains ofLemna paucicostata Hegelm. collected from various localities in Japan were classified into 4 types according to the criterion of Yukawa and
Takimoto (1976). N-1 type strains are widely distributed in Hokkaido, Honshu, Shikoku and Kyushu, N-2 type strains only in
the area on the Japan Sea side of north Japan, K type strain only at the campus of Kyoto University, and S type strains in
southern Japan.
Numbers of chromosomes in somatic cells of N-1, N-2, K and S type strains were 2n=66–84, 40, 50 and 40, respectively. In N-2
and S type strains, all chromosomes (20 bivalent chromosomes) were lined up on the equatorial plate at metaphase of the first
meiotic division (MI). However, in N-1 type strains, several chromosomes, and in the K type strain, more chromosomes were
away from the equatorial plate at MI. Pollen fertility was 60–70%, higher than 90%, 0% and higher than 90%, in N-1, N-2, K
and S type strains, respectively. 相似文献
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A. Plourde G. Fedak C. A. St-Pierre A. Comeau 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(1):45-48
Summary Two hybrid embryos of intergeneric origin between Triticum aestivum cv Fukuho (2n=6x=42, AABBDD) and Psathyrostachys juncea (2n=2x=14, NN) were successfully rescued. One hybrid plant had the expected chromosome number of 28 (ABDN), whereas the second plant had 35 chromosomes. The average meiotic chromosome pairing in the 35-chromosome hybrid was 21.87 univalents + 6.38 bivalents + 0.11 trivalents + 0.009 quadrivalents, which indicates that two copies of the N genome were present. Chromosome pairing in the 28-chromosome hybrid was low (1.35 bivalents), and pointed out the lack of homology between the wheat genomes and the P. juncea genome. These new hybrids showed some necrosis and chlorosis, which caused severe floral abortion in the plant that had 35 chromosomes. These problems became gradually less severe after 18 months.Contrib. no. 372 相似文献
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Brachet E Sommermeyer V Borde V 《Biology of the cell / under the auspices of the European Cell Biology Organization》2012,104(2):51-69
Meiotic recombination lies at the heart of sexual reproduction. It is essential for producing viable gametes with a normal haploid genomic content and its dysfunctions can be at the source of aneuploidies, such as the Down syndrome, or many genetic disorders. Meiotic recombination also generates genetic diversity that is transmitted to progeny by shuffling maternal and paternal alleles along chromosomes. Recombination takes place at non-random chromosomal sites called 'hotspots'. Recent evidence has shown that their location is influenced by properties of chromatin. In addition, many studies in somatic cells have highlighted the need for changes in chromatin dynamics to allow the process of recombination. In this review, we discuss how changes in the chromatin landscape may influence the recombination map, and reciprocally, how recombination events may lead to epigenetic modifications at sites of recombination, which could be transmitted to progeny. 相似文献
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Wilson PG 《Cell biology international》2005,29(5):360-369
Cytokinesis partitions a centrosome to each daughter cell at cell division that will duplicate and assemble a bipolar spindle in the subsequent M phase. Cytokinesis is incomplete in proliferating germ cells in Drosophila and cytoplasmic channels connect sibling germ cells. Although centrosomes are essential to male fertility, the molecular mechanism that retains centrosomes in parental germ cells is not known. Cortical cytoplasmic structures known as fusomes extend through ring canals and connect cells within the cyst. Fusome assembly in males requires function of hu-li tai-shao (hts), an adducin like protein found in fusomes and in the cortical membrane cytoskeleton of somatic cells. This work used immunological and cytological methods to place hts mutants in an allelic series. Male fertile hts mutants express hts protein and generate apparently normal or fragmented fusomes. A male sterile allele does not express hts protein or show fusome structures. Gonial cells in all hts mutants showed 2 centrosomes and mitotic spindles were bipolar. Yet, primary spermatocytes, with and without fusome structures, frequently contained too many or too few centrosomes. Although spindle structures were not found in spermatocytes without centrosomes, meiotic spermatocytes with centrosomes generated bipolar, monopolar, and multipolar spindles. Collectively, these results indicate that hts function is necessary for centrosome inheritance in spermatocytes as well as for male fertility. 相似文献
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Gabriel Guilloux Romain Gibeaux 《Biology of the cell / under the auspices of the European Cell Biology Organization》2020,112(12):369-382
The spindle is crucial for cell division by allowing the faithful segregation of replicated chromosomes to daughter cells. Proper segregation is ensured only if microtubules (MTs) and hundreds of other associated factors interact to assemble this complex structure with the appropriate architecture and size. In this review, we describe the latest view of spindle organisation as well as the molecular gradients and mechanisms underlying MT nucleation and spindle assembly. We then discuss the overlapping physical and molecular constraints that dictate spindle morphology, concluding with a focus on spindle size regulation. 相似文献
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The quadripolar microtubule system (QMS) is a complex array that is associated with predivision establishment of quadripolarity
in sporocytes of lower plants (bryophytes and lycopsids). The QMS unerringly predicts the polarity of the two meiotic divisions
and plays a central role in development of both the mitotic apparatus (MA) and cytokinetic apparatus (CA) which together accomplish
quadripartitioning of the sporocyte into four haploid spores. The QMS is typically, but not exclusively, associated with monoplastidy
and precocious quadrilobing of the cytoplasm. In early meiotic prophase the single plastid divides and the resultant plastids
migrate so that either the tips of two plastids or the four plastids resulting from a second division are located in the future
spore domains. Microtubules that emanate from the plastid tips or from individual plastids in the spore domains interact in
the future planes of cytokinesis and give rise to the QMS. The QMS, which encages the prophase nucleus, consists of at least
four and usually six (when spore domains are in tetrahedral arrangement) bipolar spindle-like arrays of microtubules presumably
with minus ends at plastids in spore domains and plus ends interacting in the future plane of cytokinesis. Each of the six
arrays is essentially like the single axial microtubule system (AMS) that intersects the division site and is transformed
into the spindle in monoplastidic mitosis in hornworts. As comparative data accumulate, it appears that the AMS is not unique
to monoplastidic cell division but instead represents a basic microtubule arrangement that survives as spindle and phragmoplast
in cell division of higher plants. 相似文献
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Summary The effect of taxol, an inhibitor of microtubule degradation, on the seminiferous epithelium was studied. Taxol arrested spermatogenesis at metaphase in both mitotic and meiotic germ cell division. Microtubules were seen to accumulate, especially in the cytoplasm of the spermatogonia, and also in the early spermatids and Sertoli cells. No microtubule accumulation was observed in germ cells during meiotic prophase. Formation of the flagellum was affected in developing spermatids. Peculiar lamellar structures, probably derived from degenerating mitochondria, were seen in the cytoplasm of late spermatids and Sertoli cells.The results are compared with the effects of other mitotic inhibitors such as colchicine and vinca alcaloids. 相似文献