Repairing DNA double-strand breaks (DSBs) with homologous chromosomes as templates is the hallmark of meiosis. The critical outcome of meiotic homologous recombination is crossovers, which ensure faithful chromosome segregation and promote genetic diversity of progenies. Crossover patterns are tightly controlled and exhibit three characteristics: obligatory crossover, crossover interference, and crossover homeostasis. Aberrant crossover patterns are the leading cause of infertility, miscarriage, and congenital disease. Crossover recombination occurs in the context of meiotic chromosomes, and it is tightly integrated with and regulated by meiotic chromosome structure both locally and globally. Meiotic chromosomes are organized in a loop-axis architecture. Diverse evidence shows that chromosome axis length determines crossover frequency. Interestingly, short chromosomes show different crossover patterns compared to long chromosomes. A high frequency of human embryos are aneuploid, primarily derived from female meiosis errors. Dramatically increased aneuploidy in older women is the well-known "maternal age effect." However, a high frequency of aneuploidy also occurs in young women, derived from crossover maturation inefficiency in human females. In addition, frequency of human aneuploidy also shows other age-dependent alterations. Here, current advances in the understanding of these issues are reviewed, regulation of crossover patterns by meiotic chromosomes are discussed, and issues that remain to be investigated are suggested.
Cell Division/physiology* ; Chromosome Segregation/physiology* ; Humans ; Meiosis/genetics* ; Recombination, Genetic

The synaptonemal complex (SC) is a meiosis-specific proteinaceous macromolecular structure that assembles between paired homologous chromosomes during meiosis in various eukaryotes. The SC has a highly conserved ultrastructure and plays critical roles in controlling multiple steps in meiotic recombination and crossover formation, ensuring accurate meiotic chromosome segregation. Recent studies in different organisms, facilitated by advances in super-resolution microscopy, have provided insights into the macromolecular structure of the SC, including the internal organization of the meiotic chromosome axis and SC central region, the regulatory pathways that control SC assembly and dynamics, and the biological functions exerted by the SC and its substructures. This review summarizes recent discoveries about how the SC is organized and regulated that help to explain the biological functions associated with this meiosis-specific structure.
Animals ; Chromosome Segregation ; Meiosis/physiology* ; Synaptonemal Complex/physiology*

Cell Nucleus Division ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Diagnosis, Differential ; Female ; Humans ; Leiomyoma ; metabolism ; pathology ; physiopathology ; Smooth Muscle Tumor ; metabolism ; pathology ; physiopathology ; Uterine Neoplasms ; metabolism ; pathology ; physiopathology

OBJECTIVETo investigate the tumorigenic mechanisms of human leukemia cell line HL60-n in nude mice.

METHODSDifferent clone strains of HL60-n cells were established by limited dilution and their biological features were compared with parental HL-60 cells.

RESULTSThe colony yields in soft agar, especially the large colony yields of the high tumorigenic clone strains HL60-n/A, HL60-n/B were significantly higher than that of the HL-60 cells (P < 0.01). There was no significant difference between the low tumorigenic clone strains HL60-n/E, HL60-n/F and the HL-60 cells. Ultrastructurally, the nucleus was highly abnormal, the euchromatic element of nuclear chromatin increased, the heterochromatin sparse, and the microfilaments in cytoplasm increased and disarranged in the high tumorigenic cells as compared with HL-60 cells. Cell cycle analysis by flow cytometer showed higher S phase fractions in the high tumorigenic cells. The killing activities of NK cells to the high tumorigenic clone strains were significant lower than to the contrast (P < 0.01). The histopathological features produced by the low tumorigenic leukemia cells showed that there were many inflammatory cells infiltrated, the majority of them were lymphocytes, and many tumor cells were killed especially in vessel abundant areas. By contrast, there were few inflammatory cells infiltrated in the tumors produced by the high tumorigenic cell strains.

CONCLUSIONThe mechanism of the high tumorigenic activity of the HL60-n cell line involved higher colony yields in soft agar, higher S phase fraction, decreased susceptibility to NK cell killing, and the inhibition of the host immunity.

Animals ; Carcinogenicity Tests ; Cell Division ; physiology ; Cell Nucleus ; pathology ; ultrastructure ; Disease Models, Animal ; HL-60 Cells ; Humans ; Killer Cells, Natural ; cytology ; immunology ; Leukemia ; pathology ; physiopathology ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Neoplasm Transplantation ; pathology ; Tumor Stem Cell Assay

OBJECTIVE: Recently it has been proposed that stem cells may be associated with the pathogenesis of endometriosis. The purposes of this study are to investigate whether the eutopic endometrial cells of women with or without endometriosis show the characteristics of stem cells in vitro and have a difference of the expressions of the undifferentiated stem cell markers as OCT-4 and CXCR4. METHODS: A total of 6 women with advanced endometriosis and a total of 10 women without endometriosis, adenomyosis or leiomyoma were included in this study. The eutopic endometrial cells, which were obtained from the menstrual blood at menstrual cycle day 2 to 4, were cultured in vitro for approximately 2 weeks, subsequently the putative very small stem cells were separated by Percoll density gradient method and were cultured. The expressions of OCT-4 and CXCR4 were analyzed by real time RT-PCR. RESULTS: The eutopic endometrial cells of the group of endometriosis compared with the control group showed the different morphological characteristics in vitro; more commonly heterogeneous supportive cells, very small round cells less than 3 micrometer and 5~15 micrometer sized hyperchromatic round cells. After the separation of very small round cells by Percoll density gradient method, these cells showed the several characteristics of stem cells; self-renewal, asymmetric cell division, colony formation and embryoid body-like formation. Also These cells showed the similar characteristics of very small embryonic-like stem cells; the mobile cells smaller than erythrocyte, the cell migration or adhesion to supportive cells, the sphere formation by cell aggregation and the formation of new differentiated cell by cell fusion. The expressions of OCT-4 and CXCR4 in the group of endometriosis are respectively 5.66 times and 17.69 times as high as the control group (P<0.05). CONCLUSION: The very small round cells less than 3 micrometer and 5~15 micrometer sized hyperchromatic round cells, which showed the several characteristics of stem cells in vitro, were more common in eutopic endometrial cells of patients with endometriosis and the expressions of OCT-4 and CXCR4 were significantly higher. This study suggests that stem cells might play a key role in the pathogenesis of endometriosis and OCT-4 and CXCR4 might be used as a tool for diagnosis or follow-up.
Adenomyosis ; Asymmetric Cell Division ; Cell Aggregation ; Cell Fusion ; Cell Movement ; Endometriosis ; Endometrium ; Erythrocytes ; Female ; Humans ; Leiomyoma ; Menstrual Cycle ; Povidone ; Silicon Dioxide ; Stem Cells

BACKGROUND: Adult neural stem cells have the potential for self-renewal and differentiation into multiple cell lineages via symmetric or asymmetric cell division. Preso1 is a recently identified protein involved in the formation of dendritic spines and the promotion of axonal growth in developing neurons. Preso1 can also bind to cell polarity proteins, suggesting a potential role for Preso1 in asymmetric cell division. METHODS: To investigate the distribution of Preso1, we performed immunohistochemistry with adult mouse brain slice. Also, polarized distribution of Preso1 was assessed by immunocytochemistry in cultured neural stem cells. RESULTS: Immunoreactivity for Preso1 (Preso1-IR) was strong in the rostral migratory stream and subventricular zone, where proliferating transit-amplifying cells and neuroblasts are prevalent. In cultured neural stem cells, Preso1-IR was unequally distributed in the cell cytosol. We also observed the distribution of Preso1 in the subgranular zone of the hippocampal dentate gyrus, another neurogenic region in the adult brain. Interestingly, Preso1-IR was transiently observed in the nuclei of doublecortin-expressing neuroblasts immediately after asymmetric cell division. CONCLUSION: Our study demonstrated that Preso1 is asymmetrically distributed in the cytosol and nuclei of neural stem/progenitor cells in the adult brain, and may play a significant role in cell differentiation via association with cell polarity machinery.
Adult* ; Animals ; Asymmetric Cell Division ; Axons ; Brain ; Cell Differentiation ; Cell Lineage ; Cell Polarity ; Cytosol ; Dendritic Spines ; Dentate Gyrus ; Humans ; Immunohistochemistry ; Mice ; Neural Stem Cells ; Neurons ; Rivers

Animals ; Biomarkers, Tumor ; genetics ; metabolism ; Cell Nucleus Division ; Cystadenocarcinoma, Serous ; classification ; genetics ; metabolism ; pathology ; Female ; Humans ; Mutation ; Neoplasm Grading ; Ovarian Neoplasms ; classification ; genetics ; metabolism ; pathology ; Proto-Oncogene Proteins B-raf ; genetics ; metabolism ; Tumor Suppressor Protein p53 ; genetics ; metabolism

The maturation process of mammalian oocytes accompanies an extensive rearrangement of the cytoskeleton and associated proteins. As this process requires a delicate interplay between the cytoskeleton and its regulators, it is often targeted by various external and internal adversaries that affect the congression and/or segregation of chromosomes. Asymmetric cell division in oocytes also requires specific regulators of the cytoskeleton, including formin-2 and small GTPases. Recent literature providing clues regarding how actin filaments and microtubules interact during spindle migration in mouse oocytes are highlighted in this review.
Actin Cytoskeleton ; Animals ; Asymmetric Cell Division ; Cytoskeleton ; GTP Phosphohydrolases ; Humans ; Mice ; Microtubules ; Monomeric GTP-Binding Proteins ; Nerve Tissue Proteins ; Oocytes ; Proteins

An increasing number of monopartite begomoviruses are being identified that a satellite molecule (DNAbeta) is required to induce typical symptoms in host plants. DNAbeta encodes a single gene (termed betaC1) encoded in the complementary-sense. We have produced transgenic Nicotiana benthamiana and N. tabacum plants expressing the betaC1 gene of a DNAbeta associated with Tomato yellow leaf curl China virus (TYLCCNV), under the control of the Cauliflower mosaic virus 35S promoter. Transgenic plants expressing betaC1 showed severe developmental abnormalities in both species. Microscopic analysis of sections of both transgenic and non-transgenic N. tabacum leaves showed abnormal outgrowths of transgenic N. tabacum to be due to disorganized cell division (hyperplasia) of spongy and palisade parenchyma. Immuno-gold labeling of sections with a polyclonal antibody against the betaC1 protein showed that the betaC1 protein accumulated in the nuclei of cells. The possible biological function of the betaC1 protein was discussed.
Cell Division ; physiology ; Cell Nucleus ; genetics ; metabolism ; ultrastructure ; Cells, Cultured ; DNA, Viral ; genetics ; Geminiviridae ; genetics ; Plant Diseases ; genetics ; virology ; Plant Leaves ; cytology ; genetics ; growth & development ; metabolism ; Plants, Genetically Modified ; growth & development ; metabolism ; Recombinant Proteins ; metabolism ; Tobacco ; cytology ; growth & development ; metabolism ; ultrastructure ; Viral Proteins ; genetics ; metabolism

BACKGROUND AND OBJECTIVES: Despite significant improvement in the field of angioplasty, restenosis remains a major obstacle to the long-term success of the procedure. Radiation can effectively inhibit neointimal hyperplasia by causing the arrest of mitosis during cell division and limiting proliferation by reducing the number of regenerating clonal progenitors. Balloon injury could induce the cell adhesion molecule, ICAM-1 and VCAM-1, on SMCs and regenerating endothelial cells (ECs). ICAM-1 and/or VCAM-1 may play a role in the progression of neointimal hyperplasia induced by balloon injury and external radiation may effectively inhibit neointimal hyperplasia by attenuating their expression. The purpose of this study was to examine the effect of external radiation against ICAM-1 and VCAM-1 on neointimal hyperplasia after balloon injury in rat carotid arteries. MATERIAL AND METHODS: A standardized carotid balloon catheter arterial injury was produced in 51 rats and external beam radiation with doses from 5-20 Gy were delivered in 28 rats (radiation treated group) at 24 hours after injury. To investigate the effect of the external radiation on neointimal hyperplasia, the intima area and the intima/medial area of arteries were measured at day 14 after injury. The expressions of ICAM-1 and VCAM-1 at day 2, day 7, and day 10 after injury were studied in control group and radiation treated group by immunohistochemistry. RESULTS: Means of intimal area and intima/medial ratio in radiation treated group were significantly lower than those in control group and significantly reduced with increasing radiation dosage. At day 2 after injury, medial SMCs of injury group extensively expressed ICAM-1, while it was focally expressed with 10 Gy radiation treated group. At day 7 and day 10 after injury, ICAM-1 expression on medial SMCs was attenuated and neointimal ICAM-1 expression was increased. As compared with control group, ICAM-1 expression after radiation was weak and focal just around the internal elastic lamina. At 2 days after injury, medial SMCs moderately expressed VCAM-1, which was weakly and focally expressed with 10 Gy radiation treated group. At day 7 and day 10 after injury, focal expression of VCAM-1 was noted around the internal elastic lamina, but there was no VCAM-1 expression on neointima with radiation. CONCLUSION: External radiation after carotid arterial injury may potentially inhibit SMC proliferation and neointimal hyperplasia, and balloon injury-induced or upregulated expressions of ICAM-1 and VCAM-1 may be attenuated with external radiation.
Angioplasty ; Animals ; Arteries ; Carotid Arteries ; Catheters ; Cell Adhesion* ; Cell Division ; Endothelial Cells ; Hyperplasia* ; Immunohistochemistry ; Intercellular Adhesion Molecule-1* ; Mitosis ; Neointima ; Radiation Dosage ; Rats* ; Vascular Cell Adhesion Molecule-1