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oocyte meiosis

Ya Xin Yao, Yong Fu La, Ran Di, Qiu Yue Liu, Wen Ping Hu, Xiang Yu Wang, Ming Xing Chu
Single-cell whole genome amplification (WGA) is a new technology, which can amplify small amounts of DNA from single cell and obtain the high coverage whole genome DNA template for revealing cell heterogeneity. Single cell WGA methods mainly include primer extension preamplification PCR (PEP-PCR), degenerate oligonucleotide primed PCR (DOP-PCR), multiple displacement amplification (MDA), and multiple annealing and looping-based amplification cycles (MALBAC). In this review, we describe the principles and applications of different single cell genome wide amplification, and we evaluate and compare their amplification efficiency, including the coverage of genome, homogeneity, reproducibility, and detection power of single-nucleotide variants (SNV) and copy number variants (CNV)...
August 16, 2018: Yi Chuan, Hereditas
Jun-Chao Wang, Ying Geng, Ying Han, Hai-Ning Luo, Yun-Shan Zhang
Cyclic adenosine monophosphate (cAMP) is an important secondary messenger that has long been recognized to control the initiation of meiosis through the activation of protein kinase A (PKA) in mammalian oocytes. However, PKA is not the only target for cAMP. Recent studies on cAMP-dependent and PKA-independent pathways suggest that Ras-related protein-1 (Rap1) is activated through its cAMP-responsive guanine exchange factors (cAMP-GEFs), which comprises the involvement of exchange proteins directly activated by cAMP (Epac) in various cellular processes...
August 2018: Experimental and Therapeutic Medicine
Jian Li, Ji-Xin Tang, Jin-Mei Cheng, Bian Hu, Yu-Qian Wang, Batool Aalia, Xiao-Yu Li, Cheng Jin, Xiu-Xia Wang, Shou-Long Deng, Yan Zhang, Su-Ren Chen, Wei-Ping Qian, Qing-Yuan Sun, Xing-Xu Huang, Yi-Xun Liu
Mammalian oocytes are arrested at the prophase of the first meiotic division for months and even years, depending on species. Meiotic resumption of fully grown oocytes requires activation of M-phase-promoting factor (MPF), which is composed of Cyclin B1 and cyclin-dependent kinase 1 (CDK1). It has long been believed that Cyclin B1 synthesis/accumulation and its interaction with CDK1 is a prerequisite for MPF activation in oocytes. In this study, we revealed that oocyte meiotic resumption occurred in the absence of Cyclin B1...
August 10, 2018: Journal of Cell Biology
Feng Tang, Meng-Hao Pan, Yujie Lu, Xiang Wan, Yu Zhang, Shao-Chen Sun
Kif4a, a member of the kinesin superfamily, has been reported to participate in a series of cellular processes such as chromosome condensation and cytokinesis during mitosis. However, the roles of KIF4a in meiosis are still unknown. In present study we found that the Kif4a protein expression decreased in maternal aged mouse oocytes. We then explored the roles of Kif4a in mouse oocyte meiosis by knockdown analysis. Kif4a was enriched at the spindle during mouse oocyte maturation. By specific knock down of the Kif4a using morpholino microinjection, we found that the disruption of Kif4a caused the failure of polar body extrusion...
August 2018: Aging and Disease
Pierre Romé, Hiroyuki Ohkura
The meiotic spindle in oocytes is assembled in the absence of centrosomes, the major microtubule nucleation sites in mitotic and male meiotic cells. A crucial, yet unresolved question in meiosis is how spindle microtubules are generated without centrosomes and only around chromosomes in the exceptionally large volume of oocytes. Here we report a novel oocyte-specific microtubule nucleation pathway that is essential for assembling most spindle microtubules complementarily with the Augmin pathway. This pathway is mediated by the kinesin-6 Subito/MKlp2, which recruits the γ-tubulin complex to the spindle equator to nucleate microtubules in Drosophila oocytes...
August 7, 2018: Journal of Cell Biology
Meghan L Ruebel, Peter Z Schall, Uros Midic, Kailey A Vincent, Benjamin Goheen, Catherine A VandeVoort, Keith E Latham
STUDY QUESTION: Which different pathways and functions are altered in rhesus monkey oocytes that fail to mature after an ovulatory stimulus? SUMMARY ANSWER: FTM oocytes complete a large portion of the transition in transcriptome composition associated with normal maturation, but also manifest numerous differences that indicate incomplete transcriptional repression and cytoplasmic maturation affecting multiple processes. WHAT IS KNOWN ALREADY: Oocyte maturation defects contribute to unexplained female infertility...
August 3, 2018: Molecular Human Reproduction
Marion Manil-Ségalen, Małgorzata Łuksza, Joanne Kanaan, Véronique Marthiens, Simon I R Lane, Keith T Jones, Marie-Emilie Terret, Renata Basto, Marie-Hélène Verlhac
Mouse female meiotic spindles assemble from acentriolar microtubule-organizing centers (aMTOCs) that fragment into discrete foci. These are further sorted and clustered to form spindle poles, thus providing balanced forces for faithful chromosome segregation. To assess the impact of aMTOC biogenesis on spindle assembly, we genetically induced their precocious fragmentation in mouse oocytes using conditional overexpression of Plk4, a master microtubule-organizing center regulator. Excessive microtubule nucleation from these fragmented aMTOCs accelerated spindle assembly dynamics...
August 6, 2018: Journal of Cell Biology
Chunling Li, Feiyang Diao, Danhong Qiu, Manxi Jiang, Xiaoyan Li, Longsen Han, Ling Li, Xiaojing Hou, Juan Ge, Xianghong Ou, Jiayin Liu, Qiang Wang
SET-domain-containing 2 (SETD2), a member of the histone lysine methyltransferase family, has been reported to be involved in multiple biological processes. However, the function of SETD2 during oocyte maturation has not been addressed. In this study, we find that mouse oocytes are incapable of progressing through meiosis completely once SETD2 is specifically depleted. These oocytes present an abnormal spindle morphology and deficient chromosome movement, with disrupted kinetochore-microtubule attachments, consequently producing aneuploidy eggs...
August 5, 2018: Journal of Cellular Physiology
Jin Chen, Pin Su, Pengyun Chen, Qiong Li, Xiaoling Yuan, Zhi Liu
BACKGROUND: Plant anther development is a systematic and complex process precisely controlled by genes. Regulation genes and their regulatory mechanisms for this process remain elusive. In contrast to numerous researches on anther development with respect to mRNAs or miRNAs in many crops, the association analysis combining both omics has not been reported on cotton anther. RESULTS: In this study, the molecular mechanism of cotton anther development was investigated with the employment of association analysis of transcriptome and small RNA sequencing during the predefined four stages of cotton anther development, sporogenuous cell proliferation (SCP), meiotic phase (MP), microspore release period (MRP) and pollen maturity (PM)...
August 3, 2018: BMC Plant Biology
Xiaotong Wu, Weimin Shen, Bingjie Zhang, Anming Meng
Oocytes, the irreplaceable gametes for generating a new organism, are matured in the ovary of living female animals. It is unknown whether any genetic manipulations can be applied to immature oocytes inside the living ovaries. As a proof-of-concept, we here demonstrate genetic amendments of zebrafish immature oocytes within the ovary. Oocyte microinjection in situ (OMIS) stimulates tissue repair responses, but some of microinjected immature oocytes are matured, ovulated and fertilizable. By OMIS-mediated Cas9 approach, ntla and gata5 loci of oocytes arrested at prophase I of meiosis are successfully edited before fertilization...
July 28, 2018: Journal of Molecular Cell Biology
Melanie L Walls, Roger J Hart
In vitro maturation (IVM) is an in vitro fertilisation (IVF) technique modified to collect immature oocytes from antral follicles, with the final stages of meiosis completed during in vitro culture. The primary benefit of IVM is that it reduces gonadotrophin stimulation in the patient, thereby eliminating the risk of ovarian hyperstimulation syndrome (OHSS) in high-risk patients such as those with polycystic ovaries (PCO) and polycystic ovary syndrome (PCOS). IVM has additional benefits for fertility preservation, particularly in oncofertility patients...
June 28, 2018: Best Practice & Research. Clinical Obstetrics & Gynaecology
Yue Xie, Bin Wu, Yecheng Jin, Aizhen Zhang, Xiaoyang Sun, Xinyan Zhang, Xiaotong Gao, Ran Dong, Huashun Li, Jiangang Gao
The stimulatory heterotrimeric Gs protein alpha subunit (Gs α) is a ubiquitous guanine nucleotide-binding protein that regulates the intracellular cAMP signaling pathway and consequently participates in a wide range of biological events. In the reproductive system, despite Gs α being associated with oocyte meiotic arrest in vitro, the exact role of Gs α in female fertility in vivo remains largely unknown. Here, we generated oocyte-specific Gs α knockout mice by using the Cre/LoxP system. We observed that the deletion of Gs α caused complete female infertility...
July 17, 2018: Experimental Cell Research
M Rizzo, K D Ducheyne, C Deelen, M Beitsma, S Cristarella, M Quartuccio, T A E Stout, M de Ruijter-Villani
BACKGROUND: Advanced mare age is associated with declining fertility and an increased risk of early pregnancy loss. Compromised oocyte quality is probably the primary reason for reduced fertility, but the defects predisposing to embryonic death are unknown. In women, advanced age predisposes to chromosome segregation errors during meiosis, which lead to embryonic aneuploidy and a heightened risk of miscarriage. OBJECTIVES: To evaluate the effect of advanced mare age on chromosome alignment and meiotic spindle morphology in in vitro-matured (IVM) oocytes...
July 19, 2018: Equine Veterinary Journal
Zijing Zhang, Amber R Krauchunas, Stephanie Huang, Mariana F Wolfner
Egg activation is essential for the successful transition from a mature oocyte to a developmentally competent egg. It consists of a series of events including the resumption and completion of meiosis, initiation of translation of some maternal mRNAs and destruction of others, and changes to the vitelline envelope. This major change of cell state is accompanied by large scale alteration in the oocyte's phosphoproteome. We hypothesize that the cohort of proteins that are subject to phosphoregulation during egg activation are functionally important for processes before, during, or soon after this transition, potentially uniquely or as proteins carrying out essential cellular functions like those they do in other (somatic) cells...
July 16, 2018: G3: Genes—Genomes—Genetics
Dan Zhang, Yifeng Liu, Zhou Zhang, Pingping Lv, Yun Liu, Jingyi Li, Yiqing Wu, Runjv Zhang, Yun Huang, Gufeng Xu, Yeqing Qian, Yuli Qian, Songchang Chen, Chenming Xu, Jun Shen, Linling Zhu, Kai Chen, Bo Zhu, Xiaoqun Ye, Yuchan Mao, Xingsheng Bo, Caiyun Zhou, Tingting Wang, Dianfu Chen, Weijun Yang, Yajing Tan, Yang Song, Daizhan Zhou, Jianzhong Sheng, Huijuan Gao, Yimin Zhu, Meigen Li, Liping Wu, Lin He, Hefeng Huang
Primary ovarian insufficiency (POI) leads to infertility and premature menopause in young women. The genetic etiology of this disorder remains unknown in most patients. Using whole-exome sequencing of a large Chinese POI pedigree, we identified a heterozygous 5 bp deletion inducing a frameshift in BNC1, which is predicted to result in nonsense mediated decay or a truncated BNC1 protein. Sanger sequencing identified another BNC1 missense mutation in four of 82 idiopathic POI patients, and the mutation was absent in 332 healthy controls...
July 16, 2018: Human Molecular Genetics
Xing Duan, Shao-Chen Sun
During mitosis, cells undergo symmetrical cell division, while oocyte meiotic maturation undergoes two consecutive, asymmetric divisions that generate a totipotent haploid oocyte and two small polar bodies not involved in DNA replication. This specialized division allows most maternal components be maintained in the oocytes for early embryo development. Nuclear positioning, germinal vesicle breakdown, spindle migration, spindle rotation, chromosome segregation, and polar body extrusion are the most critical cellular processes during oocyte meiosis I and II, and a growing number of studies primarily using the mouse oocyte model revealed that actin filaments were critical for these processes, especially for spindle migration...
July 13, 2018: Biology of Reproduction
Ingrid Carvacho, Matthias Piesche, Thorsten J Maier, Khaled Machaca
The proper maturation of both male and female gametes is essential for supporting fertilization and the early embryonic divisions. In the ovary, immature fully-grown oocytes that are arrested in prophase I of meiosis I are not able to support fertilization. Acquiring fertilization competence requires resumption of meiosis which encompasses the remodeling of multiple signaling pathways and the reorganization of cellular organelles. Collectively, this differentiation endows the egg with the ability to activate at fertilization and to promote the egg-to-embryo transition...
2018: Frontiers in Cell and Developmental Biology
Oliver J Gruss
Sexual reproduction requires the generation of gametes, which are highly specialised for fertilisation. Female reproductive cells, oocytes, grow up to large sizes when they accumulate energy stocks and store proteins as well as mRNAs to enable rapid cell divisions after fertilisation. At the same time, metazoan oocytes eliminate their centrosomes, i.e., major microtubule-organizing centres (MTOCs), during or right after the long growth phases. Centrosome elimination poses two key questions: first, how can the centrosome be re-established after fertilisation? In general, metazoan oocytes exploit sperm components, i...
July 10, 2018: Cells
Dániel Horányi, Lilla Éva Babay, Balázs Győrffy, Gyula Richárd Nagy
Down syndrome is the most common autosomal chromosomal abnormality. According to the classical interpretation, it is the result of meiotic nondisjunction. Its occurrence is more common in advanced maternal age. Despite intensive research, pathophysiology of this genetic disorder is not fully understood. According to recent studies, a different kind of mechanism may be found in the background of trisomy 21 than was previously considered. Based on the ovarian mosaicism model, the cause of trisomy 21 (or any common trisomy) is a segregation error of a chromosome in premeiotic mitosis...
July 2018: Orvosi Hetilap
Lin-Lin Hu, Xin Zhou, Hao-Lin Zhang, Lan-Lan Wu, Lian-Sheng Tang, Ling-Li Chen, Jin-Liang Duan
Podophyllotoxin is used as medical cream which is widely applied to genital warts and molluscum contagiosum. Although previous study showed that podophyllotoxin had minimal toxicity, it was forbidden to use during pregnancy since it might be toxic to the embryos. In present study we used mouse as the model and tried to examine whether podophyllotoxin exposure was toxic to oocyte maturation, which further affected embryo development. Our results showed that podophyllotoxin exposure inhibited mouse oocyte maturation, showing with the failure of polar body extrusion, and the inhibitory effects of podophyllotoxin on oocytes was dose-depended...
July 5, 2018: Scientific Reports
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