• BMB Reports
• /
• 제43권6호
• /
• pp.389-399
• /
• 2010

Fertilization is a complex process comprised of numerous steps. During fertilization, two highly specialized and differentiated cells (sperm and egg) fuse and subsequently trigger the development of an embryo from a quiescent, arrested oocyte. Molecular interactions between the sperm and egg are necessary for regulating the developmental potential of an oocyte, and precise coordination and regulation of gene expression and protein function are critical for proper embryonic development. The nematode Caenorhabditis elegans has emerged as a valuable model system for identifying genes involved in fertilization and the oocyte-to-embryo transition as well as for understanding the molecular mechanisms that govern these processes. In this review, we will address current knowledge of the molecular underpinnings of gamete interactions during fertilization and the oocyte-to-embryo transition in C. elegans. We will also compare our knowledge of these processes in C. elegans to what is known about similar processes in mammalian, specifically mouse, model systems.

• 한국발생생물학회지:발생과생식
• /
• 제23권1호
• /
• pp.1-9
• /
• 2019

The ability of oocytes to undergo normal fertilization and embryo development is acquired during oocyte maturation which is transition from the germinal vesicle stage (GV), germinal vesicle breakdown (GVBD) to metaphase of meiosis II (MII). Part of this process includes redistribution of inositol 1, 4, 5-triphosphate receptor (IP3R), a predominant $Ca^{2+}$ channel on the endoplasmic reticulum membrane. Type 1 IP3R (IP3R1) is expressed in mouse oocytes dominantly. At GV stage, IP3R1 are arranged as a network throughout the cytoplasm with minute accumulation around the nucleus. At MII stage, IP3R1 diffuses to the entire cytoplasm in a more reticular manner, and obvious clusters of IP3R1 are observed at the cortex of the egg. This structural reorganization provides acquisition of $[Ca^{2+}]_i$ oscillatory activity during fertilization. In this review, general properties of IP3R1 in somatic cells and mammalian oocyte are introduced.

• 한국발생생물학회지:발생과생식
• /
• 제18권3호
• /
• pp.153-160
• /
• 2014

Adaptive development of early stage embryo is well established and recently it is explored that the mammalian embryos also have adaptive ability to the stressful environment. However, the mechanisms are largely unknown. In this study, to evaluate the possible role of aquaporin in early embryo developmental adaptation, the expression of aquaporin (AQP) 5 gene which is detected during early development were examined by the environmental condition. To compare expression patterns between in vivo and in vitro, we conducted quantitative RT-PCR and analyzed localization of the AQP5 by whole mount immunofluorescence. At in vivo condition, Aqp5 expressed in oocyte and in all the stages of preimplantation embryo. It showed peak at 2-cell stage and decreased continuously until morula stage. At in vitro condition, Aqp5 expression pattern was similar with in vivo embryos. It expressed both at embryonic genome activation phase and second mid-preimplantation gene activation phase, but the fold changes were modified between in vivo embryos and in vitro embryos. During in vivo development, AQP5 was mainly localized in apical membrane of blastomeres of 4-cell and 8-cell stage embryos, and then it was localized in cytoplasm. However, the main localization area of AQP5 was dramatically shifted after 8-cell stage from cytoplasm to nucleus by in vitro development. Those results explore the modification of Aqp5 expression levels and location of its final products by in vitro culture. It suggests that expression of Aqp5 and the roles of AQP5 in homeostasis can be modulated by in vitro culture, and that early stage embryos can develop successfully by themselves adapting to their condition through modulation of the specific gene expression and localization.

• 한국수정란이식학회지
• /
• 제18권3호
• /
• pp.263-267
• /
• 2003

본 연구에서 소 미성숙 난자의 성숙 배양 시 세포주기 억제제인 cycloheximide, 6-DMAP, rosco-vitine를 첨가하였을 때 난자의 감수분열이 억제제비 첨가난자에 비해 높은 비율로 germinal vesicle 기에서 정지된 것이 관찰되었다. 또한 cyclohexi-mide, 6-DMAP, roscovitine을 배지에서 제거한 후 다시 추가적인 체외 성숙 배양을 실시하여 ger-minal vesicle기에 정지된 세포주기의 진행이 재개되어 난자의 감수분열 완료 및 성숙이 세포주기억제제 비 첨가난자와 거의 동등하게 나타난 것을 확인할 수 있었다. 본 연구를 통하여 cyclo-heximide, 6-DMAP, roscovitine의 소 미성숙 난자의 세포주기 조절작용이 가역적임을 알 수 있었으며 난자의 세포 주기 동기화에 이용할 수 있을 것으로 사료된다.

• 한국수정란이식학회:학술대회논문집
• /
• 한국수정란이식학회 2002년도 국제심포지엄
• /
• pp.98-98
• /
• 2002

Recruitment of primordial follicles(PMF) is crucial for female fertility. however, factors and mechanisms that regulate this process is poorly understood. The present study was conducted to obtain an inclusive view of the gene expression and to identify novel factors and their pathways of regulating PMF arrest and/or growth initiation. Ovaries from one-day neonatal(consists of oocyte and PMF) and five-day old(consists of PMF and primary follicles, PRIF) mice were collected, either total RNA or mRNA was isolated, and suppression subtractive hybridization(SSH) was used to isolate and clone genes that differentially expressed in day 1 and day 5 ovaries. Confirmation that some of these genes are differentially expressed in PMF and/or in PRIF was accomplished by using laser captured microdissection(LCM), RT-PCR. in situ hybridization(ISH) and/or immunohistochemistry(IHC). In toto, 357 clones were sequenced and analyzed by BLAST and RIKEN program. Sequences of 330 clones significantly matched database entries while 27 clones were novel. Forty-two and 47 different genes were identified as differentially expressed in day 1 and day 5 ovaries, respectively, while 7 genes were expressed in both stages of ovaries. Day 5-subtracted library included several genes known as markers far growing follicles, such as ZP2, MATER, and fetuin. Among the genes with assigned functions, 23.8% was associated with cell cycle/apoptosis regulation, 7.1% with cellular structure, 11.9% with metabolism, 26.2% with signal transduction, and 31.0% with gene/protein expression in day 1; while 10.6%, 17.0%, 23.5%, 25.5%, and 23.4% in day 5, respectively. Genes such as GDF-8, Lats2, Septin2, and Weel were the highly expressed genes in PMF, while HSP84, Laminin2, MATER, MTi7, PTP, and Wrn were highly expressed genes in PRIF. We have successfully discovered list of genes expressed in day 1 and day 5 ovaries and confirmed that some of them are differentially expressed in PMF and/or PRIF. Gene expression profile from the present study would provide insight for the future study on the mechanism(s) involved in primordial-primary follicular transition. This work was Supported by Korean Health 21 RND Project, Ministry of Health and Welfare, Korea (01-PJ10-PG6-01GN13-0002).

• Reproductive and Developmental Biology
• /
• 제36권4호
• /
• pp.237-241
• /
• 2012

Embryonic genome activation (EGA) is the first major transition that occurs after fertilization, and entails a dramatic reprogramming of gene expression that is essential for continued development. Although it has been suggested that EGA in porcine embryos starts at the four-cell stage, recent evidence indicates that EGA may commence even earlier; however, the molecular details of EGA remain incompletely understood. The RNA polymerase II of eukaryotes transcribes mRNAs and most small nuclear RNAs. The largest subunit of RNA polymerase II can become phosphorylated in the C-terminal domain. The unphosphorylated form of the RNA polymerase II largest subunit C-terminal domain (IIa) plays a role in initiation of transcription, and the phosphorylated form (IIo) is required for transcriptional elongation and mRNA splicing. In the present study, we explored the nuclear translocation, nuclear localization, and phosphorylation dynamics of the RNA polymerase II C-terminal domain in immature pig oocytes, mature oocytes, two-, four-, and eight-cell embryos, and the morula and blastocyst. To this end, we used antibodies specific for the IIa and IIo forms of RNA polymerase II to stain the proteins. Unphosphorylated RNA polymerase II stained strongly in the nuclei of germinal vesicle oocytes, whereas the phosphorylated form of the enzyme was confined to the chromatin of prophase I oocytes. After fertilization, both unphosphorylated and phosphorylated RNA polymerase II began to accumulate in the nuclei of early stage one-cell embryos, and this pattern was maintained through to the blastocyst stage. The results suggest that both porcine oocytes and early embryos are transcriptionally competent, and that transcription of embryonic genes during the first three cell cycles parallels expression of phosphorylated RNA polymerase II.