Cover Story :
Based on the results obtained for the studies of in vitro development of cloned embryos, epigenetic modifications have been widely used for cloning farm animals. However, such studies remain few in canids because of the lack of optimal in vitro oocyte maturation, embryo culture, and superovulation system. Kim et al. investigated whether a histone deacetylase inhibitor used in dog to pig interspecies somatic cell nuclear transfer (iSCNT), which improves nuclear reprogramming, could be used in dog cloning (Kim et al.: Suberoylanilide hydroxamic acid during in vitro culture improves development of dog-pig interspecies cloned embryos but not dog cloned embryos. p. 277–282). Porcine oocytes supported reprogramming of nuclei from dog fibroblasts up to early developmental stage of iSCNT embryos, and treating the embryos with suberoylanilide hydroxamic acid (SAHA) increased their developmental competence. However, unfortunately, SAHA treatment for dog to pig iSCNT embryos was not sufficient to improve their in vivo development because three and one clones were successfully produced from the control and SAHA treated groups, respectively.
Cover Story :
Recently, the effects of macromolecular crowding on cultured cells have gathered increasing interest. Crowded culture medium prepared by the addition of polyvinylpyrrolidone (PVP; Mw 360,000) positively influences the viability of oocytes during in vitro growth. Mizumachi et al. found that crowding affects a wide range of factors, including oocyte viability, complex morphology, and intimate conjunction of oocytes with cumulus/granulosa cells across the zona pellucida (Mizumachi et al. Macromolecular crowded conditions strengthen contacts between mouse oocytes and companion granulosa cells during in vitro growth, pp. 153-160). Confocal laser scanning microscopy indicated a higher number of transzonal processes (TZPs) reaching the oocyte from cumulus cells in 2% PVP medium than in 0% PVP medium.
Cover Story :
Whether cumulus cells are required for the successful vitrification of mature oocytes in cattle is controversial. Ishii et al. re-evaluated the effects of the presence of multi-layered cumulus cells (MCCs) on the vitrification of mature bovine oocytes (Ishii et al., Embryogenesis of vitrified mature bovine oocytes is improved in the presence of multi-layered cumulus cells. pp. 95–99). In the presence of MCCs, there was no difference between the embryonic development of fresh and vitrified mature bovine oocytes. These results suggest that MCCs protect mature oocytes from freezing, and promote their survival and development after in vitro fertilization. Ishii et al. successfully produced calves using a small number of vitrified mature oocytes with MCCs collected from the ovaries of individual cows post-slaughter.
Monitoring Metabolic Health of Dairy Cattle in the Transition Period
Released: August 10, 2010 | Volume 56 Issue S Pages S29-S35
Relation of Prostaglandin F2α to a Function of Bovine Corpus Luteum in vitro
Released: May 15, 2008 | Volume 39 Issue 6 Pages j61-j66
Shizuo KAWAKAMI, Takaharu OHCHI, Masao SHINO, Hidemichi KOHMOTO
Mammary Growth and Regression -Regulation of Milk Synthesis-
Released: October 20, 2010 | Volume 42 Issue 6 Pages j143-j150
In vitro Production of Porcine Embryos: On the Developmental Competence
Released: October 20, 2010 | Volume 44 Issue 6 Pages j47-j52