The review article by Uenoyama et al. describes the roles of hypothalamic kisspeptin in the central mechanism regulating puberty and subsequent reproductive functions in mammals. The schematic illustration shows a possible mechanism regulating the pubertal augmentation of Kiss1 expression in the arcuate nucleus (ARC) to trigger pulsatile GnRH/gonadotropin secretion in rodents. The authors suspect that estrogen strongly suppresses ARC Kiss1 expression during the prepubertal period via direct and indirect pathways and that the sensitivity to estrogen negative feedback action on ARC Kiss1 expression decreases during the pubertal transition. The resultant increase in secretion of kisspeptin would trigger GnRH/gonadotropin secretion at pubertal onset (Uenoyama et al. The role of kisspeptin in the mechanism underlying reproductive function in mammals. pp. 469–476).
Dry biobanking has many advantages over the current paradigm of storing cryopreserved cells under liquid nitrogen. During drying, however, the cells become damaged. The highly condensed spermatozoa DNA has been shown in many desiccation studies to generally maintain its integrity. Using ram freeze-dried epididymal spermatozoa as a model, Palazzese et al. were the first to evaluate both single- and double-strand DNA breaks (SSBs and DSBs, respectively), showing that drying causes minimal DSBs but extensive SSBs (Palazzese L et al., 2018. DNA fragmentation in epididymal freeze-dried ram spermatozoa impairs embryo development, pp. 393–400). Furthermore, the authors also demonstrated that spermatozoa capable of directing embryo development to the blastocyst stage in vitro originated from rams with the least DNA damage Overall, the impact of sperm DNA damage on embryonic development depends on a balance between the extent of sperm DNA fragmentation, fragmentation type, and the oocyte’s repair capacity.
Cover Story: Oog1, an oocyte-specific gene, encodes the protein belonging to the leucine-rich repeat (LRR) superfamily. LRR is a motif involved in protein-protein interactions. Complete knockout of Oog1 is challenging because five copies of the Oog1 gene are present on chromosomes 4 and 12. Honda et al. generated Oog1 RNA interference (RNAi)-transgenic mice to investigate the effects of Oog1 knockdown on gene expression in the oocytes (Honda et al. Oocyte-specific gene Oog1 suppresses the expression of spermatogenesis-specific genes in oocytes, pp. 297–301). The abundance of spermatogenesis-specific transcripts was elevated in the Oog1 knockdown ovaries. In addition, a few abnormal oocytes were observed in 6-month-old Oog1 knockdown mouse ovaries. These findings suggested that OOG1 suppresses the expression of spermatogenesis-specific genes in the oocytes and plays important roles during oogenesis.
Monitoring Metabolic Health of Dairy Cattle in the Transition Period
Released: August 10, 2010 | Volume 56 Issue S Pages S29-S35
Mammary Growth and Regression -Regulation of Milk Synthesis-
Released: October 20, 2010 | Volume 42 Issue 6 Pages j143-j150
Infectious Causes of Reproductive Disorders in Cattle
Released: August 10, 2010 | Volume 56 Issue S Pages S53-S60
Han Sang YOO
In vitro Production of Porcine Embryos: On the Developmental Competence
Released: October 20, 2010 | Volume 44 Issue 6 Pages j47-j52