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.
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.
In vitro Production of Porcine Embryos: On the Developmental Competence
Released: October 20, 2010 | Volume 44 Issue 6 Pages j47-j52
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
Luteal Function and Estrous Cycles in Mammals
Released: October 20, 2010 | Volume 44 Issue 6 Pages j91-j97
JunYou LI, Maho ISHIDA, Masugi NISHIHARA, Toru SAWASAKI, Michio TAKAHASHI