Oocyte developmental competence and embryo quality: distinction and new perspectives

In vitro embryo production is the cornerstone of infertility treatment in human and is increasingly used in cattle to propagate high genetic merit animals. To increase its efficiency, many different approaches have been tested all of which stem from the concepts of oocyte quality and developmental competence. Presented here are recently reported findings and perspectives related to bovine oocyte biology and analysis of blastocyst quality that addresses these concepts from a different angle supporting the complex nature of the very dynamic developmental window that encompasses late oogenesis up to blastocyst development. It was recently reported that the atypical nature of the oocyte is supported by extensive nurturing from the surrounding cumulus cells in the form of large cargo transfer as well as transfer of phosphocreatine as an alternate means of generating ATP to fulfill the oocyte’s needs during the energy demanding process of maturation. It has been shown many times over that the determinants of early embryogenesis are embedded in the oocyte, however, transcriptome analysis dissociates embryonic yield from the concept of embryonic quality. Within the divergent gene expression, long non-coding RNAs represent a very functionally diverse class of transcripts that have yet been characterized. Taken together, it is clear that a clearer definition of both oocyte and embryonic quality are still needed to support the improvement of in vitro embryo production.

Oocyte developmental competence and embryo quality: distinction and new perspectives

In vitro embryo production is the cornerstone of infertility treatment in human and is increasingly used in cattle to propagate high genetic merit animals. To increase its efficiency, many different approaches have been tested all of which stem from the concepts of oocyte quality and developmental competence. Presented here are recently reported findings and perspectives related to bovine oocyte biology and analysis of blastocyst quality that addresses these concepts from a different angle supporting the complex nature of the very dynamic developmental window that encompasses late oogenesis up to blastocyst development. It was recently reported that the atypical nature of the oocyte is supported by extensive nurturing from the surrounding cumulus cells in the form of large cargo transfer as well as transfer of phosphocreatine as an alternate means of generating ATP to fulfill the oocytes needs during the energy demanding process of maturation. It has been shown many times over that the determinants of early embryogenesis are embedded in the oocyte, however, transcriptome analysis dissociates embryonic yield from the concept of embryonic quality. Within the divergent gene expression, long non-coding RNAs represent a very functionally diverse class of transcripts that have yet been characterized. Taken together, it is clear that a clearer definition of both oocyte and embryonic quality are still needed to support the improvement of in vitro embryo production.(AU)

Correlates of lipoprotein(a) levels in a biracial cohort of young girls: the NHLBI Growth and Health Study.

Elevated levels of lipoprotein(a) [Lp(a)] are associated with increased risk for coronary heart disease (CHD). However, racial differences in both Lp(a) levels and their associated CHD risk are observed, with African Americans having, on average, higher Lp(a) levels than US whites but not the expected increase in CHD risk. We determined Lp(a) levels and their correlates in a large cohort (n = 2379) of black and white girls, ages 9 to 10 years, at the baseline visit of a longitudinal study of obesity development, the National Heart, Lung, and Blood Institute Growth and Health Study. Lp(a) levels were available for 1269 girls. The median Lp(a) level in black girls was over 3-fold higher than that in white girls. Associations were examined between Lp(a) levels and low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol, apolipoprotein B, triglycerides, adiposity, pubertal maturation stage, body fat patterning (triceps/truncal skinfold ratio), and dietary fat (Keys' score). In black girls multiple regression analysis identified LDL-C (P <.001) and adiposity (P =. 08) as predictors of Lp(a) levels. In white girls only LDL-C (P =. 02) was associated with Lp(a). In conclusion, the level of Lp(a) was significantly higher in black girls. Our study also revealed a racial difference in correlates of Lp(a), such as LDL-C and adiposity. Whether this racial difference is due to an underlying biologic difference or is merely a reflection of a greater statistical power to detect a relationship with the level, which was 2.5-fold higher in black girls than in white girls, needs further investigation.