Progress in Stereoselective Construction of C-C Bonds Enabled by Aldolases and Hydroxynitrile Lyases.

The creation of C-C bonds is an effective strategy for constructing complex compounds from simple synthetic blocks. Although many methods have been developed for C-C bond construction, the stereoselective creation of new C-C bonds remains a challenge. The selectivities (enantioselectivity, regioselectivity, and chemoselectivity) of biocatalysts are higher than those of chemical catalysts, therefore biocatalysts are excellent candidates for use in stereoselective C-C bond formation. Here, we summarize progress made in the past 10 years in stereoselective C-C bond formation enabled by two classic types of enzyme, aldolases and hydroxynitrile lyases. The information in this review will enable the development of new routes to the stereoselective construction of C-C bonds.

Colony-stimulating factor 2 enhances the developmental competence of yak (Poephagus grunniens) preimplantation embryos by modulating the expression of heat shock protein 70 kDa 1A.

Colony-stimulating factor 2 (CSF2) is known to promote the development and survival of rodents and ruminants preimplantation embryos; however, the effect of CSF2 on yak embryos has not been reported. The objective of this study was to investigate the effects of CSF2 on the developmental competence of yak embryos cultured in vitro in modified synthetic oviduct fluid (mSOF) medium and on the expression pattern of heat shock protein 70 kDa 1A (HSPA1A). In each experiment, cumulus-oocyte complexes (COCs) were matured in vitro and fertilized with frozen-thawed semen. Zygotes were treated with varying concentrations of CSF2 (0, 10, 50, 100 ng/mL) until day 8 after fertilization. Embryo development was calculated as the percentage of oocytes that formed embryos at the 2-cell, 4-cell, 8-cell, 16-cell, morula and blastocyst stages. The total cell numbers (TCN) per blastocyst and their allocation to the inner cell mass (ICM) and trophectoderm (TE) lineages were determined using differential CDX2 staining. The expression of HSPA1A was examined by quantitative real-time PCR (qRT-PCR) and immunochemistry to determine the mRNA and protein levels. The results showed that treatment with 50 ng/mL CSF2 significantly (P < 0.05) increased the rate of blastocyst formation (19.01% versus 9.93%) and the TCN per blastocyst (96.94 versus 81.41) compared to the control group. However, no significant differences were observed in the other stages of development. qRT-PCR analysis confirmed that treatment with 50 ng/mL CSF2 significantly (P < 0.05) inhibited the expression of HSPA1A mRNA in blastocysts cultured in vitro relative to the control group, but there were no significant differences between the other treatment groups. Immunocytochemical analysis confirmed that HSPA1A protein accumulation was gradually reduced in yak blastocysts cultured in 0, 10, 100 or 50 ng/mL CSF2, however, no significant differences were observed between the 10 and 100 ng/mL treatments (P > 0.05). In conclusion, these findings demonstrate that CSF2 inhibits the expression of HSPA1A to facilitate yak blastocyst formation and increase cell numbers.

Cloning of HSP90, expression and localization of HSP70/90 in different tissues including lactating/non-lactating yak (Bos grunniens) breast tissue.

The aim of this study is to investigate the expression and localization of HSP70/90 in different tissues and explore the regulation effects of HSP70/90 at lactation period of female yaks. HSP90 mRNA was cloned from the heart samples of female yaks, Quantitative real-time (qRT-PCR), Western blotting (WB), immunohistochemistry and immunofluorescence assays were utilized to analyze the expressions of HSP70/90 mRNA and protein in different tissues. Sequence analysis showed that HSP90 is a conserved molecular chaperone of female yaks. The qRT-PCR, WB results showed that the expressions of HSP70/90 mRNA and protein were significantly different in different tissues, and 3-fold higher expression during the lactation period than the non-lactation period of breast tissue (P < 0.01). Immunohistochemistry and immunofluorescence assays results showed that HSP70/90 were located in the cardiac muscle cells, cerebellar medulla, theca cells lining at the reproductive system, and the mammary epithelia of the breasts. In addition, the expression level of HSP70 was higher than those of HSP90 in all examined tissues. Therefore, our results strongly suggest that the expression and localization of HSP70/90 could provide significant evidence to further research in tissue specific expression, and lactation function of female yaks.