Effect of roscovitine on developmental competence of small follicle-derived buffalo oocytes.

Background & objectives: The lower recovery of competent oocytes in buffalo species limits the commercialization of in vitro embryo production technology in field condition. In this context, pre-maturation of small follicle (SF)-derived oocytes with meiotic inhibition may be a promising alternative to obtain more number of competent oocytes. Thus, the present study was conducted with an objective to enhance the developmental potential of less competent SF-derived buffalo oocytes. Methods: All the visible follicles (used for aspiration) from buffalo ovaries were divided into two categories: large follicle (LF) (follicles having diameter ≥6 mm) and SF (follicles of diameter <6 mm). The competence of LF and SF oocytes was observed in terms of brilliant cresyl blue (BCB) staining, cleavage rate, blastocyst rate and relative gene expression of oocyte and blastocyst competence markers. Thereafter, less competent SF oocytes were treated with 0, 12.5, 25, 50 and 100 mM doses of roscovitine (cyclin-dependent kinase inhibitor) to enhance their developmental potential. Results: Based on parameters studied, LF oocytes were found to be more competent than SF oocytes. Pre-maturation incubation of SF oocytes with roscovitine reversibly arrested oocyte maturation for 24 h to ensure the proper maturation of less competent oocytes. A significantly higher number of BCB-positive oocytes were noted in roscovitine-treated group than SF group. Cleavage and blastocyst rates were also higher in roscovitine-treated group. The relative messenger RNA expression of oocyte (GDF9, BMP15, GREM1, EGFR, PTGS2 and HAS2) as well as blastocyst (INF-τ, GLUT1 and POU5F1) competence markers was significantly greater in roscovitine-treated group relative to SF group. Again, on comparison with LF group, these parameters depicted a lower value in the treatment group. Interpretation & conclusions: The findings of this study has revealed that pre-maturation incubation of SF-derived oocytes with 25 µM roscovitine can improve its developmental competence and thus can be utilized to get maximum number of competent oocytes for better commercialization of in vitro embryo production technology in buffalo.

Effect of supplementation of recombinant Regucalcin in extender on cryopreservation of spermatozoa of water buffalo (Bubalus bubalis).

Elevated intracellular calcium concentration and oxidative damage are two major factors contributing to the poor fertility of cryopreserved spermatozoa. Regucalcin (RGN), also known as Senescence marker protein-30 (SMP-30), is a calcium-binding protein with multiple roles that include calcium homeostasis, anti-oxidative, anti-apoptosis, and anti-proliferation. In Drosophila, RGN is reportedly a putative cold-tolerance gene and a cytoprotective role for RGN against intracellular calcium elevation and oxidative stress was reported in P19 cell lines. Given that RGN has anticapacitatory effect and abundant in the male reproductive tract, we hypothesized that it may play a cryoprotective role for spermatozoa. We investigated this by including RGN, at three different concentrations (20, 40, and 60 µg/ml), as a supplement for Tris-egg yolk-based semen extender. Post-thaw metrics of progressive motility, acrosome integrity, and zona pellucida binding of spermatozoa were evaluated for three ejaculates of three clinically normal, breeding Murrah buffaloes. A concentration of 40 µg/ml of recombinant RGN supplemented during sperm freezing resulted in significant increases in the post-thaw progressive motility of spermatozoa (50.6 ± 3.5% vs 40.6 ± 2.6%; p < 0.01), acrosome integrity (53.3 ± 7.4 vs 75.6 ± 6.8; p < 0.05), and zona pellucida binding (31.6 ± 14.0 vs 191.9 ± 12.3 bound spermatozoa; p < 0.01) compared to control conditions without RGN. Thus, ∼1 µM recombinant RGN, which retains the ability to bind calcium, has a cryoprotective effect for buffalo spermatozoa in extender.

Leptin supplementation in vitro improved developmental competence of buffalo oocytes and embryos.

The aim of the present study was to determine potential role of leptin on in vitro developmental competence of buffalo oocytes and embryos. Slaughterhouse derived culture grade buffalo cumulus oocyte complexes (COCs) were matured in vitro (IVM) with leptin (10 ng/ml) or without leptin (control). In each experiment, a pool of matured COCs was used for further in vitro embryo production and another pool of COCs was used for cumulus cells and mature oocytes isolation to study the relative mRNA expression of developmentally important genes. Presumptive zygotes were cultured in embryo culture (IVC) media supplemented with leptin (10 ng/ml) or without leptin (control). Cleavage rate was higher (p < 0.05) when leptin was supplemented during IVM + IVC, both, as compared to other groups. Higher cleavage rate was observed in leptin-treated groups, though it was non-significant. Blastocyst rate was higher (p < 0.05) in all the leptin treated groups. The relative mRNA expression of LEPR (Ob-Rb), HAS2 and EGFR was significantly (p < 0.05) up-regulated and the expression of CASPASE3 was down-regulated in cumulus cells of leptin-treated groups. The expression of GDF9, BMP15, GLUT1, LEPR and CASPASE3 transcripts in leptin and non-treated oocytes did not differ. The relative mRNA expression of POU5F1and LEPR transcripts in blastocysts was higher (p < 0.05) in leptin-treated groups; the change in expression of GLUT1, INF-τ and CASPASE3 transcripts was not significant (p > 0.05). Thus, it is concluded that leptin promotes developmental competence of bubaline oocytes by modulating cumulus enabling factors and genes regulating pluripotentcy in the blastocysts.

Impact of oocyte-secreted factors on its developmental competence in buffalo.

Oocyte-secreted factors (OSFs) play an important role in the acquisition of oocyte developmental competence through bidirectional cross-talk between oocyte and cumulus cells via gap junctions. Thus, the present study was designed to investigate the effect of two OSFs, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), on the developmental competence of buffalo oocytes derived from two different follicle sizes. Cumulus-oocyte complexes (COCs) from large follicles (LF, >6 mm) or small follicles (SF, 0.05) between DOs and combination groups. Relative mRNA analysis revealed significantly higher (P > 0.05) expression of the cumulus cell marker genes EGFR, HAS2, and CD44 in LF-derived than SF-derived oocyte; the expression of these markers was significantly higher (P > 0.05) in DOs and combination groups, irrespective of the follicle size. These results suggested that LF-derived oocytes have a higher developmental competence than SF-derived oocytes and that supplementation of GDF9 and BMP15 modulates the developmental competence of buffalo oocytes by increasing the relative abundance of cumulus-enabling factors and thereby increasing cleavage and the quality of blastocyst production.

Expression and secretory profile of buffalo fetal fibroblasts and Wharton's jelly feeder layers.

The present study examined the comparative expression and secretory profile of vital signaling molecules in buffalo fetal fibroblasts (BFF) and Wharton's jelly (BWJ) feeder layers at different passages. Both feeder layers were expanded up to 8th passage. Signaling molecules viz. bone morphogenetic protein 4 (BMP4), fibroblast growth factor 2 (FGF2), leukemia inhibitory factor (LIF) and transforming growth factor beta 1 (TGFB1) and pluripotency-associated transcriptional factors (POU5F1, SOX2, NANOG, KLF4, MYC and FOXD3) were immunolocalized in the both feeder types. A clear variation in the expression pattern of key signaling molecules with passaging was registered in both feeders compared to primary culture (0 passage). The conditioned media (CM) was collected from different passages (2, 4, 6, 8) of both the feeder layers and was quantified using enzyme-linked immunosorbent assay (ELISA). Concomitant to expression profile, protein quantification also revealed differences in the concentration of signaling molecules at different time points. Conjointly, expression and secretory profile revealed that 2nd passage of BFF and 6th passage of BWJ exhibit optimal levels of key signaling molecules thus may be selected as best passages for embryonic stem cells (ESCs) propagation. Further, the effect of mitomycin-C (MMC) treatment on the expression profile of signaling molecules in the selected passages of BFF and BWJ revealed that MMC modulates the expression profile of these molecules. In conclusion, the results indicate that feeder layers vary in expression and secretory pattern of vital signaling molecules with passaging. Based on these findings, the appropriate feeder passages may be selected for the quality propagation of buffalo ESCs.

GREM1, EGFR, and HAS2; the oocyte competence markers for improved buffalo embryo production in vitro.

Selection of competent oocytes is crucial for successful in vitro embryo production and correlating expression profile of oocyte competence markers in cumulus cells with oocyte quality is an important preamble. In the present study, expression profile of oocyte competence markers (GREM1, EGFR, HAS2, and TNFAIP6) was correlated through brilliant cresyl blue (BCB) staining and subsequently with in vitro embryo production. Excellent to good quality buffalo, cumulus oocyte complexes (COCs) were stained with BCB (26 µM) and based on the blue coloration of cytoplasm COCs were divided in two groups as BCB(+ve) and BCB(-ve). Mean percentage of BCB(+ve) oocytes was significantly higher (P < 0.05) than BCB(-ve) oocytes (56.79 ± 1.22 vs. 43.20 ± 1.22), the mean oocyte diameter was also significantly larger (P < 0.05) for the BCB(+ve) group than that of BCB(-ve) group (145.7 ± 1.8 µm vs. 132.7 ± 1.9 µm). The cleavage rate (%), blastocyst rate (%), and total cell number was significantly (P < 0.05) higher in BCB(+ve) than BCB(-ve) group (71.15 ± 2.17 vs. 52.89 ± 2.65; 31.58 ± 1.11 vs. 7.73 ± 0.97, and 93.14 ± 2.42 vs. 71.42 ± 2.09, respectively). Relative mRNA expression of marker genes in cumulus cells increased significantly (P < 0.05) after maturation viz. GREM1 (10.13 folds), EGFR (9.04 folds), HAS2 (27.91 folds), and TNFAIP6 (64.81 folds). Brilliant cresyl blue positive oocytes showed significantly higher (P < 0.05) expression of GREM1, EGFR, and HAS2 transcripts than BCB(-ve) oocytes, however, no significant change in the expression of TNFAIP6 gene was observed. It is concluded from the study that GREM1, EGFR, and HAS2 could be used as molecular markers of oocyte competence for an improved buffalo embryo production in vitro.

Stem Cell Conditioned Media Contains Important Growth Factors and Improves In Vitro Buffalo Embryo Production.

The present study was designed to investigate the effect of MSCs-conditioned media (CM) on quality buffalo embryo production in vitro. MSCs were harvested from Wharton's jelly of 2-3 month old fetus and MSCs CM was collected. Immunocytochemistry and western blot assay revealed that MSCs secrete several important growth factors viz. FGF-2, IGF-1, LIF, TGF-ß, and VEGF. Slaughterhouse derived culture grade cumulus oocyte complexes (COCs) were matured and fertilized in vitro. Presumptive zygotes were divided in four groups and cultured in vitro in respective media viz. group I (100% mSOF), Group II (100% Knockout Media DMEM+SR), Group III (50% CM + 50% mSOF), and group IV (100% CM). It was found that though the cleavage rate did not changed significantly (p < 0.05), but blastocyst rate was increased significantly (p < 0.05) in Group III and IV (24.24 ± 1.34 and 23.29 ± 1.25, respectively) compared to group I and II (16.04 ± 1.46 and 17.72 ± 0.94, respectively). Similarly, TCN was significantly (p < 0.05) higher in 50% CM and 100% CM replacement group (93.33 ± 1.91 and 92.13 ± 1.04, respectively) than the other two groups. It can be concluded from the study that MSCs secrete several important growth factors and MSCs-CM can be effectively used for enhancement of quality buffalo embryo production in vitro.