Exogenous progesterone during in vitro fertilization improves developmental competence of partially cumulus-denuded bovine oocytes.

The progesterone (P4) secreted by cumulus cells has gained attention for its role as a possible physiological inducer of sperm acrosome exocytosis. In mammals, it is generally accepted that fertilization rates of oocytes without cumulus are markedly low. This study assessed the integrity of capacitated bovine sperm acrosome when exposed to increasing concentrations of P4, and evaluated whether exogenous P4 during in vitro fertilization (IVF) increases the developmental competence of partially cumulus-denuded oocytes in serum-free conditions. After a 4-h capacitation induction, sperm were incubated with increasing concentrations of P4 (0, 0.1, 10 and 100 µM) and evaluated for viability, caspase activation and acrosome status at three different times (4, 5, and 22 h), including the capacitation induction period. Progesterone induced sperm acrosomal exocytosis without compromising sperm viability or activating sperm caspases. Sperm undergoing acrosome reaction exhibited three differential Concanavalin A patterns, corresponding to early, intermediate and late acrosomal exocytosis. The percentage of these patterns significantly increased over time, regardless of P4 concentration, except for those spermatozoa with late acrosomal exocytosis, which only showed an increase at 22 h of incubation. After incubation for 1 h with 100 µM P4, spermatozoa showing intermediate acrosomal exocytosis significantly increased. At 22 h of incubation, the pattern corresponding to early acrosomal exocytosis evidenced a dose-dependent increase. However, prematurely high levels of acrosome reaction induced by 100 µM P4 led to inefficient IVF outcomes (P < 0.05). Therefore, IVF trials with partially cumulus-denuded oocytes were carried out with lower P4 concentrations (0, 0.1, 1, 5, 10 µM). Cleavage rate significantly increased at 1 µM P4, which translated to increased total embryo production after 7 days of in vitro culture (P < 0.05). Significantly higher percentages of expanded blastocysts were observed at both 1 µM and 10 µM P4 as compared to the other experimental conditions. In conclusion, the different patterns of acrosomal exocytosis identified over time by incubation of live sperm with a fluorescent lectin revealed the existence of sperm subpopulations heterogeneous in their physiological states. Moreover, exogenous P4 at 1 µM during IVF improved the developmental competence of partially cumulus-denuded oocytes in serum-free conditions.

Towards an ideotype for food-fuel dual-purpose wheat in Argentina with focus on biogas production.

BACKGROUND: Wheat straw, one of the most abundant agricultural residues worldwide, can be used to produce biogas, which is considered one of the most efficiently produced renewable energies. Wheat grown with the dual-purpose of producing food and biogas should display simultaneously high grain and straw yields, low lodging susceptibility and high conversion efficiency of straw into biogas. The aims of this study were to determine the best food-fuel dual-purpose wheat candidates among 36 wheat genotypes-including French, CIMMYT and local (Criollo) germplasm-used in breeding programs in Argentina and to gain some insights into the relationships between key traits relevant for dual-purpose wheat genotypes. RESULTS: High variability in individual key traits for dual-purpose wheat ideotype has been found. Genotypes of French origin displayed the highest grain yield, and those of CIMMYT origin, the lowest straw yield. Genotypes of Criollo origin showed the highest lodging susceptibility, and French ones, the lowest. Straw yield was positively correlated with grain yield in all genotypes, and negatively correlated with plant height in genotypes of Criollo origin. Straw conversion into biogas was measured in terms of the biogas potential production and kinetic parameters Bmax (maximum specific biogas production) and k (first-order kinetic constant) were analyzed. All key traits were analyzed together by a principal component analysis. Baguette 31 and SNR Nogal, two genotypes of French origin, showed high grain yield, high-to-very high straw yield, low lodging susceptibility, and moderate-to-high Bmax and k. Buck Guapo and Buck Baqueano, two genotypes of Criollo origin, displayed good values for grain yield, straw yield and Bmax and k. However, their high lodging susceptibility precludes their production in shallow soils or high-input systems. Lastly, some old genotypes (e.g. Klein Atlas) harbored a good combination of all key traits and could prove valuable to be included in future breeding programs for dual-purpose wheat. CONCLUSIONS: While none of the genotypes excelled in every key trait, a few candidates showed potential for dual-purpose ideotype, particularly Baguette 31 and SNR Nogal. The challenge lays in gathering all attributes for food and 2G fuel in the same genotype.