Elevated Non-Esterified Fatty Acid Concentrations during Bovine Oocyte Maturation Compromise Early Embryo Physiology

Elevated concentrations of serum non-esterified fatty acids (NEFA), associated with maternal disorders such as obesity and type II diabetes, alter the ovarian follicular micro-environment and have been associated with subfertility arising from reduced oocyte developmental competence. We have asked whether elevated NEFA concentrations during oocyte maturation affect the development and physiology of zygotes formed from such oocytes, using the cow as a model. The zygotes were grown to blastocysts, which were evaluated for their quality in terms of cell number, apoptosis, expression of key genes, amino acid turnover and oxidative metabolism. Oocyte maturation under elevated NEFA concentrations resulted in blastocysts with significantly lower cell number, increased apoptotic cell ratio and altered mRNA abundance of DNMT3A, IGF2R and SLC2A1. In addition, the blastocysts displayed reduced oxygen, pyruvate and glucose consumption, up-regulated lactate consumption and higher amino acid metabolism. These data indicate that exposure of maturing oocytes to elevated NEFA concentrations has a negative impact on fertility not only through a reduction in oocyte developmental capacity but through compromised early embryo quality, viability and metabolism

Effects of temperature on germination and hyphal growth from ascospores of A-group and B-group Leptosphaeria maculans (phoma stem canker of oilseed rape)

Ascospores of both A-group and B-group Leptosphaeria maculans germinated at temperatures from 5-20degreesC on distilled water agar or detached oilseed rape leaves. After 2 h of incubation on water agar, some A-group ascospores had germinated at 10-20degreesC and some B-group ascospores had germinated at 5-20degreesC. The percentages of both A-group and B-group ascospores that had germinated after 24 h of incubation increased with increasing temperature from 5-20'C. The observed time (Vo(50)) which elapsed from inoculation until 50% of the spores had germinated was shorter for B-group than for A-group ascospores. Germ tube length increased with increasing temperature from 5-20degreesC for both ascospore groups. Germ tubes from B-group ascospores were longer than germ tubes from A-group ascospores at all temperatures tested, but the mean diameter of germ tubes from A-group ascospores (1.8 mum) was greater than that of those from B-group ascospores (1.2 mum) at 15degreesC and 20degreesC. The average number of germ tubes produced from A-group ascospores (3.8) was greater than that from B-group ascospores (3.1) after 24 h of incubation at 20degreesC, on both water agar and leaf surfaces. Germ tubes originated predominantly From interstitial cells or terminal cells of A-group or B-group ascospores, respectively, on both water agar and leaf surfaces. Hyphae from A-group ascospores grew tortuously with extensive branching, whilst those from B-group ascospores were predominantly long and straight with little branching, whether the ascospores were produced from oilseed rape debris or from crosses between single ascospore isolates, and whether ascospores were germinating on water agar or leaf surfaces.Peer reviewe