M A de las Heras

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The efficacy of different vitrification solutions to cryopreserve in vitro produced bovine blastocysts was evaluated based upon in vitro development of embryos in culture and on in vivo development of embryos transferred into recipients. In the first experiment, ethylene glycol + glycerol (Eg + Gly) + different sucrose concentrations were evaluated. There(More)
We have evaluated the capacitating effect of gamma-aminobutyric acid (GABA) in ram spermatozoa in vitro, in a chemically defined medium, by means of the chlortetracycline (CTC) binding assay. Semen from adult Australian Merino rams was collected in an artificial vagina; spermatozoa were washed once in modified Biggers, Whitten, and Wittingham medium(More)
We have analyzed, by immunofluorescence, the localization of actin in ram spermatozoa, its colocalization with the actin-binding protein, gelsolin, and the effect of freeze/thawing, in vitro capacitation, and induced acrosomal exocytosis on its distribution. The monoclonal anti-actin and anti-gelsolin antibodies used recognized single bands at 43,000 and(More)
This report shows the results of a large-scale laparoscopic intrauterine insemination program on a flock of Australian Merino sheep in Argentine Patagonia. The study was carried out on a total of 1824 ewes (3-to-7-yr-old) and 480 ewe hoggets (19-20 months old) on 2 farms in the southeastern region of Santa Cruz Province, in April and May 1996. The animals,(More)
We studied the relationship between motility and membrane damage, as assessed by fluorescent staining, in fresh and in frozen-thawed ram spermatozoa. Semen from Merino rams was incubated with 6-carboxyfluorescein diacetate and propidium iodide. In both fresh and frozen-thawed samples, the percentage of intact spermatozoa was lower than the motility rate,(More)
We have described the different patterns of chlortetracycline (CTC) binding to ram spermatozoa, immediately after ejaculation and upon in vitro capacitation and calcium ionophore-induced acrosomal exocytosis. Four different forms of CTC distribution were found. Form I showed an even distribution of fluorescence over the entire head, with a brighter band in(More)
We investigated whether storage of pure ram semen at room temperature would facilitate the sperm capacitation process, as assessed by means of the chlortetracycline method. Objective motility, membrane integrity and ability of spermatozoa to undergo acrosome reaction induced by A23187 for 15 min were simultaneously evaluated to gain further insight into(More)
Daily variations in melatonin content and 2-[125I]melatonin specific binding in retinas of golden hamsters were studied. Both parameters showed significant variations throughout the 24 h period. Maximal specific binding was observed at 24.00 h, while melatonin content peaked at 04.00 h. Saturation studies performed at 12.00 and 24.00 h indicated that the(More)
Ornithine decarboxylase (ODC) activity was measured in epididymides of 45-day-old rats. Higher ODC activity was detected in the corpus and cauda than in the caput epididymidis. Bilateral castration for 7 days caused epididymal ODC to fall to undetectable values, whereas testosterone restored activity to normal values. The effect of the androgen was(More)
We have measured sperm-bound amidase activity in fresh, cooled and frozen/thawed ram spermatozoa, in order to study if freezing and thawing led to some degree of acrosome damage of motile/viable spermatozoa not detected by optical methods. This assay was based on the fact that membrane damage would result in an increased access of the enzyme substrate to(More)