Zinc stabilizes somatic cell membranes and DNA, inhibits respiration, is present in high concentrations in the male reproductive tract, and may stabilize sperm during storage and ejaculation. Zinc removal from sperm may be necessary to prepare sperm for fertilization (capacitation). Incubation with Zn2+ chelators, e.g., D-penicillamine, can capacitate hamster sperm (Andrews and Bavister, Gamete Res 1989; 23:159-70). In the present study, the Zn(2+)-specific fluorochrome N-(6-methoxy-8-quinolyl)-p-toluenesulfonamide (TSQ) and the vital stain propidium iodide were used to assess the zinc content of live hamster sperm with flow cytometry before and after capacitation. Capacitation was monitored with a salt-stored zona pellucida penetration assay or the occurrence of spontaneous or induced (with lysophosphatidylcholine) acrosome reactions. The effect of added zinc on sperm capacitation was also evaluated. Image Analysis was used to determine the subcellular location of zinc (TSQ fluorescence) and atomic absorption to determine whether the total zinc content of sperm changes during capacitation. Sperm incubated under non-capacitating conditions had high TSQ fluorescence and could not penetrate zonae pellucidae. Sperm incubated under capacitating conditions (plus BSA or D-penicillamine) were zinc-depleted (low fluorescence) and penetrated 90% or 78% of zonae, respectively. Image analysis showed a significant reduction in zinc in the acrosomal region during capacitation with BSA, but this did not correlate with the occurrence of spontaneous acrosome reactions. The atomic absorption data showed that the total zinc content of sperm was reduced by 44% or 40% when sperm were incubated under capacitating conditions (BSA or D-penicillamine, respectively). Zona pellucida penetration was completely inhibited when zinc was present throughout the capacitation period but not when it was added at the end of incubation. These data indicate that removal of zinc from hamster sperm is correlated with capacitation and may play a key regulatory role in this process.
This paper reports findings from an AHRC-funded project into the use of more than one language in research projects. Using 35 seminar presentations and 25 researcher profiles, we investigated how researchers from differing disciplines became aware of the possibilities, complexities, and emerging practices of researching where more than one language is used: for example, in initial research design, literature reviews, consent procedures, data generation and analysis, and reporting. Our analysis also revealed some of the challenges that researchers face regarding institutional policies, language choices, interpretation and translation practices, and the language politics of representation and dissemination. Based on this analysis, we argue that researchers need to account for the research spaces and the relationships these spaces engender, and recognise developing researcher awareness when researching multilingually.
The ability of domestic cat or leopard cat spermatozoa to penetrate zonae pellucidae (ZP) of salt-stored, domestic cat oocytes was examined as an assay for sperm capacitation. Ovarian oocytes were recovered after ovariectomy and matured in vitro for 18-36 h. Following removal of cumulus cells, the oocytes were used fresh, or stored (4°C, 0.5-24 weeks) in a HEPES-buffered hypertonic salt solution. Electroejaculated, washed sperm (2-4 X 10^ sperm/ml) were preincubated for 1.0 h (38°C, 5% CO2 in air) and then co-incubated (2 x 10^ sperm/mlj with fresh or stored oocytes for 6.0 h. Gametes were incubated in a protein-free, modified Tyrode's solution (TLP-PVA) or In the same medium containing 4.0 mg/ml bovine serum albumin (BSA; TALP-PVA). Treatments were compared for percentage ZP penetration (defined as sperm heads reaching more than halfway through the ZP) as an index of sperm capacitation. In both the domestic cat and leopard cat, there was no difference (P > 0.05) in sperm penetration of fresh ZP (domestic cat, 42.5 ± 5.4%-leopard cat, 38.6 ± 2.8%) or stored ZP (domestic cat, 32.4 ± 4.2%; leopard cat, 27.6 ± 2.3%). Sperm incubated in protein-free medium (TLP-PVA) were less capable (P<0.05) of ZP penetration (domestic cat, 14.6 ± 5.9%; leopard cat, 7.9 ± 3.0%) than sperm incubated in medium TALP-PVA containing BSA (domestic cat, 60.3 ± 5.9%; leopard cat, 58.4 ± 3.0%). These data indicate that (1) albumin facilitates capacitation and ZP penetrating ability of cat spermatozoa; (2) domestic cat ZP appear to lack a block to heterospecific penetration by "foreign" (leopard cat) sperm; and (3) penetration of stored domestic cat ZP can be used as an index of sperm capacitation in the domestic cat and the leopard cat.
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