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D R Armant

Publications and source records attributed to D R Armant.

60 records · Page 4Linked to original sources
PubMed1980

Cell surface localization of 5'AMP nucleotidase in prestalk cells of Dictyostelium discoideum.

5'AMP nucleotidase activity was localized by electron microscopy in Dictyostelium discoideum during cell differentiation. In addition, the activity was assayed by micro enzymic methods in sections dissected from specific cellular regions of lyophilized individuals. The results of the 2 procedures were in agreement, demonstrating that at the culmination stage of development the activity is strikingly localized in the prestalk cells adjacent to the prespore region. The cytochemically stained reaction product appeared only along the plasma membrane of the cells. As prestalk cells migrate into the stalk sheath and undergo differentiation, the activity is rapidly lost. Examination of stained cells at high magnification revealed the product accumulation to be primarily at the cell surface, suggesting that the enzyme functions extracellularly. Occasionally, cells having the morphological appearance of prestalk cells were found within the prespore region. These cells demonstrated 5'AMP nucleotidase activity at their plasma membrane in sharp contrast with neighbouring prespore cells. The strategic localization of 5'AMP nucleotidase may reflect a mechanism for establishing and maintaining regulatory levels of extracellular 5'AMP and/or adenosine during pattern formation in this model system.

5'-Nucleotidase↗
PubMedDate not supplied

Stimulation of ejaculated domestic cat sperm motility with caffeine, pentoxifylline, and 2'-deoxyadenosine.

Sperm motility patterns of cryopreserved domestic cat ejaculates treated at 37 degrees C with 1 mM caffeine, pentoxifylline, or 2'-deoxyadenosine were analyzed using computer-assisted semen analysis (CASA). The percent motility (MOT), curvilinear velocity (VLC), straight-line velocity (VSL), linearity (LIN), and amplitude of lateral head displacement (ALH) were measured for each group following 15 min of treatment. Motility indices were examined during a 6-h treatment period to determine the effect of each chemical on sperm longevity. Caffeine, pentoxifylline, and 2'-deoxyadenosine each increased (p > .05) the MOT and VCL of the ejaculates compared to the controls. The longevity of the treated and control samples were not significantly different throughout the incubation period. These results, similar to previous findings with cryopreserved epididymal cat sperm, demonstrate that motility stimulants can significantly elevate the MOT and VCL of cryopreserved ejaculated cat sperm without having deleterious effects on longevity.

Animals↗
PubMedDate not supplied

Stimulation of cryopreserved epididymal spermatozoa of the domestic cat using the motility stimulants caffeine, pentoxifylline, and 2'-deoxyadenosine.

We have investigated the effects of caffeine, pentoxifylline, and 2'-deoxyadenosine on the motion characteristics and longevity of domestic cat spermatozoa. Freshly collected or cryopreserved domestic cat epididymal sperm were incubated with 0.01-20 mM caffeine, pentoxifylline, or 2'-deoxyadenosine for 15 minutes at 23 degrees C. The percent motility (MOT), curvilinear velocity (VCL), linearity (LIN), straight line velocity (VSL), and amplitude of lateral head displacement (ALH) were determined for each group using computer-assisted semen analysis. Freshly collected domestic cat sperm exhibited a strong forward progressive movement, and treatment with caffeine, pentoxifylline, or 2'-deoxyadenosine did not consistently alter sperm motion. Following cryopreservation, spermatozoa exhibited decreased (P < 0.05) MOT, VCL, VSL, and ALH. Caffeine and pentoxifylline increased (P < 0.05) the MOT, VSL, VCL, and ALH of cryopreserved sperm at 0.01-20 mM, in a dose-dependent manner. 2'-Deoxyadenosine also increased (P < 0.05) both VSL and VCL at 1.0 mM, and MOT, VSL, VCL, and ALH at 10 mM. All treatments shifted the percentage of nonhyperactive sperm to either a transitional or hyperactivated state. The motility indices of cryopreserved samples were examined during a 6-hour incubation to assess the effects of caffeine, pentoxifylline, and 2'-deoxyadenosine on sperm longevity. Compared to untreated control samples, the longevity of stimulated cryopreserved sperm was not reduced. These results indicate that motility stimulants may prove useful for enhancing the fertility of cryopreserved cat sperm by increasing their motility and producing hyperactivated motion.

Animals↗
PubMedDate not supplied

Computer-assisted semen analysis (CASA) of epididymal sperm from the domestic cat.

Motion characteristics of epididymal sperm from domestic cats exhibiting a high (> 60%; normozoospermic; n = 21) or low (< 40%; teratozoospermic; n = 6) occurrence of structurally normal spermatozoa were correlated with morphology (MOR) using computer-assisted semen analysis (CASA). Mean values and standard errors for percent motility (MOT), curvilinear velocity (VCL), linearity (LIN), straight line velocity (VSL), and amplitude of lateral head displacement (ALH) were recorded for 3 hours. Average values for percent normal spermatozoa, MOT, VCL, VSL, and ALH were higher (P < 0.01) in samples from normozoospermic cats than from teratozoospermic cats at 0 hours, and there was no difference in motion parameters over the 3-hour incubation period in either group. Strong correlations (P < 0.01) existed between MOR and VCL, VSL, ALH, or MOT, but not LIN, upon regression analysis. We conclude that (1) motion parameters of domestic cat sperm are significantly correlated with morphology and (2) abnormal motion parameters associated with low fertility potential in other species are prevalent in samples from teratozoospermic cats. The correlation between morphology and altered sperm movement found in this study suggests that motion analysis of spermatozoa by CASA may be useful in evaluating fertilization potential in felids.

Animals↗