Robert W. Atherton

Arginine uptake by rabbit spermatozoa

Abstract The transport of l -arginine by rabbit spermatozoa was found to proceed by saturable, chemically specific mechanisms. Kinetic analysis of initial rates of transport at substrate concentrations from 1.0 μ m to 1.0 μ m indicate the presence of two saturable transport components. A low-affinity component has an apparent K m of 0.64 μ m and an apparent V of 43.4 nmol/10 8 cells/30 s. A second, high-affinity component has an apparent K m of 4.0 μ m and an apparent V of 425 pmol/10 8 cells/30 s. Rabbit spermatozoa actively transported l -arginine in a range of pH values from 6.5 to 10.5 with a pH optimum for the low-affinity component of 7.2–7.6 and a pH optimum for the high-affinity component of 7.8–8.0. Inhibitor studies indicate that the energization for transport may be dependent on ATP rather than on a pH gradient or transmembrane potential. Competition experiments with arginine analogs and amino acids suggest that the high- and low-affinity components may recognize the terminal guanidino group.

The effect of the breeding season, cryopreservation and physiological extender on selected sperm and semen parameters of four ferret species: implications for captive breeding in the endangered black-footed ferret

In the present investigation, comparative baseline information on selected sperm characteristics of ejaculate spermatozoa of the domestic (Mustela putorius furo), fitch (Mustela sp.) and black-footed ferrets (Mustela nigripes) and the Siberian polecat (Mustela eversmanni) are presented. The main emphasis was to establish differences and similarities among these species in relation to semen and sperm quality during the breeding season, in cryopreservation success and in supporting sperm motility in different extenders or physiological media. The results confirm that most sperm morphology abnormalities were evident during the beginning of the breeding cycle in all four species. No significant interspecies differences were apparent in the sperm attributes examined, for all sampling months during the breeding season. Moreover, all species exhibited comparable patterns of reproductive seasonality. Cryopreservation suppressed sperm characteristics equally in all species studied. Ejaculate spermatozoa of closely related ferret species shared many similar motion characteristics using computer-aided sperm motility analysis. These results suggest that the basic sperm physiology of the ferret species under examination is very similar. Disparate to the interspecies comparisons, there were significant differences for most sperm motion parameters when spermatozoa of any of the ferrets were compared in different extenders. Assisted reproductive technologies developed for use in domestic ferret, fitch ferret or Siberian polecat may be successfully applied to captive breeding of the black-footed ferret using semen during any of the functional breeding months.

A METHOD FOR THE FRACTIONATION AND PURIFICATION OF SEA URCHIN SPERM

Procedures for fractionation and purification of sea urchin sperm subunits were studied. Fragmentation of cells was observed rather than fractionation of cell subunits when classic sonication or homogenization techniques were used. Calcium shock in alcohol solution which successfully removes Protozoa cilia was not effective in removing sperm flagella. Alcohol was found to induce cohesion among whole sperm rendering separation of isolated subunits by centrifugation impossible. Calcium shock without alcohol in the medium was not effective in achieving dissociation of sperm subunits.