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Summary.

Anionic and cationic proteins were isolated from cervical mucus obtained from the cow during oestrus. The anionic proteins showed no antimicrobial activity whereas the cationic proteins inhibited the growth of Staphylococcus aureus S305 and Brucella abortus S19. Polyacrylamide gel electrophoresis, immunoelectrophoresis and isoelectric focusing experiments revealed the heterogeneous nature of the cervical mucus proteins. At pH 3·0, four main cationic fractions could be resolved by disc acrylamide electrophoresis. By electrophoresis in agarose at pH 8·6, aggregation occurred, with the exception of a more basic fraction which migrated towards the cathode. Lysozyme was absent from the isolated soluble proteins of cervical mucus, but serum albumin, and β- and γ-globulins were detected. Antimicrobial proteins in cervical mucus may provide an initial line of defence for the uterus against invading pathogens.

Summary.

The isoelectric points of washed spermatozoa from intact boars and from boars after removal of the seminal vesicles were determined using isoelectric focusing on natural pH gradients. Normal boar spermatozoa focused at a higher pH than spermatozoa from boars without seminal vesicles. The isoelectric point of the latter was increased to a value approaching normal by preincubation in normal seminal plasma. This indicates that seminal plasma alters the membrane surface charge of boar spermatozoa on ejaculation.

Because exposure to seminal plasma enhances the detrimental effects of cold shock on boar spermatozoa (Lasley & Bogart, 1944; Pursel, Johnson & Rampacek, 1972), many procedures for preserving semen by deep freezing employ sperm-rich ejaculate fractions (Pursel & Johnson, 1975; Larrson & Einarsson, 1975), thereby excluding much of the seminal plasma. Our previous studies showed that a basic protein fraction of seminal vesicle origin binds irreversibly to boar spermatozoa at ejaculation (Moore & Hibbitt, 1976) and during cooling promotes sperm membrane disruption (Moore, Hall & Hibbitt, 1976). We therefore tested the possibility that boar spermatozoa could be frozen more effectively in the absence of seminal vesicular fluid.

Summary.

Seminal plasma basic proteins were labelled with ¹³¹I. The efficiency of the labelling was studied by superimposing protein density traces on a radioactive fractionation plot. These labelled proteins were incubated with spermatozoa and shown to bind more readily to spermatozoa from boars after the removal of the vesicular glands than to spermatozoa obtained from their normal litter mates. Most of the labelled protein became bound to the membranes which were isolated by sucrose density gradient centrifugation. The membranes were separated into two bands which equilibrated at the relative densities of 1·150 and 1·165. These fractions consisted of membrane vesicles of different size; the smaller band on the gradient, which equilibrated at 1·165, consisted of denser membrane material.

Summary.

Spermatozoa from intact boars and from boars without seminal vesicles were resuspended in diluent and cooled at different rates to 0°C. Glutamic oxaloacetic transaminase and lactate dehydrogenase activities were greater in the diluents which had contained spermatozoa from intact boars than in those which contained spermatozoa from animals without seminal vesicles. The incubation of seminal plasma from an intact boar with spermatozoa from a vesiculectomized animal before cooling also increased the enzyme activity in the diluent. The factors responsible for this effect were associated with the basic protein fractions of boar seminal plasma, in particular the proteins with haemagglutinating activity which may have been adsorbed onto the spermatozoa. Spermatozoa were exposed to colloidal Fe(OH)₂ ⁺ to determine by electron microscopy the charge on the surface of the plasma membrane of washed epididymal spermatozoa and ejaculated spermatozoa from intact and vesiculectomized boars. Epididymal spermatozoa bound the positively charged particles more readily than the ejaculated spermatozoa from the intact boars, due to the absence of membrane-bound protein.

Summary.

A technique is described for the removal of the seminal vesicles from the boar. The operation was carried out on twelve animals and six of the animals were subsequently trained for semen collection. The seminal plasma from the boars after surgery compared with normal litter mates had a more watery consistency and did not form the characteristic gel during ejaculation. The sperm concentration was 49% lower while the total reduction of sperm number/ejaculate was 78% in the experimental animals, but the ratio of living to dead spermatozoa remained unchanged. The concentrations of citrate and protein were significantly depressed in the seminal plasma of the animals after surgery and the pH increased; the osmolarity remained unchanged. Insemination of gilts with the semen from experimental boars revealed no significant loss of fertility compared with the normal controls. Animals slaughtered up to 17 months after surgery showed no regeneration of the seminal vesicles.