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J. C. BOURSNELL

Summary.

The haemagglutinins in boar seminal plasma are absorbed by ejaculated washed motile ram, bull and rabbit spermatozoa. Washed epididymal spermatozoa also absorb the haemagglutinin, but less avidly.

Considerable motility of the heterologous spermatozoa is still present after 15 min contact with boar seminal plasma. Mixed cell agglutination of bull spermatozoa and red cells gives a reticulate agglutination visible microscopically, and tail to tail agglutination occurs.

The haemagglutinins are absorbed at least as well by washed pig red cell ghosts as by the intact washed erythrocytes. The absorptive power of the ghosts is not destroyed by boiling them in n-NaOH or n-HCl for one hour.

It is presumed that a negatively charged `receptor' group on the surface of the red cell is responsible for the absorption. The receptor does not appear to be connected with erythrocyte sialic acid removable by receptor-destroying enzyme, trypsin or by 0·1 n-HCl.

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U. LAVON and J. C. BOURSNELL

Summary.

Boar seminal plasma, vesicular secretion and epididymal plasma proteins were studied by gel disc electrophoresis at pH 4·5 and 8·6 and by isoelectric focusing in tubes and on plates using ampholines of pH range 3 to 10.

The number of protein bands obtained in the gel disc electrophoresis was fifteen to twenty for all the samples. A similarity between the proteins of the seminal plasma and the vesicular secretion was greater at pH 4·5 than at pH 8·6. The epididymal plasma showed a different separation picture.

The better resolution of the isoelectric focusing revealed a greater number of proteins. Similar protein patterns were found for the vesicular secretion and the seminal plasma in the basic part of the pH range, where the majority of the proteins of these fluids are found. The proteins of the epididymal plasma, on the other hand, possess more neutral isoelectric points and their contribution to the seminal plasma is smaller than that of the vesicular secretion. Only a few of the epididymal plasma proteins and of the minor vesicular secretion proteins could be found in the neutral and acidic regions of the seminal plasma. This is largely the result of the dilution of these accessory secretions occurring during ejaculation.

Differences in the protein pattern of the seminal plasma of various animals could be found. The importance of these differences is as yet unknown.

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U. LAVON and J. C. BOURSNELL

Summary.

The epididymal and seminal vesicular contributions to splitejaculate fractions from boars were analysed for sperm concentration, glycerylphosphorylcholine (GPC), total-N, ethanol-soluble and insoluble N, citrate, zinc and haemagglutinin. The same components were also determined in epididymal plasma (EP), vesicular secretion (VS) and whole seminal plasma (SP). Isoelectric focusing of protein patterns was studied in the fractions.

With the exception of haemagglutinin, the components were present to a major extent in either VS or EP and in lower concentrations in the other secretion. The parameters in VS or EP were positively correlated among themselves and negatively correlated with most of the parameters of the other fluid. The correlation coefficients were not significant in all cases for individual animals, but the degree of significance was greater for the over-all correlations.

The EP components were mainly secreted in the first three or four fractions, but occasionally from fraction four onwards. Those of VS were emitted during the entire ejaculation, the maximum occurring in the sperm-rich fraction or the immediately succeeding fraction. The first fractions were devoid of VS components in only one case.

The majority of the EP proteins could be identified electrophoretically in the sperm-rich fractions, but the protein patterns in the other fractions were similar to those of VS. The results are discussed and compared with previous findings.

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J. C. BOURSNELL and E. J. BUTLER

Summary.

A method of studying boar seminal gel has been devised which enables investigation to be made on the chemical and physical properties of the gel formed in vitro from the bulbo-urethral (Cowper's) gland mucin and either vesicular secretion or seminal plasma. The majority of the haemagglutinin (protein H) in boar vesicular secretion combines with the mucin to form the gel. The content of Zn, Mg and citrate of the natural gel is less (often 0·9 × ) than that of the seminal plasma; this ratio also applies to the Kjeldahl N material imbibed in vitro from seminal plasma or vesicular secretion (as distinct from the N contributed by the mucin). The imbibed aqueous solution of seminal plasma or vesicular secretion can be defined as `interstitial' in that its components are diffusible from the gel matrix into buffer. Part of the interstitial water (possibly as much as 10%) is `bound' physicochemically to the gel matrix and is unavailable for solvation of the seminal fluid components.

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J. C. BOURSNELL and R. R. A. COOMBS

Summary.

A potent red blood cell agglutinating factor, apparently unique to boar seminal plasma, has been demonstrated.

This factor is present in boar vesicular secretion (titre up to 80,000 against pig red cells) but is totally absent in epididymal seminal plasma or in boar spermatozoa.

All red cells examined (from several large mammals, rabbit, human and chicken) are strongly agglutinated.

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J. C. BOURSNELL and E. A. NOBLE

Summary.

Most of the zinc accumulated by boar spermatozoa at 4°C from seminal plasma appears to arise from the low molecular weight zinc ligands. Zinc added to semen in low concentrations (0·1 to 0·6 mm) is preferentially absorbed by the spermatozoa, particularly at 4°C.

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T. K. ROBERTS and J. C. BOURSNELL

A.R.C. Unit of Reproductive Physiology and Biochemistry,Cambridge

(Received 7th June 1974)

Previous publications (Boursnell & Roberts, 1974; Roberts, Boursnell & Brown, 1974; Roberts, Boursnell, Winsor & Mustill, 1974) have shown that the basic boar seminal haemagglutinin (Boursnell & Briggs, 1969) almost certainly combines with zinc in the seminal plasma (Boursnell, Baronos, Briggs & Butler, 1972) to produce reversible opalescence on cooling. The relative magnitude of the opalescence at any one temperature resembles the degree of damage observed when the spermatozoa are subjected to cold shock at that temperature. Boar spermatozoa also showed enhanced absorption of zinc protein at 4°C. Attempts were made to define the nature of the structures binding haemagglutinin. Nelson & Boursnell (1966) showed that substances of high molecular weight inhibited the haemagglutinin reaction, perhaps non-specifically, and no markedly inhibitory low molecular weight material could be found. Certain red cell species-specificities were, however, noted in some haemagglutinin fractions

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T. K. ROBERTS and J. C. BOURSNELL

Summary.

Lactoferrin isolated from sow milk (about 0·6 mg/ml) was shown to be chromatographically homogeneous, an observation supported by electrophoresis and by reaction against monospecific anti-lactoferrin antiserum. Isoelectric focusing showed multiple forms of the protein (i.e.p., 9·3 to 10·0) converted by neuraminidase to one form (i.e.p., 9·65). Boar seminal plasma contains immunologically identical lactoferrin (0·1 to 0·5 mg/ml) which binds strongly to boar spermatozoa.

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J. C. BOURSNELL and P. A. BRIGGS

Summary.

The haemagglutinating protein (or proteins) have been separated from boar seminal plasma largely by gel filtration methods. Electrophoretic studies have shown that the haemagglutinating protein material (now designated Protein H) is positively charged and that it possesses an isoelectric point (i.e.p.) of about 9·4. Earlier electrophoretic observations on mixtures of boar seminal plasma proteins have been verified with the greatly purified Protein A (i.e.p. 8·8) and Protein B (i.e.p. 4·6). It has been possible to explain some hitherto puzzling properties of the boar seminal plasma caused by isolation of various combinations of Protein A, Protein B and Protein H.

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J. C. BOURSNELL and T. K. ROBERTS

Summary.

Zinc alone of the metals present in boar seminal plasma causes an opalescence in normal samples at room temperature. This opalescence is increased by cooling to 4° C, leading in some cases to a definite precipitate which redisperses on warming.

The normal opalescence can be minimized by addition of fractional millimolar amounts of EDTA equivalent to the zinc present. This treatment also abolishes the precipitate which occurs on cooling.