Aspermatogenic Activities Research Articles

Degenerative action on mice and rat testes of polyspermine and its complexes with RNase A

A significant aspermatogenic activity, ascertained by microscopic studies of seminiferous tubules and interstitial tissue, and by the observation of the entrance of immunity and fibrocytic cells in mice injected with polyspermine (PS) or polyspermine conjugated to monomeric or dimeric RNase A (PS-RNase A or PS-dimeric RNase A, respectively), was found either in mice injected or in non-injected testes. Polyspermine and its complexes with RNase A destroyed all spermatogenic and intertestitial tissue, including Leydic cells, as well as their ability to secrete testosterone. The total loss of spermatogenic activity in injected testes is irreversible because spermatogonia cells also were destroyed. The injection of PS into both mice testes determined the total degeneration of testicle tissue in 50% of injected testes. The second half of testes was also partly degenerated, and if they were re-injected, almost all testes were fully destroyed. PS-dimeric RNase A injected once into both testicles produced a stronger degeneration and also the interruption of testosterone secretion in comparison with the effects due to injection of mice with PS or PS-RNase A. In all mice treated with these substances, as well as in rats in which PS was injected twice into their testes, we detected polymorfonucleates, monocytes, plasma cells, lymphocytes and fibrocytic cells. Antibodies against PS, PS-RNase A or PS-dimeric RNase A did not influence the aspermatogenic activity. Animals in which a repeated intra-peritoneal injection was carried out did not lose body mass and remained in good condition, with the exception of mice injected with spermine.

Interactions of the cytotoxic RNase A dimers with the cytosolic ribonuclease inhibitor

Ribonuclease A (RNase A) dimers have been recently found to be endowed with some of the special, i.e., non-catalytic biological activities of RNases, such as antitumor and aspermatogenic activities. These activities have been so far attributed to RNases which can escape the neutralizing action of the cytosolic RNase inhibitor (cRI). However, when the interactions of the two cytotoxic RNase A dimers with cRI were investigated in a quantitative fashion and at the molecular level, the dimers were found to bind cRI with high affinity and to form tight complexes.

Comprehensive comparison of the cytotoxic activities of onconase and bovine seminal ribonuclease

Onconase (ONC) and bovine seminal ribonuclease (BS-RNase) are homologs of bovine pancreatic ribonuclease (RNase A). Unlike RNase A, ONC and BS-RNase can evade the cytosolic ribonuclease inhibitor protein and are potent cytotoxins. Here, the endogenous cytotoxic activities of ONC and BS-RNase are compared in a wide variety of assays. Injections of ONC into one or both testes of mice and rats evokes a stronger aspermatogenic activity than does the injection of BS-RNase. Epididymides exposed to ONC lose mass and all sperm. Testicular tissue is gradually colonized by immunite and fibrocytic cells. Yet, Leydig cells are always present and functional in the ligamented parts of testicles injected with ONC or BS-RNase. ONC is likewise more toxic to mouse embryos than is BS-RNase, both in vitro and in vivo. The antiproliferative effect of ONC on human tumor cell line ML-2 and lymphocytes in a mixed lymphocyte culture is also more pronounced than is that of BS-RNase. The number of granulocyte-macrophage colony-forming units is repressed almost completely by ONC, whereas a five-fold higher dose of BS-RNase does not cause substantial inhibition. In mice, ONC is less immunogenic than BS-RNase but more immunogenic than RNase A. Together, these data indicate that ONC is a pluripotent cytotoxin, and serves as the benchmark with which to gauge the cytotoxicity of other ribonucleases.

PEG chains increase aspermatogenic and antitumor activity of RNase A and BS-RNase enzymes

RNase A (bovine pancreatic ribonuclease) and BS-RNase (bovine seminal ribonuclease) are monomeric and dimeric enzymes, respectively, with aspermatogenic and antitumor activities. While the aspermatogenic and, in some experimental situations, the antitumor effects of the RNase A are only minor, the activity of BS-RNase in these phenomena is very significant. These differences can be annulled by means of conjugation of the enzymes with PEG (polyethylene glycol) chains. Aspermatogenic activity was studied histologically following subcutaneous injections of RNase A and BS-RNase conjugates in ICR mice, and the antitumor activity in athymic nude mice with growing human melanoma with i.p. injection of these conjugated ribonucleases. The experiments proved that RNase A, when conjugated to PEG, produced identical aspermatogenic and antitumour effects as BS-RNase conjugated to this polymer. Immunogenicity of RNase A and BS-RNase did not change substantially after the conjugation with PEG polymers. Binding of produced antibodies to both ribonucleases attached to PEG, however, was substantially reduced.

Ribonucleases Endowed with Specific Toxicity for Spermatogenic Layers

Bovine seminal ribonuclease (BS-RNase) is a dimer in which the subunits are cross-linked by disulfide bonds between Cys31 of one subunit and Cys32 of the other. Dimeric BS-RNase is resistant to ribonuclease inhibitor (RI), a protein endogenous to mammalian cells, and is toxic to a variety of cell types. Monomeric BS-RNase (like its homolog, RNase A) is bound tightly by RI and is not cytotoxic. The three-dimensional structure of the RI · RNase A complex suggests that carboxymethylation of C32S BS-RNase (to give MCM31) or C31S BS-RNase (MCM32) could diminish affinity for RI. We find that MCM31 and MCM32 are not only resistant to RI but are also aspermatogenic to mice. In contrast to the aspermatogenic activity of dimeric BS-RNase, that of MCM31 and MCM32 is directed only at spermatogenic layers. Intratesticular injection of MCM31 or MCM32 affects neither the diameter of seminiferous tubules nor the weight of testes. Also, in contrast to wild-type BS-RNase, MCM31 and MCM32 are not toxic to other cell types. Direct immunofluorescence reveals that MCM31 and MCM32 bind only to spermatogonia and primary spermatocytes. This cell specificity makes MCM31 and MCM32 of potential use in seminoma therapy and contraception.

Experimental allergic orchitis: the isolation and partial characterization of an aspermatogenic polypeptide (AP3) with an apparent sequential disease-inducing determinant(s).

An aspermatogenic polypeptide (AP3) capable of inducing experimental allergic orchitis (EAO) in the guinea pig (GP) was purified from GP testes by sequential delipidation, acid extraction, pH precipitation, ammonium sulfate fractionation, trichloroacetic acid precipitation, gel filtration on Sephadex G-75, preparative isoelectric focusing from pH 3-10 followed by isoelectric focusing from pH 7-10, gel filtration on Sephadex G-75 Superfine under reducing conditions, and reduced acid urea gel electrophoresis. Approximately 250 micrograms (BSA equivalents) of AP3 were obtained from 500 g wet weight of GP testes. On 15% reduced acid urea polyacrylamide gels, AP3 appeared as a single band with an Rf of 0.19. SDS-PAGE showed a single band with a mobility corresponding to a m.w. of 12,500 +/- 1500. The isoelectric point, determined during purification, was 9.90 +/- 0.50. Amino acid analysis of AP3 indicates it is a protein. Gas liquid chromatographic analysis failed to reveal the presence of either hexose or hexosamine, indicating that AP3 is probably not a glycopeptide. Two to 5.0 micrograms (BSA equivalents) of AP3 are capable of inducing severe EAO in 100% of GP tested; 1 to 2.0 micrograms (BSA equivalents) induced EAO in 60% of GP tested. Because AP3 appears to be nonglycosylated and the aspermatogenic activity of AP3 is highly resistant to various denaturing conditions including reduction and alkylation, the primary sequence of the polypeptide rather than higher ordered structure may be more important in defining the determinant(s) responsible for its aspermatogenic activity.

Substitution of ribonuclease in relation to its activity

1. 1. The comparison of the activities of modified forms of AS ribonuclease shows that N-aminoacetylation and iodination are the most convenient labelling methods. 2. 2. Alkylation (carboxymethylation) of AS ribonuclease yielded considerable inhibition of its activity. 3. 3. Oxidation and reduction with substitution of AS ribonuclease resulted total inhibition of its ribonuclease and aspermatogenic activities.

Experimental allergic aspermatogenic orchitis IV. Chemical properties of sperm glycoproteins isolated from guinea pig testes

Of four glycoproteins isolated from guinea pig testes, two were aspermatogenic (types I and IV) and two (types II and III) were inactive. The glycoproteins were rich in carbohydrate, varying from 41.5% to 49.5% carbohydrate by weight. Each glycoprotein had a unique amino acid composition, but in general low levels of tyrosine, tryptophan, and basic amino acids were found along with relatively high contents of serine, threonine, glutamic acid, and proline. Types I and IV glycoproteins were remarkably stable; their aspermatogenic activity was not affected by urea, trypsin, or heating at 100 °C in water or in 1 M HCl for 15 min. Carbohydrate analysis revealed little difference in the monosaccharide compositions of types I and IV glycoproteins, except that only the type I contained sialic acid. In contrast, types II and III glycoproteins lacked sialic acid and fucose and contained much less mannose. Both N-acetylglucosamine and N-acetylgalactosamine were present in all four glycoproteins, and they dominated in the types II and III. Fucose and at least 20–25% of the galactose appeared to occupy terminal positions in type IV glycoprotein as shown by their release after 15 min hydrolysis in 1 M HCl. All of the glycoproteins contained a relatively high percentage of galactose by weight, from 12.6 to 19.3%. The molecular weights of the glycoproteins were estimated by sodium dodecyl sulfate gel electrophoresis to be 47 000, 105 000 and 18 000 respectively for the types I, II and IV; type III glycoprotein showed two major bands, with molecular weights of 41 500 and 22 800. All the above molecular weight values are probably overestimated because of high carbohydrate content. The molecular weight of type IV glycoprotein was found to be 13 000 by ultracentrifugation; a corrected value of 29 000 was calculated for type I glycoprotein.

Experimental allergic aspermatogenic orchitis. II. Some chemical properties of the API protein of the sperm acrosome

The APl protein, a unique aspermatogenic protein localized in the sperm acrosome, exists as a single polypeptide chain of 136 amino acids, as shown by a single band on gel electophoresis in sodium dodecyl sulfate and the recovery of the expected 21 to 22 tryptic peptides on peptide mapping. The APl protein appears to exist in a compact, highly stable conformation, as shown by its resistance to trypsin hydrolysis. Its aspermatogenic activity is not affected by trypsin treatment, by heating at 99 °C for 1 h, by 8 M urea, or by acid conditions. After reduction and alkylation, however, the molecule appears to open up, since it becomes hydrolyzable by trypsin and migrates more slowly on gel electrophoresis at pH 2.7 and 8.6. After alkylation, the APl protein still migrates as a single band at pH 2.7. The APl protein shows microheterogeneity near its isolectric point at pH 8.6; each of five bands shows the same amino acid analysis. Aggregation was not observed following treatment with dimethylsuberimidate. The molecular weight of 15 000, obtained from gel electrophoresis consists of 136 amino acids with a relatively high content of proline, half cystine, glycine, histidine and tryptophan. No galactose, mannose, fucose, glucose, or hexosamines were found; the APl protein is thus not a glycoprotein.

Immunologically induced aspermatogenesis in guinea pigs.

The general background of the aspermatogenic syndrome and its immunological basis is summarized as well as recent additional findings on the question of specificity of tissue antigen and of injection route along with the immunochemical characterization of the aspermatogenic factor in the guinea pig. There was no significant difference in the germinal lesions induced by intramuscular and intracutaneous routes of injection of testicular antigen. 100 mg of antigen were less effective in sensitization than 10 mg and humoral antibody titers also decreased rather than increased at higher levels of antigenic stimulation. Acid-extracted brain was capable of inducing lesions similar to that from sensitization by testis. It is concluded that there may be an autoimmune factor common to these 2 tissues.