Immunohistochemical detection of calmodulin and calmodulin-dependent protein kinase II in the mouse testis

Calcium/calmodulin and cAMP/protein kinase-A pathways regulate sperm motility in the stallion

In spite of the importance of sperm motility to fertility in the stallion, little is known about the signaling pathways that regulate motility in this species. In other mammals, calcium/calmodulin signaling and the cyclic AMP/protein kinase-A pathway are involved in sperm motility regulation. We hypothesized that these pathways also were involved in the regulation of sperm motility in the stallion. Using immunoblotting, calmodulin and the calmodulin-dependent protein kinase II β were shown to be present in stallion sperm and with indirect immunofluorescence calmodulin was localized to the acrosome and flagellar principal piece. Additionally, inhibition of either calmodulin or protein kinase-A significantly reduced sperm motility without affecting viability. Following inhibition of calmodulin, motility was not restored with agonists of the cyclic AMP/protein kinase-A pathway. These data suggest that calcium/calmodulin and cyclic AMP/protein kinase-A pathways are involved in the regulation of stallion sperm motility. The failure of cyclic AMP/protein kinase-A agonists to restore motility of calmodulin inhibited sperm suggests that both pathways may be required to support normal motility.

Determination of nitric oxide synthase activity and apoptosis of germ cells in different obstruction models

We aimed to determine the changes of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) immunoreactivity and apoptosis after proximal and distal obstruction models on ipsilateral and contralateral testicular tissues. Male albino Wistar rats were randomly divided into three groups (n=30): a control group which underwent sham operations (n=10), a unilateral vasal ligation (n=10) and a unilateral epididymal ligation group (n=10). iNOS and eNOS distribution and apoptosis were studied in both ipsilateral and contralateral testes using quantitative immunohistochemistry. Nitric oxide synthase activity was significantly affected in ipsilateral and contralateral testes cells after vasal and epididymal ligation. eNOS immunoreactivity increased markedly after ipsilateral vasal ligation (ILVL). Degeneration-related changes were also associated with changes in apoptotic rate. Analysis using the terminal dUTP nick end-labeling TUNEL method revealed that apoptotic cell numbers significantly increased after ILVL. p53 and bcl-2 immunoreactivity increased in both experimental groups compared with the sham-operated group. Changes in iNOS and eNOS immunolocalisation were strongly associated with cell damage, because germ cell degeneration was more prominent in the ILVL group. Altered p53 immunolocalisation was also associated with cell degeneration, and a rise in bcl-2 immunoreactivity might be considered to reflect a protective mechanism in the testis. These cellular changes could enlighten understanding of the interaction between testicular functioning and damage.

Identification of Ca2+-dependent calmodulin-binding proteins in rat spermatogenic cells as complexes of the heat-shock proteins

Ca2+-calmodulin (CaM)-binding proteins in rat testes were characterized by assays for CaM-binding activity using the CaM-overlay method on transblots of electrophoresed gels and purification by gel-filtration, ion exchange, and adsorption chromatographies. A major CaM-binding protein complex (CaMBP) was identified and found to be comprised of three proteins with molecular masses 110, 100, and 70 kDa. Amino acid sequence analyses of lysylendopeptidase digests from these proteins indicated that all of the constituents of CaMBP are very similar to the members of the heat-shock protein family, i.e., the 110-kDa protein is similar to the APG-2/94 kDa rat ischemia-responsive protein, the 100-kDa protein is similar to the rat counterpart of the mouse APG-1/94 kDa osmotic stress protein, and the 70-kDa protein is similar to the rat testis-specific major heat-shock protein (HSP70). Immunohistochemistry using anti-CaMBP and anti-CaM antibodies demonstrated that CaMBP was co-localized with CaM in the cytoplasm of pachytene spermatocytes and nuclei of round spermatids. In addition, CaMBP, but not CaM, was localized at a high level in the residual bodies of elongated spermatids. The possible relevance of CaMBP to regulation of cell cycle progression and spermatogenesis is discussed in this paper.