Mode of action of alkylating agents using a ciliate protozoan as a model system: Part IV--effect of metepa on the synthesis of RNA in the ciliate Blepharisma intermedium.
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Animals↗
Biomedical subjects
S Shivaji
Publications and source records attributed to S Shivaji.
Carotenoids of an Antarctic psychrotolerant bacterium, Sphingobacterium antarcticus, and a mesophilic bacterium, Sphingobacterium multivorum.
The major carotenoid pigments of an Antarctic psychrotolerant bacterium, Sphingobacterium antarcticus, and a mesophilic bacterium, Sphingobacterium multivorum, were identified as zeaxanthin, beta-cryptoxanthin, and beta-carotene. Analysis was based on ultraviolet-visible spectroscopy, mass spectroscopy, and reversed-phase HPLC. Photoacoustic spectroscopy of intact bacterial cells revealed that the bulk of the pigments in S. antarcticus and S. multivorum was associated with the cell membrane. In vitro studies with synthetic membranes of phosphatidylcholine demonstrated that the major pigment was bound to the membranes and decreased their fluidity. The relative amounts of polar pigments were higher in cells grown at 5 degrees C than in cells grown at 25 degrees C. In the mesophilic strain, the synthesis of polar carotenoids was quantitatively less than that of the psychrotolerant strain.
Antarctic Regions↗
Assessment of hyperactivation, acrosome reaction and motility characteristics of spermatozoa from semen of men of proven fertility and unexplained infertility.
Semen from men of proven fertility was compared with that of men with unexplained infertility to determine differences in spermatozoal functions such as hyperactivation and acrosome reaction and spermatozoal motility characteristics. The hyperactivated spermatozoa in both groups could be visualised on the monitor of the Computer Assisted Semen Analyser and they exhibited 'circling', 'thrashing', 'starspin' and 'helical' motility patterns and the mean hyperactivation rates were not significantly different. However, 20% of the men with unexplained infertility did not exhibit hyperactivation compared to only 4% in the fertile group. Furthermore, the semen from infertile men when evaluated for hyperactivation could be categorised into two groups with those having lower hyperactivation (< 10% or < 6% after 4 and 6 h of incubation respectively), forming the first group, and those having a higher hyperactivation rate constituting the second group. In the fertile men such distinct groups were not visible and the percentage hyperactivation ranged from 1 to 16%. No significant differences were observed in the rate of acrosome reaction of fertile and unexplained infertile men. The non-hyperactivated spermatozoa from unexplained infertile men showed a significant increase in path velocity (VAP), curvilinear velocity (VCL) and amplitude of lateral head displacement (ALH) and a decrease in linearity (LIN) and straightness (STR) compared to spermatozoa from fertile men. Furthermore, the hyperactivated spermatozoa from infertile men also showed an increase in progressive velocity (VSL) (only after 2 h of incubation) and LIN and decrease in ALH and beat cross frequency (BCF) compared to spermatozoa from fertile men. The results are discussed in the light of the importance of the above spermatozoal functions and spermatozoal parameters in fertilization.
Acrosome↗
Expression and cellular localization of contraception-associated protein.
Treatment of male rats with ornidazole results in reversible infertility, which is associated with the detection of the contraception-associated protein 1 (CAP1) in epididymal fluid. The protein, which is present in sperm but not detectable in epididymal fluid of fertile rats, seems to be shed from sperm during ornidazole administration. Cloning and characterization of the gene revealed a high degree of similarity between CAP1 and DJ-1 (Wagenfeld et al, 1998b) a protein that was recently found in humans and which has been classified as a novel oncogene. Reverse transcription of total ribonucleic acid (RNA) from various species indicated that a gene similar to CAP1 was also expressed in the testes of hamsters, mice, cynomolgus monkeys, and humans. Detection of RNA expression in rats at the cellular level by in situ hybridization revealed a stage-specific CAP1 expression in the cytoplasm of pachytene spermatocytes (stages IX-XIII), secondary spermatocytes (stage XIV), and round spermatids (stages I-VII). Immunolocalization of CAP1 in rat testis showed a strong staining of elongating spermatids (stages VI-VIII), indicating a translational delay of CAP1 expression. The location of CAP1 on sperm depended on the method of fixation used, with CAP1 being exhibited on the equatorial segment of the sperm head and cytoplasmic droplets. Flow cytometric analysis of sperm from ornidazole-fed rats revealed a significant decline (of 22%-24%) in the amount of sperm surface CAP1 compared with controls, which is associated with an altered location on the sperm head. These observations support a putative role of the protein in the fertilization process.
Animals↗
Semen characteristics of the captive Indian leopard, Panthera pardus.
Semen samples from 11 Indian leopards (Pantherapardus) from 3 different zoos in India were collected by electroejaculation. A computer-aided semen analyzer (CASA) was used for assessing the quality of the semen vis-à-vis sperm motility. The volume of the ejaculate, sperm density, and the number of motile and morphologically normal spermatozoa were found to be 1.57 +/- 1.26 mL, 55.78 million +/- 38.67 million per mL, 57.05% +/- 16.96% and 71.92% +/- 15.32%, respectively. Although the spermatology varied between individuals in the study, Box-Whisker-plot analysis suggested that the distribution was normal (P > .05). The ejaculated sperm were cryopreserved after diluting in test-yolk buffer. The post-thaw motility was 32.14% and did not differ at 30 or 60 days after cryopreservation. CASA indicated that the progressive velocity (VSL) of cryopreserved spermatozoa was decreased and, as a consequence, they moved more slowly than the neat (VSL 76.3 microm/sec in neat vs 53.8 microm/sec in cryopreserved spermatozoa) and the trajectories were less planar. However, both cryopreserved and neat spermatozoa penetrated the zona-free hamster oocyte with equal efficiency (79% neat vs 80% cryopreserved). The study also reports application of CASA for feline spermatozoa and provides information for the first time on the spermatology of the Indian leopard. This baseline data could be used in captive breeding programs. The results are compared and discussed with the available information on other felines.
Animals↗