The ecosystem is continuously exposed to a wide variety of antimicrobials through waste effluents, agricultural run-offs and animal-related and anthropogenic activities, which contribute to the spread of antibiotic resistance genes (ARGs). The contamination of ecosystems with ARGs may create increased opportunities for their transfer to naive microbes and eventually lead to entry into the human food chain. Transduction is a significant mechanism of horizontal gene transfer in natural environments, which has traditionally been underestimated as compared to transformation. We explored the presence of ARGs in environmental bacteriophages in order to recognize their contribution in the spread of ARGs in environmental settings. Bacteriophages were isolated against environmental bacterial isolates, purified and bulk cultured. They were characterized, and detection of ARG and intI genes including blaTEM, blaOXA-2, intI1, intI2, intI3, tetA and tetW was carried out by PCR. This study revealed the presence of various genes [tetA (12.7 %), intI1 (10.9 %), intI2 (10.9 %), intI3 (9.1 %), tetW (9.1 %) and blaOXA-2 (3.6 %)] and blaTEM in a significantly higher proportion (30.9 %). blaSHV, blaOXA-1, tetO, tetB, tetG, tetM and tetS were not detected in any of the phages. Soil phages were the most versatile in terms of ARG carriage. Also, the relative abundance of tetA differed significantly vis-à-vis source. The phages from organized farms showed varied ARGs as compared to the unorganized sector, although blaTEM ARG incidences did not differ significantly. The study reflects on the role of phages in dissemination of ARGs in environmental reservoirs, which may provide an early warning system for future clinically relevant resistance mechanisms.
SUMMARYAmong the vas-based methods on trial, reversible inhibition of sperm under guidance (RISUG ® ), a co-polymer of styrene and maleic anhydride is being projected as an effective alternative to No Scalpel Vasectomy. RISUG offers long-term contraception with safety, efficacy in human trials and can be delivered by no-scalpel injection. Currently, the procedure is under phase-III clinical trial. However, reversal of this vas-based drug-induced contraception needs to be established in animal models prior to clinical trials to ensure its claim as an effective alternative for vasectomy. In the present investigation, the relative suitability of dimethyl sulphoxide (DMSO) and NaHCO 3 for RISUG induced long-term vas occlusion reversal was carried out in albino rats. Animals were allocated into four groups (n = 10), viz., sham-operated control (group-I), vas occlusion with RISUG for 360 days (group-II), vas occlusion with RISUG for 360 days and reversal with DMSO (group-III) and vas occlusion with RISUG for 360 days and reversal with NaHCO 3 (group-IV). A variable response in fertility was observed in different groups. Absolute sterility in group III at all mating intervals, while, zero percent fertility in groups II and IV following 90 days of occlusion was observed. Following reversal restoration of fertility with DMSO at 45 days, whereas, reversal by NaHCO 3 at 30 days was noticed. Ejaculated spermatozoa of RISUG injected and initial intervals of reversed animals exhibited various degrees of abnormalities. The testes exhibited focal degeneration in vas occluded animals. The occluded lumen of the vas deferens contained an eosinated polymer with exfoliated epithelium. Following vas occlusion reversal, a complete regeneration in the vas epithelium was seen. All other parameters remained unaltered. The reversal with NaHCO 3 resulted into an early resumption of fertility when compared with DMSO and the procedure found to be successful, feasible and safe up to F 1 generation. Thus, RISUG provides a hope for reversible male contraceptives.
Reestablishment of fertility, after a male contraceptive method, is of great concern. In this context, RISUG (Reversible Inhibition of Sperm Under Guidance) has been evaluated for its mutagenicity following reversibility with dimethyl sulfoxide (DMSO)/sodium bicarbonate (NaHCO3) in Wistar albino rats. Animals were divided into 7 groups, namely, sham-operated control, vas occlusion with RISUG for 90 and 360 days, reversal with DMSO and NaHCO3 after 90 and 360 days, respectively. The testis, cauda epididymis, cauda epididymal spermatozoa, and serum were evaluated for apoptosis and hormonal status through various assays. RISUG was subjected to Ames test at dose levels of 10, 50, and 100 µL. Results of terminal deoxynucleotidyl transferase nick end labeling and caspase-3 assays in testes and cauda epididymis revealed that the percentage of positive cells in the experimental groups was comparable to sham-operated control. Annexin V assay in cauda epididymal spermatozoa showed slight elevation in group II ( P < 0.05), whereas in the remaining groups, minimum numbers of positive sperms were found. Hormone profile, namely, testosterone, prolactin, cortisol, prostate-specific antigen, and sperm antibody concentration, remained unchanged. In Ames test, no significant increase was observed in the number of revertant colonies on plates containing RISUG in the presence and absence of S9 mix in all 3 strains. Therefore, the reversal of RISUG-induced contraception by solvent vehicle DMSO/NaHCO3 was successful without any toxicity at the cellular levels.
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