Expulsion of plasmid-mediated antibiotic resistance genes in E. coli by ethidium bromide and acridine orange treatment.

Plasmid borne antibiotics resistance is the global threat to healthcare facilities. Such antibiotics resistance is inherited stably within the same bacterial generations and transmitted horizontally to other species of bacteria. The elimination of such resistance plasmid is of great importance to contain dispersal of antibiotics resistance. E. coli strains were identified, screened for the presence of antibiotics resistance by disc diffusion method, and cured by sub-lethal concentrations of Ethidium bromide and Acridine orange. After curing, again antibiotic resistance was determined. Before and after curing, plasmids were extracted by column spin Kit and subjected to 1% agarose gel electrophoresis and antibiotic resistance genes were identified by PCR. The Ethidium bromide was more effective than Acridine orange in eliminating antibiotics resistance and resistance genes bearing plasmids (4, 5, 6, 8, 9, 10 and <10kb). The most frequently eliminated antibiotic resistance was against Imipenem and Meropenem followed by Cefoperazone-sulbactam, Amikacin and cephalosporins in sequence. The loss of antibiotic resistance was associated with the elimination of plasmid-borne antibiotic resistance genes; bla-TEM, bla-SHV, bla-CTX-M, qnrA, qnrB, qnrC and qnrD. Some E. coli strains did not show the removal of antibiotics resistance and plasmids, suggesting the presence of resistance genes on main chromosome and or non-curable plasmids.

Effects of seasonal variation on the biology and morphology of the dusky cotton bug, Oxcarenus laetus (Kirby).

The dusky cotton bug (Oxycarenus laetus, KIRBY) a pest of several crops. The effects of winter and summer on the biology and morphology was investigated. The sampled eggs of dusky cotton bug (DCB) were kept under controlled environment for biological and morphological investigations. In winter, the mating duration of DCB was observed longer significantly (74.2 days), egg development period (3.93 days), an egg laying period (3.6 days) and hatching period (6.66 days) noted longer in winter season. Interestingly, average number of hatched egg (16.8 days) observed significantly higher in summer and the percentage of the hatching of eggs (81.95%) were also observed higher in summer as compare to winter. Whereas, the longevity of all nymph stages in winter longer days as compare to summer nymph stages. Moreover, differences were also observed between male and female development days between winter and summer. In the winter, female DCB development was suggestively higher as compare to summer (24 days). Whereas, the developmental days were noted considerably more in winter for males as compare to summer (14.93 days). On other hand, for morphological parameters, no differences were observed between winter and summer population of DCB.