The present investigation was conducted to assess the water quality status of the river Buriganga. Water samples were collected from three selected stations in wet (June-August) and dry (November-January) seasons during the years 2017 and 2018. Temperature and Dissolved Oxygen (DO) of water varied from 22.80 to 31.40 °C and 0.22 to 2.74 mg/L, respectively. Electrical conductivity of water varied from 180 to 598 μS/cm while pH ranged from 7.61 to 8.97. This study showed that temperature, DO and Fe were higher in wet season than in the dry season, whereas pH, conductivity and phosphate were higher in dry season than in the wet season. But manganese did not vary in different seasons. It is found that the differences of water quality parameters were significant in seasons (p<0.05) except for Fe and insignificant for stations (p>0.05) except for DO. The results reveal that there were significant differences between sampling seasons (wet and dry) (p<0.05) except for temperature and manganese. A significant correlation (p<0.01) was also found among temperature and other parameters viz. DO, conductivity, pH, phosphate. According to the result obtained in the present study, it may be said that the water quality of the river Buriganga is not acceptable to declare the river-ecosystem as a sound one ecologically.

This study evaluated the effects of different combination of commercial and natural diets (T1: egg yolk, T2: egg yolk+ Artemia, T3: Horlicks, T4: Horlicks+ Artemia, T5: TetraBits, T6: TetraBits+ Artemia, T7: NovoTom, T8: NovoTom+ Artemia) on growth, mortality, RNA: DNA ratio and gene expression of zebrafish for a period of 45 days. Significantly highest length (2.75±0.04 cm) and weight (0.25±0.10 g) gain were recorded in T2 treatment. Lowest length gain (2.00±0.08 cm) and weight gain (0.14±0.12 g) were calculated in T3. Significant highest mortality (65.00±8.66%) was observed in treatment T7 followed by T5 and T8 and significant lowest mortality (20.00±7.64%) was recorded in T2. By molecular analysis, Highest RNA: DNA ratio was found (1.01) in T5 followed by T4 (0.95) and lowest was found in T1 (0.77). Interestingly, a similar result was observed for gh1 (Growth hormone 1) gene expression. Highest gene expression was found in T5 followed by T4 and lowest in T2. Significant down regulation was observed in T2 for gh1 gene. Finally, the study would suggest that zebrafish can be fed with egg yolk+Artemia for better growth performance. The findings could provide a significant contribution to the field of global zebrafish as well as aquaculture research.

No abstract

Expelling antibiotic molecules out of the cell wall through multiple efflux pumps is one of the potential mechanisms of developing resistance against a wide number of antibiotics in Staphylococcus aureus. The aim of this study was to investigate the association between the antibiotic susceptibility profile and the prevalence of different efflux pump genes i.e., norA, norB, norC, mepA, sepA, mdeA, qacA/B, and smr in the clinical isolates of S. aureus. Sixty clinical isolates were collected from a tertiary level hospital in Bangladesh. The disc diffusion method using ten antibiotics of different classes was used to discern the susceptibility profile. polymerase chain reaction (PCR) was employed to observe the resistance patterns and to detect the presence of plasmid and chromosomal encoded genes. Among the clinical isolates, 60% (36 out of 60) of the samples were Methicillin-resistant Staphylococcus aureus (MRSA), whereas 55% (33 out of 60) of the bacterial samples were found to be multi-drug resistant. The bacteria showed higher resistance to vancomycin (73.33%), followed by ciprofloxacin (60%), cefixime (53.33%), azithromycin (43.33%), and amoxicillin (31.67%). The prevalence of the chromosomally-encoded efflux genes norA (91.67%), norB (90%), norC (93.33%), mepA (93.33%), sepA (98.33%), and mdeA (93.33%) were extremely high with a minor portion of them carrying the plasmid-encoded genes qacA/B (20%) and smr (8.33%). Several genetic combinations of efflux pump genes were revealed, among which norA + norB + norC + mepA + sepA + mdeA was the most widely distributed combination among MRSA and MSSA bacteria that conferred resistance against ciprofloxacin and probably vancomycin. Based on the present study, it is evident that the presence of multiple efflux genes potentiated the drug extrusion activity and may play a pivotal role in the development of multidrug resistance in S. aureus.

Aquaculture is the fastest-growing, most dynamic, and vital food-producing sector compared to other food-producing industries. However, aquaculture production is hampered by a variety of bacterial, viral, fungal, and parasitic diseases. Fish farmers routinely apply various types of aqua-chemicals, particularly antibiotics and pesticides, to reduce the disease burden. Antibiotics and pesticides are widely used to increase fish production around the world, including Bangladesh. Between March 2020 and February 2021, a survey was conducted via face-to-face interviews with fish farmers in the Rajshahi district, Bangladesh, to determine the current status of the use of antibiotics, pesticides, and other aqua-chemicals in the rearing of freshwater finfishes. Nine active antibiotics ingredients belonging to 11 trade names of antibiotics, various pesticides, numerous disinfectants, and aqua-chemicals were found to be used in finfish rearing. The renamycin (active ingredient: oxytetracycline) was most commonly used antibiotics by freshwater finfish farmers in the study areas. In case of pesticides, sumithion and timsen were found to be used mostly by fish farmers. In addition, four distinct probiotics were found to be used in aquaculture in the study areas. The present study revealed several issues related to the use of aqua-drugs in the study areas. For instance, the majority of fish farmers (88%) lacked knowledge in the use of aqua-chemicals and antibiotics, and 81% of fish farmers were unaware about the effective dosages of chemicals in fish farming. Thirty seven percent of fish farmers in the study areas reported the indiscriminate use of chemicals. Furthermore, a considerable proportion of fish farmers (72%) reported ignorance about the residual effects of the aqua-chemicals on the aquatic environment and human health. As a result, this preliminary study suggests that the use of antibiotics, pesticides, and other aqua-chemicals in aquaculture should be strictly monitored and controlled by the responsible authorities of Bangladesh. Moreover, further research needs to be expanded on the detection of residues from aqua-drugs and antibiotics in the aquaculture system, and their consequences on the ecosystem and human health.