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The experiment was done to assess at the impact of cadmium (Cd) on histology and antioxidant enzyme (catalase) activity in different tissues (gills, intestine, and muscles) of freshwater fish, Hypophthalmichthys molitrix. For this purpose, acute toxicity of Cd to H. molitrix was determined. Several concentrations (0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, 35, 37.5 and 40 mgL-1) of Cd were given to fish for 96-hr. The LC50 and lethal concentration (96-h) of Cd was found to be 20.661 and 42.801 mgL-1, respectively at 95% confidence interval. Histological examination of gill tissues showed fusion and curling of secondary lamella, degeneration of epithelium of gills and vasodilation in gill filaments. In intestinal tissues, histological alterations including sloughing and degeneration of epithelial cells of intestinal villi were observed. Moreover, significant (p<0.05) increase in height, width and muscularis mucosa of villi and the significant decrease in the crypt depth and tunica mucosa in intestinal tissues of treated fish were exmined. The muscles of fish showed atrophy, muscle fiber's degeneration and reduction in diameter of muscle fibers were observed. Biochemical analysis showed significant decline (p<0.05) in catalase activity in muscles, intestine, and gills of Cd treated fish. In conclusion, histological and enzymatic changes induced by heavy metals exposure are useful for assessing the harmful impacts of toxicants in various species of fish.

The Houbara bustard is a vulnerable bird species that often experiences higher morbidity and mortality due to infections caused by the multiple drug-resistant pathogens like Salmonella . Studies exploring alternative therapeutics are essential to strengthen antimicrobial stewardship. This study evaluated the antibacterial potential and toxicity of a tungsten oxide nanocomposite (WO 3 /C 3 N 4 , WNC) combined with antibiotics against multidrug-resistant (MDR) Salmonella enterica strains isolated from Houbara bustards. Preparations used in this study included WNC alone and in combination with ciprofloxacin, penicillin, ampicillin, and oxytetracycline. Characterization of WNC through FTIR showed absorption at 799 cm −1 , indicating W–O–W stretching and confirming WO 3 integration while the particle sizes, as identified through SEM, ranged from 20 to 300 nm. The XRD patterns showed fewer sharp peaks for the WNC, confirming its crystalline nature. The antibacterial potential of these products revealed lowest MICs in case of WNC + ciprofloxacin (16.74 ± 4.76 µg/mL) and WNC + oxytetracycline (30.69 ± 10.44 µg/mL), while WNC alone and with penicillin or ampicillin exceeded 100 µg/mL. The toxicity assay showed the WNC + ampicillin significantly reducing mitotic and phase indices in a dose-dependent manner ( p  < 0.05) at 24 and 48 h. All treatments showed significant ( p  ≤ 0.05) dose-dependent genotoxic effects. The study concluded that WNC-antibiotic combinations are effective against MDR Salmonella and relatively safe for host systems, supporting their potential as alternative antibacterial agents.

This study aimed to clone and express chitinase genes from Bacillus proteolyticus strains and characterize the enzymatic properties of recombinant enzymes. Bacillus proteolyticus was isolated from the body of Dermacentor nuttalli and renamed IMH/B-1. Chitin-degrading enzymes were screened via clear zone assay and PCR. The chitinase A gene ( ChiA ) was successfully cloned, and the recombinant plasmid pET28a-rChiA-DP (Dermatestor-derived Protein) was constructed. Recombinant chitinase protein (rChiA-DP) was expressed in Escherichia coli BL21 using IPTG induction and purified by nickel-nitrilotriacetic acid (Ni–NTA) affinity chromatography. Bioinformatic tools were used to predict the rChiA-DP protein sequences, analyse its enzyme family classification, and identify key amino acid residues in its catalytic domain. The enzymatic activity of rChiA-DP, along with its nematode resistance and antifungal effects on Caenorhabditis elegans ( C. elegans ) and fungi ( Aspergillus sp.), was assessed under varied temperatures, pH, metal ions, salt concentrations and substrates. The amino acid sequence of the rChiA-DP contains a chitin-binding domain (CBD) (substrate binding), a fibronectin type III domain (FN3)(structural stability), and a catalytic domain with a typical TIM-barrel molecular structure (catalytic scaffold). SDS-PAGE analysis revealed that the molecular weight of the rChiA-DP was approximately 74.6 kDa, which is consistent with the theoretical predictions. The optimal conditions for rChiA-DP enzyme activity were 40 °C and pH 7.0. Enzyme activity was significantly enhanced by 10 mM Ba 2+ , Tris, K + , and Li + . Organic solvents such as methanol, ethanol, isopropanol, and isoamyl alcohol (10% concentration) also increased the activity. Conversely, positive metal ions such as Cu 2+ , Ni 2+ , Fe 3+ , Zn 2+ and Mn 2+ as well as SDS, DMSO, Tween 20/80 significantly inhibited the activity of the rChiA-DP. rChiA-DPs demonstrated varying degrees of decomposition activity against substrates such as colloidal chitin, chitin powder, nematode eggs, nematodes, shrimp shells, and tick eggs, with the highest activity observed for colloidal chitin (7.53 ± 0.86 U/mL). However, it exhibited no degradation activity on chitosan and tick surface. Compared with the heat-inactivated control group‌ and the s-buffer group, the rChiA-DP treatment significantly reduced the survival rate of C. elegans by 50.4% vs. heat-inactivated control ( P  < 0.01), indicating a potential antiparasitic effect. However, it showed no significant antifungal activity against fungi such as Aspergillus niger or Aspergillus flavus, and the diameter of the inhibition zone was not significantly larger than that of the negative control ( P  > 0.05). This study successfully prepared tick-derived rChiA-DPs and evaluated their enzymatic activity and anti-nematodal activity, providing enzymatic basis for the design of biopesticides targeting insect cuticle.

ABSTRACT A total of 15 microsatellite loci in five hatchery populations of Catla catla were examined for the analysis of genetic diversity and genetic structure patterns. For genomic DNA isolation, dorsal muscle tissues of the sampled fish were used. In terms of the average number of alleles and observed heterozygosity, low to moderate levels of genetic variation were found in all the hatchery stocks. The total number of alleles was found to range from 2.800 to 4.000. In all the populations analyzed, FIS values were found to be positive on an average basis, although some loci had negative values. No HWE deviation was found. The pairwise estimates of FST showed low genetic differentiation between populations. Among the individuals in the populations, much of the variance was found by applying AMOVA. Major cluster patterns among all the populations were measured by constructing PCA, structure, and neighborhood joining tree. In the same cluster are those populations that share the most genetic identity, while populations with the lowest genetic identity fall into a separate cluster. In solving the genetic problems associated with restocking plan and brood-stock management strategies of Catla, the present study inferences will be useful.

Alternative approaches and/or modified approaches to tackle resistance in gut microbes are need of the hour. The current study was planned to find the resistance modulation and toxicity potential of sodium alginate stabilized MgO nanoparticles and antibiotics against Escherichia coli (E. coli) isolated from the gut of Houbara bustard bird (n=105 fecal samples). The preparations consisted of gel stabilized ampicillin (G+A), gel stabilized MgO and ampicillin (G+M+A), gel stabilized MgO and cefoxitin (G+M+C), gel stabilized tylosin (G+T), gel stabilized MgO and tylosin (G+M+T), and gel stabilized MgO (M+G). The fecal samples showed 53% (56/105) prevalence of E. coli which was found to be significantly (p<0.05) associated with most of the assumed factors and resistant to multiple drugs. G+M+T showed the lowest (4.883±0.00μg/mL) minimum inhibitory concentration (MIC) followed G+M+C, G+M+A, G+A, M+G, and G+T. Significant reduction (p<0.05) in MIC with respect to incubation interval found at the 16th hr for G+M+A, G+A, and G+M+C that further remained nonsignificant (p>0.05) onwards until the 24th hr of incubation. In the case of G+T and M+G, significant reduction in MIC was found at the 20th hr and 24th hr of incubation. Ecotoxicology and histopathology trials on snails showed mild changes in MICs of the preparations. The study thus concluded increasing drug resistance in E. coli of houbara bird while sodium alginate stabilized MgO nanoparticles and antibiotics were effective alternative antibacterial composites with mild toxicity.

ABSTRACT Defining the enteric flora of clinically healthy bacterial captive houbara bustards as well as their antibiotic resistance is a critical step to understand the epidemiology of bacterial diseases. An investigation was carried out to identify the intestinal Staphylococcus aureus and Salmonella sp. associated with houbara bustards in captivity and to determine if they are resistant to the currently available antimicrobials. A total of 105 bacterial isolates were recovered by culture-based methods, and bacterial identification revealed that 55.23% (58/105) of them were S. aureus. There were 40.95 % (43/105) samples that contained Salmonella sp. Trends in potential risk factor analysis found male birds (OR=3.18), open environment (OR=1.14), poultry feed (OR=3.12), and winter season (OR=4.23) to be potential risks for getting Salmonella infection. On the other hands, male birds (OR=1.26), natural environment (OR=1.98), poulty feed (OR=5.77), and winter season (OR=1.05) were potential risk factors associated with S. aureus infection. As a result of antimicrobial susceptibility tests, strains displayed multidrug resistance phenotypes against a variety of antimicrobials. The current study showed Staph. aureus to be highly sensitive to Septran (trimethoprim + sulphamethoxazole) (80%), enrofloxacin (70%), ciprofloxacin (70%), fusidic acid (60%), amikacin (60%), and cefoxitin (60%). Trends in relative percentage of resistant strains were higher in case of Salmonella while in case of Staph. aureus, intermediate and sensitive strains showed higher relative changes in percentages. The strength of variation on overall basis in terms of percentages was higher in Salmonella compared to that of S. aureus. The study thus concluded increasing prevalence, decreasing window of potential effects of antibiotics, and increasing potential risks which invites to keep stern preventive measures intact.

The current study evaluated the effects of a methanol extract from Chaetomorpha aerea (a green alga) on non-specific immune responses and resistance against Edwardsiella tarda infection in Labeo rohita. Different doses of the extract (5, 50 and 500 mg/kg of body weight) were injected into the fish intraperitoneally while a control group was injected with 0.2 mL of sterile physiological salt solution. Variations in several immunostimulatory parameters (i.e., neutrophil, serum lysozyme, myeloperoxidase, serum antiprotease, and ceruloplasmin activity), reactive oxygen species (ROS) and reactive nitrogen species (RNS) were assessed after 7, 14, 21, and 28 days of post stimulation. E. tarda culture was injected into the fish after 28 days of post stimulation to induce infection to monitor fish mortality within 14 days. Interestingly, all doses of methanolic extract enhanced neutrophil, lysozyme, and myeloperoxidase activity, ROS and RNS, while a dose of 50 mg/kg was the most effective. Fish injected with this optimal dose were also protected against infection with virulent strain of E. tarda. The results of the study suggest that C. aerea extract is a potential prophylactic agent against bacterial infections in finfish.

The present study was conducted to find out the breeding rate and mortality of Melopsittacus undulatus (budgerigar), a famous species of Australian parrots. A total of 100 birds (50 pairs), kept in a farm house at Bahawal Pur, Pakistan were used in this study. Number of eggs, clutch size, number of hatchings, hatchlings and fledglings were recorded for estimation of breeding rate. Total number of eggs was 537 during whole breeding season. Clutch size varied from 1-9. The hatching and hatchling success was found to be 29.69% and 81.76% respectively. The clutch size and number of eggs laid in breeding season were adequate for rapid increase in population. The hatching rate and fledging rate indicated good reproductive success in captivity.