Shrimp aquaculture has become a vital industry, meeting the growing global demand for seafood. Shrimp viral diseases have posed significant challenges to the aquaculture industry, causing major economic losses worldwide. Conventional treatment methods have proven to be ineffective in controlling these diseases. However, recent advances in RNA interference (RNAi) technology have opened new possibilities for combating shrimp viral diseases. This cutting-edge technology uses cellular machinery to silence specific viral genes, preventing viral replication and spread. Numerous studies have shown the effectiveness of RNAi-based therapies in various model organisms, paving the way for their use in shrimp health. By precisely targeting viral pathogens, RNAi has the potential to provide a sustainable and environmentally friendly solution to combat viral diseases in shrimp aquaculture. This review paper provides an overview of RNAi-based therapy and its potential as a game-changer for shrimp viral diseases. We discuss the principles of RNAi, its application in combating viral infections, and the current progress made in RNAi-based therapy for shrimp viral diseases. We also address the challenges and prospects of this innovative approach.

A global interest in Silver Barb (Barbonymus gonionotus) cultivation has arisen because of a combination of declining wild stock and a steady increase in demand and market value. The purpose of the current investigation was to evaluate the impact of extreme water temperature changes on growth, hemato-biochemical responses, pepsin enzyme activity and gill histomorphology of B. gonionotus. Four distinct temperatures (22, 26, 30 and 34 °C) were applied in the laboratory (22, 26, 30 and 34 °C) in triplicate glass aquariums (150 L each). At 30 and 22 °C, respectively, the highest and the lowest length and weight gain, specific, daily and relative growth rates were noted. At 30 °C the lowest FCR was recorded (1.42 ± 0.04). The values related to hematology and biochemistry were found to be within normal ranges; nevertheless, there was a notable variation in the parameters when the temperature changed. Hematological results revealed that RBC, HB, PLT, HCT and PMV levels were significantly higher in groups 30 °C with respect to others. It was evident that cold and heat shock stress was present due to the decline in hematocrit levels and rise in WBC values. Regarding the biochemical responses, the level of triglycerides, cholesterol, AP, Ca⁺, HDL, and HDL/LDL ratio increased significantly higher at 30 °C. Glucose, total protein, albumin, Na⁺, K⁺, Cl⁻¹, AST, bilirubin, uric acid, and LDL levels were significantly higher at 22 °C compared to other temperatures. There was a higher pepsin activity between 26 and 30 °C while the digestive somatic index (I_DS) was disproportionate. Histological examination demonstrated the well-shaped gill tissues at 26 and 30 °C compared to distinctive pathology in other temperature treatments. As an end note, the results of the experiment indicated that B. gonionotus should be cultured at 26–30 °C to maximize the overall productivity and the health condition of this economically important fish species.

Planarians including Dugesia ryukyuensis (Dr) have strong regenerative abilities that require enhanced DNA replication. Knockdown of the DUT gene in Dr, which encodes deoxyuridine 5′-triphosphate pyrophosphatase (dUTPase), promotes DNA fragmentation, inhibits regeneration, and eventually leads to death. dUTPase catalyzes the hydrolysis of dUTP to dUMP and pyrophosphate. dUTPase is known to prevent uracil misincorporation in DNA by balancing the intracellular ratio between dUTP and dTTP, and contributes to genome stability. Nevertheless, the catalytic performance of Dr-dUTPase has not been reported. To confirm the catalytic activity of Dr-dUTPase, we cloned and expressed Dr-DUT in E. coli. Then, we purified Dr-dUTPase using His-tag and removed the tag with thrombin. The resulting Dr-dUTPase had the leading peptide Gly–Ser–His– originating from the vector at the amino terminus, and a mutation, Arg66Lys, to remove the internal thrombin site. We observed the hydrolysis of dUTP by Dr-dUTPase using Cresol Red as a proton sensor. The Km for dUTP was determined to be 4.0 µM, which is similar to that for human dUTPase. Dr-dUTPase exhibited a preference for dUTP over the other nucleotides. We conclude the Dr-dUTPase has catalytic activity.

Drying is an effective means of reducing moisture content of perishable fruit and vegetables to a safe storage level and reduce post harvest loss. This study was conducted to evaluate a solar tunnel dryer for drying cabbage in comparison to traditional open sun drying at the advanced drying lab of the Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh. Salt pre-treated cabbage was used for drying inside the dryer and open sun drying. The parameters like solar radiation, temperature, relative humidity, and moisture content were measured using standard instruments during the experiments. The results showed that the maximum peak temperature inside the drying chamber was 45 °C during mid-day (12 pm) when solar radiation was 600 w/m2 and in an average inside temperature was approximately 30°C to 40°C in a full sunny day (9:00 AM to 04:00 PM) when average solar radiation was 321±115 W/m2. The moisture content of sliced cabbage was reduced initially 94.42, 90.18, and 92.24 % (w.b.) to 4.85, 15.84, and 15.71% (w.b.), and drying time of the dryer was 28, 21, and 19 hours in 1st, 2nd, and 3rd trials, respectively. The drying rate and drying efficiency were found 0.15 kg/hr. and 8.22 %, respectively in tunnel dryer and 0.02 kg/hr. and 3.38 %, respectively in open sun drying. The color and texture of the solar tunnel dried cabbage were better than the open sun drying method. Further experiments are required for estimating drying capacity with the operating cost of the solar tunnel dryer when the dryer will be used with its full capacity.

The study investigated the optimum dose of 17 α-methyltestosterone (17α–MT) for maximum sex reversal and growth performance of Nile tilapia (Oreochromis niloticus). Using a completely randomized design, three treatments (Control, T-1, T-2, and T-3) in triplicates were set up. The control group diet was devoid of 17α–MT. The remaining three groups, T-1, T-2, and T-3, were fed feed that contained 30, 60, and 100 mg kg-1 of 17α–MT, respectively. Fry of three days old were stocked at a rate of 100 per tank. They were fed with experimental diet for 28 days. After the hormone treatment and 90 days of rearing the highest survival rate was found in the control group. Gonadal squashing of O. niloticus showed different sex ratios for different treatments. The control group showed a normal sex ratio of 48.33% males and 51.67% females. The experimental group T-3 showed the highest percentage of males (98.33%) followed by T-2 (93.33%) and T-1 (76.66%). After 90 days of rearing, although the study found the highest mean length (82.12±1.5 mm), weight (26.74±0.08 g) and SGR (9.17±0.05%) in the treatment T2, these growth performance parameters did not differ significantly with the result of treatment T3. The Nile tilapia's sex ratio has been found to be more affected by a higher dose, or 100 mg 17α–MT kg-1 of feed. With the increase of hormone inclusion level, sex reversal percentage increases. Higher doses of 17α–MT have also a positive impact on Nile tilapia growth performance. Growth increases with the increasing 17α–MT level up to 60 mg in the diet of O. niloticus. Based on the study, the recommended dose for producing maximum mono-sex male tilapia in commercial hatcheries may be 100 mg 17α–MT kg-1 feed. Vol. 9, No. 3, December 2022: 377-384

A 60-day experimental trial was conducted to evaluate the effect of different stocking densities, probiotic supplementation, and a biofloc system on the growth and physiological responses of Puntius sophore in laboratory conditions. P. sophore (8.64 ± 1.24 g) was obtained from the Brahmaputra River, Mymensingh, and immediately transferred to a flow-through water system. In experiment 1, fish were subjected to three treatments (20 fish per 400 L as LD, 25 fish per 400 L as MD, and 30 fish per 400 L as HD), and similarly, in experiment 2, three different types of diets were provided (control diet (D1), biofloc (D2), and a probiotic-containing diet (D3)). Three replications were used in the completely randomized experimental design. Growth parameters, viz. TLG, BWG, FCR, FCE, SGR, RGR, and DGR, were significantly influenced by stocking density and probiotics (p < 0.05). The highest growth rate was observed in LD and in D3. The lowest FCR was also observed in LD and in D3, while highest was in HD (30 fish per 400 L) and in D2. Though stocking density does not impact the blood profile, with the exception of WBC, in the case of feeding regime, WBC, RBC, MCV, MCH, and PLT levels differed significantly (p < 0.05); however, all haematological measures were within the normal range in both experiments, and the fish’s physiological conditions were better in LD and feeding with probiotic supplementation (D3). The results obtained from this study suggested that the welfare of P. sophore is adversely affected by high stocking density and increased growth and physiological conditions when cultured with LD and supplemented with probiotics.