Iranian Journal of Fisheries Sciences
Volume:21 Issue: 6, Nov 2022

This study aimed to combined effects of salinity and ammonia on physiological responses, liver enzymes, P450 gene expression, and gill and liver Histopathological of juvenile stellate sturgeon (Acipenser stellatus). To this end, a two-stage experiment was carried out. At the first stage, the lethal concentration (LC50 96h) of ammonia in salinities 0 ppt: 7.42 mgL-1, 4ppt:8.24 mgL-1, 8ppt: 9.60 mgL-1, and 12 ppt: 10.22mgL -1 to juveniles of stellate sturgons was determined. At the second stage, 360 juveniles of stellate sturgeons (with a mean weight and length of 15.23±2.17 g and 17±1.96 cm) were exposed to half (50%) median lethal concentration (LC50-96h) (3.71, 4.12, 4.80, and 5.11 mgL-1) under the same salinities for 4 days (8 treatments with 3 replicates a piece). Maximum blood indices (CBC) were observed in combined treatments with salinity and ammonia (P≤0.05). Blood stress indicators (Cortisol, Glucose, Lactate) and blood serum immunity indices (IgM, Lysozyme, Total Immunoglobulin) decreased and increased significantly with increasing salinity and ammonia in combination treatments, respectively (P≤0.05). The activity of GPX and SOD antioxidant enzymes increased in combined salinity and ammonia treatments but CAT decreased (P≤0.05). liver enzyme levels of ALT and AST in the blood serum of juvenile of stellate sturgeons increased in combined salinity and ammonia treatments(P≤0.05). But a significant decrease in the levels of ALP and LDH enzymes was observed (P≤0.05). The highest gill damage was observed in salinity of 12 p p t and also combined treatment of salinity of 12 p p t with ammonia. The most widely noticed symptoms included, Necrosis of Secondary lamellae, Disruption of cartilaginous core. Destruction of the pilar apparatus and congestion in the lamellae, Necrosis of primary lamellae and Fusion of some secondary lamellae. Liver tissue of juvenile stellate sturgeons (A. stellatus) was severely affected by high salinity alone and with ammonia. Complications such as Melanomacrophage center, Necrosis, Sinusoid and Karyolysis were more common. The hepatic P450 gene expression increased from Treatment 5 through Treatment 8 (p<0.05), as the highest gene expression was related to Treatment 8. This suggests that exposure to ammonia along with salinity stress activates the body's internal defense system. Therefore, brackish or saline water at concentrations (ammonia concentrations obtained at different salinities) proposed in this study can be used in aquaculture systems for the juveniles of stellate sturgeon. Moreover, Obtained concentrations of ammonia at different salinities in this study can help the organizations in charge of stock enhancement find the best places for introducing starry sturgeons to a lake or

Vibrio alginolyticus causes severe health problems in marine fish production each year. Among various therapeutic strategies, vaccination is the most economic, efficient and environmentally-friendly approach against microbial infections. Evaluation of formalin-killed Vibrio alginolyticus vaccine aquired from native isolates was carried out using a total of 200 Asian seabass juveniles (55±6.43 g), which were divided among three groups, including (I) control (non-vaccinated), (II) vaccinated with killed V. alginolyticus and (III) killed vaccine with oral booster. Fish were vaccinated intraperitoneally. Blood samples were taken from fish in each group at three, five, and eight weeks after immunization to assess the antibody levels against V. alginolyticus infection. The efficacy of the killed vaccine was appraised five weeks after the start of the initial vaccination by challenging with twofold LD50 (3.66×108) equivalent of the live suspension of V. alginolyticus through intraperitoneal injection. The results of ELISA showed that there were not any significant differences in antibody response among different groups before vaccination (p>0.05). Also, the mean antibody titer of the group immunized killed-V. alginolyticus with oral booster was significantly higher than the other groups five weeks after the vaccination. The vaccined fish demonstrated higher survival rates than the control with relative percent survival (RPS) of 84.62 and 76.92%, respectively. It is concluded that vaccination could be an effective method to protect farmed Asian sea bass against vibriosis caused by pathogenic V. alginolyticus.

This study aimed to investigate the efficiency of conjugating chitosan nanoparticles to letrozole (LET) on masculinization of rainbow trout larvae, Oncorhynchus mykiss. For this purpose, two treatments of LET, 1.5 and 3 mg/kg food, and two treatments of letrozole-chitosan nanoparticles (LET-CS), 0.5 and 1.5 mg/kg were performed with a control group. Treatments began immediately after active larval swimming and continued for 60 days. The results showed that the amount of testosterone during the trial increased significantly (p<0.05), so that the highest amount of testosterone was observed in 3 mg/kg LET and 1.5 mg/kg LET-CS. However, estradiol was untraceable in all treatments. About 66.6, 73.33, 73.33, 76.66 and 43.33% males were observed in 1.5 mg/kg LET, 3 mg/kg LET, 0.5 mg/kg LET-CS, 1.5 mg/kg LET-CS and control, respectively. Despite the drug dosage in LET-CS treatments was half that of LET treatments, the sex ratio did not change among treatments (p≥ 0.05), which showed a positive effect of CS in effectiveness of LET. In general, it can be stated that using CS for the administration of LET could be effective in inhibiting the production of estradiol, increasing the amount of testosterone, and thus changing the sex ratio of rainbow trout.

It has become a hot topic to make optimal use of fisheries products and make them value added as well as find natural food substances which can effectively inhibit oxidative stress and improve human health. Given this, Saurida tumbil muscle was hydrolyzed by Alcalase and Papain at two concentrations of 2 and 4%, and at two hydrolysis times of 90 and 180 min and their antioxidant properties were compared. Antioxidant activity of the protein hydrolysates were investigated by ferrous chelating and ferric reducing, 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2 -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and hydroxyl free radical scavenging activity tests. Samples hydrolyzed by Papain showed higher protein recovery than those hydrolyzed by Alcalase (59.9% versus 20.06%). The protein hydrolysate prepared by Papain enzyme showed significantly higher activity in removal of DPPH (IC50=2.44 mg/mL) and hydroxyl (IC50=3.93 mg/mL) free radicals than those prepared by Alcalase enzyme (DPPH IC50=2.80 mg/mL, hydroxyl IC50=8.59 mg/mL). ABTS radical scavenging activity did not show any significant difference between hydrolyzed samples with Papain or Alcalase enzymes. Hydrolyzed samples with Alcalase enzyme showed higher ferrous chelating activity (IC50=5.33 mg/mL) and ferric reducing activity (optical absorption=0.13±00 at 700 nm) than those hydrolysate prepared by Papain enzyme. Generally, the type of enzyme, its concentration and the time of hydrolysis affected the yield and antioxidant properties of Saurida tumbil muscle protein hydrolysates and hydrolysis with papain at concentration of 4% for 180 min provided the best properties.

Bacterial infections are major limiting factors in shrimp culture that lead to great economic losses to the farmers. This study aimed to investigate the effects of Solen vagina acetone extract (AE) on some immunity parameters and bacterial infection by Vibrio harveyi in Litopenaeus vannamei.  5000 L. vannamei postlarvae were exposed to five concentrations (100, 150, 200, 250, and 300 mg/L) of S. vagina in triplicates for 3 weeks.  A positive control (exposed to the bacteria without any AE) and a negative control (without bacteria and AE) were also considered in this study. Each group contained 600 post larvae. The highest mortality was observed in the groups with concentrations of 100 and 150 mg/L AE and the lowest was observed at a concentration of 250 mg/L AE. None of the concentrations had a significant effect on the physical and chemical properties of water. According to the histopathology analyses, the exposed post larvae showed deformation symptoms in hepatopancreas cells. Based on the results, AE could reduce and prevent mortality caused by Vibrio harveyi. Also, the minimum inhibitory concentration of  AE for V. harveyi was 200 mg/L.

High-throughput sequencing of intestinal microbial DNA using the Illumina platform was implemented to clarify the structure and function of intestinal flora and antibiotic resistance genes (ARGs) abundances in yellow catfish (Pelteobagrus fulvidraco). Species annotation and gene function analysis were performed on the metagenomic sequencing data. Intestinal bacteria were isolated and identified by 16sRNA. The results showed that intestinal flora was highly similar in the three P. fulvidraco. A total of 37 phyla and 788 genera of intestinal bacteria were identified. Proteobacteria, Streptomyces, and Clostridium are the dominant flora with the average relative abundance of 25.71%, 14.75%, and 5.15%, respectively. Six strains were successfully isolated and identified in our experiment. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the primary metabolic pathway is dominated by metabolism and organic systems, while the secondary metabolic pathway is dominated by sensory system, carbohydrate metabolism, replication, and repair. In addition, 499 ARGs of 37 resistance types were identified based on Antibiotic Resistance Genes Database. Tetracycline, polypeptide, macrolide, glycopeptide, and multiple drug resistance were highly abundant. The intestinal ARGs of P. fulvidraco were macB, bcrA, and evgS. In general, rich bacterial diversity and many types of ARG were detected in the intestine of P. fulvidraco. Moreover, probiotics are potentially a good alternative to antibiotic abuse in aquaculture industry. Therefore, analysis of intestinal flora, intestinal flora ARGs and gene functions is beneficial for the artificial farming of P. fulvidraco.

The experiment was carried out for 120 days to determine the optimal dietary protein requirement for the growth of sandfish, Holothuria scabra. The experiment used 12 plastic containers sized 59×47×37 cm, and each container stocked 30 individual hatchery-produced sandfish juveniles (initial weight= 2.70±0.01 g). Experimental diets with different levels of protein, i.e., 10% (A), 20% (B), and 30% (C) as a treatment; it was as dry pellet with 3 mm diameters.  Sandfish were fed with experimental diets once in the afternoon at 2 % biomass. Results of the experiment showed that sandfish fed a 20% protein diet has the highest final weight (5.10±0.02 g), specific growth rate (SGR; 0.53±0.01 % day-1), and feed efficieny (FE; 62.48±0.13) and is significantly different compared to other treatments (p<0.05). On the other hand, feeding with different dietary protein levels did not influence the survival rate greatly (p>0.05), ranging from 85.00-95.83%. The total amino acid content of sandfish juveniles in treatment B was highest (6.62%) and followed by C (6.27%) and A (4.75%). Likewise, the highest fatty acid content was also found in treatment B (0.440%) followed by treatments A and C of 0.416%; 0.332% respectively.  Results of the present study found the best feed was treatment B at 20 % protein content. Moreover, based on statistical analyses, it is suggested that dietary protein requirement for maximum growth of juvenile sandfish is 16%.

This study evaluated the healing effect of black seed essential oil (Nigella sativa; NS) dietary supplementation on skin wound in goldfish (Carassius auratus). Some 48 goldfish were divided into 4 groups, including the control and 3 treatment groups in three replications and kept for study period of 7 days. NS essential oil was added to the basal diet of treatment groups at the concentration of 2% for the NS2 group, 4% for the NS4 group, and 6% for the NS6 group. The control group was fed the basal diet without NS during the experimental period. The 5 mm incision made by scalpel on the right flank of all fishes below the dorsal fin above the lateral line. The fish fed three times a day with assigned diet for a week. Histological investigations approved the effects of NS essential oil on skin wound healing. Diet with 6% concentration of NS6 revealed the improved healing outcomes such as re-epithelialization, muscle regeneration and scale formation rather than NS2 and NS4 groups.

Snakehead fish (Channa striata) is one of the most common and important freshwater species in tropical Asia. Lipid oxidation is one of the major deteriorative reactions taking place in fish muscle during processing and storage, affecting the physicochemical properties and limiting the shelf-life of fishery products. The objective of this study was to investigate the effects of antioxidants on lipid stability, sensory quality and physicochemical properties of snakehead fish fillets during chilled storage. The results stipulated that ascorbic acid and sodium citrate treatments significantly interrupted lipid hydrolysis and lipid oxidation progression in the fish muscle, emanating in lower FFA, PV and TBARS values and higher PL content obtained in the treated samples. The samples treated with ascorbic acid and sodium citrate had significantly higher whiteness values and lower yellowish (b*) values compared to the untreated samples throughout the storage period. The development of lipid oxidation was in high correlations with sensory quality (QI and Torry scores). Based on the QIM and Torry scores, the shelf lives of the untreated, 0.80% sodium citrate treated, 0.25% ascorbic acid-treated and 0.50% ascorbic acid-treated samples were of 10 days, 11 days, 13 days and 14 days, respectively.

It is believed that the marine animals contain many compounds that could be beneficial for the treatment of many diseases. In this study, the acetone extract of Stichopus hermanni was fractionated by a liquid chromatography and then fractions were assayed for terpenoids. The fraction C18 that received a positive response for terpenoids was purified further and characterized by the liquid chromatography, mass spectral, and Thin-layer chromatography analysis. A terpenoid compound, squalene, was identified as the constituent of the bioactive extract fraction. Antimicrobial activity of C18-3 was tested against Bacillus subtilis, Bacillus cereus, Pseudomonas aeruginosa, Salmonella typhi, Proteus vulgaris, Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Nocardia brasiliensis pathogens. The lowest MIC and MBC values were observed in the Bacillus cereus (50 µg/mL) and Staphylococcus aureus (500 µg/mL), MIC and MFC the fungal pathogen Candida albicans (400 and 2000 μg/mL) and was cytotoxic against KB/ C152 and HUT-78/C185 cells (IC50 6.1 μg/mL and 6.29 μg/mL). This research suggests S. hermanni can be used as an alternative source for the separation and purification of squalene compound as a medicinal supplement.

Sustainable development aquaculture industry entails the expansion of environmentally friendly systems. The aim of this study was to evaluate the environmental aspects of biofloc technology system (BFT) in Nile Tilapia (Oreochromis niloticus) culture. This research was performed on two systems including, Biofloc and flow-through system (FTS). Each system had three replications and carried-out for six months and sampled at intervals of 15 days. The density in each 30m3 pond was 1500 juveniles of Tilapia (25 g b/w each). The studied parameters include fish weight, oxygen, temperature, ammonium, nitrite, pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS) of effluent, feed conversion ratio (FCR), specific growth rate (SGR), protein efficiency ratio (PER), survival rate, and cost of culture. The results indicated that temperature, oxygen, nitrite, and ammonium were significant different (p<0.05) and lowest level of NO3(0.004mg/L), NH4 (0.002 mg/L) observed in BFT. There were significantly different between growth indices and all physiochemical factors except for pH, during the time. Effluent factors include BOD, COD and TDS in BFT were significantly lower than FTS (p<0.05). The quality of the effluent in BFT contained only 5%of the food with the effluent and 25% of the food reused in the food chain, while in flow-through, 25-30% of food discharged along with FTS. The water exchange rate in BFT was 1.5m3/day(5%/day) and in flow-through was 30m3/day (0.3 L/s). The cost of feeding in BFT was 25% lower than FTS system. Therefore, the results revealed that BFT, in addition to water quality improvement, leads to less feed consumption, higher quality production, and less environmental pollution.

The resistance of cancerous cells to anti-cancer drugs is one of the most common problems in medicine and therefore, finding new anti-cancer compounds with the least side effects seems to be necessary. The present study was performed to investigate the anti-cancer potential of Padina gymnospora and Acanthophora spicifera, two native algae species of the Persian Gulf, in vitro. In this regard, methanol, chloroform, n-hexane, and ethyl acetate extracts of both algae species were added to cultivated MCF-7 cells at different concentrations (125, 250, 500, and 1000 μg/mL). 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay was used to determine the toxicity effects of algae extracts on MCF-7 cells. DNA isolation and agarose gel electrophoresis were also performed to assess DNA fragmentation induced by these two algae species. Based on the MTT results, the sensitivity of cultivated MCF-7 cells to P. gymnospora and A. spicifera extracts was increased in a dose-dependent manner. The highest concentration of methanolic extract of both algae species significantly affected the MCF-7 cells and led to the highest cell death. Moreover, the IC50 of P. gymnospora and A. spicifera methanolic extracts for the MCF-7 cells were equal to 557.78 and 910.61 μg/ml, respectively, which indicates P. gymnospora has more cytotoxic activity and anti-tumor potency. The lowest concentration of all types of algae extracts was not considerably cytotoxic to cultivated MCF-7 cells. The DNA fragmentation of MCF-7 cells was increased with increasing the concentration of the algal extracts. The highest amount of DNA fragmentation caused by 1000 μg/mL of P. gymnospora and A. spicifera extract; however, methanolic extract of P. gymnospora caused more DNA fragmentation in MCF-7 cells than A. spicifera.

This study aimed to examine the quality changes of rainbow trout (Oncorhynchus mykiss) caught from the farm and live supply center at different times. Rigor mortis, ATP-related components, K-value, and blood parameters of rainbow trout were monitored during storage in the live supply center of rainbow trout. The progress of rigor mortis was accompanied by an increase in storage hours. The initial K-value of fish in live storage was lower than 8%. K-value of the fish climbed to more than 50% at 24 h. After 28 h, K-value of the fish increased to 73% and gradually increased till the end. The K1-value, G-value, P-value, and Fr-value were increased during storage time. The initial glycogen content in the individuals from the farm and live storage were 1.37 and 1.33 mg/g muscle. Significant differences in the plasma cortisol concentration were found in the fish after 24 and 72 h live storage compared to the fish caught from the farm. The L* (lightness) value of the fish fillet from the farm, 24 h, and 72 h live storage was determined as 62.33, 58.12, and 56.21, respectively. After transporting the fish into the live seafood supply center, the total viable count was increased from 2.55 to 4.29 and 5.63 log CFU/ g. These results suggested that the measurement of quality indexes has a great potential for predicting the freshness of rainbow trout during live storage in seafood supply centers.

Folic acid (FA) is an essential water-soluble vitamin, that is unstable in environmental condition and does not regard in vitamin premixes in spite of its importance. In this study 270 beluga sturgeon fingerlings with weight of 5-8 g were fed by various levels of FA: 0.6 (Control/treatment 1), 2.68 (treatment 2), 3.72 (treatment 3), 4.84 (treatment 4) mg kg-1 feed with three replications for 56 days. Effect of treatment groups on growth, hematological, biochemical parameters before and after stress and opercular respiratory rate (ORR) during stress was investigated in fish fingerlings. The results showed the treatments has significant differences on FCR, SGR, feed efficiency and weight gain (p<0.05). the treatments has significant differences with the control group on red blood cells (RBC) count, hemoglobin (Hb) and Hct (P<0.05). Before stress, cortisol and glucose levels among treatment groups had no significant differences, but after stress they had. Minimum and maximum responses in cortisol levels were observed in treatment two (427.92±6.05 ng mL-1) and control groups (830.32±5.97 ng mL-1), respectively. Minimum glucose levels (43.75±1.49 ng mL-1) in control group and the maximum in treatment two (58.25±1.49 ng mL-1) were observed.There were significant differences for ORR in 0-5, 5-10, 10-20, 30-40 minutes during oxygen challenge among treatment groups (p<0.05). But this indicator in 20-30 minutes was not affected by treatments. The results of this study, showed that the fish with FA 3.72 mg kg-1 diet have more resistance against environmental oxygen challenge, therefor can be stated FA may lessen the negative effects of stress in beluga sturgeon fingerling.

Microplastics (MPs), mainly smaller than 5 mm, are vectors for various chemical compounds in the environment, such as pesticides and pollutants. Rainbow trout (Oncorhynchus mykiss) were exposed to two concentrations of chlorpyrifos (CPF; 2 and 6 μg/L), polystyrene microplastics (PS-MPs; 30 and 300 μg/L), and their combination. Significant changes were observed in the activities of catalase (CAT) and glutathione peroxidase (GPx) in mixed MPs and pesticide treatments. Microplastics increased the bioavailability of pesticides in kidney tissue samples for glutathione peroxidase (GPx) and catalase (CAT) enzymes. The activity of glutathione S-transferase (GST) in the liver showed a significant (p<0.05) increase between the treatments of 30 and 300 μg/L MPs compared to the control group. However, for GPx and CAT enzymes in the kidney showed increased activity compared to MPs and pesticide treatments. In conclusion, a mixed concentration of MPs and CPF showed significant effects on CAT, GPx, and GST activities in different tissue samples of O. mykiss.