AQUATIC PHYSIOLOGY AND BIOTECHNOLOGY
Year:2019 | Volume:7 | Issue:3|Papers Count:8

This study aimed to investigate the effects of benzo[a]pyrene (BaP) on pituitary-gonad axis of orange spotted grouper (Epinephelus coioides). Fish were injected with 0, 2, 20 and 200 mg/kg of BaP per body weight and were kept under laboratory conditions for 14 days. Plasma samples were taken at days 1, 4, 7, and 14 and changes in 17-β-Estradiol (E2), 17-OH-progesteron, GTH Ӏ and GTH II were evaluated. Alterations of gonad tissue structure also were studied in treated fish. Exposure of fish to BaP resulted in a significant decrease of 17-β-Estradiol, 17-OH-progesteron and significant increase in GTH Ӏ and GTH II plasma levels (P<0. 05). Also, changes were observed in the ovarian tissue of BaP exposed fish including tissue disorganization, increase in choromatin-nocleulos and prenucleulos follicles, increase in interstitial connective tissue and atretic follicles and decrease in developed follicles. Based on the results, decreases in the levels of steroid hormones several days after BaP exposure is due to antistrogenic effects of this compound that acts via decreasing in estrogenic receptors. On the other hand, the increase in GTHs, 7 days after exposure, is because of negative feedback of steroid hormones.

Oxidative stress reflects an imbalance in the redox status of the body and plays an important role in the pathogenesis and development of several human diseases such as cancer. This study aimed to evaluate the antioxidant and cytotoxic effects of peptides derived from enzymatic and microbial hydrolysis of Liza klunzingeri muscle. L. klunzingeri muscle was hydrolyzed using enzymatic hydrolysis with alkalase and microbial hydrolysis by Bacillus licheniformis. The antioxidant activity of samples was measured using DPPH, ABTS and hydroxyl radical scavenging, Fe3+ reduction and Fe2+ chelating effects. The cytotoxic effects of hydrolysates on 4T1 cell line were evaluated using MTT assay. The molecular weight distribution of hydrolysates was determined using HPLC. The microbial sample showed better antioxidant activity in the inhibition of ABTS, chelating and reducing of iron (P<0. 05). The cytotoxic activity of the microbial sample was significantly higher than that of the enzymatic sample (P<0. 05). The percentage of peptides with a molecular weight of less than 1000 Da was 26. 15% in enzymatically prepared protein hydrolysate and 75. 15% in the microbial sample. The protein hydrolyate derived from microbial hydrolysis shows better antioxidant and cytotoxic activity, probably due to the presence of low molecular weight peptides.

The aim of this study was to compare different anesthetic and lethal concentrations of MS222 on blood parameters of Arabibarbus grypus. For this purpose, 18 pieces of fish with an average weight of 150 5. 5g were divided into 3 types of treatments: 1) without anesthesia (control), 2) the treatment with a concentration of 750 mgL-1 of anesthetic agent, and 3) treatment with a concentration of 6250 mgL-1 used for lethal dosage. Blood samples were taken from control, anesthesia (at 0, 6, 12 and 24 hours after anesthesia) and lethal treatments. Hematological parameters including the number of red (RBC) and white blood cells (WBC), hematocrit, hemoglobin, MCV, MCH and MCHC were determined. Hematocrit percentages and hemoglobin levels in the 6 and 12 hours treatments showed a statistically significant decrease compared to the control, 0 hour and lethal concentrations (P<0. 05). Overall counts of RBC in all treatments except the 6 hours treatment showed a significant increase (P<0. 05). MCH and MCV showed a significant decrease in the treatments of 12 and 24 hours compared to the control (P<0. 05). MCHC and the percentage of monocytes in all treatments were higher than control (P> 0. 05). Overall WBC count and heterophil content decreased in 0 to 6 hours, and in the other treatments, there was an increasing trend (P<0. 05). In conclusion, the results showed that anesthesia with MS222 caused slight stress in the fish. This stress caused an initial disturbance in blood parameters that was triggered by a stress response defense and then returned to normal by the adaptation process after 24 hours, so the use of this anesthetic in aquaculture research is unhindered.

Several microRNAs (miRNAs) are involved in the differentiation of neurons and neurogenesis in vertebrates’ brain. However, there is scant knowledge of miRNAs and their target genes in fish. Microarray is recognized as a standard method for a general study of genes that are under miRNAs’ control, although the high cost of this method has limited its application. With advances in bioinformatics algorithms and computer simulation, mRNA targets for miRNAs can be predicted. Therefore, this study tries to determine genes and the relevant miRNAs by investigating the bioinformatics of genes and miRNAs involved in regulating active genes in differentiating neurons and neurogenesis in the brain of zebrafish with the help of Target Scan and DIANA tools. The results of bioinformatics investigations indicate that expression of neurod6b, neurod2, neurod4, olfm1a and olfm1b, gle1, sox11a and sox11b, c adm1b, notch2 and notch1b genes is more likely to be influenced by dremiRNAs during neurogenesis. In conclusion, the product of these genes can be used as a new appropriate candidate in experimental studies for understanding neurogenesis in the brain of zebrafish.

Extensive consumption of surfactants in many industrial and commercial fields and the discharge of sewage containing these compounds into aquatic ecosystems endanger aquatic life. These compounds can bind to various biological molecules such as proteins, nucleic acids and lipids. They can destroy the structure of the cell through the increased production of reactive oxygen species. Therefore, in the present study, the effect of concentrations of 0, 10, 20, 30, and 40mg/L of linear alkylbenzene sulfonate surfactant for 7 days on the intensity of oxidative stress induced in Azolla filiculoides was determined based on malondialdehyde index. Then changes of some growth factors including total chlorophyll content and membrane stability index as well as antioxidant content of the plant including total carotenoid, catalase, phenolic and proline content were investigated. The lowest total chlorophyll content and membrane stability index, and the highest levels of malondialdehyde and proline were observed at 40 mg/L surfactant concentration. However, total phenol content was less affected by surfactant concentrations. In conclusion, the presence of concentrations of 30-40mg/L and above surfactant will cause in oxidative stress and induction of inhibitory effects on some growth indices.

Improvement of a diet of rainbow trout (Oncorhynchus mykiss) brooders with selenium nanoparticles has a great effect on reproductive indices. Selenium is very important for male reproduction and its deficiency and low levels can lead to reproductive disorders such as poor fertility and fetal development. In this study, the effects of different levels of selenium nanoparticles on the reproductive performance of rainbow trout male brooders were investigated. 120 four-year-old male fish weighing 2. 375kg were selected. After adaptation, the fish were divided into four experimental groups (control, 0. 5, 1 and 2 mg selenium nanoparticles per kg diet) with three replications. There was no significant difference in the results of total length of male brooders. The highest fertilization rate (98. 17± 1. 60%) was observed in fish fed 2mg nanoselenium which had a significant difference with other treatments. The highest percentage of egg hatching was observed in the broods treated with 2mg/kg nanoselenium (93. 93± 3. 00). The survival rate of offspring showed that with increasing levels of selenium nanoparticles in males, there was an increasing trend in offspring survival. The increasing trend of fertilization and offspring percentages in male brooders fed 2mg selenium nanoparticles had a significant effect on the final results.

Lactococcosis is a hyperacute systemic disease of fi sh caused by Lactococcus garvieae which has become one of the devastating problems due to its serious economic damage in aquaculture. The ability of bacteriophages to destroy bacterial cells without harming animal hosts makes them potential antibacterial agents for the treatment of bacterial infectious diseases of fish. To isolate the bacterial strains, the suspected fi sh exhibiting clinical signs of hyperacute hemorrhagic septicemia were collected from several rainbow trout farms. Phenotypic and genotypic features of the isolated bacteria were then studied using microbiological and biochemical tests, 16S rDNA PCR amplification and sequencing. Then, seawater, wastewater and fish farm water and soil samples were used to isolate phages against the fish pathogenic bacteria. After cultivating of the samples, three L. garvieae strains and five L. garvieae phages were isolated and characterized. Although slight differences were observed by transmission electron microscopy, all of the phages were classifi ed as members of the family Podoviridae. These phages have the potential to be used for the prevention and control of lactococcosis in the fish farm.

This study aimed to evaluate C-type lysozyme gene expression in the liver, spleen, pancreas and head kidney of breeding Acipenser persicus based on gender with realtime PCR method. For this purpose, sampling of liver, spleen, pancreas and head kidney was done after artificial breeding from 16 fish including 8 males and 8 females. The tissues were transported to the laboratory in liquid nitrogen. After RNA extraction and cDNA synthesis, quantitative real-time PCR was done to examine the relevant gene expression in different tissues. The finding as the first record in this species showed that the C-type lysozyme gene was expressed in all investigated tissues and the expression rate between different tissues had a significant difference (P<0. 01). The highest and lowest expression level of mRNA was observed in spleen and pancreas tissues, respectively. The expression of this gene in different gender of these species showed a significant difference (P<0. 01). So, the expression rate of the C-type lysozyme gene in male tissues was significantly higher than females. Generally, according to the results, it can be stated that the expression rate of the C-type lysozyme gene in different tissues and genders of breeding A. persicus can be influenced by different factors whose potential effects may require further laboratory studies on this filed.