فصلنامه فیزیولوژی و بیوتکنولوژی آبزیان
سال چهارم شماره 3 (پاییز 1395)

Effects of ultraviolet (UV) radiation on biological matter became an important issue over the past three decades since the first reports of man-made changes in stratospheric ozone layer, which covers and protects the earth’s surface from harmful ultraviolet radiation. The aim of this study was to evaluate and compare the effects of different intensities of UV radiation on the physiological indices of microalgaes Chlorella sp. and Anabaena sp. After preparation of pure samples Anabaena sp. and Chlorella sp. were transferred to flasks containing the appropriate medium and then exposed to UV-C radiation at various time intervals (1, 3, 6 and 12 h) with three replicates. The treated and control samples were placed to growth chamber in favorable conditions of temperature 25±2°C, with light intensity of 2500 lux and light period of 12 hours light and 12 hours darkness in aerated condition for 12 days. The results showed that by increasing the intensity of UV-C radiation up to 12 hours factors like the growth, growth rate, content of photosynthetic pigments and total protein content based on dry weight was significantly reduced when compared to control. Also, in both microalgae, Malondialdehyde (MDA) content was increased in comparison with control group. Furthermore, comparison of the two microalgae revealed that, Anabaena sp. showed more reduction in examined parameters which indicated that the Anabaena sp. is a more sensitive species.

P450 aromatase (CYP19(a)) is the key steroidogenic enzyme responsible for conversion of androgens to estrogens which play a critical role in developmental and sex differentiation. Hence, this study was done to evaluate the effect of Vitex agnus castus hydroalchoholic extract on reproductive performance, sex ratio and expression of CYP19(a), one of the most important gene related to gender, using RT-PCR method in zebrafish. The larvae were fed post-hatching with diets containing extracts of four levels included 0 (control group T0), 5 (T1), 10 (T2) and 15 (T3) g/Kg food for 45 days. For gene expression studies, samples of larvae at 4, 7, 10, 15, 30 and 45 days post-hatching were collected. Expression of β-actin housekeeping genes was normalized as reference gene. Gene expression was evaluated by using 2-ΔΔCT method. The reproductive performance was significantly better in T2 and T3 than other treatments (P

Due to the ability of algae in production of secondary metabolites, they can be a potential source of natural compounds used for drug development and treatment of many diseases. Therefore, present study has been performed to determine the antioxidant and antibacterial activity of aqueous extract of brown algae Iyengaria stellata from the coast of Qeshm, Iran. The evaluation of antioxidant activity of algae extract, investigated by measuring the inhibitory effect of hydroxyl radicals, chelating ability of ferrous ions and total antioxidant activity. Antibacterial activity of extract against four strains of pathogenic bacteria, including Escherichia coli, Salmonella typhimurium, Bacillus cereus and Staphylococcus aureus, was evaluated by disc diffusion method and the results were compared with standard antibiotics. The total antioxidant activity, hydroxyl radical scavenging ability and the ability of ferrous ions chelating were high in algae. But the results of antimicrobial tests showed that the aqueous extract of Iyengaria stellata had no antibacterial effect on studied bacteria. According to the results, brown algae Iyengaria stellata can be used as a potential source of antioxidant compounds in food and pharmaceutical industries.

In this study, the effect of abrupt transfer from freshwater (FW) to the Caspian Sea Water (CSW, 11‰) on ion-regulation capacity of intestine spiral valve were investigated in juvenile Persian sturgeon Acipenser persicus (2.55±0.41g). Immunofluorescence localization of ion transporter proteins including Na,K+ATPase (NKA), Na,K,2Cl– (NKCC) and cystic fibrosis transmembrane conductance regulator (CFTR) were performed 10 days after abrupt transfer. Co-localization of NKA and NKCC in the cytoplasm of enterocytes for both FW- and CSW-acclimated fish indicated that these two proteins were not affected by salinity transfer. Furthermore, CFTR was also found in the cytoplasm but mostly in apical membrane of spiral intestine enterocytes. Based on the obtained results, the main function of spiral valve is nutrient absorption and indirectly has a minor role in ion regulation in juvenile Persian sturgeon. Furthermore, this organ has good physiological development condition in 2-3g fish and it prepares their ability to expose to the Caspian Sea water salinity.

The purpose of the present study was to find the sub-lethal effects of Diazinon and Endosulfan on olfactory responses in Persian sturgeon fingerlings (Acipenser persicus). The fingerlings used in this study were in the range of 7-9 g in weight and 10-13cm in length. For qualitative and quantitative study of environmental effects on behavioral responses, the amino acids glycine and alanine (At the concentration of 0.001 mol per liter as of olfactory stimuli) and Daphnia extract (positive control) and tap water (negative control) each with five replicates were used. Olfactory responses of juveniles in tap water and the sub-lethal concentration (LC10 and 0.1LC50) of the diazinon and endosulfan, after 24, 48 and 96 hours, were evaluated. The average percentage of olfactory responses to olfactory stimuli in both concentrations of LC10 and 0.1LC50 of diazinon with increasing concentration and time compare to the control was decreased. The concentration of 0.1LC50 endosulfan, Showed a greater reduction in the percentage of the average responses of olfaction compare to control. The results suggest that environmental factors are affecting olfactory responses in the Persian sturgeon.

Uncontrolled generation of free radicals can lead to oxidative damage of food and human health problems. Synthetic antioxidants are commonly used in the food and pharmaceutical industries to retard lipid oxidation but their application is strictly controlled due to toxicity and carcinogenicity. Marine organisms that comprise half of the world's diversity are rich sources of bioactive compounds such as peptides, which can be used in the production of functional food. This study reviewed the studies conducted on the antioxidant peptides from marine sources, methods used for their purification and identification and their structures and mechanisms of antioxidant activity, both in vitro and in vivo .Review of studies showed that peptides derived from marine sources show potential antioxidant activity in vitro, in animal models and in food systems. Peptides size, type of amino acids, position of amino acids within peptides and hydrophobicity can influence antioxidant activity of peptides. Antioxidant peptides can be used as functional ingredients to control oxidation of fat and protein in food products. These peptides control the oxidation processes and have potential impact in the treatment and control of human diseases.