فصلنامه فیزیولوژی و بیوتکنولوژی آبزیان
سال نهم شماره 3 (پاییز 1400)

To investigate the effect of dietary folic acid (FA) on growth performance, serum biochemical indices and liver enzymes status of Siberian sturgeon (Acipenser baerii Brandt 1896), six isonitrogenou and isolipidic experimental diets were formulated to contain graded levels of FA including 0.60, 1.63, 2.71, 3.59, 4.82 and 5.68 mg/kg). Each diet was fed to fish (4.36±0.18g) in a flow through water system for 8 weeks. Examined indices in this study included relative growth rate, daily growth coefficient, feed conversion ratio as well as amount of cholesterol, triglyceride, alkaline phosphatase activity, glutathione S-transferase and malondialdehyde. The results showed that the use of folic acid at the level of 2.71mg/kg increased the growth performance and daily growth coefficient of Siberian sturgeon and caused a statistically significant increase in daily growth percentage of fishes (P<0.05). On the other hand, feed conversion ratio decreased with increasing dietary folic acid level from 0.60 to 2.71 mg/kg and then increased. No statistically significant difference was observed in the alkaline phosphatase activity of fish fed with different levels of folic acid (P>0.05). Glutathione S-transferase activity was not affected by different concentrations of dietary folic acid. Furthermore, different concentrations of dietary folic acid could not make a statistically significant effect on the level of triglyceride, cholesterol and malondialdehyde (P>0.05). The folic acid requirement of Siberian sturgeon based on the daily growth coefficient was estimated to be 1.65 mg/kg diet.

Anthropogenic sounds are emitted from different origins in the natural environments in various time and space domains. These sounds may directly or indirectly affect physiology and behaviour of animals. Sound related spatial distribution changes can be used as an indicator to assess stress related behaviour in aquatic animals. For this purpose, the experiment was designed to investigate the effect of temporal variation of sound exposed zebrafish (Danio rerio) spatial distribution as a behavioural indicator of stress expression. The results showed that sound affected the spatial distribution pattern of zebrafish in such a way that in the brief time span, the fish in continuous (CS), regular intermittent (1:1) and regular intermittent (1:4) tend to spend more time in the lower layer of the tank. Also, in the prolonged time span, fish in all sound treatments irrespective to the temporal pattern tend to spend more time in the lower layer of the tank. Moreover, in the brief time span, there was a significant difference in horizontal displacement in the tank (distance from the sound source) when fish exposed to irregular intermittent (1:1-7) treatment (P<0.01). Also, there were significant differences in horizontal displacement in the tank when fish exposed to irregular intermittent (1:1-7) and continuous (CS) treatments (P<0.05). Further studies are needed to investigate the effects of anthropogenic sounds on both predator and prey and their interactions.

In this study, the lipases-producing Actinobacterial species were isolated from oil-contaminated sites of the hypersaline Lake Urmia. All Actinobacteria isolates were examined for lipase activity by Tween-20 and olive oil as lipid substrates. After DNA extraction, the isolated strains were identified by 16S rRNA gene analysis. Six isolates of halophilic Actinobacteria named LUG03, LUS05, LUG09, LUN15, LUG21 and LUB22 were isolated from the salt sediments of Lake Urmia (Bandar Sharafkhaneh). Among them four isolates showed high potential for lipase production with the highest lipolytic activity for LUS05 strain. Sequence analysis of 16S rRNA identified that the isolates belonged to Streptomyces sp., Nocardiopsis sp., Glutamicibacter sp. and Brachybacterium sp.

The aim of this study was to evaluate the effects of herbal supplements including Zataria multiflora essential oil and ginger (Zingiber officinale) powder in order to achieve goals such as growth performance, immunity system and blood parameters of common carp. The fishes with the average weight and length of 107.08±0.58g and 20.01±0.08cm respectively, were fed during 35 days. The experiment was done with 3 treatments with triplicate including a control (T1), Z. multiflora essential oil (T2) with 10g/kg feed and ginger powder (T3) with 10g/kg feed. Growth indices and nutrition performance, hematological parameters, immunity system and digestive enzymes were measured. Results showed there were significant differences in Wf, SGR, FCR, PER and LER in the treatments (P<0.05). The lowest value of FCR was obtained in treatments fed with ginger powder which was 1.38 (P<0.05). The results revealed that the highest amount of protease and lipase enzymes were obtained in the ginger powder treatment which had a significant difference compared to the control treatment (P<0.05). The highest hemoglobin content of common carp was obtained in the treatment containing ginger powder, which was statistically significant compared to the control treatment (P<0.05). The percentage of blood hematocrit in both experimental treatments was lower than control (P<0.05). However, findings of this study suggest that ginger powder performance was positive and significant on growth indices and immunity system compared to oregano essential oil.

Attainment of soluble recombinant protein in high quantity is a critical demand in all types of biotechnology. Between the available general and protein-specific techniques used for enhancing the protein solubility, the co-expression of desired protein with molecular chaperones seems to be a proper solution to assist the folding of newly synthesized protein and reduce the inclusion bodies formation, however the effectiveness of different chaperones varies widely. In order to evaluate the efficiency of fish chaperones in increasing the solubility of recombinant proteins, cloning and simultaneous expression of Esox lucius Hsp70 (El-Hsp70) and the µ-class glutathione S-transferase from Rutilus kutum (Rk-GSTµ) was performed on E. coli host. In order to investigate the protein-protein interaction, the SDS-PAGE electrophoresis and measuring the specific activity of Rk-GSTµ was applied. Since the solubility and specific activity of Rk-GSTµ were increased in co-expressing cells, this work has provided another promising finding on the positive role of chaperones in enhancing the soluble content of expressed recombinant proteins.

Fish is in the highest level of aquatic food chain and has the ability to biologically magnify heavy metals, even at low concentrations in the environment. Biochemical methods and measuring blood parameters are among the important biological indicators that are widely used in assessing the health status of fish. The aim of this study was to investigate the effects of silver nanoparticles on thyroid hormones, growth hormone, blood factors and liver enzymes of common carp (Cyprinus carpio). In this study, 150 fish with weight of 12-15g after obtaining acute toxicity (LC50 96h), randomly exposed to concentrations of 0 (control), 5, 10 and 15 µg/L of LC50 96h silver nanoparticles with three replications for 7 days. At the end of the experimental period, blood samples were withdrawn by puncturing the vein in the fish tail. The results of this study showed that silver nanoparticles led to a significant difference in the number of white blood cells, percentage of neutrophils, lymphocytes and eosinophils and also amount of ALT and AST in the treatments (P<0.05). Also silver nanoparticles have negative effects on blood and biochemical parameters of common carp.

To evaluate the effect of cadmium on metallothionein gene expression changes as a biomarker, three experimental treatments including 200 (first treatment), 400 (second treatment) and 800 (third treatment) µg/L and a control (without cadmium) were considered with three replications. After 14 days’ period treatment with water soluble cadmium, the expression of metallothionein gene was investigated in the liver tissue of Persian sturgeon (Acipenser persicus). RNA extraction in liver tissue and cDNA synthesis were performed and the accuracy of gene expression and expression changes were evaluated by qualitative RT-PCR and quantitative Real Time PCR methods, respectively. Results of metallothionein gene expression after statistical analysis showed that the increasing cadmium concentration led to changes in metallothionein gene expression in the liver tissue of Persian sturgeon and at a concentration of 200µg/L showed a significant increase in metallothionein gene expression (P<0.05). Therefore, it can be concluded that changes in metallothionein gene expression in Persian sturgeon can be considered as a biomarker of exposure to cadmium heavy metal at a concentration of 200µg/L. But, in general, an increase in water-soluble cadmium does not always lead to an increase in gene expression in the liver tissue of Persian sturgeon, and probably, other mechanisms are involved in the transport of this metal in the body of Persian sturgeon.

The aim of the present study was to evaluate the osmoregulation ability of zander (Sander lucioperca) at two larval stages including before (group “a”) and after (group “b”) yolk sac absorption. Both groups were exposed to freshwater (less than 0.5‰ salinity), estuarine conditions (7‰) and Caspian Sea water (12‰) for 96h. Larva survival rate and chloride cell number, size and the its surface percentage were examined by classical histology using H & E staining and immunolocalization of Na+,K+-ATPase. Survival rate was 97% for both groups in freshwater and was 86% and 97%, respectively for group “a” and “b” at 7‰ salinity. At 12‰ salinity, all larvae in group “a” died while 20% of group “b” survived. The size of skin chloride cells did not change in the face of different salinity. At the end of the experiment, the number and the surface percentage of chloride cells significantly increased in the group “a” at 7‰ salinity and in group “b” at 12‰ salinity (P<0.05). The results showed that in the Caspian Sea zander larvae, the function of skin chloride cells in osmoregulation improved with development of body and it could act in such a way that the survival rate in the post-yolk sac uptake stage was more than the pre-yolk sac uptake stage exposed to salinity.