فصلنامه فیزیولوژی و بیوتکنولوژی آبزیان
سال نهم شماره 4 (زمستان 1400)

The Caspian kutum (Rutilus kutum) is the most important commercially and nutritionally bony fish, which is used to prevent the extinction of this valuable species by induced reproduction to synchronize and increase the level of fecundity in breeding conditions. Previous research has shown that kisspeptin, a super-stimulatory protein in the sex-secreting gland axis, leads to puberty and gametogenesis. However, the sequence of kisspeptin 1 and 2 of R. kutum has not been determined and the ability of this peptide from protein (Kiss1) in reproduction has not been studied so far. In the present study, the kisspeptin10 sequence of R. kutum was determined by CLUSTALW method by designing a primer from the Kiss1 sequence of the same family fish of R. kutum. Doses of 5, 25, 50 and 100μg/kg were used to achieve the best dose of this peptide; and concentrations of 17-α hydroxy progesterone and 17-β estradiol were examined. The results of this study showed that synthetic kisspeptin 10 with an optimal dose of 100μg/kg can be introduce as a suitable candidate for induction of spawning in R. kutum.

This study aimed to investigate the different levels of salinity effect on growth and survival of Anzali wetland freshwater mussels, Anodonta cygnea. Four levels of salinity including 0 (control), 4, 6 and 8 g/L were considered for each of the treatment. 120 samples of fresh mussel with an average initial weight of 50.18±0.68g were distributed randomly between 12 tanks with a volume of 100 L. After 8 weeks of experiment, growth indices were evaluated. The results showed that the weight gain (WG), relative weight gain percentage (RGR), specific growth percentage (SGR) and condition factor (K) were not showed significant difference between control and treatments 4 and 6g/L (P>0.05). With increasing salinity to 8 g/L, growth and survival factors decreased (P<0.05). At the end of the experimental period, samples were separately exposed to high temperature (32°C) and salinity (10g/L) for 72 hours to evaluate the environmental shock. The experiment results showed that the growth and survival of fresh water mussel at salinity of 4 and 6g/L had reliable performance. In addition, the survival rate due to environmental shock had better performances in treatments 4 and 6g/L.

The present study was performed in order to use the seaweed of the Persian Gulf (brown algae Cystoseira trinodis) and also the extraction of fucoidan polysaccharide as an immunostimulant supplementation to improve and enhance some immune parameters of vannamei shrimp. Therefore, 500 shrimp with average weight of 8g were divided into four treatments in triplicate (12 tanks) in a completely randomized design and were fed with diets containing 0, 0.1, 0.2 and 0.4% of fucoidan for 30 days. Results showed a significant effect of fucoidan treatments on the measured parameters (P<0.05). The immune parameters including the number of hyaline, granular and total homocyte cells, superoxide anion, phenoloxidase, superoxide dismutase, catalase and glutathione peroxidase activities in the groups fed with diets containing different levels of fucoidan, especially 0.4% indicated a significant increase compared to the control (P<0.05), while the amount of malondialdehyde showed a significant decrease compared to the control (P<0.05). In general, according to the results of the present study, it can be stated that fucoidan extracted from brown algae Cystoseira trinodis had better performance on improve immune parameters. Therefore, this bioactive compound can be recommended as an immunostimulant in the diet of white leg shrimp.

The present study was aimed to determine the intestinal histopathological changes of common carp fingerling following dietary exposure to Roundup® and the efficacy of dietary inclusion of medicinal plants thyme and rosemary powders to decrease such tissue changes. For this purpose, 300 fingerlings with an average body weight of 15±1.5g were randomly distributed to 5 treatments and fed at 3 different stages as follow: stage 1 with a diet containing 20g/kg of plant powder alone or in combination (treatments 3-5), stage 2 with a diet containing 2.3 mg/kg of Roundup® (treatments 2-5) and stage 3 feeding with diets with neither contaminant nor the medicinal plant powders. Results showed that at the end of the first stage, intestinal tissue had normal microscopic appearance. Pathological changes including necrosis, detachment of intestinal villus, vacuolation in intestinal epithelial cells, infiltration of inflammatory cells along with edema and hyperemia were observed at the end of the second stage in those groups exposed to dietary Roundup® (treatment 2), but those fish previously received diets supplemented with rosemary or thyme (treatments 3 and 4) showed mild tissue changes. Furthermore, simultaneous dietary administration of rosemary and thyme powders (treatment 5) resulted in better tissue protection. Based on the results of the stage 3, after two weeks long recovery period, tissue significant structure amendment was observed in comparison to the previous stage (P<0.05). In conclusion, dietary inclusion of medicinal plant Rosmarinus officinalis and Zataria multiflora powders could reduce the histopathological changes in intestine of common carp fingerling exposed to dietary Roundup®.

The aim of this study was to investigate the antibacterial activity of sea cucumber Holothuria leucospilota and sea urchin Echinometra mathaei extracts on Gram-positive and Gram-negative bacteria, the antioxidant activity and inhibitory power of DPPH. Samples of sea cucumber and sea urchin were collected from around Qeshm Island. Antimicrobial activity of sea urchin was performed by examining the diameter of the growth inhibition zone and in sea cucumber by tube dilution method. Concentrations of 40, 80, 120, 160 and 200mg/mL were used to evaluate the antioxidant activity. The results showed that the antioxidant activity of the extracts of both animals increased with increasing the concentration of the extract (P<0.05) and at the concentration of 200mg/mL reached to 320±5.57 and 420±6.95mg of ascorbic acid/g of extract in sea urchin and sea cucumber, respectively. In all studied concentrations, the antioxidant activity of sea cucumber was higher than sea urchin (P<0.05). In both animals, the concentration of 200 mg/mL of peptide extract with 20.21±5.15 and 56.11±3.76mg of ascorbic acid/g, had the highest free radical scavenging power and in both species, DPPH inhibition activity was lower compared to ascorbic acid (P<0.05). Peptide extracts of all three parts of the gonads, skin and spines of the studied animals were able to inhibit Staphylococcus aureus. Concentrations of 1000 and 1500μg/mL of peptide extract of sea urchin gonad were able to inhibit all bacteria but no significant difference was observed between these two concentrations (P>0.05). The results of the present study showed that sea urchin and sea cucumber can be rich sources of antibacterial and antioxidant compounds. The results of the present study showed that sea urchin was able to show antibacterial effect on gram-negative bacteria.

Today, the use of natural materials in wound dressing has attracted more attention that can overcome the serious environmental problems caused by conventional synthetic materials. In this study, first gelatin was extracted from Caspian kilka fish waste and then used to make composite films in pure form (G), in combination with xanthan (GX) and Anghouzeh oil (GXA). Mechanical properties, swelling index and surface morphology of the films were investigated. The antibacterial and anti-biofilm effects of G, GX and GXA films were also evaluated. The highest tensile strength was recorded for GX film (37.30±0.59MPa) and the lowest value was recorded for pure gelatin film (11.74±0.2MPa). For elongation at break, the highest value was measured in GXA film (54.87±0.21%) and the lowest was in G film (15.61±0.68%). The highest swelling index was recorded for GX film at 300±15.3%. GXA film presented the highest antimicrobial and anti-biofilm activities. The results of these study showed that the film made of gelatin in combination with xanthan and Anghouzeh oil has ideal mechanical and antibacterial properties to use in wound dressing structure.

The main objective of this study was to investigate the effect of blood type of different animals on leech reproductivity, egg numbers, size and weight of each cocoon. To do this, three different blood types of a cow, hens and frogs were studied to measure the rate of medicinal leech Hirudo orientalis reproduction. According to statistical analysis, there was a significant difference between leech final weights (after feeding) (P<0/05). Leeches consumed more blood from cow compared to hens and frogs. They also consumed the least amount of blood from frogs. Results revealed that the cocoons obtained from leeches fed with cow blood were heavier and longer than that of other two groups while, the leeches fed with frog blood showed the lowest weight and length among the experimental groups (P<0.05). Reproduction, survival and hatching rate in leeches were, respectively, 15.29, 90 and 95.29% for cow blood, 11.44, 83.33 and 93.75% for hen blood and 7.17, 76.66 and 92.68% for frog blood. The results of this study indicated that the type of blood can affect the reproduction, survival and hatching rate in leeches. Based on the results of this study cow blood is recommended for leech cultivation. The results achieved in this study can be used in the leech breeding industry.

The aim of this study was to investigate the effect of different prebiotic levels of oyster mushroom (Pleurotus ostreatus) on hematological indices of Nil tilapia exposed to silver nitrate. For this purpose, 120 juveniles of tilapia were fed with diet containing 0 (treatment 1, control), 0.05 (treatment 2), 0.1 (treatment 3) and 0.2% (treatment 4) prebiotic oyster mushroom) for 42 days. Then, 0.5ppm of silver nitrate was added to each group for 16 days. Before and after exposing to silver nitrate, fish blood indices were evaluated. Prebiotics alone had no significant effect on RBC, MCV, hematocrit and hemoglobin (P<0.05). But, treatments fed with prebiotics and exposure to silver nitrate toxin showed an increase in WBC, MCHC (in 0.1 and 0.2 treatments), MCH indices compared to the control group. According to the results, oral prebiotics stimulated nonspecific immunity in tilapia and using mushroom prebiotics reduced the destructive effects of the silver nitrate toxin on blood indices. In conclusion, levels of 0.1 and 0.2% of prebiotic oyster mushroom in treatments which exposed to 0.5ppm silver nitrate toxin could improve the blood factor status of tilapia.