فصلنامه شیلات
سال شصت و نهم شماره 4 (زمستان 1395)

Aeromonas hydrophila is the causative agent of hemorrhagic septicemia in freshwater fish, especially in carp. Several factors are involved in the pathogenesis of the disease by this bacterium but the mechanism is yet to be investigated. Virulence genes are the most important pathogenicity factor in A. hydrophila. In this study, 30 isolates were identified as A. hydrophila by common biochemical methods and detection of 16S rDNA molecular marker using PCR method. PCR were then used to identify Aerolysin (aerA), Elastase (ahyB) and Lipase (lip) virulence genes using specific primers for each gene. The highest frequency belonged to the elastase gene (70%) and the aerolysin gene had the lowest abundance with (53.3%). For these three virulence genes eight different profiles were considered that the lipﶨ爇窰 isolates (33.3%) was the most frequent profile and lipﶨ/aerA (3.3%) was the lowest frequency obtained. Mortality was measured and determined after injecting A. hydrophila containing each of eight different profiles to the common carp fry. The mortality rate of infected fish with lipﶨ爇窰 and lip-/ahyBﶧꬃ profiles was higher from other groups and control group. In diseased fish, signs of darkening skin, shortening of gills and abdominal and vent petechial hemorrhages were observed. These results indicate that aerolysin, elastase and lipase virulence genes increase the pathogenicity of the A. hydrophila.

This study was conducted to investigate the effects of dietary nucleotide and P. acidilactici on the growth performance, some innate immune responses and serum biochemical parameters as well as the resistance of rainbow trout (Oncorhynchus mykiss) against Aeromonas hydrophila. Nine experimental diets were formulated to contain three dietary nucleotide levels (0, 1 and 3 g kg-1 diet) and three P. acidilactici levels (0, 0.1 and 0.3 g kg-1 diet) according to a 3×3 factorial design. Each diet was randomly assigned to triplicate groups of 30 fishes (with the average initial weight of 63.4±1.62 g) per tank. At the end of an eight week feeding trial, several innate immune responses and serum biochemical parameters including serum total protein, lysozyme, serum alternative complement (ACH50), cholesterol, triglycerides, albumin, and glucose levels and also fish performance (survival, weight gain, specific growth rate (SGR) and feed conversion ratio (FCR)) were measured. The results indicated that lysozyme and ACH50, were all increased significantly (P0.05). The results also showed that the interaction between dietary nucleotide and P. acidilactici significantly improved fish performance in the rainbow trout. Furthermore, at the end of the feeding trial, ten fish per each replicate were intraperitoneally injected with A. hydrophila to determine the disease resistance. The results showed that the supplementation of the rainbow trout diet with dietary nucleotide and P. acidilactici remarkably increased resistance to A. hydrophila infection; the highest resistance was also observed in the interaction groups (dietary nucleotide × P. acidilactici). Overall, the combination of dietary nucleotide and P. acidilactici showed more advantages than the administration of individual ones. The best combination of them for the rainbow trout was 3 g kg-1 dietary nucleotide and 0.1 g kg-1 P. acidilactici.

Fish meat is so perishable than other meat and during storage its quality decreased rapidly. The aim of this work was to evaluate the effect of chicken feet gelatin and carrageenan edible film with chitosan and cellulose nanoparticles on rainbow trout stability during refrigerator storage period. In present study edible film prepared with 2.5 and 5% extracted chicken feet gelatin and carrageenan. Edible film sprayed on fish fillet and their quality and stability during 16 days refrigerator storage evaluated. Results of this work depicted low antibacterial effect of gelatin 5% and carrageenan 5%. Bacterial count of Gelatin 2.5% at day 12 was 7.04 Log cfu/g and control treatment at day 8 was 7.17 Log cfu/g that were exceeded the limit. PH had decreasing and subsequently increasing trend (P

Technical management in agricultural productions is a key factor for increasing the yield and reducing the cost of production. For this purpose, the technical efficiency of warm water fish farms was assessed during growing season 2014. The required information was collected from 57 growers by using questionnaires. Data envelopment analysis and genetic algorithm were applied to analyze the information. The results of data envelopment analysis showed that the total energy consumption in optimum situation is 158515.5 MJ ha-1. The highest save of energy among inputs in optimum situation (without any output reduction) belongs to fish input (9.27%). Based on the genetic algorithm results in optimum situation the total energy need is 43766.51 MJ ha-1 (with 26% energy saving).

Chlorpyrifos is an organophosphate pesticide that is widely used to control the pests in agricultural fields. The aim of this study is to determine the effects of sublethal concentrations (0.1, 0.05 and 0.02 mg/l) chlorpyrifos on the liver enzymes activities and oxidative enzymes (superoxide dismutase and catalase) in common carp (Cyprinus carpio) on 1, 7, 14 and 21 days. The present results suggest that a significant increase in the activities aspartate aminotransferase (AST) and alanine aminotransferase (ALT) fish exposed to pesticide chlorpyrifos compared with a control group (P

Phytoestrogens are natural compounds with the potential to elicit negative effects on the endocrine systems and reproduction of aquatic life. In this study, the effect of Genistein and β-sitosterol on some reproduction indicators of Caspian Kutum (testosterone, 17β-estradiol, aromatase and EROD) were studied. A total of 49 none-ripened Kutum’s exposed to 3 different levels of Genistein and β-sitosterol (10, 50, 500 ng/l respectively). After 21 days, serum, liver and ovary were sampled and mentioned parameters were measured according to exist protocols. The result showed high level of Genistein lead to increased 17β-estradiol and aromatase activity. Also, treated fish with β-sitosterol showed high level of testosterone and EROD induction. While, both of them had no significant effect on Ca level. According to this study, high concentration of Genistein (500 ng/l) could act as a stimulant endocrine system and might cause changes in steroid hormone levels and aromatase activity. It was also found that the same concentration of β-sitosterol could induce EROD activity and increasing testosterone level. It could alter biosynthesis of sex hormones and disrupt the function of endocrine system. It seems that these compounds could effect on the endocrine system of Kutum and reduce reproduction performance of Kutum in the long period.

To study the pharmacological characteristics of marine natural products has led to the discovery of bioactive substances. The source of bioactive natural products biological and chemical structural properties marine environment cannot be seen of other natural products terrestrial plants and animals. This study aimed to evaluate and compare the antibiotic properties of n-hexane and acetone extracts were taken from four species of invertebrates. Geyser (Phaulasia nigra), sponge (Cliona spp.), carpet anemone (Sarcophyton spp.) and starfish (Pentaceraster spp.) species were collected from the Island lark. Then extraction was carried out by n-hexane and acetone solvents soaking. Antibacterial effects on Escherichia coli bacteria dilution method were at first Agar diffusion method and then performed to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). N-hexane extracts derived from any of the four species studied had antibacterial properties. Estonia extracts derived from sponge and starfish in concentration of 10 and 40 mg/ml was bacterial growth inhibition and a concentration of 20 mg/ml acetone extracts derived from the sponge has antibacterial properties and cytotoxicity. Maximum zone of inhibition was 16.2± 1.5 mm by the sponge acetone extract and minimum zone of inhibition was 0.2± 0.3 mm by the starfish acetone extract. The results show Estonia sponge and starfish extracts contains compounds with antibacterial effect but the cytotoxicity of Estonia sponge extracts in this study much more.

In this study, the antibacterial effects of Mentha piperita (0, 0.4 and 0.8%) and nisin (0, 0.25 and 0.75 µg/ml) alone and together for control of Streptococcus iniae in rainbow trout (Oncorhynchus mykiss) fillets were evaluated at 4 and 8°C. The results showed that M. piperita essential oil had a higher inhibitory effect in both temperatures of 4 and 8°C compared to nisin. At 4°C, the essential oil of M. piperita and nisin in comparison to the control treatment had a better effect and in combined treatment, 0.75 μg/ml nisin and 0.8% M. piperita essential oil, growth of Streptococcus iniae from day third stopped. Antimicrobial activity was also increased by increasing the amount of nicine and M. piperita essential oil and at 8 °C, this combination was able to prevent bacterial growth until the ninth day. The results of this study showed that M. piperita essential oil had more antibacterial activity compared to nisin against S. iniae. In both treatments, with increasing levels of nisin and M. piperita essential oil, the inhibitory activity increased at a temperature of 4 and 8 °C in comparison with control and treatments with lower amounts of nisin and M. piperita essential oil. At both storage temperatures, the best performance was observed in treatment with the highest level of 0.75 μg/ml nisin and 0.8% M. piperita essential oil.

The present study was to scrutinize the protective effect of dietary cinnamon essential oil supplementation on reducing the toxicity of aflatoxin B1 to rainbow trout fingerlings regarding hematological indices, serum biochemistry and liver histopathology. To that end, fish were randomly allotted into 6 distinct treatments composed of different combinations of three dietary aflatoxin (0, 25 and 50 ppb) and two dietary cinnamon essential oil (0 and 1 percent) inclusion levels with three respective replicates. The experiment lasted for 60 days. At the end of the experiment random samples were taken to study the aforementioned indices. Hematocrit, red blood cell count and hemoglobin concentration were positively affected by dietary supplementation of cinnamon essential oil (P

A completely randomized experimental design in triplicates was conducted to evaluate the effects of different levels of nitrogen with the constant level of carbon and phosphorous on production of warm water fish in Chapakrod fish farm in Joybar. The treatments were use of three levels of C: N: P, respectively, 1: 5.5: 88.6 (T1) 1: 7.5: 88.6 (T2) and 1: 9.5: 6.88 (T3). The mixed chemical fertilizers and organic manures consisted of chicken, cattle feces, vermi-compost, phosphate and urea mixed together to get different levels of CNP. The effect of different concentrations of nitrogen on phytoplankton abundance and chlorophyll, were investigated as well. At the end of experiment, the highest number of phytoplankton, chlorophyll, relative growth indices were significantly different (P