JOURNAL OF FISHERIES SCIENCE AND TECHNOLOGY (JFST)
Year:2016 | Volume:5 | Issue:1|Papers Count:10

In this study the effect of three dietary treatments including; two concentrations (106 and 107 cells per ml) of the freshwater alga Chlorella vulgaris and one treatment of baker's yeast, Saccharomyces cerevisiae) on growth, protein and total and free amino acid composition of freshwater rotifer Brachionus calyciflorus were studied. Results showed that rotifers fed with high concentration of algae (107cell/ml) had significantly higher growth rate (0.56±0.03) than other treatments. Maximum density of rotifers fed high concentration (1790±10.7 ind/ml) significantly was higher than low concentration (525±41.1 ind./ml) and baker's yeast +oil treatments (115±2.1 ind/ml). The crud protein of rotifers fed yeast was significantly higher than rotifers fed with low density of algae (p<0.05). Total amino acids of rotifers fed yeast, low concentration and high concentration of algae were obtained 250.66±16, 112.15±10 and 198.82±14 mg/ g of sample, respectively that there were significant difference between them (p<0.05). The highest and lowest amounts of free amino acids were observed in rotifers fed yeast (8.77±1.1) and low concentration of algae (4.04±0.3), respectively (p<0.05). Based on this study it can be concluded that rotifers fed with algae showed a higher growth rate compared with those fed the yeast, although protein and free amino acids in rotifers fed yeast were higher in compared algae treatments. In addition, treatment with high concentrations of algae, amino acids showed a relative increase in the body.

Silver nanoparticles (AgNPs) are widely used in consumer products mainly due to their antimicrobial action. The rapid increase in the use of nanoparticles has driven more attention to their possible Eco toxicological effects. In this study: first, acute effects of colloidal AgNPs during embryonic stage of Persian sturgeon and Starry sturgeon were investigated and then in Starry sturgeon, their short-term effects during early life stages (before active feeding commences) were analyzed. Based on the obtained results from the acute toxicity tests, AgNPs induced a dose-dependent toxicity in both species during early life stages. The short-term toxicity test was performed using 0, 0.025, 0.05 and 0.1 mg/l of colloidal AgNPs. Silver accumulation in larvae exposed to 0.1 mg/l AgNPs was recorded significantly higher than the control treatment (P<0.05). However, the obtained survival rate data did not indicate any significant differences among treatments.

The aim of this study was to assess the effects of triploidy induction on survival, growth performance, body composition and fatty acid profiles in rainbow trout. Eight female (1600±246 g) and 6 male (1393±186 g) of fouryear rainbow trout broodstock were selected and stripped. Heat shock treatment achieved 10 min after fertilization, for 10 min and in 28oC water bath. Based on red blood cell analysis, the overall triploidization success level was 87.1±1%.The survival rate from fertilization to eyed stage in triploid group (86.31±1.21%) was significantly (p<0.05) lower than that of diploid group (92.12±1.59%). The survival rate from eyed stage to hatching in triploids (94.04±1.33%) was significantly (p<0.05) lower than that of diploids (98.10±0.45%). Growth performance (initial and final weight, weight gain, specific growth rate and condition factor) was significantly higher in diploids as compared to triploids (p<0.05) after 38 days of rearing. Proximate compositions of fish including protein, fat and ash were not affected by triploidization, but triploids showed higher moisture content compared to that of the diploids. Moreover, the results showed that the levels of saturated fatty acids increased and the levels of unsaturated fatty acids decreased as an effect of triploidy induction.

In this study surimi was produced from big head (Hypophtalmichthys nobilis) carp and the effects of three independent factors including microbial transglutaminase (0.5%, 0.75% and 1%), salt (0%, 1.25% and 2.5%) and temperature (35oC, 40oC and 45oC), were examined on textural properties and color parameters of produced surimi was examined. The results showed that enzyme concentration of 0.5 % and 1.25% of salt at 45oC temperature were as optimum treatment, thereby, reducing the salt percentage from 2.5% to 1.25% without significant reduction in textural properties such as Hardness (resistance of food at the first bitting of the food), Cohesiveness (maintaining the strength of the food during chewing) and Springiness (ability of foos to recovery of its origin shape and size at the first biting). The increasing of the amount of enzyme also resulted in reduction of WHC, significantly (p<0.05). Moreover, when the enzyme and salt were used at low concentrations, the more whiteness and lightness of surimi gel wre produced. Simultaneous effect of salt increasing and setting temperature reduction, resulted in significant higher redness (a*) (p<0.05). Besides, the effect of enzyme alone on yellow factor (b*) was not significant, whereas the simultaneous effect of increasing in enzyme and temperature resulted higher b* factor (p<0.05).

The response surface methodology was employed to optimize the effects of pH, temperature (oC), time (min) and the ratio of enzyme to substrate (% of substrate) on the hydrolysis process of cuttlefish muscle by alcalase. Central composite rotatable design with 5 levels and 4 factors and a=2 was used for the optimization of the process to gain the highest degree of hydrolysis. pH, temperature, time, enzyme concentration, interaction of temperature-enzyme concentration, square of pH, temperature, time and enzyme concentration had significant effects on the process. The R2=0.95, lack of fit<0.05 and adeq-Precision of 14.16 for the model showed that the model could explain the variability within the range of values. The optimum condition for 42.0117 % of degree of hydrolysis was determined by Design Expert as pH 8.19, temperature 50.23, time 129.62 and enzyme2.15%.

The effect of adding digestrom P.E.P at 0, 1, 2 and 4% of feed on the growth and hematology of juveniles (159.5±0.23 g) beluga, Huso huso, was investigated during 70 days feeding trial. Significantly higher average daily growth, specific growth rate and protein performance were observed in fish fed diet containing 2% digestrom P.E.P (p<0.05), but the condition factor, hepatosomatic index and feed conversion ratio didn’t significantly differ among treatments (p>0.05). No significant difference were observed in the number of red blood cells, hematocrit, MCV, MCH, MCHC, lymphocytes, monocytes among treatments (p>0.05), but the number of white blood cells and neutrophils in the 2% treatment was significantly higher than other treatments (p<0.05). Fish carcass analysis revealed a significantly higher protein content in the 2% treatment than the control group (p<0.05), but the difference was not significant in fat, ash and moisture contents (p>0.05). Based on the results, the digestrom P.E.P at 2% of feed can enhance growth and stimulates the immune system of the juvenile beluga.

Extracted polysaccharides from green seaweeds are heterogeneous in structural and molecular properties. Basically, sulfated polysaccharides from green seaweeds contain various amounts of rhamnose (16.5-45.0%), xylose (2.1-12.0%), glucose (0.5-6.4%) and sulfate (16.0-23.2%), and their building blocks are chiefly comprised of b-D-GlcpA-(1®4)a-L-Rhap3s. Molecular weight of sulfated polysaccharides varies from 93.4´103 to 1690´103 g/mol. The biological effects of seaweed sulfated polysaccharides are immunomodulation, cancer cell growth suppression, antioxidation, antihyperlipidemic, antiviral and anticoagulation. As the chemical structure and molecular properties of sulfated polysaccharides differ from one seaweed species to another, the biological properties varies subsequently. Overall, given the fact that highly variable marine environment can significantly incorporate into the existing discrepancies of sulfated polysaccharide structures due to seaweed phylogenetic differences, executing more comprehensive studies on various species is necessary to have a better understanding of their function and future applications.

Solvent extraction and taguchi method were used to optimize conditions for the antioxidant activity of Azolla fern extracts. The independent processing variables were ethanol concentration, extraction time and solid to solvent ratio. Ethanol concentration and solvent to solid ratio significantly affected antioxidant activity measured by the total phenol content (p<0.05). whereas the extraction time did not significantly affect the activity (p>0.05). Antioxidant activity of the extracts, determined by the total phenolic content, varied from 5.77 to 16.42 mg acid gallic equivalents/g of dry sample. DPPH scavenging activity percentage ranged from %20.51 to %93.71. Ethanol concentration of %50 and sample to solvent ratio of 1 to 15 were optimal for the highest antioxidant activities measured by the TPC assay and the DPPH method. The optimal extraction time was 48h. The result show that azolla fern is suitable for antioxidant extraction.

The molecular characteristics of Yersinia ruckeri such as total proteins (TP), outer membrane proteins OMP) and lipopolysaccharides (LPS) in 34 isolates from rainbow trout farms in Tehran, Mazandaran and Zanjan provinces were determined, using SDS-PAGE method. The molecular weight (MW) for TP of all bacterial isolates was mostly less than 100 KD with a banding density in range 28 to 100 KD. Also, protein pattern of OMP consisted of three major bands with MW of 28-35 KD (two bands) and 10-17 KD (one band) plus some minor bands with MW of 48-75 KD and 17-28 KD. In addition, the LPS pattern of all bacterial isolates were less than 130 KD with the most band density in range 28-100 KD. These results show that the banding profile of TP, OMP and LPS of all isolates of Y. ruckeri were identical, demonstrating minimum heterogeneity among Iranian isolates of Y. ruckeri. Therefore, it is feasible for the formulation of a monovalent vaccine to yersiniosis in future.

The effect of essential oil (EO) from Carum copticum at concentrations of 0 (control), 0.5%, 0.75% and 1% on Staphylococcus aureus growth and gene expression of enterotoxins (SE) A and C in surimi from kilka (Clupeonella cultriventris caspia) was determined during 0, 5, 10, 15 and 20 days of refrigeration storage (4oC). The main compounds of EO were thymol (36.4%), p-cymene (31.4%) and g-terpinen (21.73%). Minimum inhibitory concentration and maximum tolerable concentration of EO against in S. aureus in broth medium were 0.06% and 0.015%, respectively. The growth rate significantly differ between S.aureus population in control (11.31 log CFU/g) and EO-treated samples, 9.76, 7.21 and 6.06 log CFU/g in samples containing 0.5%, 0.75% and 1%, respectively. The highest inhibitory activity against gene transcription of entertoxins was observed at 1% EO; also, the inhibitory effect of EO concentrations against expression of enterotoxin C was higher than enterotoxin A., as enterotoxin A expression was 4.5 and 8.23 fold lower than control at days 5 and 20, and enterotoxin C expression, at days 5 and 20, decreased 5.11 and 8.94 fold compared to control. The results of this study showed that EO from C. copticum is an effective component in reducing bacterial growth rate and staphylococcal enterotoxins production in kilka surimi.