Effect of dietary phospholipid sources and levels on growth performance,enzymes activity,cholecystokinin and lipoprotein fractions of rainbow trout (Oncorhynchus mykiss) fry

This study was conducted to evaluate the effect of soybean lecithin (SBL) and chicken egg lecithin (EGL) on growth performance; pancreatic and intestine enzymes, cholecystokinin (CCK) and lipoprotein fractions of rainbow trout, Oncorhynchus mykiss (Walbaum) fry. Seven isonitrogenic and isolipidic diets were prepared by replacing 0 (as a control), 2%, 4% and 6% soybean and chicken egg lecithin instead of soybean oil in diets. Trout fry with initial average weight of 120 ± 4.08 mg, were randomly distributed in 21 90 L tanks. Triplicate groups (165 fish for each tank) of fry were fed each diet to visual satiation at six meals per day for 40 days. Dietary supplements of 2% and 4% chicken egg lecithin led to increase in fry final weight, weight gain and specific growth rate suggesting that moderate PL levels are needed during this stage of rainbow trout. Also 2% chicken egg lecithin caused significantly higher activity of amylase, lipase, phospholipase A₂, alkaline phosphatase (AP), aminopeptidase‐N (AN) and lower activity of leucine alanine peptidase (leu‐ala) in the digestive tract of fry than those in control group. Furthermore, fry fed 2% chicken egg lecithin had a higher ratio of AN/leu‐ala and AP/leu‐ala than that in the control group. Chicken egg lecithin increased significantly cholecystokinin (CCK) and chylomicron fractions of fry compared to control group. It is noteworthy that soybean lecithin had moderate effect on final growth, weight gain and specific growth rate of fry and induced significantly higher activity of amylase, lipase, phospholipase A₂ and secretion of CCK compared to control group. The results of this study indicate that dietary supplementation 2% chicken egg lecithin indirectly through some biochemical parameters improves growth performance of rainbow trout fry.     

Analysis of genetic and virulence variability of Stemphylium lycopersici associated with leaf spot of vegetable crops

Stemphylium lycopersici (Enjoji) W. Yamam was initially described from tomato and has been reported to infect different hosts worldwide. Sequence analyses of the internal transcribed spacer (ITS) regions 1 and 2, including 5.8S rDNA (ITS-5.8S rDNA) and glyceraldehyde-3-phosphate dehydrogenase (gpd) gene, random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR), as well as virulence studies were conducted to analyze 46?S. lycopersici isolates. Stemphylium lycopersici isolates used in this study were obtained from diseased tomato (Solanum lycopersicum L.), eggplant (Solanum melongena L.), pepper (Capsicum annuum L.) and lettuce (Lactuca sativa L.) from major vegetable growing regions of Malaysia, including the three states of Pahang, Johor and Selangor between 2011 and 2012. Phylogenetic analysis of a combined dataset of the ITS-5.8S rDNA and gpd regions indicated that all isolates were clustered in the sub-cluster that comprised S. lycopersici, and were distinguished from other Stemphylium species. Cluster analyses using the UPGMA method for both RAPD and ISSR markers grouped S. lycopersici isolates into three main clusters with similarity index values of 67 and 68 %. The genetic diversity data confirmed that isolates of S. lycopersici are in concordance to host plants, and not geographical origin of the isolates. All S. lycopersici isolates were pathogenic on their original host plants and showed leaf spot symptoms; however, virulence variability was observed among the isolates. In cross-inoculation assays, the representative isolates were able to cause leaf spot symptoms on eggplant, pepper, lettuce and tomato, but not on cabbage.     

Tunable functional properties on polyester fabric using simultaneous green reduction of graphene oxide and silver nitrate

Here, a novel method is introduced to create tunable properties on the polyester fabric through diverse chemical modifications. The polyester fabric was primarily modified with NaOH or ethylenediamine to enhance the surface activity. This will produce diverse chemical groups on the polyester fabric surface including carboxylate, hydroxyl and amine groups. The fabric was treated with grahene oxide through exhaustion method. The silver nitrate was then added and simultaneously reduced with grapheme oxide using ascorbic acid and ammonia to produce reduced graphen oxide/silver nanocomposites (rGO/Ag) on the fabric surface. The synthesized nanocomposites were characterized by TEM and Raman spectra. The presence and uniform distribution of the nanocomposites on the fabric surface was also confirmed by SEM images and EDX patterns. The electrical resistivity was varied on the raw and modified polyester fabric due to the diverse formation of the graphene nanosheets network on the fabric surface. More Ag particles were formed on the surface of the alkali hydrolyzed polyester whereas more graphene nanosheets deposited on the aminolyzed polyester fabric. Also the hydrolyzed polyester fabric exhibited higher antibacterial properties with the lowest silver nitrate in the processing solution. The aminolyzed fabric showed a lower electrical resistance than the hydrolyzed and raw fabrics with the same amount of GO in the procedure bath. The aminolyzed polyester fabric indicated higher affinity towards GO produced higher antibacterial properties before reduction and without silver nitrate however lower electrical resistance obtained after reduction comparing with other samples.     

Mercury and methyl mercury concentration in sediment,benthic, Barbus Grypus and pelagic,Barbus esocinus fish species,from Musa estuary,Iran

The concentrations of mercury (Hg) and methyl mercury (MeHg) in sediment and tissues of Barbus grypus and Barbus esocinus fish species from Musa estuary, north part of the Persian Gulf, were measured. The order of Hg and MeHg concentrations in the sediment and tissues of the fish species was as follows: liver > gill > muscle > sediment. In the tissues of two fish species, the Hg and MeHg concentrations were highest in liver whereas lowest in the muscle. In the sediment, mean concentrations of Hg and MeHg were 0.83 and 0.437 µg g^?1. Mean concentrations of Hg and MeHg in B. grypus were 1.2–0.624 µg g^?1 and in all tissues of B. esocinus were 0.75 and 0.421 µg g^?1. Significant correlation between heavy metal concentration in sediment and fish may be related to high variability of heavy metal in the sediment.     

The role of polychaete Nereis diversicolor in bioremediation of wastewater and its growth performance and fatty acid composition in an integrated culture system with Huso huso (Linnaeus, 1758)

This study was undertaken to evaluate the role of polychaete Nereis diversicolor in bioremediation of waste water and its growth performance and fatty acid composition in an integrated culture system with great sturgeon, Huso huso. Three treatments consisting of N. diversicolor fed with H. huso waste (FNW), N. diversicolor fed with fish feed waste (NW), and fish waste without the worm (FW) were considered at water temperature of 23°C for 8 weeks. The obtained results demonstrated that N. diversicolor in the flow‐through system could grow via feeding with the fish waste water. The pure production and survival rate of harvested Nereis in NW treatment were significantly higher than those of FNW treatment (p < .05). However, no significant difference was observed in specific growth rate and weight gain between these two treatments (p > .05). The highest removal efficiency of waste water including total nitrogen (56%), total phosphorus (53%), NO₂‐N (91%), NH₃‐N (35%)_, PO₄‐P (47%), BOD₅ (60%) were seen in FNW treatment. Also, the highest additional efficiency of NO₃‐N occurred in FW (37%) treatment. Certain fatty acids specifically 20:5 ω3 (eicosapentaenoic acid [EPA]) and 22:6 ω6 (docosahexaenoic acid [DHA]) were also abundant in Nereis, and analysis revealed some differences due to the diet. These results demonstrated that the promotion of growth by cultured Nereis can enhance the decomposition rate of organic matter in enriched sediment and minimize negative effects in fish farms. These results also suggest that the use of N. diversicolor is an excellent potential candidate for an integrated aquaculture and nutrient recycling including the removal of organic wastes.     

Determination of grapefruit (Citrus paradisi) peel extract bio‐active substances and its application in Caspian white fish (Rutilus frisii kutum) diet: Growth,haemato‐biochemical parameters and intestinal morphology

In this study, total phenolic and flavonoid contents of grapefruit peel extract (GPE) were equal to 117.3 ± 0.3 µg of gallic acid/mg and 39.30 ± 0.1 µg of quercetin/mg respectively. Caspian white fish (n = 180, 4 ± 0.9 g body weight) was fed with supplemented diets, including 0, 6.25, 12.5 and 25 mg of GPE/kg for 60 days at 25 ± 1°C. The growth performance was markedly improved in fish fed with 25 mg/kg of GPE compared to others (p < 0.05). Moreover, fish fed with 25 mg/kg of GPE showed a significant increase in red blood cell (2.65·10⁶ cell/mm³), white blood cell (17.75·10³ cell/mm³), packed cell volume (48%) and haemoglobin concentrations (8.75 g/dl) compared to the control (p < 0.05). However, the highest alanine aminotransferase (140 U/L), alanine transaminase (14.5 U/L), and alkaline phosphatase (18.5 U/L) were observed in control group. Morphological analysis of intestine revealed the highest amount of villus width (8.4 µM), height (32.86 µM) and surface area (342.7 µM²) in fish fed with 25 mg/kg of GPE (p < 0.05). In conclusion, supplementing feed with GPE at 25 g/kg can improve growth performance and haemato‐biochemical parameters of Caspian white fish fry.     

The antibacterial and antibiofilm activity of sea anemone (Stichodactyla haddoni) against antibiotic-resistant bacteria and characterization of bioactive metabolites

International Aquatic Research - Sea anemones produce many biologically active compounds including neurotoxins, pore-forming toxins, phospholipases and proteinase inhibitors. The Persian Gulf is an...     

The effect of supplementing diets with extracts derived from three different species of macroalgae on growth,thermal stress resistance,antioxidant enzyme activities and skin colour of electric yellow cichlid (Labidochromis caeruleus)

The purpose of this study was to evaluate the growth, thermal stress resistance, antioxidant enzyme activities and skin colour of Labidochromis caeruleus (electric yellow cichlid) fed the diets supplemented with extracts derived from brown macroalga Sargassum boveanum, red macroalga Gracilaria persica and green macroalga Entromorpha intestinalis. One hundred and forty‐four fish were randomly distributed into 12 tanks and subjected to cold‐shock stress after 8 weeks of feeding the diets containing 1,000 mg extracts of macroalgae. Supplementation of fish diet with algal extracts led to improved growth performance (including higher final weight and weight gain) when compared to the control group, which was fed the non‐supplemented diet. The survival rate after cold‐shock stress was significantly higher in those fish fed the diets containing macroalgal extracts, especially E. intestinalis extract (75%). The superoxide dismutase activity in all dietary treatments was significantly lower than control, whereas no significant difference in the activities of catalase and lysozyme was observed among treatments. In addition, inclusion of macroalgal extracts in the diet resulted in higher a* (redness) and b* (yellowness) values compared to the control group. These results suggest that macroalgal extracts, especially E. intestinalis extract, can be used as feed additive for increasing antioxidants capacities as well as enhancing pigmentation in electric yellow cichlid.     

Effect of different sources and forms of dietary carbohydrates on growth performance,body indices and lipogenesis activity of striped catfish Pangasianodon hypophthalmus fingerlings

A 12‐week feeding trial was conducted to determine a suitable carbohydrate source and form for Pangasianodon hypophthalmus. Ten isoenergetic, isonitrogenous and isolipidic diets, including five carbohydrate sources (dextrin, potato starch, wheat starch, corn starch and sago starch) and two carbohydrate forms (raw and cooked), were formulated. Results showed that specific growth rate, weight gain percentage, whole‐body lipid and 6‐phosphogluconate dehydrogenase enzyme activity of fish fed with cooked carbohydrates were significantly lower (p < .05) than those fed with raw carbohydrates (p < .05). Similarly, the fatty acid synthase enzyme activity of fish fed with the cooked form of carbohydrates was significantly lower (p < .05) than that fed with the raw form of carbohydrates except fish fed with cooked potato starch. The blood glucose level and malic enzyme activity of fish fed with cooked carbohydrate were significantly (p < .05) higher than those fed with raw carbohydrate. In summary, this study showed that cooked starch is an unsuitable dietary carbohydrate form for Pangasianodon hypophthalmus fingerlings. The raw forms of dextrin starch and potato are suitable dietary carbohydrate sources for further scientific studies on the carbohydrate utilization of P. hypophthalmus.     

Effects of rearing density on growth,fatty acid profile and bioremediation ability of polychaete Nereis diversicolor in an integrated aquaculture system with rainbow trout (Oncorhynchus mykiss)

The objective of this study was to assess the effects of rearing density on the growth and fatty acid profile of Nereis diversicolor and on its capability to bioremediate wastewater in an integrated culture system with rainbow trout (Oncorhynchus mykiss). To this end, a batch of juvenile N. diversicolor (0.03 ± 0.01 mg) was assigned into four different densities (T₁ = 250, T₂ = 500, T₃ = 1,000, T₄ = 2,000, besides T₀ = with no worm) in three replicates. The worm groups were fed with solid waste that was supplied from tanks containing rainbow trout (107.17 ± 13.5 g; 1.39 ± 0.18 kg/m³). During the experiment (60 days), the water temperature was 17.71 ± 0.6°C. The results revealed that SR%, SGR% and WG% of N. diversicolor in T₁ were significantly higher than those of T₂, T₃ and T₄. Both FER rate and biomass gain in T₄ were significantly higher than those in the other groups. The highest removal rate of NO₂‐N (73.72%), NH₃‐N (65.70%), PO₄‐P (59.32%), BOD₅ (69.60%) and TSS (82.33%) were observed in T₄. The major fatty acids presents were palmitic acid, oleic acid, linoleic acid, stearic acid and alpha‐linolenic acid in all worm‐treated groups, with no difference observed in the concentration of these fatty acids among them. Taken together, these findings suggest that organic wastes from rainbow trout farms could be recycled to achieve a sustainable aquaculture goal, and demonstrate that a high percentage of fatty acids in fish feed is not absorbed by rainbow trout but is done by N. diversicolor.