Comparative toxicity of silver nanoparticle and ionic silver in juvenile common carp (Cyprinus carpio): Accumulation, physiology and histopathology.

Many studies have investigated the potential negative effects of silver on aquatic organisms, but most focused on short-term exposure in few species. Moreover, there are many uncertainties about differences in potential toxicity mechanisms and adverse effects of silver nanoparticles (AgNPs) and ionic form of silver (AgNO3). We investigated chronic effects of AgNPs and AgNO3 on the juvenile common carp (Cyprinus carpio). AgNPs and AgNO3 accumulated in the liver, gill and intestine, respectively and highest was related to AgNPs. Our results indicated, silver uptake was accompanied with histological alteration in the target organs such that different tissue lesions were observed in exposed groups. Superoxide dismutase (SOD), catalase (CAT) and lactate dehydrogenase (LDH) activity and also hsp70, ghrelin and IGF-1 genes expression were induced in both forms. After 7 days, highest hsp70 gene expression was observed in AgNO3 treatment and highest ghrelin and IGF-1 gene expression was observed in AgNPs treatment. The results revealed that adverse effects of AgNPs on different aspects of the health of juvenile common carp, may not be solely a result of particle dissolution. In addition, the main toxic mechanism of AgNPs was probably related to the accumulation of silver followed by the molecular and oxidative stress response.

Effect of dietary chitosan on growth performance, hematological parameters, intestinal histology and stress resistance of Caspian kutum (Rutilus frisii kutum Kamenskii, 1901) fingerlings.

This study was conducted to investigate the effects of dietary chitosan on growth performance, hematological parameters, intestinal histology, stress resistance and body composition in the Caspian kutum (Rutilus frisii kutum, Kamenskii, 1901) fingerlings. Fish (1.7 ± 0.15 g) were fed diets containing chitosan at different levels (0, 0.25, 0.5, 1 and 2 g kg(-1) diet) for a period of 60 days. Results showed that the feed conversion ratio significantly decreased in fish fed diet containing 1 g kg(-1) of chitosan compared to the other groups (P < 0.05), but there were no significant differences between treatments in terms of specific growth rate and condition factor (P > 0.05). Leukocyte increased in fish fed diet containing 2 g kg(-1) of chitosan compared to the other groups (P < 0.05). Lymphocytes, eosinophils and neutrophils did not significantly change among dietary treatments (P > 0.05). Also, the chitosan supplementation did not affect the whole-fish body composition (P > 0.05). Light microscopy demonstrated that the intestinal villus length increased in fish fed diet containing 1 g kg(-1) of chitosan compared to control group (P < 0.05). While 11 and 13 ‰ salinity and 30 °C thermal stress had no effect, 1 g kg(-1) of chitosan (P < 0.05) showed highest survival rate (70 %) in 34 °C thermal stress. The results showed that chitosan in the diet of the Caspian kutum fingerlings could improve feed conversion ratio, the nonspecific defense mechanisms and resistance to some of the environmental stresses.

Effects of diets containing genistein and diadzein in a long-term study on sex steroid dynamics of goldfish (Carassius auratus).

The effect of long-term exposure of goldfish to dietary genistein and diadzein on the concentrations of plasma sex steroids (testosterone (T), 17ß-estradiol (E2)) and the gonadosomatic index (GSI) was assessed. The study was conducted on four groups for a period of 2 years, from the age of 20 weeks to first spawning. Four doses of genistein and diadzein were applied in the feed: genistein: 0 µg/g, diadzein: 0 µg/g (control group); genistein: 24.26 µg/g, diadzein: 21.7 µg/g (diet 1); genistein: 51.55 µg/g, diadzein: 46.13 µg/g (diet 2); and genistein: 75.83 µg/g, diadzein: 67.82 µg/g (diet 3). Throughout the experiment, there were no significant dose- or time-related effects of genistein and diadzein contents on the T level in both sexes. Furthermore, at the highest genistein and diadzein contents, there was an elevating plasma concentration of E2 at all sampling points (p < 0.05) and a time-related effect occurred (p < 0.05). Although the E2 concentrations in the plasma of female, throughout the experiment, were higher than in males, at the last sampling, the plasma concentrations of E2 reduced among females and became lower than that in males. The effects of isoflavone content were found on GSI of females at the fourth and fifth sampling among the treatments. Isoflavone contents also affect GSI of males at the second, fourth and the last sampling. Our findings suggest that overall genistein and diadzein exposure in early life stages can cause alterations in the reproductive organs and influence sex steroidogenesis.

Effect of copper sulfate on the survival and growth performance of Caspian Sea kutum, Rutilus frisii kutum.

The aim of present study was to determine the LC50/96 h value of copper sulfate and determine the growth performance of Caspian Sea kutum) Rutilus frisii kutum (fingerlings during 60-days sub-lethal copper (Cu). After acclimation period to two weeks, for determine the LC50/96 h value, total of 27 aquarium with a capacity of 60 L each stocked with 10 fishes an aquarium. Tunney four aquarium and 8 concentrations of (Cu) composed the 24 treatments while 3 other aquaria were used as control. For each treatment, three replications were conducted. And experiment to determine the growth performance fish were transferred into fiberglass aquaria of 200 L water capacity for growth trials. The treated fish were kept in the aquarium containing sub-lethal concentrations of Cu (0.11 and 0.23 mg L(-1)) and affected to grow for 60 days, while control fish were placed in metal free water. The results indicated that median lethal concentrations (LC50) of copper to Caspian Sea kutum for 96 h exposure was 2.310 ppm. The chronic sub-lethal water-borne Cu exposure to the fish exerted that fish had significantly decreased final body weight in comparison to control group. The copper sulfate also had significant negative effects on specific growth rate (SGR) and feed conversion efficiency (FCE) in comparison to those fed the control group. The feed conversion ratio (FCR) and condition factor (CF) were significantly increased in comparison with the control group (P < 0.05). Also survival rate in experimental treatments in comparison with control group, was significantly decreased (P < 0.05). The treated fish exhibited significantly lower body weight and length gains than that of control. The increments of fish weights, fork and total lengths, condition factor, feed intake and condition factor of treated and control fish varied significantly during study period. Hence, concluded that copper sulfate is toxic for Caspian sea kutum (Rutilus frisii kutum).

Study the seasonal steroid hormones of common carp in Caspian Sea, Iran.

In this investigation, serum steroid hormones such as testosterone (T), 17ß-estradiol (E2) and progesterone (P) in 12 female of the migratory population of Common carp (Cyprinus carpio) in southeast of Caspian Sea during a year from May 2011 to May 2012 were studied. The results of present study revealed that changes in levels of steroid hormones, (E2) and (T) were closely correlated to ovarian development. There was significant difference in level of 17 ß- estradiol between autumn and winter seasons that the highest of 17-ß estradiol level was observed in autumn season. In the case of progesterone hormone, higher levels was recorded in summer season and there was significant difference between summer and spring seasons and lower level of testosterone was observed in spring season.

Effects of acidic water in combination with aluminum on swimming behavior and survival of yolk-sac larval in Goldfish (Carassius auratus gibelio).

Yolk-sac fry of Goldfish (Carassius auratus gibelio) were exposed to various concentrations of Al and pH for 3, 7 and 10 days. In this study number of dead fish, total length of larvae, yolk sac length, swimming activity, the number of gill cover movements and the number of heart beat was measured. The lowest and highest number of gill cover movements belong to the waters containing 50 mg L-1 of aluminum, pH 5.25 and acidic waters with pH 6.7 respectively. There was no significant difference in the number of heartbeat between control group and larvae exposure to acidic waters with pH 6.7 and waters containing 150 mgL-1 of aluminum and the highest number of heartbeat belong to these larvae than other experiment doses. The larval of Goldfish in the all experiment doses lost their swimming ability after 3 days. The highest number of swimming larvae and also lowest number of non-swimming larvae significantly belong to control group compared to other experiment doses (p < 0.05). The larval in the control group only were maintained their swimming activity after 7 and 10 days and in the all experiment treatments lost their swimming ability. There was significant difference in the number of dead larvae and the number of non-swimming larvae between control group and larvae exposure to acidic waters and waters containing 300 mgL-1 of aluminum and pH 4.75 (p < 0.05) and lowest number of non-swimming larvae was observed in the control group. Also the highest of yolk sac length belong to the waters containing 600 mgL-1 of aluminum and pH 4.75. The larvae of Goldfish were not survived in the waters containing 300 and 600 mgL-1 of aluminum and waters with low acidity after 7 days.

Relationship between biological characteristics of eggs and female brood stocks of Persian sturgeon Acipenser persicus: a comparison with other fish species.

We have determined a number of biological characteristics of the Persian sturgeon egg (including diameter, surface-to-volume ratio, yolk sphere and perivitelline space) and of female brood stocks (including age, length, weight, condition and absolute fecundity) in 420 specimens of the migratory population of Acipenser persicus in Gorgan bay of Iran from 2001 to 2004. In the hydrated egg, the average egg diameter, yolk diameter, surface-to-volume ratio and yolk sphere-to-perivitelline space ratio values were: 3.64 +/- 0.17 mm, 3.26 +/- 0.25 mm, 1.65 +/- 0.08 and 0.75 +/- 0.01, respectively. In this chondrostean species, the egg surface and volume were found to increase with increasing egg diameter, but the egg surface-to-volume ratio decreased. In Persian sturgeon, the surface-to-volume ratio and yolk sphere-to-perivitelline space ratio is very high; therefore, the metabolic rate is low and female spawning occurs in low-temperature waters. The statistical Pearson correlation between egg diameter relative to a number of brood stock characteristics, including fork length (r = 0.059), weight (r = 0.140), age (r = 0.081) and absolute fecundity (r = 0.095), were not significantly different (P > 0.05). An extensive comparison of these results with data published on other fish species is presented and discussed.