Preliminary study on semi-closed incubator efficiency for hatching Persian sturgeon (Acipenser persicus) eggs

The present study investigated the efficiency of semi-closed incubator for hatching the Persian Sturgeon (Acipenser persicus) eggs. The incubator was basically designed according to Vase equipped with collector vessel, recirculation pump and aerator. 50% of water was changed every day. Persian Sturgeon (50 g) fertilized eggs samples were stocked in the incubators with three replica. Water flow rate was set not to harm the eggs and only circulating the eggs. The mortality of embryos and larvae at gasterula stage, formation of S-type heart stage, before hatching and hatching percent were recorded. Our result showed that the incubated circulated eggs completely and the probability of fungal infections was lower than that of flow through incubators. Since water used in semi-closed incubator is far less than that of flow through systems, that semi-closed incubator may be a proper alternative for flow-through incubated systems in future

Hydrocortisone treatment may enhance survival and stocking of Beluga sturgeon (Huso huso Linnaeus, 1758) in estuaries of the Caspian Sea

Beluga sturgeon (Huso huso Linnaeus, 1758) fingerlings are released into the Caspian Sea for recruiting and enhancing commercial and recreational fishing purposes. These fingerlings are reared in fresh water, but released to the estuaries that may be caused mortalities due to acute osmotic stress. In this study, the fingerlings in whole (in vivo) or their gill tissue (in vitro) were exposed to three different levels of ‘the stress hormone’ cortisol (3, 5, 7 mg L-1 hydrocortisone sodium phosphate) for 24 hrs. The effects of treatments on blood cortisol levels and the size and numbers of gill chloride cells were monitored. In each case, hormonal treatment significantly increased blood cortisol levels and also the number but decreased the size of the chloride cells. We conclude that bathing in hydrocortisone could promote the survival rate of the fingerlings in brackish water and may be have a positive effect on their osmoregulation potentiality

Morphometric analysis of olfactory organ and telencephalon in maturing and mature migrants of Caspian lamprey (Caspiomyzon wagneri, Kessler 1870)

This study was conducted to provide a detailed information about changes of the olfactory organ and telencephalon morphology in spring and fall spawning run maturing and mature Caspian lamprey, Caspiomyzon wagneri, in the Shirud River, Sothern Caspian Sea basin, Iran. A total of 71 maturing and mature fish were collected during their spawning migration. The results showed that the thickness of the olfactory epithelium and the density of ciliated olfactory receptor cells (ORC) were lower in mature migrants. In addition, the nasal cavity, relative weight of olfactory organ and relative telecephalon area in mature migrants were larger indicating its more sensitivity to external queues. Based on the results, the olfactory organ and telencephalon of maturing migrants of Caspian lamprey have not developed completely and needs a period of rest in the river to its full development for spawning

Comparative analysis of milt quality in the cultured and wild stocks of endangered Caspian brown trout, Salmo trutta caspius

The sperm motility characteristics (percentage of motile spermatozoa and duration of motility) and sperm production (spermatocrit, milt volume and sperm concentration) were measured in order to compare the milt quality between cultured and wild stocks of Caspian brown trout, Salmo trutta caspius. Our results showed that cultured brooders produce more dense milt than wild individuals. In contrast, the milt volume, percentage and duration of spermatozoa motility were higher in wild brooders than in cultured individuals. The aim of the present study was to assess the effect of captivity condition on milt quality of cultured males of Caspian brown trout.Keywords: Sperm density, sperm motility, Caspian brown trou

Lysine and leucine deficiencies affect myocytes development and IGF signaling in gilthead sea bream (Sparus aurata)

Optimizing aquaculture production requires better knowledge of growth regulation and improvement in diet formulation. A great effort has been made to replace fish meal for plant protein sources in aquafeeds, making necessary the supplementation of such diets with crystalline amino acids (AA) to cover the nutritional requirements of each species. Lysine and Leucine are limiting essential AA in fish, and it has been demonstrated that supplementation with them improves growth in different species. However, the specific effects of AA deficiencies in myogenesis are completely unknown and have only been studied at the level of hepatic metabolism. It is well-known that the TOR pathway integrates the nutritional and hormonal signals to regulate protein synthesis and cell proliferation, to finally control muscle growth, a process also coordinated by the expression of myogenic regulatory factors (MRFs). This study aimed to provide new information on the impact of Lysine and Leucine deficiencies in gilthead sea bream cultured myocytes examining their development and the response of insulin-like growth factors (IGFs), MRFs, as well as key molecules involved in muscle growth regulation like TOR. Leucine deficiency did not cause significant differences in most of the molecules analyzed, whereas Lysine deficiency appeared crucial in IGFs regulation, decreasing significantly IGF-I, IGF-II and IGF-IRb mRNA levels. This treatment also down-regulated the gene expression of different MRFs, including Myf5, Myogenin and MyoD2. These changes were also corroborated by a significant decrease in proliferation and differentiation markers in the Lysine-deficient treatment. Moreover, both Lysine and Leucine limitation induced a significant down-regulation in FOXO3 gene expression, which deserves further investigation. We believe that these results will be relevant for the production of a species as appreciated for human consumption as it is gilthead sea bream and demonstrates the importance of an adequate level of Lysine in fishmeal diet formulation for optimum growth

Effects of different levels of inorganic supplementation in hydroponic system on growth and hemato-immunological responses of Nile tilapia (Oreochromis niloticus)

The aim of the present study was to investigate the effect of different levels of inorganic supplements in hydroponic system with the water recycle system on some parameters related to the Nile tilapia health status. So, 180 fish weighing 30 ± 3.8 g was divided into 9 experimental units (3 for each treatment). The treatments included diets supplemented with 25% (T2) and 75% (T3) inorganic minerals in hydroponic system. The control group (T1) fed diet with no supplementation. Following 70 days, blood samples were collected from caudal vein of 5 fish. Results indicated significant alterations in hematological and immunological indices in treatments compared to control (p<0.05). Generally, the intestine epithelium development in addition to the enhanced hematological and immune indices indicates the better health status in Nile tilapia following dietary manipulation by inorganic supplementation

Immunolocalization of Insulin-Like Growth Factor-I and its Immunoreactivity during Ovary Developmental Stages of Persian Sturgeon Acipenser Persicus

Objective: Immunohistochemical localization and immunoreactivity of insulin-like growthfactor-I (IGF-I) were investigated during the ovarian developmental stages in Persian sturgeon.In addition, the effects of growth hormone and thyroxine were investigated on IGF-Iimmunoreactivity in vitro.Materials and Methods: Ovarian samples were taken from two brood stocks (caughtfrom the sea and from a river) during their reproductive migration and at three different developmentalstages based on their polarization index (PI). The effects of two hormones onIGF-I immunoreactivity were studied at two ovarian developmental stages (PI > 0.1 andPI < 0.07). In both experiments the immunoperoxidase method was performed in order todetect immunohistochemical localization and immunoreactivity of IGF-I.Results: Immunohistochemical localizations of IGFI were detected in the follicular layers.There was no significant immunoreactivity difference between the two brood stocks,however in the river brood stock IGF-I immunoreactivity was more intense in the ovarieswith PI < 0.07 than of PI > 0.1 (p < 0.05). Growth hormone (10 ng/ml) increased IGF-I immunoreactivityin ovarian samples from the river brood stock when their PI was less than0.07, however thyroxine had not such effect (p < 0.05).Conclusion: Our results showed that IGF-I is present in the ovaries of Persian sturgeonand its reactivity is different among their gonadal development stages. This may supporta role for IGF-I during reproductive physiology in female brood stocks of the Persian sturgeon.Moreover, growth hormone is a potential hormone to increase IGF-I immunoreactivityin the ovaries of this species