This study aimed to determine the effects of sublethal concentrations of ammonia on the pituitary–gonadal axis and gonadal tissue changes in Nile tilapia. Following adaptation, 60 Nile tilapias with an average weight of 200 ± 10 g were divided into 4 × 15 with 3 replications, including control and 3 experimental groups. Fish were exposed to various ammonia concentrations (10

Introduction: Nile tilapia, Oreochromis niloticus is one of the commercially important fish species in many parts of the world. Red algae constitute a widely-used composition of the diet. The purpose of the present study was to replace the red algae on the diet with enzymes and its impact on Nile tilapia gastrointestinal tract. Materials and methods: A total of 120 pieces of tilapia with an average weight of 30 ± 1 g after acclimation for 6 weeks in 100-L aquariums were divided in 4 groups and three replicates (10 fish in each tank) and then fed with basic diet (BioMar Company, France) containing zero, 3%, 6%, and 9% red algae (C, T3%, T6% and T9%). At the end of the rearing period, the fish was anesthetized by clove powder and after dissecting the abdomen, a 0.5-cm tissue samples were removed from the middle of the esophagus, as well as the anterior, middle, and posterior parts of the intestine, then placed in 10% neutral buffered formalin as a fixative solution. After going through the routine steps of tissue preparation, including dehydration with alcohol, clarification with xylol, blocking with paraffin, cutting with a thickness of 4-6 microns with a microtome, and hematoxylin-eosin staining, finally, the evaluation was done with a light microscope. Results: Histological examination in the mid-esophagus, anterior, middle, and posterior parts of the intestine showed that the highest number of mucous cells, the highest thickness of the epithelium and muscle layer, as well as the highest height and thickness of the esophageal villi were observed in the group receiving the diet containing 9% red algae. Also, protease, amylase and lipase enzymes in the treatments had a higher level than in the control group, with the exception that the amount of protease was higher than amylase and lipase. Conclusion: According to the results of the present study, it can be concluded that using red algae in the diet of Nile tilapia exhibited no side effects at the aforementioned levels, even improved tissue metric parameters.

Abstract Background Heavy metals are one of the most important environmental pollutants in marine coastal ecosystems. Cadmium is a heavy metal that enters to marine environments via industrial wastes and oil production activities. Objectives This study were done to determine the toxicity of cadmium to Litopenaeus vannamei and to evaluate the histological changes in gill tissues after exposure to sublethal concentrations of cadmium at different salinities. Methods For this reason, toxicity test was done to determine the lethal concentration (LC50) of cadmium for whiteleg shrimp. According to the calculated LC50 amount, sublethal doses of cadmium were used to determine its histological effects in different salinity during 2 weeks exposing period. Results LC50 of cadmium for 96 h for whiteleg shrimp was 6.56 mg/L. Histological alterations in the gill were observed in L. vannamei after 14 days exposure to different concentrations of cadmium and salinity. Histopathological index was increased in a dose‐dependent manner. Conclusion Our findings showed that doses lower than 2 mg/L have repairable effects on gill structure, but the concentration of 2 mg/L cadmium leaves irreparable and destructive effects on the gill tissue.

Most tilapias are microphytes, but some prefer higher plants. Ammonia is one of the most important toxic compounds of nitrogen, which is a serious problem in the environment and aquaculture industry. In the present study, juvenile Oreochromis niloticus were exposed to 10, 20, and 30% (96h LC50) of ammonia for two weeks, which are equivalent to 0.9, 1.8, and 2.7 mg / l, respectively. After this period, the fish were anesthetized and blood samples were taken from the caudal stalk with a heparin syringe for evaluating blood indicators. The tissue samples were taken 0.5 cm from the liver, fixed in 10% formalin buffer, and after dehydration with alcohol, clarification with xylol, blocking with paraffin, and cutting 4-6 microns thick with microtome were done. Finally, the stained slides were studied with a light microscope. The results showed phenomena such as hyperemia, nuclear hypertrophy, sinusoidal dilatation, increased melanomacrophage centers, nucleus margination, hepatocyte vacuolation, and cell necrosis in the liver. In the studies of blood serum factors with the increase of ammonia, it has been increased in AST, ALT, and ALP compared to the control and other groups. Also, as the ammonia concentration increased, the severity of the lesions also increased. Therefore, ammonia causes changes in the structure and activity of metabolic enzymes of the liver, which must be controlled by creating the appropriate ammonia and management conditions in the aquatic environment.

Paraqut is an important herbicide with widespread use and toxic effects on fish and aquatic ecosystems. Therefore, in the present investigation, an attempt was made to study the toxic and histopathological effects of paraquat on Mugil cephalus. The LC50 value was found to be 1.52 mg/L for 96 hrs. After a week of adaptation 60 Benny fish fingerlings were divided into 4 aquaria; 3 aquaria had paraquat concentrations of 0.38, 0.76 and 1.14 mg/L (respectively 25%, 50% and 75% of LC50) and the fourth aquarium contained control fish. The exposure period lasted for 96 hrs. Epithelial lifting, hyperplasia and hypertrophy, hyperemia, and club-shaped sticky filaments were observed in dill of fish exposed to paraquat. Also, the chloride and mucosal cell density and their space were significantly elevated in some treatments (p<0.05). Thickness of lamella and thickness of filament epithelium increased significantly at 0.76 mg/l. The liver of exposed fish contained nuclear conformation and pyknosis, necrosis, margination, vacuolated cytoplasm, and hemorrhage with more severity in higher concentrations of paraquat. Number of nuclei and size of hepatocytes significantly increased (p<0.05) in 0.76 and 1.14 mg/l. Blood cell infiltration and epidermal lesions were observed in the skin. Intestinal tissue showed edema, lymphocyte infiltration, inflammation and epidermal disruption. Vacuolation and clear holes were the main lesions of paraquat in high concentration in the eye and the brain. Kidney showed abnormality in renal tubules, Glomerole atrophy and bowman dilation. Tubular abnormality and glomeruli diameter showed significant changes (p<0.05). Injury index showed significant injuries in the gill, liver and kidney (p<0.05) but lower changes in the skin. MDA, Urea, and Crateanine, significantly increased (p<0.05) in 0.76 and 1.14 mg/l but GSH significantly decreased (p>0.05). Based on these results it can be concluded that paraquat has toxic effects on M. cephalus.

A 56-day research was carried out to determine the interactive effects of water temperature (WT) and salinity (WS) on physiological responses of yellowfin seabream, Acanthopagrus arabicus (Iwatsuki, 2013) (10.0 +/- 0.2 g). Three salinities (S; 12, 35 and 50 parts per thousand) and four temperatures (T; 16, 23, 30 and 35 degrees C) were selected to design 12 experimental treatments. The husbandry system consisted of thirty-six 300-L cylindrical polyethylene tanks that were filled with 250 L of water. Each treatment had three replicates (tanks) containing 20 fish in each tank. Fish were handfed on a commercial feed (440 g kg(-1) crude protein and 180 g kg(-1) crude fat) twice daily at visual satiation. Five fish from each tank were transferred into an experimental chamber to evaluate their oxygen consumption and ammonia excretion. There was a positive correlation between fish oxygen consumption and WT (r=0.594; p=0.001). In addition, there was a negative relationship between WS and ammonia excretion (AE) (r = -0.865; p=0.029), meanwhile the relationship between WT and AE was positive (r=0.422; P=0.01). Growth parameters were significantly affected by WT, WS and their interactions so that the highest final body was recorded in the highest temperature and salinity treatment. On the other hand, the lowest body weight was observed in the lowest WT (i.e., 16 degrees C) irresponsive to WS. The moisture level in the whole body was affected by WT (p=0.012). The crude lipid in the whole body was influenced by only WS (p=0.04). The ash content in the whole body was profoundly affected by WT (p=0.0001), WS (p=0.0001) and their interaction effect (p=0.04). The energy content of the whole body was only affected by WT (p=0.025). The energy budget of fish was influenced by WT (p=0.0001) and its interaction with WS (p=0.015). In summary, the present findings indicated that the preferred WT for A. arabicus is between 30 to 35 degrees C in brackish water.

Sea urchins have important effects on marine ecosystems such as rocky shores and coral reefs across the world. However, species diversity and molecular phylogeny of most echinoid taxa are poorly known in Iran. In this study, the phylogenetic relationships of one of the most abundant species of the genus Echinometra in the Persian Gulf were examined. Echinoids were collected from the intertidal zone of Qeshm Island and Lengeh Port on March and December 2017. Morphological criteria based on valid identification keys combined with molecular analysis of a fragment of the mitochondrial cytochrome c oxidase subunit I (COI) protein-coding gene were used to delineate Echinometra species. Our analyses showed that all specimens (N = 15) belong to Echinometra sp. EZ. Tree topologies indicated that our individuals from two sampling sites formed a distinct monophyletic clade with E. sp. EZ, demonstrating high support values. This is the first phylogenetic analysis of E. sp. EZ from Iran.

Root canal irrigation plays an important role in debridement and disinfection of the root canal system. The present study aimed to evaluate the efficacy of 17% ethylenediaminetetraacetic acid (EDTA), 2% iodine-potassium iodide (IKI), and 1% and 3% concentrations of sodium hypochlorite (NaOCl) for root canal irrigation in the anterior primary teeth. A total of 60 anterior primary teeth were selected and assigned to 1 of 4 irrigation groups (n = 15): 1, 17% EDTA; 2, 3% NaOCl; 3, 2% IKI; and 4, 1% NaOCl. The root canals in all groups were subsequently irrigated with normal saline following a 30-minute incubation period. The prepared specimens were cut longitudinally and imaged using scanning electron microscopy to evaluate the cleaning efficacy in the coronal, middle, and apical thirds. Data were analyzed using descriptive statistics as well as nonparametric Kruskal-Wallis and Mann-Whitney U tests. Group 2 (3% NaOCl) showed the greatest efficacy for cleaning the entire root canal (P < 0.01). Analysis of the different parts of the root canal revealed that group 2 also demonstrated the greatest efficacy in achieving a clean apical portion (P < 0.01). According to the results of the present study, 3% NaOCl offered a better performance in irrigating the root canals of primary teeth.

The present study attempts to investigate some blood parameters of Otolithes ruber during different seasons in terms of both temperature and pollution. For so doing it uses 10 specimens, for each station and season, collected from 5 polluted stations, including Petrochemical, Ghanam, Zangi, Douragh, Patil, and Sajafi as the control group, away from pollution in Musa Creek. The fish are anesthetized with 1ml of clove extract per liter. Their blood samples are taken immediately from the caudal vein, using a heparinized syringe. Afterwards, the serum is separated in a centrifuge with a speed of 6000 rpm for 2 minutes. The desired factors are measured by the Mindray BS200 auto-analyzer and the total protein level, by Bradford's usual laboratory methods. Results show that AST, ALT, ALP, Glucose, and Triglycerides have increased in more polluted stations (P≤0.05). In sheer contrast, total protein and Albumin have decreased as pollution grows (P≥0.05). According to this study, environmental water pollution of the fish has a large impact on the concentration of measured blood parameters, whereas the influence of seasonal changes on most of them is low.

Histopathological studies reflect the overall health of a community in an ecosystem and can be used as a biomarker of pollutants, distinguishing the presence and amount of the pollutant within the organism as well as assessing the risks the organism is facing. These studies can also provide a range for the pollutant concentration to indicate healthy and polluted environments. In order to assess the defects brought by industrial pollutants the histopathological defects of Methylmercury (MeHg) were studied. Methylmercury, is the organic derivative of mercury, possessing more dangerous and harmful effects than mercury. Methylmerucry is highly hydrophobic and due to its lipophilicity, it penetrates through the blood brain barrier and targets the brain more than the other tissues. Therefore the effect of MeHg on Epinephelus coioides brain in the laboratory and in Zangi Creek were studied. Fish were adapted to the tanks and exposed to 10, 20, 40 and 80 mu g L-1 of methylmercury chloride in the Fisheries Center of Zangi Creek. The brains were collected on days 7, 14 and 30 of exposure and the depuration studies were performed for 7 and 14 days. The brains were dissected and sectioned for haemotoxylin and eosin staining and monitored under a microscope. The defects pertained hyperanemia and hemorrhage, karyolysis and necrosis, nuclear dust, endothelium hypertrophy, hydropic degeneration, vacuolation, cloudy swelling and edema. These defects were seen in different parts of the brain such as olfactory bulb, cereberum, optic lobe, cerebellum, diencephalon and medulla. The most defected part of the brain in response to MeHg seems to be the cerebellum. Depuration studies were performed for 7 and 14 days and mainly showed edema, cloudy swelling and hydropic degeneration in most parts (no rescue of phenotype seen). Fish were studied both in exposure to MeHg and preyed from field to compare the defects and assess the health and safety of the creek. The Histopathological Alteration Index (HAI) was assessed to show the amount of defects brought by the pollutant and revealed severe and irreversible defects in higher concentrations of exposure. Zangi Creek's HAI fell between the control group and the lowest MeHg concentration and is still considered as a safe site below the threat range.

Histomorphology of lymphatic structure associated in intestine in Persian sturgeon (Acipenser persicus) in warm and cold seasons

Background. Gut-associated lymphoid tissue (GALT), is a primary lymphoid tissue and a part of the mucosal lymphoid system. Depending on the location, it present as aggregations of lymphoid cells. There are several reports of structural differences in the lymphoid tissue attached to the gastrointestinal tract between different species of fish, as well as different areas of the gastrointestinal tract of a fish in the cold and warm seasons. Identifying and expressing these differences in terms of tissue structure, in addition to diagnosing aquatic diseases, is also of particular importance for vaccination and disease control. Material and methods. For this purpose, after collecting the desired samples routine histological procedure was performed and 4-6 mu m sections were obtained and were subsequently stained with hematoxylin-eosin, periodic acid-Schiff, and TUNEL immunohistochemical staining method. Results. The results showed that four main layers, i.e., tunica mucosa, tunica submucosa, tunica muscularis, and tunica serosa, were observed in the wall of the gut of Arabibarbus grypus (Heckel, 1843), as had been observed in other teleosts. GALT was seen in two different shapes in two areas. The former consisted of intra-epithelial scattered cells, which were arranged in the pillar structures and extended to the upper regions of the epithelium, but were more concentrated in the mid bases. The latter was found in lamina propria and submucosa regions. In the lamina propria, they had a strip-shaped arrangement and were placed in several rows below the base membrane, but in the submucosa, they were scattered and less densely packed. Micrometric results showed that not only the distribution of the lymphocytic cells in the intestine of both male and female specimens varied in different areas but also in some areas, the difference was statistically significant in both cold and warm seasons (P < 0.05). TUNEL immunohistochemical staining revealed that the number of apoptotic cells in both sexes was more in the anterior part of the intestinal bulb and in the posterior part of the proper intestine in the warm season compared to the cold season. Conclusion. Based on a recent study on gut-associated lymphoid tissue in A. grypus in two warm and cold seasons revealed that mucosal immunity is more active in the cold season than in the warm season.

Non-native ascidians are becoming a global problem and several species have recently been used as models for studying invasion success in the marine realm. Despite a limited dispersal due to their short-lived larvae, they are often found in coastal habitats as a result of human activities. As one of the warmest waterways in the world characterized by heavy marine traffic, the Persian Gulf is particularly prone to invasive ascidians. This study is the first to have documented the occurrence of the colonial ascidian Didemnum psammatodes in natural and man-made substrates in intertidal zones at 15 study sites in Qeshm and Hengam Islands in the Eastern Persian Gulf. High densities of D. psammatodes were observed at several study sites located far from major ports, but close to human residences, which may be explained by the prevalence of hard-surface man-made substrates.

Sea snakes are the largest group of marine reptiles, but their role in the food chain in their habitats remains unknown. Histological studies of the oral cavity in sea snakes are essential to interpret food habits and to identify the structure of poison glands. The Present research is designed to study the Histology of the oral cavity in sea snake Hydrophis cyanocinctus. For this purpose, 6 individuals of sea snakes were collected from Minab, Hormozgan. Then the sections were taken from the Palate and floor of the mouth. Sections were stained by H&E and PAS, and observed with a light microscope. The results showed that the epithelium was keratinized, stratified squamous, and specialized. The lamina propria contained lymphoid tissue. In the submucosa, the nucleated RBC, Heterophil cells, and connective tissue cells were observed. The glandular tissue was serosal and the mucosal gland and the muscle layer were observed skeletal. Mucosal glands and some parts of epithelium were PAS-Positive. The results of this study showed that in spite of many similarities between the histological structures of H. cyanocinctus and other snakes and reptiles, some significant structural differences exist in which can be defined as a specific model for sea snakes.

Study of blood biochemistry provides low cost tools to assess the health condition in live reptiles. Even it is useful to identify the changes of visceral organ function prior to the sign of the clinical abnormality. This research has investigated natural values of some most important blood biochemical parameters of sea snake H. cyanocinctus in Minab city of the Oman sea. For this purpose blood was collected from 10 adult male and female snakes from ventral tail vein in winter. Then samples were taken to the central laboratory of Minab in standard conditions. Parameters including sodium, potassium, chloride, calcium, magnesium, glucose, albumin, urea, total protein and creatinine measured after separation of serum and obtained results were compared with male and female snakes by t-test. Comparative studies of male and female samples showed significant statistical differences of some parameters including calcium, glucose and albumin. In comparison the values of this parameters in females was more than males. But, in other parameters no significant differences was detected. Also magnesium was the lowest amount and was seen in females while sodium was the highest amount and was seen in males. Results obtained in these species have differences and similarities to the other species that have been examined in the present study.

The aim of the current study was to investigate the histological and histochemical characteristics of large and small intestines of sea snake, Hydrophis cyanocinctus. Six adult sea snakes were collected from Minab beaches, located near the sea of Oman, in November, euthanized with chloroform, dissected and alimentary canal removed, tissues preparaed for sectioning and staining with Hematoxylin and Eosin (H&E) and Periodic Acid Schiff's (PAS) methods, and observed with a light microscope equipped with a dinolite lens. Histological evaluation showed that the walls of each organ was formed of mucosa, submucosa, muscularis and serosa. The wall of the small intestine has numerous circular folds with zigzag patterns. Epithelium of small intestine is composed of simple long columnar and goblet PAS positive cells. The epithelial layer of large intestine was formed of long simple columnar cells with acidophilic cytoplasm. Also, PAS positive goblet cells were found scattered in epithelial tissue. In histometry, the epithelial length and width in primary of small intestine was larger than other parts. Goblet cells with 15.36 ± 1.12 were more frequent in the large intestine. Thickness of both internal and external muscular layers were the most at the end of small intestine (p ≤ 0.05).