Endocrinology of the head-kidney tissues in teleost fish

This is a study of the structure and functions of the endocrine tissues in the head-kidney of the teleost fish, the homologous tissues to the mammalian adrenal cortex (=adrenocortical tissue) and adrenal medulla (=chromaffin tissue). The study is divided into three main sections: 1.The first section comprises a study of the general morphology, at the anatomical and histological level, of the different types of head-kidney which occur in teleost fish. The range of types is illustrated by studies on twenty-four species, some of which have been previously investigated, and including in particular sixteen marine species from the Red Sea coast of Saudi Arabia collected by the author. 2. The second section of this thesis comprises a detailed study of the morphology of the head-kidney of one particular species, Phoxinus phoxinus (Linnaeus), and a two year study of seasonal variations in the activity of its adrenocortical and chromaffin tissue. Samples of fish were collected from a population in the Walton Reservoir, Scotland, at monthly intervals. The activity of the adrenocortical tissue was assessed by measuring nuclear diameter of the adrenocortical cells, a criterion already widely used for this purpose. The activity of the chromaffin cells was similarly assessed, though the methodology is less well established in this case. The effects were compared of electro-fishing followed by anaesthesis and immersion in Bouin's fixative while still under electronarcosis. Both proved to be relatively stress-free methods. 3. The third section of this thesis comprises a study of the fine structure of the endocrine tissues of the head-kidney of Phoxinus phoxinus and Salmo qairdnerii. Electron micrographs were prepared using fish caught under stress-free conditions in the Walton Reservoir, and from aquarium-maintained fish. The adrenocortical cells in both species are characterised by having a great many conspicuous mitochondria with tubule-vesicular internal structure. The nucleus is circular in section, and centrally situated in the cell. There is an extensive smooth endoplasmic reticulum and numerous ribosomes, Microvilli occur on cell surfaces in contact with veins. There is a wide range in the structure of the adrenocortical cells of individual fish; mitochondria range from small, elongated structure, with dark matrix to large, circular structures in which the internal structures eventually breaks down. The cytoplasm as a whole tends to be pale in cells with small dense mitochondria, and dense in cells with large, paler mitochondria. Pale highly vacuolated cytoplasm is associated with cells in which the mitochondria are breaking down; the vacuoles are probably associated with cells in which the mitochondria are breaking down; the vacuoles are probably associated with the degenerating mitochondria, In Phoxinus maintained in aquaria for twenty-four hours before killing, the proportion of adrenocortical cells with small mitochondria with dark matrices, -. as compared to fish caught by stress-free methods and fixed immediately. In Salmo which had been maintained in aquaria for longer periods, the proportion oft- cells showing mitochondrial degeneration and cytoplasmic vacuolation is higher. It is concluded that small, dark matrix mitochondria are typical of early stages of adrenal activity; dense cytoplasm and an increased number of large, circular mitochondria are typical of maximum activity; and mitochondrial degeneration and vacuolation of the cytoplasm is typical of exhaustion. Chromaffin cells, not hitherto described in teleost fish, are of the type found in other vertebrates, with many chromaffin vesicles containing varying amounts of granular inclusion. Synaptic contacts occur commonly, apparently all of cholinergic type. In Salmo the chromaffin and adrenocortical cells lie separately, but in Phoxinus the adrenocortical cells form a sheath round the posterior cardinal veins and their main tributaries, and the chromaffin cells lie beyond them, against the haemopoietic tissue. These chromaffin cells communicate with the vein by elongated projections running amongst the adrenocortical cells

Toxico-histological Effects of Sublethal Concentrations of Lead Nitrate on the Gills of the African Catfish, Clarias gariepinus

170-175This study aimed to investigate the effects of subleathal lead doses on the histological architecture of gills in the freshwater African catfish, Clarias gariepinus. Results revealed three stages of changes after exposure to three doses of lead nitrate. The changes were mild in fish exposed to 16.12 mg/L of Pb (NO3)2 (stage I 20% of LC50) and severe in case of 40% of LC50 (stage II, 32.24 mg/L) and 60% of LC50 (stage III 48.37% mg/L) in comparison to control. The histological examination revealed normal architecture of gills in control fish. Normal gills were characterized with primary gill lamellae with a central hyaline cartilage. However, three-stage changes were observed after exposure to the three doses of lead nitrate. In stage I, a cartilaginous matrix appeared along with loosening of the epithelial lining of the cartilaginous core and abundant vascular spaces were observed on the secondary gill lamellae. An extra cartilaginous matrix, loosening of the epithelial lining of the cartilaginous core, de-shaped gill lamellae, and degeneration of the secondary gill lamellae were noted in stage II. Lesions in the gill pattern in stage III were represented by shortening of the tips of secondary gill lamellae, damaged gill lamellae, a cartilaginous matrix, and hyperplasia. This indicated that lead exposure resulted in severe histopathological changes in the gills in a dose-dependent manner

Lead Nitrate Induced Histopathological Alterations in the Liver and Intestine of African Catfish Clarias gariepinus Exposed to Sublethal Concentrations

552-557Studies were carried out on the liver and intestine tissue of Clarias gariepinus after exposure to sublethal concentrations of LC50 lead nitrate for 20 days. Fish were distributed into four groups, control (0 mg/L, LC50 of Pb(NO3)2) and three groups exposed to 20, 40 and 60% of the LC50 of Pb(NO3)2 (16.12, 32.24 and 48.37 mg/L respectively). Section of hepatic and intestine tissues showed the normal structure for control group. However, treated hepatic tissues of fish exhibited altered its characteristic architecture, with remarkably high vacuolation in hepatocytes and hepatoctolysis. Also, central vein was dilated and increased hemorrhage in the sections of almost samples from treated fish. Increased number of fibroblasts and Kuppffer cells were observed in the examined sections from treated fish when compared to the control. Therefore, fish treated with 60% LD50 of Pb(NO3)2 observed the proliferation of fibrous in connective tissue particularly near sinusoids and substituting liver parenchyma. Therefore, intestinal sections from the different treated fish groups revealed an evident harmful to intestinal tissue, especially in enterocytes and structures of villi. Also, disturbed longitudinal and circular muscularis were observed, to abnormally dilated, lamina propria, was infiltrated with a huge numbers of inflammatory leukocytes. Mucous secreting goblet cells proliferated and multiplied in all exposed fish

Toxico-histological Effects of Sublethal Concentrations of Lead Nitrate on the Gills of the African Catfish, Clarias gariepinus

This study aimed to investigate the effects of subleathal lead doses on the histological architecture of gills in the freshwater African catfish, Clarias gariepinus. Results revealed three stages of changes after exposure to three doses of lead nitrate. The changes were mild in fish exposed to 16.12 mg/L of Pb (NO3)2 (stage I 20% of LC50) and severe in case of 40% of LC50 (stage II, 32.24 mg/L) and 60% of LC50 (stage III 48.37% mg/L) in comparison to control. The histological examination revealed normal architecture of gills in control fish. Normal gills were characterized with primary gill lamellae with a central hyaline cartilage. However, three-stage changes were observed after exposure to the three doses of lead nitrate. In stage I, a cartilaginous matrix appeared along with loosening of the epithelial lining of the cartilaginous core and abundant vascular spaces were observed on the secondary gill lamellae. An extra cartilaginous matrix, loosening of the epithelial lining of the cartilaginous core, de-shaped gill lamellae, and degeneration of the secondary gill lamellae were noted in stage II. Lesions in the gill pattern in stage III were represented by shortening of the tips of secondary gill lamellae, damaged gill lamellae, a cartilaginous matrix, and hyperplasia. This indicated that lead exposure resulted in severe histopathological changes in the gills in a dose-dependent manner

Effects of Sub-lethal Lead Nitrate and Copper Sulfate Concentrations on Hematological Parameters During Long-term Exposure in Nile tilapia (Oreochromis niloticus)

437-441Nile tilapia (Oreochromis niloticus) weighing 51.66 ± 2.42 g were exposed to 0%, 20%, 40%, and 60% of LC50 to either lead nitrate (Pb(NO3)2) or copper sulfate (CuSO4) for 30 days. The Pb(NO3)2 and CuSO4 concentrations employed in the treatments of this study were 8.8, 17.6, and 26.4 mg/L and 2.57, 5.14, and 7.71 mg/l, respectively, and multiple hematological variables were evaluated. The red blood cell (RBC) count for the control group was 2.41 ± 0.13 while those of the treatment groups exposed to 8.8, 17.6, and 26.4 mg/L of Pb(NO3)2 were 2.21 ± 0.10, 1.94 ± 0.16, and 1.36 ± 0.10 × 106/µl, respectively, at the end of the study. Similarly, the hemoglobin (Hb), hematocrit (Hct), mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC), and platelet (PLT( levels significantly decreased as the Pb(NO3)2 concentration increased (p 4, showed decrease in the levels of RBC, Hb, Hct, WBC, and PLT when the concentration of CuSO4 increased, while the MCHC, MCH, and MCV levels significantly increased

Effect of feeding different carbohydrate to lipid ratios on the growth performance and body composition of nile tilapia (oreochromis niloticus) fingerlings1^1

In this study, we evaluated the growth performance and body composition of Nile tilapia (Oreochromis niloticus) fed five isonitrogenous and isoenergetic diets (A, B, C, D and E) containing varying levels of carbohydrates (18.27-40.37% ) and lipids (8.14-19.53% ) with carbohydrate-to-lipid (CHO/LIP) ratios ranging from 4.95 to 0.94. Significant ($P < 0.05$) differences were observed in the body weight gain, condition factor, specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), net protein retention (NPR) and apparent net energy retention (ANER) values of fish fed diets with different CHO/LIP ratios. The A, B and C diets with CHO/LIP ratios ranging from 4.95 to 2.06 did not result in any difference ($P > 0.05$) in fish performance. Decreasing the CHO/LIP ratio to 1.38 (diet D) significantly ($P < 0.05$) reduced growth rate and feed efficiency. A further decrease in the CHO/LIP ratio to 0.94 (diet E), however, did not affect ($P > 0.05$) these values any more. The hepatosomatic index (HSI) increased with a decrease in the CHO/LIP ratio and was the highest (1.81) with a CHO/LIP ratio of 0.94 and lowest (1.33) with a CHO/LIP ratio of 4.95. No significant ($P > 0.05$) differences were observed in the HSI values between the fish fed diets B, C and D with CHO/LIP ratios ranging from 3.33 to 1.38. The body compositions of the fish were significantly affected ($P < 0.05$) by different CHO/LIP ratios in the diets. Body moisture and crude protein contents decreased whereas fat and ash contents increased with decreasing CHO/LIP ratios. The CHO/LIP ratio in the diets did not, however, affect ($P > 0.05$) the gross energy content of the fish. The results of the present study indicate that the optimal dietary CHO/LIP ratio for a maximum growth performance of Oreochromis niloticus ranges between 2.06 and 4.95.Effets de divers régimes alimentaires à base de glucides et de lipides sur la croissance et la composition corporelle du Tilapia (Oreochromis niloticus) fingerling. Cette étude avait pour but d'évaluer les performances de croissance et la composition corporelle du Tilapia (Oreochromis niloticus) alimenté avec différents régimes isoazotés et isoénergétiques (A, B, C, D, et E) contenant 18,27 à 40,37 % de glucides (CHO) et 8,14 à 19,53 % de lipides (LIP), dans des proportions CHO/LIP variant de 4,95 à 0,94. Des différences significatives ($P < 0,05$) ont été observées sur les valeurs de gain de poids corporel, de coefficient de condition (k), de taux de croissance spécifique (SGR), d'indice de consommation (FCR), de coefficient d'efficacité protéique (PER), de rétention protéique nette (NPR) et de rétention en énergie nette apparente (ANER). Les performances de croissance n'ont pas été significativement différentes ($P > 0,05$) entre les régimes A, B et C (rapport CHO/LIP variant de 4,95 à 2,06). En revanche, la diminution du rapport CHO/LIP à 1,38 (régime D) a diminué le taux de croissance et l'efficacité alimentaire ; une diminution plus importante jusqu'à 0,94 (régime E) n'a pas eu d'effet plus notable ($P > 0,05$). L'indice hépatosomatique (HSI) a augmenté avec la décroissance du rapport CHO/LIP et a atteint un maximum (1,81) avec une valeur de CHO/LIP égale à 0,94 et un minimum (1,33) avec une valeur de 4,95. Aucune différence significative ($P > 0,05$) n'a été observée entre les régimes B, C et D (CHO/LIP variant de 3,33 à 1,38) pour les valeurs de HSI. Les teneurs corporelles en eau et en protéines ont été diminuées alors que celles en gras et en cendres ont augmenté avec la diminution du rapport CHO/LIP ($P < 0,05$). En revanche, la teneur en énergie brute n'a pas été affectée ($P > 0,05$). Les résultats de l'étude montrent que le rapport CHO/LIP optimal pour une croissance maximale du tilapia (Oreochromis niloticus) se situe entre 2,06 et 4,95

Effect of feeding different carbohydrate to lipid ratios on the growth performance and body composition of nile tilapia (oreochromis niloticus) fingerlings1^1

In this study, we evaluated the growth performance and body composition of Nile tilapia (Oreochromis niloticus) fed five isonitrogenous and isoenergetic diets (A, B, C, D and E) containing varying levels of carbohydrates (18.27-40.37% ) and lipids (8.14-19.53% ) with carbohydrate-to-lipid (CHO/LIP) ratios ranging from 4.95 to 0.94. Significant ($P < 0.05$) differences were observed in the body weight gain, condition factor, specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), net protein retention (NPR) and apparent net energy retention (ANER) values of fish fed diets with different CHO/LIP ratios. The A, B and C diets with CHO/LIP ratios ranging from 4.95 to 2.06 did not result in any difference ($P > 0.05$) in fish performance. Decreasing the CHO/LIP ratio to 1.38 (diet D) significantly ($P < 0.05$) reduced growth rate and feed efficiency. A further decrease in the CHO/LIP ratio to 0.94 (diet E), however, did not affect ($P > 0.05$) these values any more. The hepatosomatic index (HSI) increased with a decrease in the CHO/LIP ratio and was the highest (1.81) with a CHO/LIP ratio of 0.94 and lowest (1.33) with a CHO/LIP ratio of 4.95. No significant ($P > 0.05$) differences were observed in the HSI values between the fish fed diets B, C and D with CHO/LIP ratios ranging from 3.33 to 1.38. The body compositions of the fish were significantly affected ($P < 0.05$) by different CHO/LIP ratios in the diets. Body moisture and crude protein contents decreased whereas fat and ash contents increased with decreasing CHO/LIP ratios. The CHO/LIP ratio in the diets did not, however, affect ($P > 0.05$) the gross energy content of the fish. The results of the present study indicate that the optimal dietary CHO/LIP ratio for a maximum growth performance of Oreochromis niloticus ranges between 2.06 and 4.95.Effets de divers régimes alimentaires à base de glucides et de lipides sur la croissance et la composition corporelle du Tilapia (Oreochromis niloticus) fingerling. Cette étude avait pour but d'évaluer les performances de croissance et la composition corporelle du Tilapia (Oreochromis niloticus) alimenté avec différents régimes isoazotés et isoénergétiques (A, B, C, D, et E) contenant 18,27 à 40,37 % de glucides (CHO) et 8,14 à 19,53 % de lipides (LIP), dans des proportions CHO/LIP variant de 4,95 à 0,94. Des différences significatives ($P < 0,05$) ont été observées sur les valeurs de gain de poids corporel, de coefficient de condition (k), de taux de croissance spécifique (SGR), d'indice de consommation (FCR), de coefficient d'efficacité protéique (PER), de rétention protéique nette (NPR) et de rétention en énergie nette apparente (ANER). Les performances de croissance n'ont pas été significativement différentes ($P > 0,05$) entre les régimes A, B et C (rapport CHO/LIP variant de 4,95 à 2,06). En revanche, la diminution du rapport CHO/LIP à 1,38 (régime D) a diminué le taux de croissance et l'efficacité alimentaire ; une diminution plus importante jusqu'à 0,94 (régime E) n'a pas eu d'effet plus notable ($P > 0,05$). L'indice hépatosomatique (HSI) a augmenté avec la décroissance du rapport CHO/LIP et a atteint un maximum (1,81) avec une valeur de CHO/LIP égale à 0,94 et un minimum (1,33) avec une valeur de 4,95. Aucune différence significative ($P > 0,05$) n'a été observée entre les régimes B, C et D (CHO/LIP variant de 3,33 à 1,38) pour les valeurs de HSI. Les teneurs corporelles en eau et en protéines ont été diminuées alors que celles en gras et en cendres ont augmenté avec la diminution du rapport CHO/LIP ($P < 0,05$). En revanche, la teneur en énergie brute n'a pas été affectée ($P > 0,05$). Les résultats de l'étude montrent que le rapport CHO/LIP optimal pour une croissance maximale du tilapia (Oreochromis niloticus) se situe entre 2,06 et 4,95

Analysis of reproductive biology and spawning season of the pink ear emperor Lethrinus lentjan, from marine ecosystem

A total of 593 samples of Lethrinus lentjan (Lacepede, 1802) were collected from the Red Sea, Jeddah, Saudi Arabia, to study their productive biology and spawning season of the local population. Sampling was carried out on a monthly basis for a period of one year. The monthly sex ratios indicated that females were dominant throughout the study period, with an overall male:female sex ratio of 1:7.98, although males were larger than females. The highest monthly performance maturation index (PMI), as well as the male and female gonadosomatic index (GSI) and ovarian maturation rate (OMR) were observed in February and March. Histological examination of the gonads confirmed the process of sexual transformation in this fish species, wherein individuals mature first as female, and then change sex to male (protogynous hermaphroditism). Histological sections also showed that the sexual maturation of males of L. lenjtan comprised three main stages, while the sexual development of females could be classified into four main stages. Extended spawning in the form of batches released during different months throughout the year were recorded for this fish species, with the main spawning season in February and March, and an additional, shorter spawning season in September

Growth Performance and Body Composition of Nile Tilapia Oreochromis niloticus Fed Diets Containing Graded Levels of Seaweed Ulva lactuca

873-878Three experimental diets, including fish meal replaced with different ratios (20%, 40% and 60%) of Ulva lactuca and a seaweed-free control diet were used to evaluate the effect of dietary seaweed incorporation on the growth performance, feed utilization and body composition of the Nile tilapia, Oreochromis niloticus. The experiment lasted for 12 weeks and the results of the growth indicators; final weight (FW), weight gain (WG), percentage of weight gain (WG%), daily growth rate (DGR) and specific growth rate (SGR) indicated no significant differences (P>0.05) between the fish on the control diet (C) and those on a diet with 20% U. lactuca (U20), despite the fact that an outstanding performance of fish growth was accomplished on the control diet. Furthermore, no significant differences among C and U20 for the feed conversion ratio (FCR) and protein efficiency ratio (PER) whereas the feed utilization efficiency, FCR and PER decreased significantly when the proportion of U. lactuca meal was increased to 40% and 60% (U40 and U60). Carcass and muscle composition showed a similarity between the various groups. Moisture, protein and ash content showed an increase in line with the increase in U. lactuca meal in the diets, but the reverse was observed for the lipid level. The present study observed that U. lactuca meal attained considerable performance for feeding the Nile tilapia at dietary inclusion levels up to 20% without undesirable effects on growth performance and feed utilization efficiency