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In vitro studies on steroid metabolism by gonadal tissues from ambisexual teleosts. II. Conversion of [14C]androstenedione by the heterologous gonadal tissues of the protandric sea bream Pagellus acarne (Risso).

The heterologous gonadal tissues of the protandric sea bream Pagellus acarne were incubated with [14C]androstenedione in vitro. The tissues were taken from two males, an inverting specimen, and a female in early April. Although the testicular tissue regresses in the inverting fish the rate of 11 beta-hydroxylation in the male part of the gonad is at least as high as in the homologous portion of the "pure" male. No difference was found in the enzymatic pattern between the ovarian part of the inverting animal and that of the female. There is, however, a striking distinction in the metabolic activities of the pooled ovarian parts from two males and the homologous tissues from the inverting and female animals. They concern mainly the activities of 11 beta-hydroxylase and 17 beta-HSD. Moreover, ring A-reduction and the ratio of 5 alpha/5 beta-reduced metabolites differ considerably from the corresponding gonadal tissues taken from the inverting and the female specimen. The possible physiological meaning of these findings remains to be elucidated.

Animals

The sea bream liver contains receptors for growth hormone and prolactin.

Different tissues of the black sea bream Mylio macrocephalus including the liver, gills, intestine, muscle, gonad, swim bladder, spleen, heart and kidney were examined for the presence of prolactin and growth hormone receptors. Membranes were prepared from the tissues and 125I-labeled ovine prolactin and bovine growth hormone were used as ligands. It was found that the liver contained the highest level of specific 125I-labeled ovine prolactin and bovine growth hormone binding, suggesting the existence of hepatic prolactin and growth hormone receptors. The protein nature of the hepatic growth hormone receptor was revealed by the reduction of specific 125I-labeled growth hormone binding after treatment of hepatic membranes with trypsin and chymotrypsin.

Animals

Immunocytochemistry of somatotrophs, gonadotrophs, prolactin and adrenocorticotropin cells in larval sea bream (Sparus auratus) pituitaries.

The chronological appearance of endocrine cells in the pituitary of sea-bream (Sparus auratus) larvae was studied using antisera against salmon prolactin, trout growth hormone, salmon gonadotropin and N-terminal human adrenocorticotropin. The larval pituitary (1-12 days after hatching) was oval in shape and was composed of a dense mass of cells with few neurohypophysial fibres. By 60 days after hatching it began to resemble the adult and was divisible into a distinct rostral pars distalis containing prolactin and adrenocorticotropin cells; a proximal pars distalis containing somatotrophs and gonadotrophs and a pars intermedia. Cells immunoreactive with antisera against growth hormone were observed immediately after hatching (2 days post-fertilization). Weakly staining prolactin cells were observed 2 days later in the region corresponding to the rostral pars distalis. Cells immunoreactive with antigonadotropin and anti-adrenocorticotropin sera were observed in the pituitary 6 and 8 days after hatching, respectively. All the cell-types studied were immunoreactive from the time they were first identified until the final samples 90 days after hatching.

Adrenocorticotropic Hormone

[Histogenesis of Sea Bream (Pagrus major) enameloid].

The enameloid matrix consists of a collagenous matrix, and non collagenous proteins. Mature enameloid is highly mineralised similarly to mammalian enamel a large amount of the protein being removed. This is in contrast with bone, cementum, and dentin, where a large amount of collagen remains in the completed tissue. From the results of a biochemical study it has been suggested that the decrease of a major part of both the collagenous protein in developing enameloid is brought about by proteolytic enzymes (Kawasaki et al. 1987). However, histological and histochemical observations were not made at that time. In this study fourty-five live specimens of Sea Bream (Pagrus major) were used for histological and histochemical observations. Four undemineralised serial cryostat sections were obtained from each tooth garm and the developing enameloid matrix was observed ultrastructurally. The results of this study, show that the proteolytic enzyme activity which could not be detected in the enameloid formative stage, but was demonstrable after mineralisation had spread across the thickness of the matrix. Further more, the stage at which the proteolytic enzyme could be obtained was related to the stage of ALPase activity found in the dental epithelial cells.

Animals

Developmental expression of the growth hormone gene in the gilthead sea bream Sparus aurata.

Expression of growth hormone (GH) gene during early stages of larval development of the teleost Sparus aurata was determined by Northern blot analysis. Poly(A+) RNA was prepared from a pool of larvae collected on different days after hatching. When hybridized to Sparus aurata GH cDNA, GH specific mRNA was first seen on day 6 post-hatching. In contrast, the levels of beta-actin mRNA, which was used to normalize for RNA amounts, were already high on the day of hatching. Our results suggest that expression of the GH gene is very low immediately after hatching, and increases dramatically within 6 days.

Animals

Morphology and ultrastructure of Cryptobia eilatica n. sp. (Bodonidae: Kinetoplastida), an ectoparasite from the gills of marine fish.

A marine kinetoplastid flagellate, Cryptobia eilatica n. sp., is described from the gills of cultured gilt-head sea bream Sparus aurata L. and wild black-spot sea bream Diplodus noct (Valenciennes) in the Red Sea. The trophozoite is elongated and lacks a contractile vacuole and undulating membrane. The body averages 13.5 x 4.1 microns, anterior flagellum 9.7 microns and free portion of recurrent flagellum 15.2 microns. The ultrastructural features of the species exhibit great similarity to various previously studied Cryptobiids. Cryptobia eilatica trophozoites feed on bacteria, show a preference for the branchial interlamellar crypts, and attach to the host epithelium by means of the recurrent flagellum. Neither penetration into the epithelial cells, nor any direct damage to host tissue was observed. Cryptobia eliatica inhabits a purely marine habitat, but its trophozoite tolerates salinities as low as 10 ppt.

Animals

Relationship between essential fatty acid requirements of aquatic animals and the capacity for bioconversion of linolenic acid to highly unsaturated fatty acids.

1. [1-14C]linolenic acid was injected into the rainbow trout, Salmo gairdnerii, ayu, Plecoglossus altivelis, eel, Anguilla japonica, red sea bream, Chrysophrys major, rockfish, Sebastiscus marmoratus, globefish, Fugu rubripes rubripes and prawn, Penaeus japonicus (molting stage D"1-D2), and the bioconversion of linolenic acid (18:3 omega 3) to highly unsaturated fatty acids such as eicosapentaenoic (20:5 omega 3) and docosahexaenoic (22:6 omega 3) acids was investigated. 2. Linolenic acid was converted to 20:5 omega 3 and 22:6 omega 3 intensively in the rainbow trout, moderately in the ayu, eel and prawn, but slightly in the red sea bream, rockfish and globefish. 3. These results were discussed in relation to the essential fatty acid requirements of the aquatic animals.

Animals

Enzymatic properties of fish muscle aldolase.

1. Aldolases were isolated from the ordinary muscle of red sea bream Pagrus major, Pacific mackerel Scomber japonicus, and carp Cyprinus carpio by ammonium sulfate fractionation, followed by ion-exchange chromatography on DEAE-cellulose and CM-Sepharose CL-6B columns, and examined for enzymatic properties. 2. The aldolases showed the highest activity in a pH range from 6.8-7.8 Km values for fructose-1,6-bisphosphate ranged from 0.025-0.10 mM. 3. Irrespective of fish species, aldolase activity was inhibited by ATP, ADP, and AMP. ATP showed the strongest inhibition and was competitive with fructose-1,6-bisphosphate. 4. The aldolases did not require divalent metal ions for activation and were completely inhibited at 0.1 mM Cu2+. 5. Thermal inactivation of the enzymes was of the first-order reaction. Red sea bream, Pacific mackerel and carp enzymes lost the activity by 50% when incubated at 50 degrees C for 8, 14 and 23 min, respectively.

Adenine Nucleotides

Enzymatic properties of glyceraldehyde-3-phosphate dehydrogenase from fish muscle.

1. Glyceraldehyde-3-phosphate dehydrogenase was isolated from the ordinary muscle of red sea bream Pagrus major, Pacific mackerel Scomber japonicus and carp Cyprinus carpio by ammonium sulfate fractionation, followed by DEAE-Sepharose CL-6B and DEAE-cellulose column chromatography and Sephadex G-150 gel filtration, and examined for enzymatic properties. 2. Their optimum pH values in the backward reaction ranged from 7.8 to 8.2, and Km values from 1.56 to 1.90 mM. 3. Irrespective of the species of fish, the enzymatic activity was non-competitively inhibited by inorganic phosphate in the backward reaction. Divalent metal ions were not necessary to activate these glyceraldehyde-3-phosphate dehydrogenases. In the presence of 1 mM Zn(2+), these enzymes showed relative activities of 42-64% the activities measured in the absence of those ions. 5. Thermal stability of carp enzyme was higher than those of red sea bream and Pacific mackerel; the enzyme activity of the latter two species was almost lost on incubation at 45 degrees C for 10-20 min, whereas carp enzyme retained half the activity even when incubated at 60 degrees C for 30 min.

Animals

Histochemistry of glycoconjugates in the gallbladder epithelium of ten animal species.

A battery of seven lectins and several conventional mucin histochemical techniques were used to identify the epithelial mucins of the gallbladder of ten species: man, rabbit (Oryctolagus cuniculus, mammalia), hamster (Mesocricetus auratus, mammalia), chicken (Gallus gallus, bird), sparrow (Passer domesticus, bird), moorish gecko (Tarentola mauritanica, reptilia), ladder snake (Elaphe scalaris, reptilia), lake frog (Rana perezi, amphibia), natterjack toad (Bufo calamita, amphibia) and gilthead sea bream (Sparus auratus, fish). Glycogen was found in the epithelial lining of the reptilian and amphibian gallbladders. Sulphate and carboxyl groups were frequently found in the same species, except in the ladder snake and natterjack toad gallbladders where only sulphate groups were identified. Sialic acid residues were detected in man, rabbit, bird, T. mauritanica, R. perezi and fish gallbladders. ConA binding pattern was similar in the ten species studied. In the human gallbladder only PNA failed to label the luminal surface, while the glands were only unreactive to DBA. The human gallbladder showed a large variety of saccharides. The present results suggest that no relation exists between the composition of the gallbladder mucins and the situation of the species in the phylogenetic scale.

Animals

An immunocytochemical and ultrastructural study of the endocrine pancreas of Sparus auratus L. (Teleostei).

The pancreatic endocrine cells of Sparus auratus (gilthead sea bream) are concentrated in two or three principal islets, or Brockmann bodies, and numerous smaller islets embedded in the exocrine tissue. Insulin-, glucagon-, somatostatin-, and pancreatic polypeptide (PP)-immunoreactive cells were identified in all pancreatic islets of S. auratus using an indirect immunocytochemical (PAP) method. Insulin-immunoreactive cells were found in the central region of the islets. Glucagon-immunoreactive cells could be seen at the periphery of the islets and isolated in the exocrine tissue surrounding the large principal islet. Somatostatin-immunoreactive cells were distributed throughout the islets. PP-immunoreactive cells were clustered, in a limited shallow section, being found in no other part of the large principal islet whereas, in the smaller islets, these cells were more numerous and found in the whole peripheral area. Four cell types were identified in the pancreatic islets of S. auratus by electron microscopy. A,B,D and PP cells were characterized by the shape, size, and electron density of their respective secretory granules.

Animals