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El presente trabajo se enfoca al conocimiento del patrón reproductivo de la trucha arco-iris (Salmo gairdneri) de la piscifactoria el Zarco, México. Para obtener el articulo completo pueden contactar al Editor de la Revista Ecosistemas y Recursos Agropecuarios en el siguiente correo electrónico era@ujat.mx y se les enviará sin algún costo.

We studied the activities of digestive enzymes responsible for the digestion of food carbohydrate and protein components in plant-eating fish at various stages of larval development. The activities of all digestive enzymes tend to rise during larval development. Species specific features of the alimentary canal functioning have been described. [ABSTRACT FROM AUTHOR]

The D- and L-specific nicotine oxidases are flavoproteins involved in the oxidative degradation of nicotine by the Gram-positive soil bacterium Arthrobacter nicotinovorans. Their structural genes are located on a 160-kbp plasmid together with those of other nicotine-degrading enzymes. They are structurally unrelated at the DNA as well as at the protein level. Each of these oxidases possesses a high degree of substrate specificity; their catalytic stereoselectivity is absolute, although they are able to bind both enantiomeric substrates with a similar affinity. It appears that the existence of these enzymes is the result of convergent evolution. The amino acid sequence of 6-hydroxy- l-nicotine oxidase (EC 1.5.3.6) as derived from the respective structural gene shows considerable structural similarity with eukaryotic monoamine oxidases (EC 1.4.3.4) but not with monoamine oxidases from prokaryotic bacteria including those of the genus Arthrobacter. These similarities are not confined to the nucleotide-binding sites. A 100-amino acid stretch at the N-terminal regions of 6-hydroxy- l-nicotine oxidase and human monoamine oxidases A possess a 35% homology. Overall, 27.0, 26.9, and 25.8% of the amino acid positions of the monoamine oxidases of Aspergillus niger (N), humans (A), and rainbow trout (Salmo gairdneri) are identical to those of 6-hydroxy- l-nicotine oxidase (Smith–Waterman algorithm). In addition, the G+C content of the latter enzyme is in the range of that of eukaryotic monoamine oxidases and definitely lower than that of the A. nicotinovorans DNA and even that of the pAO1 DNA. The primary structure of 6-hydroxy- d-nicotine oxidase (EC 1.5.3.5) does not reveal its evolutionary history as easily. Significant similarities are found with a mitomycin radical oxidase from Streptomyces lavendulae (23.3%) and a ``hypothetical protein'' from Mycobacterium tuberculosis (26.0%). It is proposed that the plasmid-encoded gene of 6-hydroxy- l-nicotine oxidase evolved after horizontal transfer from an eukaryotic source. [ABSTRACT FROM AUTHOR]

The origin of arterio-venous anastomoses, connecting the efferent filament artery (EFA) with the central venous sinus (CVS) of gill filaments can be well discerned by scanning electron microscopy in the rainbow trout. Corresponding vessels between the afferent filament artery and the CVS could not be detected with the techniques applied. AVA-specific endothelial cells are characterized by their bulky shape and their microvillous surface. The general morphology of AVA's in Salmo gairdneri is very similar to that of AVA's in Tilapia mossambica (Vogel et al., 1974) but they are much longer in the trout. No filament whorls have been encountered in AVA endothelia of Salmo gairdneri. [ABSTRACT FROM AUTHOR]

About 1500 nerve cells were demonstrated in the pineal organ of the rainbow trout, Salmo gairdneri, by means of the acetylcholinesterase (AChE) reaction (Karnovsky and Roots, 1964). The diameter of these elements is 10-15 μm in the end vesicle of the pineal organ and only 5-8 μm in the pineal stalk. The number of the AChE-positive neurons per unit area increases from the pineal end vesicle to the pineal stalk; most of them belong to the pseudounipolar type. An intrapineal ganglion with large, multipolar neurons occupies a rostromedial position. These cells exhibit a strong AChE reaction and are surrounded by a dense network of fibers. Thin bundles of axons form fiber pathways in the lateral walls of the pineal end vesicle. These roots converge to the pineal tract that is located in the dorsal portion of the pineal stalk and runs toward the posterior commissure. Electron-microscopic studies of the pineal tract demonstrate 1700-2000 nerve fibers of two different structural types and calibers (1 and 2). At the level of the caudal end of the pineal stalk both types of nerve fibers are unmyelinated, whereas at the level of the subcommissural organ several of the Type-2 fibers are myelinated. In five rainbow trout the total fiber count of the pineal tract was correlated with the number of nerve cells present in the corresponding pineal organ. Some AChE-positive neurons accompany the pineal tract. In all rainbow trout examined the parapineal organ was located on the left side. AChE-positive nerve cells lie at the periphery of the parapineal organ. A well developed parapineal tract connects the parapineal organ with the left habenular ganglion. AChE-positive nerve cells are scattered around the parapineal organ and the parapineal tract. [ABSTRACT FROM AUTHOR]

Activity of trout pineal HIOMT was found to increase with increase in incubation temperature from 5 to 40 °C although the activation energy remained constant over this range. From examination of the effects of the products of HIOMT catalysis on the enzyme it was apparent that the catalytic mechanism was ordered Bi-Bi with S-adenosylmethionine as the obligatory first substrate. Trout HIOMT was found to methylate all the common pineal hydroxyindoles with hydroxytryptophol having the greatest affinity for the enzyme. The pH optimum for trout HIOMT was found to be about pH 9.0 although routine use of a pH of 7.9 is recommended to limit potentially deliterious effects caused by degradation of S-adenosylmethionine at elevated pHs. [ABSTRACT FROM AUTHOR]

In order to identify the cell-type responsible for the production of hypocalcin (the recently isolated hypocalcemic hormone of teleost fish), the corpuscles of Stannius (CS) of trout, flounder and goldfish, were immunocytochemically stained with antisera raised against trout hypocalcin. The secretory granules of the type-1 cells of the CS, considered to be the hypocalcin-producing cells, showed intense immunoreactivity in all species examined. However, in trout and flounder, the secretory granules produced by the type-2 cells, which have been suggested to represent a functionally different cell-type, also showed an intense immunoreactivity. In goldfish, no type-2 cells were observed. We tentatively conclude that type-1 and type-2 cells represent structurally different forms of the same functional cell-type. [ABSTRACT FROM AUTHOR]

Pancreatic islets of salmon contain at least two peptides of the glucagon family: 29-amino acid glucagon and 31-amino acid glucagon-like peptide (GLP). Both peptides were recently isolated from the pancreatic islets of coho salmon and sequenced (Plisetskaya et al. 1986). Antibodies generated against these two peptides and against human glucagon were used as immunocytochemical probes to investigate whether glucagon and GLP are processed in the same, or in different cell types in the pancreatic islets and the gut of salmon. Two salmonid species, rainbow trout and coho salmon, were studied. All islet A-cells in the two species were immunoreactive toward both anti-salmon (s)-glucagon and anti-s-GLP. Similar colocalization of glucagon and GLP immunoreactivities was found in open-type endocrine cells in mucosae of the small intestine (including the pyloric coecae) and the large intestine close to the vent of rainbow trout. None of the antibodies stained mucosal cells of the body of the stomach. These results suggest that in the pancreas and the gut of salmonid fish the same cells produce both glucagon and GLP. These peptides are most likely the products of a single gene coding for the preproglucagon sequence. [ABSTRACT FROM AUTHOR]

The angioarchitecture of the pineal organ of the rainbow trout ( Salmo gairdneri) was investigated by means of the corrosion-cast preparation method and scanning electron microscopy. Two main arteries (aa. epiphyseales) supply the pineal parenchyma. They emerge from the aa. cerebri anteriores and run in the fissure between the prosencephalon and the mesencephalon. After entering the pineal stalk, the aa. epiphyseales branch off into several arterioles, most of which extend to the pineal end-vesicle where they give rise to a lobular, bilaterally symmetric capillary network. Capillaries establishing the main portion of the pineal vessels appear widened in comparison to those supplying other portions of the brain and resemble capillaries in other endocrine organs. In Salmo gairdneri, no specialized system of portal vessels appears to exist between the pineal organ and other portions of the brain. [ABSTRACT FROM AUTHOR]

Rostral lobes of the pars distalis from rainbow trout, Salmo gairdneri, were incubated in vitro in a medium containing C-labelled lysine. The labelled proteins in these lobes and medium were separated by polyacrylamide gel electrophoresis, the prolactin eluted from the appropriate band, and injected into intact trout. Following the injections, various tissues were dissected out and observed autoradiographically. There was no binding of labelled prolactin to tissues of pituitary gland, thyroid, pyloric caecum, stomach, pancreas or muscle. There was, however, significant labelling in liver, intestine, kidney, bladder, skin and gill. The binding of labelled chum salmon prolactin to these latter tissues in vitro was significantly reduced when unlabelled hormone was also added. [ABSTRACT FROM AUTHOR]

The effect of angiotensin infusion on the glomerular ultrastructure of freshwater- and seawater-adapted rainbow trout, Salmo gairdneri, has been examined by scanning and transmission electron microscopy. Adaptation of trout to seawater resulted in epithelial podocyte flattening, primary process broadening and apparent loss of foot processes in almost all glomeruli, features which were uncommon in freshwater-adapted trout. Similar changes were induced by infusion of freshwater-adapted animals with angiotensin, suggesting that the renin-angiotensin system plays a role in the modification of glomerular epithelial ultrastructure. Adaptation of trout to seawater also reduced glomerular diameter, but infusion of freshwater-adapted animals with angiotensin did not mirror this effect. Infusion of angiotensin into seawater-adapted animals increased the overall thickness of glomerular basement membrane by increasing the lamina rara interna and lamina densa. This did not occur when freshwater-adapted fish were either infused with angiotensin or adapted to seawater. These findings suggest that other humoral systems are involved in the control of glomerular diameter and basement membrane thickness as part of an integrated response to increased environmental salinity. [ABSTRACT FROM AUTHOR]

An immunofluorescence technique using antibodies against the Fc and Fab fragments of human IgG (IgG) was used to study the absorption of proteins by the intestinal epithelial cells of rainbow trout after oral or anal administration. Cellular absorption of a high molecular weight protein, hepatitis-B surface antigen (HBsAg), was also studied by using two monoclonal antibodies, one specific for the conformation of the antigen (implying disulfide bridges), and the other that reacts with the constituent polypeptides. Both absorbed IgG and HBsAg were seen to be segregated in the apical vacuolar system, a characteristic feature of intestinal epithelial cells. The same antibodies were used with an everted sac technique in conjunction with immunofluorescence, to show the intravacuolar degradation of IgG and HBsAg following absorption. By using an antibody against cathepsin D, it was possible to demonstrate, by immunofluorescence, the localization of this enzyme in the same vacuolar system. After coupling the antibody to peroxidase or to the protein A/colloidalgold complex, the ultrastructural antigenic sites of cathepsin D could be seen to be localized in the interior of the vacuoles. The vacuolar localization of a cathepsin B activity was determined by incubating sections of intestinal mucosa, or isolated epithelial cells, with a specific synthetic substrate (Z-Ala-Arg-Arg-methoxynaphthylamide). The supranuclear hyaloplasmic vacuoles of intestinal epithelial cells may be considered to be phagolysosomes that assure the degradation of absorbed proteins. This function may be of fundamental importance in the nutritional processes of this species. [ABSTRACT FROM AUTHOR]

The structural modifications in the middle intestine of the trout, Salmo gairdneri, induced by transfer to seawater have been studied. During the first two days in seawater, significant distensions of the intercellular spaces are observed between the apical tight junctions and the basement membrane. These dilations are more frequent in the apical part of the intestinal folds. At the basal part of the cell, numerous lamellar processes open in the intercellular spaces. They are closely associated with elongated mitochondria, and are often mixed with small clear vesicles. After seven days in seawater, intercellular spaces are less expanded. Numerous mitochondria are observed in the apical part of the cell, and numerous myelinic bodies with dense granules lie near the nucleus. After one month in seawater, the epithelium resembles that of the freshwater controls; mitochondria are more numerous and other organelles are well developed. The most important modifications of the ultrastructure of the intestine mucosa occur during the first two days in seawater, in correlation with important physiological changes following the abrupt increase of environmental salinity. [ABSTRACT FROM AUTHOR]

Cyanoketone administered via the food (0.1, 0.2 and 2 mg/g) for 8 weeks from the first feeding (day 46 after fertilization) or via the aquarium water (3 and 30 mg/100 l) for 4 weeks from day 41 does not influence the activity of 3 β-hydroxysteroid dehydrogenase (3 β-HSD) in the interstitial cells of the gonads or interrenal cells of juvenile trout in vivo. However, the number of 3 β-HSD-positive interrenal cells was strongly increased by administration of the highest dose of cyanoketone via both routes. These high doses furthermore affect the sex ratio in favor of males. It is concluded that interrenal tissue is responsible for the masculinizing effect of cyanoketone via increased production of androgens and/or corticosteroids. Cyanoketone at concentrations of 0.01 to 100 μg/ml causes a dose-response inhibition of 3 β-HSD activity in the interrenal cells, when the substance is administered to an incubation medium for demonstration of this enzyme in tissue sections. The controversial in-vivo and in-vitro effects of cyanoketone on 3 β-HSD activity are discussed. [ABSTRACT FROM AUTHOR]

A process of elimination of the nucleus in oocytes of the rainbow trout displaying eight different stages is described. The phenomenon was observed only in stage III of sexual maturity. Initially, there is a slight shrinkage of the oocyte accompanied by the loss of yolk granules. This is followed by a cytoplasmatic protrusion into the ovarian lumen, which is covered by the follicular wall. Subsequently, the latter is ruptured and the nucleus migrates toward the opening. Finally, the nucleus leaves the follicle together with a portion of cytoplasm and then occasionally undergoes a breakdown into fragments in the ovarian lumen. The relevance of this mechanism in the process of preovulatory follicular atresia is discussed. [ABSTRACT FROM AUTHOR]

The central sinus, a prominent component of the nonrespiratory, ionoregulatory vasculature of the fish gill has been variously described as a simple sack-like structure in the eel A. anguilla and as an intricate series of parallel vessels in the catfish I. punctatus. To resolve whether these differences are interspecific or methodological, corrosion replicas of the central sinus in the rainbow trout ( Salmo gairdneri) were prepared at physiological and superphysiological perfusion pressures with a low-viscosity methyl methacrylate resin. At physiological perfusion pressure (30 mmHg, 4.0 kPa), the central sinus vasculature appears as a series of parallel vessels traversing the filament beneath, and in register with, the interlamellar filamental epithelium. At elevated perfusion pressure (55-65 mmHg, 7.3-8.7 kPa) the sinus becomes greatly distended and sack-like and the vessels appear to coalesce. These changes are most pronounced in the basal area of the filament and along the efferent filamental artery. The results show that the interpretation of the vascular organization of the central sinus is highly dependent on methodology. In addition, the sensitivity of the central sinus to changes in perfusion pressure suggests that the sinus plays a dynamic role in intrabranchial hemodynamics. [ABSTRACT FROM AUTHOR]

The most frequently occurring cell types in the pars distalis of the pituitary gland of the rainbow trout, (i) the lactotropic, (ii) the gonadotropic, and (iii) the somatotropic cells, were identified in cryosections. Their morphological characteristics were compared with those of Epon-embedded material. Cell location, cell form, position of the nucleus, arrangement of rough endoplasmic reticulum and sizes of secretory granules proved to be useful parameters for identification. The size distribution of secretory granules of corresponding cells in cryosections and Epon sections proved to be similar. Additionally, both the immunoferritin and the unlabeled antibody enzyme method were applied for the immunocytochemical labeling of gonadotropic hormone-producing cells in cryosections. Anti-salmon-GTH as well as anti-carp-GTH serum showed the presence of GTH in both the smaller and the larger granules of the classical GTH cells, but also produced a reaction in TSH cells. Labelling of TSH cells was absent when using anti- β-carp-GTH. Specificity of the reaction depended upon the degree of dilution of the anti-GTH serum. Results with dilutions of 1∶4,000 and 1∶8,000 in the unlabeled antibody enzyme method, and of 1∶8,000 up to 1∶32,000 in the immunoferritin technique were optimal. Acid phosphatase activity in the smaller granules was demonstrated by enzyme cytochemistry in Epon sections. The relationship of the presence of hormone in these granules is discussed. The high sensitivity of the immunocytochemical labeling procedure is discussed with respect to cryo-ultramicrotomy. [ABSTRACT FROM AUTHOR]

Gonadal sex differentiation in rainbow trout takes place between day (D) 45 and D 55 after fertilization. Until D 400 the male GSI is maintained at about 0.4‰, and that of the female at about 1‰. Treatment with N,N-dimethylformamide (DMF) influences the sex ratio and GSI, and is therefore unsuitable as a solvent for steroids to be added to the aquarium water for examination of their effects on gonadal sex differentiation. Triton X-100 has no such effect, and is used as the steroid solvent in the present experiments. Progesterone (300 μg/l) administered for 4 weeks from hatching, or from D 43, significantly affects the sex ratio in favour of females. Methyltestosterone given from hatching results in sterilization of the gonads, especially when the treatment is carried out for 8 weeks, or when a relatively high dose (300 μg/l) is used for 4 weeks. When given from D 43 methyl testosterone has a masculinizing effect. It is concluded that progesterone and androgen(s) are important in inducing the onset of ovarian and testis development, respectively. [ABSTRACT FROM AUTHOR]

In the maturation cycle of ovaries of cultured rainbow trout, three periods can be distinguished: (1) a period of ovulation and previtellogenesis (January-May), (2) a period of exogenous vitellogenesis (May-November/December), and (3) a period of maturation of oocytes (November/December-January). Enzyme cytochemical and electron microscopical data indicate that stroma cells (i.e., interstitial cells and special theca cells) and granulosa cells represent sources of steroids. Steroidogenesis in stroma cells is found throughout the annual cycle, reaching a peak activity in January and February. Weak steroidogenic activity is observed in the granulosa cells of exogenous vitellogenic follicles and young postovulatory follicles. Possible functions of steroids secreted by stroma cells and granulosa cells are discussed. [ABSTRACT FROM AUTHOR]

The pituitary gland is first evident in rainbow trout two weeks before hatching. Differentiation of prolactin and ACTH cells is not marked until 3-4 days after hatching when the follicular arrangement of the prolactin cells become apparent. There is no difference in the time of development of either prolactin or ACTH cells in larvae reared in different ambient salinities despite marked changes in tissue ion and water content. This suggests that prolactin and ACTH do not play the osmo- and iono-regulatory roles in larval rainbow trout that they are considered to play in adult salmonids. [ABSTRACT FROM AUTHOR]

In the maturation cycle of the testis of cultured rainbow trout, three periods can be distinguished: a period of spermatogonial proliferation (June-September), a period of maturation, spermiogenesis and spermiation (September-January), and a period of full spermiation (January-June). In the third period new primary spermatogonia are formed, and old sperm cells are resorbed. Sperm release occurs seldom, if ever in animals kept in captivity. The presence of 3β-HSD, 3α-HSD and G6PD activities, smooth endoplasmic reticulum and mitochondria with tubular cristae indicates steroidogenesis in Leydig cells. These parameters have been found during the annual cycle; the strongest steroidogenic activity is from January to June, when metabolic activities tend to shift to the pentose phosphate shunt. In June, most steroid synthesizing Leydig cells are abundant, at sites where seminiferous tubules contain primary and secondary spermatogonia. In November, a weak steroidogenic activity has also been demonstrated in Sertoli cells lining post-spermatogonial cysts. Other aggregations of steroid synthesizing cells are present outside the testis in the connective tissue surrounding the epithelium of vas deferens. The epithelium of the vas deferens shows positive reaction for 3α-HSD, G6PD, MD, LD and NADHD throughout the testicular cycle; 3α-HSD and G6PD activities are generally weak. Metabolic activity in this epithelium increases when sperm cells are stored in the lumen of the duct (November-June). Acid phosphatase in the epithelium of the vas deferens is more active during the period when sperm cells are resorbed. [ABSTRACT FROM AUTHOR]

The double antibody immunofluorescence technique was applied to serial coronal and sagittal sections of the brains of the trout, Salmo gairdneri, using an antibody against mammalian LH-RH. Immunoreactive material was found in small perikarya, situated at both sides of the ventriculus communis in the area dorsalis pars medialis of the telencephalon. The axons of these perikarya, also containing immunoreactive material, do not form a tract, but run diffusely in a caudo-ventral direction towards the pituitary stalk. The ending of these fibres has not yet been established. [ABSTRACT FROM AUTHOR]

The karyotypes of the rainbow trout ( Salmo gairdneri R.) and the brown trout ( Salmo trutta L.) were analyzed by means of silver staining and the chromomycin A/distamycin A/DAPI fluorescence banding technique. The nucleolus organizer regions (NORs) were localized at the secondary constrictions of chromosome no. 14 in S. gairdneri and of chromosome no. 10 in S. trutta. Additional silver positive dots were observed at or close to several centromeres in S. gairdneri. Brilliant chromomycin A (CMA) fluorescence heterochromatin blocks were localized on both sides of the nucleolar constrictions in S. gairdneri. A polymorphic CMA positive band was detected close to the NORs of S. trutta. No distamycin A/DAPI intense heterochromatin blocks were detected in the genomes of the two Salmo species investigated. [ABSTRACT FROM AUTHOR]

The central projections and terminations of the pineal nerve tract in rainbow trout, Salmo gairdneri, were studied using the cobalt chloride method developed for selectively staining nerve fibres by Pitman et al. (1972). A modification of the method is described for the first time making its use possible in the study of central pathways of the pineal nerve tract. The pineal tract consists of only pinealofugal fibers which project centrally over an extensive sensorimotor area in the brain. Along its course through the subcommissural-posterior commissure region it gives off several branches: The optic tectum and nucleus interpeduncularis are shown to be free of pineal terminals. Convincing evidence is presented showing total absence of pineal terminals in the subcommissural organ in trout. The possibility of direct innervation of the preoptic nucleus by pineal fibers is pointed out. The results are discussed in the light of existing evidence on pineal tract pathways in fishes as well as from an evolutionary viewpoint. The findings confirm some of the observations of other workers particularly those of Nils Holmgren (1917, 1918 a, b). It is proposed that the lack of success in fully describing the pineal tract pathways in fishes and the prevailing ambivalence are owing to methodological weaknesses and that the pattern of central projections described here for trout may prove to be generally true for other fishes as well. The advantages of cobalt chloride iontophoresis as a method for studying pineal innervation are pointed out. [ABSTRACT FROM AUTHOR]

During organ culture of the pituitary of Salmo gairdneri, the secretory granules of the ACTH cell migrate to the distal pole of the cell where they persist even over prolonged periods of culture. Electron microscope studies suggest that the granule contents are released from the cell and that the accumulated material is extracellular. Immunofluorescent studies demonstrate immunoreactive ACTH within the cell cytoplasm but none or little associated with the accumulated extracellular material. A dissociation between ACTH and the granule 'matrix' at about the time of granule release is proposed. [ABSTRACT FROM AUTHOR]