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PubMed2001

Comparative study of endocrine cells in the principal pancreatic islets of two teleosts, Silurus asotus (Siluridae) and Siniperca scherzeri (Centropomidae).

The regional distribution and relative frequency of some endocrine cells in the principal pancreatic islets of two teleosts, Silurus asotus Linne (Siluridae) and Siniperca scherzeri Steindachner (Centropomidae), which have similar feeding habits, were observed using specific antisera against insulin, glucagon, somatostatin and bovine pancreatic polypeptide (bovine PP) using the peroxidase antiperoxidase (PAP) method. Spherical to spindle shaped cells were demonstrated in the principal pancreatic islets in both species of teleost fishes. However, they were not detected in the exocrine portions nor the pancreatic ducts. Insulin-immunoreactive cells were located in the central regions of the principal pancreatic islets at high frequency in both species. Glucagonimmunoreactive cells were restricted to the peripheral regions of the principal pancreatic islets in both species. They formed a mantle zone in the peripheral regions of Silurus asotus with moderate frequency, and occupied a narrower mantle zone in Siniperca scherzeri with moderate frequency. In addition, glucagonimmunoreactive cell cores were also found in the peripheral zone of some principal pancreatic islets of Siniperca scherzeri. Somatostatin-immunoreactive cells were dispersed in the central zone of the principal pancreatic islets of Silurus asotus with moderate frequency, but were located in the peripheral regions with low frequency in Siniperca scherzeri. Bovine PPimmunoreactive cells were found in the peripheral region and the mantle zone of the principal pancreatic islets with low and rare frequency, respectively in both species. In conclusion, the regional distribution and relative frequency of endocrine cells in the principal pancreatic islets of Silurus asotus showed general patterns similar to those of other teleostean fishes. But, some speciesdependent distributional patterns and/or relative frequencies, particularly in glucagon-, somatostatin- and bovine PP-immunoreactive cells, were detected in the principal pancreatic islets of Siniperca scherzeri.

Animals↗
PubMed2004

[Structure and neurochemistry of the raphe nuclei in teleosts].

NO is an important modulator of the brain serotoninergic function as it is co-localized with 5-hydroxytryptamine in the neurons of raphe nuclei in the brain of all the higher vertebrates. In the brain of fishes this property of NO is poorly studied. The purpose of this work was to study the neuromorphological peculiarities and distribution of NO-ergic neurons in raphe nuclei of Teleost species--carps and perch-like fishes. Using standard neuromorphological methods and the histochemical reaction demonstrating NADPH-diaphorase activity, the comparative analysis of NO-ergic neurons was performed and their localization was studied in the raphe complex of five teleost species. Within the raphe complex in fishes two main nuclei--nucleus raphe superior and nucleus raphe inferior were demonstrated. NADPH-diaphorase activity was observed in practically all the neurons of raphe niclei in species examined. Some intergroup morpho-adaptational neurochemical differences were found in the of the ventro-medial reticular formation adjacent to the raphe complex.

Animals↗
PubMed2005

Morphological, histochemical and immunohistochemical study of the gill epithelium in the abyssal teleost fish Coelorhynchus coelorhynchus.

Histochemical and immunohistochemical study was carried out on nitrinergic innervation and neuroendocrine system in the gill epithelium of the abyssal fish Coelorhynchus coelorhynchus. The results showed that nNOS-positive nerve fibers, originating from the branchial arch were present in the subepithelial tissue of branchial primary filament. nNOS-positive neuroendocrine cells were also present in the primary filaments and secondary lamellae. Numerous mucous cells in the gill epithelium were AB/PAS-positive, while sialic acid was absent as confirmed by neuraminidase reaction and WGA lectin histochemistry. The mucus compounds in abyssal teleost fish are different from those found in pelagic species, being related to their living conditions. In abyssal species, greater numbers of chloride and neuroendocrine cells are involved in the movement of water and electrolytes. Neuroendocrine cells possess oxygen receptors which mediate the cardiovascular and ventilatory response to oxygen deficiency, as reported in teleost species. Besides, NO contributes through nervous stimulation to the regulation of vascular tone and blood circulation in the gill.

Animals↗
PubMed2005

Insulin regulates ionic metabolism in a fresh water teleost, anabas testudineus (bloch).

Short term effects of insulin on total brain and branchial Na+K+ ATPase, Ca2+ ATPase and Na+, K+ and Ca2+ ions were investigated in A. testudineus. The increase in brain Ca2+ ATPase after alloxan treatment may account for an increased amount of intracellular calcium required for biochemical events taking place inside the cells. Branchial Na+K+ATPase was significantly stimulated while Ca2+ ATPase significantly inhibited after alloxan treatment. This suggests that alloxan exerts its inhibitory effect on the ATP-driven Ca2+ transport via; its action on the Ca2+ pump protein rather than the membrane permeability to Ca2+. The increased activity of brain Na+K+ ATPase at 3 and 24 hr by insulin to alloxan pretreated fish may account for the stimulated co-transport of glucose and its utilization for energy requirements and the excitatory action on neurons in the brain. The elevated brain Ca2+ ATPase may be due to the role of calcium as a second messenger in hormone action. At 24 hr, the activity of branchial Na+K+ ATPase and Ca2+ ATPase in alloxan pretreated specimens was significantly stimulated by insulin. This may be due to increased synthesis of these enzyme units. Administration of insulin (lU/fish) in normal fish significantly inhibited the activity of brain and branchial Na+K+ ATPase while brain Ca2+ ATPase showed a stimulatory effect at 3 and 24 hr compared to control. Inhibition of total branchial Ca2+ ATPase activity by insulin may be due to increased Ca2+ concentration. Higher plasma glucose level in alloxan treated groups confirms the diabetic effect of alloxan. Insulin reverses this effect. The possible mechanism by which insulin controls Na+K+ ATPase activity appears to be tissue specific. The results seem to be the first report on the effect of insulin on ATPase activity in a teleost. These data are consistent with the hypothesis that insulin performs a role in hydro mineral regulation in freshwater teleosts.

Alloxan↗
PubMed2006

Damage due to parasites in Mediterranean teleosts.

Evaluation of damages by parasites in teleosts, even if underextimated in the past, is today one of the most used methods to understand the effective impact of a parasite on a certain ichtyc species. The damage caused by a parasite on the host could be classified into direct, with tissue changes, or indirect, with a decrease of the productive performances. Based on this, a preliminary difference could be traced distinguishing parasites that show a coevolution with their host species, characterized by a low damage, and those parasites that can occasionally infect new host species, showing a high degree of damage. In consideration of the damage, parasites can have different actions on the host: subtractive, irritative, mechanical, traumatic, toxic, dismetabolic, antigenic and foretic. Those parasites able to cause tissue changes must be furtherly classified considering the type of inflammation they evoke on tissues: ulcerous, catarral, haemorrhagic, necrotic and granulomatous. Some parasites are encysted in tissues without any host reaction. The fish response against parasite can be inflammatory, the most frequent, but also hyperplastic, metaplastic, neoplastic and immunitary. The paper goes through different tissue changes due to the main parasites of Mediterranean teleosts.

Animals↗
PubMed1990

A well defined spinocerebellar system in the weakly electric teleost fish Gnathonemus petersii. A tracing and immuno-histochemical study.

Long ascending fiber systems were investigated in the spinal cord of a teleost fish, Gnathonemus petersii. Concomitant results of Fink-Heimer degeneration tracing as well as CaBP28K immunohistochemical labelling demonstrate the existence of a well defined direct pathway from the very lowest spinal level to the caudal lobe of the cerebellum. HRP retrograde labelling shows that this pathway originates in a cellular column located in the most ventral part of the lateral column next to the lateral extremity of the ventral horn. From each spinal segment, the large axons of these cells gather and form a strip shaped tract at the periphery of the lateral column immediately dorsal to the cell column from which they originate. The spinal course of these fibers is ipsilateral; they give off a large number of collaterals to the lateral reticular nucleus. Bypassing the trigeminal motor nucleus, the lateral column tract courses dorsally to the paratrigeminal command associated nucleus between the lateral lemniscus and the nucleus preeminentialis and with a ventro-dorsally oriented large loop, turns in the caudal direction and penetrates into the cerebellar caudal lobe. Running caudally in the dorsal granular layer of the caudal lobe, it shifts more and more medially and crosses the midline whilst decussating with the contralateral tract on the dorsal margin of the molecular layer of the caudal lobe. Finally, the tract splits off and terminates throughout the granular layer of the caudal lobe. The main characteristics of this pathway are similar to those of the ventral spinocerebellar tract of higher vertebrates; it conveys information from all spinal levels directly to the contralateral cerebellum. However, it does not seem to receive direct synaptic input from the periphery, since projection of the dorsal root fibers appears to be limited to the dorsal ipsilateral half of the spinal cord. The appearance of such a pathway in a teleost fish is probably related to the existence of a well developed proprioceptive system in this species.

Animals↗
PubMed1991

[Long ascending fibers in the dorsal column of a teleost fish: a disynaptic pathway connecting sense organs to cerebellum].

In spite of the generally accepted opinion that long ascending proprioceptive and tactile fibers do not occur in the spinal dorsal columns of teleost fish, it was demonstrated with degeneration and axonal transport tracing methods that such dorsal column fibers exist in the teleost fish Gnathonemus petersii. These fibers are in fact common spinal afferent fibers originating in spinal ganglion cells. They connect the peripheral sense organs with the lateral funicular nuclei (Fl2) in which the dorsal column fibers terminate, directly through the dorsal columns. In contrast to the dorsal column nuclei of higher vertebrates, the Fl2 nuclei do not project to the diencephalic thalamus but to the caudal lobe and the second lobe (C2) of the corpus cerebelli. Thus, sense organs and cerebellum are connected by a disynaptic pathway. Since the caudal lobe projects directly to the electrosensory lobe, that is, to the target of electrosensory afferents, the presence of a disynaptic pathway in G. petersii suggests the existence of a proprioceptive control of the electrosensory input.

Afferent Pathways↗
PubMed1991

Extracellular matrix of connective tissues in the heads of teleosts.

The distribution of extracellular matrix molecules (chondroitin and keratan sulphates, type II collagen) is described in cranial connective tissues of teleosts. Hyaline cartilage was similar to that in mammals and usually contained all 3 molecules. The more cellular cartilages that are not normally present in mammals were more variable in composition. Scleral cartilage closely resembled hyaline cartilage, Zellknorpel in the gill filaments resembled it in some species but not in others, and elastic/cell-rich and hyaline-cell cartilages were unlike hyaline cartilage. These variations may be related to functional or developmental differences between the tissues. Bone and chondroid bone also varied in composition between species. Whilst both tissues contained chondroitin sulphate, bone contained type II collagen in 5 of the 12 species examined. This suggests that cartilage components are more widespread in teleost bone than has previously been shown. Type II collagen also occurred in dense connective tissues of some species. Notably, where this molecule was present in one of these tissues, it was present in all.

Animals↗
PubMed1990

Secretion of endogenous lithium in teleost kidneys as a probable reflection of Na+ and water secretion in their renal proximal tubules.

Unlike mammals with renal reabsorption of lithium (Li+), in freshwater and, particularly, marine teleosts net secretion of this trace element by kidneys was discovered. The ratio of Li+ natural concentration (measured by mass spectrometric isotope dilution technique) in urine to that in blood plasma--(U/P)Li--lies in the range 2-6 in the freshwater species and between 5 and 14 in marine species, i.e. as a rule it is essentially higher than the inulin concentration index (U/P)In. It is supposed that the in vivo observed lithium net secretion in whole kidney reflects and quantitatively estimates Na+ and water secretion in renal proximal tubules of teleosts.

Animals↗
PubMed1989

Cytochrome P450IA1 induction and localization in endothelium of vertebrate (teleost) heart.

Previous studies have shown that high levels of cytochrome P450 can occur in cardiac microsomes of vertebrates [Mol. Pharmacol. 21:517-526, (1982)]. Here we identify the dominant cardiac P450 in the marine fish scup as P450E, a teleost representative of P450IA1, and we describe its restricted cellular localization in the heart. Treatment of scup with beta-naphthoflavone produced an unusually strong (10-fold) induction of spectrally measured P450 in cardiac microsomes, with specific content reaching levels (0.5 nmol/mg) similar to those induced in scup liver. Microsomal ethoxyresorufin O-deethylase and aryl hydrocarbon hydroxylase activities, catalytic functions of scup P450E, were induced in parallel with P450 content. Similar induction was seen in both atrium and ventricle. Immunoblot analysis with monoclonal antibody 1-12-3, specific to scup P450E and other vertebrate P450IA1 proteins, showed that this hydrocarbon-inducible P450 is the dominant and possibly sole P450 form in heart microsomes of experimentally induced animals. Immunohistochemical analysis of scup heart sections (2-4-microns) with monoclonal antibody 1-12-3 revealed that P450E was detectable only in endothelial cells of the endocardium and of the coronary vasculature. A similar endothelial cell localization of the monoclonal antibody 1-12-3 epitope was observed in heart of rainbow trout, induced with beta-naphthoflavone, indicating a general nature for the endothelial localization of induced cardiac P450. Morphometric analysis showed that endothelium could constitute 8-9% of the volume of teleost heart, from which we calculate that P450IA1 could account for as much as 25% of the endothelial cell microsomal protein. Heart microsomes of untreated animals from contaminated environments also contained high levels of P450E, indicating that induction like that caused by beta-naphthoflavone could occur with chemicals in the environment. Strongly induced P450E (P450IA1) in endothelium could play a critical role in chemical-biological interactions involving xenobiotics affecting the vasculature of the heart or other organs.

Animals↗
PubMed1989

Neuroglia in the optic tectum of teleosts.

The morphology of the neuroglial cells of the optic tectum of Cyprinid teleosts (Cyprinus carpio and Barbus bocagei) was analyzed using two variants of the Golgi method (Colonnier and Meyer) and electron microscopy. Although the description of the results is based on the three classical neuroglial types (ependymocytes, astrocytes and oligodendrocytes), their analysis shows that the differentiation between astrocytes and oligodendrocytes is complex. Owing to the occurrence of numerous elements with intermediate characteristics, it is suggested that in Teleosts both glial types (astrocytes and oligodendrocytes) correspond to functional variants of a single cell type.

Animals↗
PubMedDate not supplied

Induction of monooxygenase activity in the intestine of spot (Leiostomus xanthurus), a marine teleost, by dietary polycyclic aromatic hydrocarbons.

The response of intestinal monooxygenases to dietary polycyclic aromatic hydrocarbon (PAH) exposure was evaluated in spot (Leiostomus xanthurus), a marine teleost fish. Ethoxyresorufin O-deethylase (EROD) and aryl hydrocarbon hydroxylase (AHH) activities were highest in the pyloric caeca and in the proximal half of the intestine. Intestinal microsomes from fish given control diets had very low levels of EROD and AHH activities relative to those in liver. After exposure to a diet containing 10 mg of 3-methylcholanthrene/kg of food, the levels of intestinal EROD and AHH activities increased 36-fold and 17-fold, respectively, such that intestinal monooxygenase activity exceeded that of the liver, which was not induced by this treatment. A significant increase in intestinal monooxygenase activity occurred in fish receiving dietary benzo[a]pyrene (BP) at concentrations as low as 10 micrograms of BP/kg food. A 5-fold increase in intestinal AHH and EROD activities was observed within 3 hr after administration of dietary BP. A plateau in gut monooxygenase activity occurred after approximately 3 days of PAH exposure; these activities decreased to control levels within 3 days after replacing the PAH diet with the control diet. Starvation resulted in disappearance of detectable monooxygenase activity. Monoclonal antibody (MAB 1-12-3) against the major PAH-inducible cytochrome P-450 (P-450E) in the liver of the marine teleost (Stenotomus chrysops) [Park et al. Arch. Biochem. Biophys. 249, 399 (1986)] recognized a single protein band in intestinal microsomes, with Mr near 54,000, which we conclude is the spot counterpart to cytochrome P-450E.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

The function of teleost fish lymphocytes in relation to inflammation.

Teleost fish exhibit inflammatory reactions which closely resemble those of mammals, but little is known about the mechanisms of inflammation in fish. While the leucocytes associated with inflammatory responses of fish bear close morphological similarity to those of mammals, it is not yet clear how comparable they are in function. Recently much work has been done to investigate the presence of lymphocyte subpopulations in fish, and while much of the data suggest the presence of mammalian T- and B-like lymphocytes the situation is still not clear and important differences appear to exist. Less information is available on the function of other inflammatory cell types, the neutrophils and macrophages, but once again differences between these cells in fish and mammals are apparent. The largest group of fish (the teleosts) comprises over 16,000 species which are widely evolved and differences between species should be expected and are indeed evident. Generalization concerning physiological responses of fish should therefore be made with caution.

Animals↗
PubMed1979

Gap junctions between microvilli of an oocyte and follicle cells in the teleost (Plecoglossus altivelis).

In the teleost, Plecoglossus altivelis, intercellular junctions between microvilli of an oocyte and follicle cells were studied by electron microscopy. Microvilli, which were radiated from an oocyte and arrived at the surface of follicle cells, established contact with follicle cells. These contact areas appeared to be a seven-layered membrane with an overall thickness of about 18 microns by standard fixation. In freeze-fracture replicas, many small aggregates of intramembraneous particles were revealed on the cleavage faces of cytoplasmic membranes of follicle cells. These morphological evidences suggest that in the teleost gap junctions exist between the oocyte and follicle cells, especially on the surface of follicle cells.

Animals↗
PubMed1979

[Histologic study of the teleost liver. I. The structure of the liver parenchyma].

The liver parenchyma of the teleosts investigated in this study does not show a true lobular pattern. The finer arrangement of the hepatocytes corresponds to the classical conception that the structure of the liver parenchyma is tubular. On the other hand the laminar structure of parenchyma (ELIAS), as it is often described in the more recent literature, must be regarded as a predominantly descriptive perspective. Remnants of a tubular structure also appear in the liver of the cyprinids investigated here, which have no real liver tubules owing to the special feature of the canalicular region (unicellular or "intracellular" bile canaliculi). Compared to the liver of higher vertebrates eight of the nine teleost species investigated here possess a liver poor in connective tissue. The liver of Haplochromis burtoni also lacks a continuous tissue layer beneath the peritoneal mesothelium. In contrast the liver of Tetraodon leiurus is characterized by an abundance of connective tissue. This phenomenon can be attributed to the high proportion of sinusoids in the parenchyma, which confers a structure similar to that of mammalian liver. The resulting loss of mechanical stability is obviously compensated for by the enlarged contribution of the connective tissue to the structure of the parenchyma.

Animals↗
PubMed1982

Phylogenetical development of somatostatin-containing cells in the retina from teleosts to mammals: immunohistochemical analysis.

The distribution of somatostatin (SRIF) in the retina of various vertebrates (from teleosts to mammals) was investigated by means of indirect immunohistochemical technique. The present study revealed that there exists marked differences in topography of SRIF-containing cell systems between higher vertebrates (birds and rats) and lower vertebrates (amphibian and teleosts). The retinas of the higher vertebrates contain abundant SRIF-positive structures, while those of the lower vertebrates contain a few. Phylogenetical development of retinal SRIF-system was briefly discussed in this study.

Animals↗
PubMed1981

Sacciform cells in the skin of teleost fish.

The fine structure of sacciform gland cells of the epidermis is described in the number of species of teleost fish. In some of these the cell type had either not been found, or not recognized as such, before. Some histological and histochemical results are also reported. Despite considerable differences in the histochemistry and in the morphology of the sacciform cells over the range of species studied, some features of the fine structure are constant and can be used as diagnostic characters. The nucleus is peripheral, and there is a large membrane-limited lumen, into which the secretion is released from membrane-bounded vacuoles at the margin of the cytoplasm. It is probable that the secretion originates mainly in channels of endoplasmic reticulum which become swollen to form the vacuoles. Most sacciform cells open at the surface of the skin by an apical pore, but some have not been seen to open. The classification of the various unicellular glands of teleosts is discussed and it is concluded that attempts to categorise them by the nature of the secretion alone are unsatisfactory.

Animals↗
PubMed1984

Calmodulin-binding proteins in teleost retina, rod inner and outer segments, and rod cytoskeletons.

125I-calmodulin gel overlay techniques have been used to identify calmodulin-binding proteins in teleost retina, in a rod fragment preparation which contains rod inner and outer segments (RIS-ROS), and in RIS-ROS cytoskeletons. We have previously shown that teleost rods change length in response to changes in light conditions, that rod movement is mediated by the actin filaments in the rod inner segment, and that both Ca2+ and cAMP appear to be involved in regulating rod movement. We report here the development of a rod fragment preparation (RIS-ROS), which retains the movable part of the rod, for use in biochemical analysis of rod motility. Gel overlay studies indicate that isolated whole retinas have six prominent calmodulin-binding proteins, migrating at 240 K, 190 K, 150 K, 61 K and a doublet at 18/19 K. In contrast, detached RIS-ROS have three different prominent calmodulin-binding proteins, migrating at 330 K, 33 K, and 31 K. RIS-ROS cytoskeletons have been produced by extraction with Triton X-100; they contain both actin filament bundles and microtubules associated with the connecting cilium. RIS-ROS cytoskeletons have 3 prominent calmodulin-binding proteins migrating at 240 and 18/19 K. These proteins produce faint bands in gel overlays of intact RIS-ROS, but prominent bands in overlays of whole retina. The 240 K protein of RIS-ROS cytoskeletons co-migrates with the 240 K calmodulin-binding subunit of rat brain fodrin. We suggest that the rod 240 K calmodulin-binding protein may be a spectrin-like protein which participates in Ca2+- and calmodulin-regulation of rod motility.

Animals↗