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At least 19 recordsLinked to original sources
PubMed1993

Molecular analysis of ependymins from the cerebrospinal fluid of the orders Clupeiformes and Salmoniformes: no indication for the existence of an euteleost infradivision.

Ependymins represent the predominant protein constituents in the cerebrospinal fluid of many teleost fish and they are synthesized in meningeal fibroblasts. Here, we present the ependymin sequences from the herring (Clupea harengus) and the pike (Esox lucius). A comparison of ependymin homologous sequences from three different orders of teleost fish (Salmoniformes, Cypriniformes, and Clupeiformes) revealed the highest similarity between Clupeiformes and Cypriniformes. This result is unexpected because it does not reflect current systematics, in which Clupeiformes belong to a separate infradivision (Clupeomorpha) than Salmoniformes and Cypriniformes (Euteleostei). Furthermore, in Salmoniformes the evolutionary rate of ependymins seems to be accelerated mainly on the protein level. However, considering these inconstant rates, neither neighbor-joining trees nor DNA parsimony methods gave any indication that a separate euteleost infradivision exists.

Amino Acid Sequence↗
PubMed1986

An apparent progressive and recurrent evolutionary restriction in tissue expression of a gene, the lactate dehydrogenase-C gene, within a family of bony fish (Salmoniformes: Umbridae)

Unexpectedly large differences in the tissue patterns of lactate dehydrogenase-C (Ldh-C) gene regulation were observed among species of fish within the family Umbridae (Salmoniformes). Normally, all the species within a family or order of advanced fishes exhibit the same, tissue-restricted pattern of L-lactate dehydrogenase C4 isozyme synthesis--either eye- or liver-restricted expression, but not both. However, within the Umbridae the more anciently derived species had a more generalized (primitive) tissue expression, whereas the more recently derived species had a more tissue-restricted expression, predominating in the eye. Given the relative divergence times among the species estimated by genetic distance (using 51 protein-coding loci), divergence from the presumed primitive expression of the Ldh-C gene appears to have been proceeding more rapidly in some species lineages than others. This narrowing of Ldh-C gene tissue regulatory specificity within the family Umbridae is similar to the general trend observed over much greater evolutionary times within the class of bony fishes. The results support the hypothesis of repeated evolutionary canalizations of Ldh-C gene regulation from the generalized tissue expression in more primitive species to a predictable tissue-restricted expression (in either eye or liver) in advanced species. Furthermore, in the Umbridae, this progressive restriction of tissue expression of isozymes has taken place during the evolution of both the Ldh-C and Ldh-B genes. These evolutionary trends in the regulation of isozyme-locus tissue expression in the bony fishes are consistent with either an intrinsically conditioned trend of change in gene regulation or with a response to natural selection.

Animals↗
PubMed2005

Cytogenetic analysis of three Italian populations of Coregonus lavaretus (Pisces, Salmoniformes) with chromosomal localization of major and minor ribosomal genes, and telomeric repeats.

The European whitefish, Coregonus lavaretus, widely distributed in freshwater of northern Europe and introduced into the major lakes of northern Italy, has been restocked in central Italian lakes. In accordance with current managing practices, a reduced number of spawners contribute to reproduction within each lake and a certain degree of isolation is to be expected between populations from different lakes, resulting in the rapid fixing of chromosomal changes. A detailed survey of three populations from different lakes was carried out using classical and molecular cytogenetic techniques, to verify if specific chromosomal markers are present in the distinct populations. The comparative analysis revealed intraspecific variability of NORs and fixed differences in their number in the three populations. A co-localization of major and minor rRNA genes on one chromosome site was also observed. The original data regarding the chromosome mapping of the (TTAGGG)(n) telomeric repeat obtained in this study, demonstrated their exclusively terminal distribution, and a conspicuous inter-chromosomal variation in the number of repeats. The results are compared with data available for populations from native geographic ranges.

Animals↗
PubMedDate not supplied

Infections by helminth parasites in "puyenes", Galaxias maculatus (Galaxiidae, Salmoniformes), from Southern Argentina with special reference to Tylodelphys barilochensis (Digenea, Platyhelminthes).

The occurrence of Tylodelphys barilochensis, Acanthostomoides apophalliformis, Contracaecum sp. and Camallanus corderoi infecting Galaxias maculatus ("puyenes") was quantified for the first time in Lake Nahuel Huapi, southern Argentina. T. barilochensis was recorded in this lake for the first time. The role of G. maculatus population in transmission of parasites to the salmonids is more important for Contracaecum sp. (prevalence 14-34%) and A. apophalliformis (prevalence 30-54%) than for C. corderoi (prevalence 6-8%). The absence of Diphyllobothrium spp. in samples shows that the G. maculatus population does not play any role in the life cycles of these important zoonotic parasites. The sex of the host had no effect on T. barilochensis abundance. Statistical differences in T. barilochensis abundance between "puyenes" of the same size class between sampling stations and positive correlation between prevalence of infected snails and T. barilochensis abundance in fish suggest that different stocks have been sampled. Factors influencing T. barilochensis abundance are discussed.

Animals↗
PubMed1996

Immunohistochemical and Ultrastructural characterization of the terminal nerve ganglion cells of the ayu, Plecoglossus altivelis (Salmoniformes, Teleostei).

BACKGROUND: Little is known on the cytological properties of the terminal nerve ganglion (TNG) cells in teleosts (Demski, 1993. Acta Anat., 148:81-95). MATERIALS AND METHODS: To characterize the TNG cells of a salmonoid fish, Plecoglossus altivelis, we adopted immunohistochemistry and transmission electron microscopy (TEM). RESULTS: The majority of the TNG cells formed a compact mass halfway between the olfactory sac and the olfactory bulb, whereas a few cells were scattered in the ventromedial region of the olfactory bulb. The cell had a voluminous perikaryon that was positive to antisera against gonadotropin-releasing hormone (GnRH), molluscan cardioexcitatory tetrapeptide (FM-RFamide), and neuropeptide Y (NPY). Immunostaining of consecutive sections with each antiserum showed the coexistence of these antigens in the same cells and their processes. Most of the processes originating from the cells projected centrally to the basal forebrain, including the optic nerve. With TEM, the cells revealed a peptidergic nature, i.e., the presence of abundant granular endoplasmic reticula and well-developed Golgi bodies in association with vesicles that were 70-100 nm in diameter. Occasionally, the cells adjoined one another directly without the intervention of glial sheets. Synaptic contacts were frequent in the proximal region of the processes, where thin lateral processes of the cells and axon terminals of unknown origin were intermingled with each other. Terminal buttons being engulfed by the soma were commonly seen. CONCLUSIONS: The TNG cells of the salmonoid fish share many cytological characteristics with the cells of the nucleus olfactoretinalis of advanced teleosts such as acanthopterygians.

Animals↗
PubMed2004

Chromosome banding studies by replication and restriction enzyme treatment in vendace (Coregonus albula) (Salmonidae, Salmoniformes).

Chromosome banding studies were performed in vendace, Coregonus albula. Original data on distribution of early and late replication regions, restriction sites (AluI, DdeI, HinfI and HaeIII) on chromosomes in this coregonid fish have been used to analyse karyotype heterochromatin differentiation. Heterochromatic bands (C-positive and not digested by restriction enzymes) have been identified as late replicating regions. Extra bands produced by the applied methods have permitted the identification of several homologous pairs. The centromeres were differentially digested by the restriction enzymes. The studied population seems to be homogenic regarding karyotype characteristics.

Animals↗
PubMedDate not supplied

[A preliminary study of parasite diversity in the anadromous Kamchatkan mikizha Parasalmo mykiss mykiss (Osteichthyes: Salmoniformes: Salmonidae)].

The study of parasites associated with the anadromous mikizha from several rivers of the Western Kamchatka has revealed 44 parasite species. The majority of parasites (59%) belong to marine and estuarine-marine species. Lecithophyllum bothryophorum, Echinorhynchus leidyi and plerocercoids of the family Litobothriidae were found for the first time in anadromous fish entering into Asian continental watersheds. It has been revealed that only a few specimens of the anadromous mikizha feed in fresh waters. Most of feeding fish consume a minor amount of food, and this feeding is occasional. Young forms of intestinal parasites of the freshwater and estuarine-freshwater groups (Neoechinorhynchus spp., Crepidostomum spp., Cucullanus truttae, Eubothrium salvelinf) come into anadromous fishes mainly before their entering in fresh waters.

Acanthocephala↗
PubMedDate not supplied

[Reproduction and average size at maturity of the trout Oncorphynchus mykiss (Salmoniformes:Salmonidae) in the Venezuelan Andes)].

From January 1987 to February 1988, a total of 393 rainbow trout were captured in a high mountain stream of the Venezuelan Andes (8 degrees 40'N; 71 degrees 5'W). Gonadal development was measured using the Nikolsky method. The mean size for sexual maturation was analyzed with the method of relative frequency of adults and young for each size class. Males reproduced throughout the year, while ripe females were observed only in January (11%). A half of the males was sexually mature at the minimum size of 13.40 cm SL (16.25 for females). All individuals were sexually mature at 26.40 cm (males) and 26.80 cm (females).

Animals↗
PubMed1994

[Food habits of the rainbow trout Oncorhynchus mykiss (Salmoniformes: Salmonidae) in an Andean creek of Venezuela].

Monthly stomach context samples of rainbow trout from Mucunután stream (Mérida, Venezuela), were collected from, March 1987 to February 1988 (n = 306). The major dietary components were Ephemeroptera, Trichoptera and Diptera. Baetodes sp. was the most important food item based on numerical composition (43%) and frequency of occurrence (88%). When the gravimetric method was used Leptonema sp. was the major dietary component. The diet was not a function of sex. The consumed fauna was more similar to the drift invertebrate fauna than to that of benthos (p < 0.01). The fluctuations on the stomach content paralleled changes of food availability in the environment.

Animals↗
PubMed1997

Adrenocortical and adrenomedullary homologs in eight species of adult and developing teleosts: morphology, histology, and immunohistochemistry.

Morphology, histology, and immunohistochemistry of the adrenocortical and adrenomedullary homologs (adrenal glands) of the following developing and adult teleosts were examined: Salmoniformes-Oncorhynchus mykiss (rainbow trout), Salmo trutta fario (brown trout), Coregonus lavaretus (white fish); Cyprinodontiformes-Gambusia affinis (mosquito fish). Perciformes-Dicentrarchus labrax (sea bass), Sparus aurata (sea bream), Diplodus sargus (white bream), Oblada melanura (saddled bream). The anatomical relationships of the gland with the renal system and venous vessels were also noted. In adults of all species steroidogenic and catecholaminergic chromaffin cells were found in the head kidney, which is pronephric in origin and subsequently transformed into a hematopoietic lymphatic organ. In Perciformes, chromaffin cells are distributed around the anterior and posterior cardinal veins and ducts of Cuvier; in Salmoniformes, around the posterior cardinal veins and in the hematopoietic tissue; and in G. affinis, around the ducts of Cuvier and posterior cardinal veins, while a few are visible also around the sinus venosus. In Perciformes and Salmoniformes, numerous chromaffin cells are also present in the posterior kidney, derived from the opisthonephros, in contact with the caudal vein. Steroidogenic cells are always confined to the head kidney. During development chromaffin and steroidogenic cells appear early after hatching in the pronephric kidney, at the level of the ducts of Cuvier and of the cephalic part of the posterior cardinal veins. Later, chromaffin cells in Perciformes reach the anterior cardinal veins, and subsequently, in both Perciformes and Salmoniformes, they reach the developing posterior kidney. Their localization along the posterior kidney is still in progress about 4 months after hatching and is completed about a year after hatching. These findings support the concept that the structure of the adrenal gland in teleosts is intermediate between that of the other actinopterygians and that of tetrapods. The development differs from that of tetrapods in that it occurs mainly in the pronephros and only later do chromaffin cells reach the opisthonephric kidney.

3-Hydroxysteroid Dehydrogenases↗
PubMed1980

Structural evidence for two different testicular types in teleost fishes.

Testicular structure in Salmoniformes, Perciformes, Cypriniformes, and Atheriniformes has been examined and reinterpreted on the basis of two different tubular types, distinguished from each other by the intratubular distribution of spermatogonia. In the salmoniform, perciform, and cypriniform teleosts studied, spermatogonia are distributed along the entire length of the testicular tubules. However, in the atheriniform teleosts spermatogonia are restricted to the distal end of the tubule. Sperm development in teleosts is cystic, cysts being comprised of Sertoli-cell processes. In both testicular types described, Sertoli cells phagocytize spermatid residual bodies. Together with the germ cells, they comprise the only intratubular cell types within the teleostean testis. Boundary cells are located immediately outside of the tubule basement membrane. They do not form a complete layer over the tubule surface; therefore, interstitial Leydig cells and blood vessels may border directly upon the tubular basement membrane.

Animals↗
PubMed2006

Karyotype and chromosomal characteristics of Ag-NOR sites and 5S rDNA in European smelt, Osmerus eperlanus.

Karyotype and cytogenetic characteristics of European smelt Osmerus eperlanus were investigated using different staining techniques (sequential Ag-, CMA3 and DAPI banding) and PRINS to detect 5S rDNA and telomeric sites. The diploid chromosome number was invariably 2n = 56 and karyotype composed of 5 pairs of metacentrics, 9 pairs of subtelocentrics and 14 pairs of subtelo- to acrocentrics. The DAPI-positive heterochromatic regions were found in centromeric positions on bi-armed chromosomes and few acrocentrics. Additionally, some interstitial DAPI-positive bands were identified on three pairs of submetacentric chromosomes. The nucleolar organizer regions (NORs) were detected in the short (p) arms of the largest metacentric pair of chromosomes No. 1. Sequential banding (Giemsa-, AgNO(3) and CMA(3) stainings) revealed NOR sites corresponding to achromatic regions but not associated with CMA(3)-positive blocks of heterochromatin located on either side of NORs. Individuals from the analyzed population had this conspicuous pair of chromosomes always in heterozygous combination. A complex inversion system was hypothesized to be involved in the origin of the observed variation but analysis with telomeric PRINS and PNA-FISH did not reveal any Interstitial Telomeric Sites (ITS). Hybridization signals were confined exclusively to terminal chromosomal regions. The 5S ribosomal sites as revealed by PRINS were found to be invariably located in the short (p) arms of four pairs of subtelocentric chromosomes. Cytotaxonomic comparisons of the present results with the voluminous available cytogenetic data-set from salmoniform and esociformes fishes appear to support the recent view, based on robust molecular-based phylogeny, that salmoniform and osmeriform fishes are not as closely related as previously assumed.

Animals↗
PubMed1999

Cloning of a neoteleost (Oreochromis mossambicus) pro-opiomelanocortin (POMC) cDNA reveals a deletion of the gamma-melanotropin region and most of the joining peptide region: implications for POMC processing.

A signature feature of tetrapod pro-opiomelanocortin (POMC) is the presence of three melantropin (MSH) coding regions (alpha-MSH, beta-MSH, gamma-MSH). The MSH duplication events occurred early during the radiation of the jawed vertebrates well over 400 million years ago. However, in at least one order of modern bony fish (subdivision Teleostei; order Salmoniformes; i.e. salmon and trout) the gamma-MSH sequence has been deleted from POMC. To determine whether the gamma-MSH deletion has occurred in other teleost orders, a POMC cDNA was cloned from the pituitary of the neoteleost Oreochromis mossambicus (order Perciformes). In O. mossambicus POMC, the deletion is more extensive and includes the gamma-MSH sequence and most of the joining peptide region. Because the salmoniform and perciform teleosts do not share a direct common ancestor, the gamma-MSH deletion event must have occurred early in the evolution of the neoteleost fishes. The post-translational processing of O. mossambicus POMC occurs despite the fact that the proteolytic recognition sequence, (R/K)-Xn-(R/K) where n can be 0, 2, 4, or 6, a common feature in mammalian neuropeptide and polypeptide hormone precursors, is not present at several cleavage sites in O. mossambicus POMC. These observations would indicate that either the prohormone convertases in teleost fish use distinct recognition sequences or vertebrate prohormone convertases are capable of recognizing a greater number of primary sequence motifs around proteolytic cleavage sites.

Amino Acid Sequence↗