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At least 199 records · Page 11Linked to original sources
PubMed2003

Characterisation of intestinal peptide transporter of the Antarctic haemoglobinless teleost Chionodraco hamatus.

H(+)/peptide cotransport was studied in brush-border membrane vesicles (BBMV) from the intestine of the haemoglobinless Antarctic teleost Chionodraco hamatus by monitoring peptide-dependent intravesicular acidification with the pH-sensitive dye Acridine Orange. Diethylpyrocarbonate-inhibited intravesicular acidification was specifically achieved in the presence of extravesicular glycyl-L-proline (Gly-L-Pro) as well as of glycyl-L-alanine (Gly-L-Ala) and D-phenylalanyl-L-alanine (D-Phe-L-Ala). H(+)/Gly-L-Pro cotransport displayed saturable kinetics, involving a single carrier system with an apparent substrate affinity (K(m,app)) of 0.806+/-0.161 mmol l(-1). Using degenerated primers from eel and human (PepT1) transporter sequence, a reverse transcription-polymerase chain reaction (RT-PCR) signal was detected in C. hamatus intestine. RT-PCR paralleled kinetic analysis, confirming the hypothesis of the existence of a PepT1-type transport system in the brush-border membranes of icefish intestine. Functional expression of H(+)/peptide cotransport was successfully performed in Xenopus laevis oocytes after injection of poly(A)(+) RNA (mRNA) isolated from icefish intestinal mucosa. Injection of mRNA stimulated D-Phe-L-Ala uptake in a dose-dependent manner and an excess of glycyl-L-glutamine inhibited this transport. H(+)/peptide cotransport in the Antarctic teleost BBMV exhibited a marked difference in temperature optimum with respect to the temperate teleost Anguilla anguilla, the maximal activity rate occurring at approximately 0 degrees C for the former and 25 degrees C for the latter. Temperature dependence of icefish and eel intestinal mRNA-stimulated uptake in the heterologous system (oocytes) was comparable.

Amino Acid Sequence↗
PubMed2001

Pathways for urea production during early life of an air-breathing teleost, the African catfish Clarias gariepinus Burchell.

Embryos and larvae of the African catfish Clarias gariepinus excrete significant quantities of urea. The present study focused on the potential urea-generating pathways during early development of this teleost; uricolysis, argininolysis and the ornithine-urea cycle (OUC). Uricase, allantoinase, allantoicase and ureidoglycollate lyase of the uricolytic pathway were expressed in all early life stages and in adult liver of C. gariepinus. Uricase activity increased in starved larvae compared with yolk-sac larvae. The key regulatory enzyme of the teleost OUC, carbamoyl phosphate synthetase III (CPSase III), was expressed predominantly in muscle of developing C. gariepinus larvae and showed negligible activity in the absence of its allosteric effector N-acetyl-L-glutamate. CPSase III and ornithine carbamoyl transferase activities increased in fed larvae compared with starved larvae. In contrast to the early developmental stages, adult C. gariepinus expressed only low and variable levels of CPSase III, suggesting that, under the experimental conditions employed, OUC expression is influenced by developmental stage in this species. The data indicate that early C. gariepinus life stages express the enzymes necessary for urea production by uricolysis, argininolysis and the OUC, and this may explain why urea tissue levels and urea excretion rates are substantial during the early development of this air-breathing teleost.

Air↗
PubMed2001

Expression of pineal ultraviolet- and green-like opsins in the pineal organ and retina of teleosts.

In teleostean bony fishes, studies on the adults of various species have shown that pineal photoreceptors are maximally sensitive to short- and middle-wavelength light, possibly utilising both rod-like and pineal-specific opsins. Until recently, however, very little was known about the pineal opsins present in embryonic and larval teleosts and their relationships to opsins expressed by retinal photoreceptors. Our immunocytochemical studies have revealed that, in Atlantic halibut, herring and cod, pineal photoreceptors express principal phototransduction molecules during embryonic life before they appear in retinal photoreceptors. In cDNA from embryonic and adult halibut, we identified two partial opsin gene sequences, HPO1 and HPO4, with highest homology to teleost green and ultraviolet cone opsins (72-83% and 71-83% amino acid identity, respectively). In halibut, these opsins are expressed in the pineal organ of embryos and appear in the retina of larvae. Our recent in situ hybridisation studies with RNA probes for HPO1 and HPO4 demonstrate the presence of green-like opsin mRNAs in the pineal organ and the retina of herring, cod, turbot, haddock, Atlantic salmon, zebrafish and three species of cichlid, and of ultraviolet opsins in the retinas of zebrafish, Atlantic salmon, turbot and the three cichlid species. We conclude that the halibut pineal organ appears to have the potential for both ultraviolet and green photosensitivity from the embryonic stage and that the retina may acquire the same potential during the larval stages. In the other teleosts studied, although both pineal and retinal photoreceptors seem to utilise a green-like opsin from the larval stage, ultraviolet photoreception appears to be restricted to the retina.

Animals↗
PubMed2002

Olfactory sensitivity to changes in environmental [Ca(2+)] in the freshwater teleost Carassius auratus: an olfactory role for the Ca(2+)-sensing receptor?

Olfactory sensitivity to changes in environmental Ca(2+) has been demonstrated in two teleost species; a salmonid (Oncorhynchus nerka) and a marine/estuarine perciform (Sparus aurata). To assess whether this phenomenon is restricted to species that normally experience large fluctuations in external ion concentrations (e.g. moving from sea water to fresh water) or is present in a much wider range of species, we investigated olfactory Ca(2+) sensitivity in the goldfish (Carassius auratus), which is a stenohaline, non-migratory freshwater cyprinid. Extracellular recording from the olfactory bulb in vivo by electroencephalogram (EEG) demonstrated that the olfactory system is acutely sensitive to changes in external Ca(2+) within the range that this species is likely to encounter in the wild (0.05-3 mmol l(-1)). The olfactory system responded to increases in external calcium with increasing bulbar activity in a manner that fitted a conventional Hill plot with an apparent EC(50) of 0.9+/-0.3 mmol l(-1) (close to both ambient and plasma free [Ca(2+)]) and an apparent Hill coefficient of 1.1+/-0.3 (means +/- S.E.M., N=6). Thresholds of detection were below 50 micro mol l(-1). Some olfactory sensitivity to changes in external [Na(+)] was also recorded, but with a much higher threshold of detection (3.7 mmol l(-1)). The olfactory system of goldfish was much less sensitive to changes in [Mg(2+)] and [K(+)]. Preliminary data suggest that Ca(2+) and Mg(2+) are detected by the same mechanism, although with a much higher affinity for Ca(2+). Olfactory sensitivity to Na(+) may warn freshwater fish that they are reaching the limit of their osmotic tolerance when in an estuarine environment. Olfaction of serine, a potent odorant in fish, was not dependent on the presence of external Ca(2+) or Na(+). Finally, the teleost Ca(2+)-sensing receptor (Ca-SR) was shown to be highly expressed in a subpopulation of olfactory receptor neurones by both immunocytochemistry and in situ hybridisation. The olfactory sensitivity to Ca(2+) (and Mg(2+)) is therefore likely to be mediated by the Ca-SR. We suggest that olfactory Ca(2+) sensitivity is a widespread phenomenon in teleosts and may have an input into the physiological mechanisms regulating internal calcium homeostasis.

Animals↗
PubMed1979

Respiratory gas exchange in the resting starry flounder, Platichthys stellatus: a comparison with other teleosts.

A wide range of respiratory, ventilatory, and cardiovascular parameters have been recorded under completely resting conditions in the starry flounder (Platichthys stellatus), a generally inactive benthic teleost. The results differ in a number of important respects from those of a previous study on the same species. The present data have also been compared with those reported for the active pelagic rainbow trout (Salmo gairdneri) and for other teleost species. Of particular note in the flounder, relative to the trout, are low arterial and venous PO2's, a low arterial-venous O2 content difference, a low transfer factor and high diffusion gradient for O2 across the gills, a high in vivo blood O2 affinity, a high cardiac output and stroke volume accompanied by a low peripheral vascular resistance, a low ventilation volume, a low ventilation-perfusion ratio, and a low capacity-rate ratio for O2 exchange at the gills. Parameters of CO2 transport and acid-base regulation appear conventional, though blood CO2 contents and lactate concentrations are low. The respiratory strategies of inactive versus active, and benthic versus pelagic teleosts are discussed.

Acid-Base Equilibrium↗
PubMed2003

Purification of matrix Gla protein from a marine teleost fish, Argyrosomus regius: calcified cartilage and not bone as the primary site of MGP accumulation in fish.

Matrix Gla protein (MGP) belongs to the family of vitamin K-dependent, Gla-containing proteins, and in mammals, birds, and Xenopus, its mRNA was previously detected in extracts of bone, cartilage, and soft tissues (mainly heart and kidney), whereas the protein was found to accumulate mainly in bone. However, at that time, it was not evaluated if this accumulation originated from protein synthesized in cartilage or in bone cells because both coexist in skeletal structures of higher vertebrates and Xenopus. Later reports showed that MGP also accumulated in costal calcified cartilage as well as at sites of heart valves and arterial calcification. Interestingly, MGP was also found to accumulate in vertebra of shark, a cartilaginous fish. However, to date, no information is available on sites of MGP expression or accumulation in teleost fishes, the ancestors of terrestrial vertebrates, who have in their skeleton mineralized structures with both bone and calcified cartilage. To analyze MGP structure and function in bony fish, MGP was acid-extracted from the mineralized matrix of either bone tissue (vertebra) or calcified cartilage (branchial arches) from the bony fish, Argyrosomus regius, separated from the mineral phase by dialysis, and purified by Sephacryl S-100 chromatography. No MGP was recovered from bone tissue, whereas a protein peak corresponding to the MGP position in this type of gel filtration was obtained from an extract of branchial arches, rich in calcified cartilage. MGP was identified by N-terminal amino acid sequence analysis, and the resulting protein sequence was used to design specific oligonucleotides suitable to amplify the corresponding DNA by a mixture of reverse transcription-polymerase chain reaction (RT-PCR) and 5'rapid amplification of cDNA (RACE)-PCR. In parallel, ArBGP (bone Gla protein, osteocalcin) was also identified in the same fish, and its complementary DNA cloned by an identical procedure. Tissue distribution/accumulation was analyzed by Northern blot, in situ hybridization, and immunohistochemistry. In mineralized tissues, the MGP gene was predominantly expressed in cartilage from branchial arches, with no expression detected in the different types of bone analyzed, whereas BGP mRNA was located in bone tissue as expected. Accordingly, the MGP protein was found to accumulate, by immunohistochemical analysis, mainly in the extracellular matrix of calcified cartilage. In soft tissues, MGP mRNA was mainly expressed in heart but in situ hybridization, indicated that cells expressing the MGP gene were located in the bulbus arteriosus and aortic wall, rich in smooth muscle and endothelial cells, whereas no expression was detected in the striated muscle myocardial fibers of the ventricle. These results show that in marine teleost fish, as in mammals, the MGP gene is expressed in cartilage, heart, and kidney tissues, but in contrast with results obtained in Xenopus and higher vertebrates, the protein does not accumulate in vertebra of non-osteocytic teleost fish, but only in calcified cartilage. In addition, our results also indicate that the presence of MGP mRNA in heart tissue is due, at least in fish, to the expression of the MGP gene in only two specific cell types, smooth muscle and endothelial cells, whereas no expression was found in the striated muscle fibers of the ventricle. In light of these results and recent information on expression of MGP gene in these same cell types in mammalian aorta, it is likely that the levels of MGP mRNA previously detected in Xenopus, birds, and mammalian heart tissue may be restricted to regions rich in smooth muscle and endothelial cells. Our results also emphasize the need to re-evaluate which cell types are involved in MGP gene expression in other soft tissues and bring further evidence that fish are a valuable model system to study MGP gene expression and regulation.

Amino Acid Motifs↗
PubMed2004

The retinal pigment epithelium of the teleost Notopterus notopterus (Pallas): appearance of basal infoldings during prolonged dark-adaptation.

In teleosts, the basal part of the retinal pigment epithelium (RPE) is relatively smooth, i. e., it is free of basal membrane infoldings. In the featherback, Notopterus notopterus, whereas this is the situation in light adaptation, during dark-adaptation, especially when kept for prolonged periods (6-9 hour), numerous infoldings appear at the basal region, as found uniquely by transmission electron microscopy. In this teleost, during retinomotor movements, the rods move vitreally during dark-adaptation, while the cones do not elongate, and remain stationary in both light- and dark-adaptation. The significance of the appearance of basal infoldings in dark-adapted RPE is explained in terms of the pattern of retinomotor responses and the features of RPE and photoreceptors in this species. It is suggested that (1) the thick, impervious tapetal layer present in the RPE, (2) the unusual position of the photoreceptors in the visual cell layer of dark-adapted retina, and (3) the presumably high demand for glucose and O2 of the outer retina during dark-adaptation might contribute to cause this phenomenon in this species. The available evidence tend to associate this phenomenon with the involvement of the RPE in nutrient and O2 delivery to the photoreceptors via the basal infoldings of the RPE in dark-adapted state in this species. This has not been reported for any other teleosts to date.

Animals↗
PubMed2003

Major histocompatibility lineages and immune gene function in teleost fishes: the road not taken.

It has become increasingly clear over the course of the past decade that the immune system genes of teleosts and tetrapods are plainly derived from common ancestral genes. The last 5 years, however, have also made it abundantly clear that in the teleost genome some of these genes are organized in a manner very different from that seen in mammals. These differences are probably the result of differences in life history traits, such as fecundancy, within each group of species when faced with an evolutionary fork in the road shortly after their divergence from each other. One group, the tetrapods, including mammals, chose a highly organized linked major histocompatibility complex, while in teleosts the major histocompatibility genes remained unlinked. In this review we will discuss the structural and functional implications of this different organization, particularly for major histocompatibility genes, but drawing on the current knowledge of some other genes for further support for the hypothesis that each group took a different road, one more traveled and one less taken.

Alleles↗
PubMed2001

Molecular cloning and characterization of thyroid hormone receptors in teleost fish.

Thyroid hormones are pleiotropic factors important for many developmental and physiological functions in vertebrates. Their effects are mediated by two specific receptors (TRalpha and TRbeta) which are members of the nuclear hormone receptor superfamily. To clarify the function of these receptors, our laboratory has started a comparative study of their role in teleost fish. This type of approach has been hampered by the isolation of specific clones for each fish species studied. In this report, we describe an efficient reverse transcription/PCR procedure that allows the isolation of large fragments corresponding to TRalpha and TRbeta of a wide range of teleost fish. Phylogenetic analysis of these receptors revealed a placement consistent with their origin, sequences from teleost fish being clearly monophyletic for both TRalpha and TRbeta. Interestingly, this approach allowed us to isolate (from tilapia and salmon) several new TRalpha or TRbeta isoforms resulting from alternative splicing. These isoforms correspond to expressed transcripts and thus may have an important physiological function. In addition, we isolated a cDNA encoding TRbeta in the Atlantic salmon (Salmo salar) encoding a functional thyroid hormone receptor which binds specific thyroid hormone response elements and regulates transcription in response to thyroid hormones.

Alternative Splicing↗
PubMed1976

Renin, cortisol and plasma volume in marine teleost fishes adapted to dilute media.

The renin-angiotensin system has been found in teleost fishes from both marine and fresh-water environments. In an attempt to define whether activity of the renin-angiotensin system is related to sodium balance in fishes, we transferred two euryhaline teleosts from seawater to hypo-osmotic media. Plasma renin activity decreased in American eels, Anguilla rostrata, after they were transferred from seawater to fresh water, and it did not change in the aglomerular toadfish, Opsanus tau, after transfer from 50% seawater to 5% seawater. Plasma sodium concentrations decreased significantly in toadfish in 5% seawater and in one group of eels in fresh water. Plasma levels of cortisol, a major mineralocorticoid in teleosts, and plasma volume, measured in eels, remained relatively constant. There are no clear correlations between plasma renin levels and those of plasma sodium or plasma cortisol. These results provide no evidence that the need of these fishes to conserve sodium when in hypo-osmotic media stimulates the renin-angiotensin system.

Adaptation, Physiological↗
PubMed2004

Comparative histological study of teleost livers in relation to phylogeny.

This report presents a detailed description of hepatic architecture in 200 teleost livers by light microscopy and extensively discusses the phylogenetic viewpoint. The 200 teleost livers showed a great variety of histological images, but not the same image, as in mammalian livers. The hepatocyte-sinusoidal structures of the fish livers were classified into three different types: (a) cord-like form, (b) tubular form, (c) solid form. Biliary tract structures were classified into four types: (a) isolated type, (b) biliary-arteriolar tract (BAT) type, (c) biliary-venous tract (BVT) type, and (d) portal tract type. As phylogenic advancement is graded from low to high, the parenchymal arrangement progressed from solid or tubular form to cord-like form, but the biliary tract structures were not involved. We demonstrate that this study is the first to investigate teleost livers phylogenically, and their architectural differences are shown in the route of hepatic ontogenesis. In hepatic ontogenesis, the formation of the parenchymal arrangement is acquired phylogenically, but the biliary pathway may be adapted in the ecological and behavioral patterns.

Animals↗
PubMed2000

Immunocytochemical identification and localization of APUD cells in the gut of seven stomachless teleost fishes.

AIM:To study the cell types, localization, distribution density and morphology of APUD cells in the intestinal mucosa of stomachless teleost fishes.METHOD:By using the peroxidase antiperoxidase complex (PAP) immunocytochemical staining technique the identification, localization and morphology of immunoreactive (IR) endocrine cells seattered in the intestinal mucosa of grass carp (Cyenopharyngodon idellus), black carp ( Mylopharyngodon piceus ) and common carp (Cyprinus carpio) were investigated with 20 kinds of antisera prepared against mammalian peptide hormones of APUD cells, and likewise by using avidin-biotin-peroxidase complex (ABC) method those of silver carp (Hypophthalmichthys molitrix), bighead (Aristichthys nobilis), silver crucian carp (Carassius gibelio) and bluntnose black bream (Megalobrama amblyocephala ) were also studied with 5 different antisera. The replacement of the first antiserum by phosphate buffered saline (PBS) was employed as a control. IR endocrine cells were counted with a square-mesh ocular micrometer from 10 fields selected randomly in every section of each part of the intestine specimen. The average number of IR endocrine cells per mm(2) was counted to quantify their distribution density.RESULT:Gastrin (GAS), Gastric inhibitory peptide (GIP), glucagon (GLU), glucagons like immunorea-ctants (GLI), bovine pancreatic polypeptide (BPP), leucine-enkephalin (ENK) and substance P (SP)-IR endocrine cells were found in the gut of grass carp, black carp and common carp, and somatostatin (SOM) IR endocrine cells were only seen in common carp. GAS, GIP and GLU-IR endocrine cells were found in the intestinal mucosa of silver carp, bighead, silver crucian carp and bluntnose black bream. Most of IR endocrine cells had the higher distribution density in the foregut and midgut, and were longer in shape. They had a long apical cytoplasmic process extended to the gut lumen and a basal process extended to adjacent cells or basement membrane and touched with it. Sometimes, the basal cytoplasmic process formed an enlarged synapse-like structure in the contiguous part with basement membrane. This phenomenon provided new morpho-logical evidence for neuroendocrine and paracrine secretory function of these enteroendocrine cells.CONCLUTION:At least 8 kinds of IR endocrine cells were found in the gut of stomachless teleost species for the first time in China. These IR endocrine cells scattering in the gut mucosa belong to the APUD system. Among them, the hormones secreted by SP-, ENK-, SOM- and GLU-IR endocrine cells belong to the peptides of dual distribution in the brain and gut. This provided new evidence for the concept of brain-gut peptide. According to the cell types, distribution density, morphological characteristics and variety in shape of APUD cells in the gut of stomachless teleost fishes, it is deemed that the digestive tract of fishes is also an endocrine organ of great importance and complexity.

Journal Article↗
PubMed1976

Effects of cold-shock on blood cells in a fresh water tropical teleost, Colisa fasciatus.

Immersion of the adult female fresh water tropical teleost, Colisa fasciatus, in ice water at c. 2 degrees C for one minute immobilizes the fish. It, however, recovers within two minutes when returned to warm temperature. Hematological studies at recovery time intervals, viz., 3, 15 and 27 min and, later, at intervals of 48 min up to 363 min, and at 12 and 24 h, revealed significant changes in the abundance of leucocytes and thrombocytes: an increase in the number of leucocytes (leucocytosis) was evident from 15 through 123 min and at 267 min; normal leucocyte counts, were observed at 3, 171, 219, 315 and 363 min, and at 12 h and 24 h. Lymphocytes are the major leucocyte cell type in the blood. Thrombocytopenia occurred at 15 and 27 min, and thrombocyte counts were held at normal levels at other recovery time intervals. There was no change in the abundance of erythrocytes in response to the imposed stress. Shock susceptibility of the fish for variables measured was similar in experiments performed during six different months of one calendar year. In addition, no significant seasonal or diurnal changes were recorded in the abundance of circulating blood cells. The results reported here, for the first time on a tropical teleost, do not agree with previous results obtained from temperate teleosts by other workers.

Animals↗
PubMed2001

Anatomical distribution and cellular basis for high levels of aromatase activity in the brain of teleost fish: aromatase enzyme and mRNA expression identify glia as source.

Although teleost fish have higher levels of brain aromatase activity than any other vertebrate group, its function remains speculative, and no study has identified its cellular basis. A previous study determined aromatase activity in a vocal fish, the plainfin midshipman (Porichthys notatus), and found highest levels in the telencephalon and lower levels in the sonic hindbrain, which was dimorphic between and within (males) sexes. We have now localized aromatase-containing cells in the midshipman brain both by immunocytochemistry using teleost-specific aromatase antibodies and by in situ hybridization using midshipman-specific aromatase probes. Aromatase-immuno-reactivity and mRNA hybridization signal are consistent with relative levels of aromatase activity in different brain regions: concentrated in the dimorphic sonic motor nucleus, in a band just beneath the periaqueductal gray in the midbrain, in ventricular regions in the hypothalamus, and highest levels in the telencephalon especially in preoptic and ventricular areas. Surprisingly, double-label immunofluorescence does not show aromatase-immunoreactive colocalization in neurons, but instead in radial glia throughout the brain. This is the first study to identify aromatase expression mostly, if not entirely, in glial cells under normal rather than brain injury-dependent conditions. The abundance of aromatase in teleosts may represent an adaptation linked to continual neurogenesis that is known to occur throughout an individual's lifetime among fishes. The localization of aromatase within the intersexually and intrasexually dimorphic vocal-motor circuit further implies a function in the expression of alternative male reproductive phenotypes and, more generally, the development of natural, individual variation of specific brain nuclei.

Animals↗
PubMedDate not supplied

PCNA positivity in the mesencephalic matrix areas in the adult of a Teleost, Carassius carassius L.

Adult Teleosts still display karyokinetic activity involving also the central nervous system so that physiological neurogenesis does not cease when adult body size is reached but later. In the brain this is due to the persistence in several districts of neural type elements in the ependymal epithelium or in the area surrounding it, which combine to form matrix zones or matrix areas. These elements may undergo proliferative and/or maturational events, including also post-traumatic neurogenic events, either natural or experimentally induced, as a result of which the degree of brain plasticity is inferior only to that observed in the Amphibians. As part of our project of re-examining the matrix areas of normal adult heterothermic Vertebrates based on the use of a recent proliferative marker displaying the expression of the Proliferating Cellular Nuclear Antigen (PCNA). This is a reliable immunocytochemical test owing to its role in the cell cycle and to the ubiquity of PCNA due to the theoretical basis of the method, has now been applied to the mesencephalon of the Teleosts, which is the location of matrix areas that are absent in the Amphibians and Reptiles. The immunocytochemical patterns we observed in Carassius carassius displayed a much strong DNA synthesis activity than that we found in the telencephalon of the same specimens. These spontaneous neurogenic manifestations are not limited to the optic tectum, and are not restricted to the already well-known caudal, ventral and dorsal matrix zones. This evidence is discussed and compared with literature data describing the results of classical histologic, autoradiographic or immunocytochemical techniques under light and electron microscopy in various species of normal adult Teleosts or in specimens that had undergone reparative or regenerative processes after experimental intervention.

Animals↗
PubMed1992

Nucleotide sequence of the 18S ribosomal ribonucleic acid gene from two teleosts and two sharks and their molecular phylogeny.

The 18S rRNA sequence was determined for two teleostean fish species, Fundulus heteroclitus and Sebastolobus altivelis, and two sharks, Squalus acanthias and Echinorhinus cookei. To study the molecular phylogeny of these taxa, the sequences were compared with 18S rRNA sequences of the Coelacanth Latimeria chalumnae, the frog Xenopus laevis, and humans. Maximum parsimony analysis of the sequences resulted in a single most parsimonious tree that is in agreement with the expected phylogeny. The correct phylogenetic tree was also found when using S. altivelis alone as the teleost representative. In contrast, the most parsimonious tree found by using F. heteroclitus as the teleost representative presented anomalous groupings (the teleost branch being grouped with humans), matching results previously obtained. However, a bootstrap analysis showed that some branches containing anomalous relationships were not significantly supported. An explanation for this peculiarity, the differences between our tree and previously identified ones, and their phylogenetic implications are discussed.

Animals↗
PubMed1990

The cranial cartilages of teleosts and their classification.

The structure and distribution of cartilages has been studied in 45 species from 24 families. The resulting data have been used as a basis for establishing a new classification. A cartilage is regarded as 'cell-rich' if its cells or their lacunae occupy more than half of the tissue volume. Five classes of cell-rich cartilage are recognised (a) hyaline-cell cartilage (common in the lips of bottom-dwelling cyprinids) and its subtypes fibro/hyaline-cell cartilage, elastic/hyaline-cell cartilage and lipo/hyaline-cell cartilage, (b) Schaffer's Zellknorpel, typified by the cartilage in the gill filaments of most teleosts examined, (c) elastic/cell-rich cartilage, such as that which supports the barbels and oral valves of catfish, e.g. Corydoras metae, (d) fibro/cell-rich cartilage, as in the submaxillary meniscus of Sphaerichthys osphromenoides, (e) cell-rich hyaline and (f) matrix-rich hyaline cartilage--both of which are common in the neurocranium and gill arches of most teleosts. The range of cartilages seen, and the predominant cartilage type, is recorded for each species and a list is provided of the tissues that most typify different organs or regions of the head. As a preliminary pointer to developmental relationships between the cartilages, note was taken of gradual transitions between one cartilage and another. It is suggested that hyaline-cell cartilage occupies a key position in teleosts as the most labile of the supporting tissues and is highly characteristic of Cypriniformes. The cartilage that best resembles mammalian hyaline cartilage (matrix-rich hyaline cartilage) has a very conservative distribution in different skeletal elements and the least number of associations with other tissues. It is well represented in Siluriformes.

Animals↗
PubMed1990

Genetic analysis of population structure in marine teleosts around Japan.

Genetic differentiation and genetic variability were estimated from data on electrophoretically detectable isozymic loci in 12 species of marine teleosts belonging to 10 families of six orders, this study permitted conclusions concerning population structures within the species of marine teleosts. As a result the 12 species could be grouped into two classes, one of which showed higher genetic diversity and included the species inhabiting coastal areas; the other showed lower genetic diversity and included the species inhabiting offshore areas and spawning free pelagic eggs. Class I and Class II could be further divided into two groups (I-1 and I-2, and II-1 and II-2) on the basis of the level of average heterozygosity. Based on the above classification and ecological characteristics, the degree of genetic differentiation may be defined mainly by the level of mixing of eggs and by fry migration, and only to a small extent by adult migration between localities. The degree of average heterozygosity should be a measure of effective population size of the breeding units within the species but not of the whole species. Putting together the above facts, six types of population structure have been proposed for marine teleosts as follows: Species in type I-1 have formed some large populations with large breeding units in offshore areas; Type I-2-1, species have formed a large number of breeding populations with relatively large effective sizes of breeding units in the coastal areas or rivers where they were hatched, even though the species may have migrated over a wide pelagic area during their juvenile to adult stages. The species in type I-2-2 would have formed a number of local subpopulations with large to intermediate breeding units in the coastal areas they inhabit. Type I-2-3 species have formed two or more completely isolated local races (or subspecies) with relatively large breeding units, but with a low level of genetic differentiation within each local race. The species in Type II-1 would have formed a single large population consisting of a few breeding units with large effective sizes in offshore areas around Japan. Type II-2 species would have formed one large population consisting of a large number of breeding units with small effective sizes in wide offshore areas around Japan.

Alleles↗