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At least 865 records · Page 48Linked to original sources
PubMed1981

Computer-assisted analysis of chromosomes of the European crested newt.

A computer programme has been developed for partly automating the process of chromosome analysis of the European crested newt (Triturus cristatus carnifex). Chromosome classifications made by the computer and by the cytologist have been compared for a sample of 130 spermatogonial metaphase. The twelve pairs of chromosomes have been classified into three groups. The overall error rate achieved by the computer was 14% for chromosome assignment to single pairs, and 3.8% for chromosome assignment to the proper group.

Animals↗
PubMed1978

Mesodermalization of amphibian gastrula ectoderm in transfilter experiments.

Transfilter experiments were carried out with competent gastrula ectoderm of Triturus vulgaris and Ambystoma mexicanum as the reacting materials and blastoporal lip, alcohol-treated bone marrow and archenteron roof as the inducing materials, It was shown that a mesodermal inducing substance is able to penetrate Nuclepore filters of different pore sizes (3.0, 1.0, 0.4, 0.2 micrometer). The degree of mesodermal differentiations depends on the reacting materials, the inductors and the filters which were used in the transfilter experiments.

Ambystoma↗
PubMed1978

Neural induction, a two-way process.

A quantitative analysis of Triturus alpestris recombinates of newly invaginated "caudal" archenteron roof with either competent gastrula ectoderm or non-competent neurula ectoderm has demonstrated that neuralisation evoked by the underlying archenteron roof affects, in its turn, the regional differentiation of the latter. It does so by enhancing its notochordal differentiation; so, neural induction is clearly a two-way process. Somite differentiation is not significantly different in the two series. This is especially remarkable since both series show positive correlations between the amounts of notochordal and somite structures. The explantation is that the correlation coefficients differ considerably in the two series. The possible reason for this is discussed. Moreover the recombinates with competent gastrula ectoderm demonstrate that the size of the neural structures is determined by the total mass of the axial mesoderm and not by that of the notochord or that of the somites separately.

Animals↗
PubMedDate not supplied

Small angle dislocations of the newt limb axes can test the validity of several regeneration models.

We describe two experiments on the regenerating forelimbs of the urodele Triturus cristatus. In the first, a contralateral grafting is performed where the anteroposterior axis of the regenerating blastema coincides with the dorsoventral axis of the host stump. In the second, the regenerating blastema is ipsilaterally rotated on the stump at angles 90 degrees or 270 degrees. For these experimental setups several regeneration models, each based on different reference frames (cartesian versus polar coordinates), have diverging predictions for the resulting supernumerary outgrowths. We have analyzed these outgrowths morphologically and histologically and we conclude that both experiments are well described by a hierarchical extension of the Polar Coordinate Model.

Amputation, Surgical↗
PubMed1995

[Mirror symmetrical and "left dominant" organization in the gastrula stage molted parabiotic larva of mountain salamander].

Gastrulae of Triturus alpestris were laterally fused (body axes in equal directions). The parabiotic larvae mostly showed an undivided body with tail, but exhibited two heads. Defects of organogenesis were frequently observed in the gut, and, to some fewer extent, in the heart. The gut mostly develops undivided, the heart in singular or (with transitions) as two organs. The number of organ-inversions and partial inversions was high (table 1). In addition a transindividual organ-symmetry (mirror-image symmetry of the "pair situs") was abundant (table 3, fig. 6) and the gut and the habenular nuclei showed a strong dominance for that phenotype. The organ inversions were more abundant in the right organ or part of the organ. These right-left-differences were statistically significant referring to the inversion tendency of the heart and the habenular nuclei (table 2). This "left-dominance" observed in the organ Anlagen investigated is discussed in regard to results published previously.

Animals↗
PubMed1993

Co-occurrence of substance P and enkephalin-like immunoreactivities in the prosencephalon of two amphibians.

We studied the co-occurrence of substance P-(SP) and leucine (or methionine) enkephalin (ENK)-like immunoreactivities in the prosencephalon of two amphibians: Rana esculenta L. (Anura) and Triturus carnifex Laur. (Urodela) using single and double immunohistochemical methods. The two peptides (SP-ENK) were sometimes found colocalized in neuronal cell bodies and processes. Double-labelled neurons were seen in the nucleus accumbens, lateral septal nucleus, preoptic area, dorsal and ventral hypothalamic nuclei of the frog, whereas in the newt co-occurrence was shown in neurons of the primordium pyriform, corpus striatum, pars ventralis thalami, preoptic area and nucleus infundibularis dorsalis and ventralis. Furthermore, in both amphibians, fibres simultaneously showing SP- and ENK-positivity were observed in the amygdaloid complex, preoptic area and in the posterior hypothalamus, around the infundibulum. Co-occurrence studies in comparative neuroanatomy are relevant, as shown in the present paper regarding the similarities of SP-ENK distribution in the striatopallidal and striatonigral systems of tetrapods.

Animals↗
PubMed1993

Lectin histochemistry of cell-surface glycoconjugates in the primary olfactory projections of the newt.

The binding of 14 lectins were performed on paraffin-embedded sections of the olfactory bulb of Triturus to identify specific glycoconjugates on the cell surface of primary olfactory projections. The histochemical lectin staining patterns indicate that the membrane of olfactory neurons terminating in the main olfactory bulb contained prevalently oligosaccharides with alpha-acetyl-D-galactosamine as terminal residues. In the accessory olfactory bulb, instead, the primary olfactory projections possess a high density of alpha-D-galactose as sugar residues. The selective lectin binding on the surface of primary olfactory axons suggests that specific cell surface glycoproteins may have a role in the axonal growth due to the continual cycle of proliferation and death of olfactory receptors.

Animals↗
PubMed1995

Medullary and gangliar regeneration after unilateral removal of a segment of spinal cord of the trunk and corresponding ganglion in adult newts.

Regeneration of the spinal cord, segmental nerves and sensory ganglia takes place after tail amputation in the newt. Many histological and immunocytochemical observations provide evidence that the ependymal tube is the source not only of new neurons and glial cells in the spinal cord, but also of some cells that go on to participate in the formation of the spinal ganglia of the regenerating tail. In previous experiments involving the removal of the spinal ganglia of the trunk, no regeneration was observed and it is thought that the trunk region differs from the tail region with regard to the ability to regenerate sensory ganglia. However, in these experiments the spinal cord of the trunk was not damaged. In the present work involving adult newts (Triturus carnifex Laur.), unilateral ablation of a segment of the spinal cord of the trunk in addition to removal of a corresponding spinal ganglion was performed. In these experimental conditions, regeneration of a rudimentary spinal ganglion near the regenerated side of the spinal cord segment was observed in several cases. Histological observations carried out 2, 4, 6 and 13 months after the operation support the view that some cells migrating from the lateroventral part of the regenerating side of the spinal cord via the developing ventral root could participate in the formation of the rudimentary spinal ganglion.

Amputation, Surgical↗
PubMed1998

B24 protein stored in lampbrush spheres is involved in early cleavage in urodele amphibians.

A cDNA encoding a protein (B24) belonging to the Mcm/P1 family was isolated from the newt Triturus carnifex. In eukaryotes, the members of the Mcm/P1 family are essential factors in the DNA replication process. B24 protein (TcMcm3) is present in salamandrid ovarian oocytes and early embryos; its role was tested by injecting specific anti-B24 monoclonal antibodies into the cytoplasm of one blastomere of two-cell stage embryos. The injected blastomere encountered cleavage arrest either soon after the injection or following one or two divisions; later, it degenerated. Instead, the uninjected blastomere went on developing and organizing a hemi-embryo, which does not grow beyond the tailbud stage. These results are consistent with the hypothesis that the B24 protein is involved in DNA replication at cleavage. The B24 protein studied here appears to play a specific role in early development; other variants of the Mcm3 group seem to be employed by different adult tissues.

Amino Acid Sequence↗
PubMed1976

Incorporation of tritiated cytochalasin B into ectodermal explants of the amphibian gastrula.

Ectodermal explants from gastrulae of Triturus alpestris were exposed to tritiated cytochalasin B (5 and 10 mug/ml) for 1/2-2 1/2 h. The flat explants failed to heal into compact spheres and the component cells gradually rounded up. Radioactivity in the fixed and sectioned material was analysed by light and electron microscopic autoradiography. Silver grains were found predominantly over the yolk platelets, but were also scattered over other cellular components. Areas containing pigment granules or the feltwork material, present in the apices of dissociating cells of the superficial layer, exhibited higher activity than areas containing mitochondria or cytoplasmic matrix. Lipid droplets and nuclei showed comparatively little activity. The results are discussed in relation to previous findings on the uptake of tritiated cytochalasin D by cell fractions.

Animals↗
PubMed1999

Morphological variation of hypaxial musculature in salamanders (Lissamphibia: caudata).

Despite the acknowledged importance of the locomotory and respiratory functions associated with hypaxial musculature in salamanders, variation in gross morphology of this musculature has not been documented or evaluated within a phylogenetic or ecological context. In this study, we characterize and quantify the morphological variation of lateral hypaxial muscles using phylogenetically and ecologically diverse salamander species from eight families: Ambystomatidae (Ambystoma tigrinum), Amphiumidae (Amphiuma tridactylum), Cryptobranchidae (Cryptobranchus alleganiensis), Dicamptodontidae (Dicamptodon sp.), Plethodontidae (Gyrinophilus porphyriticus), Proteidae (Necturus maculosus), Salamandridae (Pachytriton sp.), and Sirenidae (Siren lacertina). For the lateral hypaxial musculature, we document 1) the presence or absence of muscle layers, 2) the muscle fiber angles of layers at mid-trunk, and 3) the relative dorsoventral positions and cross-sectional areas of muscle layers. Combinations of two, three, or four layers are observed. However, all species retain at least two layers with opposing fiber angles. The number of layers and the presence or absence of layers vary within species (Necturus maculosus and Siren lacertina), within genera (e.g., Triturus), and within families. No phylogenetic pattern in the number of layers can be detected with a family-level phylogeny. Fiber angle variation of hypaxial muscles is considerable: fiber angles of the M. obliquus externus range from 20-80 degrees; M. obliquus internus, 14-34 degrees; M. transversus abdominis, 58-80 degrees (acute angles measured relative to the horizontal septum). Hypaxial musculature comprises 17-37% of total trunk cross-sectional area. Aquatic salamanders show relatively larger total cross-sectional hypaxial area than salamanders that are primarily terrestrial.

Anatomy, Cross-Sectional↗
PubMed1980

Fine structure of the surfaces of the epithelium and mesenchyme of the newt limb regenerate, separated in salt solution: 14 to 25 days.

Forelimbs of the newt Notophthalmus (Triturus) viridescens were amputated at the wrist, and at 14 to 25 days, the new limb regenerates were removed by a razor-blade cut. After incubation of the isolated regenerates in a medium containing only inorganic salts, the epithelium was removed easily from the underlying mesenchyme. The surfaces separated in the salt solution were examined using scanning and transmission electron microscopy to evaluate the completeness of the separation and the extent of tissue damage near the plane of separation. Rarely was an epithelial cell found clinging to the mesenchymal surface, supporting previous light microscopic observations. The most apparent morphological damage was sustained by the basal epithelial cell surfaces, which exhibited blebbing; the formation of vacant vesicles within the cytoplasm near the newly exposed plasma membranes; the structural disruption of some organelles; and the tearing away of fragments of the basal epithelial cell plasma membranes, which remained adherent to the mesenchymal surface during separation procedure. Examination of the structure of the epithelial-mesenchymal interface of intact regenerates showed that the plane of epithelial-mesenchymal separation was, for the most part, between the basal epithelial cell membrane and its substrate, an extracellular material which remained at the mesenchymal surface after separation. This substrate was in the form of an extracellular material closely adherent to the basal epithelial cell membrane at the distal tips of the regenerates; a developing basal lamina at the periphery of regenerates undergoing blastema accumulation; or a mature basal lamina at the base of digit stage regenerates. The usefulness of these separated tissues for future experimentation and the evaluation of the nature of the epithelial substratum throughout the course of limb regeneration are discussed.

Animals↗
PubMed1988

Distribution and characterization of neuropeptide Y-like immunoreactivity in the brain of the crested newt.

The newt brain represents a simplified model for the increasingly complex vertebrate neuronal organization. The localization of neuropeptide Y-like (NPY-like) containing neurons in the brain of Triturus cristatus was studied by means of indirect immunofluorescence, peroxidase-antiperoxidase, and avidin-biotin techniques using a highly specific antiserum. NPY-like positive cell bodies were observed in several areas, most notably in the telencephalon (primordium hippocampi and amygdaloid complex), the preoptic and suprachiasmatic areas, the hypothalamus, the dorsal thalamus, the tegmentum, and the rhombencephalon (laterolateral grey column and raphe area). Nerve fibres were particularly abundant in the pallium, striatum, septum, amygdaloid, preoptic neuropils, and pars intercalaris diencephali. Bundles of NPY-immunoreactive fibres also were visualized in the dorsal thalamus and in the posterior hypothalamus. The pars intermedia lacked any NPY-like positive fibres. Neuronal processes also were found in the tectum mesencephali and in the body of the cerebellum. A prominent NPY-like fibre network was observed in the octavolateralis. Concentrations of NPY measured by means of a specific radioimmunoassay were threefold higher in the hypothalamus (15.2 +/- 1.3 ng/mg proteins) than in the rhombencephalon (4.9 +/- 0.3) and the mesencephalon (4.3 +/- 0.2). The concentration found in the telencephalon was 2.1 +/- 0.3 ng/mg proteins. Sephadex G-50 gel chromatography of whole brain extracts indicated the presence of high molecular weight forms of NPY-like material in addition to the authentic peptide. Both amphibian and mammalian NPY peptides had an apparent molecular weight of 4,000 daltons, as evidenced by immunoblotting analysis. High-performance liquid chromatography demonstrated, however, that the newt peptide was slightly less hydrophobic than porcine NPY. The present findings indicate that NPY-immunoreactive neurons are widely distributed in the brain of urodeles. Our data indicate that the NPY molecule has been relatively well preserved during evolution.

Animals↗
PubMed1977

Effects of neurotransmitters upon the discharge of secretory product from the cutaneous glands of the red-spotted newt.

The effects of sympathetic and parasympathetic agonists and antagonists on discharge of secretory product by the granular and mucous glands were examined in the red-spotted newt, Notopthalmus viridescens viridescens. Observations were made also on the South African clawed toad. Xenopus laevis, the grass frog, Rana pipiens, and the crested newt, Triturus cristatus. In contrast to the granular glands of the South African clawed toad and the grass frog, which were stimulated by alpha-adrenergic agents, those of the red-spotted newt discharge in response to acetylcholine, either in vitro when added to the Holtfreter's solution in which explants were incubated, or in vivo when injected subcutaneously. Granular glands of the crested newt were also dischared in response to subcutaneous injection of acetylcholine. Stimulation of the granular glands by acetylcholine was blocked by atopine but not by tubocurarie, indicating that the cholinergic receptors are muscarinic rather than nicotinic. The mucous glands of the red-spotted newt, on the other hand, did not discharge in response to either acetylcholine or to adrenergic agents.

Acetylcholine↗
PubMed1979

Separation of the epithelial and mesenchymal components of the newt limb regenerate with salt.

After incubation of isolated forelimb regenerates of Notophthalmus (Triturus) viridescens at all developmental stages for 60 minutes at 37 degrees C in a salt medium containing 111 mM sodium chloride, 5.6 mM potassium chloride and 100 mM sodium phosphate buffer at pH 7.5, the wound epithelium of each regenerate was removed intact from its underlying mesenchymal component. The suggestion is made that the salt medium is an effective epithelial-mesenchymal separating agent due to a combination of its hypertonicity, high ionic strength and the fact that the medium precipitates calcium as calcium phosphate. Attempts to dissect away the epithelium from the mesenchyme after incubation of isolated regenerates in sodium phosphate containing 1% or 3% Difco 1:250 trypsin, 10 mM EDTA or 150 units collagenase/ml medium were unsuccessful. Epidermis of adult newt forelimb skin was removed only after extended incubation of the forelimbs in the salt medium for three hours at 37 degrees C or after freezing isolated forelimbs in buffer and subsequent thawing.

Animals↗
PubMed1983

J10 lactate-induced polycythemia in newts.

Specimens of Triturus cristatus carnifex (Laurenti) raised for about 3 weeks in a 3 gm/liter solution of sodium lactate present a slight alkalosis and a mean increase of about 35% in the red blood cell count in comparison to control animals raised in identically oxygenated water; analogous treatment with an equal molar concentration of sodium pyruvate produces only alkalosis. Since lactate alone determines an increase in the number of erythrocytes as does hypoxia, and hypoxia always induces an increase in plasma lactate levels, it can be deduced that erythropoietin (ESF) production is stimulated by an increase in plasma lactate and not directly by a lack of oxygen. The hypothesis that ESF in newts is produced by the "lactate-sensitive cells" of the renal corpuscles, which hypertrophy after experimental anaemia or treatment with lactic acid salts, is indirectly confirmed.

Alkalosis↗
PubMed2002

Immunohistochemical detection of the retinoid acid receptors (RXR-alpha, -beta, -gamma) and Farnesoid X-activated receptor (FXR) in the marbled newt along the annual cycle.

Retinoid acid receptors (RXR-alpha, -beta, -gamma) and Farnesoid X-activated receptor (FXR) expression in the testis of the marbled newt were investigated with special attention to the changes during the annual testicular cycle, using light microscopy immunohistochemistry and Western blot analysis. The annual testicular cycle of the marbled newt (Triturus marmoratus marmoratus) comprises three periods: (a) proliferative period (germ cell proliferation from primordial germ cells to round spermatids, April-June); (b) spermiogenesis period (July-September); and (c) quiescence period (interstitial and follicular cells form the glandular tissue, October-April). In the proliferative period, primordial germ cells and primary spermatogonia immunostained intensely to the three types of RXRs and also to FXR. In the other periods, immunostaining to these antibodies was weak or absent. Secondary spermatogonia stained weakly to the four antibodies in the proliferative period, and only to FXR, also weakly, in the spermiogenesis period. Immunoreactive primary spermatocytes were weakly labeled with the RXR antibodies in the proliferative period. Spermatids and spermatozoa did not stain to any antibody in any period. Follicular cells only immunostained to RXR-gamma and only in the quiescence period when they are forming the glandular tissue, together with the interstitial cells. As follicular cells, interstitial cells only immunostained in the quiescence period; however, they immunoreacted to the three types of RXRs. These findings suggest that in the newt, RXRs and FXR are involved in spermatogenesis control by regulating the proliferation of primordial germ cells and spermatogonia. In addition, RXR-gamma seems to be also involved in the development of the glandular (steroidogenic) tissue.

Animals↗