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PubMed1986

Dependence of oxygen consumption on Cl- transport and metabolic substrates in the early distal tubule of the Triturus kidney.

The early distal tubule (eDT) and the proximal tubule (PT) were dissected as tissue samples from the Triturus kidney. The oxygen consumption (QO2) of these tubules was measured and the effects on QO2 by transport inhibitors and metabolic substrates were studied. In eDT, complete Cl- replacement with NO3- or an addition of furosemide (2 X 10(-5) M) reduced Qo2 from 8.4 +/- 1.7 to 4.4 +/- 0.8 or from 8.3 +/- 1.6 to 4.4 +/- 0.6 nl X min-1 X mg-1 (dry weight), respectively. Also Na+ replacement with choline or with an addition to ouabain (1 X 10(-3) M) reduced QO2 from 5.9 +/- 0.8 to 3.4 +/- 0.4 or from 13.2 +/- 1.8 to 4.7 +/- 0.3 nl X min-1 X mg-1 (dry weight), respectively. In PT, complete Cl- replacement with NO3- or the addition of furosemide did not affect QO2 significantly, but Na+ replacement with choline or the addition of ouabain reduced it from 8.1 +/- 1.0 to 5.4 +/- 0.7 or from 10.8 +/- 0.9 to 7.4 +/- 0.8 nl X min-1 X mg-1 (dry weight), respectively. The data indicate that about a half of the QO2 in eDT is linked to active Cl- transport, in PT, Cl- is not transported actively and is not affected by furosemide. Effects on QO2 by various metabolic substrates, including TCA-cycle intermediates and metabolizable amino acids and carboxylic acids were tested. Among them, succinate, L-glutamate, L-aspartate, citrate, and acetate were found to effectively increase the QO2. The substrate-dependencies of QO2 in eDT were very similar to those in PT, in kinds of effective substrates and in the extent of increase. These findings suggest that, in eDT and PT, the uptake mechanisms for substrates and their coupling with aerobic metabolism are very similar.

Amino Acids↗
PubMed1986

Effect of D-glucose on oxygen consumption of renal proximal tubules of the Triturus.

Effect of exogenous D-glucose on oxygen consumption (QO2) was investigated in the proximal tubules of the Triturus kidney. In the proximal tubule, which was perfused and incubated with a solution containing Na+, QO2 was increased dependently of the concentration of added glucose. By removal of Na+ from the perfusate and incubation solutions, QO2 kept the level even by increasing adding glucose. The glucose dependence of Qo2 in the proximal tubule showed the saturable manner of a Michaelis-Menten type and gave a half saturation concentration of 1.3 mM. When phlorizin (1 X 10(-3) M) or ouabain (1 X 10(-3) M) was added to the perfusate and incubation solutions, the glucose dependency of QO2 was abolished, even in the Na+-containing solution. When alpha-methyl-D-glucoside (alpha-MG) was used instead of D-glucose, the QO2 of the proximal tubule showed a dependency on the concentration of alpha-MG. On the other hand, when D-mannitol was used instead of D-glucose, the QO2 was independent on the concentration of D-mannitol. The increase in QO2 of the proximal tubule by exogenous D-glucose could be explained by the stimulation of the Na+ pump, which is the consequence of enhanced Na+ entry through Na+/D-glucose cotransport across the luminal membrane.

Animals↗
PubMed1986

Sodium-independent, hydrogen ion-dependent changes in membrane potential and conductance induced by dipeptides in Triturus enterocytes.

The effects of Na+ and pH in the medium on dipeptide transport across Triturus small intestinal brush border membrane were studied electrophysiologically. Although glycylglycine exists mainly in the zwitterionic form at pH 7.30, it induced marked depolarization in the membrane potential and reduction in the input resistance both in the presence and absence of Na+ in the medium. Similar Na+-independent depolarization and resistance change were also observed with L-carnosine. On the contrary, glycine induced membrane depolarization and reduction in the input resistance only in the presence of Na+ in the medium. When pH of the medium was lowered to 6.00, the magnitude of the depolarization induced by glycylglycine increased by 33%, while at pH 8.30, it decreased by 39%. These data indicate that dipeptide transport across the intestinal brush border membrane is coupled with H+ and has no direct interaction with Na+.

Animals↗
PubMed1988

Forebrain development in control and hypothyroid larvae of Triturus cristatus carnifex.

Some cytological and developmental aspects of the forebrain gray matter were studied in the control and the hypothyroid larvae of Triturus cristatus carnifex. The mitotic cell percentages in the periventricular germinal layer, the fusiform shape of the recently divided neuronal cells and the transitory gray matter cleavage, are characteristic of the immature status of the central nervous system (CNS) in this species. The hypothyroidism obtained during two months of thiourea treatment slows down the development in all the forebrain areas of the experimental larvae. Nevertheless, the nucleus olfactorius anterior and the corpus striatum, which have a longer mitotic activity with respect to the other neuronal structures, are more deeply affected by thyroid atrophy. Thyroid activity and forebrain maturation are discussed on the basis of the literature and our data with regard to their influence on behavior and evolution.

Aging↗
PubMed1999

PCNA positivity in the telencephalic matrix areas in the adult of a newt, Triturus carnifex.

The Proliferating Cell Nuclear Antigen (PCNA) is an auxiliary protein of the DNA polymerase delta, belonging to the cyclin family, which attains appreciable levels only in those phases of the cell cycle in which DNA synthesis occurs. Using an immunocytochemical method that exploits this proliferative marker, we observed a certain PCNA positivity in the telencephalon of normal adult individuals of Triturus carnifex. The elements that display this peculiarity occupy an ependymal and/or sub-ependymal site. They are located in the anterior portion of the telencephalon only at the dorsal level and tend to decrease in number until they disappear temporarily as the intermediate portion is approached. In the posterior portion of the telencephalon, the dorsal labelling patterns, the size of which is however smaller than that observed more anteriorly, reappear and in the ventral region a large population of labelled cells appears. Then, again proceeding in a caudal direction, while the PCNA-positive elements lying dorsally diminish and disappear, they persist in the ventral region and gradually taper off until they final disappear where the telencephalic ventricles come together. This immunocytochemical picture supports the findings of other authors in adult Urodeles under both normal and experimental conditions (with classical and autoradiographic histological techniques) concerning the persistence of the telencephalon in dorsal and ventral germinative areas responsible for physiological and plastic neurogenetic events.

Animals↗
PubMed2000

Relationships between hepatic melanogenesis and respiratory conditions in the newt, Triturus carnifex.

The Kupffer cells (melanomacrophages) in the livers of lower vertebrates contain varying quantities of melanin according to the season. Specimens of Triturus carnifex raised for 2 months at 6 degrees C and then transferred to water at 22 degrees C show a rapid increase in the hepatic accumulation of the pigment. The Kupffer cells make up more than one fourth of the liver mass in chlorbutol-anesthetized animals isolated for 6-7 hr in hypoxic water at 18 degrees C (to bring the oxygen content in a 620-mL respiratory chamber from 1.1 ppm to 0.0). Thus, hepatic melanin is synthesized when the newt's oxygen supply is inadequate to meet its metabolic needs; melanogenesis, however, requires the presence of oxygen and does not occur in anesthetized specimens immersed in a totally anoxic fluid such as paraffin oil. The intraperitoneal injection prior to hypoxic treatment of 1 mg/g of body weight of kojic acid (inhibitor of the enzyme tyrosinase which catalyzes melanin synthesis) blocks melanogenesis and doubles oxygen consumption. The combination of hypoxia and tyrosinase inhibition causes permanent damage to essential functions of the nervous system, while hypoxic treatment alone has no irreversible consequences. The genic expression of tyrosinase in hypoxia appears to be a physiological response aimed at prolonging survival time in anaerobiosis by lowering the metabolic level; melanin would be an inert subproduct of this function.

Animals↗
PubMed2000

Myotomal myogenesis in Triturus vulgaris L. (Urodela) with special reference to the role of mesenchymal cells.

Two stages can be distinguished in the differentiation of myotomal muscle fibres in Triturus vulgaris. In the first stage only synchronously differentiating myotomal cells are engaged; in the second stage mesenchymal cells also take part in the process. Myotomal cells (primary myoblasts) fuse to form 2-3 nucleate myotubes. Only in the caudal part of the embryo mononucleate myotubes persist. The mononucleate myotubes, like polynucleate ones, occupy the whole length of the myotome. The differentiation of myotubes is accompanied by vitellolysis. At further development stages mesenchymal cells enter the intermyotomal fissure, after which they migrate to the myotomes, between the myotubes. The cells that remain in the intermyotomal fissures retain their fibroblastic potential (they synthesise collagen). Their daughter cells adjoining the myotubes acquire myogenic abilities. Their myoblastic potential is evidenced by their ability to fuse with the myotube. Fusion of secondary myoblasts (of mesenchymal origin) with the myotube results in further growth of the myotubes. In T. vulgaris myotomal myotubes and muscle fibres developing from them are of myotomal-mesenchymal origin.

Animals↗
PubMed2001

Genetic differentiation of the two subspecies of the smooth newt inhabiting Romania, Triturus vulgaris vulgaris and T.v. ampelensis (Urodela, Salamandridae) as revealed by enzyme electrophoresis.

Starch gel electrophoresis was applied to quantify genetic variation and divergence in samples from Romanian populations of the nominal form of the smooth newt Triturus vulgaris and those of the endemic Romanian subspecies T.v. ampelensis, a population from a parapatric area was additionally included. All the samples had similar levels of genetic variation measured by the mean heterozygosity, proportion of polymorphic loci, and mean number of alleles per locus. T.v. ampelensis samples were genetically clearly different from the nominal form samples, the mean genetic distance between the two subspecies was being estimated as DN = 0.114. No fixed differences in allele composition between the two subspecies were found, although some of the alleles were found either exclusively in the nominal form (Aat-1) or in T.v. ampelensis (Mpi a). Other alleles at these loci together with Mdh-1 differed markedly in frequency. The population from the parapatric area was intermediate in allelic composition, but grouped together with the T.v. ampelensis samples in a maximum likelihood tree (99.7% bootstrap support for this grouping). The data indicate that the two subspecies interbreed in a parapatric zone. The molecular clock applied to electrophoretic data indicates that these two forms split during the Pleistocene.

Animals↗
PubMedDate not supplied

Analysis of morphogenetic potential of caudal spinal cord in Triturus carnifex adults (Urodele amphibians) subjected to repeated tail amputations.

The present research was aimed at testing whether the extraordinary morphogenetic and histogenetic potential exhibited in the regenerating new tail remains constant even after repeated amputation or whether it changes as a result of the mechanisms responsible for the regenerative process. Particular attention was focused on regeneration of the spinal cord and ganglia. For this purpose, tail regeneration in adult specimens of Triturus carnifex subjected to repeated amputation (up to 7 times) was compared with that of control animals subjected to a single amputation. Results show that although it slowed down the morphogenetic and differentiative phase, repeated amputation did not significantly alter either the morphogenetic or the histogenetic potential of the ependymal layer of the regenerating spinal cord. The latter result leads to hypothesized that the cells of the ependymal layer of the stump, which are responsible for the formation of the apical ampulla and the ependymal tubule inside the regenerative blastema, do not derive from undifferentiated reserve elements triggered after tail amputation but rather from differentiated ependymal elements that dedifferentiate after the trauma and re-acquire embryonic potential. If this regeneration were actually to take place at the expense of the reserve elements, the continual regenerative processes induced by the repeated amputation would lead to the increasing depletion of these elements and a consequent reduction in regenerative capacity.

Amputation, Surgical↗
PubMed1975

[Morphology and histochemistry of regenerating corneal epithelium in Triturus cristatus. 1. Preliminary observations].

The corneal epithelium of Triturus cristatus was studied by light and electron microscopy. It consists of three cellular layers; the superficial cells, which show numerous short microvilli, are held together by typical junctional complexes. The basal cells adhere to the basal lamina by hemidesmosomes. Furthermore all cells form with the neighboring ones interdigitations and establish with them desmosomal contacts. Secretion granules and vesicles are present throughout the epithelium, mainly in the upper layer; they are filled with an electron dense material, containing glycoproteins as suggested by the histochemical analysis. Mitoses are very frequent in the basal layer. Occasionally exfoliating cells showing signs of degeneration were observed in the superficial layer. The morphological changes occurring during epithelization of wound linearly incised, were studied by light microscopy at several time intervals and the detachement and migration of the cells was particularly investigated. Very early after wounding (5') necrotic cells and cell debris are present at the wound edges. Soon after, thin protrusions originate from surrounding undamaged cells and push through the cellular fragments sliding on the underlining connective tissue. After 2 h, the wound is completely closed by such flattened protrusions. The newly formed epithelium becomes gradually thicker (3-7 h) and the mitotic activity till now suppressed, is resumed (24 h). Studies are in progress on the modifications of the junctional complexes and on the enzymatic mechanism possibly involved in cell mobilization.

Animals↗
PubMed1992

Degenerative and regenerative phenomena in brain heterotopic homoplastic transplants of adult Triturus carnifex (Urodele Amphibians).

The brains of adult Urodele Amphibians (Triturus carnifex Laur.) were homoplastically transplanted in conditions of complete morpho-functional isolation. Despite the heterogeneous nature of the histological aspects observed, the results point to the following general pattern for the fate of the brain transplants: 1) rooting phase (about day 5 after the operation) as indicated by degenerative patterns affecting the various encephalic districts and mainly involving the more peripheral neurons and the nerve fibers, and to a lesser extent the periventricular gray and the ependyma; 2) phase of rejection by host (from day 10 until end of experiment on day 30) as indicated by lymphocytic infiltration, the presence of macrophages and pyknoses, and the formation of a connective tissue capsule surrounding the transplant; 3) regenerative phase (from about day 10) as indicated by the onset of mitotic activity affecting elements of the ependymal epithelium and the periventricular gray, particularly in the telencephalic district. By the end of the experiment, in most of the transplants examined, degenerative processes were found to have prevailed over the regenerative phenomena. However, in some cases, and particularly in one of them, a distinctly higher degree of structural organization of neurons and nerve fibers can be observed at the telencephalic level. It may be postulated that, whenever a greater degree of compatibility exists between the host and the transplanted organ, it is possible, even in conditions of complete morpho-functional isolation, for the brain to express regenerative power through the ependyma and the matrix zones which have already been identified by some Authors in telencephalic periventricular areas or scattered through the mesencephalic gray matter.

Animals↗
PubMed2005

Molecular and ultrastructural studies of the sperm chromatin from Triturus cristatus.

The study of nuclear molecular architecture during gametogenesis represents one approach towards the deciphering of the molecular organization of eukaryotic chromatin. During spermatogenesis, chromatin undergoes several dynamic transitions, which are often associated with important changes not only in its physical conformation but even in its composition and structure. Dynamic alterations in chromatin structure mediated by postsynthetic histone modification and DNA methylation constitute a major regulatory mechanism of gene function of eukaryotes. Using transmission electron microscopy and molecular investigations, some peculiar aspects of chromatin organization and evolution in spermatogenesis of the crested newt Triturus cristatus were investigated. We focused our investigations on the dynamics of chromatin structure after treatment with TSA (a histone deacetylase inhibitor).

Acetylation↗
PubMed1990

The endocrine pancreas of Triturus cristatus: an immunocytochemical study.

The endocrine pancreas of Triturus cristatus carnifex was studied with the aid of immunocytochemical methods, showing cells immunoreactive to anti-insulin serum (B cells), a small population of cells immunoreactive to anti-glucagon serum only (A cells), rare cells positive to anti-PP serum only (PP or F cells), and a larger population of cells immunoreactive both to anti-glucagon and to anti-PP sera. B cells lied in the core of the islet, while the A/PP cells were located at the periphery, forming digitations extending into the exocrine parenchyma. D cells were present in small number in the islet while they were more numerous scattered in the exocrine parenchyma. A/PP cells as well as D cells showed one or two long cytoplasmic extensions often in contact with blood vessels.

Animals↗
PubMed1989

Annual changes in the number, testosterone content and ultrastructure of glandular tissue cells of the testis in the marbled newt Triturus marmoratus.

The testes of 8 specimens of Triturus marmoratus were collected during each month of 1987 and processed for electron microscopy and light microscopy demonstration of testosterone (T) following the ABC (avidin-biotin peroxidase complex) method. According to their staining affinity for anti-T antibodies, the glandular tissue cells were classified as T-, T+, T++, and T and the annual changes in the numbers of these cell populations, as well as in the volume occupied by the glandular tissue, were calculated. The volume occupied by the glandular tissue increases from September to December; it begins to decrease in April and disappears from June to August. The glandular tissue is formed from the interstitial cells that surround the lobules containing differentiating germ cells. During the spermatogenic process, the interstitial cells do not show staining affinity for anti-T antibodies. In August-September, the interstitial cells around the lobules that have completed spermatogenesis become positively stained (T+) and form the glandular tissue when the spermatozoa leave the testis. The numbers of intensely stained cells in the glandular tissue (T++ and T ) increase from September to November; begin to decrease in December; disappear in January-February; increase again in March and decrease again in April until they disappear in June-September. The interstitial cells, before their transformation in glandular tissue, are ultrastructurally similar to fibroblasts. After their transformation these cells increase in size and develop abundant smooth endoplasmic reticulum, mitochondria with tubular cristae and lipid droplets. This morphological pattern is maintained in the glandular tissue from September to April in spite of the changes in staining affinity during this period.

Animals↗
PubMed1988

Influence of vitamin A palmitate on the growth of regenerating Triturus alpestris forelimbs.

The objective of this investigation was to analyse the effects of vitamin A palmitate orally administered to young postmetamorphic Triturus alpestris on the growth of regenerates. Vitamin A was administered for 4, 7, 11 and 14 days after amputation at the middle of the right zeugopod. Growth of regenerates was evaluated on the basis of external size measurements and blastema cell proliferation. Calculation of the percentages of cells in each cell-cycle phase and estimation of mitotic indices during the period of drug administration were performed by microdensitometric scanning of Feulgen-stained nuclei and counting of chromosome configurations, respectively. Vitamin A was found to induce polyploidism, to enhance transition from G1- to S-phase cell nuceli, to prolong the duration of G2-phase to the detriment of S-phase and to promote mitotic activity in the mesenchyme cells. In accordance with the above, an acceleration in the growth rates of treated blastemas with respect to controls was observed.

Animals↗
PubMed1988

Vitamin A induced bilateral asymmetries in triturus forelimb regenerates.

After amputation of both forelimb of young, postmetamorphic Triturus alpestris through the middle of the zeugopod, the left and right regenerates grew asynchronously. As a result of oral administration of vitamin A palmitate (250 IU/gbw/day), from the 4th to the 13th dpa, the growth rate of the right regenerates was relatively higher than that of the left ones. Moreover, the percentage of skeletal abnormalities as well as proximodistal duplications (proximalizations), induced by vitamin A, was nearly twice as high in the right regenerates as compared to their left counterparts.

Aging↗
PubMedDate not supplied

Morphogenesis of the adrenal gland of Triturus cristatus carnifex during larval development and metamorphosis.

During the morphogenesis of the adrenal gland of Triturus cristatus, a cranio-caudal differentiation is observed together with a migration of the two cell types composing the adrenal gland: the steroidogenic cells and the chromaffin cells. During the cranio-caudal differentiation the two cell type gradually occupy an increasingly posterior position on the mesonephros until they are distributed, in the adult, along the whole kidney. The migration brings the cells from dorsal or dorso-lateral position, with respect to the venous vessels, to the ventral surface of the kidney, an arrangement typical of the adult.

Adrenal Glands↗
PubMed1979

[Thyroid incorporation of radioactive iodine in neotenic tritons (Triturus helveticus Raz.). In vivo studies by high resolution radioautography. Comparison of iodine incorporation in adults and larvae].

In vivo kinetics of radioiodine incorporation have been established for 70 newts, collected from Triturus helveticus Raz. populations where spontaneous neoteny occurs. Fifty of these newts which appeared to present four degrees of neoteny (more or less metamorphosed), have been studied. Main results obtained were: 1) The intensity of the iodine incorporation varies according to the degree of neoteny. The higher is this one, the lower is the intensity. 2) In general, iodine uptake rates are more or less similar to these of adults, but more often the evolution of the 125I uptake approaches a plateau-curve. From thyroid radioautographies on some animals (17 neotenic and 2 adult newts) for which in vivo iodine kinetics have been examined and on 9 normal larvae in premetamorphosis or in metamorphosis, we have noticed in those neotenic thyroids, a very small number of silver grains on apical vesicles and colloidal lumina when the degree of neoteny is the highest. This number of marked apical vesicles and colloid is more important in the neotenics which have lost some larval characters. Silver grains on colloid droplets indicating thyroid hormone excretion are inexistent in the most larval neotenics, more numerous in most metamorphosed neotenics. But they always are less numerous than in metamorphosing larvae. For a few animals, the fixation curve is very high, probably because of a stimulation of thyroid function, induced by the test and not because of a goitrous tendancy, as radioautographic observation of their thyroid shows. Thyroid function and its relation with the origin of this total and accidental neoteny are discussed.

Aging↗