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Nascent (newly synthesized) DNA obtained from the regenerating len-system of Triturus is first isolated as single stranded molecules. These imtermediates are later converted into double-stranded molecules.
Amphibians (tadpoles of the frog Bombina bombina [L.] and the newt Triturus vulgaris [L.]) and aquatic insects (larvae of the alderfly Sialis lutaria [L.] [Megaloptera], dragonflies Sympetrum sanguineum [Miller] and Coenagrion puella [L.] [Odonata], and the caddisfly Oligotrichia striati [L.] [Trichoptera]) were found to serve as paratenic hosts for the third-stage larvae (L3) of the nematode Anguillicola crassus Kuwahara, Niimi et Itagaki, 1974, a pathogenic swimbladder parasite of the eel Anguilla anguilla (L.) in Europe and elsewhere. This is the first evidence that, in addition to prey fishes and some aquatic snails, amphibians and aquatic insects can serve as paratenic hosts for this nematode parasite. A. crassus third-stage larvae were found, largely unencapsulated (encapsulated only in S. lutaria), mostly in the body cavity, on the gut surface and, less often, in the liver and in the subcutaneous tissue of legs in amphibians, and in the body cavity and on the gut surface in insect larvae; they could survive for at least 49 d in T. vulgaris and 69 d in S. lutaria. The capability of these larvae from S. lutaria (69 d post-infection) to infect the definitive host (eel) was confirmed by experimental infection of an eel.
Swimbladder of the crucian carp, Carassius auratus, was found to be better as a vegatalizing tissue than other tissues, such as guinea-pig bone marrow, when presumptive ectoderm of Triturus gastrulae was used as reacting tissue. Swimbladder usually induced assemblies of highly organized mesodermal tissues, such as notochord, somites and pronephric tubules, some of which were covered by mesodermal epithelium without any epidermal covering. A special character of the effect of swimbladder was the rather frequent induction of solid balls of undifferentiated cells, which were identified as mesodermal or mesodermal and probably endodermal. These findings show that swimbladder has a strong and fast spreading vegetalizing effect on the responding presumptive ectoderm.
Two of 10 mug/ml cytochalasin B (CB) caused retraction of the first cleavage furrow in Triturus eggs, a spreading of the unpigmented surface from the furrow region and a flattening of the whole egg. CB appears to act against the contractility of the microfilamentous band at mid-cleavage so as to relax the furrow and also to weaken unpigmented surface to allow the egg to flatten. Uncleaved eggs and the initial formation of the cleavage groove were unaffected by CB. A fully-retracted first cleavage furrow reformed itself on transfer of the egg to normal medium but only at the time of second cleavage. Initiation of second cleavage depended upon there being sufficient of the original pigmented surface on the animal hemisphere. Tritium-labelled CB of high specific activty was prepared and used to study its ability to penetrate the surface of newt eggs during cleavage. Scintillation couting of whole eggs showed that CB was not taken into the newt egg until mid-cleavage (about 17 min after the double stripe stage) when new surface began to spread in the cleavage furrow. Fixation in glutaraldehyde and osmium tetroxide retained radioactivity in the egg, but more CB was retained after fixation in osmium tetroxide alone than after double fixation. Most of the retained radioactivity was in yolk platelets. Autoradiographs were prepared to sectioned eggs which had been fixed at late cleavage after [3H]CB had flattend the furrow. These showed that CB entered the egg through the unpigmented surface which formed in the furrow but it could not enter through the pigmented surface. The impermeability of the pigmented surface explains the observations that CB does not prevent initial furrowing at cleavage. Once inside the egg CB is transported slowly. CB penetrates to a limited extent beneath the pigmented surface from its border with the unpigmented surface in the first cleavage furrow and this seems insufficient in some circumstances to suppress the contractile phase of second cleavage.
With the aid of 3-H-uridine radioautography, the effect of gonadotropic hormone choriogonin on the synthesis of RNA in the giant granular loop of XII chromosome of the Triturus cr. cristatus oocytes was studied in normal and after pretreatment of the cells with mutagen. Choriogonin, while obviously stimulating the RNA synthesis, has no effect on the cells pretreated with mutagen.
The distribution of brain natriuretic peptide (BNP)-like immunoreactivity (ir) was studied in the brain of a urodele amphibian, the crested newt Triturus carnifex Laur. BNP-like immunoreactive neurons were found mainly in the caudal hypothalamus (retro- and supra-chiasmatic areas) and in the preoptic area. A widespread innervation throughout the brainstem as far as the spinal cord was also observed. By double immunostaining (after section incubation with a-BNP and a-tyrosine hydroxylase-TH-antibodies), close topographical relationships between BNP-like and TH-like immunoreactive neurons within the hypothalamus were found.
The effects of vitamin A on blastemal epidermis were studied during the early postamputational period of forelimb regeneration in Triturus alpestris. Vitamin A was administered through oral intubation at a dose of 250 IU per gram of body weight per day. The results were evaluated by morphometry, histology, and autoradiography. After 7, 11 and 14 days of treatment, several alterations were observed in the wound epidermis: a) reversal of keratinization; fewer keratinized cells were counted in sections from vitamin A-treated limbs; b) decrease in the incorporation of tritiated thymidine, as judged by estimation of labeling indices; c) increased mitotic activity in the cells of the stratum germinativum, and in the middle layer of the epithelial cells, as well. The significance of these cellular effects is discussed against the relevant literature.
The cytoskeletal proteins are phylogenetically well preserved in Vertebrates. However, unlike the case of Mammals, comparatively little is known about the immunocytochemical characterization of the intermediate filaments (IF) of the ependymal epithelium cells in the lower Vertebrates. The immunohistochemical response of the ependymal epithelium of the spinal cord has been examined in several poikilotherm Vertebrates. The latter were selected on the basis of the high degree of variation in adult spinal cord plasticity, a property due to the ependymal cells and probably related to different IF-associated proteins contained in them. In Triturus (Urodele Amphibian) the presence of cells having an exclusively vimentine positive cytoskeleton, apparently not organized into filamentous structures, was observed throughout ependymal epithelium. In Rana (Anuran Amphibian) the ependymal epithelium cells were found to be comparatively positive with respect to both vimentine, which was structured into cytoskeletal filaments, and glial fibrillary acidic protein (GFAP), detected using monoclonal anti-chicken-GFAP antibodies. In Lacerta (Scaly Reptile) the ependymal epithelium cells only rarely had a vimentine positive cytoskeleton and mostly appeared to stain intensely with polyclonal anti-bovine-GFAP. The different immunocytochemical response of the cytoskeleton of the ependymal epithelium cells in the poikilotherm Vertebrates examined can be explained in terms of the varying plasticity of the spinal cord. In adult animals, this plasticity is still high in the Urodeles, lower in the Anurans, much weaker in the Reptiles and disappears completely in the homeotherm Vertebrates.
In the homeotherms the presence of glial-fibrillary acidic protein (GFAP) and that of neurofilaments (NF) are used as specific molecular markers associated with intermediate filaments (IF) of the glial and neuronal elements respectively. On this basis a comparison was made between trends in the immunohistochemical response to these markers of the ependyma of a both a normal and a regenerating spinal cord in Triturus carnifex (Urodele Amphibian) adults, whose high spinal cord regenerative capacity is due to the ependymal epithelium cells. Under normal conditions, the ependymal cells are vimentin positive and negative for GFAP and the IF, respectively, while GFAP and NF positivity is found in the grey and white matter. During regeneration, by about day 10, vimentin positivity begins to decrease in the ependymal epithelium of the caudal stump and GFAP positive elements appear (subsequently, this was observed also in the ependymal epithelium of the cephalic stump). High GFAP positivity is found also in the newly formed apical ampullae. From day 20 to after day 30 these patterns develop both in the stumps and in the regenerating spinal cord. NF positivity is always restricted to the grey matter alone and to the axonal processes of the white matter. At about day 60, by which time the regenerative processes may be considered as having terminated and the spinal cord has virtually regained its original structure, the immunohistochemical features typical of the rest state are restored in the ependymal epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)
The absorption process of sugars and amino acids in the proximal tubule of the kidney is one of the typical examples of operation of bio-flow absorption systems in the living body. The relationship between two kinetic parameters of the Michaelis-Menten equation, Jmax and Kt, which are the main determinants of the reaction velocity in the absorption process, was investigated by using experimentally obtained data for several actively transported substances and a mathematical model of the proximal tubule. When examined the data of the parameters for sugars and amino acids obtained from both amphibian (Triturus) and mammalian (rat) kidneys, a distinct and common tendency was found such that a high affinity system has a low capacity and vice versa. For all substances tested in this study, the calculated concentration profile along the tubule monotonically reduced to zero at around the middle portion of the tubule, although each substance has considerably different values of Jmax and Kt. From the digital simulation, the observed Jmax-Kt relationship among the tested substances could be explained in terms of the optimality principle, by which all the systems could accomplish absorption with a sufficient reserve capacity within a limited length of the tubule. The importance of such an elaborated arrangement of the transport systems in the renal proximal tubule is discussed from the viewpoints of evolution and functional speciality of the organ.
15 days after amputation of the forelimb of young postmethamorphic Triturus vulgaris DNA-content and volume of the nuclei of the mesodermal blastema cells have been investigated in longitudinal sections of 2 microns in thickness by Feulgen-photometric and electronic determination of area. Discrimination of the DNA-synthesis phase was carried out using microautoradiography after "in vivo" labeling with tritiated thymidine. Volume and DNA-content of the nuclear sections have been found to be positive correlated. The DNA-synthesising part of the population shows characteristic differences to the mean value of volume and DNA-content of the remaining population. The factor circumference 2/area is suitable to characterize the differentiation degree of cells.
The morphology of neuromuscular junction in the amphibian submandibular muscle has been examined both light and electron microscopically. Despite the differentiation of muscle fibres into types, both the structure and ultrastructure of the motor end plates was found fairly uniform in the examined species. The strongly positive correlation between the motor end plate surface area and muscle fibre diameter was found in Triturus and Rana. Some aspects of the motor end plate morphology are discussed in connection with the results of the author's physiological and morphological observations obtained formerly.
Micropuncture technique and electron microprobe analysis have been used to investigate the role of noradrenalin in ion and water balance in the renal tubules of the lamprey Lampetra fluviatilis and newt Triturus vulgaris. Noradrenalin decreased Na, K, and Ca concentrations in the proximal lumen of the lamprey increasing the value of (TF/P)in from 1.1 +/- 0.1 to 1.3 +/- 0.1 (p less than 0.001). Regitin blocked these effects. Noradrenalin perfusion of the peritubular capillaries in newt kidney increased ion and water reabsorption in the proximal segment of the nephron and resulted in differential changes of ion transport in the distal tubule, increasing reabsorption of Na, Cl and K and inhibiting that of Ca and Mg. The rate of glomerular filtration in the nephron remained practically unaffected. The data obtained reveal direct effect of noradrenalin on the renal tubular function in lower vertebrates, this effect being realized presumably via alpha-adrenoreceptors.
In the newt [Triturus vulgaris (J.)] kidney a zone of single nephrons is distinguished, where there are ten nephrons, connected with the paramesonephral (Müller's) canal, and another zone of the renal mass; in the latter the main part of nephrons is situated, which are connected with the ureter by means of collecting tubules. In these zones of the kidney ultrastructure of epitheliocytes in the proximal and distal parts is different. The renal corpuscles of the epithelial cell in the cervical and in the intermediate parts are similar in both zones. In the zone of the single nephrons a specific peculiarity of epitheliocytes in the proximal and in the distal parts of the canaliculi is presence of numerous secretory granules in their cytoplasm. The canalicular epitheliocytes in the renal mass zone are different in the terminal and in the initial parts of the canaliculi: the former contains more mitochondria, and the area of the basolateral parts of plasmolemma is greater than those in the latter. These results are in accordance with the level of sodium ions transport in these parts of the canaliculus.
Trifluralin weakens or destroys polarity in segmentation mitoses of Triturus helveticus Raz. and Pleurodeles waltlii Michah. Previously it inhibits the cytokinesis, by reducing the activity of asters which are necessary to it. It produces chromosome abnormalities, specially involving their condensation, and makes appear discontinuities at prophase. The local thickenings of metaphase chromosomes predominate at heterochromatic regions. The action is stronger in animal than in vegetative half and this difference is highly significant. The stoppage of Amphibian eggs development states the problem of the possible action of trifluralin on the aquatic fauna.
The structure of the nephron, length of all its segments and the renal architectonics as a whole have been studied in the newt (Triturus vulgaris L.) by means of microdissection and microinjection methods. The microinjection of latex or lissamine green is performed into the blood vessels and nephrons. In one kidney 85-95 nephrons are counted, their number is not the same along the kidney length and increases in the caudal direction. There are nephrons of the ventral, intrarenal and medial populations. The length of the former is 2.7 times as great as that of the latter. A relative length of the nephron segments changes slightly. In all the ventral nephrons a nephrostome is detected. A specific peculiarity of the newt nephron that differs it from that in other vertebrates is the presence of a long distal segment, heterogeneous by its structure. Superficial canaliculi of the kidney are strictly oriented: medially to the renal corpuscles there are loops of the first part of the distal segment, they are vascularized out of the efferent veins system; laterally to the renal corpuscles the loops of the proximal, connective and second part of the distal segments are localized; they receive their blood from some branches of the afferent vein.
Histochemical studies have been made on true (AChE) and false (BChE) cholinesterases in different parts of the telencephalon of amphibians, reptiles and mammals. The data obtained indicate that the enzymic localization depends on both the level of the development of the brain and phylogenetic age of its individual formations. In the telencephalon of Ambystoma mexicanum, high concentration of AChE was found in vascular-capillary network, in other investigated amphibians (Triturus vulgaris, Rana temporaria) diffuse distribution of AChE of different intensity was observed in ancient formations of the telencephalon (septum and striatum). In reptiles (Eremias arguta, Testudo horsfieldi) undifferentiated diffuse AChE reaction is predominant in ancient parts of the cortex (septum excluded), whereas differentiated cytoplasmic localization is typical of the old and new cortex. In the brain of the lizard high BChE activity was found in the conducting pathways. Mammalian brain (rabbit, guinea pig) exhibits differentiated AChE and BChE reactions in the old and new cortex.
Specimens of Triturus cristatus carnifex (Laurenti) raised for 4 weeks in a 7 g/l solution of sodium lactate present a mean increase of about 32% in the red blood cell count in comparison to control newts raised in identically oxygenated water. 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.