Newt Triturus Cristatus Carnifex Research Articles

Consequences of splenectomy on the compensatory mechanism of cutaneous respiration in the newt

AbstractThe spleen of the newt Triturus cristatus carnifex (Laurenti) hoards erythrocytes when the animal is well oxygenated and releases these into circulation when the animal becomes hypoxic. This mechanism allows the newts, amphibians with prevalently cutaneous respiration, to adapt to both environmental and metabolic changes.Splenectomized specimens were anesthetized with chlorbutol (to eliminate movement and lung respiration) and observed in five different conditions: at 18°C in humid air, stirred water, and still water, and at 6°C and 33°C in humid air. The study demonstrates that the newt does not have substitute sites for erythrocyte accumulation. However, though the spleenless specimens are incapable of controlling their cutaneous oxygen supply, they can regulate their blood volume, which diminishes with decreasing temperature causing marked variations in the erythrocyte concentration and hematocrit value.The splenectomized specimens, raised for over a year at 18°C, present typically steatosic livers, with lipid droplets and extremely low hepatocyte glycogen levels, indicating a state of chronic hypoxia due to the prevalently aquatic habits of the newt. In fact, the spleenless newts have significantly fewer erythrocytes (P < 0.001) than the unoperated animals‐‐a total volume of 2.27 ± 0.46 ml per 100 g of body weight compared to 2.74 ± 0.29 (mean ± standard deviation). The limited quantity of erythrocytes can provide adequate oxygen only at low temperatures and in an airy environment or in moving water, while an immobile animal in still water undergoes hypoxia due to the formation around it of an hypoxic =diffusion boundary layer= caused by the low coefficient of oxygen diffusion in water. © 1993 Wiley‐Liss, Inc.

Splenic respiratory compensation and blood volume in the newt

In the newt Triturus cristatus carnifex, reversible increase in size of the spleen is linked to the respiratory state of the animal: when the newt is exposed to the air, and thus well oxygenated, the spleen hoards erythrocytes; when immersed in still water, in an hypoxic state, the spleen releases erythrocytes into the bloodstream. In chlorobutanol‐anaesthetized specimens exposed to the air, the maximum size reached by the spleen diminishes with a rise in temperature up to the disappearance of all congestion at 33°C. The blood volume of newts kept in humid air at 6°C and 18°C after anaesthesia varies from about 6–9 ml per 100 g of body weight, while the red blood cell count and haematocrit value remain stable. In anaesthetized specimens kept in still water at the same temperatures the blood volume is stable, at about 7 ml per 100 g, but the red cell count and haematocrit are notably higher. At 33°C, a critical temperature for the newts, the specimens in still water succumb while those in air present the same blood volume as at 18°C, but have a higher erythrocyte count and haematocrit value.

Immunocytochemical identification of growth hormone- and prolactin-producing cells in the hypophysis of the newt Triturus cristatus carnifex Laur

Single indirect immunocytochemical methods (immunofluorescence, PAP, and ABC) and double sequential staining (ABC followed by immunofluorescence) were used to localize GH- and PRL-producing cells in the pituitary distal lobe from Triturus cristatus. The following antisera were employed: rabbit anti-ovine PRL, anti- Rana catesbeiana PRL, anti-ovine GH, anti-bovine GH, and monkey anti-rat GH. A cell population corresponding to type-2 acidophils localized in the dorsal and central region, under the intermediate lobe, immunoreacted with GH antisera. Both ovine and bullfrog PRL antisera labeled a large cell population, corresponding to type-1 acidophils, predominantly localized in the ventral anterior two-thirds of the gland. The pattern of localization shown by the two cell types, although consistent with the majority of data on adult amphibians, disproves the findings obtained on the same species by other authors.

Effect of temperature on the splenic mechanism of respiratory compensation in the newt

AbstractThe spleen of the newt Triturus cristatus carnifex (Laurenti), an urodele amphibian, hoards erythrocytes when the animal is well‐oxygenated and releases them into the bloodstream when the animal is in a hypoxic condition. Between the extremes of congestion and decongestion the weight of the spleen varies up to a ratio of 6:1. However, the degree of the phenomenon depends on the temperature, which, in ectotherms, regulates metabolic rate and thus oxygen demand. In order to assay the degree of hypertrophy reached by congested spleens in standard respiratory conditions, groups of eight animals—previously anesthetized by immersion for 20 minutes in a 0.2% solution of chlorbutol in tap water at 18°C—were exposed to 100% humid air in a thermostatic chamber set at a temperature of 6, 12, 18, 24, 27, 30, or 33°C. Each animal remained at the set temperature until surpassing the minimum time necessary for maximum hypertrophy to be reached, equal to the time necessary for 4,000 heartbeats. At 33°C the spleens are almost completely bloodless, while at the other temperatures their hypertrophy from congestion increases linearly as the temperature diminishes, reaching maximum values at 6°C. Though the progressive congestion of the spleen as the temperature descends is due mainly to blood cells and only very slightly to plasma, erythrocyte concentration in the blood remains constant at all the lower temperatures up to that of anesthesia (18°C); this phenomenon implies variability of blood volume in the newt. Instead, above 18°C, the values of the hematic parameters increase as the temperature rises, reaching a maximum increment of about 30% by 27°C.

Effect of spleen congestion and decongestion on newt blood

Experiments on the newt Triturus cristatus carnifex have shown that the spleen of specimens, either anaesthetized with chlorobutanol or in a normal condition, stores red blood cells when the animal is well oxygenated and releases these into circulation under conditions of hypoxia. The extreme limits of congestion and decongestion, commonly encountered in nature, can be obtained in the laboratory by exposing the animals to the air or by immersing them in still water. During the shift from a congested to decongested state, the spleen is reduced to less than one‐fifth of its weight, while the erythrocyte concentration and correlated parameters in the blood stream increase by more than 60%. Splenic regulation of the circulating erythrocyte concentration compensates not only for variations in oxygen supply linked to environment, it may also compensate for the cyclical variations in red cell production of this amphibian, whose erythropoietic tissue activity is intermittent and subject to seasonal variations.

Location of nuclear proteins on the chromosomes of newt oocytes

IN eukaryote cells chromosomal proteins are responsible for the organisational state of the DNA and the control of genetic expression, therefore knowledge of their location is an essential prerequisite for understanding chromosome function. Cytological localisation of chromosomal proteins is feasible using cells with giant chromosomes such as the oocytes of the newt Triturus cristatus carnifex where there are clearly defined regions active in RNA transcription (the loops) and regions containing most (>95%) of the DNA in a condensed state (the chromomeres)1. There are two main classes of protein associated with chromosomes: histones, which are generally considered to be complexed with the sugar-phosphate backbone of the DNA2; and nonbasic proteins which are constituents of metabolically active chromatin3.

The ultrastructure of the pars distalis of the hypophysis in males of Triturus cristatus carnifex Laur., treated with the antiandrogen cyproterone acetate.

The adenohypophysis of the newt Triturus cristatus carnifex Laur. shows three types of cells: 1) cells with granules of about 350–550 mμ in diameter, 2) cells with small granules of 200–250 mμ in diameter and globules with a cristal-like arrangement containing cylinders with a diameter of about 960 A and 3) cells containing small granules only. The AA. discuss the ultrastructural changes of the gland and the modifications of sexual secondary characters (S.S.C.) in animals given Cyproterone acetate (1/2 mg every three days). The animals have been treated for a period of time varying between 3 and 5 months, starting in October-November, when S.S.C. begin to develop again. At the end of the treatment the newths showed a loss of S.S.C., and the ultrastructure of the adenohypophysis resembled that of castrated animals, i.e.: great swelling of R.E.R. and partial degranulation of glycoprotein secreting cells which contain the 200 mμ granules and the globules. The S.E.R. showed also swelling and hyperactivity.

The counterbalancing effect of follicle-stimulating hormone on the antigonadal activity of prolactin in the male newt Triturus cristatus carnifex (Laur.).

The counterbalancing effect of follicle-stimulating hormone on the antigonadal activity of prolactin in the male newt Triturus cristatus carnifex (Laur.).

Morphological variability and its physiological origin in oocyte nuclei of the crested newt

ABSTRACT The effects of hypophysectomy and of subcutaneous injection of gonadotrophin upon whole oocytes, oocyte nuclei, and lampbrush chromosomes of the newt Triturus cristatus carnifex have been studied. Hypophysectomy leads to a reduced rate of incorporation of 32P into the whole oocytes and oocyte nuclei. Large, yolky oocytes are more severely affected than are small oocytes lacking yolk. Hypophysectomy also leads to decreased stiffness of oocyte nuclear sap, change in the number and character of free granules in the nuclear sap, and alteration in the size of certain objects occurring at specific sites on the lampbrush chromosomes. Injection of mammalian gonadotrophin leads to an increased rate of uptake of 3aP into the cytoplasm and nuclei of yolky oocytes. Gonadotrophin treatment also leads to increased stiffness of oocyte nuclear sap, decrease in the number and/or the size of free granules in the nuclear sap, reduction in size of the giant loops of chromosomes X, XI, and XII, and changes at the axial granule loci of chromosome I and the sphere loci of chromosomes V and VIII. Each of the features mentioned above varies in nature from one animal to another. This inconstancy, which is superimposed upon stable genetic characteristics and upon those developmental changes which normally accompany oocyte growth, is now shown to reflect differences in the physiological states of the ovaries of different newts.

The contribution of the chromosomes to the telophase nucleus in cultures of fibroblasts of the adult crested newt Triturus cristatus carnifex

1. 1. The course of early telophase has been studied in living and fixed cultures of fibroblasts of the adult crested newt Trituras cristatus carnifex. 2. 2. The pairing of anaphase chromosomes, previously reported, is of irregular occurrence and was infrequent in the material used in the present studies. 3. 3. Each chromosome in anaphase contained two plectonemically entwined helical chromonemata. 4. 4. At the end of anaphase the chromosomes were broader and shorter than at any other time, and either touched each other within each daughter group, or were joined by material containing desoxyribonucleic acid, to form a continuous clump; anaphase pairing is probably the first stage of clumping, affecting the first chromosomes to make contact with each other. 5. 5. As the clumped chromosomes separated, strands of material, clearly visible in life and containing desoxyribonucleic acid, remained between them. 6. 6. At the same time it could be seen that the nuclear membrane had formed in a position corresponding to the boundary of the clumped group. 7. 7. After the period of clumping the chromonemata relaxed into irregular relational coils longer than the helices from which they were derived. At this stage the chromonemata of a chromosome were separated by as much as 1 μ and were clearly seen in the living cell.

Preliminary Account of an Electron Microscope Study of Chromosomes from Newt Oocytes

ABSTRACT Chromosomes from oocytes of the newt Triturus cristatus camifex have been photographed by means of the electron microscope. These chromosomes are shown to consist of single axial filaments, approximately 200 Å wide, with ‘lamp-brush’ loops attached at intervals along their lengths. Good fixation of the lamp-brush loops has not yet been obtained. These chromosomes are attached in pairs to their homologues at points which, in the past, have been considered to be chiasmata: it has been assumed that the stage is diplotene of the first meiotic division. The singleness of the chromosome strands which we have observed is at variance with observations of diplotene in other material by means of the light microscope.