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At least 613 records · Page 34Linked to original sources
PubMed2000

Chromosomal studies on five species of the genus Leptodactylus Fitzinger, 1826 (Amphibia, Anura) using differential staining.

Cytogenetic studies were carried out on five species of Leptodactylus, namely L. fuscus, L. notoaktites, L. labyrinthicus, L. ocellatus, and L. podicipinus, after standard staining, Ag-NOR and C-banding as well as BrdU incorporation for three of them. The species had 2n = 22 chromosomes and two basic karyotype patterns. Chromosome 8 was a marker bearing a secondary constriction. In all species, this secondary constriction corresponded to the Ag-NOR site. The species had centromeric C-bands in all chromosomes of the complement, but some interstitial or telomeric bands seemed to differentiate some karyotypes, either at the species or the population level. In L. ocellatus, the C-banding pattern confirmed the occurrence of a heteromorphic pericentric inversion in chromosome 8 in specimens from one of the populations. The BrdU incorporation technique showed no detectable difference in the replication patterns of the major bands in the chromosomes of L. notoaktites, L. labyrinthicus, and L. ocellatus.

Animals↗
PubMed2001

Spermiogenesis in Melanophryniscus cambaraensis (Amphibia, Anura, Bufonidae): ultrastructural and cytochemical studies of carbohydrates using lectins.

Spermiogenesis in the bufonid Melanophryniscus cambaraensis was analysed ultrastructurally. The nucleus of spermatids undergoes morphological modifications divided into five distinct stages based on chromatin condensation. The acrosomal vesicle differentiates into an acrosome and a subacrosomal cone, which cap the anterior region of the nucleus. The spermatozoa consist of the head with a nucleus and acrosomal complex and the tail, with an axoneme, an axial rod and an undulating membrane. The participation of several carbohydrate moieties during this differentiation process was detected using various gold-labelled lectins.

Animals↗
PubMedDate not supplied

[Analysis of the structural features of the sperm chromatin of amphibia].

Deoxyribonucleoproteid (DNP) organisation of the sperm from amphibian species (Rana temporaria, Triturus vulgaris, Bufo bufo) with different sperm chromosomal basic proteins has been analysed by nuclease fragmentation. Electrophoretic distribution of chromatin fragments reveals regular organisation of DNP in the sperm of the species investigated. In spermal DNP of the frog Rana temporaria, 3 sub-fractions of histone H1 were found. In the sperm of the newt Triturus vulgaris and the toad Bufo bufo, abundant arginin-rich histones H3 and H4 as well as the presence of low molecular weight protamine-like proteins were noted. Spermal chromatin of all the species studied exhibits high content of chromosomal RNA which is resistant to the effect of exogenous RNAse.

Animals↗
PubMed2001

[Cranial bone neoplasm in early triassic amphibia].

A neoplasm in cranial bone of an early Triassic amphibian has been investigated. Although no tissue has survived, the cranial flat bone is similar to that in living animals of the same class. Evidence is presented in support of a hypothesis that the neoplasm is a skeletal tumor which consists of non-functional bone and looks like an atypical tumorous bone of skeletal origin. It was identified as a parostotic osteosarcoma on the basis of macro- and microscopic and X-ray examination.

Amphibians↗
PubMed2001

[Various effects of prostaglandin E2 on reabsorption of water and urea in the amphibia osmosis-regulating epithelium].

Principal similarities between molecular pathways providing the enhancement of water and urea reabsorption under the action of argininvasotocin (AVT) in amphibian urinary bladder suggest that prostaglandin E2 (PGE2) could be a negative regulator of urea transport. To analyse this hypothesis, the role of PGE2 in regulation of urea transport was studied in isolated frog (Rana temporaria L.) urinary bladder. The urea permeability (Pu) was determined from the rate of efflux of (14) Curea from mucosal to serosal solution in isoosmotic conditions. The water permeability was measured in separate experiments in presence of an osmotic gradient. In contrast to water permeability, we were unable to demonstrate any inhibitory effect of 10-1000 nM PGE2 on AVT-stimulated urea transport using a variety of protocols. It was found that basolateral PGE2 exposure (10 nM-1 microM) caused an increase in Pu with no effect on osmotic water flow. The PGE2 effect was markedly inhibited by phloretin, a specific inhibitor of urea transporter. Sulprostone, an EP1/EP3 prostaglandin E2 receptor agonist, had no effect on Pu suggesting the contribution of EP2/EP4 receptor subtypes. In presence of osmotic water flow, the AVT-induced urea transport was significantly higher. This water flow-dependent urea permeability was inhibited by PGE2 although the inhibitory effect was less pronounced in comparison to the action of PGE2 on osmotic water flow. On the basis of these results we can make a conclusion that PGE2 has different role in regulation of water and urea transport in the frog urinary bladder. PGE2 could be considered as a stimulator of urea transport and an inhibitor of osmotic water flow activated by the AVT. The ability of PGE2 to regulate various types of cAMP-dependent transport by different mechanisms seems to be based on the presence of multiple basolateral PGE2 receptor subtypes in amphibian osmosis-regulatory epithelium.

Absorption↗
PubMed1975

Progesterone-induced in vitro maturation in oocytes of Notophthalmus viridescens (Amphibia Urodela) and some observations on cytological aspects of maturation.

Maturation in vitro of oocytes of the newt, Notophthalmus viridescens, is inducible with progesterone after in vivo treatment of females with gonadotropin; few oocytes mature in vitro in the absence of such gonadotropin treatment. Chromosomes of most large oocytes of animals not receiving gonadotropin are still in the lampbrush condition; chromosomes from gonadotropin-treated animals are shorter and the lateral loops are less profuse and somewhat retracted. The chromosome condition, then, can be correlated with susceptibility to progesterone induction of maturation in vitro. As maturation progresses, the germinal vesicle moves toward the surface and decreases in size, with an apparent loss of nuclear material from the centripetal end. Although lateral loops of most chromosomes disappear during the changes in the germinal vesicle, profuse loops develop during this period at the sphere loci, which were previously devoid of loops.

Animals↗
PubMed1979

[Invariability of the H-Y antigen expression in the heterogametic sex of some amphbians and evidence for sexual dimophrism of the antigen expression in Pelodytes punctatus D (Amphibia, Anura)].

The H-Y antigen is studied in some Amphibians whose sexual genetic constitution is known. Thus, in Pelurodeles waltlii, Ambystoma mexicanum, Xenopus laevis and Rana ridibunda, the invariability of the H-Y antigen expression in the heterogametic, sex is confirmed. In Pelodytes punctatus the genetic sex is unknown but the existence of the H-Y antigen in phenotypic males leads to the conclusion of a male heterogamety of the XY type.

Ambystoma↗
PubMed2002

[The glands of the dorso-distal mucosa of the toad Bufo marinus (Amphibia: Anura) tongue: histology and ultrastructure ].

Frequently, the studies on the lingual epithelium ultrastructure in anurans do not show differences between filiform papilae and glandular epithelia in the non-sensory dorsal epithelium. To accomplish the study of glandular epithelium, samples of dorso-distalis mucosae of Bufo marinus tongue were processed for transmission electron microscopy and also semithin sections of the same material were used for light microscopy study. The results showed that the glandular epithelium is constituted by three different types of cells: (1) serous granular secretory cells; (2) mitochondria rich cells (CRM); and (3) ciliated cells. Detailed structures of each type of cell under light and electron microscopy were given. Notably, in the lingual portion studied, secretory cells showed no signs of exocytosis of their granules, thus suggesting that they do not have a basal or continuous rate of secretory activity. Additionally, the distribution, localization and structure of CRM in the gland epithelium suggest their participation in secretory cell maturation and/or function.

Animals↗
PubMed1975

[Significance of olfaction in the feeding behavior of toads (Amphibia, Anura, Bufonidae): studies with the natterjack (Bufo calamita Laur.)].

The influence of olfactory and visual prey stimuli on the feeding behaviour of toads was studied as well as their response to lasting olfactory cues. A further aim was to find simple methods for testing olfactory responsiveness in anurans. Subjects were 8 adult specimens of the European species Bufo calamita (natterjack) kept in captivity one year at least. The results point to the rôle of olfaction in these animals.

Animals↗
PubMed1975

[Epidermal ball cells of the Ascaphus truei Stejneger (Amphibia, Salientia, Ascaphidae) larva: a biometric contribution].

1. With regard to orientation the in the larva of Ascaphus truei characteristic excretory special cell (mucosa cell) was analysed in plain preparations of epidermis from head-trune in four test regions - praeoral, postoral, craniodorsal and post spiracle -, the speciman (stage 32 according to Gosner 1960) being investigated was excellently fixed, 50 cells at times biometrically are used therefore. The element with adequate safety must be called ball cell because of its shape. 2. Elements only praeoral present a more little volume dividing from other average (and more unimportant occurence of an outlet). In respect of frequency distribution of different big ball cells in whole material significant differences are missed. A definite size of volume independent of region is prefered. 3. In 69% of all ball cells being considered there is an outlet, the existence is not fixed to a definite volume of cell. Shape of opening in 88% is round to a little ellipsoidal, its size is reaching to 10% more than half of maximal flat plain of cells; with regard to regions differences are absent. 4. In 3 regions thereupon being investigated (postoral, craniodorsal and post spiracle) a real correlation exists between height of single ball cells and thickness of epidermis.

Amphibians↗
PubMedDate not supplied

Serous cutaneous glands of the western spade-foot toad Pelobates cultripes (Amphibia, Anura): an ultrastructural study on adults and juveniles.

The venom glands of the western spade-foot toad Pelobates cultripes were studied under light and electron microscopes. The glands exhibit the structural patterns usual in anurans, including the typical secretory syncytium. The peripheral cytoplasm contains a single row of nuclei and secretory organelles related to proteosynthesis. The inner cytoplasm is filled with large vesicles holding a thin product which originates from the merging of smaller ones containing a thicker material derived from the Golgi apparatus. The appearance and maturation of P. cultripes venom have been compared with patterns of biosynthesis and secretory evolution described in serous cutaneous glands of several anuran species. Following these criteria, the traditional trends in the terminology and classification of serous glands in anuran skin are discussed and reviewed.

Amphibian Venoms↗