Rana Dalmatina Research Articles

A family of centromeric satellite DNAs from the European brown frog Rana graeca italica.

Digestion of Rana graeca italica DNA with Asp 718I produces highly repetitive fragments of 281 and 385 bp that were cloned and sequenced. The shorter fragment corresponds to the unit repeat (RgiS1b) of a satellite DNA. The longer fragment was found to be part of a 494-bp repeat of another satellite DNA (RgiS1a) that was cloned intact as an EcoRV fragment. RgiS1b is 97% homologous to RgiS1a, from which it seems to be derived by a single deletion. Among all species tested, only the related brown frog Rana dalmatina contained homologous repetitive DNA. The overall number of RgiS1a and RgiS1b repeats per R. graeca italica haploid genome was estimated to be 2.7 x 10(5). RgiS1a and RgiS1b repeats are organized in separate arrays, but repetitive units formed by various combinations of the two repeats were also observed on Southern blots. The amount of these extra repeats varies greatly among animals from the same population, representing a rare case of individual variability in the satellite DNA organization. FISH with probes specific for both satellites, or for RgiS1a only, labeled the centromeric and pericentromeric heterochromatin of all chromosomes. This indicated that RgiS1a and RgiS1b are interspersed within the same heterochromatic regions of the chromosomes.

Phenotypic variation in metamorphosis in five anuran species along a gradient of stream influence

The respective influences of adaptation and of phylogenetic relations was investigated by comparing size and age at metamorphosis in five anuran species (Discoglossidae: Bombina variegata; Bufonidae: Bufo bufo, B. calamita; and Ranidae: Rana dalmatina, R. temporaria). All these species inhabit the alluvial floodplain of the Middle Rhône River. Within the floodplain, these species differ by the time during which water is present in their breeding habitats. Phenotypic plasticity was estimated by rearing tadpoles of each species under two different temperatures. Phylogenetic relations explained a larger part of the variation in plasticity among species than did habitat use. Bombina variegata differed from the other species in the unvariance of size at metamorphosis as temperature varied. In the other species, a langer larval period was related to a larger size at metamorphosis at the lower temperature and a shorter larval period was related to a smaller size at metamorphosis at the higher temperature. However, bivariate reaction norms showed trajectories that proved to be related to the taxonomic status of the family. We conclude therefore that adaptation to the instability of the aquatic habitat may be attributed more to the adult stage than to the larval stage. Other variables than those operating during the larval stage must be investigated to understand the distribution of amphibian communities in the floodplain. Such comparative studies can play an important role in developing and testing hypotheses about adaptative plasticity and habitat variability.

Islets and diffuse endocrine component in the pancreas of three red frogs species: relationships between endocrine and exocrine tissue

The endocrine pancreas of three red frogs was studied immunohistochemically. It consisted of islets and diffuse endocrine cells. The islets showed a mammalian-like arrangement with a central core of B cells and a peripheral mantle of A/PP cells. A few D and VIP cells were also present. Several regulatory peptides were co-localized in the same endocrine cells by consecutive sections and double-labeling studies. The A/PP cells were formed by subpopulations of cells showing various types of immunoreactivity and varying degrees of immunolabeling. Generally, glucagon/pancreatic polypeptide, glucagon/pancreatic polypeptide/peptide tyrosine tyrosine and glucagon/pancreatic polypeptide/neuropeptide tyrosine immunoreactivities were present in the islets and in the endocrine cells scattered throughout the exocrine parenchyma (the diffuse component). Some specimens, mainly belonging to Rana dalmatina, showed evident periinsular halos around the islets. The diffuse component was abundant, and mainly contained A/PP cells. It formed a net across the exocrine parenchyma; its interrelationship with the latter might occur by a paracrine mechanism.

Polecat predation on frogs and toads at breeding sites in western France

Surveys of eight radiotracked polecats (Mustela putorius) showed that they caught mainly male terrestrial anurans at spawning sites. Agile frogs Rana dalmatina formed 77.5%, whereas common toads Bufo bufo represented only 14.6% of preyed anurans. Throughout the breeding period, male anurans were found to be predominant, representing 64.8% of available agile frog and 60.7% of common toad populations in the four ponds studied. The number of male frogs was significantly higher in two ponds which were not exploited by polecats in 1990. Polecats preyed selectively on anuran males (electivity index D = 0.34 in agile frogs and D = 0.50 in toads). Thus, the intensive predation of polecats at spawning sites can influence the sex-ratio of anuran populations.

Heavy metals and pesticides in anuran spawn and tadpoles, water, and sediment

High concentrations of metals (cadmium, copper, lead, and zinc) and of lindane were measured in the sediment and in the spawn and tadpoles of Bufo bufo, Rana dalmatina, and Rana ridibunda from two Austrian locations. Residues in spawn suggest maternal transfer. Increase of the metal concentrations from spawn to advanced tadpole stage is explained by the larval microphaguous feeding habits which cause high exposition of the tadpoles to substances concentrating in sediments and suspended particles. Metal and pesticide concentrations in spawn and tadpoles are toxic to various other aquatic organisms and are furthermore considered to be potentially hazardous to the anurans themselves. The results are conform with world‐wide observations of contamination of anuran larvae with heavy metals, and prove the significance of non‐point source chemical exposure due to allochthonous toxicant input by wind load and precipitation.

Skin lesions associated with herpesvirus-like particles in frogs (Rana dalmatina).

Skin lesions associated with herpesvirus-like particles in frogs (Rana dalmatina).

Environmental factors influencing habitat exploitation by the polecat Mustela putorius in western France

Variation in habitat use was studied by radiotracking 11 polecats Mustela putorius in two wetlands in western France. Habitat selection showed a clear seasonality. Marshes were the most exploited habitat in spring while woods were mainly used in the coldest months and meadows were frequented in summer and winter. An analysis of scats showed that diet correlated with habitat utilization. The proportions of bank voles Clethrionomys glareolus, and meadow voles Microtus sp. were, respectively, related to the use of woods and meadows, while amphibians (mainly Rana dalmatina and Bufo bufo) were associated with marshes. Availabilities of rodents, assessed monthly by trapline success, were also significantly correlated to their occurrences. In contrast, no correlations were found between larger prey, such as brown rats Rattus norvegicus and rabbits Oryctolagus cuniculus, and any habitats or their abundance in the field. The occurrences of these prey and of some minor resources, such as shrews and birds, were correlated most with meteorological factors. The exploitation of marshes and amphibians increased when small rodents declined. Therefore, in the polecat, habitat selection was mostly influenced by trophic factors. Dietary diversity was greater in spring when food resources decreased, suggesting that polecats were optimal foragers. The study has emphasized that the polecat is a generalist feeder.

Accelerated female differentiation of the gonad by inhibition of steroidogenesis in amphibia

Larvae of toad ( Bufo bufo) and frog ( Rana dalmatina) were treated with 17 β C (androsten-3 one 17 β-carbossilic acid) at early stages of development in order to inhibit the activity of 5-α-reductase and to reduce the level of dehydrotestosterone, die active form of the male hormone. The effects of drug treatment on larval ovarian differentiation were analyzed at different stages in the rostral portion of the gonad of Bufo (Bidder's organ, a rudimentary ovary) and at early stages of metamorphosis in the female gonads of Rana. The Bidder's organ of experimental Bufo larvae were characterized by a considerable increase in volume and an anticipated differentiation of germ cells. In fact, oocytes of these specimens were present at earlier stages and increased in size at a faster rate than controls. The gonads of female larvae of Rana showed a much higher number of oocytes, which were also considerably larger in size. As a working hypothesis, we suggest that cells present in the larval androgenic component of the gonad may synthesize small amounts of dehydrotestosterone acting locally by diffusion upon the gynogenic component destined to produce an ovary. This hormone would inhibit ovarian development in genetic males and would regulate the time table of differentiation in genetic females. Hence the exuberant ovarian development in specimens with an induced lower level of dehydrotestosterone.

Immunocytochemical and Ultrastructural Study of Rana dalmatina PRL and GH Pituitary Cells during Larval Development

Single and double simultaneous indirect immunogold methods and ultrathin sagittal sections of Rana dalmatina tadpole heads were used to follow cytodifferentiation of PRL and GH cells in the adenohypophysial primordium from developmental stage 26 to the end of metamorphosis. Rabbit anti-frog ( Rana catesbeiana) PRL and rabbit anti-frog GH were employed in the single method, and rabbit anti-frog PRL and monkey anti-rat GH were used in the double simultaneous technique as primary antisera. At stage 27, a couple of cells with few small secretory granules immunoreactive with anti-frog GH are first identifiable. At stage 28, some cells with few membrane-bound secretory granules, 70-90 nm in diameter, and immunoreactive with anti-frog PRL and other cells with few secretory granules, 80-110 nm in diameter, and immunoreactive with anti-frog GH are present. As development progresses, differentiation in both cell types is shown by an increase in the cytoplasmic volume and in the number, size, and immunoreactivity of secretory granules. Neither comparison of adjacent ultrathin sections stained with the single labeling technique nor results of double simultaneous labeling showed the coexistence of PRL and GH within the same cell.

Reproductive activity and plasma androgen concentrations in the male ofRana dalmatina

Abstract Reproductive activity (spermatogenesis, testis and fat‐body weight, thumpad) is related to environmental factors and plasma androgen levels in the male of Rana dalmatina. The population studied, living at 1000 m a.s.l., showed a markedly discontinuous spermatogenetic cycle. From November to February, spermatogenesis stopped completely. Spermiation occurred from late February to late March. In May, there was recovery of spermatogenesis. The mating season and ovipositions took place from the end of February to late March or early April, when environmental temperatures increase and the pool where this species reproduces thaws. Significant seasonal variations were observed in the testis and fat‐body weight, thumpad epithelium, and plasma testosterone but not in plasma androstenedione. Plasma testosterone peaked in February, two months after the maximum development of nuptial callosity; however, there was a positive correlation between these two characters, which was not observed, instead, between nup...

The influence of tadpole swimming behaviour on predation by dragonfly nymphs

AbstractThis study analyses interspecific differences in anuran tadpole swimming behaviour that could influence vulnerability and therefore prey selection by dragonfly nymphs (Aeshna cyanea). Laboratory experiments showed that Bufo bufo tadpoles were almost continually and slowly in motion, which makes them easy prey for the dragonflies. Hyla arborea tadpoles were also very active and slow in swimming; in contrast to Bufo, however, they showed effective predator avoidance strategies (different habitat preferences, high evasiveness). The predation risk of Rana dalmatina larvae was low because the tadpoles were immobile and benthic, rare movements were made with high speeds. Bombina bombina is intermediate in swimming activity, velocity, and vulnerability.

A field study of survival, growth, biomass and temperature dependence of Rana dalmatina and Rana temporaria larvae

AbstractThe ecology of eggs and tadpoles of the European brown frogs Rana dalmatina and Rana temporaria was investigated in six Danish ponds. Developmental time of eggs was a logarithmic function of temperature with the same exponents for both species. However the time constant was double in the early breeding R. dalmatina so hatching appears contemporarily at the actual temperatures. Tadpole growth was fitted better by the logistic than the Gompertz function. Transformation size diverged by a factor of 2 among populations intraspecifically; this is explained by food limitation. It is suggested that interspecific competition might have contributed to present distribution. Population sizes declined exponentially. Overall survival from eggs to froglets ranged from 1.8 to 6.7 % with the highest survival in the fast-growing R. temporaria. Interspecific differences in mortality rates remained inappreciable. Since mortality does not seem to be size-limited, factors influencing developmental time might affect populations appreciably. The importance of the tadpole phase in population regulation is stressed, especially in R. dalmatina, in which survival during the first 3 month nearly equalled survival during next 33 months from froglets to adults in females.

A multivariate analysis of amphibian habitat determinants in north western Italy

AbstractThe distribution of Bufo bufo, Rana esculenta complex, Rana dalmatina, Hyla arborea, Triturus carnifex and Triturus vulgaris were studied in 61 ponds in NW Italy, in relation to a number of specific habitat features. Multivariate analysis identifies those habitat parameters which classify ponds into characteristic habitat groups. Several multivariate statistical tests were carried out to identify habitat features characteristic of each species and to delineate ecological factors that influence amphibian distributions and size of breeding populations. Variables scored at each pond were: extent of aquatic vegetational cover, age of the pond, terrestrial habitats occurring near the ponds, degree of human interference, surface areas, maximum depth, chemical water factors (such as pH and water hardness). The first four of these parameters influenced breeding population presence of R. dalmatina, H. arborea, T. vulgaris and T. cristatus significantly. Densities of H. arborea, R. dalmatina, B. bufo and R. esculenta were apparently unaffected by any of these parameters; these species seem to colonize available habitats almost at random.

Localization of the nucleolar organizer and heterochromatin evolution in three European brown frogs: Rana dalmatina, Rana graeca, Rana iberica

AbstractThis study investigates the karyotypes, genome sizc, constitutive heterochromatin, and NOR localization in three European brown frog species: Rana iberica, R. dalmatina and R. graeca. The three species all possess a karyotype of 26 chromosomes. The genome size is respectively 6.9, 9.7 and 11.3 pg/N in R. iberica, R. dalmatina and R. graeca. Constitutive heterochromatin is 1.7% in R. iberica, 3.1 % in R. dalmatina and 7.0% in R. graeca. The NOR is located on the long arm of the 10th chromosome in R. iberica and R. graeca, whereas it is pericentromerically localized on the short arm of the 3rd chromosome in R. dalmatina. A single NOR extrasite is found in R. graeca. Results suggest that European brown frogs have evolved independently from North American and Asian groups. Moreover, the variation observed in constitutive heterochromatin is informative of different amplification levels of satellite-like DNA. Data also suggest that in R. dalmatina NOR localization on the 3rd chromosome may be derivcd by amplification of a pre-existing NOR site.

Toxicity of an Anionic Detergent to the Spawn and Larvae of Anurans (Amphibia)

AbstractSeveral experiments were performed to test the toxicity of FIT, a washing‐up and general cleaning liquid containing about 10 % sodiumalkanemonosulfonate (industrial name E 30) to spawn and larvae of anura. The LC50 values for spawn were between 1.62 × 10−3 % (Rana dalmatina) and 4.97 × 10−3 % (Rana temporaria). The sensitivity of anuran larvae depends on the concentration and duration of exposure to the detergent as well as on the developmental and differentiation stage of the organisms. The toxicity of FIT is not due solely to the alkanesulfonate it contains, but results from the joint action of the surfactant, polyphosphates and solvents.The results indicate that detergents may be harmful to the amphibian fauna of Central Europe.

Direct Evidence for in vitro Binding of a Lectin from Arachis hypogea to Endoblastic Primordial Germ Cells of Amphibian Embryos: (Peanut-agglutinin binding primordial germ cells/embryos/Amphibian).

Peanut agglutinin was previously shown to have a specific affinity for primordial germ cells (PGCs) from anuran amphibian embryos. For separation of these cells from endoblastic ones, suspensions of dissociated cells from the endoblastic masses of Xenopus laevis and Rana dalmatina embryos were treated with peanut agglutinin. This treatment resulted in agglutination of a small number of cells, and these aggregates were separated from unaggregated single cells by gravity in 50% calf serum medium. Histological and ultrastructural analysis of numerous sections of the aggregated cells showed that they contained the germinal plasm characteristic of PGCs. The specificity of the PGCs agglutination was confirmed by disocciation of the aggregates with 0, 2 M D-galactose solution. This embryonic cellular population of PGCs should be useful in further in vitro experiments.

Studies on the biology of the frog Rana dalmatina BONAPARTE during the breeding season in Greece (Amphibia: Anura: Ranidae)

Abstract Studies on the biology and ecology of Rana dalmatina during its breeding season have been performed in the region of Gallikos river for some years. Animals hibernated in their home range. They emerged from hibernation shortly before the onset of oviposition. Spawning period ranged from the 25th of January to the 15th of March, depending on the weather conditions. In some years it was continuous with 1-3 peaks of oviposition, in others interrupted for shorter or longer time periods depending on the temperature. The mean numberofeggs per female estimated in 190 egg masses was 985 (445-1761) and the mean diameter of the eggs measured in samples from 20 different egg masses was 1.78 mm (1.49-2.04). The mean diameter of the eggs was positively correlated with the number of eggs in each egg mass.

The effect of gamma- L-glumatamyl-taurine (litoralon) on the amphibian metamorphosis

1. Prolonged litoralon treatment of Rana dalmatina beginning with stage 28 of its development accelerated the resorption of the tail fin, further shortened the body-length, and enhanced the appearance of the limb buds. 2. Beside this enhancement of early metamorphosis, litoralon retarded the ossification and reduced the spontaneous mortality during developmental stages 28–30 of the experimental animals.

Repression by puromycin of testosterone-induced sex reversal in Rana dalmatina tadpoles

Repression by puromycin of testosterone-induced sex reversal in Rana dalmatina tadpoles

Repression by actinomycin D of testosterone induced sex reversal in Rana dalmatina tadpoles

Repression by actinomycin D of testosterone induced sex reversal in Rana dalmatina tadpoles