Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FROGS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources
PubMed1985

Changes in 3H-leucine enkephalin binding in spinal cord of frog after dorsal rhizotomy, cordotomy, transcutaneous stimulation and temperature variations: correlation with nociceptive sensitivity.

In the frog spinal cord about 50% of the 3H-leucine enkephalin (3H-LE) binding sites (b.s.) were blocked by an endogenous ligand. Three days after deafferentation and cordotomy the number of free b.s. increased by 44 and 56%, respectively. In spinal frogs the threshold of the flexor reflex responses evoked by nociceptive stimuli decreased. More than 7 days after deafferentation and cordotomy the number of both total and free 3H-LE b.s. decreased, while the threshold of the flexor reflex responses returned to that before spinalization. Transcutaneous electrical stimulation (TES) of the hind limbs (30 Hz, 5 minutes) in frogs spinalized 3 hours earlier increased 3H-LE binding at low intensities of stimulation (0.2 mA) and decreased the threshold of the flexor reflex responses. TES at higher intensities (1.0 mA) decreased 3H-LE binding and increased the threshold. Three days after spinalization TES even at low intensity diminished 3H-LE binding and raised flexor reflex threshold. A decrease in the number of free 3H-LE b.s. was found when the frog body temperature was elevated (from 15 to 24 degrees C) or lowered (from 15 to 1 degrees C) for 14 days and was accompanied by an increase in flexor reflex threshold. The data suggest the existence of an endogenous opioidergic system in the frog spinal cord which has a high degree of tonic activity.

Animals↗
PubMed1978

The effects of four arthropod diets on the body and organ weights of the leopard frog, Rana pipiens, during vitellogenesis.

Wild-caught adult Rana pipiens females were captured in midsummer and fed diets of crickets, flies sowbugs or wax moth larvae during a three-month period of active vitellogenesis. The cricket diet supported the most extensive body weight gain during this time and promoted a prolonged period of weight increase in an additional long-term study. Synchronous growth of the oocytes occurred in all four groups, but the ovaries and oviducts of cricket-fed animals were significantly larger than those of frogs on the other three diets. The significantly higher liver weights of frogs fed wax moth larvae may have reflected an augmentation of hepatic energy stores. Fat body weights were also highest in this group of animals. Frogs fed crickets and wax moth larvae possessed larger fat bodies than did the midsummer control animals killed immediately after their arrival in the laboratory. In contrast, frogs fed flies and sowbugs had smaller fat bodies than did the initial controls, suggesting that animals on these diets had utilized fat body lipid during vitellogenesis. Gastrocnemius and final body weights were lowest in frogs fed wax moth larvae. These findings may have reflected the nutritional content of the diet or the reduction in appetite frequently noted in these animals during observations of feeding behavior.

Animals↗
PubMed1979

[Comparative study of D-glyceraldehyde-3-phosphate dehydrogenase from frog and pike skeletal muscles].

The purified preparations of glyceraldehyde-3-phosphate dehydrogenase isolated from frog and pike skeletal muscles were found homogenous under polyacrylamide gel electrophoresis. Their amino acid composition is similar to that of glyceraldehyde-3-phosphate dehydrogenase from other animal species. The interaction kinetics for frog and pike glyceraldehyde-3-phosphate dehydrogenase SH-groups with 5,5'-dithio-bis-(2-nitrobenzoate) (DTNB) were studied. A negative correlation between the thermal stability of the enzyme preparations from pig, pike, lamprey and frog muscles and the reactivity of their SH-groups with respect to DTNB was observed. NAD at saturating concentrations was found to protect the enzyme from lower vertebrates muscles against thermal inactivation in a lesser degree than does the pig muscle enzyme. The weaker protective effect of NAD was observed for lamprey and frog enzyme preparations, which are characterized by a low SH-group reaction ability. Frog and pike apoenzymes are considerably more resistant to trypsin proteolysis than the pig apoenzyme.

Amino Acids↗
PubMed1979

The extracellular compartments of frog skeletal muscle.

1. Detailed studies of solute efflux from frog sartorius muscle and single muscle fibres were carried out in order to characterize a 'special region' (Harris, 1963) in the extracellular space of muscle and determine whether this 'special region' is the sarcoplasmic reticulum. 2. The efflux of radioactive Na, Cl, glusose, 3-O-methylglucose, xylose, glycine, leucine, cycloleucine, Rb, K, inulin (mol. wt. 5000) and dextran (mol. wt. 17,000) from previously loaded muscles was studied. In all cases except dextran the curve had three components, a rapid (A) component which could be equated with efflux from the extracellular space proper, a slow (C) component representing cellular solute and an intermediate (B) component. The distribution space for the B component was 8% of muscle volume in summer frogs and 12% in winter frogs and appeared to be equal for all compounds studied. We tested the hypothesis that the B component originated from the sarcoplasmic reticulum. 3. The C component was missing from the dextran curves. Both dextran and inulin entered the compartment of origin of the B component (compartment B) to the same extent as small molecules. 4. For all compounds studies, the efflux rate constant for the A component could be predicted from the diffusion coefficient. For the B component the efflux rate constant was 6--10 times slower than that for the A component but was still proportional to the diffusion coefficient for the solute in question. 5. When Na and sucrose efflux from single fibres was followed, a B component was usually observed. The average distribution space for this component was small, averaging 1.5% of fibre volume. There was no difference between the average efflux rate constants for Na and sucrose. 6. In an appendix, the constraints placed on the properties of a hypothetical channel between the sarcoplasmic reticulum and the T-system by the linear electrical parameters of frog skeletal muscle are derived. It is shown that the conductance of such a channel must be less than 0.06 x 10(-3) mohs/cm2 of fibre membrane. 7. The conductance between compartment B and the extracellular space can be calculated from the efflux rate constants for Na, K and Cl. The value obtained was 5 x 10(-3) mhos/cm2 of fibre membrane or 100 times the limiting value for the conductance of the T-SR junction. 8. The finding that there is a B component in the efflux curves for large molecular weight substances like inulin and dextran and the small size of the B component in efflux curves from single muscle fibres indicate that the 'speical region' of the extra-cellular space of frog muscle is not the sarcoplasmic reticulum. This conclusion is confirmed by a calculation of the conductance between the B compartment and the extracellular space. The value obtained is incompatible with predicted electrical properteis of the SR-T-tubule junction...

Animals↗
PubMedDate not supplied

[Comparison of the cholinoreceptor and cholinesterase properties of the frog Rana temporaria and the squid Todarodes pacificus].

Studies have been made on the interaction of several groups of quartenary ammonium salts with cholinoreceptors of m. rectus abdominis of the frog Rana temporaria, and isolated m. retractor infundibuli of the octopus Todarodes pacificus, as well as with cholinesterases of the frog brain and visual ganglia of the octopus. The derivatives of polymethylene bis(trimethylammonium) compounds, being cholinomimetic drugs for frog muscle, do not exert cholinomimetic influence on octopus muscle. The same difference with respect to their effect on frog and octopus receptors was found in anabazin derivatives. Among amide derivatives of acetylcholine, the strongest mimetic effect on cholinoreceptors of both animals was exhibited by a piperazine isolog with gauche-conformation, whereas N-methyl isolog with trans-conformation was found to be the strongest inhibitor of cholinesterases. Cholinoreceptors and cholinesterase of the octopus were less sensitive to the effect of the investigated quartenary ammonium salts than those of the frog.

Abdominal Muscles↗
PubMed1983

A new occupational allergy due to frogs.

This report describes an extremely rare case of occupational allergy that developed in a frog handler. A 31-year-old female laboratory technician developed itching and urticaria one year after she began handling frogs and extracting their brains in the laboratory. Nine years later she noticed swelling of the right hand, stridor and dyspnea when she mistakenly injected her finger with a needle contaminated with extracts of frog brain. Specific IgE antibody to frog extracts was demonstrated by RAST and by P-K testing. However, no specific IgG antibody was found by agar gel diffusion or in heterologous PCA testing using guinea pigs. We suggest that allergic symptoms in this case were due to the development of Type I allergic reactivity to frog antigens.

Adult↗
PubMed1982

[Structural differences in the collagens of Rana frog species with dissimilar temperature ecology. The contribution of carbohydrate components to collagen molecular thermostability].

Skin procollagens in two species groups of frogs of the genus Rana - brown frogs (4 species) and green frogs (3 species) distributed in European and Asiatic parts of the USSR have been compared. A geographic intraspecific variation in collagen characteristics (two geographic populations of the pond frog Rana nigromaculata) is revealed. Intergroup differences in the thermal denaturation of collagens established by means of methods of circular dichroism and microcalorimetry are significant. Such differences within both the groups are not so visible. With the species studied, carbohydrate components contents in procollagen vary. Interspecific differences in the procollagen thermostability correlate with the thermal ecology of frogs and seem to be associated with the availability of carbohydrates.

Animals↗
PubMed1995

Evaluation of use of tiletamine/zolazepam for anesthesia of bullfrogs and leopard frogs.

Use of tiletamine hydrochloride and zolazepam hydrochloride (1:1 fixed ratio combination) as an anesthetic agent in 2 anuran species was studied. A dosage of 5 mg/kg of body weight, administered IM, resulted in variable weak tranquilization. Intramuscular administration at dosages of 10 and 20 mg/kg induced variable states of tranquilization or anesthesia in leopard frogs (Rana pipiens) and bullfrogs (R catesbeiana). The dosages of 50 mg/kg induced anesthesia with greater consistency than lower dosages in bullfrogs, but resulted in mortalities. The same dosage was uniformly fatal in leopard frogs. Neither gross nor histologic lesions were identified in the frogs that died. Depth and duration of anesthesia was dosage related. At the 20 and 50 mg/kg dosages, leopard frogs attained a greater depth of anesthesia and remained anesthetized for a significantly greater duration than did bullfrogs; however, at the 5 and 10 mg/kg dosages, bullfrogs developed greater tranquilization for longer periods than did leopard frogs. Results of this study revealed profound intraspecies variation in depth and duration of effect of tiletamine/zolazepam; therefore, the drug does not appear to be a suitable injectable anesthetic in anurans.

Anesthesia, General↗
PubMed1976

[Melanotropic hormone in the green frog (Rana esculenta): biochemical and radioimmunological study].

The alpha-MSH levels in the frog hypophysis were measured by use of a sensitive ans specific radioimmunoassay. Sephadex G-50 gel chromatography of frog pars distalis and pars intermedia extracts showed that frog hypophyseal MSH was chemically related to synthetic alpha-MSH. Rat tissue homogenates were capable of degrading frog pars intermedia MSH as well as synthetic alpha-MSH. These results provide evidence that the frog hypophysis--pars intermedia and pars distalis--contains an alpha-MSH-like peptide.

Animals↗
PubMed1996

RAPD marker estimation of genetic structure among isolated northern leopard frog populations in the south-western USA.

Amphibians in the south-western United States are currently experiencing population declines. Causal explanations for these population changes as well as the implementation of sound management practices requires an understanding of the genetic structure of natural amphibian populations. To this end, we estimated genetic differences within and among seven isolated populations of northern leopard frogs, Rana pipiens, from Arizona and southern Utah using random amplified polymorphic DNA (RAPD) analyses. Fourteen arbitrarily designed primers detected 38 polymorphic loci in 85 individual frogs. Three types of population structure were observed in this study. (i) Two populations showed low genetic diversity (D = 0.10 and 0.04) and may have been established by relatively recent events. (ii) Two were not genetically distinct and exhibited a high degree of within-population diversity (D = 0.35). The possibility of gene flow between these populations is high due to their geographical proximity and their shared genetic structure. (iii) Three populations were genetically distinct from each other and the other populations, and exhibited intermediate within-population variation (D = 0.19, 0.17, 0.14). Genetic distances among the seven populations ranged from 0.00 to 0.20, suggesting that some of these leopard frog populations are genetically distinct. Although based on relatively small samples, these data suggest that leopard frog populations in the south-west are likely to represent unique genetic entities worthy of conservation. The management implications of these results are that isolated leopard frog populations should be evaluated on an individual basis to best preserve them.

Animals↗
PubMed1997

Anthelmintic treatment to eradicate cutaneous capillariasis in a colony of South African clawed frogs (Xenopus laevis).

The nematode Capillaria xenopodis (Pseudocapillaroides xenopi), a skin parasite of South African clawed frogs (Xenopus laevis), is quite common in laboratory animal facilities. It causes serious skin changes and may further lead to wasting and death of affected frogs. Various treatment protocols, using the anthelmintics ivermectin and levamisole, were successively tested for practicability of elimination of the parasite from a colony of clawed frogs. Nematodes were reduced below diagnostic levels by various methods of application of ivermectin (orally or by injection into the dorsal lymph sac, twice at intervals of 10 to 14 days). However, nematodes were found again in the treated animals 1 to 3 months later. Treatment by use of ivermectin-medicated tank water is not feasible due to its low water solubility. Elimination of the parasite was reliably achieved by use of levamisole-medicated tank water. Relapses were not seen during the 18-month posttreatment observation period. Levamisole concentration was 12 mg/L of water, with 4.17, 5.00, or 6.25 L of tank water/frog, and 50, 60, or 75 mg of levamisole available/frog, for at least 4 days, with treatments repeated after 10 to 14 days. Results were reproducible in two trials each with five tanks containing, in turn, four or five frogs each. A treatment trial carried out with a group of 20 adult frogs exposed to 12 mg of levamisole/L of tank water, but with only 2.5 L of tank water/frog (i.e., only 30 mg of levamisole available/animal), was not effective in eradicating the parasites. Not only the drug concentration, but also the amount of drug available per animal seems to be of importance. In contrast to thiabendazole, which is often reported in literature as treatment for cutaneous capillariasis, negative side effects were not observed with use of levamisole.

Animals↗
PubMed1998

Freeze duration influences postfreeze survival in the frog Rana sylvatica.

Survival, cryoprotection, and the time course for recovery of vital functions were studied in autumn-collected juvenile wood frogs (Rana sylvatica) following freezing at -1.5 degrees C for various periods. Frogs readily tolerated freezing for 3 or 9 d, but only 50% survived a 28-d freezing trial. Generally, the postfreeze return of vital functions (vascular circulation, pulmonary breathing, righting reflex, jumping reflex) occurred later in frogs frozen for longer periods. Augmenting endogenous levels of the cryoprotectant glucose (via injections) prior to freezing substantially increased freeze endurance, as these frogs had excellent survival after remaining frozen for as long as 49 d. The improved freeze endurance of glucose-loaded frogs apparently was not associated with a reduction in ice content but rather may reflect the greater availability of energy substrate needed to support metabolism of frozen ischemic tissues.

Animals↗
PubMed1998

The life history and host specificity of Hepatozoon clamatae (Apicomplexa: Adeleorina) and ITS-1 nucleotide sequence variation of Hepatozoon species of frogs and mosquitoes from Ontario.

The life cycle of an intraerythrocytic hemogregarine, Hepatozoon clamatae, was studied in green frogs (Rana clamitans melanota), bullfrogs (Rana catesbeiana), northern leopard frogs (Rana pipiens), and in the mosquito, Culex territans. Gametogenesis, fertilization, and sporogony occurred within cells of the Malpighian tubules of laboratory-reared Cx. territans that had fed on naturally infected frogs. Mature oocysts containing hundreds of sporocysts were observed in mosquitoes 30 days postfeeding. Each sporocyst enclosed 4 sporozoites. Merozoites appeared in the peripheral circulation of laboratory-reared bullfrogs, green frogs and leopard frogs that had been fed sporocysts 35-70 days previously. Attempts to infect American toads (Bufo americanus) and blue-spotted salamanders (Ambystoma laterale) were not successful. Gamonts of this parasite induced nuclear fragmentation or segmentation in host erythrocytes. The life cycle, morphological, and morphometric features of H. clamatae are compared with H. catesbianae, a similar species that also infects ranids. Nucleotide sequence analysis of the internal transcribed spacer region (ITS-1) of these sympatric species revealed that only 6 nucleotide sites of the 129 base pairs of this region were variable among 4 isolates of H. clamatae and 2 isolates of H. catesbianae. A redescription of H. clamatae is presented based on data from this study and from the original description by Stebbins in 1905.

Animals↗
PubMed1996

Urotensin II in the central nervous system of the frog Rana ridibunda: immunohistochemical localization and biochemical characterization.

Urotensin II (UII) is traditionally regarded as a product of the neurosecretory cells in the caudal portion of the spinal cord of jawed fishes. A peptide related to UII has been recently isolated from the frog brain, thereby providing the first evidence that UII is also present in the central nervous system of a tetrapod. In the present study, we have investigated the distribution of UII-immunoreactive elements in the brain and spinal cord of the frog Rana ridibunda by immunofluorescence using an antiserum directed against the conserved cyclic region of the peptide. Two distinct populations of UII-immunoreactive perikarya were visualized. The first group of positive neurons was found in the nucleus hypoglossus of the medulla oblongata, which controls two striated muscles of the tongue. The second population of immunoreactive cell bodies was represented by a subset of motoneurons that were particularly abundant in the caudal region of the cord (34% of the motoneuron population). The telencephalon, diencephalon, mesencephalon, and metencephalon were totally devoid of UII-containing cell bodies but displayed dense networks of UII-immunoreactive fibers, notably in the thalamus, the tectum, the tegmentum, and the granular layer of the cerebellum. In addition, a dense bundle of long varicose processes projecting rostrocaudally was observed coursing along the ventral surface of the brain from the midtelencephalon to the medulla oblongata. Reversed-phase high-performance liquid chromatography analysis of frog brain, medulla oblongata, and spinal cord extracts revealed that, in all three regions, UII-immunoreactive material eluted as a single peak which exhibited the same retention time as synthetic frog UII. Taken together, these data indicate that UII, in addition to its neuroendocrine functions in fish, is a potential regulatory peptide in the central nervous system of amphibians.

Animals↗
PubMed1996

Developmental regulation of the urea-cycle enzyme arginase in the direct developing frog Eleutherodactylus coqui.

Direct developing organisms obviate the larval intermediary from their ontogeny, hatching as miniature adults. To investigate this phenomenon, we have examined the developmental expression of arginase in the direct developing frog Eleutherodactylus coqui. An enzyme in the ornithine-urea cycle, the activation of liver arginase is necessary for the switch from ammonotelism to ureotelism which occurs when many frogs metamorphose and assume a terrestrial existence. Arginase enzyme activity is detectable at low levels in late prehatching stages of E. coqui, and increases at hatching, at which point the protein becomes detectable on Western blots. The activity increases gradually during posthatching development, reaching maximal levels at approximately the same time as yolk resorption is completed. Thyroid hormone is responsible for upregulating arginase activity during metamorphosis in Rana, but the role of thyroid hormone in direct developing frogs is unknown. A high dose (250 nM) of the thyroid hormone analogue 3,3'5-triiodo-L-thyronine (T3) caused precocious induction of arginase protein and activity, showing that even in a direct developing frog, some level of responsiveness to the metamorphic trigger, thyroid hormone, has been retained.

Animals↗
PubMed1999

Environmentally induced limb malformations in mink frogs (Rana septentrionalis).

In recent years, there has been an increase in the incidence of frog deformities throughout many of the northern states of North America. The most readily noticed malformations involve the hindlimbs of peri-metamorphic animals. We have analyzed skeletal preparations of metamorphosing mink frogs (Rana septentrionalis) collected from a site in Minnesota, in order to develop a better understanding of the possible causes. In this paper we describe the categories of abnormalities found at this site. The spectrum of deformities includes missing limbs, truncated limbs, extra limbs (including extra pelvic girdles), and skin webbings. We also describe a newly recognized malformation of the proximal-distal limb axis, a bony triangle. In this abnormality, the proximal and distal ends of the bone are adjacent to one another forming the base of a triangle. The shaft of the bone is bent double and protrudes laterally, the midpoint of the bone forming the apex of the triangle. In this paper we consider several recently proposed explanations for the recent outbreak of amphibian deformities. Based on our analysis, we conclude that the spectrum of abnormalities seen in these frogs is remarkably similar to the range of abnormalities that has been reported as a result of exposure of developing vertebrates to exogenous retinoids. Given the potential implications of this possibility for the welfare of humans as well as wildlife, further studies are needed to determine whether environmental retinoids are responsible for the frog deformities at the site we have examined.

Animals↗
PubMed1990

Characterization of different microenvironments at the surface of the frog's taste organ.

We used a panel of histochemical techniques to identify and characterize the cell-associated extracellular material at the surface of the frog's taste organ. We employed morphological and histochemical techniques using both the light microscope and the electron microscope. Results show that the apical, external aspect of cells reaching the surface of the taste organ is in close contact with a layer of amorphous material. The histochemical characteristics of this material vary according to the cell type with which it is in contact. Three different microenvironments can be identified at the surface of the frog's taste organ: type 1 microenvironment is associated with the superficial layer of mucus (secretory) cells; type 2 microenvironment characterizes the surface of the so-called wing cells, which reach the surface of the taste organ as thin laminae running among mucus cells; and type 3 microenvironment shrouds the free endings of putative taste cells and is rich in calcium and lipids. Type 2 and type 3 microenvironments fix peroxidase (a sapid macromolecule) with increasing affinity. We conclude that highly differentiated microenvironments exist at the surface of the frog's taste organ, and these could play a role in the chain of biological events leading to the taste sensation. Furthermore, characterization of the cell-associated, specific microenvironments can help clarify the role of the different cell types in the frog's taste organ.

Animals↗
PubMed2002

Morphology and projection pattern of medial and dorsal pallial neurons in the frog Discoglossus pictus and the salamander Plethodon jordani.

In the frog Discoglossus pictus and the salamander Plethodon jordani, the morphology and axonal projection pattern of neurons in the medial and dorsal pallium were determined by intracellular biocytin labeling. A total of 77 pallial neurons were labeled in the frog and 58 pallial neurons in the salamander. Within the medial pallium (MP) of the frog, four types of neurons were identified on the basis of differences in their axonal projection pattern. Type I neurons have bilateral projections into telencephalic and diencephalic areas; type II neurons have bilateral projections to telencephalic areas and ipsilaterally descending projections to diencephalic regions; type III neurons have only intratelencephalic connections, and a single type IV neuron has ipsilaterally descending projections. The somata of the four types occupy four nonoverlapping zones. Neurons of the dorsal pallium (DP) project exclusively to the ipsilateral MP and to the dorsal edge of the lateral pallium. In the ventral MP of the salamander, neurons have mostly intratelencephalic projections. Neurons in the dorsal MP project bilaterally to diencephalic and telencephalic regions. Neurons in the medial DP project ipsilaterally to the MP, lateral septum, nucleus accumbens, medial amygdala, and the internal granule layer of the olfactory bulb. In five cases, fibers were found in the commissura hippocampi, but in only two cases could these fibers be followed toward the contralateral MP and septum. Neurons in the lateral DP had no contralateral projections; they projected to the ipsilateral MP and in eight cases to the ipsilateral septum as well. Based on similarities of cytoarchitecture and projection pattern in neurons of the MP and DP, it is proposed that both frogs and salamanders have an MP subdivided into a ventral and dorsal portion, and a DP subdivided into a medial and a lateral portion.

Animals↗