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PubMed2006

Organ-specific patterns of P450arom gene isoforms are modulated by p,p'-DDE in adult male European common frog, Rana temporaria.

The organ-specific gene expression patterns of P450arom isoforms have been studied in European common frog, Rana temporaria after exposure to DDE, using real-time PCR. Four groups of frogs were subcutaneously injected with DDE at 0.01, 0.1, 1 and 10 mg/kg body weight and one group, serving as the control was injected with pure corn oil. Brain, kidney, testis and liver P450aromA and P450aromB gene expressions were evaluated at day 14 after exposure. P450aromB data show that 0.1 and 10 mg DDE/kg doses caused 76% and 63% (testis) and 79% and 80% reductions, respectively, of mRNA levels. Brain P450aromB mRNA decreased 10% and 34%, respectively, after exposure to 0.01 and 0.1 mg DDE/kg. Thereafter, a 185% and 177% induction response of brain P450aromB was observed in the groups treated with 1 and 10 mg DDE/kg, respectively. In the kidney, 0.01, 0.1, 1 and 10 mg DDE/kg induced a 516%, 178%, 466% and 247% induction of P450aronB mRNA, respectively. P450aromA expression was not quantified in any of the organs. The relative abundance of P450aromB gene expression in different organs is in the order: kidney > brain > liver > testis. The present data suggest potential detrimental effect of organochlorine pesticides (OCs) and their metabolites on the European frog steroidogenic pathways. Given the high persistency in the environment and continued use in developing countries coupled with the tendency for global atmospheric transport, OCs and their metabolites such as DDE will remain a focus of concern both for scientific and societal reasons.

Animals↗
PubMed2006

Loss of neurturin in frog--comparative genomics study of GDNF family ligand-receptor pairs.

Four different GDNF family ligand (GFL)-receptor (GFRalpha) binding pairs exist in mammals, and they all signal via the RET receptor tyrosine kinase. However, the evolution of these molecules is poorly understood. We identified orthologs of all four GFRalpha receptors and GRAL (GDNF Receptor Alpha-Like) in all vertebrate classes, and a predicted GFR-like protein in several invertebrates. In addition, Gas1 (growth arrest-specific 1), a distant member of the GFR-superfamily, is present in both vertebrates and invertebrates. Analysis of exon structures suggests a common origin of GFR-superfamily proteins and early divergence of Gas1 from the common ancestor. Bony fishes have orthologs of all four mammalian GFLs, consistent with genome duplications in early vertebrates. Surprisingly, the clawed frog and chicken have only three GFLs: synteny analysis indicates loss of neurturin in frog and of persephin in chicken. Evolutionary trace analysis and protein structure homology modeling points at GDNF as the endogenous ligand of frog GFRalpha2.

Amino Acid Sequence↗
PubMed2006

Developmental and cell type-specific regulation of core promoter transcription factors in germ cells of frogs and mice.

This article reports on the comparative cell type-specific expression profiles of selected core promoter-associated transcription factors during gametogenesis and embryogenesis in frogs and mice. In frogs we tested TBP, TRF2/TLF, TRF3, TFIIAalphabeta, and ALF, as well as variant forms of TAFs 4, 5, and 6. Four of these factors, TRF3, TAF4L, TAF5L, and the previously-characterized ALF gene, are preferentially expressed in testis and ovary. In mice we tested TBP, TRF2/TLF, TRF3, TFIIAalphabeta, and ALF. The results showed that while ALF was present in testis and ovary, as expected, TRF3 could only be detected in the ovary. RT-PCR experiments using RNAs from microdissected ovary tissue, together with in situ hybridization analysis, showed that TRF3 and ALF genes are specifically expressed in oocytes in both adult and prepubertal animals, whereas, their somatic counterparts, TBP and TFIIAalphabeta, are present in oocytes and in surrounding somatic cells of the follicle. Furthermore, both mice and frogs displayed a reduction in TRF3 and ALF transcript levels around the time of fertilization. In mice, transcripts from these genes could again be detected at low levels in embryonic reproductive tissues, but only reached maximal levels in adult animals. Finally, the results of protein-DNA interaction assays show that all combinations of core promoter complexes can be formed in vitro using recombinant TBP, TRF3, TFIIA, and ALF, including a TRF3-ALF complex. Overall, the diverse gene regulatory patterns observed here and in earlier reports indicate precise control over which transcription factor complexes can be formed in vivo during gametogenesis and early embryogenesis.

Animals↗
PubMed2005

Serotonin metabolism in directly developing frog embryos during paternal care.

Central serotonin (5-HT) metabolism during embryogenesis and a 3-day post-hatching period was analyzed using high performance liquid chromatography in the directly developing frog, Eleutherodactylus coqui. This anuran bypasses the free-swimming larval stage and embryos hatch as miniature frogs in the adult phenotype. During embryogenesis and for a short time immediately after hatching, male E. coqui provide paternal care by brooding and guarding eggs/embryos to prevent desiccation and predation. Serotonin and its catabolite, 5-HIAA, were measured from whole brain during embryogenesis and at 3 days post-hatch to identify critical periods in 5-HT development and to determine the relationship between 5-HT and life history events such as hatching and frog dispersal from the nest site. Serotonergic activity was highest during the early-mid embryonic stages as indicated by the ratio of 5-HIAA/5-HT, a general indicator of turnover and metabolism. There were significant increases in tissue concentrations of 5-HT during the latest or terminal embryonic stage, just prior to hatching, and also at 3 days post-hatch, shortly before neonates disperse into the rainforest. These two increases probably represent different functional requirements during development. The first may occur as a result of the surge of development in the 5-HT system during late embryogenesis that occurs in E. coqui and the second may be from the increase demand in sensory and motor neural development required before dispersal from the nest site.

Animals↗
PubMed2004

Dual effect of GABA on descending monosynaptic excitatory postsynaptic potential in frog lumbar motoneurons.

Monosynaptic excitatory postsynaptic potentials (EPSPs) evoked by stimulating ipsilateral ventrolateral column (VLC) in the thoracic section were recorded in lumbar motoneurons within the isolated spinal cord of the frog Rana ridibunda. Bath application of the selective GABAB receptor agonist (-)-baclofen (0.05 mM) caused a reduction in the peak amplitude of VLC EPSP. Baclofen did not cause any consistent change in the membrane potential or in the EPSP waveform within frog motoneurones. The selective GABA(B) receptor antagonist saclofen (0.1 mM) completely blocked the effect of (-)-baclofen on VLC EPSP. A decrease in VLC EPSP peak amplitude was also observed during GABA (0.5 mM) application. Unlike (-)-baclofen, inhibition of VLC EPSP induced by GABA was accompanied by a shortening of the EPSP time course and a reduction in membrane input resistance within lumbar motoneurons. The decrease in VLC EPSP peak amplitude induced by (-)-baclofen and GABA was accompanied by an increase in the paired-pulse facilitation. These data provide evidence for a dual pre- and postsynaptic GABAergic inhibition of the VLC monosynaptic EPSP in lumbar motoneurons within the frog spinal cord.

Animals↗
PubMed2005

A family of acyclic brevinin-1 peptides from the skin of the Ryukyu brown frog Rana okinavana.

The 24 amino-acid residue antimicrobial peptide, brevinin-1 is synthesized in the skins of a wide range of species of Eurasian and North American frogs belonging to the genus Rana. All previously characterized brevinin-1 peptides contain the cyclic heptapeptide domain Cys18-(Xaa)4-Lys-Cys24 at the COOH-terminus of the molecule. Four structurally related peptides were isolated from an extract of the skin of the Ryukyu brown frog Rana okinavana. The amino acid sequences of the peptides [Phe-(Xaa)4-Ile-(Xaa)2-Leu-Ala-Lys-Gly-Leu-Pro-Ser-Leu-Ile-Xaa-Leu-Xaa-Lys-Lys.NH2] identified them as members of the brevinin-1 family that lacked the COOH-terminal cyclic domain but contained a C-terminally alpha-amidated residue. It is suggested, as one possibility, that the Cys18 in the brevinin-1 consensus sequence has been deleted and the Cys24 residue has mutated to a glycine that acts as substrate for peptidyl-glycine alpha-amidating monooxygenase. The peptides potently inhibited the growth of Escherichia coli and Staphylococcus aureus confirming that a cyclic domain is not necessary for antimicrobial activity. A fifth peptide (SFLNFFKGAA10KNLLAAGLDK20LKCKISGTQC30), that also displayed broad-spectrum antimicrobial activity, was isolated from the skin extract and showed structural similarity with members of the ranatuerin-2 family previously isolated from the skin of North American ranid frogs.

Amino Acid Sequence↗
PubMed2005

Amphibian skin peptides and their corresponding cDNAs from single lyophilized secretion samples: identification of novel brevinins from three species of Chinese frogs.

Brevinins are peptides of 24 amino acid residues, originally isolated from the skin of the Oriental frog, Rana brevipoda porsa, by nature of their microbicidal activity against a wide range of Gram-positive and Gram-negative bacteria and against strains of pathogenic fungi. cDNA libraries were constructed from lyophilized skin secretion of three, unstudied species of Chinese frog, Odorrana schmackeri, Odorrana versabilis and Pelophylax plancyi fukienensis, using our recently developed technique. In this report, we describe the "shotgun" cloning of novel brevinins by means of 3'-RACE, using a "universal" degenerate primer directed towards a highly conserved nucleic acid sequence domain within the 5'-untranslated region of previously characterized frog skin peptide cDNAs. Novel brevinins, deduced from cloned cDNA open-reading frames, were subsequently identified as mature peptides in the same samples of respective species skin secretions. Bioinformatic analysis of both prepro-brevinin nucleic acid sequences and translated open-reading frame amino acid sequences revealed a highly conserved signal peptide domain and a hypervariable anti-microbial peptide-encoding domain. The experimental approach described here can thus rapidly provide robust structural data on skin anti-microbial peptides without harming the donor amphibians.

Amino Acid Sequence↗
PubMed2006

Antimicrobial peptides from diverse families isolated from the skin of the Asian frog, Rana grahami.

Seven peptides with antimicrobial activity were isolated in pure form from an extract of the skin of the Yunnanfu Kunming frog Rana grahami Boulenger, 1917. The peptides were identified as belonging to the nigrocin-2 (three peptides), brevinin-1 (one peptide), brevinin-2 (three peptides), and esculentin-1 (one peptide) families. Nigrocin-2GRb (GLFGKILGVGKKVLCGLSGMC) containing three lysine residues, represented the peptide with highest potency against microorganisms (MIC = 3 microM against Escherichia coli, 12.5 microM against Staphylococcus aureus and 50 microM against Candida albicans) and the greatest hemolytic activity against human erythrocytes (LD50 = 40 microM). In contrast, nigrocin-2GRa (GLLSGILGAGKHIVCGLSGLC) and nigrocin-2GRc (GLLSGILGAGKNIVCGLSGLC), with only a single lysine residue, showed weak antimicrobial and hemolytic activity. Phylogenetic relationships among Eurasian ranid frogs are less well understood than those of North American ranids but the primary structures of the R. grahami antimicrobial peptides suggest a close relationship of this species with the Japanese pond frogs R. nigromaculata and R. porosa brevipoda.

Amino Acid Sequence↗
PubMed2006

Lividins: novel antimicrobial peptide homologs from the skin secretion of the Chinese Large Odorous frog, Rana (Odorrana) livida. Identification by "shotgun" cDNA cloning and sequence analysis.

Odorous frogs of the sub-genus Odorrana are of oriental distribution, and are so called due to the foul smell of their defensive skin secretions released from specialized skin glands following stress or predator attack. Here we report the application of a "shotgun" skin secretion cDNA library cloning technique which can rapidly expedite identification of secretion bioactive peptides. From a library constructed from the skin secretion of the Large Chinese Odorous frog, Rana (Odorrana) livida, we have identified four novel peptides whose primary structures were deduced initially from cloned precursors. Subsequently, mature peptides were located in and structurally characterized from reverse phase HPLC fractions of skin secretion. Named lividins 1-4, these were found to be structural homologs of known antimicrobial peptide families from Rana frogs. Rapid identification of novel peptides can thus be rapidly achieved using this non-invasive, non-destructive technology and the extensive similarities revealed between antimicrobial peptide precursor organization and nucleic acid sequences would lend support to the hypothesis that they have a common ancestral origin.

Amino Acid Sequence↗
PubMed2006

Expression of genes encoding antimicrobial and bradykinin-related peptides in skin of the stream brown frog Rana sakuraii.

Peptidomic analysis of an extract of the skin of the stream brown frog Rana sakuraii Matsui and Matsui, 1990 led to the isolation of a C-terminally alpha-amidated peptide (VR-23; VIGSILGALASGLPTLISWIKNR x NH2) with broad-spectrum antimicrobial activity that shows structural similarity to the bee venom peptide, melittin together with two peptides belonging to the temporin family (temporin-1SKa; FLPVILPVIGKLLNGIL x NH2 and temporin-1SKb; FLPVILPVIGKLLSGIL x NH2), and peptides whose primary structures identified them as belonging to the brevinin-2 (2 peptides) and ranatuerin-2 (1 peptide) families. Using a forward primer that was designed from a conserved region of the 5'-untranslated regions of Rana temporaria preprotemporins in a 3'-RACE procedure, a cDNA clone encoding preprotemporin-1SKa was prepared from R. sakuraii skin total RNA. Further preprotemporin cDNAs encoding temporin-1SKc (AVDLAKIANIAN KVLSSL F x NH2) and temporin-1SKd (FLPMLAKLLSGFL x NH2) were obtained by RT-PCR. Unexpectedly, the 3'-RACE procedure using the same primer led to amplification of a cDNA encoding a preprobradykinin whose signal peptide region was identical to that of preprotemporin-1SKa except for the substitution Ser18-->Asn. R. sakuraii bradykinin ([Arg0,Leu1,Thr6,Trp8] BK) was 28-fold less potent than mammalian BK in effecting B2 receptor-mediated relaxation of mouse trachea and the des[Arg0] derivative was only a weak partial agonist. The evolutionary history of the Japanese brown frogs is incompletely understood but a comparison of the primary structures of the R. sakuraii dermal peptides with those of Tago's brown frog Rana tagoi provides evidence for a close phylogenetic relationship between these species.

5' Untranslated Regions↗
PubMed2004

Basic organization principles of the VOR: lessons from frogs.

Locomotion is associated with a number of optical consequences that degrade visual information processing in the absence of appropriate compensatory movements. The resulting retinal image flow is counteracted by coordinated eye-head reflexes that are initiated by optokinetic and vestibular inputs. The contribution of the vestibulo-ocular reflex (VOR) for stabilizing retinal images is relatively small in amplitude in frogs but important in function by compensating for the non-linearities of the neck motor system. The spatial tuning of the VOR networks underlying the angular (AVOR) and linear (LVOR) with respect to canal and extraocular motor coordinates is organized in a common, canal-related reference frame. Thereby, the axes of head and eye rotation are aligned, principle and auxiliary VOR connections transform vestibular into motor signals and parallel AVOR and LVOR circuits mediate vergence and version signals separately. Comparison of these results with data from other vertebrates demonstrates a number of fundamental organization principles common to most vertebrates. However, the fewer degrees of behavioral freedom of frogs are reflected by the absence of, e.g. a functioning velocity storage network or of a fixation suppression of the VOR. In vitro experiments with the isolated brainstem and branches of N.VIII attached were used to study the putative transmitters of vestibular nerve afferent inputs, the postsynaptic receptor subtypes of second-order vestibular neurons and their dynamic response properties. Evidence is presented that suggests that afferent vestibular nerve fibers with different dynamic response properties activate different subtypes of glutamate receptors. The convergence pattern of monosynaptic afferent nerve inputs from different labyrinthine organs onto second-order vestibular neurons is remarkably specific. As a rule, second-order vestibular neurons receive converging afferent nerve inputs from one semicircular canal and from a specific sector of hair cells on one otolith organ. This convergence pattern remains malleable even in adulthood and reorganization is initiated by activity-related changes in vestibular nerve afferent fibers. The output of second-order vestibular neurons is modified by at least three inhibitory control loops. Uncrossed inhibitory vestibular side loops appear to control specifically the dynamic response tuning, whereas coplanar commissural inhibitory inputs improve mainly the spatial tuning and the cerebellar feedback loop controls the response gain. Among the targets of second-order vestibular projection neurons are extraocular motoneurons and internuclear neurons. Extraocular motoneurons differ among each other by the presence of very different response dynamics. These differences may represent a co-adaptation to the response dynamics of twitch and non-twitch extraocular muscle fibers. Different dynamical properties are required for a rapid acceleration of the globe at the one end and for the maintenance of a stable eccentric eye position over long periods of time at the other end of a continuum of variations in dynamic response properties. The maintenance of a given eccentric eye position over long periods of time is especially well developed in frogs and assists visual surveillance during lurking in the absence of saccades.

Animals↗
PubMed2005

An antimicrobial peptide from the skin secretions of the mountain chicken frog Leptodactylus fallax (Anura:Leptodactylidae).

A 25 amino-acid-residue, C-terminally alpha-amidated peptide with antimicrobial activity, which has been termed fallaxin, was isolated in high yield from the norepinephrine-stimulated skin secretions of the mountain chicken frog Leptodactylus fallax (Anura:Leptodactylidae). The amino acid sequence of the peptide (Gly-Val-Val-Asp-Ile-Leu-Lys-Gly-Ala-Ala-Lys-Asp-Ile-Ala-Gly-His-Leu-Ala-Ser-Lys-Val-Met-Asn-Lys-Leu.NH2) shows structural similarity with members of the ranatuerin-2 family previously isolated from the skins of frogs of the genus Rana that are only distantly related to the Leptodactylidae. This observation is consistent with the hypothesis that many frog skin antimicrobial peptides are related evolutionarily, having arisen from multiple duplications of an ancestral gene that existed before the radiation of the different families. Fallaxin inhibited the growth of reference strains of Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella pneumoniae) but with relatively low potency (MIC> or =20 microM) and was inactive against the Gram-positive bacterium (Staphylococcus aureus) and the yeast Candida albicans. The hemolytic activity of fallaxin was very low (HC50>200 microM). A second peptide, comprising residues (1-22) of fallaxin, was also isolated from the skin secretions but this component was inactive against the microorganisms tested.

Amino Acid Sequence↗
PubMed2006

Assessing the effects of three dental impression materials on the isolated sciatic nerve of rat and frog.

The effects on nerve tissue of three dental impression pastes were compared in this study. Two of the impression pastes, Examix and Express 3M, contained vinyl polysiloxane while the other, Xanthopren, did not. An in vitro model based on the isolated sciatic nerve of the frog and rat was used. As an indication of the proper functioning of the fibres in the nerve, the amplitude of evoked compound action potential (CAP) was monitored continuously. The results clearly showed that the number of active nerve fibres in the isolated sciatic nerves of either rat or frog exposed directly to impression pastes containing vinyl polysiloxane, decreased much faster than those of the nerves in contact to impression material without vinyl polysiloxane. When the nerve of the frog was exposed to Xanthopren there was a decrease in the CAP to 50% of the control values within 56.87+/-2.42 h (n=6). This value was called inhibition time to 50%, IT(50) and for Examix it was found to be 9.97+/-1.53 h. When the nerve of the rat was exposed to Xanthopren, the IT(50) was 15.34+/-2.97 h (n=6) for the Xanthopren and only 2.86+/-1.20 h for Examix and 2.76+/-0.48 h for Express 3M (n=6). There was no significant difference between the action of the last two compounds (P=0.85). This fast nerve fibre inactivation could be caused either by the chemical used for the synthesis of the two impression pastes, Examix and Express 3M, or by the unusual constriction of the nerve when it is embedded in the materials with vinyl polysiloxane. There is strong evidence to support the first case, since the incubation of the nerve in the presence of Examix, Express 3M and Xantopren in a way so the nerve was not in contact with the impression pastes, shows a much faster decrease of the CAP in the presence of the first two pastes. The decrease is caused by the death of nerve fibres, since there is no recovery in the CAP after the removal of Examix from the incubating saline.

Action Potentials↗
PubMed2004

Main alkaloids from the Brazilian dendrobatidae frog Epipedobates flavopictus: pumiliotoxin 251D, histrionicotoxin and decahydroquinolines.

Epipedobates flavopictus, Dendrobatidae, is a small aposematic frog found in Brazilian Cerrado bioma. In the present work, we isolated and characterized chemically the most abundant alkaloids present in the cutaneous extract of E. flavopictus. The specimens were collected in Pirenópolis (Goiás, Brazil), their skins were removed and extracted with methanol, and submitted to purification by HPLC and identification by gas chromatography and mass spectrometry. Pumiliotoxin 251D, histrionicotoxin 285Da and two decahydroquinolines, 219A and 243A, were identified. The pumiliotoxin 251D was tested on isolated frog sciatic nerve and on isolated guinea pig ileum muscle. The pumiliotoxin 251D slightly reduced the action potentials amplitude of frog sciatic nerve. The crude skin extract of E. flavopictus and the pumiliotoxin 251D produced rhythmic contractions and increased the muscular tension on isolated guinea pig ileum.

Alkaloids↗
PubMed2005

Plasma sex steroid and thyroid hormones profile in male water frogs of the Rana esculenta complex from agricultural and pristine areas.

Some chemical compounds used in intensive agriculture have been found to induce estrogenic effects; therefore a histological analysis of the testes and an evaluation of plasma levels of sex steroid, thyroid hormones, and vitellogenin were carried out in adult male water frogs of two coexisting taxa (Rana lessonae and the hemiclonal hybrid Rana esculenta) sampled in agricultural and pristine areas. Differences in seasonal profiles of hormones were found in water frogs living in the agricultural area where the presence of endocrine disrupting compounds was suspected on the basis of a previous study. In R. esculenta, sampled in the pristine area, high androgen levels were found in May; the opposite trend was found for R. esculenta sampled in agricultural areas in which the highest androgen levels were found in September, significantly lower compared with those found in R. esculenta sampled in the pristine area. Low androgen levels were also recorded in R. lessonae males sampled both in pristine and agricultural areas, while the highest levels were found in September. Regarding the trend of estradiol-17beta, an increase of this hormone was found in July both in esculenta and lessonae sampled in the agricultural area, and in the same month an estradiol-17beta peak, even though lower, was also found both in esculenta and lessonae males captured in the pristine area; detectable vitellogenin was found neither in males captured in the agricultural area, nor in those sampled in the pristine one. Moreover, while no significant changes of thyroid hormones were found either in the esculenta or lessonae males sampled in the pristine area, increased T3 and T4 titers were found in July in both esculenta and lessonae captured in the agricultural area. Morphological differences of the testes in males of parental species captured in the agricultural area were also observed. These findings indicate alterations in endocrine and reproductive function in frogs in the agricultural area, that could suggest the presence of endocrine disrupting compounds.

Agriculture↗
PubMed2005

Bradykinin-related peptides and tryptophyllins in the skin secretions of the most primitive extant frog, Ascaphus truei.

The tailed frog Ascaphus truei occupies a unique position in phylogeny as the most primitive extant anuran and is regarded as the sister taxon to the clade of all other living frogs. A previous study led to the isolation of eight antimicrobial peptides, termed ascaphins, from norepinephrine-stimulated skin secretions. Peptidomic analysis (HPLC separation followed by MALDI mass spectrometry and Edman degradation) of these secretions has led to the identification and structural characterization of 13 additional peptides present in relatively high concentration. In addition to bradykinin (BK; RPPGFSPFR), a C-terminally extended bradykinin (peptide RD-11; RPPGFSPFRVD), a bradykinin-like peptide (peptide AR-10; APVPGLSPFR), and a C-terminally extended form of this peptide (peptide AV-12; APVPGLSPFRVV) were obtained in pure form. These peptides produced concentration-dependent relaxation of precontracted mouse tracheal rings with a rank order of potency of BK>RD-11>AR-10>AV-12 but only RD-11 caused the same maximal relaxation as bradykinin. Four small peptides were also isolated from the skin secretions that contain the Pro-Trp motif that is a characteristic of the tryptophyllin family of peptides previously identified in skins of frogs of the family Hylidae. The data show that the synthesis of dermal peptides that may play a role in defense against predators arose early in the evolution of anurans.

Animals↗
PubMed2004

Phylogeny of the New World true frogs (Rana).

Phylogenetic relationships among the species of true frogs (Rana) from North, South, and Central America were investigated based on the sequences of approximately 2 kb from the mitochondrial genome, sampled from most of the described species, as well as eight undescribed species. This analysis, combined with previous studies of the phylogeny of New World Rana, served as the basis for a revised classification of the group. The American species of Rana are not monophyletic; the western North American Amerana is more closely related to the R. temporaria group of Eurasia (together, these frogs form the group Laurasiarana). The remaining species from the Americas form the monophyletic group Novirana, which includes: R. sylvatica; Aquarana (the R. catesbeiana group); Ranula (the R. palmipes group, including the mostly upland Levirana species and the mostly lowland Lithobates species); Torrentirana (the R. tarahumarae group, or Zweifelia, plus R. sierramadrensis), Stertirana (the R. montezumae group, or Lacusirana, plus R. pipiens), Nenirana (the R. areolata group), and Scurrilirana (most of the southern and tropical leopard frogs). The mitochondrial sequences supported many of the previous hypotheses of relationships of New World Rana, although there were some differences involving the placement of the species R. pipiens, R. sierramadrensis, and R. sylvatica. Parametric bootstrap analyses indicated significant support for the relationships inferred from the mtDNA sequences, and rejected the previous hypotheses of relationships for these three species.

Americas↗
PubMed2002

Antimicrobial peptide defenses of the Tarahumara frog, Rana tarahumarae.

Populations of the Tarahumara frog Rana tarahumarae have decreased markedly in recent years in the northern part of their range. Infection by the chytrid fungus Batrachochytrium dendrobatidis has been implicated in these declines. To determine whether antimicrobial peptides in the skin provide protection against this pathogen, norepinephrine-stimulated skin secretions were tested for their ability to inhibit growth of B. dendrobatidis in vitro. After concentration, crude mixtures of skin peptides inhibited the growth of the chytrid in a concentration-dependent manner. Proteomic analysis led to the identification and characterization of three peptides belonging to the brevinin-1 family of antimicrobial peptides and three belonging to the ranatuerin-2 family. The two most abundant peptides, ranatuerin-2TRa (GIMDSIKGAAKEIAGHLLDNLKCKITGC) and brevinin-1TRa (FLPVIAGIAANVLPKLFCKLTKRC), were active against B. dendrobatidis (MIC of 50 microM for ranatuerin-2TRa and 12.5 microM for brevinin-1TRa against zoospores). These data clearly show that antimicrobial peptides in the skin secretions of the Tarahumara frog are active against B. dendrobatidis and should provide some protection against infection. Therefore, the observed susceptibility of these frogs to this pathogen in the wild may be due to the effects of additional environmental factors that impair this innate defense mechanism, leading to the observed population declines.

Amino Acid Sequence↗