| reinvestigation of the role of the optic vesicle in embryonic lens induction. | the induction of the lens by the optic vesicle in amphibians is often cited as support for the view that a single inductive event can lead to determination in a multipotent tissue. this conclusion is based on transplantation experiments whose results indicate that many regions of embryonic ectoderm which would normally form epidermis can form a lens if brought into contact with the optic vesicle. although additional evidence argues that during normal development other tissues, acting before the ... | 1988 | 3181032 |
| defining intermediate stages in cell determination: acquisition of a lens-forming bias in head ectoderm during lens determination. | cell determination in vertebrates requires integration of many events, although the mechanisms controlling the different stages in this process are poorly understood. while studies of lens determination have helped define some of these stages, we know very little about the intermediate steps involved in the commitment of ectoderm to lens formation. lens determination begins during gastrulation when ectoderm is briefly competent to respond to lens-inducing signals and progresses to a point, at th ... | 1997 | 9216064 |
| multiple antimicrobial peptides and peptides related to bradykinin and neuromedin n isolated from skin secretions of the pickerel frog, rana palustris. | the skin secretions of the north american pickerel frog rana palustris are toxic to both microorganisms and predators. a total of 22 peptides with differential growth-inhibitory activity towards bacteria and yeast were isolated from the electrostimulated secretions of r. palustris skin and were characterized structurally. thirteen of the antimicrobial peptides belong to five of the known families previously identified in the skins of other species of ranid frogs: brevinin-1 (3 peptides), esculen ... | 2000 | 11087945 |
| antimicrobial peptides and protease inhibitors in the skin secretions of the crawfish frog, rana areolata. | the dorsal skin of the crawfish frog, rana areolata, is associated with numerous prominent granular glands. proteomic analysis of electrically stimulated skin secretions from these glands enabled the identification and characterization of eight peptides with antimicrobial and hemolytic activity belonging to the previously identified brevinin-1, temporin-1, palustrin-2, palustrin-3, esculentin-1 (two peptides), and ranatuerin-2 (two peptides) families. the primary structures of the peptides were ... | 2002 | 12429503 |
| peptidomic analysis of the skin secretions of the pickerel frog rana palustris identifies six novel families of structurally-related peptides. | peptidomics methodology has been used to identify and characterize structurally 26 previously undescribed peptides in the electrically stimulated skin secretions of the north american pickerel frog rana palustris. peptides in the secretions were analyzed by electrospray mass spectrometry and components in mass range 700-2500 da, present in major abundance, were purified by reverse-phase hplc. cysteine-containing components were identified by treatment with dithiothreitol and 4-vinylpyridine and ... | 2003 | 12732335 |
| skin bradykinin-related peptides (brps) and their biosynthetic precursors (kininogens): comparisons between various taxa of chinese and north american ranid frogs. | bradykinins and related peptides (brps) occur in the defensive skin secretions of many amphibians. here we report the structures of brps and their corresponding biosynthetic precursor cdnas from the chinese brown frog, rana chensinensis, and the north american leopard frog, lithobates pipiens. r. chensinensis skin contained four transcripts each encoding a different kininogen whose organizations and spectrum of encoded brps were similar to those reported for the pickerel frog, lithobates palustr ... | 2008 | 18164514 |
| antimicrobial peptides from the skin secretions of the new world frogs lithobates capito and lithobates warszewitschii (ranidae). | taxonomic revisions within the anuran family ranidae have established the genus lithobates that currently comprises 49 species of frogs from the new world. peptidomic analysis, using reversed-phase hplc with on-line detection by electrospray mass spectrometry, has led to the identification of multiple antimicrobial peptides in norepinephrine-stimulated skin secretions of the north american frog lithobates capito and the central american frog lithobates warszewitschii. structural characterization ... | 2009 | 19635516 |
| anuran susceptibilities to ranaviruses: role of species identity, exposure route, and a novel virus isolate. | ranaviruses are responsible for widespread amphibian die-offs, particularly with larval anurans. to understand the factors that may be contributing to the emergence of ranaviruses, we conducted 3 experiments that exposed 3 species of larval anurans to either endemic frog virus 3 (fv3) or an fv3-like isolate from a ranaculture facility. our goals were to (1) determine the susceptibility of each species to each virus, (2) determine whether direct ingestion of virions or exposure to virions in a wa ... | 2010 | 20402227 |
| post-metamorphic change in activity metabolism of anurans in relation to life history. | newly-metamorphosed individuals of some species of frogs and toads differ from adults in behavior, ecology, and physiology. these differences may be related to broader patterns of the life histories of different species of frogs. in particular, the length of larval life and the size of a frog at metamorphosis appear to be significant factors in post-metamorphic ontogenetic change. these changes in performance are associated with rapid post-metamorphic increases in oxygen transport capacity. bufo ... | 1984 | 28312123 |
| balancing selection at a frog antimicrobial peptide locus: fluctuating immune effector alleles? | balancing selection is common on many defense genes, but it has rarely been reported for immune effector proteins such as antimicrobial peptides (amps). we describe genetic diversity at a brevinin-1 amp locus in three species of leopard frogs (rana pipiens, rana blairi, and rana palustris). several highly divergent allelic lineages are segregating at this locus. that this unusual pattern results from balancing selection is demonstrated by multiple lines of evidence, including a ratio of nonsynon ... | 2008 | 18799711 |
| the chinese bamboo leaf odorous frog (rana (odorrana) versabilis) and north american rana frogs share the same families of skin antimicrobial peptides. | the chinese bamboo leaf odorous frog (rana (odorrana) versabilis) and the north american pickerel frog (rana palustris) occupy different ecological niches on two different continents with no overlap in geographical distribution. r. palustris skin secretions contain a formidable array of antimicrobial peptides including homologs of brevinin-1, esculentin-1, esculentin-2, ranatuerin-2, a temporin and a family of peptides considered of unique structural attributes when isolated, palustrins 1-3. her ... | 2006 | 16621152 |
| intraspecific variation overrides origin effects in impacts of litter-derived secondary compounds on larval amphibians. | secondary compounds leached from plant litter can negatively affect aquatic amphibian larvae. non-native plants and their potentially distinct secondary compounds may constitute cryptic threats to native amphibians. we used the availability of both native and introduced phragmites australis (common reed) populations in north america to assess the importance of origin, intraspecific variation, and two purified classes of compounds (tannins and saponins; gradients 0-25 mg l(-1)) on two common and ... | 2013 | 23456242 |
| energetics of metamorphic climax in the pickerel frog (lithobates palustris). | anuran metamorphosis, the transition from aquatic larvae to terrestrial juveniles, is accompanied by significant morphological, physiological, and behavioral changes. timing of metamorphosis and final size, which can influence adult fitness, may depend on sufficient energy accumulated during the larval period to support metamorphosis. however, only two species of anurans have been examined for energetic costs of metamorphosis, rana tigrina and anaxyrus terrestris. based on these species, it has ... | 2009 | 19508896 |
| ichthyophonus-like infection in wild amphibians from québec, canada. | myositis associated with infection by ichthyophonus-like organisms was diagnosed in 35 of 260 (13%) wild amphibians collected in quebec, canada, from 1959 to 1964 (n = 30), and 1992 to 1999 (n = 230). infection was diagnosed in 17 green frogs rana clamitans, 9 wood frogs r. sylvatica, 4 red-spotted newts notophthalmus viridescens, 3 bullfrogs r. catesbeiana, 1 spring peeper pseudacris crucifer, and 1 pickerel frog r. palustris. the spring peeper and one of the bullfrogs were collected in 1964 fr ... | 2000 | 10843557 |
| the origin of fat from protein in the so-called fatty metamorphosis of phosphorus poisoning. | 588.780 grm. of frogs, all of the same sex, of the same comparative approximate weights, taken from the ground about the same time, kept awake and without food for nearly the same time, were divided into equal groups; the one group was poisoned with phosphorus, the other group held as a control. the frogs in the poisoned group lost in dried residue 8.821 grm. or 16.5 per cent of the dried residue of the control group; 1.182 grm. of nitrogen, corresponding to 7.388 of proteid, or 18.45 per cent o ... | 1899 | 19866916 |
| effects of lead-contaminated surface water from a trap and skeet range on frog hatching and development. | pickerel frogs (rana palustris) and bullfrogs (rana catesbeiana) were exposed from the egg stage to lead-contaminated surface water from a trap and skeet range. seven experimental treatments were employed: 25, 50, 75 and 100% range water, 100% range water plus a chelating agent (sodium citrate), control water and control water plus chelating agent. total lead concentrations in 100% range water treatments varied from 840-3150 microg litre(-1), with the filterable form accounting for approximately ... | 1997 | 15093433 |
| failure of tetracycline as a biomarker in batch-marking juvenile frogs. | recent widespread amphibian declines call for better techniques to assess population dynamics. tetracycline as a biomarker in capture-recapture studies is one technique used successfully in fish, reptiles, and mammals. a two-phase experimental study was conducted to evaluate tetracycline as a biomarker in green frogs (rana clamitans) and pickerel frogs (rana palustris). in the first experimental phase tadpoles were exposed to water containing either 250 mg/l or 500 mg/l tetracycline for a period ... | 2001 | 11310883 |
| competence tests of early amphibian gastrula tissue containing nuclei of one species (rana palustris) and cytoplasm of another (rana pipiens). | | 1973 | 4541557 |
| expression of paternal genes during embryogenesis in the viable interspecific hybrid amphibian embryo rana pipiens female x rana palustris male. electrophoretic analysis of five enzyme systems. | | 1971 | 5315654 |
| geographic variation of the lactate dehydrogenases of rana pipiens and rana palustris. | | 1969 | 5770236 |
| nucleocytoplasmic hybrids between rana pipiens and rana palustris. i. analysis of the developmental properties of the nuclei by means of nuclear transplantation. | | 1965 | 14332573 |
| hybridization between rana palustris and different geographical forms of rana pipiens. | | 1946 | 16578205 |
| moderate echinostoma trivolvis infection has no effects on physiology and fitness-related traits of larval pickerel frogs (rana palustris). | high intensity infections of echinostoma trivolvis metacercariae decrease survival and growth of young amphibian larvae. however, in nature, parasites are highly aggregated, which results in a large proportion of the amphibian population being only moderately infected. survival and growth responses at these more-common, low-infection levels remain poorly studied. thus, we investigated the effects of moderate echinostoma trivolvis metacercariae infection (following exposure to 0, 10, 30, or 90 ce ... | 2009 | 20049985 |
| effects of malathion on embryonic development and latent susceptibility to trematode parasites in ranid tadpoles. | we investigated the effects of embryonic exposure to the widely used organophosphate malathion (15-600 micro/l) on the early development and latent susceptibility of pickerel frog (rana palustris) tadpoles to the trematode parasite echinostoma trivolvis. the latent effects of contaminant exposure are rarely examined but could have important implications for individual survival and population viability. malathion decreased hatching success by 6.5% and viability rates by 17% at 600 microg/l, which ... | 2008 | 18613741 |
| relative toxicity of malathion to trematode-infected and noninfected rana palustris tadpoles. | amphibian populations around the world are facing threats that include disease and pollution. although the effect of environmental contaminants on susceptibility to infection has been demonstrated for several amphibian species, to our knowledge, the opposite interaction, infection status affecting contaminant susceptibility, has not been studied. we conducted standard 48-h toxicity tests to compare susceptibility to malathion, a widely used organophosphate insecticide, of uninfected pickerel fro ... | 2009 | 18401565 |
| rapid identification of precursor cdnas encoding five structural classes of antimicrobial peptides from pickerel frog (rana palustris) skin secretion by single step "shotgun" cloning. | the skin secretion of the north american pickerel frog (rana palustris) has long been known to have pronounced noxious/toxic properties and to be highly effective in defence against predators and against other sympatric amphibians. as it consists largely of a complex mixture of peptides, it has been subjected to systematic peptidomic study but there has been little focus on molecular cloning of peptide-encoding cdnas and by deduction, the biosynthetic precursors that they encode. here, we demons ... | 2007 | 17698247 |
| the complex array of bradykinin-related peptides (brps) in the peptidome of pickerel frog (rana palustris) skin secretion is the product of transcriptional economy. | previous peptidomic analyses of the defensive skin secretion from the north american pickerel frog, rana palustris, have established the presence of canonical bradykinin and multiple bradykinin-related peptides (brps). as a consequence of the multiplicity of peptides identified and their diverse primary structures, it was speculated that they must represent the products of expression of multiple genes. here, we present unequivocal evidence that the majority of brps (11/13) identified in skin sec ... | 2007 | 17459523 |
| brevinin-1 and multiple insulin-releasing peptides in the skin of the frog rana palustris. | few studies have comprehensively examined amphibian granular gland secretions for novel insulinotropic peptides. this study involved isolation and characterisation of biologically active peptides from the skin secretions of rana palustris frogs. crude secretions obtained by mild electrical stimulation from the dorsal skin surface were purified by reversed-phase hplc on a semipreparative vydac c18 column, yielding 80 fractions. these fractions were assayed for insulin-releasing activity using glu ... | 2004 | 15128283 |
| structural analysis of 20 oligosaccharide-alditols released from the jelly coat of rana palustris eggs by reductive beta-elimination characterization of the polymerized sequence [gal(beta1, 3)galnac(alpha1-4)]n. | the eggs of amphibians are surrounded by three to eight layers of jelly coats. this extracellular matrix is mainly composed of hydrated mucin-type glycoproteins. these highly glycosylated molecules are synthesized by oviduct and play an important role in the fertilization process. recent structural analyses have shown the strict species-specificity of the o-linked oligosaccharides which constitute 60-70% of these oviducal mucins. consequently, these carbohydrate chains represent new phenotypic m ... | 1999 | 10491074 |
| experiments showing the role of migrating neural crest (mesectoderm) in the formation of head skeleton and loose connective tissue in rana palustris. | | 1929 | 28354182 |
| supernumerary leg in a male frog (rana palustris). | | 1886 | 17231638 |