Статті в журналах: "Frogs Development"

1

Tokita, Masayoshi, and Noriko Iwai. "Development of the pseudothumb in frogs." Biology Letters 6, no. 4 (February 10, 2010): 517–20. http://dx.doi.org/10.1098/rsbl.2009.1038.

Повний текст джерела

Анотація:

Frogs have highly conserved hand and foot morphology, possessing four fingers and five toes. As an exception, two Japanese ranid frog species, the Otton frog Babina subaspera and the dagger frog Babina holsti , possess a unique thumb-like structure (the pseudothumb) in the forelimb, giving an appearance of a total of five fingers on the hand. To obtain insights into the developmental mechanisms that generate this novel character, we investigated the hand morphogenesis of the Otton frog. The unique morphological pattern of the pseudothumb was already established in juveniles. Surprisingly, the bud-like structure, which is similar to the area of inductive activity (e.g. feather buds in birds and the carapacial ridge in turtles), was detected over the site where the future prepollex develops in larvae. By contrast, this bud-like structure was not found in larvae of other ranid species. We discuss possible scenarios that would favour the evolution of this very unusual trait in frogs.

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Gardiner, David, A. Ndayibagira, Felix Grün, and Bruce Blumberg. "Deformed frogs and environmental retinoids." Pure and Applied Chemistry 75, no. 11-12 (January 1, 2003): 2263–73. http://dx.doi.org/10.1351/pac200375112263.

Повний текст джерела

Анотація:

Since the early 1990s, a substantial number of deformed frogs have been observed in North America, particularly in the upper Midwest and Canada. Attempts to understand the etiology of the deformed frog problem have met with limited success to date with nearly as many proposed explanations as research groups working on the problem. Models for the mechanism underlying the development of deformed frogs include parasite/predation, ultraviolet radiation, and chemical exposure. Each model has its strengths and weaknesses. Despite contentious debate among researchers, there is an overall consensus that the increasing prevalence of deformed frogs is the result of a water-borne contaminant that has recently appeared, or reached a critical concentration. Our detailed analysis of malformed frogs collected in Minnesota ponds and lakes suggested that limb patterning was being modified by the disruption of a retinoid-sensitive developmental signaling pathway. Accordingly, we focused in the identification and characterization of bioactive retinoids from lake water and showed that retinoid treatment of frog embryos at sensitive times of development could recapitulate the full spectrum of limb abnormalities observed in field specimens in the laboratory. These data have led to the conclusion that inappropriate modulation of retinoid signaling by environmental contaminants is the mechanism underlying the increased incidence of frog malformations.

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Russell, Devlin. "Intention as action under development: why intention is not a mental state." Canadian Journal of Philosophy 48, no. 5 (2018): 742–61. http://dx.doi.org/10.1080/00455091.2017.1414524.

Повний текст джерела

Анотація:

AbstractThis paper constructs a theory according to which an intention is not a mental state but an action at a certain developmental stage. I model intention on organic life, and thus intention stands to action as (e.g.) tadpole stands to frog. I then argue for this theory by showing how it overcomes three problems: intending while (1) merely preparing, (2) not taking any steps, and (3) the action is impossible. The problems vanish when we see that not all actions are mature. Just as some frogs (such as tadpoles) are immature frogs, some actions (such as intentions) are immature actions.

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Mello, Sílvia Conceição Reis Pereira, Roberto Rodrigues de Oliveira, Marcelo Maia Pereira, Eliane Rodrigues, Willian Nascimento Silva, and José Teixeira de Seixas Filho. "Development of a water recirculating system for bullfrog production: technological innovation for small farmers." Ciência e Agrotecnologia 40, no. 1 (February 2016): 67–75. http://dx.doi.org/10.1590/s1413-70542016000100006.

Повний текст джерела

Анотація:

ABSTRACT Despite the technological progress in frog farming, issues related to the environment, biosafety, and the use of technologies that minimise environmental impacts are frequently neglected by farmers. With the goal of developing a low-cost technology for reuse and preservation of water quality, an anaerobic filtering system combined with an aerobic filtering system was implemented in the grow-out sector in the Frog Culture Research Unit at Fundação Instituto de Pesca do Estado do Rio de Janeiro (FIPERJ). The filtering system received the effluent from six pens of frogs that were populated with 362 frogs in different development phases. The efficiency of the filtering system was evaluated by an analysis of the water before and after passing through the filters. In addition to the standards of water quality, the animals' performance was also observed through monitoring rates of survival, weight gain and feed conversion ratio. The results showed the effectiveness of the filtering system by removing organic matter, on average 87%. The values of total ammonia and non-ionisable reached 1.04 and 0.004 mg/L, respectively. Also, frogs subjected to the system presented satisfactory rates of weight gain and a high survival rate (97%).

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Chang, Yi-Chun, Shou-Hsien Li, Hsuan-You Lin, Szu-Lung Chen, and Ming-Hsung Chang. "Development of 22 polymorphic microsatellite markers for Taipei grass frogs (Hylarana taipehensis)." Amphibia-Reptilia 37, no. 1 (2016): 117–20. http://dx.doi.org/10.1163/15685381-00003027.

Повний текст джерела

Анотація:

The Taipei grass frog, Hylarana taipehensis, is a slender frog widely distributed throughout Southeast Asia and thus is predicted to contain a high level of genetic diversity and undetected endemics. Habitat destruction and pesticide pollution have resulted in the population crash of some genetically distinct populations. To assign appropriate conservation measures, a genetic survey covering individuals from the entire species’ range is urgently required to reveal cryptic diversity and delineate these frogs into various management units. However, effective codominant markers are lacking for this species. Here, we reported 22 tetranucleotide microsatellite loci for H. taipehensis. Alleles ranged between 6 and 17 per locus. The observed heterozygosities and expected heterozygosities were 0.280-0.893 and 0.721-0.908, respectively. These polymorphic microsatellites should be useful in identifying the most important units for conservation management of the Taipei grass frogs.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Tong, Qing, Xiao-peng Du, Zong-fu Hu, Li-yong Cui, and Hong-bin Wang. "Modelling the growth of the brown frog (Rana dybowskii)." PeerJ 6 (May 16, 2018): e4587. http://dx.doi.org/10.7717/peerj.4587.

Повний текст джерела

Анотація:

Well-controlled development leads to uniform body size and a better growth rate; therefore, the ability to determine the growth rate of frogs and their period of sexual maturity is essential for producing healthy, high-quality descendant frogs. To establish a working model that can best predict the growth performance of frogs, the present study examined the growth of one-year-old and two-year-old brown frogs (Rana dybowskii) from metamorphosis to hibernation (18 weeks) and out-hibernation to hibernation (20 weeks) under the same environmental conditions. Brown frog growth was studied and mathematically modelled using various nonlinear, linear, and polynomial functions. The model input values were statistically evaluated using parameters such as the Akaike’s information criterion. The body weight/size ratio (Kwl) and Fulton’s condition factor (K) were used to compare the weight and size of groups of frogs during the growth period. The results showed that the third- and fourth-order polynomial models provided the most consistent predictions of body weight for age 1 and age 2 brown frogs, respectively. Both the Gompertz and third-order polynomial models yielded similarly adequate results for the body size of age 1 brown frogs, while the Janoschek model produced a similarly adequate result for the body size of age 2 brown frogs. The Brody and Janoschek models yielded the highest and lowest estimates of asymptotic weight, respectively, for the body weights of all frogs. TheKwlvalue of all frogs increased from 0.40 to 3.18. TheKvalue of age 1 frogs decreased from 23.81 to 9.45 in the first four weeks. TheKvalue of age 2 frogs remained close to 10. Graphically, a sigmoidal trend was observed for body weight and body size with increasing age. The results of this study will be useful not only for amphibian research but also for frog farming management strategies and decisions.

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Narayan, Edward, Frank Molinia, Ketan Christi, Craig Morley, and John Cockrem. "Urinary corticosterone metabolite responses to capture, and annual patterns of urinary corticosterone in wild and captive endangered Fijian ground frogs (Platymantis vitiana)." Australian Journal of Zoology 58, no. 3 (2010): 189. http://dx.doi.org/10.1071/zo10010.

Повний текст джерела

Анотація:

This study was based on the development of a non-invasive glucocorticoid enzyme-immunoassay for the assessment of stress in wild and captive endangered Fijian ground frogs (Platymantis vitiana). Enzyme-immunoassays were developed and validated for the first time to non-invasively measure both cortisol and corticosterone metabolites in frog urine. Frog urine showed parallel displacement with corticosterone but not cortisol standards, therefore corticosterone enzyme immunoassays were used to examine stress in wild and captive frogs. Urinary corticosterone metabolite concentrations increased in frog urine (n = 4) at 6 h, 1 day and 2 days after injection with adrenocorticotropic hormone (0.44 μg g–1 bodyweight), indicating that the corticosterone enzyme-immunoassay could detect changes in circulating corticosterone in frogs. Urinary concentrations of corticosterone were measured in wild frogs (n = 18) after capture in the field. The first measurement beyond the initial sample was at 2–3 h. Mean urinary corticosterone concentrations rose after the initial sample and were significantly elevated in samples collected 3–4 h after capture. This is the first demonstration of a urinary corticosterone response to capture in amphibians. Urinary corticosterone metabolite concentrations for all months combined were lower in captive males than in wild males, and differed between vitellogenic, non-vitellogenic and captive females. Concentrations did not differ between captive and wild females. In conclusion, urinary corticosterone enzyme immunoassays can be used in frogs for assessing stress responses to capture and natural stress profiles of both captive and wild populations.

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Mann, Reinier M., Ross V. Hyne, Paulina Selvakumaraswamy, and Sergio S. Barbosa. "Longevity and larval development among southern bell frogs (Litoria raniformis) in the Coleambally Irrigation Area - implications for conservation of an endangered frog." Wildlife Research 37, no. 6 (2010): 447. http://dx.doi.org/10.1071/wr10061.

Повний текст джерела

Анотація:

Context. With the flow of many of the world’s rivers regulated such that water can be diverted for agriculture and human consumption, basic ecological information on the current status of key biota in significant floodplain wetlands and their response following inundation is needed. The maintenance of natural habitat to ensure amphibian survival is gaining increasing recognition, given the ongoing decline of anuran populations. Information on longevity, time required to emerge from the water and to reach sexual maturity, all provide important information about the required timing, frequency and duration of environmental water allocations to ensure successful recruitment among populations of southern bell frogs (Litoria raniformis Keferstein, 1867). Aims. The aims of this research were to establish the longevity of southern bell frogs in the Coleambally Irrigation Area (CIA) in the Riverina region of New South Wales, Australia, and to evaluate the capacity for southern bell frog tadpoles to survive and successfully metamorphose following an extended overwintering period. Methods. Skeletochronology studies were carried out using toe-clips taken from adult and juvenile frogs captured in irrigation channels and rice fields over two rice-growing seasons. For the metamorphosis assay, southern bell frog tadpoles were held back in their development by low temperatures and low food allocation for 290 days, before temperatures and food allocation were increased adequately to allow metamorphosis to occur. Key results. The study indicated that skeletochronological examination of toe-bones was a useful technique for establishing the age structure of southern bell frogs in this region. The oldest animals in the population were found to be 4–5 years old, although the majority of frogs were typically 2–3 years old. Also, the metamorphosis assay indicated that successful metamorphosis was the exception rather than the rule if tadpole development was held back by low food ration and low temperatures. Conclusions. If southern bell frogs reach sexual maturity only after 2 years, and the oldest animals observed in the field are 4 or 5 years old, then there is a very narrow window of opportunity – two to three seasons – for each individual to successfully breed. Implications. The implications for environmental flow management are that habitats for key species identified for protection such as the endangered southern bell frog will need water every 1–2 years to enable each cohort to breed and maintain the wild populations. The extent of the environmental flows needs to be adequate to ensure that water persists long enough for critical biological events such as anuran metamorphosis to occur during the spring and summer months.

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Kouba, A., E. Willis, C. Vance, S. Hasenstab, S. Reichling, J. Krebs, L. Linhoff, M. Snoza, C. Langhorne, and J. Germano. "116 DEVELOPMENT OF ASSISTED REPRODUCTION TECHNOLOGIES FOR THE ENDANGERED MISSISSIPPI GOPHER FROG (RANA SEVOSA) AND SPERM TRANSFER FOR IN VITRO FERTILIZATION." Reproduction, Fertility and Development 24, no. 1 (2012): 170. http://dx.doi.org/10.1071/rdv24n1ab116.

Повний текст джерела

Анотація:

Species-specific differences in breeding strategies and physiology have limited the application of assisted reproductive technologies (ART) for critically endangered amphibians in captive assurance colonies. In 2006, the Memphis Zoo (MZ) initiated a program to develop ART for the critically endangered Mississippi gopher frog after natural breeding failed. Standard gamete collection and IVF developed by MZ for reproducing endangered toads such as the Wyoming or boreal toad were applied to the gopher frog with little success, especially hormonal therapy for sperm production. Using the leopard frog as a model species for Ranids, we tested the time and dose dependence of a luteinizing hormone releasing hormone analogue (LHRHa) and hCG on sperm quantity and quality. Initial findings from the leopard frog study were critical in designing the study on gopher frogs. Our objectives were to (1) compare 2 different hormones administered intraperitoneal (500 IU hCG vs 15 μg LHRHa) or their combination on spermiation in gopher frogs; (2) develop in vivo oocyte maturation and ovulation protocols using LHRHa (15 μg) and hCG (500 IU); and (3) transfer this technology to another institution as proof of principle. In gopher frogs, 100 and 83% of the males produced sperm in response to the LHRHa and the combination treatment, respectively, whereas only 16% responded to hCG alone. Sperm concentration peaked at 1 h post-administration for all treatments, with the LHRH/hCG cocktail treatment producing the highest concentration of sperm (mean = 4.6 × 106 ± 1.2 × 106 sperm mL–1, n = 6). No differences in motility were observed between treatments (P > 0.05). For females, a series of priming hormones of hCG and LHRHa were given several months before an ovulatory hormone regimen resulting in ovulation by 100% of the females (n = 6), whereas animals not primed failed to ovulate (n = 4). These 3 separate priming and IVF trials conducted between 2008 and 2010 resulted in each female laying ∼2000 eggs, with an average fertilization rate of 76% for inseminated eggs and hundreds of tadpoles produced. These IVF tadpoles represent the first captive reproduction of gopher frogs and highlight how ART can be applied to conservation and genetic management of threatened species. Subsequently, we tested our IVF protocols on gopher frogs at Omaha's Henry Doorly Zoo using fresh (collected on site) and chilled, shipped sperm from MZ. We collected 6169 eggs from 9 hormone-primed females with all animals ovulating. A portion of the total eggs ovulated were inseminated, resulting in 2401 fertilized eggs (38.9% of total eggs collected) across 18 different male–female pairings leading to viable tadpoles. In addition, sperm transferred overnight from the MZ produced 202/441 fertilized eggs (46%). The transfer of this technology and production of endangered amphibians using chilled, shipped sperm from live animals is a conservation milestone that can be applied to other captive breeding programs.

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Pancharatna, Katti, Suresh Kumbar, and Sapna Chandran. "Phalangeal growth marks related to testis development in the frog Rana cyanophlyctis." Amphibia-Reptilia 21, no. 3 (2000): 371–79. http://dx.doi.org/10.1163/156853800507435.

Повний текст джерела

Анотація:

AbstractA study of phalangeal skeletochronology was performed to estimate the age of male frogs, Rana cyanophlyctis. Changes in testicular morphometry, kinetics of spermatogenesis and abdominal fat body mass were studied in relation to the number of growth marks in these frogs. Demineralized, stained cross- sections of distal phalanx of the 4th toe of male frogs showed growth rings that alternated with highly chromophilic lines of arrested growth (LAGs). One to five growth rings were observed in frogs with different body size; body mass (r = 0.44) and size (r = 0.47) showed poor correlation with the number of growth rings. Testicular morphometry, number of spermatogenic cysts per seminiferous tubule cross-section, and germ cells per cyst increased with the increase in the number of growth rings. Leydig cells were few in the frogs with a single growth ring and increased in second and third year but Sertoli cell number and nuclear diameter did not change drastically.

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Railsback, Steven F., Bret C. Harvey, Sarah J. Kupferberg, Margaret M. Lang, Scott McBain, and Hart H. Welsh. "Modeling potential river management conflicts between frogs and salmonids." Canadian Journal of Fisheries and Aquatic Sciences 73, no. 5 (May 2016): 773–84. http://dx.doi.org/10.1139/cjfas-2015-0267.

Повний текст джерела

Анотація:

Management of regulated rivers for yellow-legged frogs (Rana boylii) and salmonids exemplifies potential conflicts among species adapted to different parts of the natural flow and temperature regimes. Yellow-legged frogs oviposit in rivers in spring and depend on declining flows and warming temperatures for egg and tadpole survival and growth, whereas salmonid management can include high spring flows and low-temperature reservoir releases. We built a model of how flow and temperature affect frog breeding success. Its mechanisms include adults selecting oviposition sites to balance risks of egg dewatering by decreasing flow versus scouring by high flow, temperature effects on development, habitat selection by tadpoles, and mortality via dewatering and scouring. In simulations of a regulated river managed primarily for salmonids, below-natural temperatures delayed tadpole metamorphosis into froglets, which can reduce overwinter survival. However, mitigating this impact via higher temperatures was predicted to cause adults to oviposit before spring flow releases for salmonids, which then scoured the egg masses. The relative timing of frog oviposition and high flow releases appears critical in determining conflicts between salmonid and frog management.

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Duryee, William R. "FACTORS INFLUENCING DEVELOPMENT OF TUMORS IN FROGS*." Annals of the New York Academy of Sciences 126, no. 1 (December 16, 2006): 59–84. http://dx.doi.org/10.1111/j.1749-6632.1965.tb14268.x.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Davidson, Duncan. "Segmentation in frogs." Development 104, Supplement (October 1, 1988): 221–29. http://dx.doi.org/10.1242/dev.104.supplement.221.

Повний текст джерела

Анотація:

This paper reviews evidence relating to the question, at what stage in the development of the frog embryo are segment boundaries specified? Current evidence leads to the hypothesis that a spatiotemporal series of cell states leading to segmentation is continuously initiated at a position 200 to 300 μm from the posterior end of the presomitic mesoderm, about nine somite intervals before the formation of a definitive somite. The evidence suggests, though by no means proves, that segment boundaries are specified close to this time. This hypothesis relies critically on evidence concerning the effects of disruptive agents, the extent of cell mixing prior to the early gastrula stage, fate-map data, and a comparison with development in the mouse where a similar fate map can be related to morphological evidence of somitomeric segmentation. Evidence regarding the organization of the posterior, undifferentiated zone of the mesoderm in the frog embryo indicates that the cells are not proliferating rapidly, but are undergoing cell movements and rearrangements associated with caudal extension. The speculation that the segment pattern derives from inductive interactions in this region is discussed.

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Youngquist, Melissa B., and Michelle D. Boone. "Larval development and survival of pond-breeding anurans in an agricultural landscape impacted more by phytoplankton than surrounding habitat." PLOS ONE 16, no. 7 (July 26, 2021): e0255058. http://dx.doi.org/10.1371/journal.pone.0255058.

Повний текст джерела

Анотація:

The destruction of freshwater habitat is a major contributor to biodiversity loss in aquatic ecosystems. However, created or restored wetlands could partially mitigate aquatic biodiversity loss by increasing the amount of available habitat across a landscape. We investigated the impact of surrounding terrestrial habitat and water quality variables on suitability for two species of pond-breeding amphibians (bullfrogs [Lithobates catesbeianus] and Blanchard’s cricket frogs [Acris blanchardi]) in created permanent wetlands located on an agricultural landscape. We examined tadpole growth and survival in field enclosures placed in ponds surrounded by agricultural, forested, or grassland habitats. We also evaluated the potential for carryover effects of the aquatic environment on terrestrial growth and overwinter survival of cricket frog metamorphs. We found that habitat adjacent to ponds did not predict tadpole growth or survival. Rather, phytoplankton abundance, which showed high variability among ponds within habitat type, was the only predictor of tadpole growth. Cricket frogs emerged larger and earlier from ponds with higher phytoplankton abundance; bullfrogs were also larger and at a more advanced developmental stage in ponds with higher levels of phytoplankton. Overwinter survival of cricket frogs was explained by size at metamorphosis and there were no apparent carryover effects of land use or pond-of-origin on overwinter growth and survival. Our results demonstrate that created ponds in human-dominated landscapes can provide suitable habitat for some anurans, independent of the adjacent terrestrial habitat.

Стилі APA, Harvard, Vancouver, ISO та ін.

15

King, Richard B., and Bethia King. "Sexual differences in color and color change in wood frogs." Canadian Journal of Zoology 69, no. 7 (July 1, 1991): 1963–68. http://dx.doi.org/10.1139/z91-271.

Повний текст джерела

Анотація:

An observer-free method of color classification was used to determine whether wood frogs, Rana sylvatica, exhibit sexual differences in color and color change. Males and females captured from breeding aggregations differed significantly in color: females reflected a greater amount of long-wavelength (yellow–red) light and less short-wavelength (blue–green) light than males. The color difference was not just a result of differences in the state of physiological color change at the time of capture but persisted for a month after capture. Males and females also differed in their color-change responses to black and white backgrounds: both sexes changed in brightness, but only males changed in the relative amount of light reflected at different wavelengths. Wood frog color may function in predator avoidance through crypsis. There was a good match between frogs and some of the leaves from the leaf litter surrounding the breeding ponds. Hypotheses for the development of sexual differences in wood frog color include sexual differences in availability of pigment and pigment precursors, morphological color change, and evolutionary response to different selection pressures.

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Churchill, T. A., and K. B. Storey. "Dehydration tolerance in wood frogs: a new perspective on development of amphibian freeze tolerance." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 265, no. 6 (December 1, 1993): R1324—R1332. http://dx.doi.org/10.1152/ajpregu.1993.265.6.r1324.

Повний текст джерела

Анотація:

Wood frogs, Rana sylvatica, tolerate the loss of 50-60% of total body water during experimental dehydration. The rate of water loss for unprotected frogs is the same whether animals are frozen (at -2 degrees C) or unfrozen (at 1 degrees C) but is greatly reduced when frogs are frozen under a protective layer of moss. Dehydrational death could occur in as little as 7-9 days for unprotected animals; this indicates the importance for winter survival of selecting well-protected and damp hibernation sites. Prior dehydration affected the cooling and freezing properties of frogs, reducing supercooling point and the amount of ice formed after 24 h at -2 degrees C and acting synergistically with freezing exposure in stimulating cryoprotectant synthesis. Analysis of the effects of controlled dehydration at 5 degrees C showed that changes in body water content alone (without freezing) stimulated liver glycogenolysis and the export of high concentrations of glucose into blood and other organs. Autumn-collected frogs dehydrated to 50% of total body water lost showed glucose levels of 165-1,409 nmol/mg protein in different organs, increases of 9- to 313-fold compared with control values and reaching final levels very similar to those induced by freezing exposure. The data support the proposal that various adaptations for natural freeze tolerance may have been derived from preexisting mechanisms for dealing with water stress in amphibians and that cell volume change may be one of the signals involved in triggering and sustaining molecular adaptations (e.g., cryoprotectant output) that support freezing survival.

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Aaltonen, J. T., T. Bohlender, W. Snyder, J. Krebs, L. Linhoff, M. Snoza, S. Plesuk, et al. "120 THE DEVELOPMENTAL COMPETENCE OF TADPOLES PRODUCED IN VITRO FROM THE ENDANGERED DUSKY GOPHER FROG (RANA SEVOSA) USING EXOGENOUS HORMONE TREATMENT." Reproduction, Fertility and Development 24, no. 1 (2012): 172. http://dx.doi.org/10.1071/rdv24n1ab120.

Повний текст джерела

Анотація:

Dusky gopher frogs once existed throughout the states of Mississippi, Alabama and Louisiana. Presently, the USA Fish and Wildlife Service estimates that there are less than 100 frogs left in the wild, with almost all of these residing in a single pond in Mississippi, making the dusky gopher frog America's most endangered frog species. Their habitat has been threatened by residential and forestry development, as well as from fire suppression and the decline of gopher tortoises, whose burrows the frogs use for shelter. The USA Fish and Wildlife Service brought the first dusky gopher frogs into captivity in 2001 and they have been kept at the Memphis Zoo since 2003 and at Omaha's Henry Doorly Zoo since 2004. Natural breeding attempts in captivity have been unsuccessful despite efforts to artificially mimic what is known to be the appropriate seasonal environmental (e.g. light, humidity, temperature) and social cues (e.g. calls from wild frogs during the breeding season) that stimulate reproduction in situ. Also, there was a concern about the incidences of abnormalities (e.g. spindly legs) from inadequate husbandry conditions (e.g. nutritional deficiencies) or diseases in tadpoles and froglets produced ex situ (e.g. dermomycoides). The objectives of this study were (1) to examine the developmental competence of tadpoles produced by exogenous hormone treatment for IVF to complete normal metamorphosis into viable froglets ex situ and (2) to determine the incidence of developmental abnormalities or dermomycoides in the froglets produced ex situ. Males and females were first separated by the identification of black male nuptial pads used during amplexus. Males and females were stimulated to spermiate and ovulate, respectively, using a variation of a standard amphibian hormonal stimulation protocol (Kouba et al. 2012 Reprod. Fertil. Dev. 24). As a result, more than 1460 viable tadpoles (61% of fertilized eggs) were produced from 18 segregated genetic pairings. To date, 602 (41%) of the tadpoles have completed normal metamorphosis into viable froglets (over 6 times the known existing population in situ), 51% were either culled to examine for dermomycoides or died for a variety of known (accidental) and unknown reasons (abnormal appendage development accounting for less than 7%) and 8% have yet to metamorphose after 9 months. The incidence of dermomycoides in the culled individuals was 100%; however, a study being conducted concurrently in their native habitat has confirmed that the organism does exist in situ with the dusky gopher frogs, which act as natural carriers. Efforts are currently in place to establish reintroduction programs for the dusky gopher froglets produced ex situ to increase the dwindling wild population now that tadpoles produced by IVF have been shown to be developmentally competent. In conclusion, IVF can be used to produce tadpoles of the dusky gopher frog with a low incidence of abnormalities, but the tadpoles were found to be carriers of the organism dermomycoides similar to their counterparts in the wild.

Стилі APA, Harvard, Vancouver, ISO та ін.

18

DRYSDALE, THOMAS A., and RICHARD P. ELINSON. "Head Ectodermal Patterning and Axial Development in Frogs." American Zoologist 33, no. 4 (August 1993): 417–23. http://dx.doi.org/10.1093/icb/33.4.417.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Sachs, Laurent M., and Daniel R. Buchholz. "Frogs model man:In vivothyroid hormone signaling during development." genesis 55, no. 1-2 (January 2017): e23000. http://dx.doi.org/10.1002/dvg.23000.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Callery, Elizabeth M., Hung Fang, and Richard P. Elinson. "Frogs without polliwogs: Evolution of anuran direct development." BioEssays 23, no. 3 (February 13, 2001): 233–41. http://dx.doi.org/10.1002/1521-1878(200103)23:3<233::aid-bies1033>3.0.co;2-q.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

21

De S�, Rafael O., and Charles C. Swart. "Development of the suprarostral plate of Pipoid Frogs." Journal of Morphology 240, no. 2 (May 1999): 143–53. http://dx.doi.org/10.1002/(sici)1097-4687(199905)240:2<143::aid-jmor5>3.0.co;2-l.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Smith, James C. "Transgenic frogs and FGF signalling in early development." Trends in Genetics 12, no. 11 (November 1996): 439–40. http://dx.doi.org/10.1016/0168-9525(96)30105-4.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

23

DEL PINO, EUGENIA M. "Modifications of oogenesis and development in marsupial frogs." Development 107, no. 2 (October 1, 1989): 169–87. http://dx.doi.org/10.1242/dev.107.2.169.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Green, DM, and MP Simon. "Digital Microstructure in Ecologically Diverse Sympatric Microhylid Frogs, Genera Cophixalus and Sphenophryne (Amphibia, Anura), From Papua-New-Guinea." Australian Journal of Zoology 34, no. 2 (1986): 135. http://dx.doi.org/10.1071/zo9860135.

Повний текст джерела

Анотація:

The extent of development of digital adhesive toe-pads in sympatric species of microhylid frogs, Cophixalus and Sphenophryne, correlates with the degree of arboreality exhibited by the species. The same basic structures and cell types are found in the toe-pads of these microhylid frogs as are found in other arboreal and semi- arboreal frogs of many diverse evolutionary lineages. A variety of types of cell surface, with unknown functional significance but potential systematic use, are found on the feet of these frogs. Allometric increase in adhesive-pad area in larger species is by widening of the toe-pad, as opposed to acquisition of accessory pads as in some hylid tree frogs.

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Hawley, Tanya J. "Embryonic development and mortality in Hyalinobatrachium pulveratum (Anura: Centrolenidae) of south-western Costa Rica." Journal of Tropical Ecology 22, no. 6 (October 20, 2006): 731–34. http://dx.doi.org/10.1017/s0266467406003506.

Повний текст джерела

Анотація:

The population biology and ecology of most members of the neotropical family Centrolenidae, or glass frogs, are unknown. Glass frogs deposit their eggs in a gelatinous mass on vegetation overhanging streams, the eggs hatch, and the tadpoles drop into the water, where they complete development (Savage 2002). This study will contribute to our limited understanding of centrolenid reproductive ecology by quantifying variation in clutch size, embryonic development and embryonic mortality in a population of Hyalinobatrachium pulveratum.

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Kelleher, Shannon R., Aimee J. Silla, Petri T. Niemelä, Niels J. Dingemanse, and Phillip G. Byrne. "Dietary carotenoids affect the development of individual differences and behavioral plasticity." Behavioral Ecology 30, no. 5 (June 4, 2019): 1273–82. http://dx.doi.org/10.1093/beheco/arz074.

Повний текст джерела

Анотація:

AbstractNutritional conditions experienced during development are expected to play a key role in shaping an individual’s behavioral phenotype. The long term, irreversible effects of nutritional conditions on behavioral variation among and within individuals remains largely unexplored. This study aimed to investigate how long-term carotenoid availability (representing low vs. high quality nutritional conditions) during both larval and adult life stages influences the expression of among-individual variation (animal personality) and within-individual variation (behavioral plasticity). We tested for personality and plasticity along the exploration/avoidance behavioral axis in the Southern Corroboree frog (Pseudophryne corroboree). We predicted that treatment groups receiving carotenoids during early development would be more exploratory and have greater among- and within-individual variation compared with individuals that did not receive carotenoids (i.e., silver spoon hypothesis). Superior nutritional conditions experienced during development are expected to provide individuals with resources needed to develop costly behaviors, giving them an advantage later in life irrespective of prevailing conditions. Unexpectedly, frogs that did not receive carotenoids as larvae expressed greater among-individual variance in exploration behavior. Additionally, frogs that did not receive carotenoids at either life stage displayed greater within-individual variance. Our findings provide no support for the silver spoon hypothesis but suggest that inconsistent nutritional conditions between life stages may adversely affect the development of behavioral phenotypes. Overall, our results indicate that early and late life nutritional conditions affect the development of personality and plasticity. They also highlight that nutritional effects on behavior may be more complex than previously theorized.

Стилі APA, Harvard, Vancouver, ISO та ін.

27

Sun, Yan-Bo, Zi-Jun Xiong, Xue-Yan Xiang, Shi-Ping Liu, Wei-Wei Zhou, Xiao-Long Tu, Li Zhong, et al. "Whole-genome sequence of the Tibetan frog Nanorana parkeri and the comparative evolution of tetrapod genomes." Proceedings of the National Academy of Sciences 112, no. 11 (March 2, 2015): E1257—E1262. http://dx.doi.org/10.1073/pnas.1501764112.

Повний текст джерела

Анотація:

The development of efficient sequencing techniques has resulted in large numbers of genomes being available for evolutionary studies. However, only one genome is available for all amphibians, that of Xenopus tropicalis, which is distantly related from the majority of frogs. More than 96% of frogs belong to the Neobatrachia, and no genome exists for this group. This dearth of amphibian genomes greatly restricts genomic studies of amphibians and, more generally, our understanding of tetrapod genome evolution. To fill this gap, we provide the de novo genome of a Tibetan Plateau frog, Nanorana parkeri, and compare it to that of X. tropicalis and other vertebrates. This genome encodes more than 20,000 protein-coding genes, a number similar to that of Xenopus. Although the genome size of Nanorana is considerably larger than that of Xenopus (2.3 vs. 1.5 Gb), most of the difference is due to the respective number of transposable elements in the two genomes. The two frogs exhibit considerable conserved whole-genome synteny despite having diverged approximately 266 Ma, indicating a slow rate of DNA structural evolution in anurans. Multigenome synteny blocks further show that amphibians have fewer interchromosomal rearrangements than mammals but have a comparable rate of intrachromosomal rearrangements. Our analysis also identifies 11 Mb of anuran-specific highly conserved elements that will be useful for comparative genomic analyses of frogs. The Nanorana genome offers an improved understanding of evolution of tetrapod genomes and also provides a genomic reference for other evolutionary studies.

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Hu, Fang, Erica J. Crespi, and Robert J. Denver. "Programming Neuroendocrine Stress Axis Activity by Exposure to Glucocorticoids during Postembryonic Development of the Frog, Xenopus laevis." Endocrinology 149, no. 11 (July 24, 2008): 5470–81. http://dx.doi.org/10.1210/en.2008-0767.

Повний текст джерела

Анотація:

Exposure to elevated glucocorticoids during early mammalian development can have profound, long-term consequences for health and disease. However, it is not known whether such actions occur in nonmammalian species, and if they do, whether the molecular physiological mechanisms are evolutionarily conserved. We investigated the effects of dietary restriction, which elevates endogenous corticosterone (CORT), or exposure to exogenous CORT added to the aquarium water of Xenopus laevis tadpoles on later-life measures of growth, feeding behavior, and neuroendocrine stress axis activity. Dietary restriction of prometamorphic tadpoles reduced body size at metamorphosis, but juvenile frogs increased food intake, showed catch-up growth through 21 d after metamorphosis, and had elevated whole-body CORT content compared with controls. Dietary restriction causes increased CORT in tadpoles, so to mimic this increase, we treated tadpoles with 100 nm CORT or vehicle for 5 or 10 d and then reared juvenile frogs to 2 months after metamorphosis. Treatment with CORT decreased body weight at metamorphosis, but juvenile frogs showed catch-up growth and had elevated basal plasma (CORT). Immunohistochemical analysis showed that CORT exposure as a tadpole led to decreased glucocorticoid receptor immunoreactivity in brain regions involved with stress axis regulation and in the anterior pituitary gland of juvenile frogs. The elevated CORT in juvenile frogs, which could result from decreased negative feedback owing to down-regulation of glucocorticoid receptor, may drive the hyperphagic response. Taken together, our findings suggest that long-term, stable phenotypic changes in response to elevated glucocorticoids early in life are an ancient and conserved feature of the vertebrate lineage.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Gollmann, Günter, and Birgit Gollmann. "Embryonic development of the myobatrachine frogs Geocrinia laevis, Geocrinia victoriana, and their natural hybrids." Amphibia-Reptilia 12, no. 1 (1991): 103–10. http://dx.doi.org/10.1163/156853891x00365.

Повний текст джерела

Анотація:

AbstractThe Australian frogs Geocrinia laevis and Geocrinia victoriana undergo prolonged embryonic development inside their egg capsules, before hatching as advanced tadpoles. Despite the presence of large amounts of yolk, the course of development follows the typical anuran pattern rather closely, and is essentially identical in the two species and their natural hybrids. We present a modification of Gosner's (1960) staging table, using mainly changes in the eye and the mouthparts to define stages (20 to 26) in a phase of development, when the Gosner table is not applicable to myobatrachine frogs.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Vallejos, Johana Goyes, and Karim Ramirez-Soto. "Causes of embryonic mortality in Espadarana prosoblepon (Anura: Centrolenidae) from Costa Rica." Phyllomedusa: Journal of Herpetology 19, no. 1 (June 29, 2020): 83–92. http://dx.doi.org/10.11606/issn.2316-9079.v19i1p83-92.

Повний текст джерела

Анотація:

Causes of embryonic mortality in Espadarana prosoblepon (Anura: Centrolenidae) from Costa Rica. Members of the family Centrolenidae—commonly known as “glass frogs”—exhibit arboreal egg-laying behavior, depositing their clutches on riparian vegetation. Few studies have investigated specific causes of mortality during embryonic stages, perhaps the most vulnerable stage during the anuran life cycle. The Emerald Glass Frog, Espadarana prosoblepon, was used as a case study to investigate the causes of embryonic mortality in a species with short-term (i.e., less than 1 day) parental care. The specific sources of mortality of eggs of E. prosoblepon were quantified and overall rates of survival (hatching success) were estimated. Nineteen egg clutches were transferred from permanent outside enclosures to the wild. Clutch development was monitored daily until hatching; five mortality causes were quantified: desiccation, failure to develop, fungal infection, predation, and “rain-stripped.” The main causes of mortality were predation (often by katydids and wasps) and embryos stripped from the leaf during heavy rains. The results were compared to those of previous studies of centrolenids exhibiting parental care, and discussed in the context of the importance of the natural history data for these frogs with regard to understanding the evolutionary history of parental care in glass frogs.

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Rollins-Smith, Louise A., Martin F. Flajnik, Patrick J. Blair, A. Tray Davis, and Wayne F. Green. "Involvement of Thyroid Hormones in the Expression of MHC class I Antigens During Ontogeny inXenopus." Developmental Immunology 5, no. 2 (1997): 133–44. http://dx.doi.org/10.1155/1997/38464.

Повний текст джерела

Анотація:

The major histocompatibility complex (MHC) is a cluster of genes encoding products central to all major functions of the vertebrate immune system. Evidence for an MHC can be found in all vertebrate groups that have been examined except the jawless fishes. Expression of MHC class I and class II antigens early in ontogeny is critically important for development of T lymphocytes capable of discriminating self from nonself. Because of this essential role in T-cell development, the ontogeny of MHC expression in the South African clawed frog,Xenopus laevis, was studied. Previous studies of MHC class I expression inXenopus laevissuggested that class I antigens are virtually absent from tadpole tissues until climax of metamorphosis. We therefore examined the possible role of thyroid hormones (TH) in the induction of class I. By flow cytometry, a small amount of class I expression was detectable on splenocytes and erythrocytes in untreated frogs at prometamorphic stages 55-58, and the amount increased significantly at the conclusion of metamorphic climax. Thus, metamorphosis is associated with increased intensity of class I expression. Neither inhibition nor acceleration of metamorphosis altered the timing of onset of class I expression. However, inhibition of metamorphosis prevented the increase in class I expression characteristic of adult cell populations. Because expression was not accelerated in TH-treated frogs or delayed in metamorphosis-inhibited frogs, it is unlikely that TH are the direct developmental cues that induce expression, although they seem to be required for the upregulation of class I expression occurring at metamorphosis. Differences in the pattern of expression in different subpopulations of cells suggest a complex pattern of regulation of expression of class I antigens during ontogeny.

Стилі APA, Harvard, Vancouver, ISO та ін.

32

ANSTIS, MARION, FRED PARKER, TIM HAWKES, IAN MORRIS, and STEPHEN J. RICHARDS. "Direct development in some Australopapuan microhylid frogs of the genera Austrochaperina, Cophixalus and Oreophryne (Anura: Microhylidae) from northern Australia and Papua New Guinea." Zootaxa 3052, no. 1 (October 7, 2011): 1. http://dx.doi.org/10.11646/zootaxa.3052.1.1.

Повний текст джерела

Анотація:

Embryonic development in fifteen Australopapuan microhylid frogs of the genera Austrochaperina, Cophixalus and Oreophryne is described. These frogs have direct development during which the embryo develops to a minute froglet within the jelly capsule. Development of the operculum, presence of external gills, tail structure, gut development and timing of forelimb emergence are described and compared with the direct-developing eleutherodactylid Eleutherodactylus coqui from Puerto Rico and three Australian myobatrachid genera with direct development (Arenophryne, Metacrinia and Myobatrachus). We comment on those differences that likely reflect examples of convergent and divergent evolution and heterochrony.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Ziermann, Janine M., and Rui Diogo. "Cranial muscle development in frogs with different developmental modes: Direct development versus biphasic development." Journal of Morphology 275, no. 4 (December 3, 2013): 398–413. http://dx.doi.org/10.1002/jmor.20223.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Vásquez-Cruz, Víctor, Luis Canseco-Márquez, and Arleth Reynoso-Martínez. "Distributional and natural history notes for Bromeliohyla dendroscarta (Anura: Hylidae) in Veracruz, Mexico." Phyllomedusa: Journal of Herpetology 18, no. 1 (June 18, 2019): 27–36. http://dx.doi.org/10.11606/issn.2316-9079.v18i1p27-36.

Повний текст джерела

Анотація:

Distributional and natural history notes for Bromeliohyla dendroscarta (Anura: Hylidae) in Veracruz, Mexico. Two new locality records are reported for the critically endangered hylid frog, Bromeliohyla dendroscarta, in Veracruz, Mexico. The frogs were found in semideciduous tropical forest, an ecotone of semideciduous tropical forest and mountain cloud forest, and an agricultural mosaic; none of these habitats has been documented previously for this species. Information is provided on larval feeding habits, duration of larval development under natural conditions and external morphology of tadpoles.

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Tasse Taboue, Geraud Canis, and Eric Bertrand Fokam. "Life History of the Golden Puddle Frog, Phrynobatrachus auritus Boulenger 1900 (Anura: Phrynobatrachidae)." International Journal of Biology 8, no. 3 (June 27, 2016): 77. http://dx.doi.org/10.5539/ijb.v8n3p77.

Повний текст джерела

Анотація:

Frogs of the genus <em>Phrynobatrachus </em>Günther, 1862 are endemic to sub-Saharan Africa. These are increasingly threatened by a number of factors and are believed to be declining. We report on captive breeding experiments involving <em>Phrynobatrachus auritus</em> Boulenger, 1900. We provide a comprehensive life history for this frog with emphasize on tadpole development time, as well as a description of both the advertisement call and calling behaviour of the adult.

Стилі APA, Harvard, Vancouver, ISO та ін.

36

HEINICKE, MATTHEW P., WILLIAM E. DUELLMAN, LINDA TRUEB, D. BRUCE MEANS, ROSS D. MacCULLOCH, and S. BLAIR HEDGES. "A new frog family (Anura: Terrarana) from South America and an expanded direct-developing clade revealed by molecular phylogeny." Zootaxa 2211, no. 1 (August 27, 2009): 1–35. http://dx.doi.org/10.11646/zootaxa.2211.1.1.

Повний текст джерела

Анотація:

Three frogs of a new species found in cloud forests on two nearby mountains in Guyana were included in a molecular phylogeny of 17 nuclear and mitochondrial genes (10,739 aligned sites) that revealed that their closest relative is Terrarana (Brachycephalidae, Craugastoridae, Eleutherodactylidae, and Strabomantidae) and their next-closest relative is Hemiphractidae (marsupial frogs). We place these frogs in a new family, genus, and species which is strongly supported as the basal clade within Terrarana: Ceuthomantidae n. fam., Ceuthomantis smaragdinus n. gen, n. sp. Morphological evidence supports the placement of two other species from the Guiana Highlands, Pristimantis aracamuni (BarrioAmorós & Molina) and P. cavernibardus (Myers & Donnelly), in the new family and genus. This close phylogenetic relationship of terraranans and marsupial frogs, nearly all of which have direct development, supports an hypothesis that direct development evolved early in the evolution of this huge clade (~1000 species), for which we propose the unranked taxonomic epithet Orthobatrachia.

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Schlosser, Gerhard, and Gerhard Roth. "Evolution of Nerve Development in Frogs; pp. 61–73." Brain, Behavior and Evolution 50, no. 2 (1997): 61–73. http://dx.doi.org/10.1159/000113323.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Schlosser, Gerhard, and Gerhard Roth. "Evolution of Nerve Development in Frogs; pp. 74–83." Brain, Behavior and Evolution 50, no. 2 (1997): 74–83. http://dx.doi.org/10.1159/000113324.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Schlosser, Gerhard, and Gerhard Roth. "Evolution of Nerve Development in Frogs; pp. 94–112." Brain, Behavior and Evolution 50, no. 2 (1997): 94–112. http://dx.doi.org/10.1159/000113325.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Schlosser, Gerhard, and Gerhard Roth. "Evolution of Nerve Development in Frogs; pp. 112–128." Brain, Behavior and Evolution 50, no. 2 (1997): 112–28. http://dx.doi.org/10.1159/000113326.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Schlosser, Gerhard, and Gerhard Roth. "Evolution of Nerve Development in Frogs; pp. 84–93." Brain, Behavior and Evolution 50, no. 2 (1997): 84–93. http://dx.doi.org/10.1159/000316296.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Nokhbatolfoghahai, M., and J. R. Downie. "Larval cement gland of frogs: Comparative development and morphology." Journal of Morphology 263, no. 3 (2005): 270–83. http://dx.doi.org/10.1002/jmor.10305.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Sudou, Norihiro, Andrés Garcés-Vásconez, María A. López-Latorre, Masanori Taira, and Eugenia M. del Pino. "Transcription factors Mix1 and VegT, relocalization of vegt mRNA, and conserved endoderm and dorsal specification in frogs." Proceedings of the National Academy of Sciences 113, no. 20 (May 2, 2016): 5628–33. http://dx.doi.org/10.1073/pnas.1605547113.

Повний текст джерела

Анотація:

Protein expression of the transcription factor genes mix1 and vegt characterized the presumptive endoderm in embryos of the frogs Engystomops randi, Epipedobates machalilla, Gastrotheca riobambae, and Eleutherodactylus coqui, as in Xenopus laevis embryos. Protein VegT was detected in the animal hemisphere of the early blastula in all frogs, and only the animal pole was VegT-negative. This finding stimulated a vegt mRNA analysis in X. laevis eggs and embryos. vegt mRNA was detected in the animal region of X. laevis eggs and early embryos, in agreement with the VegT localization observed in the analyzed frogs. Moreover, a dorso-animal relocalization of vegt mRNA occurred in the egg at fertilization. Thus, the comparative analysis indicated that vegt may participate in dorsal development besides its known roles in endoderm development, and germ-layer specification. Zygotic vegt (zvegt) mRNA was detected as a minor isoform besides the major maternal (mvegt) isoform of the X. laevis egg. In addition, α-amanitin–insensitive vegt transcripts were detected around vegetal nuclei of the blastula. Thus, accumulation of vegt mRNA around vegetal nuclei was caused by relocalization rather than new mRNA synthesis. The localization of vegt mRNA around vegetal nuclei may contribute to the identity of vegetal blastomeres. These and previously reportedly localization features of vegt mRNA and protein derive from the master role of vegt in the development of frogs. The comparative analysis indicated that the strategies for endoderm, and dorsal specification, involving vegt and mix1, have been evolutionary conserved in frogs.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Drotlef, Dirk M., Esther Appel, Henrik Peisker, Kirstin Dening, Aránzazu del Campo, Stanislav N. Gorb, and W. Jon P. Barnes. "Morphological studies of the toe pads of the rock frog, Staurois parvus (family: Ranidae) and their relevance to the development of new biomimetically inspired reversible adhesives." Interface Focus 5, no. 1 (February 6, 2015): 20140036. http://dx.doi.org/10.1098/rsfs.2014.0036.

Повний текст джерела

Анотація:

The morphology of the toe epithelium of the rock frog, Staurois parvus (Family Ranidae), was investigated using a variety of microscopical techniques. The toe pad epithelium is stratified (four to five cell layers), the apical parts of the cells of the outermost layer being separated by fluid-filled channels. The surface of these cells is covered by a dense array of nanopillars, which also cover the surface of subarticular tubercles and unspecialized ventral epithelium of the toes, but not the dorsal epithelium. The apical portions of the outer two layers contain fibrils that originate from the nanopillars and are oriented approximately normal to the surface. This structure is similar to the pad structure of tree frogs of the families Hylidae and Rhacophoridae, indicating evolutionary convergence and a common evolutionary design for reversible attachment in climbing frogs. The main adaptation to the torrent habitat seems to be the straightness of the channels crossing the toe pad, which will assist in drainage of excess water. The presence of nanopillar arrays on all ventral surfaces of the toes resembles that on clingfish suckers and may be a specific adaptation for underwater adhesion and friction. The relevance of these findings to the development of new biomimetically inspired reversible adhesives is discussed.

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Fort, Douglas J., Sigmund Degitz, Joseph Tietge, and Leslie W. Touart. "The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Frogs and Its Role in Frog Development and Reproduction." Critical Reviews in Toxicology 37, no. 1-2 (January 2007): 117–61. http://dx.doi.org/10.1080/10408440601123545.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Rojahn, Jack, Dianne Gleeson, and Elise M. Furlan. "Monitoring post-release survival of the northern corroboree frog, Pseudophryne pengilleyi, using environmental DNA." Wildlife Research 45, no. 7 (2018): 620. http://dx.doi.org/10.1071/wr17179.

Повний текст джерела

Анотація:

Context Translocations are becoming an increasingly important conservation tool to combat rising levels of species extinction. Unfortunately, many translocation efforts fail; yet, the timing and cause of failure often remain unknown. Monitoring individuals in the days and weeks following release can provide valuable information on their capacity to survive this initial hurdle. In Australia, breeding programs have been established for the endangered northern corroboree frog, Pseudophryne pengilleyi, to enable reintroduction to the wild via captive-reared individuals, typically, early life stages such as eggs or juvenile frogs that cannot be monitored via traditional survey methods that target adult frogs (e.g. shout–response). Environmental DNA (eDNA) detects trace amounts of DNA that organisms release into their environment and could provide a means to infer population persistence for wildlife releases and translocations. Aims In the present study, we aim to develop an eDNA assay capable of detecting both sexes of P. pengilleyi across multiple life stages, and use it to monitor their survival. Methods An eDNA assay was developed to target the two corroboree frog species (P. pengilleyi and P. corroboree, the southern corroboree frog) and was tested for its sensitivity and specificity in silico and in vitro. Pseudophryne pengilleyi eggs were released into three naturally occurring ponds and water samples were, subsequently, collected from each pond on several occasions over a period of 78 days. Quantitative polymerase chain reaction was used to detect P. pengilleyi eDNA from water samples. Key Results The developed assay was shown to be sensitive and specific to corroboree frogs. eDNA monitoring of reintroduced P. pengilleyi detected the species’ DNA at three of three release ponds and DNA remained detectable until at least 78 days post-release at two of three ponds. Conclusions We show how the development of a corroboree frog-specific assay allowed us to monitor the post-release survival of P. pengilleyi in naturally occurring pools. Implications eDNA surveys may provide a useful tool to monitor post-release survival of translocated populations in a non-invasive manner, with the potential to identify the timing and causes of failure. Such knowledge can be used to inform the management of translocated populations and future release strategies.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

Buddington, R. K., J. W. Chen, and J. M. Diamond. "Dietary regulation of intestinal brush-border sugar and amino acid transport in carnivores." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 261, no. 4 (October 1, 1991): R793—R801. http://dx.doi.org/10.1152/ajpregu.1991.261.4.r793.

Повний текст джерела

Анотація:

The ability of omnivores and herbivores to regulate reversibly their intestinal brush-border nutrient transporters is functionally related to the unpredictably variable composition of their natural diets. To determine whether carnivores are able similarly to regulate the activities of their intestinal nutrient transporters, we fed to three species of vertebrates that are carnivorous as adults (cats, mink, and leopard frogs) diets with either at least 50% digestible carbohydrate or with negligible carbohydrate levels. Rates of transport for the sugars glucose and fructose and the amino acids (AAs) aspartate, leucine, lysine, and proline were measured throughout the intestine (only proline and glucose in the frogs) by an in vitro everted-sleeve method. Although all three species consume much carbohydrate during early development, only the mink was able to regulate sugar transporter activity in response to changes in levels of dietary carbohydrate. In contrast, the sugar transporters of the cat were unresponsive to varying carbohydrate levels, and long-term feeding of a high-carbohydrate diet caused down-regulation of sugar transport in frogs. Of the three species, only the mink is a member of a family that includes omnivorous species, whereas all members of the families to which the cat and frog belong are carnivorous as adults. All three species were able to regulate rates of AA transport, though the patterns and magnitude of the responses differed between species as well as between AAs, suggesting independent regulation of some AA transporters.(ABSTRACT TRUNCATED AT 250 WORDS)

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Ueno, S., T. Kitahara, K. Harada, and K. Shiokawa. "Embryonic development of frogs under EFL magnetic or electric fields." Journal of the Magnetics Society of Japan 10, no. 2 (1986): 383–86. http://dx.doi.org/10.3379/jmsjmag.10.383.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Ueno, S., T. Kitahara, K. Harada, and K. Shiokawa. "Embryonic Development of Frogs Under ELF Magnetic or Electric Fields." IEEE Translation Journal on Magnetics in Japan 2, no. 9 (September 1987): 859–60. http://dx.doi.org/10.1109/tjmj.1987.4549633.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Baugh, Alexander T., and Michael J. Ryan. "The development of sexual behavior in túngara frogs (Physalaemus pustulosus)." Journal of Comparative Psychology 124, no. 1 (2010): 66–80. http://dx.doi.org/10.1037/a0017227.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Статті в журналах з теми "Frogs Development"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями