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Cytochrome P450 (CYP) enzymes are crucial for the detoxification of xenobiotics, cellular metabolism, and homeostasis. This study investigated the molecular characterization of CYP enzymes in the black-spotted frog, Pelophylax nigromaculatus, and examined the regulation of CYP expression in response to chronic exposure to the antibiotic sulfamethoxazole (SMX) at various environmental concentrations (0, 1, 10, and 100 μg/L). The full-length cDNA of Pn-CYP26B1 was identified. The sequence included open reading frames of 1,536 bp, encoding proteins comprising 511 amino acids. The signature motif, FxxGxxxCxG, was highly conserved when compared with a number of selected animal species. SMX significantly upregulated the expression of the protein CYP26B1 in frog livers at concentrations of 1 and 10 μg/L. SMX showed an affinity for CYP26B1 of -7.6 kcal/mol, indicating a potential mechanism for SMX detoxification or adaptation of the frog. These findings contributed to our understanding of the environmental impact of antibiotics on amphibian species and underscored the importance of CYP enzymes in maintaining biochemical homeostasis under exposure to xenobiotic stress. [ABSTRACT FROM AUTHOR]

Simple Summary: Understanding how traits evolve across different life stages is crucial for species with complex life cycles. We investigated how tadpole morphology relates to adult shape in Neoaustrarana frogs, finding that larval and adult shapes show low correlation. Our study, encompassing 83 species across four families, highlights the importance of considering ontogenetic stages in evolutionary research. We observed distinct patterns among families, with larval morphospace exhibiting higher phylogenetic structure than adult morphospace. Our results support the Adaptive Decoupling Hypothesis as a mechanism driving phenotypic diversity, shedding light on the early evolution of Neoaustrarana frogs and emphasizing the need for further research in this area. Phenotypic traits can evolve independently at different stages of ontogeny, optimizing adaptation to distinct ecological contexts and increasing morphological diversity in species with complex life cycles. Given the relative independence resulting from the profound changes induced by metamorphosis, niche occupation and resource utilization in tadpoles may prompt evolutionary responses that do not necessarily affect the adults. Consequently, diversity patterns observed in the larval shape may not necessarily correspond to those found in the adult shape for the same species, a premise that can be tested through the Adaptive Decoupling Hypothesis (ADH). Herein, we investigate the ADH for larval and adult shape differentiation in Neoaustrarana frogs. Neoaustrarana frogs, particularly within the Cycloramphidae family, exhibit remarkable diversity in tadpole morphology, making them an ideal model for studying adaptive decoupling. By analyzing 83 representative species across four families (Alsodidae, Batrachylidae, Cycloramphidae, and Hylodidae), we generate a morphological dataset for both larval and adult forms. We found a low correlation between larval and adult shapes, species with a highly distinct larval shape having relatively similar shape when adults. Larval morphological disparity is not a good predictor for adult morphological disparity within the group, with distinct patterns observed among families. Differences between families are notable in other aspects as well, such as the role of allometric components influencing shape and morphospace occupancy. The larval shape has higher phylogenetic structure than the adult. Evolutionary convergence emerges as a mechanism of diversification for both larval and adult shapes in the early evolution of neoaustraranans, with shape disparity of tadpoles reaching stable levels since the Oligocene. The widest occupation in morphospace involves families associated with dynamically changing environments over geological time. Our findings support the ADH driving phenotypic diversity in Neoaustrarana, underscoring the importance of considering ontogenetic stages in evolutionary studies. [ABSTRACT FROM AUTHOR]

Flexible job shop scheduling problem (FJSP), widely prevalent in many intelligent manufacturing industries, is one of the most classic problems of production scheduling and combinatorial optimization. In actual manufacturing enterprises, the setup of machines and the handling of jobs have an important impact on the scheduling plan. Furthermore, there is a trend for a cluster of machines with similar functionalities to form a work center. Considering the above constraints, a new order-driven multi-equipment work center FJSP model with setup and handling including multiple objectives encompassing the minimization of the makespan, the number of machine shutdowns, and the number of handling batches is established. An improved shuffled frog leading algorithm is designed to solve it through the optimization of the initial solution population, the improvement of evolutionary operations, and the incorporation of Pareto sorting. The algorithm also combines the speed calculation method in the gravity search algorithm to enhance the stability of the solution search. Some standard FJSP data benchmarks have been selected to evaluate the effectiveness of the algorithm, and the experimental results confirm the satisfactory performance of the proposed algorithm. Finally, a problem example is designed to demonstrate the algorithm's capability to generate an excellent scheduling plan. [ABSTRACT FROM AUTHOR]

Amphibians are routinely collected from the wild and added into managed care and public display facilities; however, there is a gap in understanding how these practices might alter the diversity and composition of skin microbial communities on these animals. The aim of this study was to evaluate and compare skin microbial communities of spring peeper frogs (Pseudacris crucifer) from acquisition in the wild through the end of their quarantine period and identify microbial taxa with antifungal properties. From an original group of seventy-six frogs, cohorts of ten were swabbed when acquired in the wild, upon transport from the wild, and swabbed throughout a 9-week quarantine period while under managed care. An immediate loss of microbial richness and diversity was evident upon transfer of the frogs from their original environment and continued throughout subsequent sampling time-points during quarantine. Importantly, antifungal taxa comprised significantly more of the overall skin community after the frogs were moved from the wild, largely due to members of the family Moraxellaceae. Overall, our findings demonstrate that amphibian skin microbiome changes immediately on removal from the wild, and that these changes persist throughout quarantine while being housed under managed care. This may play a pivotal role in the development of dermatological disease and have implications in the health and immune function of amphibians. [ABSTRACT FROM AUTHOR]

Autonomous sensors provide opportunities to observe organisms across spatial and temporal scales that humans cannot directly observe. By processing large data streams from autonomous sensors with deep learning methods, researchers can make novel and important natural history discoveries. In this study, we combine automated acoustic monitoring with deep learning models to observe breeding-associated activity in the endangered Sierra Nevada yellow-legged frog (Rana sierrae), a behavior that current surveys do not measure. By deploying inexpensive hydrophones and developing a deep learning model to recognize breeding-associated vocalizations, we discover three undocumented R. sierrae vocalization types and find an unexpected temporal pattern of nocturnal breeding-associated vocal activity. This study exemplifies how the combination of autonomous sensor data and deep learning can shed new light on species' natural history, especially during times or in locations where human observation is limited or impossible. [ABSTRACT FROM AUTHOR]

Amphibians are declining worldwide, and research on their habitats and ecology is important for their conservation. The endangered dusky gopher frog (Rana sevosa) breeds exclusively in isolated, open canopy wetlands, usually with extensive herbaceous growth. Larvae of the dusky gopher frog have higher growth and survival under open canopy than under closed canopy conditions. The mechanisms whereby this occurs are poorly understood, however. In the summer of 2021 in Harrison County, Mississippi, USA, we conducted a complete factorial experiment in mesocosms to compare the relative influence of factors differing between open and closed canopy ponds on larvae. A heat and light treatment consisted of one third of tanks being exposed to full sunlight, one third of tanks being shaded with 70% shadecloth, and the final third being shaded with 70% shadecloth but heated to mimic the temperature of the full sun tanks. In addition, tanks received a closed canopy tree leaf litter mixture or an open canopy herbaceous vegetation mixture, and vertical vegetation‐like structure made of polypropylene rope or not. Cool shaded tanks and heated shaded tanks had identical survival to metamorphosis at 74.7% and produced frogs with an average mass of 2.21 g and 2.09 g, respectively, while tanks in full sunlight achieved significantly higher 93.4% survival to metamorphosis and an average mass of 2.64 g. The open canopy vegetation mixture yielded an average tank survival of 88.3% and mass of 2.94 g, compared to closed canopy vegetation tanks with a significantly lower survival of 73.5% and average mass of 1.61 g. Added structure had no effect on survival or mass. These results indicate that sunlight (not heat alone) and herbaceous plants are important in increasing dusky gopher frog survival and mass in open canopy conditions and suggest that management for these characteristics receive priority in captive‐rearing programs and habitat restoration. [ABSTRACT FROM AUTHOR]

Railroad turnouts are an essential element of the track infrastructure that facilitates the movement of trains between adjacent or diverging tracks. Turnout frogs are subjected to high wheel impact forces due to the inherent need for a discontinuity in their geometry. To develop an optimised frog geometry to minimise wheel impacts, a parametric study was designed and executed that considered three critical design parameters: point (i.e. nose) slope, relative height difference between wing and point, and longitudinal wing slope. Four hundred wheel profiles were extracted from a dataset of one million revenue service wheel profiles based on a wheel classification methodology previously developed. Wheel impact was quantified for each frog geometry case based on wheel transfer distribution and vertical wheel trajectory which were analysed using a developed Python algorithm. A total of 30 unique geometries were evaluated, including the existing standard design geometry for a N.A. heavy point conformal frog. Results demonstrated that each parameter affects different locations along the frog and total impact is most affected by point slope. Lastly, an optimised frog geometry was selected that ensures well-distributed wheel transfer locations preventing the concentration of damage, and results in low total impact at the transfer point. [ABSTRACT FROM AUTHOR]

Frog virus 3 (FV3) in the genus Ranavirus of the family Iridoviridae causes mass mortality in both anurans and urodeles worldwide; however, the phylogenetic origin of FV3-like ranaviruses is not well established. In Asia, three FV3-like ranaviruses have been reported in farmed populations of amphibians and reptiles. Here, we report the first case of endemic FV3-like ranavirus infections in the Korean clawed salamander Onychodactylus koreanus, caught in wild mountain streams in the Republic of Korea (ROK), through whole-genome sequencing and phylogenetic analysis. Two isolated FV3-like ranaviruses (Onychodactylus koreanus ranavirus, OKRV1 and 2) showed high similarity with the Rana grylio virus (RGV, 91.5%) and Rana nigromaculata ranavirus (RNRV, 92.2%) but relatively low similarity with the soft-shelled turtle iridovirus (STIV, 84.2%) in open reading frame (ORF) comparisons. OKRV1 and 2 formed a monophyletic clade with previously known Asian FV3-like ranaviruses, a sister group of the New World FV3-like ranavirus clade. Our results suggest that OKRV1 and 2 are FV3-like ranaviruses endemic to the ROK, and RGV and RNRV might also be endemic strains in China, unlike previous speculation. Our data have great implications for the study of the phylogeny and spreading routes of FV3-like ranaviruses and suggest the need for additional detection and analysis of FV3-like ranaviruses in wild populations in Asian countries. [ABSTRACT FROM AUTHOR]

Although behavioural defensive responses have been recorded several times in both laboratory and natural habitats, their neural mechanisms have seldom been investigated. To explore how chemical, water-borne cues are conveyed to the forebrain and instruct behavioural responses in anuran larvae, we conditioned newly hatched agile frog tadpoles using predator olfactory cues, specifically either native odonate larvae or alien crayfish kairomones. We expected chronic treatments to influence the basal neuronal activity of the tadpoles' mitral cells and alter their sensory neuronal connections, thereby impacting information processing. Subsequently, these neurons were acutely perfused, and their responses were compared with the defensive behaviour of tadpoles previously conditioned and exposed to the same cues. Tadpoles conditioned with odonate cues differed in both passive and active cell properties compared to those exposed to water (controls) or crayfish cues. The observed upregulation of membrane conductance and increase in both the number of active synapses and receptor density at the postsynaptic site are believed to have enhanced their responsiveness to external stimuli. Odonate cues also affected the resting membrane potential and firing rate of mitral cells during electrophysiological patch-clamp recordings, suggesting a rearrangement of the repertoire of voltage-dependent conductances expressed in cell membranes. These recorded neural changes may modulate the induction of an action potential and transmission of information. Furthermore, the recording of neural activity indicated that the lack of defensive responses towards non-native predators is due to the non-recognition of their olfactory cues. [ABSTRACT FROM AUTHOR]

Toxicity has evolved multiple times across the tree of life and serves important functions related to hunting, defence and parasite deterrence. Toxins are produced either in situ by the toxic organism itself or associated symbionts, or acquired through diet. The ability to exploit toxins from external sources requires adaptations that prevent toxic effects on the consumer (autoresistance). Here, we examine genomic adaptations that could facilitate autoresistance to the diet‐acquired potent neurotoxic alkaloid batrachotoxin (BTX) in New Guinean toxic birds. Our work documents two new toxic bird species and shows that toxic birds carry multiple mutations in the SCN4A gene that are under positive selection. This gene encodes the most common vertebrate muscle Nav channel (Nav1.4). Molecular docking results indicate that some of the mutations that are present in the pore‐forming segment of the Nav channel, where BTX binds, could reduce its binding affinity. These mutations should therefore prevent the continuous opening of the sodium channels that BTX binding elicits, thereby preventing muscle paralysis and ultimately death. Although these mutations are different from those present in Neotropical Phyllobates poison dart frogs, they occur in the same segments of the Nav1.4 channel. Consequently, in addition to uncovering a greater diversity of toxic bird species than previously known, our work provides an intriguing example of molecular‐level convergent adaptations allowing frogs and birds to ingest and use the same neurotoxin. This suggests that genetically modified Nav1.4 channels represent a key adaptation to BTX tolerance and exploitation across vertebrates. see also the Perspective by Sophie Zaaijer and Simon C. Groen [ABSTRACT FROM AUTHOR]

Variable harlequin frogs Atelopus varius have declined significantly throughout their range as a result of infection with the fungal pathogen Batrachochytrium dendrobatidis (Bd). The Panama Amphibian Rescue and Conservation Project maintains an ex situ population of this Critically Endangered species. We conducted a release trial with surplus captive-bred A. varius individuals to improve our ability to monitor frog populations post-release, observe dispersal patterns after freeing them into the wild and learn about threats to released frogs, as well as to determine whether natural skin toxin defences of frogs could be restored inside mesocosms in the wild and to compare Bd dynamics in natural amphibian communities at the release site vs a non-release site. The 458 released frogs dispersed rapidly and were difficult to re-encounter unless they carried a radio transmitter. No frog was seen after 36 days following release. Thirty frogs were fitted with radio transmitters and only half were trackable by day 10. Tetrodotoxin was not detected in the skins of the frogs inside mesocosms for up to 79 days. Bd loads in other species present at sites were high prior to release and decreased over time in a pattern probably driven by weather. No differences were observed in Bd prevalence between the release and non-release sites. This trial showed that refinements of our methods and approaches are required to study captive Atelopus frogs released into wild conditions. We recommend continuing release trials of captive-bred frogs with post-release monitoring methods, using an adaptive management framework to advance the field of amphibian reintroduction ecology. [ABSTRACT FROM AUTHOR]

Changes in environmental temperature may induce variations in thermal tolerance and sensitivity in ectotherm organisms. These variations generate plastic responses that can be analyzed by examining their Thermal Performance Curves (TPCs). Additionally, some performance traits, like locomotion, could be affected by other factors such as biological interactions (e.g., predator–prey interaction). Here, we evaluate if the risk of predation modifies TPCs in Mendoza four‐eyed frog (Pleurodema nebulosum, Burmeister, 1861) and Guayapa's four‐eyed frog (Pleurodema guayapae, Barrio, 1964), two amphibian species that occur in ephemeral ponds in arid environments. We measured thermal tolerances and maximum swimming velocity at six different temperatures in tadpoles under three situations: control, exposure to predator chemical cues, and exposure to conspecific alarm cues. TPCs were fitted using General Additive Mixed Models. We found that curves of tadpoles at risk of predation differed from those of control mainly in thermal sensitivity parameters. Our work confirms the importance of biotic interactions have in thermal physiology. Research Highlights: Understanding how ectotherms respond to variations in environmental temperature is crucial for predicting their responses to ongoing warming. We found plasticity in thermal sensitivity and thermal tolerance as a response to predation risk. [ABSTRACT FROM AUTHOR]

With over 40% of species threatened with extinction, the distributional range of most amphibians is still unknown, generating uncertainty whether species are naturally rare, under‐sampled, or difficult to detect. We implemented a modelling approach that uses bromeliads as surrogates to predict the distribution of habitat specialist frogs that lack distributional data. We aimed to predict and survey potential new sites for the occurrence of a rare and microendemic bromeliad‐dwelling frog from the Atlantic Rainforest of Brazil. We used Maxent to predict suitable areas based on climate and topographic profiles, combined with 21 occurrence records of bromeliads within which our target frog species (Crossodactylodes itambe) is strictly restricted. The bromeliad‐based models identified four areas potentially suitable, and subsequent surveys revealed an entirely new species of a rare bromeliad‐dwelling frog in one of the areas. We demonstrate that using easy‐to‐survey surrogate species that have a strong relationship with species that are hard to detect has enormous potential to reveal crucial information on the potential ranges and distribution of cryptic taxa. Such a surrogate modelling approach could be extended to other habitat specialist species that lack distribution data, such as amphibians restricted to specific refugia and/or reproduction sites. This could improve the targeting of surveys and increase understanding of the patterns of rarity and the drivers of species distribution, especially for areas with high endemicity and range‐restricted frogs. [ABSTRACT FROM AUTHOR]

Invasive species threaten biodiversity globally. Amphibians are one of the most threatened vertebrate taxa and are particularly sensitive to invasive species, including other amphibians. African clawed frogs (Xenopus laevis) are native to Southern Africa but have subsequently become invasive on multiple continents—including multiple parts of North America—due to releases from the pet and biomedical trades. Despite their prevalence as a global invader, the impact of X. laevis remains understudied. This includes the Pacific Northwest of the USA, which now hosts multiple expanding X. laevis populations. For many amphibians, chemical cues communicate important information, including the presence of predators. Here, we tested the role chemical cues may play in mediating interactions between feral X. laevis and native amphibians in the Pacific Northwest. We tested whether native red-legged frog (Rana aurora) tadpoles display an antipredator response to non-native frog (X. laevis) or native newt (rough-skinned newts, Taricha granulosa) predator chemical stimuli. We found that R. aurora tadpoles exhibited pronounced anti-predator responses when exposed to chemical cues from T. granulosa but did not display anti-predator response to invasive X. laevis chemical cues. We also began experimentally testing whether T. granulosa—which produce a powerful neurotoxin tetrodotoxin (TTX)—may elicit an anti-predator response in X. laevis, that could serve to deter co-occupation. However, our short-duration experiments found that X. laevis were attracted to newt chemical stimuli rather than deterred. Our findings show that X. laevis likely poses a threat to native amphibians, and that these native species may also be particularly vulnerable to this invasive predator, compared to native predators, because toxic native newts may not limit X. laevis invasions. Our research provides some of the first indications that native Pacific Northwest species may be threatened by feral X. laevis and provides a foundation for future experiments testing potential management techniques for X. laevis. [ABSTRACT FROM AUTHOR]

Sexual selection can result in the evolution of extreme armaments and ornaments, and the development and maintenance of these traits can come at a considerable cost. These costs have been implicated in enforcing an upper limit on trait divergence and promoting condition-dependent traits, such that only individuals in sufficiently high condition can effectively wield these armaments and advertise these ornaments. Numerous studies demonstrate the condition-dependence of sexually selected traits, especially those used by males to advertise to females. In this study, we investigated condition-dependent mating calls in the túngara frog Physalaemus (= Engystomops) pustulosus. We manipulated male condition in the laboratory over a nine-day period by restricting food availability. We then documented: the relationship between male condition (the relative change in body mass from night 1 to night 9) and acoustic parameters of his mating call; how male condition influenced the male's responses to call playbacks; and finally, how male condition influenced the attractiveness of the male's calls to females. Males who were not fed during this period showed significant changes in call frequency, duration, and amplitude. In response to playbacks, unfed males called less, and made fewer complex calls. Finally, in phonotaxis experiments, females were more attracted to the calls of unfed males on night 1 to the calls of the same males on night 9. Fed males, on the other hand, showed no significant differences between nights 1 and 9 in call parameters, calling effort, and call attractiveness. This study shows the pervasive effects of condition on three aspects of sexual communication: signal parameters, behavioral response to vocal competition, and mating call attractiveness. Significance statement: This study shows the widespread effects that an animal's condition has on its communication system, including: influences on the acoustic parameters of the male's mating call, their calling effort, and the sexual attractiveness of mating calls to females. [ABSTRACT FROM AUTHOR]

Communication during parental care is important in the context of offspring defence and parent-offspring recognition. In aquatic environments, chemical communication is usually the most effective and plays different roles in parental behaviour in many groups of animals. Attending females of some Neotropical anurans (Leptodactylus) lead entire schools of tadpoles through the water. However, little is known about how attending females communicate with the tadpoles or whether this communication is mother-offspring specific. We therefore conducted behavioural experiments with Leptodactylus podicipinus to address these questions. Initially, we investigated how visual, tactile, and chemical stimuli from attending females affect the aggregation behaviour of tadpoles. Next, we compared the effects of the chemical stimulus from attending females with those from other conspecifics (non-attending females and males) on schooling behaviour. Finally, we tested whether tadpoles preferred to be aggregated next to familiar attending females instead of unfamiliar ones. Our results indicated that only the chemical stimulus from attending females, and not visual or tactile, increased the time that tadpoles remained aggregated. The chemical stimuli from non-attending females and males did not affect tadpoles' behaviour. However, contrary to our expectations, we did not find a school preference for familiar attending females. Our study is the first showing that chemical stimulus is important for mother-tadpole communication in a Leptodactylus species, playing a crucial role in tadpole aggregation and attraction. Future studies including other species should address the nature of the chemical compounds and their role, if any, in kin recognition in these frogs with aquatic maternal care. Significance statement: Parent-offspring communication is not well understood in anurans. Females of some frog species in the genus Leptodactylus protect and guide schools of tadpoles in aquatic habitats and tactile, chemical and visual communication may be involved. Through our experiments, we found that only chemical stimulus from attending females had a positive effect on tadpoles´ aggregation time and attraction, playing an important role in school cohesion. Additionally, there were no differences in tadpoles´ responses to chemical stimuli from familiar and unfamiliar females, which may increase tadpoles´ survival chances. In these cases, however, the costs and benefits for attending females and tadpoles are yet to be addressed. Although tactile and visual stimuli deserve more investigation, we showed that parent-offspring chemical communication in this frog species is effective, leading to school cohesion, consequently favouring protection of tadpoles by their mothers. [ABSTRACT FROM AUTHOR]

Background: Since the establishment of the Vu Quang National Park in 2002 in Ha Tinh Province, central Vietnam, several surveys on the amphibian fauna have been undertaken in this protected area. In 2009, Nguyen et al. provided a list of 23 amphibian species from Vu Quang National Park. In addition, a new species was described in 2021 from the National Park, namely Vietnamophryne vuquangensis. New information: As a result of our field surveys in 2013 and 2023, a total of 29 species of amphibians was recorded from the Vu Quang National Park. Six of them are recorded for the first time from Ha Tinh Province, comprising three species of Megophryidae, one species of Dicroglossidae, one species of Ranidae and one species of Rhacophoridae. In addition, we provide morphological data and ecological notes on the aforementioned species. [ABSTRACT FROM AUTHOR]

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Background: Esculentin-1, initially discovered in the skin secretions of pool frogs (Pelophylax lessonae), has demonstrated broad-spectrum antimicrobial activity; however, its immunomodulatory properties have received little attention. Results: In the present study, esculentin-1 cDNA was identified by analysing the skin transcriptome of the dark-spotted frog (Pelophylax nigromaculatus). Esculentin-1 from this species (esculentin-1PN) encompasses a signal peptide, an acidic spacer peptide, and a mature peptide. Sequence alignments with other amphibian esculentins-1 demonstrated conservation of the peptide, and phylogenetic tree analysis revealed its closest genetic affinity to esculentin-1P, derived from the Fukien gold-striped pond frog (Pelophylax fukienensis). Esculentin-1PN transcripts were observed in various tissues, with the skin exhibiting the highest mRNA levels. Synthetic esculentin-1PN demonstrated antibacterial activity against various pathogens, and esculentin-1PN exhibited bactericidal activity by disrupting cell membrane integrity and hydrolyzing genomic DNA. Esculentin-1PN did not stimulate chemotaxis in RAW264.7, a murine leukemic monocyte/macrophage cell line. However, it amplified the respiratory burst and augmented the pro-inflammatory cytokine gene (TNF-α and IL-1β) expression in RAW264.7 cells. Conclusions: This novel finding highlights the immunomodulatory activity of esculentin-1PN on immune cells. [ABSTRACT FROM AUTHOR]

Species identification plays a significant role in biodiversity conservation. As many species remain unrecognized, particularly in neotropical hotspots like the Brazilian Atlantic Forest (AF), novel molecular techniques are being widely employed to bridge this gap. In this study, we used DNA barcoding and phylogenetic tools to identify a new population of Sphaenorynchus canga in the central region of the Brazilian AF. Our results extend the species' known distribution by approximately 200 km to the south, encompassing a different mountain range than its type locality (Serra do Espinhaço). This disjunct distribution, while not uncommon among amphibians, suggests a historical connection between these two mountain complexes as a biogeographic explanation. Despite the discovery of a new S. canga population, the species continues to face numerous anthropogenic threats such as mining, land use, and cattle ranching. Urgent conservation and research efforts are warranted to ensure the survival of S. canga populations across these habitats. [ABSTRACT FROM AUTHOR]

We report the first mitochondrial genomes of the Afrobatrachian frog species Hyperolius substriatus, providing insights into the gene arrangements, duplications, and evolutionary dynamics within this taxonomically complex genus. Assemblies were gained from two museum specimens and included all 37 typical vertebrate mitogenomic genes. In both cases, the mitogenome of H. substriatus shows duplications of tRNAs (trnL, trnT and trnP). The WANCY region exhibits the characteristic Afrobatrachian pattern but with unique intergenic spacers. Both copies of duplicated non-coding and control regions show high sequence similarity within and between specimens. The distinct gene order and homology of duplications observed can be explained under the tandem duplication and random loss model of mitochondrial evolution. Furthermore, a comparison with Hyperolius marmoratus highlights differences in gene copy number and synteny, and the presence of a duplication of trnM in the latter appears to be a derived condition. Together, these findings provide valuable insights into the taxonomy and evolution of Hyperolius, contributing to understanding interspecific gene reorganisation in this diverse group and suggesting that gene arrangements could help resolve some of the taxonomic problems of this complex genus. [ABSTRACT FROM AUTHOR]

This essay argues for design as an expression of analytic rigour and ethical commitment. It explores what it might mean to 'write' in collaboration with the entities and forces from Country, ancestors, oceans, soil, honeyeaters, sound, wild bores, frogs, fire, ash, sand, trees, and echoes, to colour, code, bitrates, cameras, computers, and archives. Every design decision in 'Epistemic attunements' was conceptually‐motivated and informed by an anthropologically‐attuned sensibilty. It was never simply a case of making things look 'beautiful'. The analytic force of the design propelled our intermedial arguments forward, but also sideways, down through layers, into shifts of sensation and abrupt moments of pause for specific critical effect. [ABSTRACT FROM AUTHOR]

Frostius pernambucensis is a phytotelm-breeding frog with endotrophic larvae. Although the larvae were formally described, no aspect of its internal morphology is known. In this paper, we re-describe the tadpole based on a large sample, describe its internal anatomy (buccopharyngeal cavity and musculo-skeletal system), provide data on natural history, and discuss the evolution of endotrophy and phytotelma colonization. The tadpoles of F. pernambucensis are highly modified, with depressed bodies, reduced mouthparts, and long tails. Many character-states described for these tadpoles can be related to its endotrophic development. Consequence of this highly modified phenotype, we propose several novel putative synapomorphies for the genus: (1) labial tooth row formula 1/1; (2) absence of pustulation in the buccal roof and (3) floor; (4) absence of median ridge; (5) absence of lateral ridge papillae; (6) absence of secretory ridges and pores; (7) absence of filter plates; (7) m. subarcualis rectus II–IV originating on ceratobranchial III; (8) m. subarcualis rectus II–IV inserting on ceratobranchial I; (8) ventral slip of the m. subarcualis rectus I inserting on the ceratobranchial III; (9) suprarostral corpora fused to the cornua trabeculae; (10) commissura quadratoorbitalis absent; (11) cerabranchial II attached to the planum hypobranchiale; and (12) ceratobranchial III attached to the planum hypobranchiale. Finally, we also propose that the presence of a single pair of infralabial papilla could represent a synapomorphy of bufonids. The colonization of phytotelma seem to have created a selective pression on the development of F. pernambucenis, favoring the evolution of endotrophy. [ABSTRACT FROM AUTHOR]

Three photoperiods designed as 24L:0D; 0L:24D and 12L:12D were used to culture Hoplobatrachus occipitalis (Günther 1858) tadpoles to evaluate the growth performance and survival rate. One hundred and eighty tadpoles were distributed into the three photoperiodic ponds for 20 weeks and fed with duck weed. The frogs reared using the 0L:24D photoperiod had significantly higher growth performance, survival rate and metamorphosis where the tadpoles reached full metamorphosis after 20 weeks, than the other two photoperiods (P <.05.) Full metamorphosis of the tadpoles was seen when the limbs have been fully formed, tails and gills have been completely absorbed, the eyes become bulgy and they are completely out of water breathing by their lungs. Higher growth performance, survival rate and metamorphosis in 0L:24D photoperiod could be attributed to complete utilization of food, low ammonia concentration and high dissolved oxygen. Commercial aquaculture of H. occipitalis tadpoles should be done in 0L:24D to obtain complete metamorphosis, survival and faster growth in less time. Using 0L:24D to culture the tadpoles and releasing them into the wild will decrease overexploitation of the species, thereby aiding in their conservation. [ABSTRACT FROM AUTHOR]

Many methods commonly used to characterize ultrafast laser pulses, such as the frequency-resolved optical gating (FROG) or the dispersion scan (d-scan), face problems when they are used on pulses with a spectrum or phase varying within the laser beam cross section or the acquisition time. The presence of such pulse shape variation leads to discrepancy between the measured FROG trace and its reconstructed counterparts. Nevertheless, it is difficult to reliably discern this shape variation because even the distorted experimental FROG trace can be reasonably reproduced by a realistic pulse shape. In this work, we examine and discern the variation of the pulse shape based on a new method, dispersion-scan FROG (D-FROG), which combines the idea of dispersion scanning with the FROG method. This technique provides a means of careful evaluation of the laser pulse based on a set of FROG traces connected by known dispersion changes. Therefore, this method can disclose seemingly correct pulse retrievals from distorted datasets. The D-FROG method can be used as a simple extension of the FROG technique to provide a consistency check able to identify the shortcomings in the pulse characterization. [ABSTRACT FROM AUTHOR]

African-clawed frogs (Xenopus laevis) are invasive to many aquatic ecosystems across the globe worldwide. For an accurate and efficient determination of their distribution, the use of environmental DNA (eDNA) could facilitate broad surveys rooted simply in the collection of water samples from inhabited water bodies. Therefore, in this study, using species-specific primers, an eDNA method was developed to evaluate the distribution of African-clawed frogs in Japan. This newly developed method was tested in ponds in Wakayama Prefecture, Japan, and compared with conventional cage trap surveys. Overall, we successfully developed the abovementioned eDNA method and it was shown to be as effective as the conventional capture-related technique. [ABSTRACT FROM AUTHOR]

The damage of the frog rail significantly affects the wear of the crossing rail and restricts the passing speed of the train. A geometric 3D modeling of the vehicle passing through the crossing center is particularly concerned with the cumulative wheel-rail contact of the traffic volume. The frog rail wear is simulated to obtain the dynamic change of the impact force of the wheel on the frog rail as the rail wears. By summarizing the existing experimental results of other scholars, it is clear that the important factors, that cause the damage of the frog rail, are vehicle load, friction coefficient, slip roll ratio and shear stress. This paper combines the theoretical analysis of mechanics and 3D simulation to obtain the position change of the wheel-rail contact point with the wear of the frog rail, and finally compares it with the actual measurement results. It can more accurately predict the area where the maximum damage occurs after a certain amount of traffic for a certain fixed model, the change of wheel-rail contact point at frog rail is simulated with the wear of each component. Through theoretical analysis, the main factors determining frog rail damage were determined. Then evaluate the possible damage area of the frog track and control the prediction range to 5-10 cm, which reduces the detection time and cost. The worst state of distraction will be detected in time to facilitate replacement or polishing. Through further research in this area, the service life of the frog rail can be predicted. [ABSTRACT FROM AUTHOR]

Mountain ranges are hotspots of biodiversity. However, the mechanisms that generate biodiversity patterns in different mountainous regions and taxa are not apparent. The Western Ghats (WG) escarpment in India is a globally recognized biodiversity hotspot with high species richness and endemism. Most studies have either invoked paleoclimatic conditions or climatic stability in the southern WG refugium to explain this high diversity and endemism. However, the factors driving macroevolutionary change remain unexplored for most taxa. Here, we generated the most comprehensive dated phylogeny to date for ranoid frogs in the WG and tested the role of paleoclimatic events or climatic stability in influencing frog diversification. We found that the diversity of different ranoid frog clades in the WG either accumulated at a constant rate through time or underwent a decrease in speciation rates around 3–2.5 Ma during the Pleistocene glaciation cycles. We also find no significant difference in diversification rate estimates across elevational gradients and the three broad biogeographic zones in the WG (northern, central, and southern WG). However, time-for-speciation explained regional species richness within clades, wherein older lineages have more extant species diversity. Overall, we find that global paleoclimatic events have had little impact on WG frog diversification throughout most of its early history until the Quaternary and that the WG may have been climatically stable allowing lineages to accumulate and persist over evolutionary time. [ABSTRACT FROM AUTHOR]

Vocal communication plays an important role in survival, reproduction, and animal social association. Birds and mammals produce complex vocal sequence to convey context-dependent information. Vocalizations are conspicuous features of the behavior of most anuran species (frogs and toads), and males usually alter their calling strategies according to ecological context to improve the attractiveness/competitiveness. However, very few studies have focused on the variation of vocal sequence in anurans. In the present study, we used both conventional method and network analysis to investigate the context-dependent vocal repertoire, vocal sequence, and call network structure in serrate-legged small treefrogs Kurixalus odontotarsus. We found that male K. odontotarsus modified their vocal sequence by switching to different call types and increasing repertoire size in the presence of a competitive rival. Specifically, compared with before and after the playback of advertisement calls, males emitted fewer advertisement calls, but more aggressive calls, encounter calls, and compound calls during the playback period. Network analysis revealed that the mean degree, mean closeness, and mean betweenness of the call networks significantly decreased during the playback period, which resulted in lower connectivity. In addition, the increased proportion of one-way motifs and average path length also indicated that the connectivity of the call network decreased in competitive context. However, the vocal sequence of K. odontotarsus did not display a clear small-world network structure, regardless of context. Our study presents a paradigm to apply network analysis to vocal sequence in anurans and has important implications for understanding the evolution and function of sequence patterns. [ABSTRACT FROM AUTHOR]

In skeletal muscle, the Ca2+ release flux elicited by a voltage clamp pulse rises to an early peak that inactivates rapidly to a much lower steady level. Using a double pulse protocol the fast inactivation follows an arithmetic rule: if the conditioning depolarization is less than or equal to the test depolarization, then decay (peak minus steady level) in the conditioning release is approximately equal to suppression (unconditioned minus conditioned peak) of the test release. This is due to quantal activation by voltage, analogous to the quantal activation of IP3 receptor channels. Two mechanisms are possible. One is the existence of subsets of channels with different sensitivities to voltage. The other is that the clusters of Ca2+-gated Ryanodine Receptor (RyR) β in the parajunctional terminal cisternae might constitute the quantal units. These Ca2+-gated channels are activated by the release of Ca2+ through the voltage-gated RyR α channels. If the RyR β were at the basis of quantal release, it should be modified by strong inhibition of the primary voltage-gated release. This was attained in two ways, by sarcoplasmic reticulum (SR) Ca2+ depletion and by voltage-dependent inactivation. Both procedures reduced global Ca2+ release flux, but SR Ca2+ depletion reduced the single RyR current as well. The effect of both interventions on the quantal properties of Ca2+ release in frog skeletal muscle fibers were studied under voltage clamp. The quantal properties of release were preserved regardless of the inhibitory maneuver applied. These findings put a limit on the role of the Ca2+-activated component of release in generating quantal activation. [ABSTRACT FROM AUTHOR]

Cytogenetics can be used as a tool to study the evolution of polyploidy and taxonomy. Here we focus on aquatic African pipids, dwarf clawed frogs (Hymenochirus). Our study reveals that dwarf clawed frogs, present for decades in captivity, are best referred to as Hymenochirus sp. instead of the commonly used name ' H. boettgeri ' or sometimes ' H. curtipes '. We present the first karyotype from a morphologically identified specimen of H. boettgeri with a known locality in the north-western Congo, which is tetraploid with 2n = 36. The captive Hymenochirus species has been found diploid in previous studies with different reported chromosome numbers; here we reveal 2n = 20A + 1B chromosomes. Our findings suggest that the tetraploid H. boettgeri karyotype evolved through fusion of two biarmed chromosomes and subsequent allotetraploidization, and is functionally diploid, similar to the origin of tetraploid clawed frogs in the subgenus Xenopus. We observed the stable presence of a single B chromosome in both sexes of our individuals from the captive population of Hymenochirus sp. However, additional investigation is necessary to clarify whether there is variation in the number of A and B chromosomes among populations, individuals, and/or tissues. Further research is also needed to understand the evolution and taxonomy of the genus Hymenochirus. [ABSTRACT FROM AUTHOR]

Many native insects have evolved defenses against native predators. However, their defenses may not protect them from non-native predators due to a limited shared history. The American bullfrog, Aquarana catesbeiana (Anura: Ranidae), which has been intentionally introduced to many countries, is believed to impact native aquatic animals through direct predation. Adults of whirligig beetles (Coleoptera: Gyrinidae), known for swimming and foraging on the water surface of ponds and streams, reportedly possess chemical defenses against aquatic predators, such as fish. Although whirligig beetles potentially encounter both bullfrogs and other frogs in ponds and lakes, the effectiveness of their defenses against frogs has been rarely studied. To assess whether whirligig beetles can defend against native and non-native frogs, we observed the behavioral responses of the native pond frog, Pelophylax nigromaculatus (Anura: Ranidae), and the invasive non-native bullfrog, A. catesbeiana, to native whirligig beetles, Gyrinus japonicus and Dineutus orientalis, in Japan. Adults of whirligig beetles were provided to frogs under laboratory conditions. Forty percent of G. japonicus and D.orientalis were rejected by P. nigromaculatus, while all whirligig beetles were easily consumed by A. catesbeiana. Chemical and other secondary defenses ofG. japonicus and D. orientalis were effective for some individuals of P. nigromaculatus but not for any individuals of A. catesbeiana. These results suggest that native whirligig beetles suffer predation by invasive non-native bullfrogs in local ponds and lakes in Japan. [ABSTRACT FROM AUTHOR]

Visual systems adapt to different light environments through several avenues including optical changes to the eye and neurological changes in how light signals are processed and interpreted. Spectral sensitivity can evolve via changes to visual pigments housed in the retinal photoreceptors through gene duplication and loss, differential and coexpression, and sequence evolution. Frogs provide an excellent, yet understudied, system for visual evolution research due to their diversity of ecologies (including biphasic aquatic-terrestrial life cycles) that we hypothesize imposed different selective pressures leading to adaptive evolution of the visual system, notably the opsins that encode the protein component of the visual pigments responsible for the first step in visual perception. Here, we analyze the diversity and evolution of visual opsin genes from 93 new eye transcriptomes plus published data for a combined dataset spanning 122 frog species and 34 families. We find that most species express the four visual opsins previously identified in frogs but show evidence for gene loss in two lineages. Further, we present evidence of positive selection in three opsins and shifts in selective pressures associated with differences in habitat and life history, but not activity pattern. We identify substantial novel variation in the visual opsins and, using microspectrophotometry, find highly variable spectral sensitivities, expanding known ranges for all frog visual pigments. Mutations at spectral-tuning sites only partially account for this variation, suggesting that frogs have used tuning pathways that are unique among vertebrates. These results support the hypothesis of adaptive evolution in photoreceptor physiology across the frog tree of life in response to varying environmental and ecological factors and further our growing understanding of vertebrate visual evolution. [ABSTRACT FROM AUTHOR]

Hydrological alteration has contributed to the global decline of stream frogs. Flows support stream frog reproduction, juvenile development, food resources, and maintain habitats for all life stages. At present, there is a lack of information regarding the specific water requirements necessary for the conservation of stream frogs. To address this gap, we developed a traits‐based approach that serves as a valuable tool for grouping and prioritising water‐dependent stream frog species to inform future research priorities and environmental flow design. In this study, we focussed on 53 Australian frog species and analysed eight species traits to develop water‐dependent functional groups for stream frogs. We classified frogs based on their level of water dependency using an agglomerative hierarchical clustering analysis and a systematic review of water requirements and water management threats. The distinguishing traits that determined functional groups were: tadpole body type, egg clutch type, stream breeding habitat type, and documented association with flowing water and water permanence. Our study identified two distinct water‐dependent groups: facultative stream spawners, capable of reproducing in both stream and non‐stream habitats, and obligate stream spawners, restricted solely to stream habitats. Importantly, we highlight that the obligate stream spawners are the most sensitive group to within‐channel flow alteration and should be prioritised for water management decisions in lotic environments. This study represents the first comprehensive overview of the importance of hydrology for stream frogs and identifies the critical need for additional research and validation to enhance our understanding of stream frog responses to flows regimes. [ABSTRACT FROM AUTHOR]

Intraspecific variation in body size, both among populations and between sexes, is an important factor influencing life-history strategies. This variation might be the response to different environmental conditions, as well as natural and sexual selection, and can result in differences in behavior and reproductive strategies among populations. Here, we use the dyeing poison frog (Dendrobates tinctorius) as a model to investigate how interpopulation variation in body size and sexual size dimorphism affects reproductive strategies. As body size increased, sexual size dimorphism also increased, i.e., females were larger than males, and more so in populations with overall larger frogs. This indicates that there is a stronger selection for body size in females than in males, likely as a response to divergent reproductive investment between the sexes. Females from larger-bodied populations produced larger clutches, but the overall number of froglets produced per clutch did not differ among populations. We discuss potential causes and mechanisms that might be responsible for the observed divergence in body size, sexual size dimorphism, and reproductive strategies among populations that likely represent local adaptations. Our findings demonstrate the importance of cross-population studies, cautioning against drawing general conclusions about a species' ecology without accounting for intraspecific variation. [ABSTRACT FROM AUTHOR]

Parents often have the opportunity to invest in offspring that offer different returns, with such variation arising from factors intrinsic to the offspring itself (e.g., body condition) or extrinsic (e.g., food availability in the environment). To identify the best targets for investment, parents may directly assess the environment or their offspring, but often also rely on offspring-generated signals when making investment decisions. We first used captive breeding pairs of the poison frog Ranitomeya imitator, a frog that facultatively feeds its young, to experimentally test how parents respond to variation in exogenous food availability in nurseries. We then used two experiments to test the prediction that, as is the case in many animals, the begging display of R. imitator tadpoles contains information about long- and short-term food intake. Parents rearing multiple tadpoles were more likely to feed and fed more to their tadpoles in control nurseries than to those in nurseries we supplemented. However, these control tadpoles completed metamorphosis at a smaller size. Tadpoles hand-reared on diets that drove differences in tadpole size did not differ in their begging at any point during development. Similarly, begging did not differ when tadpoles were food-deprived or fed. While parent R. imitator appear to invest strategically, begging seems unlikely to be parents' source of information, at least about the size and development of their tadpoles. Parental favoritism and offspring begging have evolved in diverse lineages, and studies of animals that differ in their life-histories can continue to offer insights into how and why offspring-parent communication evolves. [ABSTRACT FROM AUTHOR]

Aposematic animals are chemically defended and tend to have bright and conspicuous color patterns that warn predators of the costs of attack. Most research on aposematism focuses on the role that predator cognition has on the evolution of aposematic defenses. Although the behavior of aposematic organisms is likely to be crucial in affecting their survival, it has been less thoroughly investigated. Bolder and more active movement decisions, and a reduced likelihood to respond to perceived threats of predation, should increase the conspicuousness and distinctiveness of aposematic prey to predators, which in turn should enhance their fitness. Here, we developed a laboratory-based framework to study the behavior of poison frogs, which are both conspicuously colored and defended by toxic alkaloids. We designed experiments to quantify boldness, exploratory behavior, movement patterns, and escape behavior (flight initiation distance from an incoming avian predator model) in the strawberry poison frog, Oophaga pumilio, from northeastern Costa Rica. We tested females, non-vocalizing males, and calling males to measure the intraspecific variability in their behavior. Calling males had a larger flight initiation distance than females, and varied more in directional change when moving compared to females. Non-vocalizing males varied more in sinuosity when moving compared to females. We found no differences in boldness or exploratory behavior between the three groups. Our results indicate movement variability within intraspecific groups of a single population in O. pumilio. Additionally, our results suggest plasticity in the escape behavior of calling males, which contrasts with findings from field-based studies. Our framework allowed us to quantify intraspecific differences in some anti-predator behaviors. Combining individual behavioral profiles with field data can provide a standardized comparative approach to understand the ecological and evolutionary consequences of anti-predator behavior within and among species of poison frogs (Abstract in Spanish in the Online Appendix 1). [ABSTRACT FROM AUTHOR]

Many animal lineages produce and provision offspring with nutritive material such as milk, lipid-enriched skin, or mucus. Some frogs deposit offspring into small pools of water known as phytotelmata, and a subset of those species also provision offspring with eggs. Often when parental frogs enter the water, oophagous tadpoles swim erratically, vibrate, nip, and even suck on adult skin, which has traditionally been interpreted as begging and tactile stimulus for oviposition. However, these behaviors are also consistent with the hypothesis that such mouth-to-skin contact serves the function of acquiring secretory provisioning from parents, as in the mucophagous fry of some fishes. Here we present images obtained with a macro lens at 6 K resolution of mother-offspring interactions in the strawberry poison frog, Oophaga pumilio, that suggest that tadpoles not only poke or nip maternal skin during feeding visits, but rather forcefully suck on it. We compare these observations to those from numerous lower resolution videos of previous experiments with O. pumilio, and place the findings in the context of a literature review of both anecdotal evidence of mother-tadpole interactions across phytotelm-breeding anurans and secretory provisioning across the animal kingdom. We propose that (1) skin sucking behavior may involve the transfer of nutritive mucous secretions or other defensive, immunological, hormonal, or microbial factors from mother frogs to tadpoles and that (2) such secretions may serve to supplement egg provisioning in this and other frogs with oophagous and phytotelm-dwelling larvae. [ABSTRACT FROM AUTHOR]

To combat the loss of species due to emerging infectious diseases, scientists must incorporate ecological parameters, such as temperature and humidity, to understand how the environment affects host–pathogen interactions. The fungal disease chytridiomycosis is a compelling case study to investigate the role of both temperature and humidity on infectious disease, as both the fungal pathogen (Batrachochytrium dendrobatidis, Bd) and the host (amphibians) are heavily influenced by these abiotic factors. We performed two experiments to investigate the importance of relative humidity and temperature on frog immunity (production of antimicrobial skin secretions) and disease development in captive golden frogs (Atelopus zeteki) of Panama. We found that the quantity of skin secretions significantly decreased over time in frogs moved from low to medium and high relative humidity treatments. Following Bd exposure, frogs in high temperature (26–27 °C) and high relative humidity (80–90%) had lower pathogen loads and survived significantly longer than frogs kept in all other treatment conditions, including high temperature and low relative humidity. These results suggest that high relative humidity may be an important, although less understood, mediator of Bd infection and the survival of golden frogs. Because the environment can drastically alter disease dynamics, understanding how temperature and humidity influence chytridiomycosis outcomes in golden frogs may be essential for the success of the reintroduction of captive frogs. [ABSTRACT FROM AUTHOR]

Abstract Puerto Rico harbors a diverse vertebrate fauna with high levels of endemism. However, while several books for vertebrate diversity and local checklists for birds have been published, checklists of amphibians, reptiles, and bats are lacking or nonexistent at both local and regional scales. In this study, we documented the amphibian, reptile, and bat faunas at Mata de Plátano Field Station and Nature Reserve, in Arecibo, Puerto Rico. We document four species of amphibians, seven lizards, three snakes, and nine bats. Despite prior works using samples from this nature reserve, this represents the first vertebrate checklist for the Mata de Plátano Field Station and Nature Reserve. We provide additional natural history observations based on our survey results and highlight the importance of including local and regional checklists of species for downstream research and conservation.

Transparent immunodeficient animal models not only enhance in vivo imaging investigations of visceral organ development but also facilitate in vivo tracking of transplanted tumor cells. However, at present, transparent and immunodeficient animal models are confined to zebrafish, presenting substantial challenges for real-time, in vivo imaging studies addressing specific biological inquiries. Here, we employed a mitf−/−/prkdc−/−/il2rg−/− triple-knockout strategy to establish a colorless and immunodeficient amphibian model of Xenopus tropicalis. By disrupting the mitf gene, we observed the loss of melanophores, xanthophores, and granular glands in Xenopus tropicalis. Through the endogenous mitf promoter to drive BRAFV600E expression, we confirmed mitf expression in melanophores, xanthophores and granular glands. Moreover, the reconstruction of the disrupted site effectively reinstated melanophores, xanthophores, and granular glands, further highlighting the crucial role of mitf as a regulator in their development. By crossing mitf−/− frogs with prkdc−/−/il2rg−/− frogs, we generated a mitf−/−/prkdc−/−/il2rg−/−Xenopus tropicalis line, providing a colorless and immunodeficient amphibian model. Utilizing this model, we successfully observed intravital metastases of allotransplanted xanthophoromas and migrations of allotransplanted melanomas. Overall, colorless and immunodeficient Xenopus tropicalis holds great promise as a valuable platform for tumorous and developmental biology research. Xenopus tropicalis with triple knockout of mitf, prkdc, and il2rg is a colorless immunodeficient animal model. The mitf−/− frog further underscores the vital role of the mitf in the development of melanophores, xanthophores, and granular glands. [ABSTRACT FROM AUTHOR]

Elizabethkingia miricola (E. miricola) is a significant pathogen that causes the crooked head disease in black spotted frogs. This disease has plagued numerous frog farms in China and has resulted in substantial losses to the frog farming industry. Nonetheless, the exact mechanism that causes the disease in frogs remains unknown. In this study, transcriptomic and microbiomic analyses were conducted to analyze frog samples infected with E. miricola to reveal the infection mechanism of the pathogen. Liver transcriptomic analysis indicated that the livers of infected frogs had 1469 differentially expressed genes when compared with an uninfected group. These DEGs are mainly involved in immunity and metabolism, including neutrophil extracellular trap formation, the NOD-like receptor signaling pathway, leukocyte transendothelial migration, chemokine signaling pathway, Fc gamma R-mediated phagocytosis, and "metabolism"-related pathways such as the pentose phosphate pathway, carbon metabolism, glycerophospholipid metabolism, and glycerolipid metabolism. Similarly, 4737 DEGs were found in the kidney of infected frogs. These DEGs are mainly involved in immunity, including neutrophil extracellular trap formation, the NOD-like receptor signaling pathway, B cell receptor signaling pathway, C-type lectin receptor signaling pathway, complement and coagulation cascade, and Toll-like receptor signaling pathway. Ten immune-associated DEGs were screened in liver and kidney DEGs, respectively. And it was hypothesized that E. miricola infection could influence the host immune response. Microbiome analysis results showed that some opportunistic pathogens such as Citrobacter, Shigella, and Providencia were significantly elevated (p < 0.05) in infected frogs. Additionally, functional prediction confirmed that most of the microbiota in infected frogs were linked to metabolism-related KEGG pathways. In this study, the screened genes linked to immunity showed an association with the gut microbiome. The majority of these genes were found to be linked with the abundance of opportunistic pathogens. The results showed that E. miricola infection led to the downregulation of immune and metabolic-related genes, which led to the inhibition of immune function and metabolic disorder, and then increased the abundance of opportunistic pathogens in the gut microbiota. The findings of this study offer a preliminary foundation for comprehending the pathogenic processes of E. miricola infection in black spotted frogs. [ABSTRACT FROM AUTHOR]