Search Results (873)

Effective recognition of potential threats is crucial for survival in aquatic habitats, especially for amphibian larvae. As a critically endangered species, understanding how the Chinhai spiny newt (Echinotriton chinhaiensis) larvae recognize novel predators provides key scientific support for developing targeted conservation strategies. Using the American bullfrog (Lithobates catesbeiana) as a representative predator, we examined larval responses by presenting isolated visual or chemical cues, as well as visual cues from predators of differing body sizes. We measured larval avoidance and activity. Results showed that with only visual cues, larvae quickly avoided the bullfrog and significantly reduced their activity compared to controls. With only chemical cues, activity decreased significantly, but avoidance behavior did not. When both large and small bullfrogs were present, larvae avoided the larger individual significantly more. These findings demonstrate that E. chinhaiensis larvae can use visual or chemical cues to detect novel potential predators and assess risk based on size to guide their avoidance behavior. This study provides key empirical data for understanding anti-predator responses in endangered caudate amphibians and informs conservation strategies against potential threats. Full article

In this study, we investigate the Suvarṇabhūmi area, corresponding to central–southern Mainland Southeast Asia. We test the hypothesis that this region, located to the south of the Himalayan foothills, can be characterised as a convergence zone in which diverse entities involving humans, animals, and artefacts have significantly diverged from their related counterparts outside the area. We argue that this process of convergence was facilitated by the Maritime Silk Road trade networks, which were particularly active between the 3rd century BCE and the 9th century CE. Comparative data are derived from multiple scientific disciplines, including linguistic typology, onomastics, epigraphy, archaeology, and evolutionary biology. This includes typological features of language, toponyms, inscriptions, glass bead chemistry and related material culture, and phylogenetic data from patterns of endemism to illustrate parallel convergence scenarios observed for each data type. The results reveal recurring patterns of convergence. Linguistic, technological, and biological entities tend to diverge from their original forms and realign with predominant regional types when entering the Suvarṇabhūmi area. The spread of Indic and Sinitic linguistic and cultural elements, the adaptation and development of Brāhmī scripts into distinct local forms, the secondary manufacturing of glass beads, and unique genetic lineages in mammals, amphibians, reptiles, fish, and plants all point to the region’s role as a dynamic interaction sphere. We argue that Suvarṇabhūmi functions as an ecological system, in which trajectories of convergence are notable across a number of individual aspects of cultural and biological diversity. Altogether, these components have contributed to shaping the region’s distinctive natural and cultural history. Full article

The review deals with the current knowledge on the global panzootic spread of highly pathogenic avian influenza viruses (HPAIVs), with an emphasis on the H5N1 clade 2.3.4.4b virus. It describes the viral structure, replication, pathotypes and molecular determinants of host range, including sialic-acid receptor usage and key genetic mammalian-adaptation markers (PB2-E627K and PB2-D701N mutations). The host spectrum nowadays extends from wild waterfowl and poultry including seabirds, terrestrial and marine mammals and, based largely on experimental studies or molecular detection, reptiles, amphibians, and fish. Recently, the H5N1 clade 2.3.4.4b virus has shown marked tropism for lactating mammary epithelium in dairy cattle, with virions shed in raw milk. The review reports epidemiology, geographical expansion, clinical presentation, pathogenesis and pathology, diagnosis, immune responses and vaccination approaches across species. It also analyses European Union (EU) and Italian regulatory frameworks, surveillance strategies and biosecurity measures from a One-Health perspective. The review highlights how climate change, wildlife–livestock interfaces, intensive farming and global trade favor viral persistence and genomic reassortment and concludes by stressing strategic actions to limit further host adaptation and panzootic/pandemic risks. Full article

Amphibians, as sensitive bioindicators, reflect environmental health issues that also impact human communities through shared pathways, including contaminated water and agricultural products. This perspective addresses the need to standardize the reporting of anomalies (defined as significant phenotypic deviations from typical morphology, structure, or coloration) in amphibians in Mexico, where inconsistent terminology and incomplete data limit their utility for environmental monitoring. We propose a framework that includes a classification of anomalies (structural and chromatic) and a field-based physical examination protocol to systematically document these cases. The approach integrates detailed guidelines to ensure comprehensive reporting and data comparability, addressing geographic and taxonomic biases. Recent findings highlight that over 50% of anomaly reports in Mexico are incidental, with predominant cases in Ambystomatidae, Hylidae, and Ranidae, and linked to anthropogenic pressures such as agrochemicals. The framework promotes interdisciplinary collaboration, citizen science, and emerging technologies like artificial intelligence for sustainable monitoring. By standardizing the detection and reporting of anomalies, this proposal strengthens the role of amphibians as sentinels of ecosystem health, with applications in Mexico and other regions facing high environmental degradation. Full article

Amphibians are among the most threatened vertebrate groups globally, with over 40% of species at risk of extinction. However, a gap remains in understanding how to effectively develop and implement amphibian conservation strategies at local and global scales to minimize extinction risk. This review synthesizes multidisciplinary evidence to frame amphibian conservation as a priority not only for species preservation but for safeguarding ecosystem functioning and human well-being. Drawing on ecological, physiological, biomedical, and technological literature, we highlight the foundational roles amphibians play in various biomes: regulating invertebrate populations, mediating nutrient and energy flows, modifying physical habitats, and supporting biodiversity through trophic interactions. Their dual aquatic–terrestrial life cycles and highly permeable skin make them highly sensitive to environmental change, positioning them as bioindicators for ecosystem health. We further explore emerging tools and concepts such as environmental metabolomics, remote sensing, and citizen science for monitoring population trends and environmental stressors. Additionally, we discuss conservation challenges in relation to land-use change, climate disruption, invasive species, emerging diseases, and institutional underinvestment. We argue for the recognition of amphibians as ecological allies and the increased integration of amphibian conservation into broader frameworks such as ecosystem service valuation, climate resilience planning, and public health policy improvement. Finally, we identify key research gaps and suggest future directions to remedy these oversights, including the incorporation of traditional knowledge, socio-cultural engagement, and technological innovations for sustainable amphibian conservation. Realizing this vision will require globally coordinated, locally grounded strategies that fuse scientific insight, inclusive governance, and long-term investment—ensuring that amphibian conservation advances ecosystem stability and benefits both nature and society. Full article

Climate change poses a serious threat to amphibians and reptiles, which are especially vulnerable because of limited thermoregulatory capacity and restricted dispersal. We used an ensemble species distribution modeling framework to assess habitat determinants, niche breadth, and climate-driven distribution changes for eight legally protected endangered amphibian and reptile species in South Korea. Occurrence records collected between 1997 and 2021 were combined with ten bioclimatic, topographic, and hydrological predictors, and 11 species distribution modeling algorithms (SDMs), including Random Forest and MaxEnt, were implemented and combined into weighted ensemble predictions. The weighted ensemble model showed high predictive performance (mean ROC–AUC = 0.897; overall mean across all SDMs = 0.843). Variable-importance analysis revealed clear taxonomic contrasts: reptiles exhibited approximately 1.7-fold greater dependence on temperature variables than amphibians, whereas amphibians were more strongly associated with precipitation and topographic context. Environmental niche-breadth analysis identified Sibynophis chinensis, Hynobius yangi, and Dryophytes suweonensis as narrow- or moderate-niche specialists largely constrained by precipitation of the driest month and a small set of climatic variables. Under moderate (SSP2-4.5) and high (SSP5-8.5) emission scenarios, areas of high species richness are projected to decline by 22% and 45%, respectively, by the 2070s, with distribution centroids shifting northeastward and pronounced habitat loss in western lowland plains. Priority conservation targets include S. chinensis, D. suweonensis, and H. yangi, which combine narrow niches, restricted ranges, and high climate vulnerability. These findings provide a quantitative basis for climate-adaptive conservation planning for threatened herpetofauna in South Korea. Full article

Candida albicans, a commensal and opportunistic fungal pathogen, is a major clinical concern due to its ability to cause infections ranging from mild mucosal conditions to life-threatening systemic diseases, particularly in immunocompromised patients. Its capacity to form biofilms on medical devices further complicates treatment by enhancing antifungal resistance and immune evasion. In the search for novel therapeutic strategies, the lysine-enriched amphibian-derived temporin B analog, TB_KKG6K, has emerged as a promising antifungal agent. This study demonstrates that TB_KKG6K exhibits potent fungicidal activity against planktonic C. albicans cells, with a low potential to induce adaptation or resistance. TB_KKG6K has no adverse impact on the anti-Candida efficacy of standard antifungal drugs when applied in combination, interacting additively with amphotericin B and caspofungin in a fungicidal mode of action. Additionally, TB_KKG6K effectively reduces biofilm maturation on silicone elastomers, a material commonly used in medical devices, further highlighting its therapeutic potential. These data together with our previous documentation of minimal cytotoxicity and irritation potential in human cells makes TB_KKG6K a strong candidate for combating both planktonic and biofilm-associated C. albicans infections. These findings underscore the dual efficacy of TB_KKG6K and its potential to address the challenges posed by C. albicans in clinical settings. Full article

The Xenopus oocyte has long served as a versatile and powerful model for dissecting the molecular underpinnings of reproductive and developmental processes. Its large size, manipulability, and well-characterized cell cycle states have enabled generations of researchers to illuminate key aspects of oocyte maturation, fertilization, and early embryogenesis. This review provides an integrated overview of the cellular and molecular events that define the Xenopus oocyte’s transition from meiotic arrest to embryonic activation—or alternatively, to programmed demise if fertilization fails. We begin by exploring the architectural and biochemical landscape of the oocyte, including polarity, cytoskeletal organization, and nuclear dynamics. The regulatory networks governing meiotic resumption are then examined, with a focus on MPF (Cdk1/Cyclin B), MAPK cascades, and translational control via CPEB-mediated cytoplasmic polyadenylation. Fertilization is highlighted as a calcium-dependent trigger for oocyte activation. During fertilization in vertebrates, sperm-delivered phospholipase C zeta (PLCζ) is a key activator of Ca²⁺ signaling in mammals. In contrast, amphibian species such as Xenopus lack a PLCZ1 ortholog and instead appear to rely on alternative protease-mediated signaling mechanisms, including the uroplakin III–Src tyrosine kinase pathway and matrix metalloproteinase (MMP)-2 activity, to achieve egg activation. The review also addresses the molecular fate of unfertilized eggs, comparing apoptotic and necrotic mechanisms and their relevance to reproductive health. Finally, we discuss recent innovations in Xenopus-based technologies such as mRNA microinjection, genome editing, and in vitro ovulation systems, which are opening new avenues in developmental biology and translational medicine. By integrating classic findings with emerging frontiers, this review underscores the continued value of the Xenopus model in elucidating the fundamental processes of life’s origin. We conclude with perspectives on unresolved questions and future directions in oocyte and early embryonic research. Full article

Background/Objectives: Leishmaniasis is a neglected parasitic disease with significant global impact and limited therapeutic options due to the toxicity and cost of current treatments. Antimicrobial peptides (AMPs) derived from amphibians, such as Ocellatin-PT4 and Ocellatin-PT6, have emerged as promising bioactive molecules due to their antimicrobial properties and low toxicity to mammalian cells. This study evaluated the leishmanicidal and immunomodulatory effects of Ocellatin-PT4 and Ocellatin-PT6 against Leishmania amazonensis amastigotes. Methods: Peptides were tested on axenic amastigotes and macrophages infected with amastigotes. Cytotoxicity was assessed using MTT (0.4–197 µM for Ocellatin-PT4 and 0.3–152.1 µM for Ocellatin-PT6) and vital dye exclusion assays. Reactive oxygen species (ROS), nitric oxide (NO), and lipid droplet (LD) production were quantified to assess immunomodulatory responses. Results: Ocellatin-PT4 and Ocellatin-PT6 significantly reduced the viability of free and intracellular amastigotes at concentrations ≥ 24.7 µM and ≥19 µM, respectively, without affecting J774 macrophage viability. Infected macrophages treated with the peptides showed reduced parasite load and decreased infection index (≥12.3 µM for Ocellatin-PT4 and ≥2.4 µM for Ocellatin-PT6). Both peptides modulated the oxidative stress response: they reduced ROS levels in infected macrophages while only slightly increasing NO production at higher concentrations. Additionally, lipid droplet accumulation, which was increased during infection, was downregulated by both peptides—particularly by Ocellatin-PT6. Conclusions: Ocellatin-PT4 and Ocellatin-PT6 exert leishmanicidal effects and modulate key macrophage functions without cytotoxicity. These peptides represent promising candidates for the development of novel therapies against cutaneous leishmaniasis. Full article

The Gold-spotted pond frog (Pelophylax chosenicus (Okada, 1931)), classified as an endangered species in South Korea, has experienced significant population declines due to habitat loss, primarily driven by agricultural expansion and urbanization. This study aimed to assess the hibernation ecology of P. chosenicus using PIT tagging technology, focusing on its hibernation behavior, environmental conditions, and implications for conservation and restoration. Over a three-year period (2021–2024), PIT tags were implanted in 408 frogs, enabling continuous monitoring of hibernation sites and individual characteristics. The results revealed that hibernation depths ranged from 1 to 23 cm, with deeper burrowing observed during colder months, indicating a temperature-dependent survival strategy. The soil temperature at hibernation sites remained consistently higher than ambient air temperature, suggesting an adaptive mechanism to avoid freezing conditions. Additionally, frogs exhibited a strong preference for hibernation sites near water bodies, where soil moisture levels were high, highlighting the importance of preserving suitable microhabitats for successful overwintering. These findings provide valuable insights into the hibernation ecology of P. chosenicus and are critical for guiding effective habitat restoration initiatives. Future research should investigate physiological adaptations to varying hibernation environments and the potential impacts of climate change may impact the survival of this endangered species. Full article

The fluctuating temperature poses challenges to the survival of amphibians. This study employed two cold-adapted brown frog species, Rana dybowskii and Rana amurensis, from high-latitude cold regions as research models. We explored the mechanism by which contrasting peak daily habitat temperatures affect their physiological function and symbiotic microbial community. The results indicate that these two cold-adapted brown frog species exhibit a common physiological response of enhanced immune capacity and suppressed antioxidant capacity when subjected to elevated temperatures. However, they demonstrate unique coping strategies and physiological regulatory effects on gut microbiota: R. dybowskii activates its immune system by reducing the abundance of Actinobacteria and inhibiting metabolic pathways, but the decrease in Bacteroidetes abundance impairs antioxidant efficacy. On the other hand, R. amurensis experiences impairment of antioxidant function due to the regulatory effects of a significant increase in Proteobacteria and Actinobacteria, a marked decrease in Bifidobacterium, and a decline in gut microbiota α-diversity. For the first time, this study reveals the adaptive mechanisms by which two cold-adapted amphibian species respond to the contrasting peak daily habitat temperatures, providing a scientific basis for understanding how ectotherms react to climate change and for predicting their population dynamics. Full article

Phthalic acid esters (PAEs) are ubiquitous pollutants with reported endocrine-disruption and multiplex toxic activities in a wide range of invertebrate and vertebrate animals. In the present review, the molecular and physiological effects of phthalate exposure on invertebrates, as well as less characterized vertebrates such as amphibians, reptiles, and mammals, are thoroughly examined. PAEs induce a series of adverse effects, such as reproductive toxicity, oxidative stress, immune system impairment, and neuroendocrine disruption. The effects can extensively vary depending on the species, developmental stage, and environmental conditions, ranging from impaired hormone signaling, developmental malformations, and thyroid impairment in amphibians and reptiles to lipid metabolism disturbances and epigenetic changes in mammals. This review will place particular emphasis on transgenerational effects, mixture toxicity, and chronic low-level exposure. By integrating evidence from in vivo, in vitro, and omics studies, this review defines areas of knowledge gaps and the necessity to integrate these taxa in integrated ecological risk assessments, as well as regulatory policy. Full article

Madagascar is one of the world’s most prominent biodiversity hotspots and is characterized by exceptionally high amphibian diversity, with 429 currently described, mostly endemic species. However, cytogenetic research on Malagasy amphibians has been conducted only intermittently over the years. Previous studies, mostly using conventional staining and banding methods and often confined to single taxa or isolated families, have provided only partial insights into the karyotype evolution and genome organization of the major Malagasy clades. In this contribution, we present the first comprehensive synthesis of all available cytogenetic data on Malagasy anurans, including chromosome number and morphology, heterochromatin distribution, and chromosomal markers across the major endemic Malagasy families. By integrating and comparing results from decades of scattered studies, this review reveals consistent patterns of chromosomal diversification and identifies evolutionary trends associated with speciation and adaptive radiation in Malagasy amphibians. Overall, native Malagasy amphibian species can be subdivided into two main karyotype groups: the first includes karyotypes with only biarmed chromosomes (Heterixalus, Ptychadena, Boophis, Mantella, and Guibemantis), while the second comprises karyotypes with one or more uniarmed elements (Gephyromantis, Mantidactylus, and Microhylidae). The localization of NORs follows a diverse pattern, often varying even among closely related species. Heterochromatin distribution and composition also appear to be species-specific and thus taxonomically informative. Beyond summarizing existing knowledge, this work establishes a unified framework for interpreting chromosome evolution within the unique biogeography and evolutionary history of Madagascar. Our synthesis provides essential baseline data for future molecular, genomic, and conservation studies, thereby enhancing our understanding of the mechanisms that have generated and maintained the island’s extraordinary amphibian diversity. Full article

Background/Objectives: Hepcidin is a cysteine-rich antimicrobial peptide that links iron homeostasis and innate immunity in vertebrates, but its functions in amphibians remain poorly understood. The Chinese spiny frog (Quasipaa spinosa) is an economically important species that suffers serious losses from bacterial diseases. This study aimed to identify and functionally characterize a hepcidin homolog (QsHep) from Q. spinosa, focusing on its antibacterial activity, immunomodulatory effects on primary macrophages, and protective efficacy against Elizabethkingia miricola infection. Methods: The QsHep gene was cloned and analyzed, its tissue distribution and inducible expression were examined by qRT-PCR, and the synthetic peptide was tested for antimicrobial, membrane-disruptive, and immunomodulatory activities in vitro, as well as for in vivo protection in an E. miricola infection model. Results: QsHep encodes a typical preprohepcidin with a signal peptide, prodomain, and a conserved mature peptide containing eight cysteine residues. QsHep was widely expressed, with the highest levels in liver, and was significantly upregulated in liver and spleen following bacterial challenge. Synthetic QsHep displayed broad-spectrum antibacterial activity, including strong inhibition of E. miricola, and induced dose-dependent membrane damage in E. miricola. QsHep showed no obvious cytotoxicity but significantly enhanced chemotaxis, phagocytic activity, and respiratory burst in primary macrophages. In vivo, QsHep treatment markedly improved the survival of E. miricola-infected frogs in a dose-dependent manner. Conclusions: QsHep is an amphibian hepcidin that combines membrane-disruptive antibacterial activity with the activation of macrophage effector functions and confers significant protection against bacterial infection in vivo. These findings expand our understanding of hepcidin-mediated innate immunity in amphibians and highlight QsHep as a promising peptide candidate for controlling bacterial diseases in frog aquaculture. Full article

Facultative paedomorphosis, the retention of larval traits in sexually mature individuals, plays a crucial role in species ecology and evolution and is influenced by complex interactions between environmental factors. Here, we compile all known cases of paedomorphosis in all newt species in Greece and report 20 new localities, mainly in Northern Pindos National Park. Our results indicate that paedomorphosis tends to occur more frequently in stable aquatic environments in combination with unfavourable external conditions (lack of precipitation and higher temperatures). Furthermore, species-specific patterns related to the occurrence of paedomorphosis were also unveiled: Mesotriton alpestris prefers high-elevation and permanent ponds; Lissotriton graecus occurs predominantly in artificial, lowland ponds; and Triturus macedonicus is associated with a stable hydroperiod and fish absence. Overall, conservation strategies should explicitly account for paedomorphic populations, emphasizing the value of artificial ponds, which are able to support this life-history strategy. Lastly, the Northern Pindos Mountain Range emerges as a major European intra-specific diversity hotspot. Full article