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Journal of Zoo and Wildlife Medicine :... Jun 2024Chytridiomycosis caused by () has been documented in greater sirens () in the wild and in the pet trade. This study evaluated the use of terbinafine-impregnated...
Chytridiomycosis caused by () has been documented in greater sirens () in the wild and in the pet trade. This study evaluated the use of terbinafine-impregnated implants for chytridiomycosis prophylaxis in greater sirens exposed to . Implants were placed intracoelomically in both control (blank implant, n = 4) and treatment (24.5 mg of terbinafine implant, n = 4) groups. Sirens were exposed to zoospores via 24-h immersion bath at 1 and 2 mon postimplant placement. Blood was collected monthly for plasma terbinafine levels, and skin swabs were collected weekly for quantitative PCR. Animals with terbinafine implants had detectable concentrations of plasma terbinafine ranging from 17 to 102 ng/ml. Only one terbinafine-implanted animal had a peak concentration above the published minimum inhibitory concentration for terbinafine against zoospores (63 ng/ml); however, it is unknown how plasma terbinafine concentrations relate to concentrations in the skin. There was no difference between the two treatment groups in clinical signs or clearance rate, and no adverse effects from implants were observed. These findings indicate using intracoelomic drug implants for drug delivery in amphibians is safe; however, terbinafine efficacy in preventing chytridiomycosis in sirens remains unclear. Further investigation of the use of intracoelomic implants and identification of effective drugs and doses in other amphibian species against and other infectious diseases is warranted, as this may provide a practical method for long-term drug delivery in wildlife.
Topics: Terbinafine; Animals; Pilot Projects; Antifungal Agents; Drug Implants; Batrachochytrium; Male; Mycoses; Amphibians
PubMed: 38875202
DOI: 10.1638/2023-0010 -
Journal of Zoo and Wildlife Medicine :... Jun 2024The mass extinction of amphibians necessitates specialized programs to ensure species' survival. Maryland Zoo in Baltimore houses the largest assurance population of the...
The mass extinction of amphibians necessitates specialized programs to ensure species' survival. Maryland Zoo in Baltimore houses the largest assurance population of the critically endangered Panamanian golden frog (). However, individuals in this population experience a tetany-like syndrome, characterized by rigid/inappropriately positioned limbs and difficulty hopping, swimming, and righting. In this study, a syndrome case definition was assigned and the associated clinical signs were described. Then, four different treatments were systematically assessed in order to find the most effective protocol for treatment and begin to elucidate its underlying causes. Eighty-three frogs fulfilled the case definition and were treated orally for 14 d with either calcium gluconate, magnesium chloride, supplemental gavage feeding, or combination of calcium, magnesium, and vitamin B complex. Frogs were tested with a defined protocol assessing hopping, righting, and swimming abilities. Testing was performed at symptom onset and repeated weekly until resolution occurred. Analyses revealed that combination treatment was significantly more effective in eliminating clinical signs of tetany syndrome. Results show the most effective way to treat this syndrome, but do not help elucidate the underlying cause. Future work will focus on examining factors (e.g., diet, husbandry) that may elicit the syndrome for a more complete understanding of its etiology.
Topics: Animals; Tetany; Anura; Animals, Zoo; Male; Female; Vitamin B Complex
PubMed: 38875201
DOI: 10.1638/2023-0075 -
Journal of Zoo and Wildlife Medicine :... Jun 2024Panamanian golden frog (PGF) () is a critically endangered species. The Maryland Zoo in Baltimore houses two groups of PGF originating from distinct geographic locations...
Panamanian golden frog (PGF) () is a critically endangered species. The Maryland Zoo in Baltimore houses two groups of PGF originating from distinct geographic locations as an assurance colony, with the goal of upholding genetics for future release of individuals back to their native environment. The purpose of this cross-sectional study was to characterize the prevalence of ocular abnormalities in these two zoo-housed populations of PGF as well as to establish normal parameters for selected diagnostic tests in these groups. Twenty-five females and 25 males were randomly selected from each group (100 PGF; 200 eyes in total) to undergo ocular examination using slit lamp biomicroscopy and direct ophthalmoscopy. Endodontic absorbent paper point test (EAPPT) and intraocular pressure (IOP) and Rose Bengal stain diagnostic tests were also performed. Reference ranges for tear production (EAPPT, 0.5-3 mm/min) and IOP (14-26 mmHg) were calculated in the nondiseased PGF eyes ( = 160 eyes). Rose Bengal stain uptake was negative on all eyes. In total, 40 eyes of 30 PGF were found to have some form of ocular abnormality (28% of PGF, 20% of eyes). The most frequently observed ocular abnormalities were cataract (9% of PGF, 6% of eyes) and keratitis (nonlipid keratopathy; 10% of PGF, 5.5% of eyes). There was no significant difference in overall ocular abnormality prevalence between the two groups studied ( = 0.37) or between the sexes ( = 0.76). The median age of an eye with cataract and keratitis (nonlipid keratopathy) was 10.35 and 7.7 yr, respectively. Ocular abnormalities are common in these two populations of PGF. Documentation of these ocular abnormalities and establishment of diagnostic reference ranges have not previously been published and may be important for maintaining the health of this endangered species.
Topics: Animals; Female; Male; Prevalence; Cross-Sectional Studies; Anura; Animals, Zoo; Eye Abnormalities; Reference Values; Endangered Species; Eye Diseases; Baltimore
PubMed: 38875189
DOI: 10.1638/2023-0072 -
Genome Biology and Evolution Jun 2024Aposematic organisms rely on their conspicuous appearance to signal that they are defended and unpalatable. Such phenotypes are strongly tied to survival and...
Aposematic organisms rely on their conspicuous appearance to signal that they are defended and unpalatable. Such phenotypes are strongly tied to survival and reproduction. Aposematic colors and patterns are highly variable; however, the genetic, biochemical and physiological mechanisms producing this conspicuous coloration remain largely unidentified. Here, we identify genes potentially affecting color variation in two color morphs of Ranitomeya imitator: the orange-banded Sauce and the redheaded Varadero morphs. We examine gene expression in black and orange skin patches from the Sauce morph and black and red skin patches from the Varadero morph. We identified genes differentially expressed between skin color patches, including those that are involved in melanin synthesis (e.g., mlana, pmel, tyrp1), iridophore development (e.g., paics, ppat, ak1), pteridine synthesis (e.g., gch1, recql4, xdh), and carotenoid metabolism (e.g., dgat2, rbp1, scarb2). In addition, using weighted gene network analysis, we identified the top 50 genes with high connectivity from the most significant network associated with gene expression differences between color morphs. Of these 50 genes, 14 were known to be related to color production (gch1, gmps, gpr143, impdh1, mc1r, pax3-a, pax7, ppat, rab27a, rlbp1, tfec, trpm1, xdh).
PubMed: 38874406
DOI: 10.1093/gbe/evae123 -
Ecology and Evolution Jun 2024Active forms of cannibalism that involve predation of live conspecifics occur widely among amphibians, most notably by tadpoles that feed on each other and adults that...
Active forms of cannibalism that involve predation of live conspecifics occur widely among amphibians, most notably by tadpoles that feed on each other and adults that feed on juveniles. In contrast, cannibalism among amphibian adults (adult-adult cannibalism) is less often reported and there have been no investigations on the occurrence of sexual cannibalism in this group to date. In this study, we present an observation of potential sexual cannibalism involving an adult female green and golden bell frog, , preying on a conspecific adult male during the species' breeding season. By comparing our observation to the available literature, we show that adult-adult cannibalism among amphibians is rare but tends to be committed by females against their male counterparts. We thus suggest that the occurrence of sexual cannibalism should be extended to include this group, where sexual size dimorphism occurs widely among adults that congregate spatially during breeding periods, both predictors of intra-specific predation. We hypothesise that amphibian females may be able to exploit male advertisement calls to differentiate suitable partners from potential prey and that male individuals are vulnerable to sexual cannibalism as they must risk attracting and physically exposing themselves to females in order to reproduce. Our findings reveal the complex dynamics that exist within adult amphibian populations, suggesting that females may have a choice when deciding how to interact with and utilise their male counterparts. As our findings are preliminary, based on a small sample size of records, including several from captive individuals, we encourage authors to publish their observations of cannibalism in the field, including unsuccessful attempts, to confirm the presence of sexual cannibalism in this group.
PubMed: 38873021
DOI: 10.1002/ece3.11576 -
Bio-protocol Jun 2024Many studies on mosquito biology rely on laboratory-reared colonies, emphasizing the need for standardized protocols to investigate critical aspects such as disease...
Many studies on mosquito biology rely on laboratory-reared colonies, emphasizing the need for standardized protocols to investigate critical aspects such as disease biology, mosquito behavior, and vector control methods. While much knowledge is derived from anthropophilic species from genera like , and , there is a growing interest in studying mosquitoes that feed on non-human hosts. This interest stems from the desire to gain a deeper understanding of the evolution of diverse host range use and host specificity. However, there is currently a limited number of comprehensive protocols for studying such species. Considering this gap, we present a protocol for rearing , a mosquito species specialized in feeding on anuran amphibians by eavesdropping on host-emitted sound cues. Additionally, we provide instructions for successfully shipping live specimens to promote research on this species and similar ones. This protocol helps fill the current gap in comprehensive guidelines for rearing and maintaining colonies of anuran host-biting mosquitoes. It serves as a valuable resource for researchers seeking to establish colonies of mosquito species from the Uranotaeniini tribe. Ultimately, this protocol may facilitate research on the evolutionary ecology of Culicidae, as this family has recently been proposed to have originated from a frog-feeding ancestor. Key features • Rearing and maintenance of colonies of non-human host-biting mosquitoes that feed on frogs using host-emitted acoustic cues. • Provides shipping guidelines aimed to enhance the establishment of colonies by new research groups and specimen exchanges between labs.
PubMed: 38873019
DOI: 10.21769/BioProtoc.4996 -
Integrative Zoology Jun 2024Chytridiomycosis, an infectious skin disease caused by the chytrid fungi, Batrachochytrium dendrobatidis and B. salamandrivorans, poses a significant threat to amphibian...
Environmental factors and host sex influence the skin microbiota structure of Hong Kong newt (Paramesotriton hongkongensis) in a coldspot of chytridiomycosis in subtropical East Asia.
Chytridiomycosis, an infectious skin disease caused by the chytrid fungi, Batrachochytrium dendrobatidis and B. salamandrivorans, poses a significant threat to amphibian biodiversity worldwide. Antifungal bacteria found on the skin of chytrid-resistant amphibians could potentially provide defense against chytridiomycosis and lower mortality rates among resistant individuals. The Hong Kong newt (Paramesotriton hongkongensis) is native to East Asia, a region suspected to be the origin of chytrids, and has exhibited asymptomatic infection, suggesting a long-term coexistence with the chytrids. Therefore, the skin microbiota of this resistant species warrant investigation, along with other factors that can affect the microbiota. Among the 149 newts sampled in their natural habitats in Hong Kong, China, putative antifungal bacteria were found in all individuals. There were 314 amplicon sequence variants distributed over 25 genera of putative antifungal bacteria; abundant ones included Acinetobacter, Flavobacterium, and Novosphingobium spp. The skin microbiota compositions were strongly influenced by the inter-site geographical distances. Despite inter-site differences, we identified some core skin microbes across sites that could be vital to P. hongkongensis. The dominant cores included the family Comamonadaceae, family Chitinophagaceae, and class Betaproteobacteria. Moreover, habitat elevation and host sex also exhibited significant effects on skin microbiota compositions. The antifungal bacteria found on these newts offer an important resource for conservation against chytridiomycosis, such as developing probiotic treatments for susceptible species.
PubMed: 38872359
DOI: 10.1111/1749-4877.12855 -
Scientific Reports Jun 2024Decreases in body sizes of animals related to recent climate warming can affect population persistence and stability. However, direct observations of average sizes over...
Decreases in body sizes of animals related to recent climate warming can affect population persistence and stability. However, direct observations of average sizes over time and their interrelationships with underlying density-dependent and density-independent processes remain poorly understood owing to the lack of appropriate long-term datasets. We measured body size of two species common to headwater streams in coastal and Cascades ecoregions of the Pacific Northwest of North America over multiple decades, comparing old-growth and managed forests. We found consistent decreases in median length of Coastal Cutthroat Trout Oncorhynchus clarkii clarkii, but a coexisting species, the Coastal Giant Salamander Dicamptodon tenebrosus, appears to be more resilient to size changes over time. Based on observed trends, adult trout have decreased in length by 6-13% over the last 30 years. Length decreased more in larger compared to smaller animals, suggesting that these effects reflect changes in growth trajectories. Results from a model-selection approach that included hydroclimatic and biological information as covariates in one of our study ecoregions demonstrated that stream temperature alone did not explain observed length reductions. Rather, a combination of density-dependent (animal abundances) and local density-independent factors (temperature, habitat, and streamflow) explained observed patterns of size. Continued decreases in size could lead to trophic cascades, biodiversity loss, or in extreme cases, species extirpation. However, the intricate links between density-independent and density-dependent factors in controlling population-level processes in streams need further attention.
Topics: Animals; Urodela; Body Size; Trout; Ecosystem; Rivers; Climate Change; Temperature
PubMed: 38871823
DOI: 10.1038/s41598-024-64145-x -
Chemosphere Aug 2024Ciprofloxacin (CIP) and levofloxacin (LEV) are broad-spectrum antibiotics with potent antibacterial activity. Although many studies have shown that antibiotics can lead...
Ciprofloxacin (CIP) and levofloxacin (LEV) are broad-spectrum antibiotics with potent antibacterial activity. Although many studies have shown that antibiotics can lead to gut microbiota disruption, the effects of CIP and LEV on gut microbial colonization at the embryonic stage remain poorly characterized. Here, we evaluated the response of Bufo gargarizans embryos in terms of gut microbiota colonization, growth and developmental stages to CIP and LEV exposure. Embryos treated with 100 μg/L CIP and LEV exhibited significantly reduced diversity and richness of the gut microbiota, as well as altered community structure. Both CIP and LEV treatments resulted in an increase in the pathogenic bacteria Bosea and Aeromonas, and they appeared to be more resistant to CIP than LEV. Additionally, CIP exposure caused reduced total length and delayed the development in B. gargarizans embryos, while LEV increased the total length and promoted embryonic development. The present study revealed the adverse effects of CIP and LEV exposure on host gut microbiota, growth and development during the embryonic stage, and contributed new perspectives to the evaluation of early aquatic ecological risk under CIP and LEV exposure.
Topics: Ciprofloxacin; Gastrointestinal Microbiome; Animals; Levofloxacin; Anti-Bacterial Agents; Bufonidae; Water Pollutants, Chemical; Embryo, Nonmammalian; Bacteria
PubMed: 38871193
DOI: 10.1016/j.chemosphere.2024.142587 -
PloS One 2024The chytrid fungus Batrachochytrium salamandrivorans [Bsal] is causing declines in the amphibian populations. After a decade of mapping the pathogen in Europe, where it...
The chytrid fungus Batrachochytrium salamandrivorans [Bsal] is causing declines in the amphibian populations. After a decade of mapping the pathogen in Europe, where it is causing dramatic outbreaks, and North America, where its arrival would affect to the salamander's biodiversity hotspot, little is known about its current status in Asia, from presumably is native. Japan has several species considered as potential carriers, but no regulation is implemented against Bsal spreading. Previous Bsal known presence detected various cases on the Okinawa Island, southwestern Japan. Previous studies on its sister species, B. dendrobatidis presented a high genomic variation in this area and particularly on Cynops ensicauda. Here, we have done the largest monitoring to date in Japan on the Cynops genus, focusing on Okinawa Island and updating its distribution and providing more information to unravel the still unknown origin of Bsal. Interestingly, we have provided revealing facts about different detectability depending on the used molecular techniques and changes in its Japanese distribution. All in all, the Bsal presence in Japan, together with its low variability in the sequenced amplicons, and the lack of apparent mortalities, may indicate that this part of Asia has a high diversity of chytrids.
Topics: Animals; Japan; Urodela; Batrachochytrium; Phylogeny; Genetic Variation; Biodiversity; Chytridiomycota; Mycoses; East Asian People
PubMed: 38870137
DOI: 10.1371/journal.pone.0305228