HELICOBACTER SCREENING OF GRAND CAYMAN BLUE IGUANA (CYCLURA LEWISI) AND NORTH ANTILLEAN SLIDER (TRACHEMYS DECUSSATA ANGUSTA) ON GRAND CAYMAN, CAYMAN ISLANDS.

The endemic Grand Cayman or blue iguana (Cyclura lewisi) is endangered. Beginning in 2015 significant morbidity and mortality occurred in captive and wild blue iguanas within Grand Cayman's Queen Elizabeth II Botanic Park (QEIIBP). Investigation identified a novel Helicobacter sp., provisionally named Helicobacter sp. Grand Cayman Blue Iguana 1 (GCBI1), as the cause. Invasive green iguanas (Iguana iguana) are believed to play a role in GCBI1 transmission to the blue iguana; however, the origin and transmission pathways have not been determined. To assess the likelihood of blue iguanas asymptomatically harboring GCBI1, in May 2022 population-level screening of captive blue iguanas at QEIIBP was conducted on half (n = 102) of the captive blue iguana population (n = 201) including half of each age class. Helicobacter sp. GCBI1 is closely related to a chelonian Helicobacter sp. and 10 sympatric wild north Antillean sliders (Trachemys decussata angusta) were sampled in October 2019. Combined choana/cloacal swabs were screened by a GCBI1-specific quantitative polymerase chain reaction (qPCR) assay. All samples were negative, suggesting that GCBI1 is not present asymptomatically in the captive blue iguana population or in north Antillean sliders. These results provide support for the hypothesis that GCBI1 is periodically introduced to captive and wild blue iguanas from another species or source.

Non-covalent inhibitors of thioredoxin glutathione reductase with schistosomicidal activity in vivo.

Only praziquantel is available for treating schistosomiasis, a disease affecting more than 200 million people. Praziquantel-resistant worms have been selected for in the lab and low cure rates from mass drug administration programs suggest that resistance is evolving in the field. Thioredoxin glutathione reductase (TGR) is essential for schistosome survival and a validated drug target. TGR inhibitors identified to date are irreversible and/or covalent inhibitors with unacceptable off-target effects. In this work, we identify noncovalent TGR inhibitors with efficacy against schistosome infections in mice, meeting the criteria for lead progression indicated by WHO. Comparisons with previous in vivo studies with praziquantel suggests that these inhibitors outperform the drug of choice for schistosomiasis against juvenile worms.

New structures of Class II Fructose-1,6-Bisphosphatase from Francisella tularensis provide a framework for a novel catalytic mechanism for the entire class.

Class II Fructose-1,6-bisphosphatases (FBPaseII) (EC: 3.1.3.11) are highly conserved essential enzymes in the gluconeogenic pathway of microorganisms. Previous crystallographic studies of FBPasesII provided insights into various inactivated states of the enzyme in different species. Presented here is the first crystal structure of FBPaseII in an active state, solved for the enzyme from Francisella tularensis (FtFBPaseII), containing native metal cofactor Mn2+ and complexed with catalytic product fructose-6-phosphate (F6P). Another crystal structure of the same enzyme complex is presented in the inactivated state due to the structural changes introduced by crystal packing. Analysis of the interatomic distances among the substrate, product, and divalent metal cations in the catalytic centers of the enzyme led to a revision of the catalytic mechanism suggested previously for class II FBPases. We propose that phosphate-1 is cleaved from the substrate fructose-1,6-bisphosphate (F1,6BP) by T89 in a proximal α-helix backbone (G88-T89-T90-I91-T92-S93-K94) in which the substrate transition state is stabilized by the positive dipole of the 〈-helix backbone. Once cleaved a water molecule found in the active site liberates the inorganic phosphate from T89 completing the catalytic mechanism. Additionally, a crystal structure of Mycobacterium tuberculosis FBPaseII (MtFBPaseII) containing a bound F1,6BP is presented to further support the substrate binding and novel catalytic mechanism suggested for this class of enzymes.

A description of the tadpole of the Critically Endangered Botsford's leaf-litter frog (Leptobrachella botsfordi) with comments on the distribution and conservation status of the species.

We describe the tadpole of the Botsford's leaf-litter frog Leptobrachella botsfordi, a species endemic to Mount Fansipan in northwest Vietnam, for the first time. Tadpoles of this species were found in steep, fast-flowing streams at elevations between 2500-2600 m asl. We also report a previously unknown locality for this species on Mount Fansipan, which increases the species' known Extent of Occurrence from 8 km2 to 36 km2. Our findings will inform subsequent conservation initiatives for this poorly known and highly threatened species.

Comparison of the nutritional content of the captive and wild diets of the critically endangered mountain chicken frog (Leptodactylus fallax) to improve its captive husbandry.

It is vital to provide appropriate nutrition to maintain healthy populations in conservation breeding programs. Knowledge of the wild diet of a species can be used to inform captive diet formulation. The nutritional content of the wild diet of the critically endangered mountain chicken frog (Leptodactylus fallax) is unknown, like that of most amphibians. In this study, we analyzed the nutritional content of food items that comprise 91% of the wild diet of L. fallax, by dry weight of food items, and all food items offered to captive L. fallax at ZSL London Zoo and Jersey Zoo. We subsequently compared the nutritional content of the wild diet and captive diet at ZSL London Zoo consumed by L. fallax. To the authors' knowledge, this is the first study to directly compare the nutritional content of the wild and captive diets of an anuran amphibian. The captive diet at ZSL London Zoo, without dusting of nutritional supplements, was higher in gross energy and crude fat and lower in ash, calcium and calcium:phosphorus ratio than the wild diet. Most of the food items in the captive diets had a high omega-6:omega-3 fatty acid ratio and in the wild diet had a low omega-6:omega-3 fatty acid ratio. We recommend a combination of modifications to the captive diets to better reflect the nutritional content of the wild diet. Nutritional analysis of captive and wild diets is recommended for other species in conservation breeding programs to improve captive husbandry and ultimately fitness.

Development of a body condition score for the mountain chicken frog (Leptodactylus fallax).

The Critically Endangered mountain chicken frog (Leptodactylus fallax) has undergone drastic population decline due to habitat loss, hunting, invasive species, and chytridiomycosis. In response, several partner institutions initiated a conservation breeding program. It is important to maintain the captive population in good health. Therefore the program partners have recommended establishment of protocols for health examination of the species, including body condition assessment. Visual body condition scoring is a useful means to assess body condition in zoo animals for which regular bodyweight measurements are impractical or associated with capture-related stress. In this study, the authors developed a visual body condition score for the mountain chicken frog based on an ordinal categorical scale from 1 to 5 (1 = lowest body condition, 5 = highest body condition) using anatomical features that vary with total body energy reserves. Veterinary staff, animal managers, keepers, researchers, and students subsequently used the body condition score to assign scores to 98 mountain chicken frogs (41 male, 57 female) aged between 8 months and 12 years housed in five zoos in the UK and Jersey between February and March 2016. Body condition scores showed moderate (rho = 0.54; males) to strong (rho = 0.6; females) correlation with the scaled mass index, an objective measure of total energy reserves. The majority of pairwise comparisons between scores showed slight to substantial intra-observer agreement (93.8%) and slight to almost perfect inter-observer agreement (97.2%). Cases of poor agreement were likely due to limited observer experience working with the species.