Degenerative Osteoarthropathy in Laboratory Housed Xenopus (Silurana) tropicalis

In this case study, 15 adult laboratory Xenopus (Silurana) tropicalis (7 adult males and 8 adult females) were examinedfor nodular enlargements of the clawed digits (digits 0, I, II, and III) on the hind feet. Radiographs showed smoothly margined,rounded, peripherally mineralized lesions arising from the distal phalanges of digits 0-III with osteoproductive and osteolytic components in all frogs. Micro computed tomography (microCT) scans further revealed interphalangeal (IP),metacarpophalangeal (MCP), and metatarsophalangeal (MTP) joint osteoarthritis characterized by periarticular new bone formation, rounded mineral foci both peripherally and centrally within the joints, and more rarely, linear mineralizationpalmar/plantar to the joints in the flexor tendons. In the nonclawed digits, the shape of the distal phalanx was variablydistorted and both subluxation and malangulation of IP joints were identified. Histologically, nodules corresponded to aperipheral rim of mature cortical bone surrounding central adipose tissue, scattered hematopoietic elements, and residualbone of the distal phalanx. Occasionally, the peripheral rim of cortical bone extended proximally to encompass the distalaspect of adjacent phalanx. MCP, MTP and IP joint spaces of most digits exhibited widespread osteoarthritis characterizedby periarticular cartilaginous or osseous metaplasia, bony remodeling, and less frequently, granulomatous osteomyelitis.Nutritional analyses of the feed did not indicate imbalances nor were the lesions consistent with metabolic bone disease.The exact etiopathogenesis of these lesions is unknown; however, we hypothesize that the osteoarthritic changes are due toa combination of the frogs’ mature age, the unique structure of the Xenopus spp. claw, genetics and biomechanical forces onthe digits and distal phalanges of the hind feet.

Parasitic helminth infection in anurans from Ozomo Wetland, Edo State, Nigeria

Anurans from Ozomo Wetland were examined for parasitic helminth infection. Among these anurans were Arthroleptis poecilonotus, Arthroleptis sp., Leptopelis occidentalis, L. spiritusnoctus, Sclerophrys maculata, Hoplobatrachus occipitalis, Hyperolius concolor, H. fusciventris burtoni Phase B, Hyperolius sp., Afrixalus dorsalis, Ptychadena bibroni, P. longirostris, P. mascareniensis, P. oxyrhynchus, P. pumilio, Hemisus marmoratus and Silurana tropicalis. The prevalence and intensity of infection recorded in the anurans were 58.2% and 9.5 parasites/infected host, respectively. Eighteen parasite species were recovered and these include the monogeneans (Polystoma aeschilimanni, P. prudhoei and P. prucei); digeneans (Diplodiscus fischthalicus, Metahaematoloechus micrurus and Mesocoelium monodi) and nematodes (Amplicaecum sp., Aplectana sp., Batrachocamallanus siluranae, Camallanus dimitrovi, Chabaudus leberrei, Cosmocerca commutata, C. ornata, Physaloptera sp., Rhabdias africanus, Rhabdias sp., an unidentified nematode and an unidentified oxyurid nematode). These parasites were recovered from different microhabitats (oesophagus/stomach, small intestine, large intestine/rectum lungs and urinary bladder) in the anuran hosts. Nematode was the dominant parasite with 66.7% infection while the monogeneans and digeneans had 16.7% infection each. Metahaematoloechus micrurus recorded in this study had unusually large testes which have not been observed in other specimens recorded elsewhere and there is need for further investigation. Keywords: anurans, species, farming, logging, deforestation, digeneans, nematodes, prevalence, intensity, Nigeria

Polybrominated Diphenylether (DE-71) Exposure Skews Phenotypic Sex Ratio, and Alters Steroid Hormone Levels and Steroidogenic Enzyme Activities in Juvenile Silurana tropicalis

The impact of the brominated flame-retardant mixture, DE-71, on gonadal steroidogenesis during sexual differentiation in Silurana tropicalis was examined. A partial lifecycle study exposing S. tropicalis to varying concentrations of DE-71 (0.0, 0.65, 1.3, 2.5, and 5.0 μg/l [nominal]) was conducted from early gastrula-stage embryo to 150 days postmetamorphosis (dpm). Exposure of S. tropicalis to DE-71 induced liver necrosis and induced abnormal ovary development characterized by previtellogenic oocyte necrosis and arrested development of vitellogenic oocytes in females in a concentration-dependent manner. Decreased mean plasma dihydrotestosterone (DHT) and T, gonad T, and increased mean plasma E2 levels were found in 150 dpm DE-71-treated male S. tropicalis compared to controls. Plasma E2 levels in females were not significantly altered compared to control S. tropicalis, although lower plasma and gonad T were detected. Mean gonadal CYP 19 aromatase activity in both male and female S. tropicalis exposed to DE-71 was not appreciably affected. Decreased mean male 5α-reductase and CYP17 activities in both male and females were observed compared to control frogs. Overall, these studies suggested that PBDE exposure induced liver necrosis and abnormal ovary development; and reduced circulating and gonadal androgens resulting in a phenotypic skew in sex ratio toward the female sex in S. tropicalis.