Background Regeneration studies help to understand the strategies that replace a lost or damaged organ and provide insights into approaches followed in regenerative medicine and engineering. Amphibians regenerate their limbs effortlessly and are indispensable models to study limb regeneration. Xenopus and axolotl are the key models for studying limb regeneration but recent studies on non-model amphibians have revealed species specific differences in regeneration mechanisms. Results The present study describes the de novo transcriptome of intact limbs and three-day post-amputation blastemas of tadpoles and froglets of the Asian tree frog Polypedates maculatus, a non-model amphibian species commonly found in India. Differential gene expression analysis between early tadpole and froglet limb blastemas discovered species-specific novel regulators of limb regeneration. The present study reports upregulation of proteoglycans, such as epiphycan, chondroadherin, hyaluronan and proteoglycan link protein 1, collagens 2,5,6, 9 and 11, several tumour suppressors and methyltransferases in the P. maculatus tadpole blastemas. Differential gene expression analysis between tadpole and froglet limbs revealed that in addition to the expression of larval-specific haemoglobin and glycoproteins, an upregulation of cysteine and serine protease inhibitors and downregulation of serine proteases, antioxidants, collagenases and inflammatory genes in the tadpole limbs were essential for creating an environment that would support regeneration. Dermal myeloid cells were GAG+, EPYC+, INMT+, LEF1+ and SALL4+ and seemed to migrate from the unamputated regions of the tadpole limb to the blastema. On the other hand, the myeloid cells of the froglet limb blastemas were few and probably contributed to sustained inflammation resulting in healing. Conclusions Studies on non-model amphibians give insights into alternate tactics for limb regeneration which can help devise a plethora of methods in regenerative medicine and engineering.

Aim/Background: The present study, examined the impact of excess Vitamin A on feeding and pre-metamorphic tadpoles of Microhyla nilphamariensis to analyse its dose-dependent and stage-specific lethal and teratogenic effects. Materials and Methods: Feeding and pre-metamorphic stage tadpoles were subjected to varying concentrations of commercially available Vitamin A palmitate for different time intervals. The control and treated tadpoles were fixed 5, 10-and 15-Days Post Treatment (dpt) in neutral buffered formalin for morphological analyses, morphometry and histology. Results: In both feeding and pre-metamorphic stages, mortality was high when exposed to higher concentrations and longer duration (48-96 hr). When exposed for 24 hr, the treated tadpoles showed significant differences in morphometry, and abnormalities in the eye and intestine of the feeding stages and eye and kidneys of pre-metamorphic stages. Significantly, most of the treated tadpoles died before attaining metamorphosis and those that survived had a delayed metamorphosis with abnormalities. Conclusion: Vitamin A is lethal to the tadpoles of Microhyla nilphamariensis at high concentrations and at lower concentrations it affects the thyroid hormone function and causes abnormalities of various kinds.