Characterising the Effect of Wnt/ß-Catenin Signalling on Melanocyte Development and Patterning: Insights from Zebrafish (Danio rerio).

Zebrafish (Danio rerio) is a well-established model organism for studying melanocyte biology due to its remarkable similarity to humans. The Wnt signalling pathway is a conserved signal transduction pathway that plays a crucial role in embryonic development and regulates many aspects of the melanocyte lineage. Our study was designed to investigate the effect of Wnt signalling activity on zebrafish melanocyte development and patterning. Stereo-microscopic examinations were used to screen for changes in melanocyte count, specific phenotypic differences, and distribution in zebrafish, while microscopic software tools were used to analyse the differences in pigment dispersion of melanocytes exposed to LiCl (Wnt enhancer) and W-C59 (Wnt inhibitor). Samples exposed to W-C59 showed low melanocyte densities and defects in melanocyte phenotype and patterning, whereas LiCl exposure demonstrated a stimulatory effect on most aspects of melanocyte development. Our study demonstrates the crucial role of Wnt signalling in melanocyte lineage and emphasises the importance of a balanced Wnt signalling level for proper melanocyte development and patterning.

First Record of Spirometra erinaceieuropaei spargana Infection in Amphibians of South Asia: A Causative Agent of Surficial Abnormalities.

Background: Sparganosis is a zoonotic disease caused by Plerocercoid larvae (spargana) of the genus Spirometra. We aimed to provide molecular evidence for the infection of amphibians with Spirometra sp. in the inside and outside of Horton Plains National Park (HPNP), Sri Lanka. Methods: The prevalence of sparganum infection in wild frogs (Truga eques and Minverya agricola) was investigated in the inside and outside of HPNP from June 2019 to April 2021.A total of 1,434 Amphibians samples were surveyed to examine the spargana infection from the study site. To identify the species identity of the collected spargana, a portion of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene and nuclear 18S rRNA gene were amplified, sequenced, and analyzed. Results: A total of 539 infected amphibians (T. eques and M. agricola) samples were examined to survey from the study area. Spargana were detected in all dissected specimens belonging to the species Spirometra erinaceieuropaei that were genetically confirmed using the evolutionary conserved nuclear 18S rRNA gene and then compared to the GenBank deposit, indicating that S. erinaceieuropaei is the primary causal agent of sparganosis both inside and outside the HPNP. Conclusion: Our finding is the first genetically confirmed record of S. erinaceieuropaei in amphibians in South Asia. However, further studies are needed to investigate the prevalence of sparagna infection in amphibians all over the island.

Effect of Embryonic Alcohol Exposure on Craniofacial and Skin Melanocyte Development: Insights from Zebrafish (Danio rerio).

Alcohol is a common addictive substance and prenatal alcohol exposure could cause fetal alcohol spectrum disorder (FASD) and can lead to various birth defects. The small teleost zebrafish (Danio rerio) has been identified as a fine animal model in developmental biology and toxicological research. Zebrafish models are widely used to study the harmful effects of alcohol and limited studies are available on the craniofacial and skin malformations associated with FASD. The present study attempts to investigate the effect of alcohol on early zebrafish embryonic development. The effects of prenatal alcohol exposure on neural crest cell-derived organ formation, including pharyngeal dentition, palatal bones and skin melanocytes were analysed. Whole-mount cartilage and bone staining and imaging techniques were applied to determine the effects of alcohol on the above-mentioned structures. The tooth size and shape were affected by alcohol exposure, but the number of teeth in the pharyngeal dentition was not affected. Only first-generation teeth showed size differences. The alcohol-exposed ethmoid bone, which is homologous to the human hard palate, was smaller and less dense in cell arrangement compared with the control medial ethmoid bone. The skin pigmentation defects included reduced melanocyte density, melanin contraction, smaller melanocyte surface area and aberrations in melanosome dispersion, revealing that alcohol significantly influenced and downregulated each and every step of the melanocyte developmental process. This descriptive study summarises the effects of alcohol on the development of neural crest cell-derived structures and highlights the importance of zebrafish in studying the phenotypic characteristics of fetal alcohol spectrum disorder.