M. Lagzian - Department of Biology, Faculty of sciences, University of Sistan and Baluchestan, Zahedan, Iran
M. Ghanbarifardi - Department of Biology, Faculty of sciences, University of Sistan and Baluchestan, Zahedan, Iran

Molecular adaptation of mudskippers to land living is undoubtedly a complex multifactorial phenomenon, and the skin is one of the most influential factors. This study explores the behavior of collagen type-I (CT۱) from the structural and functional point of view using an in-silico approach and discusses its possible role in the adaptation to aerial respiration. The approach was started by finding the CT۱ triple helix gene and protein of Boleophthalmus pectinirostris, Periophthalmus magnuspinnatus, and Danio rerio (as the reference sample), followed by homology modeling and ۱۰۰ ns molecular dynamics simulation. Subsequently, the trajectories were analyzed for RMSD, RMSF, Rg, H-bond, and SASA. The results all together showed that the flexibility of the CT۱ of Danio rerio is considerably greater than Boleophthalmus, and the latter is more flexible than Periophthalmus. This difference in flexibility is also evident in the morphology of their skin since Zebrafish's skin is more elastic than the two mudskippers. The skin of Boleophthalmus is as well slightly softer than Periophthalmus. Our findings demonstrate that the more terrestrial species have the less flexible CT۱ in the skin that saves them from desiccation. However, the skin structure of mudskippers makes a balance between the capability of respiration and saving them from desiccation. The results reveal one of the phenotypic adaptations of mudskippers for living on land, which is congruent with the morphological and physiological distinctive features.

Mudskipper, Collagen, Molecular Dynamics, Water to Land Transition