Effects of elevated carbon dioxide on contraction force and proteome composition of sea urchin tube feet

This study examined how contraction force and protein profiles of the tube feet of the sea urchin (Pseudocentrotus depressus) were affected when acclimated to 400 (control), 2000 and 10,000μatm CO₂ for 48days. Acclimation to higher CO₂ conditions significantly reduced contraction force of the tube feet. Two-dimensional gel electrophoresis showed that eight spots changed in protein volume: six up-regulated and two down-regulated. Using matrix-assisted laser desorption/ionization-quadrupole ion trap-time of flight mass spectrometry, three up-regulated spots (tubulin beta chain, tropomyosin fragment, and actin N-terminal fragment) and two down-regulated spots (actin C-terminal fragment and myosin light chain) were identified. One possible interpretation of the results is that elevated CO₂ weakened contraction of the tube feet muscle through an alteration of proteome composition, mainly associated with post-translational processing/proteolysis of muscle-related proteins.

Planarian myosin essential light chain is involved in the formation of brain lateral branches during regeneration

The myosin essential light chain (ELC) is a structure component of the actomyosin cross-bridge, however, the functions in the central nervous system (CNS) development and regeneration remain poorly understood. Planarian Dugesia japonica has revealed fundamental mechanisms and unique aspects of neuroscience and neuroregeneration. In this study, the cDNA DjElc, encoding a planarian essential light chain of myosin, was identified from the planarian Dugesia japonica cDNA library. It encodes a deduced protein with highly conserved functionally domains EF-Hand and Ca(2+) binding sites that shares significant similarity with other members of ELC. Whole mount in situ hybridization studies show that DjElc expressed in CNS during embryonic development and regeneration of adult planarians. Loss of function of DjElc by RNA interference during planarian regeneration inhibits brain lateral branches regeneration completely. In conclusion, these results demonstrated that DjElc is required for maintenance of neurons and neurite outgrowth, particularly for involving the brain later branch regeneration.