POSTEL, Ute; THOMPSON, Fiona; VINEY, Mark; BARKER, Gary; WEBSTER, Simon; MORRIS, Steve*; University of Bristol, U.K.; University of Bristol, U.K.; University of Bristol, U.K.; University of Bristol, U.K.; University of Wales – Bangor, U.K.; University of Bristol, U.K.: Red crabs on the run: molecular bases of the seasonal migration of Gecarcoidea natalis
The terrestrial crab Gecarcoidea natalis retains a marine larval stage and on Christmas Island undertakes an annual breeding migration to the coast. The monsoon rainfalls stimulate a near instantaneous switch from hypo- to hyperactivity. How this switch is accomplished and controlled is unknown. We examined changes in gene transcription in the leg muscle. Total RNA of tissue from migrating and non-migrating male G. natalis was used to construct two cDNA libraries. First recombinant clones were isolated and insert fragments amplified and sequenced. About 73 % of the ESTs could be assigned to known sequences held in databases using BLAST and contig analysis. Approximately 57 % of the ESTs match proteins related to muscle function. Comparison of sequence frequencies of the libraries revealed differential expression of several genes with the change in physiological states. For example, actin was significantly less transcribed in migrating crabs, which could either indicate a rise in general gene expression during migration and/or might be related to basic changes in the muscle structure. Further indications for migration related structural changes of the muscle tissue are the increase in the transcription of a muscle LIM protein and of a protein with highest similarity to tropomyosin. Ongoing sequencing work is expected to reveal differential expression of genes in addition to those for muscle structural proteins. Specific and key differences between the libraries will now be confirmed by RT-PCR. This non-specific approach to detect physiological differences appears to be an appropriate tool for large scale screening for transcription based changes supporting the physiology of seasonal ecology and behaviour of this crustacean.
