Worm Breeder's Gazette 14(4): 40 (October 1, 1996)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
International Institute of Genetics and Biophysics, via G . Marconi 10, 80125 Napoli, Italy - firstname.lastname@example.org
The cuticle is a central element in the structural organization of all nematodes. It is a multi-layered structure functioning as an exoskeleton and protecting the animal from the environment under a variety of conditions. The cuticle is composed of collegen and an insoluble residues named cuticlins. The first two cuticlin genes (cut-1 and cut-2) have been molecularly identified and cloned from Caenorhabditis elegans. We have identified and cloned three cut-1 homologues from the intestinal parasite Ascaris lumbricoides . Partial DNA sequencing revealed that all three genes contain at least a domain corresponding to the middle of exon three of cut-1 of C . elegans. Two of the genes are separated by about 10 Kb and have opposite directions. The other gene comes from a different genomic region or at least from one that is more than 15 Kb away. This latter gene was studied in more details. Using a RT-PCR and RACE protocols we determined the structure of the messenger which is 1687 nucleotides long and is transpliced to SL1. Comparison of 5800 bp of genomic sequence with those of RACE clones shows that the gene contains four exons of 188, 390, 467, and 582 bp. The lenghts of the first, second and third introns are 1906, 378, and 413 bp respectively. The gene codes for a predicted protein of 386 amino-acids. In the RNA from intestine, which is the tissue from which RACE clones were generated, unexpectedly we have found shorter mRNAs with SL1 spliced onto the second and third exons. These shorter mRNAs are almost as abundant as the long one. At present we do not know the functional relevance of these mRNAs CUT-1 of Ascaris lumbricoides , C . elegans and Meloidogyne artiella are respectively 87% and 84% identical at the amino - acids level. Like in C . elegans and in Meloidogyne artiella CUT-1 of Ascaris lumbricoides has a signal peptide. The number and the positions of all cysteine residues are conserved in the three proteins. We have raised antisera in rabbits against a portion of the protein produced in E. coli and have affinity purified specific antibodies. We are using these in western blot and immuno-microscopy experiments to determine the stages and tissues where the protein is present.