Worm Breeder's Gazette 14(4): 37 (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.

IMMUNE DEFENSE OF NEMATODES: Novel members of ASABF family, and their homologs in C. elegans.

Yusuke Kato

Department of Insect Physiology and Behavior, National Institute of Sericultural and Entomological Science, Tsukuba, Ibaraki 305, Japan

                ASABF is an antibacterial peptide in the body fluid of
the intestinal parasitic nematode Ascaris suum [Moore et al., wbg 13(2),
25; Kato, wbg 14(2), 32].  The mature ASABF-alpha (previously designated
as ASABF) of 71 residues is processed from the 93-residue precursor
deduced from a cDNA clone. A  C-terminally flanked four-residue peptide
is thought to be removed in addition to the elimination of a putative
signal peptide by the processing (Kato and Komatsu, J. Biol. Chem., in
press). A cDNA for ASABF-alpha was cloned using three-step PCR
amplification; (1) RT-PCR using the poly(A)+ RNA isolated from the body
walls of the adult female A. suum as templates, (2) 5'-RACE using SL1
primer, and (3) 3'-RACE. In each step, the PCR-products were cloned into
the pGEM-T vector. Recently, further analyses of the clones revealed
three novel cDNA coding quite similar to the amino acid sequence of
ASABF-alpha. They were designated as ASABF-beta, gamma, and delta. The
mRNAs for these four ASABFs (alpha-delta) were detected in an individual
using RT-PCR with specific primers. These results suggest that ASABF
forms a multigene family. However, only the  alpha and delta products
have been so far detected in the body fluid. The physiological
importance of this family formation is under examination.
                Furthermore, the ASABF homologs in C. elegans were
searched. BLAST data base searches revealed significant sequence
identity with a deduced protein from the cDNA sequence, yk150c7, in the
cDNA catalog by Prof. Yuji Kohara. In addition, the protein deduced from
the putative gene, T22H6.5, was found to be a protein most similar to
both ASABF and yk150c7 using the MPsrch data base search. The transcript
for T22H6.5 was detected using RT-PCR with total RNA from mix-stage
worms as templates. The sequencing of the PCR-product revealed that the
splicing deduced by GeneFinder occurred. The analyses of the gene
regulation of T22H6.5 is currently progressing.

Acknowledgement- We thank Prof. Yuji Kohara (National Institute of
Genetics) for permission to cite yk150c7 from his unpublished data.