Search

Abstract: The tarantula Chilobrachys jingzhao is one of the most venomous spiders with a specialized organ, venom gland, which synthesizes and secretes the complex and abundant toxin proteins. The components of the venom have been extensively studied. As far as the molecular mechanism of toxin secretion and metabolism is concerned, we still knew a little. To obtain a comprehensive view of function of its venom gland we constructed a non-normalized cDNA library of the venom gland and generated 788 expressed sequence tags (ESTs). All ESTs were assembled into 356 non-redundancy sequences including 85 clusters and 271 singlets, of which 31.4% of total unique sequences belong to secretion protein coding sequences including cystine knot toxins (29.1%) and other secretion proteins (2.3%); 54.0% are similar to common cellular transcripts; and 14.6% have no significant similarity to any known sequences. Annotation of these ESTs revealed some novel possible venom components and cellular processes important for venom gland functions, including protein posttranslation processing, cell motility, protein synthesis, energy supply, etc. This study contains a transcriptome analysis of spider venom gland focusing on its cellular structural and functional aspects, and confirms the very specialized nature of the spider venom gland as toxin producer. [Copyright &y& Elsevier]

Abstract: The bird spider Ornithoctonus huwena is one of the most venomous spiders in China. Its venom has been investigated but usually only the most abundant components have been analyzed. To characterize the primary structure of O. huwena toxins, a list of transcripts within the venom gland were made using the expressed sequence tag (EST) strategy. We generated 468 ESTs from a directional cDNA library of O. huwena venom glands. All ESTs were grouped into 24 clusters and 65 singletons, of which 68.00% of total ESTs belong to toxin-like sequences, 13.00% are similar to body peptide transcripts and 19.00% have no significant similarity to any known sequences. Precursors of all toxin-like sequences can be classified into eight different superfamilies (HWTX-I superfamily, HWTX-II superfamily, HWTX-X superfamily, HWTX-XIV superfamily, HWTX-XV superfamily, HWTX-XVI superfamily, HWTX-XVII superfamily, HWTX-XVIII superfamily) except HWTX-XI and HWTX-XIII, according to the identity of their precursor sequences. The results have predictive value for the discovery of various groups of pharmacologically distinct toxins in complex venoms, and for understanding the relationship of spider toxin evolution based on the diversification of cDNA sequences, primary structure of precursor peptides, three-dimensional structure motifs and biological functions. [Copyright &y& Elsevier]