I am running blastn, blastx and tblastx searches on NCBI's nt, est, nr and HTGS databases using transcriptome data containing ~56,000 contigs. I have been able to produce biopython scripts to run these searches with only non-matching blast queries retrieved. Now I would like to retrieve blast queries which only show hits in the taxon 'caudata' i.e.protein-coding transcripts unique to urodeles. Is there a specifc boolean query I can put in the entrez query parameter of the qblast function which will perform this? Or will I have to do something more intensive such as perform the search specifc to each taxon and find the queries which only have hits in the caudata taxon.
Thanks for any help,