accession numbers

[Brian Foley]

Vozier wrote:
>... I'm currently trying to perform a
> phylogenetic analysis based on rbcL (for the large 
> subunit of Rubisco) gene
> sequences. I have some sequences, but need some 
> more to give the analysis more
> strength.

	Keep in mind that the more sequences you
have, the more computationally intensive the analysis
becomes.

>          The problem I have is obtaining rbcL sequences 
> of green algae. 
> ... In fact, sequences
> wich I know exist and have personally retrieved from 
> genbank do not appear in the search results.

	I have found that the best way to retrieve
a great many sequences from GenBank is to do a BLAST
search with my gene of interest.  Not only do I get
the accession numbers for many homologs and related
genes, but they are also ordered by percent similarity
(at least in an ungapped alignment).
	For information, send a message to 
blast at ncbi.nlm.nih.gov  with "help" as the
body of the e-mail message.  There are also other
similar search engines available, but BLAST is a 
good place to start.

Brian Foley
HIV Sequence Database