How to choose the candidate microRNAs from the list? - (Jul/11/2006 )

Hello, Everyone!
I am a newbie in the field of microRNA. Here, I want to ask two questions about how to choose the candidates from the putative microRNAs list.

Two months ago, I searched the miRNAs that can hit the one gene and got a list of 17 miRNAs on Sanger microRNA-database website. However, after did the same thing yesterday, I got a list of 29 miRNA. When compare these two search results, I found that 2 miRNAs drop from the latter list and 14 new miRNAs appear in the latter list.

So my questions are:
1). What cause this change between these two lists?

2). how to choose the candidates from the putative microRNAs list? It will be too time-consuming to finish all the 29-putative miRNAs. Maybe 5 candidate miRNAs will be a good start.
Spending too much money will really drive my boss crazy!

I am eager to get your guys' great help!

A lot of the miRNAs in mirBase are putative predictions of miRNAs. So, choosing the right miRNAs out of the 29 will be difficult with out previous experimental data. Its not clear for every candidate where and in what abundance the miRNAs will be found accross tissues, etc.

I recently heard about a database for mirna that includes data sources for those mirna's and targets validated experimentally. However, I haven't been able to find the name of the database during this post. I'll see if I can dig around and find the site. In the meantime maybe another forum member knows... This should help narrow your list if you can cross reference the miRNAs of interest.

So here are some great miRNA resources:

http://www.diana.pcbi.upenn.edu/ - the Tarbase is the db I was describing that had experimentally confirmed targets (scroll down the page)

http://genes.mit.edu/targetscan/ - target prediction

http://pictar.bio.nyu.edu/ - target prediction

Let me know if these are useful...

Thanks a lot!