Final answer:
Select the RefSeq database for your second search to access accurate and up-to-date information for comparing with your BLASTN results.
Step-by-step explanation:
The database you should select for your second search is RefSeq.
RefSeq is a comprehensive and non-redundant database of reference sequences for genes, transcripts, and proteins. It provides a curated collection of sequence records that are updated regularly.
By conducting your second search in the RefSeq database, you can access accurate and up-to-date information to compare with your BLASTN results from the Nucleotide collection database.