$dbh=DBI->connect('DBI:mysql:genome', 'u', 'p');
    $sth = $dbh->prepare ("SELECT P.gene_name_M 
            FROM para_n P 
            WHERE P.number_genes_group = 4"); 

    $sth->execute ()

        
    while (@ary = $sth->fetchrow_array ())
    {
	
	foreach (@ary)
	{
#...........rest of code