my @seqList;
my @sequences;
my $dnaString;
my $count = 0;

my @DNA = <DATA>;
foreach my $line (@DNA) {
	if ($line=~/^>(\S+)/){
		push (@seqList, $1);
		push (@sequences, $dnaString) if $count++;
		$dnaString = '';
	}
	else {
		chomp $line;
		$dnaString .= $line;
	}
}
push (@sequences, $dnaString); # need to push last one

__DATA__
>123 blah
abcdef
ghijkl
>456 de dah
mnopqr
>789 nothing wanted here
stuvwxyz


# OUTPUT
@seqList = (
          '123',
          '456',
          '789'
        );
@sequences = (
          'abcdefghijkl',
          'mnopqr',
          'stuvwxyz'
        );