@DNA3 = <DNA3handle>;  # read all LINES of file into array
chomp @DNA3;           # remove any and all newlines
@DNA3=split('',join('',@DNA3));  # join('',@DNA3)  join all LINES into one long line
                                 # split('', ...)  split long line into list
                                 #                 of individual characters
                                 # @DNA3= ...      assign list of individual
                                 #                 characters to an array