I am guessing the point of:

  my @b = split(/[.]/,$a);
  my $OrginalBlast;
  $OrginalBlast = $b[0].".".$b[1].".".$b[2].".".$b[3].".".$b[4].".".$b
+[5].".".$b[6].".".$b[7];
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is to remove unwanted elements from the end of $a. It must have 9 or more elements separated by periods, and only 8 are wanted. There are better ways to achieve this, among them:

  $OriginalBlast = join '.', split(/[.]/,$a)[0..7];
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or

  ($OriginalBlast) = $a =~ m/(([^.]+\.?){8})/;
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