Setting the Numbering Origin

Preserving sequence numbering is particularly useful if you want to work on a smaller more manageable region of a large chromosome but wish to retain the original numbering. When you copy a section of a larger sequence and paste the copy into a new MacVector sequence window (or use FILE | NEW FROM CLIPBOARD), the original numbering is retained.


  • Open pBR322 (in the SAMPLE FILES folder in the MacVector application folder).
  • Either:
    • in the EDITOR tab select the Features popup menu and select the tetracycline resistance CDS.
    • or

    • click on the TET feature in the MAP tab.

    This selects the region from 86 to 1276 in both the EDITOR and MAP tabs.

  • Now choose Edit | Copy, followed by File | New from Clipboard. A new window appears with the numbering origin set to 86. (You can also accomplish this by choosing File | New | Nucleic Acid and then Edit | Paste into the new window).
  • If you want to quickly reset the origin to “1”, you can right-click (or -click ) in the sequence area to bring up a context sensitive menu and choose Reset Origin to 1.
  • Changing the numbering of existing sequences

    You can also easily change the numbering of a sequence by selecting then dragging the small red cross that usually appears at the beginning of the sequence.
    Dragging the cross to another location designates that as the “plus 1” residue – all residues before that position will be given negative numbers.
    You can also set the first residue to a positive number. To set this, double-click on the red cross and enter a new start value in the sheet that appears.

    Screenshot 2023 03 01 at 14 00 53

    Setting the Circular Origin

    If you are working with a circular sequences then you can change the location where the sequence is “split” in the editor.

    you can just right click the sequence and set SET CIRCULAR ORIGIN from the context sensitive menu that will appear. This also changes the Map tab so that the new position is located at 12 o’clock.

    In the MAP tab you can also select a restriction enzyme site and right- click to choose Set Circular Origin.

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