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Luca Comai comai at U.WASHINGTON.EDU
Wed Sep 4 15:18:55 EST 1996

Dear Network,

The definitions of orthologue and paralogue make better
sense if one considers the root of the these two words:

ortho means "upright, straight" and, thus, "correct, right, true to the
para means "on the side, beyond" and, thus, "duplicated, possibly

Consider, for example, orthodox and paradox: the first refers to the
"right opinion" while the second refers to "apparently wrong opinion or
phenomenon".  According to the general usage of ortho and para,
orthologues must refer to similar genes having the same function in
different taxa, such as LEAFY in Arabidopsis and FLORICAULA in snapdragon.
Paralogues, such as in AP1 and AGAMOUS, must instead result from
duplication and can be functionally divergent.  By the way, I think that
both words could end in -logue or in -log.  But, more importantly, are my
orthodontics feeling parallel today or am I undergoing a paranormal


Luca Comai
Department of Botany, Box 355325
University of Washington, Seattle, WA 98195-5325

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