This tool uses the maize
Recombination Nodule map (Anderson et al.
to calculate approximate chromosomal positions for loci given a genetic
map for a single chromosome. To run the calculator on your own machine,
visit the download page).
How To Submit Your Own Map Data:
Your map data MUST include the following:
(1) Your map must consist of a number of lines. Each line should start
with the name of the locus, followed by a tab, followed by the
cytological or centimorgan value for that locus.
(2) The program assumes that the tip of the short arm for genetic maps
is at 0.0 cM UNLESS you submit a locus with a cM value of less than
zero; it assumes that the tip of the short arm for a cytological map is
(3) The program also assumes that the tip of the long arm on genetic
maps is at the cM value of your highest submitted cM value. So, if you
believe that the tip is not exactly at this locus, you should add a tip1
locus at the end with the cM value of where you believe the tip to be.
(4) There must be ONE locus beginning with the characters "cent" for all
maps (on cytogenetic maps, this would likely be with a coordinate of 0;
it is needed to mark the separation between short and long arm). The
program will assume that this is the centromere.
(5) For cytogenetic maps, your loci must be in order starting
with the tip of the short arm.
Here is a genetic map sample set to use while experimenting. Assume
that this set is for chromosome #1.
... and here is a cytogenetic sample for chromosome #9:
umc109 (CBM 9.01) 0.79
bz1 (CBM 9.02) 0.65
wx1 (CBM 9.03) 0.13
csu54b (CBM 9.08) 0.95
Note About Conversion Factor: Entering a
number in this box causes the resulting genetic map to be amplified by
that factor in order to aid in matching the output to other genetic maps
you may have.
Comments or questions? Send an email to Carolyn Lawrence at