Worm Breeder's Gazette 1(2): 26

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

unc-87 I - A New Complementation Group Affecting Muscle Structure

A.R. Macleod, R.H. Waterston

The isolation of 2 new mutants E1458 and E1459 has allowed us to 
define a new complementation group and to clear up the anomalous 
complementation reported in the previous newsletter.  The new isolates 
are severely paralyzed with disorganized muscle by polarized light 
microscopy, are fully recessive and are closely linked to dpy-5 I.  
Their strong phenotype allowed easy interpretation of complementation 
tests and while clearly failing to complement each other and E843 and 
E1216, they complement E1214 and E73 of the unc-15 I locus (the 
putative structural gene for paramyosin).
As a result of these complementation tests, we carried out extensive 
mapping by 3-factor crosses of E843, E1216, E1258 and E1259 against 
dpy-5 I and unc-13 I.  All 4 of the putative alleles were shown to map 
between the two markers, to lie 0.6 - 0.7% to the left of unc-13 (2% 
recombination frequency assumed between the two markers).  In contrast 
E73 is less than 0.1% from unc 13.  Additional mapping of the other 3 
alleles of unc-15, E1214, E1215 and E1402 showed these are 0.1% or 
less from unc-13 as well.  Repeat complementation tests performed with 
E843 and E1216 against E1214 showed complementation contradicting 
previous results.  The comparatively weak phenotype of E1216 and the 
semi dominance of E1214 mutation on muscle structure continued to make 
the tests somewhat unreliable.  However, the map data and the other 
complementation tests leave little doubt that E843, E1216, E1258 and 
E1259 comprise a new complementation group - unc-87 I.
In addition, the abnormalities of muscle structure of the unc-87 
alleles seen with polarized light microscopy are different than those 
seen in unc-15 mutants.  Electron microscopy confirm this, for E1216 
has an approximately normal number of thick filaments arranged 
irregularly into sarcomeres.  However, the thin filaments are not 
generally in their normal positions and are found instead in unusual 
places in the cell.  Opposed to this, the unc-15 mutants show a marked 
decrease in the numbers of normal thick filaments, with instead hollow 
filaments present at the ends of cells.  Accordingly, the unc-87 
alleles are being screened biochemically for defects in their filament