Worm Breeder's Gazette 8(3): 25

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.

Mosiac Analysis of ace-1

B. Herman, C. Kari

The single ace-1+ gene present on a free duplication in an otherwise 
homozygous ace-2 I;ace-1 X genetic background is responsible for 
coordinated animal movement and acetylcholinesterase activity in the 
regions of the nerve ring and ventral and dorsal nerve cords.  We have 
found that gentle squashing of these animals followed by freezing in 
liquid nitrogen, popping off of the coverslip and then fixing and 
staining according to Culotti et al.(1981 Genetics 97: 281) gives 
reliable staining of both cords and the ring.  We have used animals of 
genotype ace-2 I; unc-93 III; unc-3 sup-10 
f) (where the duplication carries the 
wild-type alleles of all four X linked markers) to select specifically 
for genetic mosaics in which mnDp14 was lost at P1.  These animals are 
non-Unc-3 and non-Daf (normal FITC staining) because the duplication 
is retained in the AB lineage; they are non-Unc-93 in movement and egg 
laying because all muscle cells but one lack sup-10+; and all of their 
progeny are Unc-3 because the duplication is not present in the germ 
line.  They also show the Ace-Unc phenotype and the absence of 
histochemical staining for acetylcholinesterase characteristic of the 
homozygous ace-2;  This indicates that one or 
more descendants of P1 are primarily responsible for both properties 
of ace-1+ that we have followed.
We have used animals of genotype ace-2 I; unc-3 
ace-1 X; mnDp14(X;f) to select for Ace-Unc non-Unc-
3 progeny produced through somatic duplication loss.  (This method 
precludes the possibility of detecting losses occurring at either AB 
or ABp because duplication loss by either of these cells generates an 
Unc-3 phenotype, which is epistatic to Ace-Unc.) Ten were found and 
all were missing the duplication from their germ lines.  This result 
indicates that in order to produce an Ace-Unc phenotype by a single 
event of duplication loss, the loss must usually occur in a germ line 
precursor cell, i.e., P1-P4.
We have also looked at the consequences of losing ace-1+ from cells 
of the AB lineage and obtained results consistent with the above 
experiments.  First, we were unable to find Ace-Unc progeny of ace-2 I;
daf-6 odites that had retained 
the duplication in their germ lines.  Such animals should have been 
found if duplication loss at AB, for example, gave an Ace-Unc 
phenotype.  We have also used the daf-6 marker to select specifically 
for loss of the duplication at either ABp or AB in ace-2; 
ace-1;   The results 
showed that an animal in which ace-1+ is missing from all descendants 
of ABp (which is precursor to 74 of 75 cord motor neurons) has normal 
movement and normal enzyme activity in the ring and cords.
When the above results are considered in light of the known cell 
lineages, it is difficult to escape the conclusion that the effects of 
ace-1+ on coordinated movement and acetylcholinesterase appearance in 
these animals are very likely due, at least primarily, to gene 
expression in muscle cells.  Since it is likely that ace-1 is a 
structural gene for the enzyme (Johnson et al.  1981 Genetics 97: 261),
the obvious suggestion is that the enzyme is synthesized by the 
muscle cells and is then localized in the regions of the muscle arms 
that make neuromuscular junctions (which are in the nerve ring and the