Worm Breeder's Gazette 4(1): 34

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.

Characterization of ts Embryonic-arrest mutants of C. elegans (G set)

E. Isnenghi, R. Cassada, M. Culotti, J. Miwa, E. Schierenberg, G. von Ehrenstein

Figure 1

We are characterizing a number of ts lethal mutants, isolated 
following EMS mutagenesis (WBG vol. 2  Nr. 1  p.  13).  We have used 
standard mutagenesis conditions, except that we have found synchronous,
just-hatched L1's convenient for mutagenizing.  We found they are 
reproducible, uniform, and reliable targets, perhaps as a result of 
uniform germ-line and cuticle configurations.  Besides being easily 
obtainable, hatchees can be stored frozen in liquid N2 (using 
Brenner's glycerol method) with over 50% thawing survival.  Post-
thawing fertility is comparable to that of unfrozen animals both for 
mutagenized and unmutagenized animals.  This provides many batches 
over an indefinite period of time from a standard mutagenesis.  
Moreover, freezing avoids the hazard and any variabilities due to 
repeated mutageneses.
About 3.0% of the F2 clones tested were ts lethals (whether the EMS 
came from Sigma, Pierce, or Eastman).  About half (155) of the total 
isolates were independent mutants, and of these, 36% (56) showed some 
percent of arrested embryos at 25 C.  About half of these show nearly 
100 % embryonic arrest in at least one shift to 25 C (L1, L4 or adult).

These last have all been backcrossed twice and retested; all 
appeared to be recessive, based on segregation frequencies from 
backcrosses.  Postbackcross data to date for the best characterized 
mutants are summarized below.
Definitions to the 
- = at 16 C no differences to wt 
- = at 25 C only EMB phenotype 
a) Stage of arrest after continuous exposure to 25 
LB = lima bean to tadpole stage, (abnormal morphology)
CO = comma 
LO = loop 
EP = early pretzel 
PR = pretzel 
b) TSP = as defined by Suzuki (1970)
c) EMSt = abnormal EMSt division, sister cells round off 
DIV = overall division rate, - = slower, + = faster than wt 
GAS = defective gastrulation (time and direction of E-cell division 
and E-cell migration abnormal) 
PLA = Strong cytoplasmatic streaming starting in one-cell stage 
wt->100 = cell lineage identical to the wild type up to 100 
2E4 = asynchronous division from 2 to 4 E-
d) L4's shifted 
Growth at 16 C is normal in all cases; visible phenotypes were not 
detected except for G20, which is UNC at 16 C and 25 C.  Linkage data 
are based on segregation from at least 6 markers (all 6 linkage groups)
for each mutant.  Parental effect and complementation data are also 
available for some mutants.
[See Figure 1]

Figure 1