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.
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 table: - = at 16 C no differences to wt detected - = at 25 C only EMB phenotype detected a) Stage of arrest after continuous exposure to 25 C LB = lima bean to tadpole stage, (abnormal morphology) CO = comma stage LO = loop stage EP = early pretzel stage PR = pretzel stage 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 cells 2E4 = asynchronous division from 2 to 4 E- cells d) L4's shifted up 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]