Worm Breeder's Gazette 12(1): 25 (September 1, 1991)

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.


Lawrence A. Schriefer, Robert H. Waterston

Department of Genetics, Washington University. St. Louis, MO 63110.

Several dominant mutations in the actin gene cluster, act-1 ,2,3LG V, have been identified in the course of our studies on mutants affecting body wall muscle structure. These mutations, either heterozygous or homozygous, lead to abnormal placement of actin and decreased motility. Pharyngeal muscle structure and function are abnormal in homozygotes; in some mutations, this pharyngeal muscle dysfunction is associated with early larval lethality.

With the recent solution of the actin crystal structure (Kabsch et al. Nature 347 :44), our interest in these mutations was rekindled. To determine what portion of the actin molecule might be altered in these dominant mutations, we have begun to sequence them. Genetic mapping has not resolved which of the three actin genes are altered by these mutations, but analysis of revertants suggested that the mutations were likely to be in either act-1 or act-3 .We have used the polymerase chain reaction (PCR) to recover the mutant genes from the homozygotes and transformed clones were grown up and used as the sequencing template. The sequence of each of the genes was then obtained using primers spaced along the gene. To date we have identified seven missense mutations.

Residue Changes in Mutant Actin Genes

1. Dominant mutations; homozygous viable

st 15 Tyrosine to Asparagine at residue 143 in gene 3

st 22 Glutamate to Lysine at residue 334 in gene 3

2. Dominant mutations: homozygous inviable

st 119 Lysine to Threonine at residue 18 in gene 1

st 120 Aspartate to Asparagine at residue 11 in gene 1

3. Dominant mutations; homozygous inviable; in an actin gene 3 deletion background

st 272 Glycine to Arginine at residue 168 in gene 1

4. Pharyngeal muscle only; dominant mutation; homozygous inviable (Courtesy of Leon Avery)

ad 468 Proline to Serine at residue 245 in gene 2

ad 468 Serine to Phe. at residue 265 in gene 3