Worm Breeder's Gazette 13(5): 46 (February 1, 1995)

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.

G-Protein (gpa) Genes Are Involved in Dauer Larvae Formation.

Richard R. Zwaal, Ronald H.A. Plasterk

Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands

Guanine nucleotide regulatory proteins (G-proteins)are
involved in signal transduction over the cell membrane.
An activated receptor induces a conformational change
in the G-protein, thereby uncoupling the a- and the b-gamma
subunits, which can propagate the signal down to a diversity
of enzymes and ion channels.
Apart from the homologs of the mammalian G-protein a-subunits
Gsa, Goa and Gqa, C. elegans contains at least 3 other a-subunit
genes that cannot be classified as such. These genes are
called gpa-1, gpa-2 and gpa-3 and are all located on LGV
within 2 map units of each other. Transgenic animals carrying
a presumptive dominant mutation in either gpa-2 or gpa-3
form dauer larvae under non-inducing conditions (7percent
and 40percent respectively; Jane Mendel and Paul Sternberg
(WBG 13#1 p.80)).
To obtain animals in which the gpa-genes are inactivated
we isolated mutants with a Tc1 insertion in these genes,
followed by the isolation of Tc1 mediated deletion alleles
(Zwaal etal., PNAS 90 (1993) 7431-7435). Furthermore
we isolated the different double mutants, and the gpa-
1, gpa-2, gpa-3 triple mutant, using PCR to recognize recombinant
chromosomes with linked gpa alleles.
The response of these mutants to a fixed amount of pheromone
(5 to 10 units) at 25C was tested (many thanks to Betsy Malone
and Jim Thomas for help with the assay). Although the gpa-1
deletion mutant shows a slight reduction in response,
this effect is more clear with the gpa-2 and gpa-3 single
mutants. Under these conditions the gpa-2 gpa-3 double
mutant and the triple mutant show drastic response defects,
so that GPA-2 and GPA-3 seem to have (partially) redundant
functions. Since lowering the food concentration, at
constant concentration of pheromone, results in an increase
in the number of dauer larvae formed (for the triple mutant),
the gpa genes do not seem to be involved in the dauer execution
program but instead in measuring the balance between the
concentration of pheromone and food present. We are currently
studying at which site(s) in the genetic pathway these
mutants act by analyzing epistatic interactions with
different daf genes.