Worm Breeder's Gazette 1(2): 16

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.


D.B. Dusenbery

The group of mutants previously described (Genetics 80: 279, 1975) 
by Sheridan, Russell and myself have been further characterized.  
Additional complementation tests indicate that RS2 and RS7 belong to 
the same group as DD79, that DD72 and DD75 complement with all other 
groups including one another.  RS3 and DD76 remain unclassified.  
Sixteen of these strains have been tested for their chemotactic 
responses in 11 different tests.  The six strains belonging to the 
complementation group of DD79 have similar patterns of responsiveness. 
This pattern is a nearly normal response to C02 in pH 6.0 phosphate 
buffer, to acid, and to pyridine and little if any response to Na+, Cl-
, OH-, CO2 in pH 8.8 borate, cAMP, and D-tryptophan.  A particularly 
interesting observation is that three other strains (representing at 
least two different complementation groups) avoid cyclic AMP instead 
of being attracted.  All but two of the 16 strains had substantial 
responses to C02 in phosphate and to acid.  Most strains were 
defective in most other tests.  Recently I tested two of Don Riddle's 
dauer-defective mutants (E1378 and E1382) they also demonstrated 
relatively normal responses to C02 in phosphate and to acid.  This 
observation prompted me to test the Caltech chemotaxis mutants for 
defective dauer production.  Initial results indicate that RS4 and 
DD71 do not make dauer larvae in normal numbers and that DD73 makes 
dauers even in the presence of bacteria.  Thus it looks like lack of 
chemotaxis to NaCl and defective dauer production select for much the 
same kind of mutants.  I hope to collect a much different set of 
mutants by selecting for those defective in avoidance of acid or C02 
in phosphate.
We have recently discovered that the worm avoids mM concentrations 
of glucose, fructose, and mannose.  Experiments to further define the 
specificity are in progress.
1.  Does anyone have suggestions as to the possible adaptive 
significance of the chemotactic responses such as attraction to ions 
or pyridine and avoidance of D-tryptophan or certain hexoses?
2.  Is anyone presently working on the identification of 'natural' 
chemical stimuli such as those in bacterial cultures?