Worm Breeder's Gazette 7(2): 66

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.

Observation on Dauer Larvae of lin-4/lin-4 and lin-14/lin-14 Genotypes

A. Fodor

Figure 1

Although both lin-4(CB912) and lin-14(MT529) had originally been 
scored as dauer defectives, I found SDS resistant dauer larvae in 
starving populations of both strains.  In case of lin-4 the frequency 
of dauers in a population seemed to depend upon the size of the 
original inoculum.
Being interested in the interaction of lin and dauer constitutive (
daf-c) mutant genes, I constructed double mutant strains homozygous 
for (1) lin-14 and daf-c(daf-1(m40); 70); )
; 72)and 7) respectively; (2) 
lin-4 and daf-c 370); 72) and 
daf-14(m77) respectively, by using szT-1 (Deak and Fodor) and C1 (R.K.
Herman) balancer strains for the proper crosses.
A.  Construction of daf-c/daf-c; szT-1(lon-2++)/+ dpy-8 
(which segregate szT-1/0;daf-c/daf-c males 
for crosses) was made by producing dpy-8 -c 
hermaphrodites and szT-1/0;daf-c/+ males from progeny of the same 
cross; then crossing them with each other and selecting for NonDpy 
NonUnc dauers at 25 C.  (The procedure was a little bit different with 
daf-1 because of the maternal effect.).
B.  Construction of lin-14  szT-1/0;daf-
c/daf-c males were crossed to lin-14/lin-14; m-5+ 
hermaphrodites.  Eggs were collected at 18 C and developed at 25 C.  
Cross progeny could be distinguished from the self not only visually 
but on the basis of progeny test (Lon males segregated from cross 
progeny.) F1s were cloned and kept at 25 C and dauer progeny were 
collected, recovered, cloned and grown at 20 C.  Those which did not 
segregate Lon males were retested for lin-14 and daf-c homozygosity by 
putting respectively early L4 and L1 progeny to 25 C.
C.  Construction of lin-4  szT-1/0; daf-
c/daf-c males were crossed to C1(dpy-10+unc-52)/+unc-4+ hermaphrodites.
F1 males were crossed to CB912 hermaphrodites.  F1s were cloned and 
kept on 25 C.  Those which segregated both dauers and DpyPara1 (but no 
Unc-4) phenotypes were kept.  Dauers were recovered and cloned on 18 C.
From plates which did not contain DpyPara1s, vulvaless animals were 
picked up, cloned and tested for the expression of the daf-c gene.  
All tests were repeated for several generations.  'Egg preps' were 
produced by the hypochlorite method (R. Hecht) from presynchronized 
populations.  Eggs were allowed to hatch in M9 on 25 C.  The L1 
populations were transferred to large NGM plates spread with bacteria. 
Data below came from repeated experiments.
[See Figure 1]
The temperature-induced LinDaf dauers were SDS resistant but 
morphologically a little bit different from starvation dauers.  It was 
not possible to select for higher penetrance of the daf-14 gene in the 
lin-14; on.
In further experiments I studied the response of lin-4 and lin-14 
DRIF (WBG 6, (1:) 25).  Synchronous L1 populations were liquid media 
containing DRIF (a gift from Jim Golden) and 0.2% of bacteria and some 
antibiotics.  Both strain seemed to grow slower than the N2 controls.  
After three days, practically 100% of lin-4s but less than a half of 
lin-14s were dauers.  Some lin-14 worms seemed to be retarded.
CB912 responded to DRIF normally, therefore the relatively low 
frequency of dauers on their starvation plates might be interpreted as 
a decreased production (or release) of the DRIF.  MT529 responded to 
the DRIF in variable way.  It might be interpreted that there are 
cells responsible for or participating in the dauer formation which 
cannot respond to the DRIF (or to some other DRIF-induced 'signal '), 
when lin-l4 is expressed in them making them biologically too old or 
too young to do so.  However, daf-2, 
s seem to be epistatic over lin-
14.  On the other hand, I saw lin-14; growing 
from L2 via dauer larvae to L4 on 25 C.

Figure 1