Worm Breeder's Gazette 10(3): 146

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.

Tests for Maternal and Paternal Chromosomal Imprinting

Herbert Haack and Jonathan Hodgkin

Figure 1

Recent work (e.g.  Cattanach and Kirk  1985, Nature 315:496) has 
shown that normal embryonic development in mice (and presumably other 
mammals) depends on correct chromosomal imprinting during 
gametogenesis.  Thus, for example, a euploid mouse that has received 
both copies of chromosome 2 from its mother (MM) does not develop 
normally, nor does the corresponding mouse that has received both 
copies from its father (PP).  Some regions of the mouse genome are 
indifferent to imprinting, some only require maternal imprinting, and 
some only require paternal imprinting.  It is suspected that 
methylation of DNA at key sites provides the molecular basis of 
In view of the current interest in this phenomenon, we tested for 
effects of this type in C.  elegans.  We did not expect to find any 
imprinting, because no phenomenon of this type has turned up during 
other genetic work on C.  elegans, and also because there is no 
detectable methylated cytosine in C.  elegans DNA.  Also, work with 
nondisjunction mutants had shown that there is no imprinting of the X 
chromosome: both hermaphrodites and males are perfectly normal if they 
derive their X chromosome(s) only via oogenesis or only via 
spermatogenesis (Hodgkin, Horvitz & Brenner 1979).  This work also 
demonstrated (using the generalized nondisjunction mutant, him-6(e1423)
) that at least some of the MM autosomal exceptions could be recovered.

Crosses to detect the ten possible autosomal exceptions were carried 
out, again using him-6 to generate disomic or nullisomic gametes.  In 
all ten crosses, several exceptional animals of the appropriate 
genotype were recovered and checked by progeny testing.  These animals 
appeared to be as viable as their siblings.  We conclude that there 
are no obvious imprinting effects at the level of individual 
chromosomes in this species.  It remains possible that a wholly 
matroclinous or wholly patroclinous euploid embryo might develop 
Crosses are listed below.  All animals were homozygous for him-6(
e1423).  Other alleles bli-4(e937), ), 
0), 99), 282),
91), 24).[See Figure 1]

Figure 1