Worm Breeder's Gazette 10(3): 62

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.

Zinc Finger Proteins in Worms?

Dave Pilgrim

In an attempt to identify genes involved in sex determination which 
may be evolutionarily conserved, I have tried looking for a worm 
homologue to mammalian Testis Determining Factor (TDF).  TDF is 
thought to be the 'master' sex-determining locus in mammals.  The 
putative human gene has been cloned (Page et al., Cell 51:1091 [1987]),
and the predicted protein sequence revealed the presence of repeated 
Cys/His 'zinc finger' domains, indicating a DNA binding function.  
There are homologues found on the sex chromosomes of most mammals 
tested.  (The human X and Y homologues are apparently now referred to 
as zfx and zfy, respectively.) A full length TDF cDNA, isolated from a 
human testis library, was kindly provided by Mark Palmer (ICRF, London)
.  This was used at low stringency to probe a Southern Blot of N2 
genomic DNA.  6-7 bands were seen, depending upon the restriction 
enzyme.  The same probe was used to isolate 9 clones from a genomic 
lambda library, kindly provided by Alan Coulson.  Four of the clones 
were chosen for further study.  Two overlap, the other two appear to 
be discrete.  The clones were fingerprinted by Alan Coulson, and 
compared with the physical map.  The two overlapping inserts (CB#DP004,
005) lie on an unmarked contig which has since been localized by Rita 
Fishpool to LG V, using in situ hybridization.  The third clone (DP002)
lies on the rsn-8/myo-2/myb-1/col-9 contig on the right half of X (
although none of these genes has been genetically mapped).  The last 
clone (DP003) has a small insert, and didn't match anything in the 
data base.  The cross-hybridizing regions of each clone are being 
subcloned for further analysis.  So far I have begun characterization 
of the DP004/005 clone.  This insert accounts for three of the bands 
seen on the southern blot.  A fragment of 3.5 kbp, which cross-
hybridizes with the human cDNA, was subcloned, and used to probe a 
Northern Blot.  A band of 3.9 kb was detected in pA+ RNA prepared from 
him-8 worms in L3, L4 and a mixed stage prep, but no band was detected 
in L2 pA+ or in total RNA.  I have not yet looked to see if the 
message is sex-specific.  When this subclone is used as a probe 
against the human cDNA, it cross reacts most strongly to the portion 
of the cDNA coding for 6 of the 'zinc-finger' repeats, as well as some 
nonfinger-coding sequence.  I have begun to sequence this region of 
the DP004/005 clone to see if it also codes for a zinc-finger protein, 
and if so, if it has a role in sex in worms.