Worm Breeder's Gazette 7(2): 30

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.

Cloning of an Adult Hermaphrodite-specific Gene Family

T. Blumenthal, W. Sharrock, M. Squire, J. Spieth, S. Kirtland

We have cloned a small family of developmentally-regulated genes 
from C.  elegans.  The timing of expression and abundance and size of 
the mRNA suggest that these genes code for the recently-identified 
yolk proteins.  The genes were cloned by selecting the most abundantly-
expressed sequences from a C.  elegans cDNA library in pACYC184.  At 
least 40 such clones, selected solely on that basis, are members of a 
single family of related genes.  Like the yolk proteins, these genes 
are expressed abundantly in adult hermaphrodites but apparently not at 
all in adult males or in larvae.  Thus they appear to be controlled at 
the level of transcription.
The gene family containing five genes, based on genomic Southern 
blots.  Genomic clones have been selected from John Karn's lambda1059 
libraries.  So far we have isolated four genes from the lambda 
libraries.  All four are between 5 and 6 kb in length and all 
hybridize to a single RNA species about 4.7 kb in length on Northern 
blots of adult hermaphrodite RNA.  This is approximately the right 
length to code for the largest of the yolk proteins.  One of the genes 
has been analyzed in more detail.  It is 5.1 kb long and contains only 
two or three small (0.1-0.3 kb) introns.
There are two sub-families based on cross-hybridization and 
restriction maps.  Two of the genes are so similar that they hybridize 
nearly as well to each other as each does to itself.  Furthermore, of 
the eight restriction sites found within each of these genes, six are 
found at homologous sites within the other gene (including one within 
an intron).  The other sub-family, is composed of three genes.  Two of 
these genes have been cloned and are linked in tandem, with only about 
2 kb of DNA between the 3' end of one and the 5' end of the other.  C. 
elegans Bergerac has an extra 1.7 kb of DNA between these two genes 
and we are now in the process of mapping the location of the genes on 
the chromosome using this heterogeneity.  These two genes are so 
closely related to one another that we have found no restriction site 
differences between them.
The members of one sub-family also cross-hybridize to the members of 
the other sub-family but the hybridizations are much weaker than 
within a sub-family.  Nevertheless some restriction sites appear to be 
shared between the two sub-families.