Worm Breeder's Gazette 8(1): 42

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.

Localization of the Ribosomal Genes in Caenorhabditis elegans by in situ Hybridization Using Biotin-Labelled Probes

D.G. Albertson

The site of the ribosomal gene cluster on embryonic metaphase 
chromosomes of Caenorhabditis  mapped by in 
situ hybridization.  The clone pCe7, which hybridizes to ribosomal RNA,
was nick translated incorporating biotin-labeled UTP.  The site of 
hybridization of this probe DNA was detected by a double-layer 
fluorescent antibody technique.  In the wild type, N2 strain of C.  
elegans the ribosomal probe hybridized to one end of two embryonic 
metaphase chromosomes.  In order to determine which linkage group 
carried the ribosomal genes, in situ hybridization was carried out 
with chromosomes from C.  elegans strains carrying cytologically 
distinct translocation or duplication chromosomes.  Linkage groups I, 
II, IV and X were tested in this way.  Since the ribosomal probe was 
found to hybridize to an internal site, rather than to the end of 
mnDp10 (X;I) chromosomes, it was concluded that the ribosomal genes 
are located at the end of the right arm of linkage group I.  The free 
duplication of linkage group I, sDp1 (I;f) also carries the ribosomal 
genes.  The ribosomal genes were not deleted by a deficiency, eDf3 
that includes unc54 and maps to the left of unc-54 I.  Therefore the 
ribosomal genes are probably located to the right of unc-54.
Chromosomes carrying the lethal mutation, let-209 I (Phil Anderson's 
balancer chromosome) displayed smaller hybridization signals than wild 
type, suggesting that these chromosomes carry a partial deficiency of 
the ribosomal gene cluster.
A duplication of the ribosomal genes, eDp20 (I,II) was identified by 
in situ hybridization.  The duplicated ribosomal genes were found to 
be linked to the right arm of linkage group II.