Worm Breeder's Gazette 9(3): 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.

Sequences Homologous to 5S rRNA in the rDNA Repeat of Meloidogyne arenaria

H. Vahidi, J. Curran, D.W. Nelson, J.M. Webster and B.M. Honda

Figure 1

Plant parasitic Meloidogyne races can be distinguished by 
differences in banding patterns of repetitive DNA sequences observed 
from ethidium bromide stained gels of genomic restriction digests (
Curran, J. et. al., J. Nematology 18: 83, 1986).
Some of the repeat sequences homologous to C. 
8s, 5.8s, and 26s) and 5S DNA.  Surprisingly, 
a C. robe hybridized to the rDNA bands in M. 
arenaria (race B) and M. hapla (race B).
In M. arenaria, two size classes of repeats, 5kb and 9kb, have been 
cloned into pUC 13. The two repeats have similar restriction sites at 
the ends which could suggest common origin. Moreover, we have observed 
a faint ladder of bands below restriction fragments from the center of 
the 9kb repeat. This could represent deletions caused by 
recombinational events in repetitive DNA, and might mimic the 
processes by which the two classes evolved.
Regions homologous to C. S, 265 and 5S DNA 
have been localized (see map). An 800bp region in the 5kb repeat 
contains a sequence >85% homologous to the C.  
DNA, but has no apparent pol III terminator, and is inactive in a C. 
ption extract. We are currently looking 
further at the expression of the rDNA and 5S DNA, and its organization 
in the related M. hapla. For the latter, six different recombinant 
EMBL phage carrying both 55 DNA and rDNA are being analyzed.

Figure 1