The College of Wooster
LONDON, ONTARIO
The University of Western Ontario
We therefore isolated RNAs from staged
premeiotic tassels, from anthers containing meiotic and haploid microsporocytes
and microspores (see the accompanying report for procedures used to obtain
this material), and from anthers containing mature pollen as well as from
shed pollen. RNA was also prepared from spikelets, representing somewhat
coarser staging. We have performed preliminary RNA-Dot and Northern hybridization
studies on these RNAs to detect transcripts of the 18kd clone gene or closely
related sequences. While further work will be required for precise kinetics,
it is evident that transcripts homologous to the small hsp clone
are absent in premeiotic tassels, accumulate substantially during the period
of meiotic prophase with peak abundance during late prophase, and are virtually
undetectable by the time mature pollen is present. These patterns are evident
in the RNA-Dot analyses of Seneca 43 spikelet RNAs and Ohio 43 anther RNAs,
and the accompanying Northern analyses of Ohio 43 RNAs only, as shown in
the accompanying figure. While developmental expression of small hsp
gene in the absence of stress certainly occurs in anthers containing PMCs
of the appropriate stages, it cannot yet be associated with the prophase
meiocytes unequivocally. Further work is planned to refine our picture
of the timing of developmental expression, to identify whether developmental
expression is a property of all or only some of the maize small hsp
genes, and ultimately to determine whether developmental expression is
in fact localized in the meiocyte.
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