mRNAs that don't go away

Lorraine Sohlberg drayage at earthlink.net
Thu Jun 26 10:56:35 EST 1997


I have gotten some odd results when localizing a mRNA in a senescing
tissue and was wondering if you have seen anything similar in
senescing leaves or other tissues.  I have localized the mRNA encoding
an endopeptidase which degrades seed storage protein in cotyledons of
bean during germination.

My observation is that the endopeptidse mRNA remains at high levels
even in cells that appear to be collapsed and have very little
cytoplasm and have been thought to be dead due to their lack of
staining with tetrazolium which detects activity of basic enzymes of
respiration. It is strange to me that this message would not be
degraded by RNAses in the senescing cells. Have you observed any long
lived mRNAs in senescing cells? Do you know of anyone else doing work
on senescing tissues who might have observed patterns of RNA
accumulation?

I had known from Northerns that this message was abundant in
cotyledons that were shriveled and depleted of storage protein, but I
did not expect the message to be concentrated in the cells which
appeared collapsed.

This endopeptidase appears to be specific to the senescing cotyledon
in bean. I had been curious if this endopeptidase would also be
expressed in senesing leaves, nodules and pods and did westerns and
northern blots on samples from these tissues and did not see any
expression.



If you have any ideas, please e-mail or call me.

Thanks, Lorraine Sohlberg, lorraine at nature.berkeley.edu





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