Journal of Neuroscience, Vol 7, 2433-2444, Copyright © 1987 by Society for Neuroscience
Developmentally regulated rat brain mRNAs: molecular and anatomical characterization
FD Miller, CC Naus, GA Higgins, FE Bloom and RJ Milner
In order to identify markers for developing neural cell populations and
gain molecular insights into the processes of neural development and
differentiation, we have selected cDNA clones of rat brain mRNAs that are
expressed in brain at embryonic day 16 (E16) with at least 10-fold greater
abundance than they are in adult brain. Eleven such clones were obtained
from a cDNA library of E16 brain poly(A)+ RNA using a combination of
differential and subtractive hybridization screens. The temporal and
spatial patterns of expression of the mRNAs corresponding to these clones
were characterized by Northern (RNA) blotting and by in situ hybridization.
Although all the mRNAs were enriched in embryonic brain, different mRNAs
demonstrated maximum abundance at different times in late embryogenesis.
The mRNAs can be grouped into 3 classes on the basis of their patterns of
spatial expression in the embryo: one cDNA clone from each class and its
corresponding mRNAs have been characterized in more detail. Class C
represents mRNAs that are highly enriched in the nervous system and may be
expressed in newly differentiating neurons; the example chosen was shown by
nucleotide sequence analysis to encode the brain alpha 1 isotype of
tubulin. Class B mRNAs have a broader distribution in the developing embryo
but are expressed predominantly in the ventricular germinal zones of the
developing nervous system and may represent molecules involved with
neurogenesis. A third class (Class A) includes mRNAs with a more
homogeneous distribution within the embryo and developing nervous system,
which may encode "housekeeping" molecules. These clones and their encoded
products will provide markers for cell populations at particular stages of
neural development.