CHARACTERIZATION OF A NEURAL CREST-DERIVED CDNA LIBRARY

Neural crest cells arise during neurulation in early vertebrate embryos,
migrate extensively, aggregate at specific sites, and ultimately give rise
to a wide variety of different cell types in the adult, including most of
the neurons and glial cells of the peripheral nervous system, endocrine
cells, pigment cells, and much of the connective tissue of the face and
neck. To generate this cellular diversity, it is believed that during and
following migration, different crest cell populations undergo different
sets of developmental restrictions. In this way, the various crest-derived
populations become progressively restricted to either one or another of
these lineages. We wish to understand the molecular nature of these developmental events,
and how they are regulated during development. To this end, we have
generated a cDNA library from mRNA transcripts isolated from a population
of crest-derived cells in the posterior branchial arches (BAs) of avian
embryos. Presumably, some of the transcripts specific to posterior BA
cells mediate developmental events known to be occurring in these cells,
including developmental restrictions, neurogenesis, and cellular
aggregation. We now propose to use this cDNA library to identify such gene
transcripts. To begin, we will determine which neural crest-derived and
non-crest-derived tissues express these transcripts and at what
developmental stages. This will allow us to correlate the appearance of
specific mRNA transcripts with known developmental events. From sequence
analysis of mRNAs which show "interesting" developmental appearances,
peptides will be synthesized against their predicted amino acid sequences
in order to generate antisera for immunocyto-chemical localization studies
of their gene products. We also plan to identify genes which are
coordinately expressed by the crest-derived cells of the posterior BAs in
order to test the hypothesis that these genes share sequence homologies in
their vicinity. These shared sequences may mediate the coordinated
expression of genes, for example, by binding common DNA-binding proteins.
Finally, we hope to identify genes coding for proteins known to be
specifically expressed in the posterior BAs, including a novel intermediate
filament-associated protein--"NAPA-73". This protein is one of the
earliest markers of neurogenesis in both the peripheral and central nervous
systems.