CHARACTERIZATION OF TERMINALLY DIFFERENTIATED CELL STATE BY CATEGORIZING CDNA CLONES DERIVED FROM CHICKEN LENS FIBERS

To characterize a terminally differentiated state of cells at the gene expression level, a cDNA library of chicken lens fibers was analyzed. The major population of the library consisted of cDNAs encoding delta -crystallin (about 35% of the recombinants) and other crystallins (alp ha A-, alpha B-, beta A3/A1-, beta B1-, beta B2-), as well as cytoskel etal proteins (CP49, CP95), and membrane protein (MP28). These cDNA cl ones representing lens structural proteins known, accounted for about 60% of the library. When 96 clones were randomly selected from this li brary, 55 clones corresponded to the above-mentioned major class prote ins. Analyses of the remaining clones indicated that many of them were expressed in a lens-specific manner at very low levels. The partial n ucleotide sequence analysis of these clones revealed that two cDNAs co rresponded to the genes encoding lens-type connexin, three cDNAs to th e genes encoding housekeeping proteins, and some cDNAs to the genes en coding regulatory proteins. The mRNA composition in the chicken lens f iber cells indicated rather simple organization of mRNA species of thi s cell type, and gave scope to the possibility of full description of differentiated lens fiber cells at gene activity level.