Terminal differentiation in the avian uropygial gland. Accumulation of fatty acid synthase and malic enzyme in non-dividing cells.

The secretory tissue of the uropygial gland is of the holocrine type, containing both dividing progenitor cells and lipid-filled differentiated cells. In this study, we examined the relationship between cell division and differentiation. The location of dividing cells was determined by autoradiography of tissue sections from ducklings injected intra-abdominally with 3H-thymidine.

Malic enzyme and fatty acid synthase in the uropygial gland and liver of embryonic and neonatal ducklings. Tissue-specific regulation of gene expression.

Malic enzyme [L-malate-NADP oxidoreductase (decarboxylating), EC 1.1.1.

Molecular cloning of cDNA sequences for avian malic enzyme. Nutritional and hormonal regulation of malic enzyme mRNA levels in avian liver cells in vivo and in culture.

A double-stranded cDNA library constructed from the total poly(A+) RNA of goose uropygial gland was screened for recombinants containing sequences complementary to malic enzyme mRNA. Replicate arrays of 1400 colonies were hybridized independently with 32P-labeled cDNAs copied from two populations of hepatic RNA derived from tissues which differed by about 35-fold with respect to the relative synthesis of malic enzyme. Forty-eight of the colonies which gave differential signals were further screened by hybrid-selected translation.

Molecular cloning of gene sequences for avian fatty acid synthase and evidence for nutritional regulation of fatty acid synthase mRNA concentration.

A double-stranded cDNA library was constructed using total poly(A)+ RNA from the goose uropygial gland. Clones containing sequences complementary to fatty acid synthase mRNA were initially identified by colony hybridization with a 32P-labeled cDNA transcribed from RNA enriched for fatty acid synthase mRNA. Identity of the fatty acid synthase clones was confirmed by hybrid-selected translation.