SUDDEN-DEATH OF CHICKEN EMBRYOS WITH HEREDITARY RIBOFLAVIN DEFICIENCY

Riboflavin-binding protein (RfBP) mediates the deposition of riboflavi n during the formation of eggs in birds. Hens of a strain of Single-Co mb White Leghorn chickens, which are genetically unable to produce RfB P, lay eggs containing insufficient riboflavin to sustain embryogenesi s beyond 13 or 14 d of incubation. Embryos in these eggs grow normally until the day of death, and their heart rate is normal to within an h our of death. The effects of riboflavin-deficiency first appear after d 10 of incubation when embryos become severely hypoglycemic and begin to accumulate intermediates of fatty acid oxidation. Although the act ivities of flavin-dependent enzymes are reduced generally, the 80% red uction in the activity of medium-chain acyl-CoA dehydrogenase further suggests that the major metabolic consequence of riboflavin deficiency is a severe impairment of fatty acid oxidation. The riboflavin-defici ent strain provides numerous insights into the metabolism of normal he ns and chicken embryos and may be a useful model for sudden death synd romes in humans.