Characterization of an Antiserum against Feather Keratins of the Chick: Its Crossreaction with a Lens Protein, δ-crystallin

We prepared an antiserum against a fraction of solubilized keratins extracted from down feathers of newly hatched chicks. The specificity of the antiserum was tested by double immunodiffusion, immunofluorescent staining, and immunoblotting after sodium dodecylsulfate-polyacrylamide gel electrophoresis. All the bands except "Fast protein" reacted with the antiserum, suggesting the presence of a common antigenicity through various polypeptides in solubilized feather keratins. Delta-crystallin, which is a lens specific protein, also reacted with the antiserum. The presence of a common antigenicity between δ-crystallin and feather and scale keratins was confirmed by affinity-purification of the antiserum, and its significance is discussed.     

Induced formation of ribulose 1,5-diphosphate carboxylase in Rhodopseudomonas spheroides with particular concern to its relation with chromatophore formation

A comparative study was made on features of the induced synthesisof RuDP carboxylase in three strains of R. spheroides with differentbiochemical properties. In strains Sb and Sa, which were able to grow under either light-anaerobicor dark-aerobic conditions, activities of RuDP carboxylase inthe light-grown cells were much higher than those in dark-growncells. The level of RuDP carboxylase activity in dark-growncells of the Sb strain (wild type strain) increased two to threetimes in the dark by incubating the heavy cell suspension underlow aeration, but, for a further increase in enzyme activity,a light-anaerobic condition was required. This is in contrastto the induced formation of bacteriochlorophyll which has beenshown to proceed actively in the dark as well as in the light.On the other hand, with dark-grown cells of the Sa strain, whichhad possible partial defects in the chlorophyll synthesis system,the induced synthesis of RuDP carboxylase under the light-anaerobiccondition was markedly retarded as compared to that with theSb strain. RuDP carboxylase formation was not induced in L-57(a colorless mutant) under any of these conditions. The induced formation of RuDP carboxylase, as well as of bacteriochlorophyll,under the light-anaerobic condition was considerably suppressedby hydroxyurea and mitomycin C. This suggests that the geneticcontrol systems of RuDP carboxylase synthesis may be closelyrelated with those for the formation of the photosynthetic apparatus. ¹This work was supported in part by Public Health Research GrantAM 08016 from the National Institute of Arthritis and MetabolicDiseases, U.S.A. (G. K.). ²Present address: Laboratory of Radioisotope Experiment, TohokuUniversity School of Medicine, Sendai, Japan. (Received September 6, 1968; )