Differentiation of chick embryo cerebral hemispheres: a critical evaluation of a bulk preparation of neuroblasts and spongioblasts.

Abstract

Abstract— A critical evaluation of a previously described method of bulk preparation of neuroblasts and spongioblasts from chick embryo cerebral hemispheres furnished the following results. A major loss of total RNA occurs during the preparation of the cell fractions. The loss occurred mainly during the dissociation of the tissue and the following centrifugations. The missing RNA's were found in the supernatants after cell centrifugation at low speed. There was a selective loss of transfer RNA amounting to 70–80 per cent relative to ribosomal RNA. The relative proportions of the 29, 18 and 5s ribosomal RNA's were constant, but there was a decrease in their proportion relative to heavy‐molecular weight, rapidly‐labelled nuclear RNA. The ribosomal RNA's in the low‐speed supernatant could be resedimented at 35,000 g whereas most transfer RNA could not. The results are consistent with a loss of fragments of cytoplasm containing ribosomes and with additional extraction of transfer RNA during the preparation.