title: Degradation of maternal poly(A)-containing RNA during early embryogenesis of an insect (Smittia spec., chironomidae, diptera).
abstract: Eggs of the chironomid midgeSmittia spec. were shown to contain maternal rRNA, tRNA and poly(A)-containing RNA. The ribonucleoprotein spectrum consisted of monosomes, ribosomal subunits, and subribosomal particles, whereas polysomes could be detected only in small amounts. Poly(A)-containing RNA was found in different regions of the RNP spectrum, mainly between 15 S and 60 S. After labelling maternal RNA by feeding tritiated uridine to the larvae, the radioactivity associated with poly(A)-containing RNA accounted for about 4% of the label in the total RNA extracted from newly deposited eggs. About half of the radioactivity in the poly(A)-containing RNA was lost between egg deposition and an advanced blastoderm stage. The loss was accompanied by both a decrease in the size of the poly(A)-containing RNA molecules and a shift of poly(A)-containing RNP particles to less dense regions in sucrose gradients. Comparison with poly(A)-containing RNA synthesized by the embryo indicates that the reduction in size of maternal poly(A)-containing RNA is not artifactual but reflects its degradation after the formation of blastoderm.
authors.affiliation: Biologie I (Zoologie) der Albert-Ludwigs Universität Freiburg, Albertstr. 21 a, D-7800, Freiburg i. Br., Federal Republic of Germany.
authors.forename: Herbert
authors.initials: H
authors.lastname: Jäckle
keywords: Insect embryogenesis; Poly(A)-containing RNA; RNP-particles; maternal RNA