J. Liu et Am. Fallon, Effect of nutrient deprivation on ribosomal RNA and ribosomal protein mRNAin cultured mosquito cells, ARCH INS B, 46(1-2), 2001, pp. 64-72
The effect of nutrient deprivation on RNA and protein synthesis in cultured
Aedes albopictus mosquito cells was investigated by replacing the culture
medium with phosphate-buffered saline. After a 2 h starvation treatment, in
corporation of radio-labeled precursor into total RNA was inhibited by 50%,
and after 4 h, incorporation of amino acids into protein was inhibited by
50%. To investigate directly the effects of starvation on rRNA synthesis, r
ibosomal subunits were prepared from treated cells by sucrose density gradi
ent centrifugation. After 4 h in saline, incorporation of [H-3]uridine into
ribosomal subunits had declined to baseline levels. Even after 8 h starvat
ion, however, the effect was reversed by refeeding with complete medium, in
which cells resumed rRNA synthesis and ribosomal subunit assembly. During
8 h starvation, total amounts of rRNA detected by northern blot remained st
able. Ribosomal protein mRNA abundance was measured on northern blots, usin
g probes corresponding to L8 and L31 ribosomal protein genes. The content o
f these ribosomal protein mRNAs was unchanged during starvation, or during
treatment with actinomycin D. These results suggest that ribosomal protein
mRNAs belong to a long-lived mRNA population, and suggest that post-transcr
iptional regulation of ribosomal protein synthesis is an important regulato
ry mechanism in growing mosquito cells. (C) 1998 Wiley-Liss, Inc.