No abstract

Cadmium (Cd), a highly toxic heavy metal, is distributed widely in the general environment of today. The characteristic clinical manifestations of chronic Cd intoxication include renal proximal tubular dysfunction, general osteomalacia with severe pains, and anemia. We have recently reported that the serum level of erythropoietin (EPO) remained low despite the severe anemia in patients with Itai-itai disease, the most severe form of chronic Cd intoxication. In order to prove that the anemia observed in chronic Cd intoxication arises from low production of EPO in the kidneys following the renal injury, we administered Cd to rats for a long period and performed the analysis of EPO mRNA inducibility in the kidneys. The rats administered Cd for 6 and 9 months showed anemia with low levels of plasma EPO as well as biochemical and histological renal tubular damage, and also hypoinduction of EPO mRNA in the kidneys. The results indicate that chronic Cd intoxication causes anemia by disturbing the EPO-production capacity of renal cells.

10Sa RNA is a bacterial small stable RNA, in which the 5'- and 3'-end sequences are folded into a tRNA-like structure. The RNA accepts alanine in vitro, and interacts with 70S ribosomes in the cells. In this study, we examined the ribosome-binding properties of Escherichia coli 10Sa RNA in vivo, and found that the aminoacylation ability of 10Sa RNA with alanine is necessary for the binding to 70S ribosomes. 10Sa RNA was also found to bind only to 70S monosomes and not to polysomes. Recently, E. coli 10Sa RNA was suggested to be used as mRNA for tag peptides, which were found to attach to the C-termini of truncated peptides synthesized in vivo. The present results are consistent with the 'trans-translation' model, which has been proposed for tag-peptide synthesis.

No abstract

No abstract