Polyadenylic acid on poliovirus RNA IV. Poly(U) in replicative intermediate and double-stranded RNA.
Explore the source record for details and available documents.
Base Sequence↗
Biomedical subjects
D H Spector
Publications and source records attributed to D H Spector.
Studies on the function of polyadenylic acid on poliovirus RNA.
RNAase H was used to remove selectively over 83% of 3' terminal polyadenylic acid [poly(A)] from poliovirus RNA. In a single cycle infection with this poly(A)-deficient RNA, no evidence for multiplication of the RNA was found. To elucidate further the function of poliovirus poly (A), the translational capacity of the RNAase H-treated and untreated RNA was studied in a cell-free protein synthesizing system prepared from HeLa cells. Removal of most of the poly(A) did not affect the pattern or amount of polypeptides synthesized. We conclude that the poly(A) on poliovirus RNA is probably necessary to the replication of the molecule.
Cell-Free System↗
Polyadenylic acid on poliovirus RNA. II. poly(A) on intracellular RNAs.
The content, size, and mechanism of synthesis of 3'-terminal poly(A) on the various intracellular species of poliovirus RNA have been examined. All viral RNA species bound to poly(U) filters and contained RNase-resistant stretches of poly(A) which could be analyzed by electrophoresis in polyacrylamide gels. At 3 h after infection, the poly(A) on virion RNA, relicative intermediate RNA, polyribosomal RNA, and total cytoplasmic 35S RNA was heterogeneous in size with an average length of 75 nucleotides. By 6 h after infection many of the intracellular RNA's had poly(A) of over 150 nucleotides in length, but the poly(A) in virion RNA did not increase in size suggesting that the amount of poly(A) which can be encapsidated is limited. At all times, the double-stranded poliovirus RNA molecules had poly(A) of 150 to 200 nucleotides. Investigation of the kinetics of poly(A) appearance in the replicative intermediate and in finished 35S molecules indicated that poly(A) is the last portion of the 35S RNA to be synthesized; no nascent poly(A) could be detected in the replicative intermediate. Although this result indicates that poliovirus RNA is synthesized 5' leads to 3' like other RNA's, it also suggests that much of the poly(A) found in the replicative intermediate is an artifact possibly arising from the binding of finished 35S RNA molecules to the replicative intermediate during extraction. The addition of poly(A) to 35S RNA molecules was not sensitive to guanidene.
Adenine Nucleotides↗
Polyadenylic acid on poliovirus RNA. III. In vitro addition of polyadenylic acid to poliovirus RNAs.
A crude RNA polymerase preparation was made from HeLa cells infected for 3 h with poliovirus. All virus-specific RNA species labeled in vitro (35S RNA, replicative intermediate RNA [RI], and double-stranded RNA [dsRNA]) would bind to poly(U) filters and contained RNase-resistant stretches of poly(A) which could be analyzed by electrophoresis in polyacrylamide gels. After incubation for 45 min with [3-H]ATP in the presence of the other three nucleoside triphosphates, the labeled poly(A) on the RI and dsRNA migrated on gels as relatively homogenous peaks approximately 200 nucleotides in length. In contrast, the poly(A) from the 35S RNA had a heterogeneous size distribution ranging from 50 to 250 nucleotides. In the absence of UTP, CTP, and GTP, the size of the newly labeled poly(A) on the dsRNA and RI RNA was the same as it was in the presence of all four nucleoside triphosphates. However the poly(A) on the 35S RNA lacked the larger sequences seen when the other three nucleoside triphosphates were present. When [3-H]ATP was used as the label in infected and uninfected extracts, heterogeneous single-stranded RNA sedimenting at less than 28S was also labeled. This heterogeneous RNA probably represents HeLa cytoplasmic RNA to which small lengths of poly(A) (approximately 15 nucleotides) had been added. These results indicate that in the in vitro system poly(A) can be added to both newly synthesized and preexisting RNA molecules. Furthermore, an enzyme capable of terminal addition of poly(A) exists in both infected and uninfected extracts.
Adenine Nucleotides↗
Poly(A) on mengovirus RNA.
The content and size of the poly(A) on Mengovirus RNA grown in both mouse L cells and HeLa cells have been examined. Virion RNA from either cell line could bind to poly(U) filters and contained RNase-resistant stretches of poly(A) which could be analyzed by electrophoresis in polyacrylamide gels. The size of the poly(A) on the Mengovirus RNA was independent of the host cell and averaged from 50 to 70 nucleotides.
HeLa Cells↗
The molecular biology of poliovirus.
Explore the source record for details and available documents.
Adenosine Monophosphate↗
Requirement of 3'-terminal poly(adenylic acid) for the infectivity of poliovirus RNA.
Ribonuclease H (EC 3.1.4.34) has been used to remove selectively much of the 3'-terminal poly(adenylic acid) [poly(A)] from poliovirus RNA by treating the RNA with the enzyme in the presence of poly(dT). Over 80% of the poly(A) could be removed and the residuum was found as oligo(A) stretches attached to many or all of the viral RNA molecules. Reduction of the size of the poly(A) markedly decreased the specific infectivity of poliovirus RNA, indicating that poly(A) is necessary to the infectivity of the RNA. The virions in plaques deriving from infection with treated RNA have a normal amount and size of poly(A), indicating that mechanisms exist in infected cells to regenerate normal length poly(A) from truncated poly(A).
Adenine Nucleotides↗
Molecular epidemiology of cytomegalovirus infections in premature twin infants and their mother.
Premature identical twins are described who according to molecular fingerprinting of their viral isolates, demonstrate a nonmaternal nursery source for their acquired cytomegalovirus (CMV) infections. The babies were born via cesarean section at 29 weeks gestation. Weekly urine screening of the infants indicated that at birth both were CMV-negative. Twin B developed CMV at 6 weeks of age, while Twin A developed his infection when he was 9 weeks old. Three months following delivery cervical and urine cultures of the infants' mother were negative and she had no detectable CMV antibody. At 6 months postpartum (2 months following both infants' discharge home) a repeat urine culture of their mother was positive for CMV, and here CMV-CF titer had risen to 1:128. DNA fingerprinting by restriction endonuclease digestion analyses of the viruses isolated from the two infants indicate that they were infected with different strains of CMV. In addition the DNA fingerprinting pattern of the mother's isolate is identical to that of Twin A. These cases give further evidence that hospitalized infants may acquire CMV from hospital sources and document by molecular fingerprinting for the first time to our knowledge that these babies may transmit the virus to CMV-seronegative individuals. This study also demonstrates how restriction endonuclease digestion analyses can be used as a powerful tool to study the epidemiology of CMV infections.
Adult↗