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Biomedical subjects

F Harada

Publications and source records attributed to F Harada.

At least 55 records · Page 3Linked to original sources
PubMed1983

Chemical modification of guanine residues of mouse 5 S ribosomal RNA with kethoxal. (Nucleosides and nucleotides 46).

Chemical modification of mouse 5 S rRNA with kethoxal was carried out to examine the secondary structure. The guanine residues located at positions 37, 41, 56, 66, 75 and 89 were modified. The relative rates of reaction are in the order G37, G56, G89, G66, G41, G75 at 28 degrees C and G37, G41, G56, G89, G75, G66 at 35 degrees C. These results support a secondary structure model containing 5 helices and 5 loops and indicate that the region around position 37 is the most exposed in higher-order structure.

Aldehydes↗
PubMed1983

Chemical modification of cytosine residues of mouse 5 S ribosomal RNA with hydrogen sulfide. (Nucleosides and nucleotides 43).

Cytosine residues of nucleic acids were converted to 4-thiouracil residues with hydrogen sulfide in pyridine and water to examine the secondary and tertiary structures of mouse 5 S rRNA. The cytosine residues at positions 10, 24, 34 (or 36), 39, 44 (or 46) and 63 were converted preferentially when the treatment was carried out at 28 degrees C. This result supports the model of the secondary structure of 5 S rRNA of Nishikawa, K. and Takemura, S. ((1974) FEBS Lett. 40, 106-109) consisting of five helices and five loops. As the temperature was increased to 35 degrees C, additional cytosine residues in positions 26, 52 and 78 were modified to moderate extents.

Animals↗
PubMed1983

Minor serine tRNA containing anticodon NCA (C4 RNA) from human and mouse cells.

The nucleotide sequence of C4 RNA, one of the "4.5S RNAs" of HeLa cells, was determined. This RNA consists of 90 nucleotides containing C-C-A at its 3'-terminus. The sequence can be drawn to form a clover-leaf structure with several unusual features and with anticodon NCA. The short term labeled molecule contains triphosphates at its 5'-terminus, whereas the mature molecule contains only monophosphate. Therefore, there must be no precursor nucleotide at the 5'-end in the primary transcript of this tRNA. Mouse cells also contain C4 RNA. Only one base exchange was observed in the extra arm in human and mouse C4 RNAs. The molecule purified from mouse liver showed serine acceptor ability.

Animals↗
PubMed1983

Chemical modification of adenine residues in mouse 5S rRNA with monoperphthalate: the secondary structure of 5S rRNA.

The chemical modification of adenine residues in mouse 5S rRNA with monoperphthalate was carried out to investigate the higher ordered structure of 5S rRNA. The adenine residues at positions 11, 22 (or/and 23), 49 (or/and 50), 54 (or/and 55), 77, 83, 88, 90 and 100 (or/and 101) were modified. This result further confirmed the secondary structure of 5S rRNA constituted of 5 helices and 5 loops postulated by other chemical modifications.

Animals↗
PubMed1982

Correlation between effects of 24 different cytochalasins on cellular structures and cellular events and those on actin in vitro.

To compare the effects of cytochalasins on the cellular level with those on the molecular level, 24 cytochalasins, 20 natural compounds and 4 derivatives, were used. The following effects were tested for each of 24 cytochalasins; (a) four high dose (2-20 muM) effects on the cellular level: rounding up of fibroblastic cells, contraction of actin cables, formation of hairy filaments containing actin, and inhibition of lymphocyte capping; (b) a low dose (0.2-2 muM) effect: inhibition of membrane ruffling; and (c) two in vitro effects: an inhibition of actin filament elongation (the high affinity effect [low dose effect] in vitro) and an effect on viscosity of actin filaments(the low affinity effect [high dose effect] in vitro). These results indicated that there are almost the same hierarchic orders of relative effectiveness of different cytochalasins between low and high dose effects and between cellular and molecular effects. From the data obtained with the 24 cytochalasins, we have calculated correlation coefficients of 0.87 and 0.79 between an effect in vivo, inhibition of capping, and an effect in vitro, inhibition of actin filament elongation, as well as between inhibition of capping and another effect in vitro, effect on viscosity of actin filaments, respectively. Furthermore, a correlation coefficient between the high affinity effect and the low affinity effect determined in vitro was calculated to be 0.90 from the data obtained in this study. The strong positive correlation among low and high dose effects in vivo and those in vitro suggests that most of the effects caused by a cytochalasin, irrespective of doses or affected phenomena, might be attributed to the interaction between the drug and the common target protein, actin. In the course of the immunofluorescence microscope study on cytochalasin-treated cells using actin antibody, we have found that aspochalasin D, a 10-isopropylcytochalasin, strongly induced the formation of rodlets containing actin in the cytoplasm of the treated fibroblasts. In contrast, the other cytochalasins, including cytochalasin B, cytochalasin C, cytochalasin D, and cytochalasin H, were found to induce the formation of nuclear rodlets. Both cytoplasmic and nuclear rodlets found in the cytochalasin-treated cells were similar in ultrastructures to those induced by 5 to 10 percent (vol/vol) dimethyl sulfoxide in the same type of cells.

Actins↗
PubMed1981

Biological and structural differences between tRNAVal species isolated from rat ascites hepatoma cells and normal rat liver.

On RPC-5 column chromatography, the main valine acceptor activity of tRNA (tRNA2Val) from rat ascites hepatoma cells was eluted later than that of normal rat liver tRNA (tRNA1Val). The tRNA2Val was aminoacylated by E. coli amino-acyl-tRNA synthetase, while tRNA1Val from normal rat liver was not. Rat fetal liver tRNAVal was also aminoacylated by E. coli aminoacyl-tRNA synthetase. tRNA1Val (rat liver) and tRNA2Val (ascites hepatoma) were each purified to a homogeneous state by RPC-5 column chromatography and two-dimensional polyacrylamide gel electrophoresis, and their sequences were determined by post-labeling techniques. Ascites hepatoma tRNA2Val differed from rat liver tRNA1Val in that Gm18, C32 and an unknown modified nucleoside, N34, in the latter tRNA were mostly replaced by G, Cm, and inosine, respectively. In addition, 3'-terminal adenosine was not present in tRNA1Val (normal rat liver), but was in tRNA2Val (ascites hepatoma). Other modifications and the primary structures of the two tRNAValS were found to be the same. Thus it was concluded that the new iso-acceptor species of tRNA Val in ascites hepatoma cells is due to a change of post-transcriptional modification, not to a change of tRNA transcription. The unique feature of the change of post-transcriptional modification in tRNA2Val (ascites hepatoma) is that both hypo- and hyper-modification take place simultaneously in the tRNA molecule depending the locations of nucleotide residues.

Amino Acids↗
PubMed1981

Mode of degradation of tRNAs with ozone.

Ozone-treatment of tRNA resulted in the degradation of guanine residues located on the loop regions, such as the anticodon and D-loop region. In addition, it became evident that the guanine residues in the consecutive sequences, such as G-G-G-G and G-G-m1G in tRNAPro, were the most susceptive to the ozone-treatment. The internucleotidic linkage of the treated tRNA was not cleaved but several fragments were obtained by a gel electrophoretic separation after heating at 60% in 1M aniline-acetate buffer (pH 4.5). Major fragments derived from tRNAPro were the 3'-half and the 5'-half molecules produced by the cleavage at the anticodon region.

Anticodon↗
PubMed1980

Primary structure of AUA-specific isoleucine transfer ribonucleic acid from Escherichia coli.

The nucleotide sequence of an E. coli isoleucine tRNA (tRNAIle minor) specific for the codon AUA was determined by postlabeling procedures using only 2.5 micrograms (0.05 A260 unit) of the material. The sequence was pG-G-C-C-C-C-U-s4U-A-G-C-U-C-A-G-U-Gm-G-D-D-A-G-A-G-C-A-A-G-C-G-A-C-U-N+-A-U-t6A-A-psi-C-G-C-U-U-G-m7G-acp3U-C-G-C-U-G-G-T-psi-C-A-A-G-U-C-C-A-G-C-A-G-G-G-G-C-C-A-C-C-AOH. The nucleotide sequences in the regions of the D arm and T psi C arm of tRNAIle minor were quite similar to the corresponding regions of tRNAIle major. However, the sequences in the CCA stem and anticodon stem of tRNAIle minor were different from those of tRNAIle major. The overall homology between the two isoleucine tRNAs was 68%. E. coli tRNALys, tRNAMet, tRNAValIIA and tRNAArg also have relatively high sequence homology with tRNAIle minor.

Base Sequence↗
PubMed1980

Nucleotide sequences of 4.5S RNAs associated with poly(A)-containing RNAs of mouse and hamster cells.

The nucleotide sequences of 4.5S RNAs associated with poly-(A)-containing RNAs of mouse and hamster cells were determined. These RNAs have 91 to 94 nucleotides, a high content of G (almost 40%) and no modified nucleoside. The 5'-termini are pppG, but the 3'-termini lack uniformity in the number of uridylate residues. These molecules contain two sets of repeating sequences, and a central purine-rich sequence. There is only one base exchange between mouse and hamster 4.5S RNAs. Possible binding sites of these RNAs to poly(A)-containing RNAs are discussed.

Animals↗
PubMed1980

Primary structure of Escherichia coli tRNA UUR Leu. Presence of an unknown adenosine derivative in the first position of the anticodon which recognizes the UU codon series.

The primary structure of Escherichia coli tRNA UUR Le which recognizes the UU series of codons has been determined. The sequence is pG-C-C-C-G-G-A-s4U-G-G-U-G-G-A-A-D-C-Gm-C-D-A-G-A-C-A-C-A-A-G-G-G-A-psi-U-N-A-A-ms2i6A-A-psi-C-C-C-C-U-C-G-G-C-G-G-C-G-U-U-C-G-C-G-C-U-G-U-G-C-G-G-G-T-psi-C-A-A-G-U-C-C-C-G-C-U-C-C--G-G-G-U-A-C-C-A. The chain length of tRNA UUR Leu is 87 residues, the same as other E. coli tRNA Leu s and T4 phage-coded tRNA Leus. Its sequence is especially similar to that of E. coli tRNA2 Leu in the Darm and T psi C arm regions. E. coli tRNA UUR Leu contains an unknown modified nucleoside in the first position of the anticodon and was shown by mass spectrometry and chemical degradation to be an adenosine derivativee. Addition of tRNA UUR Leu to a cell-free protein-synthesizing system with high Mg2+ concentration resulted in the formation of polyleucine miscoded by poly(U), indicating that the unknown modified nucleoside exhibits a tendency to recognize U under certain conditions.

Anticodon↗