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S Osawa

Publications and source records attributed to S Osawa.

At least 145 records · Page 8Linked to original sources
PubMed1986

Evolutionary change in 5S rRNA secondary structure and a phylogenic tree of 352 5S rRNA species.

The secondary structure models of 5S rRNA have been constructed from the primary structure of 352 5S rRNA species available at present. All the 5S rRNAs examined can take essentially the same secondary structure, however they reveal characteristic differences between eukaryotes, metabacteria (= archaebacteria) and eubacteria. These three types of models can be further subgrouped by minor but characteristic differences. A phylogenic tree of organisms has been constructed using these 5S rRNA sequences by the weighted pairing method (WPG method). The tree reveals that there exist several major groups of eubacteria which seem to have diverged into different directions in the early stages of bacterial evolution. After emergence of eubacteria, metabacteria and eukaryotes separated from each other from their common ancestor. In the eukaryotic evolution, red algae (Rhodophyta) emerged first, and thereafter, thraustocytrids-Proctista, Ascomycota, green plants (green algae and land plants), Basidiomycota, Chromophyta (brown algae, diatoms and golden-yellow algae), slime- and water molds, various protozoans, and animals emerged in this order.

Animals↗
PubMed1986

Evolutionary relationship of denitrifying bacteria as deduced from 5S rRNA sequences.

The nucleotide sequences of 5S rRNA from seven denitrifying bacteria have been determined. Based on these sequences and those reported in the literature (including two denitrifiers), a phylogenic tree of 104 eubacterial 5S rRNA sequences has been constructed to establish the position of the denitrifying bacteria. These bacteria belong to either one of the three major subgroups of gram-negative bacteria. The grouping based on 5S rRNA sequences is almost compatible with the type of the nitrite reductases, with the one apparent exception of Paracoccus denitrificans ATCC 13543. Moreover, the separation time of most of the denitrifying bacteria from other non-denitrifying bacteria belonging to the same subgroup is recent. These results suggest that the denitrifying systems in these bacteria would have developed polyphyletically, and not so anciently, during eubacterial evolution.

Alcaligenes↗
PubMed1986

Phosphorylation of three proteins in the plasma membrane of Y-1 adrenal cells by a membrane-bound adenosine 3',5'-monophosphate-dependent protein kinase.

Highly purified plasma membranes from Y-1 adrenal tumor cells were incubated with [gamma-32P]ATP with and without cAMP to determine whether endogenous protein substrates are phosphorylated by a cAMP-dependent protein kinase. Three membrane proteins (mol wt 270,000, 35,000, and 17,000) were phosphorylated without cAMP and, to a greater extent, with the nucleotide (0.05-20 microM). Phosphorylation was rapid (less than 60 sec), specific for cAMP, and occurred exclusively at serine residues. Two of the three proteins (35,000 and 17,000) were phosphorylated in whole cells under the influence of cAMP when the cells were incubated with [32P]orthophosphate. The cAMP-dependent protein kinase of these plasma membranes was not extracted by Triton X-100 (0.5% wt/vol) nor by KCl (0.4 M) but was almost completely extracted by the two agents together. By means of photoactivation of 8-azido-[32P]cAMP, it was found that both regulatory subunits RI and RII are present in the membranes. To the extent that the second messenger acts only by way of protein kinase enzymes, these changes in the three proteins are likely to be important in the responses of the plasma membranes of adrenal cells to ACTH.

Adenosine Triphosphate↗
PubMed1986

Occurrence of spectrin-like protein in Y-1 adrenal tumor cells.

With the aid of two monospecific antibodies raised in rabbits (antimouse erythrocyte spectrin and antimouse brain spectrin), the presence of a spectrin-like protein was demonstrated in mouse adrenal tumor (Y-1) cells. Y-1 cells contain two large polypeptides, with mol wt characteristic of nonerythroid spectrin alpha- and beta-subunits (240,000 and 235,000). When proteins from plasma membranes of Y-1 cells were electrophoretically transferred to a nitrocellulose membrane, two polypeptides with mol wt of 240,000 and 225,000 were specifically stained with antimouse erythrocyte (rbc) spectrin immunoglobulin G (IgG). The rbc spectrin antibody was used to immunoprecipitate Y-1 spectrin from a neutral detergent (physiological ionic strength) cell extract. The 240,000 (alpha)- and 235,000 (beta)-dalton polypeptides were immunoprecipitated in a 1:1 molar ratio, despite the fact that the antibody recognizes only the alpha-subunit. Two-dimensional chymotryptic peptide-mapping analysis indicated that the 240,000- and 235,000-dalton subunits of Y-1 adrenal tumor spectrin are structurally unique and share limited homology with mouse rbc spectrin alpha- and beta-subunits, but are nearly identical to the mouse brain spectrin 240,000-dalton alpha-subunit and 235,000-dalton beta-subunit. Indirect immunofluorescence with anti-rbc or antibrain spectrin IgG and goat antirabbit IgG conjugated with rhodamine demonstrated intense staining at the plasma membrane and throughout the cytoplasm of Y-1 cells, with little staining within the nucleus.

Adrenal Gland Neoplasms↗
PubMed1985

Evolution of green plants as deduced from 5S rRNA sequences.

We have constructed a phylogenic tree for green plants by comparing 5S rRNA sequences. The tree suggests that the emergence of most of the uni- and multicellular green algae such as Chlamydomonas, Spirogyra, Ulva, and Chlorella occurred in the early stage of green plant evolution. The branching point of Nitella is a little earlier than that of land plants and much later than that of the above green algae, supporting the view that Nitella-like green algae may be the direct precursor to land plants. The Bryophyta and the Pteridophyta separated from each other after emergence of the Spermatophyta. The result is consistent with the view that the Bryophyta evolved from ferns by degeneration. In the Pteridophyta, Psilotum (whisk fern) separated first, and a little later Lycopodium (club moss) separated from the ancestor common to Equisetum (horsetail) and Dryopteris (fern). This order is in accordance with the classical view. During the Spermatophyta evolution, the gymnosperms (Cycas, Ginkgo, and Metasequoia have been studied here) and the angiosperms (flowering plants) separated, and this was followed by the separation of Metasequoia and Cycas (cycad)/Ginkgo (maidenhair tree) on one branch and various flowering plants on the other.

Journal Article↗
PubMed1985

UGA is read as tryptophan in Mycoplasma capricolum.

UGA is a nonsense or termination (opal) codon throughout prokaryotes and eukaryotes. However, mitochondria use not only UGG but also UGA as a tryptophan codon. Here, we show that UGA also codes for tryptophan in Mycoplasma capricolum, a wall-less bacterium having a genome only 20-25% the size of the Escherichia coli genome. This conclusion is based on the following evidence. First, the nucleotide sequence of the S3 and L16 ribosomal protein genes from M. capricolum includes UGA codons in the reading frames; they appear at positions corresponding to tryptophan in E. coli S3 and L16. Second, a tRNATrp gene and its product tRNA found in M. capricolum have the anticodon sequence 5' U-C-A 3', which can form a complementary base-pairing interaction with UGA.

Biological Evolution↗
PubMed1985

Identification of a spectrin-like protein in Sertoli cells.

Sertoli cells prepared from rats ages 15 and 25 days were shown to contain a spectrin-like protein. Indirect immunofluorescence with monospecific antimouse erythrocyte immunoglobulin G (IgG) and with monospecific antimouse brain spectrin IgG revealed specific staining in Sertoli cells. Both antibodies precipitated two spectrin-like peptides of 240,000 and 235,000 daltons from cells solubilized with octyl glucoside. Proteins from Sertoli cell membranes were separated by electrophoresis on polyacrylamide gels containing sodium dodecyl sulfate and electrophoretically transferred to nitrocellulose membrane. Incubation of nitrocellulose membrane with either of the two antibodies, followed by horseradish peroxidase conjugated to second antibody, revealed only the larger, or alpha, spectrin subunit (Western blots). Both antibodies were used to provide immunoautoradiographic identification of the spectrin-like protein. In this procedure, spectrin and Sertoli cell membranes were shown to compete with [125I]-labeled spectrin from mouse erythrocytes for binding to antimouse erythrocyte spectrin IgG. Finally, two-dimensional proteolytic mapping of the 240,000- and 235,000-dalton peptides demonstrated limited spot homology with rat erythrocyte spectrin. However, subcellular fractions from Sertoli cells all contained a spectrin-like protein showing high homology from fraction to fraction. It is concluded that Sertoli cells contain a spectrin-like protein that is seen in cell fractions prepared by centrifugation, i.e., mitochondria, microsomes, nuclei, cytoplasm, and plasma membranes. Although homology with spectrin from erythrocytes or brain is not seen in peptide maps, the alpha subunit shares antigenic determinants with spectrin from erythrocytes. The beta subunit is believed to be precipitated by antispectrin as the result of binding to the alpha subunit, since the beta subunit shows no detectable antigenic homology with that of spectrin.

Animals↗
PubMed1985

Adenosine 3',5'-monophosphate-dependent protein kinase associated with the cytoskeleton of adrenal tumor cells.

Preparations of cytoskeleton from Y-1 cells were found to phosphorylate various cytoskeletal proteins when incubated with [gamma-32P]ATP. When cAMP was added to the cytoskeleton, a rapid increase in phosphorylation of cytoskeletal protein was observed, and changes were seen in the phosphorylation of individual proteins; four additional proteins were phosphorylated (mol wt, 165,000, 92,000, 45,000, and 24,000) and three proteins were more intensely phosphorylated than without cAMP (mol wt, 125,000, 51,000, and 38,000). In addition, one protein (mol wt, 96,000) that was intensely phosphorylated without cAMP was not phosphorylated with the cyclic nucleotide, and a second (mol wt, 48,000) was less phosphorylated. The increased level of total phosphorylation returned to the unstimulated level within 10 min. The increased phosphorylation of proteins produced by cAMP was inhibited by protein kinase inhibitor. cAMP-dependent protein kinase activity was closely associated with the cytoskeleton, since it was not removed by Triton X-100 (1%, wt/vol), although some activity could be extracted with buffer containing high concentrations of salt. When the cytoskeleton of Y-1 cells was subjected to treatments that disrupt the cytoskeleton before the cells were extracted (cytochalasin B, colchicine, and sonication), no change was seen in cAMP-dependent protein kinase activity. However, cytochalasin B increased phosphorylation of two proteins that were not phosphorylated by cAMP-dependent kinase (mol wt, 63,000 and 43,000). Sonication of the cytoskeleton before addition of [gamma-32P]ATP caused a number of changes in cAMP-independent phosphorylation, but did not affect cAMP-dependent phosphorylation. cAMP-dependent phosphorylation required Mg2+ and was inhibited by Ca2+. It is concluded that the cytoskeleton of Y-1 cells contains bound cAMP-dependent protein kinase that phosphorylates certain cytoskeleton proteins. The cytoskeleton also contains one or more cAMP-independent kinase systems. It is suggested that the cAMP-dependent protein kinase described here may be important in the cytoskeletal responses to ACTH.

Adenosine Triphosphate↗
PubMed1985

Plasma membranes from adrenal cells: purification and properties.

A method is reported for preparing surface (plasma) membranes from adrenal tumour (Y-1) cells. The procedure is based upon homogenization in hypotonic ZnCl2 followed by sedimentation through two sucrose density gradients. The purified membranes consist of large sheets of membrane. The identity and purity of the membranes was demonstrated by: (1) microscopy (phase contrast and electron); (2) enzyme markers; and (3) functional activities associated with plasma membranes (binding of ACTH and LDL and adenylate cyclase). Phase-contrast microscopy revealed the release of membrane ghosts free from cytoplasm and nuclei. Electron microscopy showed membranes with small fragments of cytoplasm attached to the inside. Binding of ACTH was found to be specific with KD 0.12 nM and the equivalent of 2500 sites per cell. Binding of LDL was also specific with KD 0.5 nM and the equivalent of 4800 sites per cell. Specific activities of binding for ACTH and LDL were increased by 21-fold and 15-fold, respectively, relative to whole homogenate. Membranes were also prepared from beef fasciculata cells by the same method.

Adrenal Gland Neoplasms↗
PubMed1984

Preferential use of A- and U-rich codons for Mycoplasma capricolum ribosomal proteins S8 and L6.

The nucleotide sequence of the 1.3 kilobase-pair DNA segment, which contains the genes for ribosomal proteins S8 and L6, and a part of L18 of Mycoplasma capricolum, has been determined and compared with the corresponding sequence in Escherichia coli (Cerretti et al., Nucl. Acids Res. 11, 2599, 1983). Identities of the predicted amino acid sequences of S8 and L6 between the two organisms are 54% and 42%, respectively. The A + T content of the M. capricolum genes is 71%, which is much higher than that of E. coli (49%). Comparisons of codon usage between the two organisms have revealed that M. capricolum preferentially uses A- and U-rich codons. More than 90% of the codon third positions and 57% of the first positions in M. capricolum is either A or U, whereas E. coli uses A or U for the third and the first positions at a frequency of 51% and 36%, respectively. The biased choice of the A- and U-rich codons in this organism has been also observed in the codon replacements for conservative amino acid substitutions between M. capricolum and E. coli. These facts suggest that the codon usage of M. capricolum is strongly influenced by the high A + T content of the genome.

Adenine↗
PubMed1984

Evolution of multicellular animals as deduced from 5S rRNA sequences: a possible early emergence of the Mesozoa.

The nucleotide sequences of 5S rRNA from a mesozoan Dicyema misakiense and three metazoan species, i.e., an acorn-worm Saccoglossus kowalevskii, a moss-animal Bugula neritina, and an octopus Octopus vulgaris have been determined. A phylogenic tree of multicellular animals has been constructed from 73 5S rRNA sequences available at present including those from the above four sequences. The tree suggests that the mesozoan is the most ancient multicellular animal identified so far, its emergence time being almost the same as that of flagellated or ciliated protozoans. The branching points of planarians and nematodes are a little later than that of the mesozoan but are clearly earlier than other metazoan groups including sponges and jellyfishes. Many metazoan groups seem to have diverged within a relatively short period.

Animals↗
PubMed1984

Organization of ribosomal RNA genes in Mycoplasma capricolum.

DNA segments carrying rRNA genes of Mycoplasma capricolum have been cloned and characterized by restriction endonuclease mapping, DNA-RNA hybridization and nucleotide sequencing. The M. capricolum genome has two sets of rRNA gene clusters, where the arrangement is in the order of (5')16S-23S-5S(3'). The spacer region between 16S and 23S rDNA is extremely rich in AT and does not carry any tRNA genes.

Base Sequence↗
PubMed1984

Nucleotide sequence of the rrnB 16S ribosomal RNA gene from Mycoplasma capricolum.

The nucleotide sequences of the rrnB 16S ribosomal RNA gene and its 5'-and 3'-flanking regions from Mycoplasma capricolum have been determined. The coding sequence is 1521 base pairs long, being 21 base pairs shorter than that of the Escherichia coli 16S rRNA gene. The 16S rRNA sequence of M. capricolum reveals 74% and 76% identify with that of E. coli and Anacystis nidulans, respectively. The secondary structure model constructed from the M. capricolum 16S rRNA gene sequence resembles that proposed for E. coli 16S rRNA. A large stem structure can be constructed between the 5'- and 3'-flanking sequences of the 16S rRNA gene. The flanking regions are extremely rich in AT.

Base Sequence↗
PubMed1984

Molecular cloning of ribosomal protein genes from Mycoplasma capricolum.

A Bg/II-fragment from the Mycoplasma capricolum DNA cloned into pBR322 has been found to contain a cluster of ribosomal protein genes. The recombinant plasmid, pMCB1088, includes a 9 kilobase-pair insert that codes for at least eight ribosomal proteins of M. capricolum. The protein genes are expressed in Escherichia coli cells.

Chromosome Deletion↗
PubMed1984

Role of actin in the responses of adrenal cells to ACTH and cyclic AMP: inhibition by DNase I.

Erythrocyte ghosts were loaded with pancreatic DNase I and fused with Y-1 adrenal tumor cells to test the possibility that this enzyme might inhibit the steroidogenic responses of the cells to ACTH and cyclic AMP. Fusion of erythrocyte ghosts loaded with DNase I, but not those containing albumin, ovalbumin, boiled DNase I, or DNase I with excess G-actin, inhibited the increase in production of 20 alpha-dihydroprogesterone produced by ACTH and dibutyryl cyclic AMP; inhibition was concentration-dependent with 50% inhibition by 3 X 10(7) molecules of DNase I per cell. It was found that inhibition by DNase I was exerted at the step in the steroidogenic pathway at which cholesterol is transported to mitochondria where steroidogenesis begins. This was shown by measuring transport of cholesterol into the inner mitochondrial membrane, by measuring the production of pregnenolone by isolated mitochondria and by demonstrating that DNase I was without effect on the conversion of pregnenolone to 20 alpha-dihydroprogesterone (an end-product of steroid synthesis). The actin content of Y-1 cells was measured by two methods based upon inhibition of DNase I and by SDS gels following centrifugation. The cells were found to contain 2-3 X 10(7) molecules of actin per cell of which two-thirds is present as G-actin. Since DNase I is known to bind to G-actin to give a one to one complex, these and other findings suggest that at least some of the G-actin in the cells may be necessary for the steroidogenic responses to ACTH and cyclic AMP.

Actins↗
PubMed1984

Secondary structure and phylogeny of Staphylococcus and Micrococcus 5S rRNAs.

Nucleotide sequences of 5S rRNAs from four bacteria, Staphylococcus aureus Smith (diffuse), Staphylococcus epidermidis ATCC 14990, Micrococcus luteus ATCC 9341 and Micrococcus luteus ATCC 4698, were determined. The secondary structural models of S. aureus and S. epidermidis sequences showed characteristics of the gram-positive bacterial 5S rRNA (116-N type [H. Hori and S. Osawa, Proc. Natl. Acad. Sci. U.S.A. 76:381-385, 1979]). Those of M. luteus ATCC 9341 and M. luteus ATCC 4698 together with that of Streptomyces griseus (A. Simoncsits, Nucleic Acids Res. 8:4111-4124, 1980) showed intermediary characteristics between the gram-positive and gram-negative (120-N type [H. Hori and S. Osawa, 1979]) 5S rRNAs. This and previous studies revealed that there exist at least three major groups of eubacteria having distinct 5S rRNA and belonging to different stems in the 5S rRNA phylogenic tree.

Base Sequence↗