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K Ohyama

Publications and source records attributed to K Ohyama.

At least 181 records · Page 10Linked to original sources
PubMed1988

Structure and organization of Marchantia polymorpha chloroplast genome. II. Gene organization of the large single copy region from rps'12 to atpB.

The nucleotide sequence (56,410 base-pairs) of the large single-copy region of chloroplast DNA from the liverwort Marchantia polymorpha has been determined. The sequence starts from one end (JLA) of the large single-copy region and encompasses genes for 21 tRNAs, six ATPase subunits (atpA, atpB, atpE, atpF, atpH and atpI), two photosystem I polypeptides (psaA and psaB), four photosystem II polypeptides (psbA, psbC, psbD and psbG), five ribosomal proteins (rps2, rps4, rps7, rps'12 and rps14), and three RNA polymerase subunits (rpoB, rpoC1 and rpoC2). In addition, we detected 18 open reading frames ranging from 29 to 2136 amino acid residues long, four of which share significant amino acid sequence homology to those of an Escherichia coli malK protein (designated mbpX), human mitochondrial ND2 (ndh2) and ND3 (ndh3) of a respiratory chain NADH dehydrogenase, or a bacterial antenna protein of a light-harvesting complex (lhcA). Sequence analysis suggests that four tRNA genes and six protein genes might be split by introns; they are trnG(UCC), trnK(UUU), trnL(UAA), trnV(UAC), atpF, ndh2, rpoC1, rps'12, ORF135 and ORF167. In the large single-copy region described here, the gene organization deduced is highly conserved with respect to that of higher plants, but an inversion of some 30,000 base-pairs flanked by trnL(CAA) and trnD(GUC) was seen between the liverwort and tobacco chloroplast genomes.

Adenosine Triphosphatases↗
PubMed1988

Structure and organization of Marchantia polymorpha chloroplast genome. III. Gene organization of the large single copy region from rbcL to trnI(CAU).

The nucleotide sequence (25,320 base-pairs) of a part of the large single-copy region of chloroplast DNA from the liverwort Marchantia polymorpha was determined. This region encodes putative genes for four tRNAs, isoleucine tRNA(CAU), arginine tRNA(CCG), proline tRNA(UGG) and tryptophan tRNA(CCA); eight photosynthetic polypeptides, the large subunit of ribulose bisphosphate carboxylase/oxygenase (rbcL), 51,000 Mr photosystem II chlorophyll alpha apoprotein (psbB), apocytochrome b-559 polypeptides (psbE and psbF), 10,000 Mr phosphoprotein (psbH), cytochrome f preprotein (petA), cytochrome b6 polypeptide (petB), and cytochrome b6/f complex subunit 4 polypeptide (petD); 13 ribosomal proteins (L2, L14, L16, L20, L22, L23, L33, S3, S8, S11, S12, S18 and S19); initiation factor 1 (infA); ribosome-associating polypeptide (secX); and alpha subunit of RNA polymerase (rpoA). Functionally related genes were located in several clusters in this region of the genome. There were two ribosomal protein gene clusters: rpl23-rpl2-rps19-rpl22-rps3-rpl16-+ ++rpl14-rps8-infA-secX-rps11-rpoA, with a gene arrangement similar to that of the Escherichia coli S10-spc-alpha operons, and the rps12'-rpl20-rps18-rpl33 cluster. There were gene clusters encoding photosynthesis components such as the psbB-psbH-petB-petD and the psbE-psbF clusters. Thirteen open reading frames, ranging in length from 31 to 434 amino acid residues, remain to be identified.

Amino Acid Sequence↗
PubMed1988

Structure and organization of Marchantia polymorpha chloroplast genome. IV. Inverted repeat and small single copy regions.

We characterized the genes in the regions of large inverted repeats (IRA and IRB, 10,058 base-pairs each) and a small single copy (SSC 19,813 bp) of chloroplast DNA from Marchantia polymorpha. The inverted repeat (IR) regions contain genes for four ribosomal RNAs (16 S, 23 S, 4.5 S and 5 S rRNAs) and five transfer RNAs (valine tRNA(GAC), isoleucine tRNA(GAU), alanine tRNA(UGC), arginine tRNA(ACG) and asparagine tRNA(GUU)). The gene organization of the IR regions in the liverwort chloroplast genome is conserved, although the IR regions are smaller (10,058 base-pairs) than any reported in higher plant chloroplasts. The small single-copy region (19,813 base-pairs) encoded genes for 17 open reading frames, a leucine tRNA(UAG) and a proline tRNA(GGG)-like sequence. We identified 12 open reading frames by homology of their coding sequences to a 4Fe-4S-type ferredoxin protein, a bacterial nitrogenase reductase component (Fe-protein), five human mitochondrial components of NADH dehydrogenase (ND1, ND4, ND4L, ND5 and ND6), two Escherichia coli ribosomal proteins (S15 and L21), two putative proteins encoded in the kinetoplast maxicircle DNA of Leishmania tarentolae (LtORF 3 and LtORF 4), and a bacterial permease inner membrane component (encoded by malF in E. coli or hisQ in Salmonella typhimurium).

Amino Acid Sequence↗
PubMed1988

Volume flow rate of perilymph in the guinea-pig cochlea.

The rate of longitudinal flow of perilymph has been measured using an ionic tracer technique. Spread of the tracer trimethylphenylammonium (TMPA) along the perilymphatic scalae was monitored with ion-selective microelectrodes following injection of a minute bolus (approximately 50 nl) of 150 mM TMPAC1 one turn away. This amount of TMPA had virtually no toxic effect on cochlear function. The spread of tracer by longitudinal volume flow and passive diffusion were separated by comparing tracer movements in both apical and basal directions along the scalae in two groups of animals. Experimental findings were compared with a mathematical model which combined diffusion and volume flow. Our results demonstrated that when electrodes were completely sealed into the cochlea, the rate of longitudinal volume flow in scala tympani was extremely slow, approximately 1.6 nl/min in the apical direction. Longitudinal flow was not detectable in scala vestibuli. When the otic capsule was perforated, flow rates of over 1 microliter/min were recorded in scala tympani, probably as a result of cerebrospinal fluid entry through the cochlear aqueduct. When the cochlea was sealed (with recording electrodes in place) and cerebrospinal fluid pressure was released, there was no significant basally-directed flow of perilymph in scala tympani. These findings support the concept that perilymph composition is maintained by local, cochlear mechanisms which do not involve longitudinal volume flow. They provide strong evidence that perilymph is not secreted in one region and resorbed at a spatially distant site.

Action Potentials↗
PubMed1988

Divergent mRNA transcription in the chloroplast psbB operon.

The genes psbB, psbH, petB and petD for the components in photosystem II and the cytochrome b6/f complex are clustered and co-transcribed in liverwort Marchantia polymorpha chloroplasts. On the opposite DNA strand in the spacer region between the genes psbB and psbH, we deduced an open reading frame consisting of 43 sense codons, and designated it as the ORF43 gene. The ORF43 gene was actively transcribed in liverwort chloroplasts. The ORF43 transcripts were entirely complementary to a part of the primary transcripts of the psbB operon. Heterogeneous Northern hybridization showed that the mRNA transcripts for the ORF43 gene increased with greening in pea seedlings. This is the first demonstration of divergent overlapping transcription in chloroplasts.

Amino Acid Sequence↗
PubMed1988

Ordered processing and splicing in a polycistronic transcript in liverwort chloroplasts.

From the complete sequence of the chloroplast DNA in a liverwort, Marchantia polymorpha, an unidentified open reading frame, ORF203, was found between the psbB and rps12' (trans-split) genes. ORF203 was a split gene consisting of three exons and two group II introns. Multiple transcripts for ORF203 were detected on Northern blots of the chloroplast RNA preparation. The ORF203 locus was primarily co-transcribed with the downstream genes rps12' and rpl20, and then processed into a monomeric precursor. S1 nuclease mapping gave the transcription initiation site 52 nucleotides upstream from the coding sequence of ORF203. The spliced RNA molecules were identified, as predicted, by the use of synthetic oligodeoxyribonucleotide probes specific to ligated exon sequences. The splicing reaction proceeded successively from the 5' to 3' direction. These results indicate that ordered RNA processing occurs in the chloroplast of land plants. Trans-membrane analysis by a computer indicated that ORF203 gene product could be associated with a chloroplast membrane.

Amino Acid Sequence↗
PubMed1988

Release of atrial natriuretic peptide from the isolated, blood-perfused right atrium of the dog.

Release of atrial natriuretic peptide (ANP) was investigated using the isolated right atrium (RA) cross-circulated with heparinized arterial blood of the donor dog. ANP concentration of the blood was measured by radioimmunoassay. The plasma ANP concentration of the arterial blood of the donor dog (ANP-D) which perfused the RA preparation was 111 +/- 18 pg/ml (n = 4), while the ANP concentration of venous blood leaving the RA preparation (ANP-A) was 1680 +/- 220 pg/ml (n = 4). In comparison, the plasma ANP concentration of venous blood leaving the isolated papillary muscle of the right ventricle (ANP-V) was 106 +/- 19 pg/ml (n = 4), which was not significantly different from the ANP-D concentration. When the right atrium was electrically driven at a rate of 100 beats/min, almost the same rate as the spontaneous sinoatrial rate of 98 +/- 6 beats/min (n = 4), the ANP-A concentration was not changed (1630 +/- 160 pg/ml, n = 4). When the driving rate was increased to 200 beats/min, the ANP-A concentration was significantly increased to 2250 +/- 130 pg/ml (n = 4). These results suggest that ANP is exclusively secreted from the atrium, but not from the ventricle, and that release of ANP is directly related to atrial rate.

Animals↗
PubMed1988

[Three-dimensional analysis of maxillary alveolar process in bilateral cleft lip and palate patients].

The collapsed maxillary alveolar arch in bilateral cleft lip and palate (BCLP) patients was quantitatively evaluated by three dimensional analysis. Materials were consisted of alveolar models taken from 15 Japanese boys (11 years old) with BCLP. The findings obtained were as follows: 1. Examination of the alveolar displacement in individual BCLP patients disclosed a marked tendency of inward and upward displacement of the lateral segments. On the other hand, premaxilla showed an upward displacement in the vertical dimension with a great deal of variation in the amount and direction of horizontal displacement. 2. Concerning the average amount of horizontal displacement, the premaxilla showed relatively little, but the lateral segment, especially the left one, showed a considerably large amount. In the vertical dimension, both the premaxilla and lateral segment were displaced markedly upward. 3. Patterns of collapsed alveolar arch in BCLP patients were classified according to the amount of horizontal displacement of the premaxilla into the following 4 types; type A (larger displacement towards the inside), type B (moderate or smaller displacement towards the inside), type C (moderate or smaller displacement towards the outside) and type D (larger displacement towards the outside). The order of prevalence of these 4 types was B,C,A,D in order. On the other hand, in the vertical dimension, the direction of displacement of the premaxilla was upward in all patients. 4. The anterior edge of the lateral segments showed the largest amount of displacement both in the horizontal and vertical dimensions. In a comparison of these results with those of Unilateral Cleft Lip and Palate (UCLP), the total amount of horizontal displacement of the maxillary alveolar process was larger in UCLP, while the vertical one was larger in BCLP. A remarkable difference between BCLP and UCLP was found in the displacement of the anterior region due to the premaxilla in BCLP.

Alveolar Process↗
PubMed1988

Glycolipids of rat glomerular mesangial cells: antibody against the cells reacts specifically to isoglobotetraosylceramide.

Cultured rat glomerular mesangial cells had relatively simple glycolipid composition which comprised mainly monoglycosylceramide, diglycosylceramide, isoglobotetraosylceramide and GM3. Beside these glycolipids, sulfatide, polar gangliosides and an unknown neutral glycolipid were detected in whole kidney and tubules. Polyclonal antibody against the cultured rat mesangial cells, which induced glomerular injury in vivo, bound specifically with isoglobotetraosylceramide.

Animals↗
PubMed1987

Time-related changes in cochlear potentials in guinea pigs with experimentally induced endolymphatic hydrops.

In order to examine the changes in cochlear function occurring in hydropic ears over time, endolymphatic hydrops was provoked by obliterating the endolymphatic sac in 62 albino guinea pigs. Cochlear potentials (EP, CM, SP and AP) were recorded in the 1st, 2nd, 4th and 12th postoperative weeks, respectively. A significant reduction in the level of EP was already observed in the 2nd week and the potential was further suppressed by the 4th week. There was no significant difference between the levels of the 4th and 12th weeks. The amplitudes of CM and AP decreased progressively as time elapsed after the surgery. In sharp contrast to the other potentials, the abnormality in SP was most frequently observed in the 1st week. These results are discussed in the light of the available literature.

Action Potentials↗
PubMed1987

Cochlear potentials of guinea pigs with experimentally induced renal failure.

In order to investigate the relationship between renal failure and hearing loss, the authors made a guinea pig model with experimentally induced renal failure and examined cochlear potentials (N1, CM and EP). When renal damage was greater, the amplitudes of N1 and CM were decreased and the latency of N1 was prolonged, but EP was within normal range. The sensory cells of the cochlea were considered responsible for the hearing loss in the guinea pig model. No pathological alterations of the cochlea were revealed by a light microscopy. It is suggested that the etiology of the hearing loss was due mainly to metabolic disturbances such as uremic toxins, electrolyte imbalance or endocrine abnormalities.

Acute Kidney Injury↗
PubMed1987

Sound perception in the ultrasonic region.

The mechanism of ultrasonic perception was investigated electrocochleographically in guinea pigs (1) to compare AP responses in normal animals with those in kanamycin-poisoned animals with a damaged outer hair cell system; (2) and to analyse the masking property of continuous ultrasonic sound upon the AP evoked by burst stimuli within the auditory field. The study revealed several facts indicating the breakdown of cochlear sharp frequency analysis in the transduction of ultrasonic sound. We concluded that the sound perception in the ultrasonic region could be performed by the inner hair cell system without any enhancement or modulation of the outer hair cell system, which was regarded as an important process in a recent model of cochlear micromechanics.

Action Potentials↗