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Biomedical subjects

K Itakura

Publications and source records attributed to K Itakura.

At least 181 records · Page 10Linked to original sources
PubMed1976

Chemical and enzymatic synthesis of lactose operator of Escherichia coli and its binding to lactose repressor.

The 21-nucleotide-long duplex DNA constituting the lactose operator sequence of E. coli has been synthesized by both chemical and enzymatic methods. The synthetic duplex has the essential feature of the lactose operator as seen by its binding to the lactose repressor. The binding of the synthetic operator fragment to the lactose repressor is specific because it is inhibited by the inducing ligand isopropyl-beta-D-thiogalactoside. Thus, it is now possible to show that a chemically synthesized oligodeoxynucleotide can be specifically recognized by its natural regulatory protein.

Bacterial Proteins↗
PubMed1976

Heredity of the GIX thymocyte antigen associated with murine leukemia virus: segregation data simulating genetic linkage.

The GIX antigen is a feature of the gp70 envelope glycoprotein of murine luekemia virus (MuLV). This GIX-gp70 molecule is found on the thymocytes of some (GIX+) strains of mice, where its expression is controlled by two mendelian genes, Gv-1 and Gv-2. Previous recombination data involving the prototype GIX+ strain 129 indicated that the H-2 (chromosome 17) and Gv-1 loci are linked, at a distance of 36 units from one another. New data indicate that the association of H-2 and GIX phenotypes is an example of quasi-linkage, evidently dependent in this instance on heterozygosity at a locus or loci in the vicinity of H-2. Other previous recombination data, involving the GIX+ strain AKR, had indicated that the Gpd-1 (chromosome 4) and Gv-1 loci are linked at a distance of 19 units from one another. New data from other crosses show that this association of Gpd-1 (glucose-6-phosphate dehydrogenase 1) and GIX phenotypes also constitutes quasi-linkage, evidently due to heterozygosity at the Fv-1 locus. An important theoretical consequence of quasi-linkage in general is that it should enhance the heritability of particular constellations of unlinked genes, and so influence population structure. Our new data are discussed from the viewpoint that MuLV genomes are apparently concerned in quasi-linkage, and therefore by the same arguments may influence the genetic structure of populations. This in turn may strengthen the view that integrated MuLV genomes are not simply intruded into a self-sufficient cellular genome, but are themselves elements of the cellular genome with primary functions, perhaps in reproduction or embryogenesis.

Animals↗
PubMed1976

HLA-D antigen of Japanese origin (LD-Wa) and its association with Vogt-Koyanagi-Harada syndrome.

One homozygous cell "Wa" for HLA-D alleles, associated with HLA-Bw22J (Japanese specific variant of HLA-Bw22), was found in a Japanese family. The HLA-D antigenic specificity defined by this cell has been tentatively named LD-Wa. Phenotype frequency of LD-Wa in the Japanese population was 0.16 (13/81). HLA-D typing for LD-Wa was performed in patients with the Vogt-Koyanagi-Harada syndrome (Harada's disease) with which Bw22J is strongly associated (15/35, 42.9%; corrected P less than 0.02). LD-Wa was presented in 22 of 33 patients (33.7%; P less than 0.0000003). The association of LD-Wa with Harada's disease was stronger than that of Bw22J, and this implies that there might be one of the disease susceptibility gene loci affecting the development of this disease more closely linked to an HLA-D gene locus than the HLA-B locus.

Epitopes↗
PubMed1976

Immune response gene (Ir-SRBC) exerts its effect via macrophages in inbred rats.

In the previous report, strain differences of inbred rats were investigated in the antibody response to sheep erythrocytes (SRBC). A low-responder strain (Fischer rats) produced only IgM antibody, but other high-responder strains switched over from IgM to IgG antibody to SRBC. Pretreatment with incomplete Freund's adjuvant made Fischer rats a high-responder. These results seemed to indicate that there are malfunctions of macrophages, together with T cells, in Fischer rat strain. In this report, strain differences in the phagocytic activity of macrophages were examined using radiolabelled SRBC. High uptake of SRBC by the spleen in the low responder rats, and vice versa, was confirmed in various experimental conditions. Genetic analyses were made of the specific spleen uptake of the radiolabelled SRBC in backcrossed rats. The result clearly showed that the degree of spleen uptake of the radiolabelled SRBC is genetically determined by a single gene and this property itself has a close negative correlation with the ability of each rat to produce haemolysin against SRBC. These results strongly suggest that the Ir-SRBC gene exerts its effect, at least in part, via macrophages. The relationship between the function of the macrophage and the antibody response is discussed.

Animals↗
PubMed1976

HLA antigens in Japanese populations.

HLA antigens in 841 healthy, unrelated Japanese from nine widely separated geographic localities were studied. The five most common antigens observed in order of decreasing frequency were for the HLA-A locus: HLA-A9, A2, A10, AW32 and A11; and for the HLA-B locus: HLA-'B5' (= HLA-B5+B17), BW40, B12, B14 and B8. The allelic frequency of undetected antigens of the HLA-A locus was .14-.37, and that of the HLA-B locus, .32-.67, indicating that there were serological difficulties in typing for Japanese antigens using antisera from Caucasians. Marked gene frequency clines were observed for HLA-A9 and HLA-A2 from south (Okinawa) to north (Nagoya). Two haplotypes, HLA-A9, B5 and HLA-A10, BW40 were shown to be in linkage disequilibrium in four of the nine subpopulations.

Alleles↗
PubMed1976

High HL-A5 frequency in Behçet's disease.

HL-A antigens of 35 patients with Behçet's disease and 36 normal Japanese were determined by a standard microlymphocytotoxicity test. The frequency of HL-A5 among patients was significantly higher than the controls. No significant differences were observed in the distribution of other HL-A antigens.

Adolescent↗
PubMed1975

Chemical synthesis and sequence studies of deoxyribooligonucleotides which constitute the duplex sequence of the lactose operator of Escherichia coli.

We have synthesized the deoxyribooligonucleotide fragments, constituting the sequence of the lac operator of Escherichia coli. Two of these fragments, d(pApApTpTpGpTpTpApT) (nonamer) and d(pApApTpTpGpTpGpApG) (nonamer), corresponding to the 5' termini of lac operator have been synthesized by the phosphodiester method. The remaining four fragments, d(ApCpApApTpT) (hexamer), d(ApTpApApCpApApTpT) (nonamer), d(ApApTpTpGpTpGpApGpCpGpG) (dodecamer), and d(ApApTpTpGpTpTpApTpCpCpGpCpTpC) (pentadecamer), have been synthesized by an improved phosphotriester method. All of the compounds were first characterized by venom and spleen phosphodiesterase digestion to obtain their base composition. The sequence of these oligonucleotides was fully confirmed by the characteristic mobility shifts of their partial venom phosphodiesterase digestion products on two-dimensional homochromatography. A comparative study of the two methods for the synthesis of oligonucleotides has revealed that the phosphotriester method is more convenient than the phosphodiester method because of higher yields and ease of handling large scale preparations.

Base Sequence↗