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Biomedical subjects

S Ohno

Publications and source records attributed to S Ohno.

At least 973 records · Page 54Linked to original sources
PubMed1978

Chromosome changes (trisomy 15) in murine T-cell leukemia induced by 1,12-dimethylbenz(a)anthracene (DMBA).

The banding pattern of DMBA-induced leukemias in C57BL/6 mice revealed a very constant chromosome pattern: the presence of trisomy 15 in almost all leukemic cells. This finding strongly suggests that chromosome 15 trisomy is the first detectable specific chromosome change associated with the development of DMBA-induced T-cell lymphomas. A similar association was previously shown with regard to development of radiation-leukemia-virus-induced T-cell lymphoma. It is conceivable that in tumors of diverse etiologies common cytogenetic changes may appear in the same common target-cell precursor, by a process of the "convergent microevolution" type.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

A modified wire-loop method for quantitative electron microscopic radioautography.

A simplified method of emulsion coating and development for quantitative electron microscopic radioautography without any special instrument in introduced. Seven grids carrying ultrathin sections are attached to a glass block with double-coated Scotch tape. They are coated with a wire-loop, 2.5 cm in diameter. Ten glass blocks are then stuck on a slide, exposed, developed, fixed and stained simultaneously. Employing this method, the emulsion coating and the following procedures are easily accomplished under an identical condition.

Autoradiography↗
PubMed1978

The role of H-Y antigen in primary sex determination.

The basic embryonic plan of mammals is inherently feminine. Male development is due to two-step interventions of this basic plan: the Y chromosome directs the embryonic indifferent gonad to organize a testis instead of an ovary; the Y-organized testis synthesizes and secretes testosterone, which induces all the extragonadal masculine development. The Y chromosome plays no direct and appreciable role in extragonadal masculine development. Testicular organization, normally under the direction of the Y, is the function of the evolutionary conserved plasma membrane protein serologically detectable as H-Y antigen. Under specific circumstances, H-Y antigen may be expressed in the absence of the Y chromosome, thus producing XO and XX males. If H-Y antigen is not expressed, XY individuals develop as females. H-Y antigen is the first plasma membrane or cell surface protein to which a specific organogenesis function has been assigned.

Adolescent↗
PubMed1978

Two plasma membrane antigens of testicular sertoli cells and H-2-restricted versus unrestricted lysis by female T cells.

Sertoli cell-only seminiferous tubules of sterile XX,Sxrl-male mice served as an excellent source of pure Sertoli cells. When H-2-compatible female mice were immunized 3 times with these Sertoli cells, resulting antibodies recognized two antigens on the plasma membrane of testicular Sertoli cells. They were male-specific, but ubiquitously expressed H-Y antigen and the cell lineage-specific antigen which Sertoli cells shared with ovarian follicular cells. Doubly primed (2 or 3 times in vivo, and once in vitro) cytotoxic T cells from these females lysed target Sertoli cells in both H-2-restricted and nonrestricted manners. While H-2-restricted killings were attributable to H-Y antigen, further work is needed to identify the Sertoli follicular cell lineage-specific antigen as the cause of H-2-nonrestricted killings.

Animals↗
PubMed1978

The HLA-dependent expression of testis- organizing H-Y antigen by human male cells.

The proposal that the stable expression of organogenesis-directing plasma membrane antigens, such as testis-organizing H-Y antigen, requires beta2-microglobulin-MHC antigen dimers as anchorage sites was tested on Daudi human Burkitt lymphoma cells [46, XY, 15q-, 14q+, beta2-m(-), HLA(-)]. The H-Y antigen level of Daudi was only 20% of that of Raji and Ramos, two human male pseudodiploid Burkitt lymphoma lines that were beta2-m(+), HLA(+). When Daudi is hybridized with beta2-m(+), HLA(+) cell lines, beta2-microglobulin, supplied by the latter, is known to restore the expression of Daudi HLA antigens A10 and BW17. Such restoration of HLA antigen expression markedly elevated H-Y antigen levels in those somatic hybrids. Thus the H-Y antigen level of the Daudi x Raji 8A (male X male) hybrid became equal to that of TetraRaji--the colcemide-induced Raji tetraploid line. Two independently derived Daudi x Hela D98 (male x female) hybrids, DAD 1 and DAD 10, demonstrated even higher H-Y antigen levels comparable to that of normal male peripheral blood lymphocytes.

Antigens↗
PubMed1978

Chromosome changes (trisomies #15 and 17) associated with tumor progression in leukemias induced by radiation leukemia virus.

An experimental system was developed that permitted nonrandom chromosome changes that occur in radiation leukemia virus (RadLV)-induced lymphomas to be followed during tumor progression. RadLV variant-induced preleukemia and leukemia cells originating from female inbred C57BL/6 mice were injected into male animals of the same strain. Since all donors were females and all recipients were males, the sex chromosome complements (XX and XY) were used to distinguish the preleukemia and leukemia cells from those of host origin. The G-banding analysis revealed that more than 50% of animals that were inoculated with preleukemia cells and that developed leukemia possessed tumor stem-lines of 41 chromosomes with a tristomy of chromosome #15. In animals inoculated with overt leukemia cells and in which tumor progression occurred, the G-banding an additional trisomy of chromosome #17. The cytogenic data strongly suggested that the trisomy of chromosome #15 was the first specific tumor-associated chromosome change that occurred in the process of conversion of RadLV-induced preleukemia cells to fully autonomous tumor cells.

Animals↗
PubMed1978

Colicin E3 is an endonuclease.

It was confirmed by polyacrylamide gel electrophoresis that isolated 16S rRNA was cleaved by the active component (protein A) or the active fragment (T2A) of colicin E3. However, the degradation was random, in contrast with the specific cleavage observed in the interaction of colicin E3 with ribosomes. Furthermore, the active component and the active fragment had low activities, and far greater amounts of these materials were required for degradation of the isolated rRNA than for ribosome inactivation. The degradation of rRNA cannot be due to contaminating ribonuclease(s), but is due to colicin E3 itself, because of the following facts. (1) Protein B of colicin E3, which specifically inhibits the ribosome-inactivating activity of colicin E3, inhibited the degradation of rRNA. (2) Protein B of colicin E2, which inhibits the action of colicin E2 but not of colicin E3, failed to inhibit the degradation of rRNA. (3) The activity appeared in the peak of protein A or fragment T2A, respectively, when they were rechromatographed on Sephadex G-75.

Colicins↗
PubMed1978

Testicular cells lysostripped of H-Y antigen organize ovarian follicle-like aggregates.

A suspension of free testicular cells were obtained by mild trypsin treatment from newborn BALB/c testes, and their plasma membrane H-Y antigen sites were blocked (lysostripped) by an excess of H-Y antibody of proven specificity and potency (45 min in ice). Upon 16 h of the Moscona-type rotation culture, these treated testicular cells yielded primarily spherical aggregates, more than half of which demonstrated a strong resemblance to ovarian follicles. The resemblance was particularly striking between the smallest testicular folliculoids and primordial ovarian follicles that abound in the newborn female gonad. Under the same condition, control serum-treated testicular cells primarily yielded cylindrical tubular structures that can be very long. Over a critical range, concentrations of H-Y antibody apparently influenced the frequency of testicular folliculoid formation. The above directly supports the proposed testis-organizing function of H-Y antigen and is certainly compatible with the genetic situation encountered in the wood lemming (Myopus schisticolor), that in the functional absence of H-Y antigen, XY gonadal cells readily organize an ovary.

Animals↗
PubMed1978

Physical properties of androgen receptors in brain cytosol from normal and testicular feminized (Tfm/y hermaphrodite) mice.

Our previous results had shown that brain cytosol from androgen-insensitive, testicular feminized (Tfm/y) mice contains a reduced amount (20-25%) of androgen receptors, compared to normal female or castrated male mice, with unchanged affinity for dihydrotestosterone (DHT). We have now used various physicochemical techniques to ask whether there is a qualitative difference between these residual receptors and those in normal brain. When androgen receptors labeled with [3H]DHT in concentrated crude brain cytosol were analyzed by density gradient centrifugation and Agarose gel filtration in buffers containing 0.4-0.5 M KCl, Tfm/y receptors appeared to be smaller and more symmetrical than those from their normal siblings; however, if wild-type receptors were partially purified or prepared from slightly more dilute homogenates, their properties approached those of Tfm/y receptors in crude cytosol. This suggested that receptor molecules in concentrated cytosol from normal mice were aggregated to a greater extent than were those from the mutant. The molecular weight (54,000) and axial ratio (3:1 for prolate or oblate ellipsoid) calculated for Tfm/y receptors, therefore, may provide estimates for normal receptors as well. By DNA-cellulose chromatography, Tfm/y and female cytosol receptors were both resolved into two components, eluting at about 0.13-0.15 and 0.22-0.24 M NaCl. On DEAE-cellulose columns, both were eluted as a single major species at approximately 0.08-0.10 M KCl. Thus, excluding their state of aggregation, presumably resulting from their different concentrations in crude cytosol, Tfm/y and normal receptors were substantially identical as concerns the physical parameters examined in this study.

Androgen-Insensitivity Syndrome↗
PubMed1978

A hypoglossal reflex elicited by mechanical stimulation of the mandibular mucosa in the cat.

Electromyographic responses of extrinsic tongue muscle motor units to innocuous mechanical stimulation of the mandibular mucosa were studied in urethane-chloralose anesthetized cats. The mechanical stimulation either excited or inhibited spike discharges in some extrinsic tongue muscle motor units when applied to the alveolar gingival musosa on the lingual side. Excitatory receptive fields of styloglossal motor units were predominantly ipsilateral, and the molar and second premolar gingivae were the most effective. In contrast, excitatory receptive fields of hyoglossal motor units were predominantly contralateral, the molar gingiva being most effective. In genioglossal motor units, only the ipsilateral alveolar gingiva was excitatory, while ipsi- and/or contralateral alveolar gingivae were inhibitory. The inhibitory receptive field was located in the molar and/or second premolar alveolar gingivae. When an anesthetic spray was applied to the mucosal surface, the reflex response completely disappeared, indicating its origin to be located in the stimulated gingival mucosa. After cutting the lingual nerve, reflex responses to mechanical stimulation of the premolar and molar gingival mucosa was abolished. It was concluded that the premolar and molar gingival mucosa constitutes a part of the afferent source for the linguo-hypoglossal reflex.

Animals↗
PubMed1978

H-Y antigen in testes of XX(BALB)/XY (C3H) chimaeric male mouse.

Among experimentally produced BALB/C3H aggregation (Blastocyst fusion) chimaeras of the mouse, one fertile XX (BALB)/XY (C3H) male was identified who maintained 50% or more female cells in many parts of his body. Results of H-Y antibody absorption tests revealed an XY to XX transfer of testis-organizing H-Y antigen among testicular Sertoli and Leydig cells, but not among spleen and epidermal cells.

Animals↗