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C Tokunaga

Publications and source records attributed to C Tokunaga.

34 records · Page 2Linked to original sources
PubMed1996

Activation of RAC-protein kinase by heat shock and hyperosmolarity stress through a pathway independent of phosphatidylinositol 3-kinase.

RAC protein kinase (RAC-PK), a serine/threonine protein kinase containing a pleckstrin homology (PH) domain, was activated by cellular stress such as heat shock and hyperosmolarity. Wortmannin, which is known as a potent inhibitor of phosphatidylinositol 3-kinase and normally inhibits growth factor-induced activation of RAC-PK, did not suppress heat-shock induced activation of RAC-PK, indicating that this stress-induced activation of the kinase is not mediated by phosphatidylinositol 3-kinase. The PH domain was indispensable for stress-induced activation of RAC PK. In heat-treated cells, PKC delta, a member of the protein kinase C family, was found to associate with the PH domain of RAC-PK. This PKC subspecies was phosphorylated in vitro by RAC-PK. The results suggest that RAC-PK may play a role in the cellular response to stress through its PH domain.

3T3 Cells↗
PubMed1976

The effect of growth and joint formation on bristle pattern in D. melanogaster.

Dependence of bristle pattern on size and joint formation was studied for male first leg tarsi of fj (four jointed) and d (dachs) mutants in homozygotes and in mosaics resulting from X-ray induced mitotic recombination. Homozygotes have four tarsal segments, lacking a third tarsal joint in most cases. The two proximal segments are shortened, the first by one-third, and altered in bristle pattern, whereas the distal two segments are little affected. Expressivity of fj is high, and of d is low, for the extent and frequency of joint failure. The longer the second segment, the more complete the third joint and the greater the bristle number. Only the jointed side of the segment approximates two segments in its bristle pattern. Mosaic studies show that joint failure occurs autonomously in fj, or in the majority of d clones, and that joint formation by heterozygous clones is autonomous except in the border area contacting a fj or d spot lacking a joint, in which are a joint failure occurs. Bristle pattern in this jointless heterozygous area switches to that of a single segment. Localized non-autonomy also occurs in the t-rows of heterozygous tissue contacting a fj or d spot. Both mutant genes are interpreted as reducing longitudinal growth of the proximal tarsi, with joint failure as a consequence, and with alterations of bristle pattern resulting directly from size reduction, or indirectly through joint failure.

Animals↗
PubMed1972

Autonomy or nonautonomy of gene effects in mosaics.

The dominant autosomal gene Msc (Multiple sex combs) of Drosophila causes the appearance of sex combs on the second and third legs and a reduction of size of sex combs on first legs. The effect of Msc was studied in mosaic flies in which non-Msc spots were present on a Msc background. Mosaics were due to somatic crossing-over induced by x-rays. Analysis of mosaics suggested autonomy of the action of Msc, provided that the somatic crossing-over occurs less frequently proximally to the Msc locus than distally. This unusual ratio of somatic crossing-over was confirmed by a separate experiment with the gene Kinked, whose locus is very close to Msc.

Animals↗
PubMed1971

On cell lethals in Drosophila.

Somatic crossing over in flies heterozygous for a dominant Minute mutant may result in two cells, homozygous for wild type and Minute, respectively. If both cells took part in development, a twin spot of two genotypes, different from the rest of the body, would result. Two-hundred wild type spots were found, none of which was accompanied by an adjacent twin spot homozygous for Minute. The absence of these spots shows that their cell lethality is not overcome by transport, including diffusion, across a few cells of gene-dependent material from the neighboring cells which carry one or two wild type alleles of Minute.

Alleles↗