Masao Mori

The complete sequence of the rice (Oryza sativa) chloroplast genome: Intermolecular recombination between distinct tRNA genes accounts for a major plastid DNA inversion during the evolution of the cereals

SummaryThe entire chloroplast genome of the monocot rice (Oryza sativa) has been sequenced and comprises 134525 bp. Predicted genes have been identified along with open reading frames (ORFs) conserved between rice and the previously sequenced chloroplast genomes, a dicot, tobacco (Nicotiana tabacum), and a liverwort (Marchantia polymorpha). The same complement of 30 tRNA and 4 rRNA genes has been conserved between rice and tobacco. Most ORFs extensively conserved betweenN. tabacum andM. polymorpha are also conserved intact in rice. However, several such ORFs are entirely absent in rice, or present only in severely truncated form. Structural changes are also apparent in the genome relative to tobacco. The inverted repeats, characteristic of chloroplast genome structure, have expanded outward to include several genes present only once per genome in tobacco and liverwort and the large single copy region has undergone a series of inversions which predate the divergence of the cereals. A chimeric tRNA pseudogene overlaps an apparent endpoint of the largest inversion, and a model invoking illegitimate recombination between tRNA genes is proposed which accounts simultaneously for the origin of this pseudogene, the large inversion and the creation of repeated sequences near the inversion endpoints.

The Evolution of Dwarf Galaxies with Star Formation in an Outward-propagating Supershell

We simulate the dynamical and chemical evolution of a dwarf galaxy embedded in a dark matter halo, using a three-dimensional N-body/smoothed particle hydrodynamics (SPH) simulation code combined with stellar population synthesis. The initial condition is adopted in accord with a 1010 M☉ virialized sphere in a 1 σ cold dark matter perturbation which contains 10% baryonic mass. A supersonic spherical outflow is driven by the first starburst near the center of the galaxy and produces an expanding supershell in which stars are subsequently formed. Consecutive formation of stars in the expanding shell makes the stellar system settled, with the exponential brightness profile, the positive metallicity gradient, and the inverse color gradient in agreement with observed features of dwarf galaxies. We therefore propose that the energy feedback via stellar winds and supernovae is a decisive mechanism for formation of less compact, small systems like dwarf galaxies.

Effects of Glycinin Acidic A1a Subunit on Insulin-Involved Cellular Metabolism in Rat Adipocytes and 3T3-L1 Cells

Glycinin acidic A1a subunit (A1a) and its trypsinized products (A1a/Try) were found to potentiate the insulin-mediated antilipolysis antagonized to isoproterenol in rat epididymal adipocytes and cultured 3T3-L1 cells. Moreover, A1a/Try enhanced the insulin-mediated glucose transport in rat adipocytes. On the other hand, the chymotryptic product of A1a (A1a/Chy) had no effect on the insulin action. A possible explanation is offered for the mechanism of A1a action.