Search PubMed⌕ Search

Biomedical subjects

S Kamisaka

Publications and source records attributed to S Kamisaka.

41 records · Page 3Linked to original sources
PubMed1995

Morphogenesis and cell wall changes in maize shoots under simulated microgravity conditions.

Various plant organs show a spontaneous curvature on a three-dimensional clinostat. Changes in the cell wall metabolism underlying the curvature were examined in maize shoots. In coleoptile nodes, no differences were detected in either the level or the composition of cell wall polysaccharides between the convex and the concave halves. However, the convex side showed a higher activity of (1 --> 3),(l --> 4)-beta-glucan breakdown, which appears to be associated with the curvature. In the elongating region of coleoptiles, the accumulation of wall polysaccharides occurred in the convex side. There was no significant difference in the glucanase activity between both sides. Thus, the spontaneous curvature in different regions of maize shoots may be brought about through different mechanisms under simulated microgravity conditions.

Cell Wall↗
PubMed1993

Vegetative growth of higher plants on a three-dimensional clinostat.

Seedlings of rice, maize, cress, pea, and azuki bean were grown on a three-dimensional clinostat and changes in their vegetative growth processes were analyzed. A balanced relationship among the length or the weight of each organ was observed in these species even on the clinostat. Growth of pea second internodes is supported by the transport of sugars from the cotyledons, which was not influenced by the clinostat rotation. Thus, growth correlation and the translocation of sugars normally occurred even under simulated microgravity conditions. In contrast, morphogenesis was clearly changed by the clinostat rotation. The axiality along the gravity vector disappeared and so seedlings formed themselves into a sphere-like shape on the clinostat. The dorsiventrality was indistinct in growth of maize coleoptiles on the surface of the earth, but the clinostat rotation induced a clear dorsinventral bending. These changes in morphogenesis may influence the long-term growth phenomena and modify the life cycle of higher plants under a microgravity environment.

Biological Transport↗
PubMedDate not supplied

Changes in the rheological properties of the cell wall of plant seedlings under simulated microgravity conditions.

In this review article, we discuss the changes in the mechanical properties of the primary cell wall of different organs of several species of plant seedlings grown under simulated microgravity conditions. We compared growth and tropistic responses of these organs growing under different microgravity conditions, namely: 1) 3-D clinostat (three-dimensional clinostat with two axes); 2) water-submergence for rice seedlings, and 3) for comparison, an accelerated gravity using a specifically designed centrifuge. We measured the minimum stress-relaxation time as the parameter representing the mechanical property of the cell wall. We also measured extensiblity, in mm/g. The 3-D clinostat condition disturbed the normal gravitropic response of organs but affected growth rate and mechanical properties of the cell wall very little. Water-submergence of rice seedlings caused an acceleration of coleoptile elongation in the dark and caused a marked change in the mechanical property of the cell wall. However, the additional gravity of 30-135 xg showed only a small effect on growth and the mechanical property of the cell wall.

Biomechanical Phenomena↗