Gravitational biology and space life sciences: current status and implications for the Indian space programme.

This paper is an introduction to gravitational and space life sciences and a summary of key achievements in the field. Current global research is focused on understanding the effects of gravity/microgravity onmicrobes, cells, plants, animals and humans. It is now established that many plants and animals can progress through several generations in microgravity.

Structural and histochemical studies on grain-filling in the caryopsis of rice (Oryza sativa L.).

The endosperm and embryo that constitute the filial tissues of rice caryopsis are isolated from the maternal tissues by the absence of any symplastic continuity. Nutrients are transported to the endosperm through a single ovular vascular trace present on the ventral side of the ovary. Initially solute enters through the chalaza into the nucellar projection and then into the endosperm.

Response to gravity by Zea mays seedlings. I. Time course of the response.

Gravistimulation induces an asymmetric distribution of free indole-3-acetic acid (IAA) in the cortex-epidermis of the Zea mays L. cv 'Stowells Evergreen' mesocotyl within 15 minutes, the shortest time tested. IAA was measured by an isotope dilution method as the pentaflurobenzyl ester.

Analysis and significance of gravity-induced asymmetric growth in the grass leaf-sheath pulvinus.

The negative gravitropic response in the grass leaf-sheath pulvinus is a consequence of cell elongation involving all cells except those of the uppermost region of the upper flank of an horizontally oriented pulvinus. The lowermost layer of cells elongate maximally, and the regions in between elongate to intermediate extents. The resulting curvatures of a responding pulvinus can be expressed mathematically by relating the angle of curvature (theta) to the original length (L0) and the maximal length of the lower surface (L1) and the diameter of the organ (D), using the equation, theta = (L1-L0)/D, where theta is in radians.

Role of Indole-3-acetic Acid and Gibberellin in the Control of Internodal Elongation in Avena Stem Segments: Long Term Growth Kinetics.

Exogenous application of indoleacetic acid results in a significant suppression of the linear growth that is promoted by exogenous gibberellic acid in Avena stem segments in a fashion similar to that previously noted in Avena leaf base segments (van Overbeek and Dowding, 1961, Fourth International Conference Plant Growth Regulation). Treatment with the auxin transport inhibitors, methyl-2-chloro-9-hydroxyfluorene-(9)-carboxylate (CFM) or 2,3,5-triiodobenzoic acid (TIBA), alone promotes elongation growth of the stem segments over that of control growth. This effect is interpreted as being due to the interference in the transport of native indoleacetic acid by CFM and TIBA, thus removing the inhibitory effect of native indoleacetic acid on gibberellin-promoted growth in the internodal intercalary meristem.