Plants and Animals

ASEN 5016 Lecture 27b: Plant and Animal Research in Space

OBJECTIVES

1. Identify general plant environmental sensing and response mechanisms

2. Describe sensor and signal transduction theories and space flight data / applications

3. Discuss implications of ‘seed-to-seed’ studies

4. Discuss the use of various animal models used for space flight studies

Why Study Plant Gravitropism?

•Fundamental Biology

–Understand the fundamental biology of the plant response to gravity from ‘root’ to ‘shoot’

•Commercial Agriculture Applications

–Apply the findings to products from ‘stronger trees’ to ‘better pharmaceuticals’

•Long Duration Space Mission Life Support

–Apply the findings to technologies from ‘Salad Machines’ to ‘Space Farms’

History

•A. Knight, 1806

–Growth of roots on a spinning wheel

•A. de Candolle, 1834/38

–Movement independent of humidity and light

•A. B. Franck, 1868

–Introduced the term geotropism

1. General Plant Environmental Sensing and Response Mechanisms

Tropisms

Plant Gravitropism (a.k.a geotropism)

•Gravitropism- movement in response to gravity

–Positive (Roots) - move with gravity

–Negative (Shoots) - move away from gravity

–Transversal – Limbs/Lateral Roots

•Other plant movements

–Phototropism (light)

–Thigmotropism (touch)

–Hydrotropism (water)

–Electrotropism (electricity)

–Pneumotropism (pressure)

–Magnetotropism (magnetism)

2. Sensor and signal transduction theories

Physiology of the root tip

Root Cap
Meristematic Region
Elongation Zone

The Sensor - Statocyte

•C. Darwin, 1881

–The root cap as the statenchyma / statocytes

The Sensor - Statolith

•F. Noll, 1892

–Statolith theory (verified by B. Nemec, G. Haberlandt)

Signal Transduction

•Biochemical cascade

–Plants have no nervous system

•Cholodony-Went, 1937

–Growth response due to differential auxin transport

•Evans, 1986

–Calcium involved – exogenous calcium application and inhibitor studies

•Conversion of mechanical movement to biochemical signal

Space Flight

•Modified development of statoliths in microgravity and clinorotation (Smith)

•Redistribution of statoliths during parabolic flight (Sievers)

•Roots grown in microgravity were able to bend when stimulated on a 1g centrifuge although their root cap had never been subjected to gravity or mass acceleration (Perbal)

•Simulation of gravitropism via magnetophoresis (Kuznetsov & Hasenstein)

http://www.spacebio.net/modules/pb_intro.html

Space Applications

· Plant Growth Hardware

· Biological Life Support

3. Seed-to-seed production and viability

LDEF

http://science.nasa.gov/headlines/y2001/ast25jul_1.htm

http://www.spacedaily.com/news/iss-science-02c.html

4. Animal Models

A multicellular organism of the kingdom Animalia, differing from plants in certain typical characteristics such as capacity for locomotion, nonphotosynthetic metabolism, pronounced response to stimuli, restricted growth, and fixed bodily structure.

Used as surrogates for human survival tests initially, now used for testing general space flight human health-related effects (bone, muscle, immunology, etc.).

Dogs, primates, humans, rodents (various other invertebrates and vertebrates)