By Catherine Freed

I decided to rewrite the third abstract and title from our writing workshop 2- the way it was originally written had really bothered me!


Use of Silicon Rubber Cast Impressions to Delineate Metabolic and Environmental Factors Altering Stomatal Aperture

Stomata are specialized pores lining undersides of leaf cuticles and are crucial for transpiration and drought tolerance. Stomatal aperture was presumed to be controlled osmotically through starch synthesis and degradation in the guard cells. Recent evidence suggests there are many metabolic factors at play, in addition to osmosis, in both guard cells as well as other specialized cells and tissues. Understanding the various factors dictating stomatal physiology and biochemistry, while important, are difficult to study based on deficiencies in technology, parameter variations, and delineating other factors controlling their physiology. By casting leaves in silicone rubber, our lab has been able to measure stomatal aperture without drastically altering leaf environment and morphology. This new approach yields highly reproducible results as well as allows researchers to gauge stomatal aperture under a variety of conditions which would have been difficult to test otherwise. These include measuring stomatal aperture after introduction of leaf inhibitors as well as gauging differences in aperture with various changes in temperature. Ultimately, the use of silicone rubber cast impressions is a cutting edge technique, allowing delineation of various factors controlling stomatal aperture to understand different metabolic factors contributing to guard cell volume.


Some Effects of Metabolic Inhibitors, Temperature, & Anaerobic Conditions on Stomatal Movement

It now appears abundantly clear, not just in the grasses, that the mechanisms of stomatal movement through the changes in volume of the guard cells can no longer solely be considered in terms of the classical osmotic effects controlled merely by the synthesis or hydrolysis of starch, but rather instead it must be considered that the extent of stomatal opening in leaves is the resultant of many different metabolic activities in the guard cells and elsewhere in other cells and tissues. Nevertheless, investigations into the physiology and biochemistry of stomatal action can, of course, provide valuable indications of the manner in which the balance between the reactions concerned with the opening and the closing of the stomata are controlled, particularly if unequivocal data are available to be analyzed on the response of stomata to such factors as enzyme inhibitors, temperature, and oxygen. Unfortunately, it is precisely in these areas where there is most disagreement in the literature: disagreement which often reflects on the technical difficulties, parameter variations and other factors that affect the control of stomatal aperture. Using a newly developed technique involving impressions cast in silicone rubber permits measurements of stomatal apertures without significant alteration of the leaf environment, to obtain essentially identical samples of tissue, providing obvious advantages in experiments in which it is desired to introduce inhibitors into the leaf, or to study the effects of differences in the temperature of the gas phase.