Detailed organic analysis of natural aerosols from the Amazonian rain forest showed considerable quantities of previously unobserved polar organic compounds, which were identified as a mixture of two diastereoisomeric 2-methyltetrols: 2-methylthreitol and 2-methylerythritol. These polyols, which have the isoprene skeleton, can be explained by OH radical-initiated photooxidation of isoprene. They have low vapor pressure, allowing them to condense onto preexisting particles. It is estimated that photooxidation of isoprene results in an annual global production of about 2 teragrams of the polyols, a substantial fraction of the Intergovernmental Panel on Climate Change estimate of between 8 and 40 teragrams per year of secondary organic aerosol from biogenic sources.

https://science.sciencemag.org/content/sci/303/5661/1173.full.pdf

Formation of Secondary Organic Aerosols Through Photooxidation of Isoprene

A fellow of my acquaintance, on seeing a colleague drink undiluted water (55.5 molal), has been known to comment in disapproval that water at such a concentration should not be used for that purpose and that its main function is for putting around the outside of boats. He conceded that dilution with a little salt is acceptable for boats but for no other purpose. The proponent of this philosophy is not a biologist and it is unlikely that many biologists would accept his generalization without some qualification. Nevertheless, it is a point of view. Another point of view with which all biologists might not agree, at least initially, is one which I wish to advance in this review. It is that, notwithstanding the indispensability of water in living systems and the unique properties of solvent water, quantitative variations in the amount of water available are of less direct microbiological significance than is generally conceded.

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=1991&context=smhpapers

Microbial water stress.

It is shown that in the majority of higher plant halophytes examined proline is the major component of the amino acid pool in plants collected from the field. In Triglochin maritima L. free proline can represent 10-20% of the shoot dry weight. Under non-saline conditions proline levels are low and increase as the salinity is raised. Comparisons of inland and coastal populations of Ameria maritima Willd. suggest that the capacity to accumulate proline is correlated with salt tolerance. It is suggested that proline functions as a source of solute for intracellular osmotic adjustments under saline conditions.

The role of proline accumulation in halophytes.

Publisher Summary This chapter emphasizes the measurement of plant water potential following the realization of the importance of atmospheric demand in determining plant water deficits. The total water potential concept determines the movement of water through the soil-plant-atmosphere continuum in response to gradients in water potential and of the soil, plant, and atmospheric factors that influence the development of water deficits in plants. A water deficit occurs whenever water loss exceeds absorption. The use of total water potential as the best single indicator of plant water status has its limitations while attempting to understand the effect of water deficits on the various physiological processes involved in plant growth. The chapter discusses the effects of water deficits on crop growth, crop development, and crop yield. The differences in response of plants grown under controlled conditions and in the field are discussed. Some difficulties in extrapolating from controlled environments to the field are presented in the chapter.

Crop Water Deficits

Regulation of trehalose mobilization in fungi.

CONTENTS PAGE INTRODUCTION I. . . . . 44 FUNGI . . . . . . . . . . . 144 Occurrence and quantitative variation . . . . . I44 Metabolism and physiological role . . . . . . 148 Uptake and utilization . . . . . . . 148 Polyols as natural substrates . . . . . .I49 Polyols as storage products . . . . . . I50 Polyols in spores and spore germination . . . . I51 Intermediary metabolism and enzymology . . . . I53 The role of polyols in storage of reducing power and coenzyme regulation . . . . . . . . . . 56 The control of polyol synthesis . . . . . .I57 ALGAE . . . . . . . . . . . I57 Occurrence and quantitative variation . . . . . 157 Phaeophyta . . . . . . . . . I59 Rhodophyta . . . . . . . . .I6I Chlorophyta . . . . . . . i6I Chrysophyta and Pyrrophyta . . . . . i6i Heterotrophic growth . . . . . . . . i6I Metabolism and physiological role . . . . . . i62 Phaeophyta . . . . . . . . . i62 Other phyla . . . . . . . . .I63 LICHENS . . . . . . . . . . . I64 Occurrence and quantitative variation . . . . . I64 Metabolism and physiological role . . . . . . i66 Accumulation of polyols during photosynthesis . . . i66 Uptake . . . . . . . . . . I67 Endogenous metabolism . . . . . . . I67 HIGHER PLANTS . . . . . . . . . i68 Occurrence and quantitative variation . .. . . I68 Metabolism and physiological role I. . . . . 70 Photosynthesis and translocation . . . . . . I70 Enzymology . . . . . . . . 171 Endogenous metabolism . . . . . . I73 Heterotrophic nutrition . . . . . . . I74 DISCUSSION . . . . . . . . . . 175 Occurrence and quantitative variation . . . . . 175 Carbohydrate storage . . . . . . . . 175 Translocation . . . . . . . . . 176 Osmo-regulation . . . . . . . . . I77 Enzymology and control of synthesis . . . . . 177 Coenzyme regulation and storage of reducing power . . I78 Conclusions . . . . . . . . . I78 ACKNOWLEDGMENTS I. . . . . 78 REFERENCES . . . . . . . . . . I79

D. H. Lewis

Papers

Sugar alcohols (polyols) in fungi and green plants