Temperature ecological principles

Figure 1 Correlation of NPP (in units of biomass) with temperature and precipitation (Schuur, 2003) (reproduced by permission of Springer from Principles of Terrestrial Ecosystem Ecology, 2002).

Owing to its intermediate position between GC and LC, SFC can be performed equally well in open capillaries and packed columns. The separation can be influenced by the type of stationary phase and of modifier, by pressure, pressure drop, and temperature. In contrast to GC, SFC can also be used for the separation of nonvolatile or thermally labile compounds (although some temperature compatibility is necessary). The separation of enantiomers on chiral stationary phases can be very attractive because the temperature is lower than in GC, which increases the separation factors. SFC is an alternative to normal-phase LC because it is fast and carbon dioxide is ecologically sound. An example of an SFC separation can be found in the previous article. Principles, where Figure 2 shows the separation of orange oil components. 

In principle, use of tissue cultures in well defined media under controlled conditions (illumination, temperature, etc.) represents a technique ideal for obtaining reproducible information on plant biochemistry, undisturbed by climatic and ecological variables. One important question is whether undifferentiated cells produce the same enzyme systems and the same secondary metabolites as intact plants. The answer probably depends on the compound(s) of interest and on the culture conditions. Recent work illustrates the importance of this research area, whose successes promise to provide new tools for the study of biosynthetic pathways leading to polythiophenes. 

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