Chemical Ecology

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What is chemical ecology?

From studies of the environment’s effect on species (e.g. animal and plants) or the adaptation of species to the environment, evolves a branch of science defied as ecology. Natural products play a fundamental role in the coexistence of species in the ecosystem. Therefore as a result a new branch of biology was developed known as the chemical ecology or ecological chemistry. Chemical ecology describes relationships or interactions between species, which can be related to an effect of naturally produced compounds.


Adaptation to the environment

Temperature

To tolerate low temperatures, it has been found that insects and plants synthesize glycol as antifreeze substances. It is a metabolic adjustment developed by them to freezing (e.g. the green algae Dunaliella parva is reported to accumulate as much as 70% glycol by dry weight). It seems that they have exploited this method long before we applied it to our automobile engines. Increased concentrations of carbohydrates such as glucose, fructose, sucrose and mannitol also were found to make the plants more frost- resistant. Some macromolecules also found to prevent crystallization of water.

There are some microorganisms (e.g. bacteria) which have adapted to conditions in hot springs as high as 800C also. But plants are generally sensitive even to moderate heat changes up to 40-50 0C, but they adjust to these temperatures by rapid synthesis of novel heat resistant proteins with a M.W of 70,000-90,000 Daltons.

1 amu = 1 Dalton


Drought

In plants adapted to drought, the amino acid proline is found to be more abundant. This could be due to a special osmotic effect of the amino acid.

The opening and closing of stomata (special pores in the leaves) are hormonally controlled by the level of abscisic acid and some related sesquiterpenoids. It has been observed that the concentration of abscisic acid increased considerably during wilting of whet plants, but with a sufficient supply of water returned to normal.


Salinity

Plants respond to salinity (chemical salt) by accumulating proline (e.g. in America maritime). As in drought resistant plants an osmotic mechanisms has been proposed. Organic sulphates and other organosulphur compound are also found wide spread in marine plants e.g. sulphoniumbetaine is isolated from the green algae Ulva lactua and the flavone isolated from Zostera marina. Algae are also reported to be rich in polyols, mannitol, sorbitol and glycerol. These compounds have both osmotic and antifreeze function.




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