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"Firn, Richard"
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Bioprospecting – why is it so unrewarding?
Some economic analyses have placed high values on the chemicaldiversity residing in threatened habitats[, Conservation Biology 6:128-130; , InBiodiversity and its Importance to Human Health, Columbia University Press, NewYork; , Journal of PoliticalEconomy 108: 173-206]. Consequently, bioprospecting (searching for newbiologically active chemicals in organisms) is considered by some to be a way offunding the preservation of biodiversity, especially in the less developedcountries. However, the large multinational pharmaceutical andagrochemical companies spend very little of their research effort onbioprospecting [, Phytochemistry55: 463-480]. Why is this? The answer lies in the fact that any chemical(whether a synthetic or a natural product) has a very low probability ofpossessing useful biological activity. The common belief that every naturalproduct has been selected by its producer such that only biologically activenatural products are made is not correct. Given that random collections ofsynthetic or natural products have a similar chance of containing a chemicalwith specific activity against any one target, and given that syntheticchemicals are nearly always much easier to synthesise on an industrial scale, itis predictable that major agrochemical and pharmaceutical companies will devoteonly a limited amount of their R & D budget to bioprospecting. Although argued that scientificadvances will make bioprospecting more cost-effective in future, an alternativescenario is presented where current biotechnological developments will furthererode the value of bioprospecting. It is concluded that there should be noreliance on large-income streams being available from bioprospecting agreementsto help fund the preservation of biodiversity.[PUBLICATION ABSTRACT]
Journal Article
Plant Intelligence: an Alternative Point of View
The concept of plant intelligence has been advanced by Trewavas as a potentially useful framework to guide those seeking to understand plant growth and development. In this short critique, the validity of this concept is critically assessed. Central to this critique is the proposition that the concept of the individual, to which intelligence and behaviour are intimately linked, cannot usefully be applied to plants. It is argued that the adaptive responses of plants are best appreciated if the importance of the autonomy of the individual organs is acknowledged. Although Trewavas does acknowledge the autonomy of organs by describing an individual plant as being ‘a democratic confederation’, that terminology implies a complexity to the interaction between organs which would demand a cogitative ability beyond that actually demonstrated in plants. It may be more appropriate to consider a plant as operating normally as a simple economic federation of many specialized economies (organs and cells). Occasionally, there can be a dramatic, and sometimes complex, reshaping of the economic balances, with the result that the fate of some or many of the individual cells will change. However, such major changes in growth and development are driven by a few simple events in an individual organ and cells. These driving events are more akin to small local revolutions in individual states than they are to democratic decisions in a sophisticated confederation.
Journal Article
On the Evolution of Plant Secondary Chemical Diversity and Discussion
A common-sense evolutionary scenario predicts that well-defended plants should have a moderate diversity of secondary compounds with high biological activity. We contend that plants actually contain a very high diversity of mostly inactive secondary compounds. These patterns result because compounds arising via mutation have an inherently low probability of possessing any biological activity. Only those plants that make a lot of compounds will be well defended because only high diversity confers a reasonable probability of producing active compounds. Inactive compounds are retained, not eliminated, because they increase the probability of producing new active compounds. Plants should therefore have predictable metabolic traits maximizing secondary chemical diversity while minimizing cost. Our hypothesis has important implications to the study of the evolution of plant defence.
Journal Article
Solving the puzzle of gravitropism--has a lost piece been found?
Attempts to devise models to account for the gravitropic behaviour of plant organs have been limited conceptually by the predominance of studies on the gravitropic behaviour of organs of young seedlings. The dramatic growth responses induced by gravitropic stimulation of young shoots or roots, which rapidly restore the elongating axes to vertical, are experimentally convenient but theoretically limiting because gravitropism needs not simply restore an organ to vertical. Evidence is reviewed that suggests that plant organs must possess a mechanism which will allow them to attain a stable gravitropic position at any angle and that each organ has a characteristic gravitropic set-point angle (GSA). The GSA can be changed developmentally and is also regulated in a reversible manner by environmental parameters such as light. It is speculated that gravity may itself influence the GSA of an organ. The recognition that plant organs can grow at angles other than vertically up or down is not new, but previously it has been accepted that angles other than vertical were the consequence of the vectorial resultant effect of two different. opposing mechanisms. The new GSA concept proposes that a single mechanism might be sufficient to account for all forms of gravitropism in roots and shoots. This unifying concept proposes that the ability to change the angle of an organ with respect to the vertical is part of the basic gravitropic mechanism and that models of gravitropism must be able to account for this important feature.
Journal Article
The use of mutants to probe models of gravitropism
It has been widely believed for more than 70 years that auxin plays a central role in the induction of differential growth which causes gravitropic curvature. However, this long‐standing consensus about a role for auxin in gravitropism has only been achieved by allowing several mutually exclusive models to coexist. Furthermore, because there is no detailed model which is unchallenged by evidence, consensus is now centred on ill‐defined models which have a low predictive value, hence are harder to challenge experimentally. An increasing number of mutants with abnormal gravitropic behaviour are becoming available. Such mutants should be very helpful in challenging existing models of gravitropism and in providing new evidence on which to build improved, more precise models. However, to date, most studies of mutants with abnormal gravitropism have been guided, experimentally and conceptually, by the old inadequate and vague models. Consequently, the full potential of modern molecular analysis in aiding our understanding of gravitropism has yet to be realized.
Journal Article
New tricks for old dogmas?
[...]they still seem to believe that auxin movement across tropistically stimulated organs is relevant despite the fact that the two isolated halves of longitudinally bisected organs show a gravitropic response'. [...]our use of the model is appropriate. By contrast to maize, where the phototropic response resembles what is known for that of many other plants7, the phototropic response of Avena seems to be unique in several respects: it is the only plant in which a region of negative curvatures occur in the phototropic fluence response curve\"; the pattern of growth response is apparently more varied than in other plants2; and measurements of auxin concentrations in oat have given confusing and contradictory results'. [...]oat would seem a poor model system for phototropism.
Journal Article