Screening Hypothesis

Any scientific hypothesis is simply an attempt to provide a theoretical framework that allows people to understand the processes that interest them and also enables 

Is biological activity a rare property for a molecule to possess  

Maybe the effects of individual chemicals is enhanced in the presence of other chemicals—the magic mixture argument  

There are other such scenarios that can be proposed. Evidence exists for both additive and synergistic actions. There is nothing magical about mixtures. The effects of mixtures can be explained in terms of the actions of the individual chemicals, all of which obey the usual physicochemical laws.3° 

So how do these arguments apply to the evolution of NPs Suppose that one chemical with rather weak biomolecular activity exists in an individual, but that activity will only become evident if another type of biomolecular activity is evolved. The probability of the first chemical possessing any form of biomolecular activity would be low. However, the chance of the combined activity becoming evident is the same as the chance of the second chemical possessing its form of biomolecular activity because one needs that 

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As expected from electrostatic screening hypothesis, the addition of NaCl has an increasing effect on the stability (see Figure 8). Moreover, while c increases with c, in pure water, the reverse is observed at 20g/l of NaCl. 

The Screening Hypothesis seeks to explain the evolution of NPs when the chances of any one NP benefiting the producer are indeed very low. This simple hypothesis predicts that certain metabolic traits which favour the generation and retention of NP diversity will be retained during the evolution of NP metabolism. The most important of these predicted metabolic traits is the ability of enzymes making NPs to either accept... 

Some criticisms of the Screening Hypothesis helped refine the model and the thinking behind the model has since been applied to a wider range of metabolism (see Chapter 9). 

Building a new model to explain NP diversity—the Screening Hypothesis... 

The implications of the Law of Mass Action to the evolution of NPs—the Screening Hypothesis... 

Fourth, and finally, Rausser and Small seem to have assumed, like so many scientists until recendy, that organisms have evolved only to retain biologically active NPs, as if organisms were doing the hrst stage of a screening trial on behalf of humans. As explained in Chapter 5, the Screening Hypothesis, based on well-established physicochemical principles, postulates that most NPs are simply members of the NP library that the natural world has made. Like individual chemicals in the libraries of synthetic chemicals made by humans, most of the chemicals will possess no potent biomolecular activity. 

The evolutionary constraint that lies at the heart of the Screening Hypothesis (that any molecule has a low probability of possessing potent biomolecular activity—see Chapter 5 for detailed arguments) must have influenced the evolution of inducibility. The reasoning behind this statement requires a recap of some principles. 

How might an understanding of the Screening Hypothesis inform attempts to manipulate NP composition ... 

Thus the Screening Hypothesis predicts that the manipulation of the NP composition of plants will produce unknown outcomes but there is only a low probability of harm to human consumers. However, will the public be reassured by what in effect is a probability argument I would suggest that there is a high probability that they will not. 

Unfortunately, unknown to the authors of the Screening Hypothesis to explain NP diversity, the term Screening Hypothesis was used by educationalists to postulate that education acted as a filter to screen those that can be trained. That version of the terminology currently wins a Google search. 

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