bacterium Bacillus thuringiensis shows. Over the past 10 years, scientists have found that this bug's insecticidal properties are encoded by a diverse array of genes that direct the synthesis of insecticidal proteins. These proteins act as selective poisons in the stomachs of insect larvae. Different genes produce poisons specific to various plant-attacking beetle larvae and caterpillars, as well as to the larvae of such carriers of human disease as mosquitoes and blackflies. By isolating and analyzing the genes involved, scientists can now "engineer" new gene combinations that improve on their naturally occurring counterparts, creating more potent weapons against a broader range of pests. Such engineering is an exquisite example of biocatalytic synthesis, using the bacterium's metabolic machinery to create proteins that would be prohibitively expensive to manufacture by industrial chemical processes. The new genes can be transferred to other bacterial hosts. Plants can also be "vaccinated" by endowing other organisms that grow in or on them with the gene. This scheme, which would provide a steady supply of the biopesticide to the plant, may prove more efficient than conventional spraying.

Those who protest the continued use of pesticides should be gladdened to know that there is hope for alternative products. Many are available now. Others will become available in the near future, if industry continues to support their development. For these new products to make their contribution, however, regulatory agencies and the public must be willing to agree that genetically engineered products are safe for use in the environment. The benefit to be derived from these products must be shown clearly to outweigh any perceived risk. This is the challenge to be faced if we are to continue to maintain and increase our agricultural productivity.

To produce high-octane components for gasoline, normal paraffins must be converted into branched paraffins, olefins, and aromatic compounds. Such transformations can be carried out over a platinum catalyst under a hydrogen atmosphere in a process called reforming. Extensive efforts have been undertaken to understand the fundamental chemistry involved in the reforming process. Vibrational spectroscopies, such as electron energy loss spectroscopy (EELS) and infrared spectroscopy, and 13C NMR spectroscopy have revealed that paraffins are only weakly adsorbed but undergo a loss of hydrogen on heating. The exact amount of hydrogen lost can be determined from temperature-programmed desorption spectroscopy, whereas the structure of the surface species formed as the temperature increases can be determined from both infrared and NMR spectroscopies. These techniques are particularly valuable because they can be used at el-



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