Molecular genetic techniques

EARLY PHARMACOLOGICAL STUDIES AND THE IMPACT OF MOLECULAR GENETIC TECHNIQUES... 

The NMDA receptor has a heteromeric structure composed of two subunit types NRl and NR2, the latter having four subunits (NR2A-NR2D) (Fig. 10.2). Molecular genetic techniques have demonstrated that native NMDA receptors are likely to be composed of a combination of the NRl subunit (which can exist in eight different splice variants) and one or more of the four NR2 subunits which are the main determinants of functional diversity among the NMDA receptors (see Chapter 3 for further details). It has been shown that there are distinct developmental and spatial expression patterns of NMDA receptor NRl subunit splice variants and NR2 receptor subunits in the CNS. 

Since 1988, the methods that we use to isolate cDNAs of alkaloid biosynthesis have become ever more facile and sensitive, allowing for more efficient cDNA identification. We do not, however, yet understand enough about the cellular localization of alkaloid formation or about the nature of the catalysts to move completely away from enzymology and biochemistry and to use only molecular genetic techniques to dissect these biosynthetic pathways. Even our most recently successful cDNA isolations and identifications involved classical protein purification. We are beginning now to use proteomics and EST sequencing to identify natural product biosynthetic cDNAs, but these approaches are more feasible when a specialized cell/tissue type in which secondary metabolite biosynthetic pathways are active, can be isolated and used as a protein or RNA source. 

Molecular genetic techniques have confirmed the existence of multiple subtypes of p-adrenoceptors. Pi-Receptors and Pj-receptors have been cloned, and recent molecular biological evidence indicates the existence of at least one additional p-receptor sub-type, called the p3-receptor. It is suggested that the P3-receptor may mediate some of the metabolic effects of catecholamines, although no available p-blocker has been shown to rely on Pa-receptor antagonism for its therapeutic effectiveness. 

Mapping complex genomes has been invigorated by the development of rapid molecular genetic techniques. The presence of individual plant genes can now be... 

Identification of Echinococcus Isolates using Molecular Genetic Techniques.84... 

Although the basis of our current thinking on the mechanisms of action of oestro-gens has been with us for over 20 years, the molecular genetic techniques developed in the past decade have complemented more classical biochemical approaches... 

The advent of molecular genetic techniques such as amplified fragment length polymorphism (AFLP) analysis, where the degree of difference in the DNA between individual lines or species can be compared, has allowed the establishing of a much more precise assessment of genetic relatedness. 

All molecular genetic techniques require some amount of specialized scientific equipment. Because many items of equipment are expensive, it is a good idea to determine what instrumentation exists at the department or institution level, and to what extent it can be shared. Table II provides information on equipment required for the various comparative techniques and the ease with which each instrument can be shared. Items that typically are shared include large equipment such as high-speed and ultra-... 

Molecular genetic techniques now available hold great potential for improving strains for biological pesticide development. For example, low-virulence strains may be enhanced to improve efficacy. Species difficult to grow or that reproduce poorly in artificial culture may be genetically altered to make them available in large... 

To be sure, molecular genetics suffers from limitations. Many of its methods cannot be used without the availability of at least one known amino acid sequence. Thus, peptide isolation remains a critical need. Oligonucleotide probes can be too short, leading to useless or "false positive" hybridizations. Also, an appropriate bioassay is required to assess the authenticity of any product of molecular biology. However, the use of molecular genetic techniques will cause an explosion of information on insect neuropeptides and their sequences within the very near future. 

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