Laboratory-based studies of mutation frequencies and 

 distributions will be a useful starting point for understanding the 

 effect of environmental factors on the rates of genetic change. In 

 conjunction with phenotypic analyses, assays of molecular variants, 

 such as restriction fragment length polymorphism (RFLP) analysis 

 and/or PCR random amplified polymorphic DUA(RAPO) (Williams et al. , 

 1990), will be critical. PCR is sensitive enough to detect single 

 point mutations from crude nucleic acid extracts, and analyses are 

 reasonably rapid. A future challenge will be the assessment of 

 natural mutation rates, and how environmental stress might 

 influence these rates. These studies will necessarily be linked to 

 an understanding of the extent and role of intraspecies 

 variability. Identification of model populations will be important 

 for the study of mutational frequency amongst natural populations. 



Molecular Probes for Organic Function 



Environmental perturbation may profoundly affect the 

 functional roles and interactions between co-occurring species. In 

 some communities, particularly microhabitats, functional 

 interactions are still poorly understood. Microbes do not exist as 

 individuals in the environment, but interact as closely linked, 

 interdependent communities. In some instances, undue stress on one 

 member of a microbial consortium may have a profound effect on the 

 entire community structure and function. In other cases, 

 functional redundancy among different members may buffer 

 environmental stress. Molecular analyses of population structure, 

 such as those described above, have the potential to detect 

 covariance between species, and species interdependence. In 

 addition, molecular probes applied at the in situ level may provide 

 information on the spatial relationships and interactions between 

 species. 



The significance of molecular approaches for studying the 

 functions of organisms, and factors which limit function, are 

 described below. The use of molecular probes to assay and detect 

 functional gene and mRNA sequences present in key proteins, linked 

 to species and group-specific molecular probes, may allow 

 correlation of species to function with in situ assays, so allowing 

 simultaneous dissection of communities for both species composition 

 and functional redundancy. Differential expression of related 

 genes in different species could also be detected. 



III-7 



