Genetics of murine leishmaniasis.

Leishmaniasis encompasses a number of disease syndromes, caused by several species of the digenetic protozoan Leishmania, and is transmitted by sandflies. The mouse model of the disease has been used to identify genes involved in disease susceptibility--for example, the Slc11a1 gene, important in resistance to Leishmania donovani--and to map loci important in Leishmania major infection. The genetics of the host response to L. major has been shown to be complex and to involve much more than the T helper cell response.     

Genetics of colon cancer.

Strikingly rapid advances in the identification of genetic events that are important in colonic carcinogenesis have been made in the past several years. Specific inherited (adenomatous polyposis coli gene) and acquired (ras gene point mutations; c-myc gene amplification; allelic deletion at specific sites on chromosomes 5, 17, and 18) genetic abnormalities appear to be capable of mediating steps in the progression from normal to malignant colonic mucosa. Understanding these genetic factors and how they influence cellular function will have a profound effect on medical practice. High-risk populations will be (and are being) identified by genetic markers, thus allowing prevention and screening to be more precisely targeted to the population at risk; intervention strategies will be designed on the basis of the known cellular defects of neoplastic colonic mucosa; and new molecular preventive and therapeutic approaches can be developed.     

Genetics of Candida albicans.

Candida albicans is among the most common fungal pathogens. Infections caused by C. albicans and other Candida species can be life threatening in individuals with impaired immune function. Genetic analysis of C. albicans pathogenesis is complicated by the diploid nature of the species and the absence of a known sexual cycle. Through a combination of parasexual techniques and molecular approaches, an effective genetic system has been developed. The close relationship of C. albicans to the more extensively studied Saccharomyces cerevisiae has been of great utility in the isolation of Candida genes and development of the C. albicans DNA transformation system. Molecular methods have been used for clarification of taxonomic relationships and more precise epidemiologic investigations. Analysis of the physical and genetic maps of C. albicans and the closely related Candida stellatoidea has provided much information on the highly fluid nature of the Candida genome. The genetic system is seeing increased application to biological questions such as drug resistance, virulence determinants, and the phenomenon of phenotypic variation. Although most molecular analysis to data has been with C. albicans, the same methodologies are proving highly effective with other Candida species.