Faculty

Diana Johnson
Associate Professor of Biology
Lisner Hall 330
Office: (202) 994-7121
Fax: (202) 994-6100
E-Mail: dejohnsn@gwu.edu

Courses

• BiSc 107 - Genetics
• BiSc 108 - Genetics Laboratory
• BiSc 175 - Independent Study in Genetics and Evolutionary Biology
• BiSc 227 - Seminar in Genetics
• BiSc 228 - Population Genetics

Education

B.S., Biology, Cornell College, NY, 1970
Ph.D., Biology, University of Chicago, IL, 1975

Research

In recent years my research interests have focused on gene function in Drosophila. The publication of the genome sequence of Drosophila melanogaster has allowed the identification of gene families and has simplified the processes needed to identify the sequences of genes with detectable phenotypic effects.

Early in my career I studied genetic variation in populatons. I was particularly interested in differentiation associated with speciation. More recently I have returned to the area of population diversity. My lab has been involved in general studies of genetic variation including mtDNA variation in man.

In the last year my lab has been involved in molecular mapping of genes responsible for visibly mutant phenotypes in Drosophila. We have a particular interest in the genes that relate to eye color as this is an opportunity to study in detail the types of genes involved in producing a morphological character. Eye color in Drosophila is a complex trait influenced by genes of many different types. The Drosophila eye has two classes of pigments contained in it, ommochromes and pteridines. Many of the genes involved in synthesis of these pigments have already been identified. However, eye color does not depend solely on the synthesis of the pigments. It has been demonstrated that three genes involved in producing ABC transporters, white, brown, and scarlet are involved in the transport of pigment precursors to the eye.

Eye pigments are located in pigment granules which are modified lysosomal structures. Several laboratories have identified the molecular sequences of genes involved in lysosomal transport which were first identified because the mutant alleles affected eye color in Drosophila.

The molecular sequences of a number of eye color mutations are not known. This lab is currently attempting to identify the sequences of several mutations. We hope to make predictions about their function once the sequence is identified and compared to other known sequences.

We are currently investigating a small gene family in Drosophila. We are characterizing gene expression patterns for the members of the family with respect to development. We are also studying the evolutionary relationships between members of the family. Finally we are characterizing specific activities of one of the genes.