Biology Department

Contact Info
tonzetch@bucknell.edu  

Educational Background
M.A., Duke University
Ph.D., Duke University

Recent Activities
Genetics and biochemical structure of Drosophila polytene chromosome. Conservation of heterochromatin; structure of centromere and telomere DNA. I teach courses in general genetics,introductory genetics and evolution and a nonmajors course in human genetics. I am also the premed advisor and am the primary faculty resource for students intersested in the health professions.

Research interest
Research interests are directed towards the genetic and biochemical structure of the polytene chromosomes of Drosophila. Earlier investigations have centered on the pattern of chromosomal inversion polymorphisms in several species of Drosophila and the nature of break points in chromosomes generating inversions. Recent studies in the lab have focused on the overall conservatism of linkage groups among species of Drosophila as reflected by the arrangement of selected genes, determined by the technique of in situ hybridization. We are also interested in the nature and positioning of heterochromatin, especially that form of heterochromatin located at the centromere and telomere. Both of these locations on chromosomes are characterized by DNA of unique properties. The DNA is usually highly reiterated, late in replicating during the cell cycle and packaged in a different manner producing visible structural differentiation in some cases. In order to isolate fragments of DNA from these regions we have cloned a library of genomic fragments from Drosophila hydei. Through in situ hybridization we identified several clones from the centromeric region.

Selected publications
Daniel, D. L., Jr., J. Tonzetich, M. I. Chernin, J. H. McMaster and J. F. Novak. 1994. Acquisition of resistance to 6-azauridine through DNA amplification in neoplastic but not normal osteoblasts. Anticancer Research 14:937-942.

Carson, H. L., J. Tonzetich, and L. T. Doescher. 1992. Polytene chromosome maps for Hawaiian Drosophila. Chapter 8 in Drosophila Inverstion Polymorphism, ed. C. B. Krimhas and J. R. Powell. CRC Press.

Tonzetich, J., S. Hayashi, and T. A. Grigliatti. 1990. Conservatism of sites of tRNA loci among the linkage groups of several Drosophila species. J. Molec. Evolution. 30:182-188

 
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