Stephen M. Rich

Associate Professor of Plant, Soil, and Insect Sciences, University of Massachusetts

S. Rich Plant, Soil, and Insect Sciences Web Site
S. Rich Lab Web Site

Ph.D.: University of California, Irvine
Postdoctoral Training: University of Rochester

Molecular Genetics, Genomics and Population Biology of Animal Infectious Diseases

Research in the Rich lab focuses on the evolutionary dynamics of pathogen and host populations. We are particularly interested in the processes that have altered the genes and genomes of these organisms in a way that has facilitated their continued interaction. Some parasite-host associations date far back in the geologic record, indicating a finely tuned balance in the antagonism of their shared evolution. The genetic novelties that permit rapid, somatic generation of a near-infinite ensemble of immunoglobulin diversity, are testament to such a history. Coincident with these events are the innovations in genomes of parasites, which have provided these organisms with adaptive mechanisms for avoiding the hypervariable immune response of their hosts. My research aims are to discern the importance of various factors—such as natural selection, horizontal exchange of genetic material, population structure, development of novel gene functions and differential expression—in shaping past and present host-parasite interactions. By determining the extent of genetic variation among populations of these organisms, it becomes possible to make strong inferences about the mechanisms that, (a) generate variation, and (b) serve to maintain high level of variation and its concomitant, adaptive-potentiality.

The rapid, recent influx of modern molecular biology techniques coupled with our ever-increasing theoretical knowledge of molecular evolution, make it now possible to determine the short-and long-term evolutionary histories of human parasites and associated diseases. My research incorporates these various tools in research programs encompassing two distinct human pathogen systems: (1) Plasmodium falciparum, the mosquito-borne, protozoan agent of malignant malaria, and (2) Borrelia spp., the tickborne spirochetes of Lyme disease and relapsing fever. Both systems are fascinating models for studying complex interactions of pathogen-vector-host coevolution and for determining the means by which their genomes are shaped by these interactions.

Representative publications:

Rich, S.M. (2006) Distribution and abundance of polymorphism in the malaria genome. in Selective Sweep (D. Nurminsky, Ed.). Landes Bioscience, 121 pp.

Rich, S.M. and F.J. Ayala (2006) Evolutionary origins of human malaria parasites. in Malaria: Genetic and Evolutionary Aspects (K.R. Dronamraju and P. Arese, Eds.). Springer, 190 pp.

Rich, S.M. (2004) The unpredictable past of Plasmodium vivax revealed in its genome. Proc. Natl. Acad. Sci. USA 101: 15547-15548.

Rich, S.M. (2004) Selective sweeps and genome evolution in the malaria parasite. in Selective Sweeps (D. Nurminsky, ed.) in press.

Rich, S.M. and F.J. Ayala. (2004) Evolution and population structure of parasitic protozoa: the Plasmodium model. In Evolution: from Molecules to Ecosystems (A. Moya and E. Font, eds.) Oxford University Press, pp. 82-93.

Rich, S.M. and F.J. Ayala. (2004) Evolution of Human Malaria. in Infectious Disease and Host parasite evolution, (Dronamraju, ed.) Cambridge University Press.

Gov Y., I. Borovok, M. Korem, V.K. Singh, R.K. Jayaswal, B.J. Wilkinson, S.M. Rich, and N. Balaban (2004) Quorum sensing in staphylococci is regulated via phosphorylation of three conserved histidine residues. J. Biol. Chem. 279:14665-14672

Rich, S.M. and F.J. Ayala (2004) Evolutionary history of human malaria and its causative agents. Advances Parasitol. 54:256-280 .

Tumwine J.K., Kekitiinwa A, Nabukeera N, Akiyoshi DE, Rich SM, Widmer G, Feng X, Tzipori S. (2003) Cryptosporidium parvum in children with diarrhea in Mulago Hospital, Uganda. Am. J Trop Medi Hyg 68 710-715

Ferreira M.U., W.L. Ribeiro, A.P. Tonon, F. Kawamoto, S.M. Rich (2003) Sequence diversity and evolution of the malaria vaccine candidate merozoite surface protein-1 (MSP-1) of Plasmodium falciparum. Gene 304: 65-75.

Rich, S.M. and F.J. Ayala (2002) Evolution of Human Malaria. in Encyclopedia of Evolution, (Pagel, ed.) Oxford University Press. pp. 645-649.

Feng, X., S. M. Rich, S. Tzipori, and G. Widmer (2002) Experimental evidence for genetic recombination in the opportunistic pathogen Cryptosporidium parvum. Mol. Biochem. Parasitol, 119:55-62.

Mukherjee J., K. Chios, D. Fishwild, D. Hudson, S. O'Donnell, S.M., Rich, A., Donohue-Rolfe, S. Tzipori. (2002) Human Stx2-specific monoclonal antibodies prevent systemic complications of Escherichia coli O157:H7 infection. Infect. Immun., 70:612-619.

Mukherjee J, K. Chios, D. Fishwild, D. Hudson, S. O'Donnell, S.M., Rich, A., Donohue-Rolfe, and S. Tzipori. (2002) Production and Characterization of Protective Human Antibodies against Shiga Toxin 1. Infect. Immun., 70:5896-5899.

Okhuysen P.C., S.M. Rich SM, C.L. Chappell CL, K.A. Grimes, G. Widmer, X. Feng, and S. Tzipori. (2002) Infectivity of a Cryptosporidium parvum isolate of cervine origin for healthy adults and interferon-gamma knockout mice. J. Infect. Dis., 185:1320-1325.

Rich, S.M., S.A. Sawyer, and A.G.Barbour. (2001) Antigen polymorphism in Borrelia hermsii, a clonal pathogenic bacterium. Proc. Natl. Acad. Sci. USA, 98: 15038-15043.

Burke, W.D., H. Malik, S.M. Rich, and T.H. Eickbush. (2001) Ancient lineages of non-LTR retrotransposons in the primitive eukaryote, Giardia lamblia. Mol. Biol. Evol. 19:619-630.