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Research interests:

Individual amoeboid cells of the cellular slime molds eat bacteria and aggregate to form multicellular organisms. They can do these tasks effectively because of their sensitivity to different chemicals produced by bacteria and by themselves. The response of the amoebae to these chemicals is chemotaxis. an orienting of their motion towards the source of these attractants. Thus, the amoebae can hunt for their food and, later, find each other for aggregation.

The problem is: How does a cell that is only 1/100th of a millimeter in diameter determine that there is more of a substance on one side of itself than elsewhere; i.e., how can it tell from what direction the substance is coming? We have shown that these slime mold amoebae will generate many very long filamentous pseudopodia in the presence of these attractants. These "filopodia" are involved in amoeboid motion and effectively increase the surface area without changing the real volume of the cell. We are studying the cellular responses to chemicals that are similar to the attractants, but do not affect motion. Various combinations that lead to either inhibition or stimulation of chemotaxis also have a parallel effect on the filopodial array. This may provide clues to the distribution and types of receptors.
 
Selected Publications:
 
Rifkin JL, Goldberg RR. (2006). Effects of chemoattractant pteridines upon speed of D. discoideum vegetative amoebae. Cell Motil Cytoskeleton. 63(1):1-5.

Rifkin, J.L. (2002). Quantitative analysis of the behavior of Dictyostelium discoideum amoebae: stringency of pteridine reception. Cell Motil. & Cytoskeleton. 51(1): 39-48.

Rifkin, J.L. (2001). Folate reception by vegetative Dictyostelium discoideum amoebae: distribution of receptors and trafficking of ligand. Cell Motil. & Cytoskeleton. 48:121-129.

Rifkin, J.L. and Wali, A.W. (1986). Effects of pteridines on the filopodia of Dictyosteliun discoideum vegetative amoebae. Cell Motility and the Cytoskeleton 6:479-484.

Rifkin, J.L. and Isik, F. (1984).Effects of folic acid upon filopodia of Dictyostelium discoideum vegetative amoebae. Cell. Motil. 4:129-135.

Rifkin, J.L. and Speisman, R.A.(1976). Filamentous extensions of vegetative amoebae of the cellular slime mold, Dictyostelium. Trans. Amer. Micros. Sec. 95:165-173.
 
 
List of Publications from PubMed