Flagella and cilia of eukaryotic cells are based on the axoneme, an internal arrangement of nine doublets and a central pair of microtubules. This highly conserved structure is widely utilized for producing movement in both plants and animals. The goal of this project is to understand how elements of the flagellar axoneme interact to produce the flagellar beat. Bull, rat and mouse sperm will be used to study flagellar beating and axonemal function. Experiments to observe and compare microtubule activation in all three species will be performed on sperm flagella treated (by one of four previously developed methods) to permit disintegration by microtubule sliding. The extent and rate of microtubule sliding will independently be determined in actively swimming, detergent- extracted sperm models by videotape recording and computer-assisted analysis of the flagellar motion. Agents with known effects on flagellar motility, such as nickel, calcium or cadmium ions, vanadate, and cyclic AMP, will be tested for their selective effects on microtubule sliding in both disintegrating and intact (motile) flagella. Additionally, genetically dysfunctional mouse sperm will be examined for abnormalities in axonemal function. Sperm from M. domesticus carrying two different haplotypes of the T-complex, and sperm from M. domesticus carrying one haplotype plus DNA from M. spretus at the homologous T locus will be examined, to attempt to link specific axonemal functions to genetic loci. %%% Flagella are slender extensions of the cell which "beat", i.e., wave back and forth in a specific and characteristic way. They represent a highly conserved mechanism for either propelling a cell through its environment or moving the environment in the vicinity of the cell. Examples of such motility include the swimming of sperm in the uterus or of protozoans in ponds, the movement of mucus and inhaled particles in the trachea and bronchi of the lungs, and the intake of food particles by protozoans. Flagella consist of highly ordered arrays of microtubules, termed axonemes, which run the full length of the cilium or flagellum. Other microtubule-associated proteins, notably dynein, are involved in the transduction of biochemical energy (ATP) to mechanical energy (movement). The axonemal beat is the result of certain of the microtubules sliding longitudinally past others, within the membrane-bound constraints of the flagellum, resulting in a bending of the organelle. The goal of this project is to understand how the microtubular elements of the axoneme interact to produce the flagellar beat. The Principal Investigator has developed several unique experimental methods to examine various aspects of these interactions, which will be further exploited in the course of the work. The experimental results, together with a computer simulation of flagellar beating which has been developed by the Principal Investigator, will lead to a working model of axonemal function. This work could have significant impact on the development of novel materials based on biological models.
