Special areas of interest are:
Myelin provides a promising opportunity for an integrated account of an innovation at many biological levels, linking changes in the genome to changes in proteins expressed to changes in cellular, tissue and organ organization and finally to whole organism behavior and ecology. Although vertebrate myelin has been the focus of much research, most (but not all!) such studies lack an evolutionary perspective and they almost universally ignore the possibilities provided by invertebrate myelin. Viewed in the broad context of innovation, myelin may provide a useful tool for evolutionary biology. The Lenz-Hartline group has worked on several aspects of this broad picture, extending it to evolution of myelin in the malacostracan crustaceans:
Characterization, distribution, development, evolution and ecological significance of copepod myelin.
Phylogenetic origin and distribution of malacostracan myelin.
This project examined predator-prey interactions between larval clown fish and copepods. Much information about the ability of planktonic copepods (our primary research interest) to elude their numerous predators is being gained through studies of the neural responses of copepods to sensory stimuli and of the subsequent behavioral reactions. However, the acid test for our understanding of the copepod's side of this interaction is how well it applies in interactions with real predators. Among the many predators of marine are the various fishes that inhabit the worlds oceans, especially the larval stages of thiose fishes that are small enough to gain significant nutrition from individually-caught prey, yet large enough to capture and subdue them. To implement such a study, we cultured both copepods and fish in the lab so their interactions could be studied at 3D spatial resolutions in the sub-millimeter range and temporal resolutions in the sub-millisecond range. To do this, we collaborate with Dr. Rudi Strickler of the University of Wisconsin, Milwaukee and Dr. Ed Buskey, of the University of Texas' Marine Sciences Institute in Port Aransas.
The particular system we used for studies on network mechanisms, the
stomatogastric ganglion of decapod crustaceans, was also used
as a model for how nervous systems generate repetitive coordinated motor patterns, such as
those controlling walking, swimming, flying, breathing and heart beat in other animals.
Some years ago we found
special active cellular properties, that we termed "plateau potentials," which underlie
production of rhythmic stomatogastric motor activity. Plateau properties have since been
implicated in pattern production in a great variety of other organisms including mammals.
We examined the biophysical basis of these plateau potentials and on their modulatory regulation
by specific inputs from the central nervous system, as well as by hormones. In addition
(in a collaboration with Kathy Graubard at Univ. of Washington) we investigated
the role of spatial distribution of cellular mechanisms over branching neuritic trees and the
involvement of non-spike synaptic interactions in producing coordinated motor patterns.
Specific project areas included (click red-balls with links for more details):
Cellular properties that promote motor pattern generation,
Modulatory regulation of these properties,
"Non-spiking" synaptic interactions involved in motor pattern generation (collaboration with Dr. Katherine Graubard of the University of Washington).
Computational properties of cellular mechanisms distributed over branching dendritic trees (collaboration with Dr. Katherine Graubard of the University of Washington and Dr. Ann Castelfranco of PBRC)
Space-clamp errors in voltage clamp experiments on neurons with
attached processes: their nature and correctability (collaboration with Dr. Ann Castelfranco).
Lenz, P.H., D.K. Hartline and A.D. Davis (2000) "The need for speed. I. Fast reactions and myelinated axons in copepods" J. Comp. Physiol. 186: 337-345 PDF
Zalc, B. and D.R. Colman (2000) "Origins of vertebrate success" Science 288(5464) 271-272