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Latz Laboratory Research Interests

General interests on the bioengineering, biomechanics, and sensory biology of marine organisms include the following specific areas:

• Flow sensitivity of phytoplankton

• Mechanosensory signal transduction in dinoflagellates

• Physiological ecology of midwater animals

• Bioluminescence as a monitor of physiological stress

• The ecology of bioluminescence in the ocean

Present research activities:

• Effect of flow on marine plankton
  All plankton experience a dynamic fluid environment due to the effects of wind, waves, tides, and currents. In some cases, flow can alter physiological processes. We focus on dinoflagellates, some of the most flow-sensitive organisms known.
  • Effect of flow on population growth
    There is growing evidence that small-scale turbulence affects the population growth of some dinoflagellates by inhibiting cell division. Laboratory experiments are investigating how shear sensitivity in dinoflagellates is affected by growth conditions, and how cell cycle progression is altered when population growth is inhibited.

  • Effect of flow on cell morphology
    In the dinoflagellate, Ceratocorys horrida, water motion comparable to that from surface wind and wave action causes a remarkable transformation in cell morphology. Normally long-spined cells become short-spined and reduced in size, population growth is inhibited, and the swimming ability of cells is reduced. This change is completely reversible upon the return to calm conditions. The changes in morphology and swimming may allow cells to sink away from turbulent surface conditions that may inhibit population growth and potentially damage cells.

  • Effect of flow on bioluminescence
    Higher levels of flow than those that cause the inhibition of population growth or morphology change stimulate flashing in luminescent dinoflagellate species. Ongoing work using a variety of hydrodynamically defined flow conditions are oinvestigating the properties of fluid motion that are stimulatory to cells.

  • Flow sensing -- transduction and intracellular signaling
    How do phytoplankton sense and respond to flow stimuli; specifically, how does a mechanical stimulus result in a chemical signal within the cell? Dinoflagellates, the most shear-sensitive marine organisms, are used as a model system for investigating the cellular processes involved in mechanosensory transduction and intracellular signaling.

  • Luminescent flow visualization
    Bioluminescent dinoflagellates can be used as flow markers which turn on only when suitable levels of fluid shear are present. This approach is useful for visualizing complex or undefined flow fields not amenable to conventional flow visualization techniques, such as those around a swimming dolphin, or in commercial bioreactors.

• Effect of heavy metals on metazoans
  A new project is investigating the accumulation of heavy metals by ophiuroids (brittlestars), and its physiological toxicity as monitored by changes in bioluminescence. Field experiments using transplanted animals from clean to polluted sites, and vice versa, will determined the time course of bioaccumulation and its reversal, respectively.

• Camouflage behavior in midwater animals
  Many mesopelagic animals rely on environmental light cues for regulating behaviors such as swimming and bioluminescence. For example, the midwater shrimp, Sergestes similis, responds to light with dim bioluminescence which countershades the body to camouflage it from predators. Recent studies have investigated the link between behavioral and visual sensitivity, while future work will explore how camouflage behavior is controlled through the interaction of physiological pathways.

The Lab has an opening for a graduate student for Fall 2000. If you are interested in the effect of flow on plankton (e.g., signal transduction, gene activity, physiology and behavior), please contact Dr. Latz.

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