Research Biologist

Welcome to the Latz Laboratory

We are a marine biology laboratory at Scripps Institution of Oceanography specializing in bioluminescence, with two goals:

  • UNDERSTAND how marine organisms interact with their environment
  • DISSEMINATE our knowledge to the scientific and public communities

Recent Publications

Latz, MI, Rohr J.  2013.  Bathyphotometer bioluminescence potential measurements: A framework for characterizing flow agitators and predicting flow-stimulated bioluminescence intensity. Continental Shelf Research. 61–62:71-84. AbstractWebsite

Bathyphotometer measurements of bioluminescence are used as a proxy for the abundance of luminescent organisms for studying population dynamics; the interaction of luminescent organisms with physical, chemical, and biological oceanographic processes; and spatial complexity especially in coastal areas. However, the usefulness of bioluminescence measurements has been limited by the inability to compare results from different bathyphotometer designs, or even the same bathyphotometer operating at different volume flow rates. The primary objective of this study was to compare measurements of stimulated bioluminescence of four species of cultured dinoflagellates, the most common source of bioluminescence in coastal waters, using two different bathyphotometer flow agitators as a function of bathyphotometer volume flow rate and dinoflagellate concentration. For both the NOSC and BIOLITE flow agitators and each species of dinoflagellate tested, there was a critical volume flow rate, above which average bioluminescence intensity, designated as bathyphotometer bioluminescence potential (BBP), remained relatively constant and scaled directly with dinoflagellate cell concentration. At supra-critical volume flow rates, the ratio of BIOLITE to NOSC BBP was nearly constant for the same species studied, but varied between species. The spatial pattern and residence time of flash trajectories within the NOSC flow agitator indicated the presence of dominant secondary recirculating flows, where most of the bioluminescence was detected. A secondary objective (appearing in the Appendix) was to study the feasibility of using NOSC BBP to scale flow-stimulated bioluminescence intensity across similar flow fields, where the contributing composition of luminescent species remained the same. Fully developed turbulent pipe flow was chosen because it is hydrodynamically well characterized. Average bioluminescence intensity in a 2.54-cm i.d. pipe was highly correlated with wall shear stress and BBP. This correlation, when further scaled by pipe diameter, effectively predicted bioluminescence intensity in fully developed turbulent flow in a 0.83-cm i.d. pipe. Determining similar correlations between other bathyphotometer flow agitators and flow fields will allow bioluminescence potential measurements to become a more powerful tool for the oceanographic community.

Jin, K, Klima JC, Deane G, Dale Stokes M, Latz MI.  2013.  Pharmacological investigation of the bioluminescence signaling pathway of the dinoflagellate Lingulodinium polyedrum: evidence for the role of stretch-activated ion channels. Journal of Phycology. 49:733-745. AbstractWebsite

Dinoflagellate bioluminescence serves as a whole-cell reporter of mechanical stress, which activates a signaling pathway that appears to involve the opening of voltage-sensitive ion channels and release of calcium from intracellular stores. However, little else is known about the initial signaling events that facilitate the transduction of mechanical stimuli. In the present study using the red tide dinoflagellate Lingulodinium polyedrum (Stein) Dodge, two forms of dinoflagellate bioluminescence, mechanically stimulated and spontaneous flashes, were used as reporter systems to pharmacological treatments that targeted various predicted signaling events at the plasma membrane level of the signaling pathway. Pretreatment with 200 μM Gadolinium III (Gd3+), a nonspecific blocker of stretch-activated and some voltage-gated ion channels, resulted in strong inhibition of both forms of bioluminescence. Pretreatment with 50 μM nifedipine, an inhibitor of L-type voltage-gated Ca2+ channels that inhibits mechanically stimulated bioluminescence, did not inhibit spontaneous bioluminescence. Treatment with 1 mM benzyl alcohol, a membrane fluidizer, was very effective in stimulating bioluminescence. Benzyl alcohol-stimulated bioluminescence was inhibited by Gd3+ but not by nifedipine, suggesting that its role is through stretch activation via a change in plasma membrane fluidity. These results are consistent with the presence of stretch-activated and voltage-gated ion channels in the bioluminescence mechanotransduction signaling pathway, with spontaneous flashing associated with a stretch-activated component at the plasma membrane.

Maldonado, EM, Latz MI.  2011.  Species-specific effects of fluid shear on grazing by sea urchin larvae: comparison of experimental results with encounter-model predictions. Marine Ecology-Progress Series. 436:119-130. AbstractWebsite

Small-scale turbulence can alter the rate of plankton predator-prey encounters. Encounter models predict that prey ingestion by slow-swimming zooplankton is enhanced at low levels of turbulence. We investigated whether small-scale turbulence increases ingestion for the slow-swimming, suspension-feeding pluteus larvae of the white urchin Lytechinus pictus and the purple urchin Strongylocentrotus purpuratus. Model predictions of the critical level of turbulence, epsilon(cr), above which encounters due to turbulence are greater than those due to behavior (swimming or suspension feeding) alone, were experimentally tested using short-and long-term grazing treatments. Because urchin larvae are smaller than the smallest eddy scales of turbulence and thus experience turbulence as laminar shear, larvae were exposed to flow conditions using a simple laminar shear flow with dissipation rates, epsilon, of 0, 0.1, 0.4, and 1 cm(2) s(-3). Short-term ingestion of beads by L. pictus larvae was unaffected by epsilon < 1 cm(2) s(-3) but was 30% greater at this level, which was greater than ecr based on flow speeds produced in suspension feeding. Long-term flow treatments with algal prey had no significant effect on grazing or growth. Short-term ingestion of beads by S. purpuratus larvae was unaffected by epsilon < epsilon(cr) based on suspension feeding; the effect of long-term flow exposure on ingestion and growth could not be investigated because of high mortality, suggesting greater sensitivity to flow exposure compared to L. pictus. Experimental results are consistent with model predictions that ecr is high, and thus levels of turbulence in the ocean are not expected to significantly increase ingestion and reduce food limitation in suspension-feeding urchin larvae.