APL-UW Home

Jobs
About
Campus Map
Contact
Privacy
Intranet

Monica Orellana

Research Scientist/Engineer - Principal & Principal Oceanographer

Email

morellan@apl.uw.edu

Phone

206-685-5422

Department Affiliation

Polar Science Center

Education

B.S. Biology, Concepcion (Chile), 1980

M.S. Biological Oceanography, University of Washington, 1985

Ph. D. Biological Oceanography, University of Washington, 1990

Publications

2000-present and while at APL-UW

Temporal and metabolic overlap between lipid accumulation and programmed cell death due to nitrogen starvation in the unicellular chlorophyte Chlamydomonas reinhardtii

Sathe, S., M.V. Orellana, N.S. Baliga, and P.M. Durand, "Temporal and metabolic overlap between lipid accumulation and programmed cell death due to nitrogen starvation in the unicellular chlorophyte Chlamydomonas reinhardtii," Phycol. Res., 67, 173-183, doi:10.1111/pre.12368, 2019.

More Info

1 Jul 2019

Lipid accumulation due to nitrogen depletion has been studied extensively in Chlamydomonas reinhardtii and the metabolic changes that lead to triacylglycerol biosynthesis have been of particular interest to researchers in the biodiesel industry. The induction of programmed cell death (PCD) in response to nitrogen starvation has also been documented in related chlorophytes. Here, we examined the temporal and metabolic overlap of lipid accumulation and PCD in response to nitrogen starvation in the important model organism C. reinhardtii. Nitrogen starvation induced physiological stress, measured by the progressive decline in chlorophyll a fluorescence, reduced photosynthetic efficiency and decreased growth. In keeping with previous reports, cells accumulated lipids reaching a peak after 2–3 days. At the same time, DNA nicking and caspase‐like protease activity was observed in a proportion of cells, and ultrastructural observations confirmed that death was via PCD. Our results demonstrate that DNA nicking and caspase‐like activity are observed during PCD in C. reinhardtii in response to nitrogen starvation, and that death occurs at the same time as lipid biosynthesis. Microalgal lipid production due to nitrogen depletion in C. reinhardtii is limited by the decrease in culture growth and knowing that the loss of culture density is, at least in part, due to PCD is important for the biotechnology industry.

Physical and optical characteristics of heavily melted 'rotten' Arctic sea ice

Frantz, C.M., B. Light, S.M. Farley, S. Carpenter, R. Lieblappen, Z. Courville, M.V. Orellana, and K. Junge, "Physical and optical characteristics of heavily melted 'rotten' Arctic sea ice," Cryosphere, 13, 775-793, doi:10.5194/tc-13-775-2019, 2019.

More Info

5 Mar 2019

Field investigations of the properties of heavily melted "rotten" Arctic sea ice were carried out on shorefast and drifting ice off the coast of Utqiagvik (formerly Barrow), Alaska, during the melt season. While no formal criteria exist to qualify when ice becomes rotten, the objective of this study was to sample melting ice at the point at which its structural and optical properties are sufficiently advanced beyond the peak of the summer season. Baseline data on the physical (temperature, salinity, density, microstructure) and optical (light scattering) properties of shorefast ice were recorded in May and June 2015. In July of both 2015 and 2017, small boats were used to access drifting rotten ice within ~32 km of Utqiagvik. Measurements showed that pore space increased as ice temperature increased (–8 to 0°C), ice salinity decreased (10 to 0 ppt), and bulk density decreased (0.9 to 0.6 g cm-3). Changes in pore space were characterized with thin-section microphotography and X-ray micro-computed tomography in the laboratory. These analyses yielded changes in average brine inclusion number density (which decreased from 32 to 0.01 mm-3), mean pore size (which increased from 80 μm to 3 mm), and total porosity (increased from 0% to > 45%) and structural anisotropy (variable, with values of generally less than 0.7). Additionally, light-scattering coefficients of the ice increased from approximately 0.06 to > 0.35 cm-1 as the ice melt progressed. Together, these findings indicate that the properties of Arctic sea ice at the end of melt season are significantly distinct from those of often-studied summertime ice. If such rotten ice were to become more prevalent in a warmer Arctic with longer melt seasons, this could have implications for the exchange of fluid and heat at the ocean surface.

Ocean acidification conditions increase resilience of marine diatoms

Valenzuela, J.J., A.L.G. de Lomana, A. Lee, E.V. Armbrust, M.V. Orellana, and N.S. Baliga, "Ocean acidification conditions increase resilience of marine diatoms," Nature Comm., 9, 2328, doi:10.1038/s41467-018-04742-3, 2018.

More Info

13 Jun 2018

The fate of diatoms in future acidified oceans could have dramatic implications on marine ecosystems, because they account for ~40% of marine primary production. Here, we quantify resilience of Thalassiosira pseudonana in mid-20th century (300 ppm CO2) and future (1000 ppm CO2) conditions that cause ocean acidification, using a stress test that probes its ability to recover from incrementally higher amount of low-dose ultraviolet A (UVA) and B (UVB) radiation and re-initiate growth in day–night cycles, limited by nitrogen. While all cultures eventually collapse, those growing at 300 ppm CO2 succumb sooner. The underlying mechanism for collapse appears to be a system failure resulting from "loss of relational resilience," that is, inability to adopt physiological states matched to N-availability and phase of the diurnal cycle. Importantly, under elevated CO2 conditions diatoms sustain relational resilience over a longer timeframe, demonstrating increased resilience to future acidified ocean conditions. This stress test framework can be extended to evaluate and predict how various climate change associated stressors may impact microbial community resilience.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
Close

 

Close