11:20 AM - 12:00 PM

<aside> <img src="/icons/map-pin_green.svg" alt="/icons/map-pin_green.svg" width="40px" /> DPB Seminar Room + Zoom (DGE Conference Room, Solarium, DGE Lobby, Library)

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<aside> <img src="/icons/megaphone_green.svg" alt="/icons/megaphone_green.svg" width="40px" /> Chair by: Jose Avila Peltroche

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<aside> <img src="/icons/music-artist_green.svg" alt="/icons/music-artist_green.svg" width="40px" /> Establishing a genetic platform for studying photodevelopment in macrophytic brown algae

Frej Tulin, José Avila Peltroche, Andrey Malkovskiy, Dimitri Tolleter, Frej Tulin, Arthur Grossman

8:45 AM - 9:25 AM

Brown macroalgae are multicellular marine photosynthetic organisms, many of which are key habitat-forming species in coastal ecosystems. Many species are also used as low-input aquaculture crops for production of food and other bio-products. However, the potential of brown algae for industrial applications is limited by a fundamental lack in knowledge about the regulation of key biological processes such as photosynthesis, morphogenesis and sexual reproduction. Many examples of regulation by light intensity and quality have been described, but the molecular/genetic basis remains unknown. We fill this knowledge gap by studying how light signaling couples photophysiology and development in the small and powerful brown algal model Ectocarpus. We found that Ectocarpus has underdeveloped chloroplasts and grows extremely slowly under red light. Exposure to weak blue light (2 µmol photons m-2 s-1) causes a rapid increase in many chloroplast-targeted genes, including plastid DNA polymerases and components of the plastid protein translocation machinery. Stepwise increases in blue light intensity showed that reproductive development requires at least 10x more blue light than vegetative growth, suggesting that distinct photoreceptor genes are involved. We are currently using targeted gene editing of photoreceptor genes and unbiased genetic screens to elucidate the underlying light signaling pathways. Blue light is a primary cue in the aquatic environment. Our work establishes a platform for studying how blue light interacts with other signals, and with endogenous genetic programs to control the growth and development in the brown algae.

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<aside> <img src="/icons/music-artist_green.svg" alt="/icons/music-artist_green.svg" width="40px" /> 2D and 3D image analysis applications for single cells and whole plants

Andrey Malkovskiy - Carnegie Science

8:45 AM - 9:25 AM

The past two decades saw a vast expansion of fluorescent probes, as well as the availability of high-resolution imaging for macroscopic (whole plant, organism) and subcellular imaging of slow (growth, development) and fast dynamic processes (relocation and reorganization, synthesis and degradation). The visualization of such processes is among techniques that provide more conclusive evidence of underlying biological phenomena, commonly phrased as “a picture is worth a thousand words”. However, qualitative assessment of images can only go that far. Robust quantitative approaches not only allow better statistical evaluation of observed phenomena, but also allow to elucidate the finest differences between them. I will be presenting some custom algorithms for advanced 2D and 3D image analysis and segmentation for collaborative studies with Stanford and Carnegie scientists, which resulted in multiple published studies. The most recent 3D ellipsoid approximation of cell shapes and geometric segmentation approach allowed to observe redistribution of mitochondria in Chlamydomonas reinhardtii with very high accuracy and reproducibility for high- resolution confocal images.

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