PUPCYCLE Day 10 – Game of IRON!

Sunday, June 02, 2019 – Collecting and Prepping Narrow Shelf Samples for Incubation #2

PUPCYCLE Log: Day 10 – Game of IRON!

A few short hours after completing the filtering and storing

Figure 21 – Maite and Jian’s diatoms have quite the view during their incubation period. [Image credit: Miriam Sutton]
of all the samples from Incubation Site #1: Broad Shelf, the researchers prepared their stations for the samples from Incubation Site #2. Seawater samples from Incubation Site #2: Narrow Shelf began arriving on deck shortly before midnight. Each research group secured their samples in the storage containers and placed them in the incubation systems strapped to the aft deck of the R/V Oceanus. Some of the scientists returned to their bunks around 3:00AM while others worked through mid-morning until the Deep Water Pumping System had completed its service to PUPCYCLE 2019 and was once again secured on deck.

The incubation system shown in Figure 21 is set up for experiments being conducted by Maite Maldonado and Jian Guo, both from the University of British Columbia (UBC). Their research focuses on iron transfer, or uptake, by diatoms. They are interested in determining if diatoms have the ability to take up iron from a certain compound, known as DFB (desferroxamine B). DFB is a type of siderophore (“iron carrying”) compound that binds tightly to iron found in seawater, thereby making the iron unavailable to other microorganisms. While some bacteria (prokaryotic – containing no nucleus) may have the ability to produce another type of siderophore that can access the iron, it is unclear whether eukaryotic algae (containing a nucleus), such as diatoms, have this same capability. Iron is vital to phytoplankton’s growth and survival and their research will provide insights into how much energy, if any, the diatoms are willing to expend in their effort to secure the iron they need.


Figure 22 – Maite and Jian’s diatoms have quite the view during their incubation period. [Image credit: Maite Maldonado (UBC)]
Researchers have learned that some species of diatoms are more adapted to low-nutrient environments while other species are more adapted to high-nutrient environments. When there is sufficient iron in their marine environment, both species are less interested in acquiring iron. Scientists describe this lack of motivation as “low affinity.” When iron is limited, diatoms have less iron in their cells and their affinity increases as they become desperate for any form of iron that might be available to them. As noted in Matt’s research earlier (Day 09: Saturday, June 01: Micrometers, Nanometers, Picometers, Oh My!), iron can be found attached to other organisms and particles found in seawater besides DFB (i.e., chlorophyll, bacteria, ligands). Jian and Maite are investigating to see if diatoms living in an iron-limited environment might have the ability to take up the DFB compound and extract the iron for their cellular processes, which include photosynthesis. They, like many of the other PUPCYCLE 2019 researchers, will freeze and store their samples for transcriptomics back at UBC. The genes expressed by the diatoms will identify whether they are exerting energy to gain access to the iron bound to the DFB.


Jian Guo was born in China and immigrated to Canada to pursue her PhD at the University of British Columbia. She moved to California to complete her post-doctoral studies at the Monterey Bay Aquarium Research Institute (MBARI) before returning to the University of British Columbia, where she is completing a post-doctorate focusing on trace metal contaminants being released in the ocean by wastewater plants in Vancouver.

Today’s Certificate Challenge: In which type of environment (Fe-limited or Fe-available) do diatoms possess the highest affinity for gathering iron?