School of Science Division of Life Science 41 Calcareous Dinoflagellates Supervisor: WONG Joseph Tin Yum / LIFS Student: KIM Dongwook / BIOT Course: UROP 1100, Spring Calcareous dinoflagellates are a type of biomineralising phytoplankton that is responsible for marine metal accumulation. One example of calcareous dinoflagellates, Thoracosphaera heimii, has been promptly observed under a growth medium treated with oxalic acid. The retarded regeneration of biomineral, reduced growth rate, and stressed granulation suggest that oxalic acid has cytotoxic effects due to membrane damage, calcium ion depletion, and oxygen depletion. Calcareous Dinoflagellates Supervisor: WONG Joseph Tin Yum / LIFS Student: LIN Wong Yan / BIOT Course: UROP 1000, Summer This progress project focus on cultivation of the marine calcareous dinoflagellates Crypthecodinium cohnii (C. cohnii), for its resistance to artemisinin, a drug known for its anti-malarial properties, and have been widely used in malaria treatment. From screening C. cohnii with artemisinin resistance, this project aims to understanding C. cohnii responses to chemical stressors. C. cohnii culture are spread on MLH agar plate supplemented with artemisinin and the incubate at 28°C in the dark to assess cell viability. Future work will involve testing with varying artemisinin concentration to identify C. cohnii favoring conditions and investigated underlying mechanism. In order to explore potential resistance mechanism in calcareous dinoflagellates may have both ecological and commercial application. Carbon 6x Minus through Increase Production of DMSP Supervisor: WONG Joseph Tin Yum / LIFS Student: LEE Sum Yeung Sunny / BCB Course: UROP 1100, Fall Playing significant roles in marine ecosystems, the biosynthesis of DMSP involves methylation, transamination, and decarboxylation and a uniquely observed order in Crypthecodinium cohnii. After several intermediates has been suggested, a methionine decarboxylase (MetDC) has been purified from C. cohnii, although its sequence does not align with known proteins, leading to uncertainties regarding its function. Comparative studies reveal that C. cohnii MetDC shares some common features with that from other species, such as Streptomyces and Dryopteris and with enzymes from other DMSP synthesis pathway. This review highlights the unique aspects of MetDC in C. cohnii and its implications for understanding DMSP biosynthesis across different organisms.
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