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Diagnosis of eutrophication requires evidence of disturbance to the balance of organisms. We describe a tool, the Plankton Community Integrity Index (PCII), derived from the Plankton Index (PI) for tracking change in the seasonal patterns of abundance of diatom and dinoflagellate lifeforms when plotted in state space. The tool uses a nutrient-minimum reference period to interpret PCII values as status indicators, with values close to 1 indicating “High” status and 0.6 a Biological Water Quality Criterion (BioWQC) target set at the “Fair”/“Good” status boundary. It has been applied to Hong Kong marine waters, using data from monthly samples from 1995 through 2021. A preliminary analysis, required for the PI method, confirmed monsoonal seasonality in the diatom lifeform. In 5 of the 9 water bodies examined, PCII time series correlated with those of Total Inorganic Nitrogen (TIN). Since 2020, all Water Control Zones met the operationally defined BioWQC target. © 2024 Elsevier Ltd

Heavy metals are serious environmental pollutants due to their toxicities and bioaccumulation effects. In this study, genes related to heavy metal responses in Chlamydomonas reinhardtii, a unicellular green algae model species with its entire genome sequenced, were characterized. Cadmium (Cd) is one of the major metal pollutants. Two mutant strains, Cds18 and CdrB2 with Cd sensitive and resistance respectively, were generated by insertational mutagensis in our laboratory previously. In mutant Cds18, CrMRP2 coding for an ABC transporter and in CdrB2, CrPMA2 coding for a P type ATPase were altered by the insertion. I performed a metal(loid)s resistance assay for both strains using the wild type strain C. reinhardtii 950 as control. Cds18 was sensitive to all the metal(loid)s studied, indicating the multi-metals responses of CrMRP2. CdrB2 showed responses to particular metals, in addition to Cd, the strain was resistance to Nickel (Ni) and Zinc (Zn) among the metal(loid)s tested. Expression of CrMRP2-GFP fusion protein in S. cerevisiae illustrated the vacuolar localization of gene products in yeast. The transcriptions of the two genes upon Cd, Ni and Zn stimulations were studied and related to the metal contents incorporated into wild type, Cds18 and CdrB2 cells. In wild type cells, CrMRP2 transcription can be induced by Cd, Ni and Zn. Wild type cells with CrMRP2 functioning has a higher ability to detoxify intracellular metal content. While the transcription of altered CrPMA2 is induced by Cd, Ni and Zn, metal contents in CdrB2 declined in late part of metal exposure. The information of this study contributed to the understanding of cellular detoxification mechanisms for heavy metals in photosynthetic organisms.

Heavy metals are serious environmental pollutants due to their toxicities and bioaccumulation effects. In this study, genes related to heavy metal responses in Chlamydomonas reinhardtii, a unicellular green algae model species with its entire genome sequenced, were characterized. Cadmium (Cd) is one of the major metal pollutants. Two mutant strains, Cds18 and CdrB2 with Cd sensitive and resistance respectively, were generated by insertational mutagensis in our laboratory previously. In mutant Cds18, CrMRP2 coding for an ABC transporter and in CdrB2, CrPMA2 coding for a P type ATPase were altered by the insertion. I performed a metal(loid)s resistance assay for both strains using the wild type strain C. reinhardtii 950 as control. Cds18 was sensitive to all the metal(loid)s studied, indicating the multi-metals responses of CrMRP2. CdrB2 showed responses to particular metals, in addition to Cd, the strain was resistance to Nickel (Ni) and Zinc (Zn) among the metal(loid)s tested. Expression of CrMRP2-GFP fusion protein in S. cerevisiae illustrated the vacuolar localization of gene products in yeast. The transcriptions of the two genes upon Cd, Ni and Zn stimulations were studied and related to the metal contents incorporated into wild type, Cds18 and CdrB2 cells. In wild type cells, CrMRP2 transcription can be induced by Cd, Ni and Zn. Wild type cells with CrMRP2 functioning has a higher ability to detoxify intracellular metal content. While the transcription of altered CrPMA2 is induced by Cd, Ni and Zn, metal contents in CdrB2 declined in late part of metal exposure. The information of this study contributed to the understanding of cellular detoxification mechanisms for heavy metals in photosynthetic organisms.

Heavy metals are serious environmental pollutants due to their toxicities and bioaccumulation effects. In this study, genes related to heavy metal responses in Chlamydomonas reinhardtii, a unicellular green algae model species with its entire genome sequenced, were characterized. Cadmium (Cd) is one of the major metal pollutants. Two mutant strains, Cds18 and CdrB2 with Cd sensitive and resistance respectively, were generated by insertational mutagensis in our laboratory previously. In mutant Cds18, CrMRP2 coding for an ABC transporter and in CdrB2, CrPMA2 coding for a P type ATPase were altered by the insertion. I performed a metal(loid)s resistance assay for both strains using the wild type strain C. reinhardtii 950 as control. Cds18 was sensitive to all the metal(loid)s studied, indicating the multi-metals responses of CrMRP2. CdrB2 showed responses to particular metals, in addition to Cd, the strain was resistance to Nickel (Ni) and Zinc (Zn) among the metal(loid)s tested. Expression of CrMRP2-GFP fusion protein in S. cerevisiae illustrated the vacuolar localization of gene products in yeast. The transcriptions of the two genes upon Cd, Ni and Zn stimulations were studied and related to the metal contents incorporated into wild type, Cds18 and CdrB2 cells. In wild type cells, CrMRP2 transcription can be induced by Cd, Ni and Zn. Wild type cells with CrMRP2 functioning has a higher ability to detoxify intracellular metal content. While the transcription of altered CrPMA2 is induced by Cd, Ni and Zn, metal contents in CdrB2 declined in late part of metal exposure. The information of this study contributed to the understanding of cellular detoxification mechanisms for heavy metals in photosynthetic organisms.