1
|
Smith WO, Trimborn S. Phaeocystis: A Global Enigma. ANNUAL REVIEW OF MARINE SCIENCE 2024; 16:417-441. [PMID: 37647611 DOI: 10.1146/annurev-marine-022223-025031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
The genus Phaeocystis is globally distributed, with blooms commonly occurring on continental shelves. This unusual phytoplankter has two major morphologies: solitary cells and cells embedded in a gelatinous matrix. Only colonies form blooms. Their large size (commonly 2 mm but up to 3 cm) and mucilaginous envelope allow the colonies to escape predation, but data are inconsistent as to whether colonies are grazed. Cultured Phaeocystis can also inhibit the growth of co-occurring phytoplankton or the feeding of potential grazers. Colonies and solitary cells use nitrate as a nitrogen source, although solitary cells can also grow on ammonium. Phaeocystis colonies might be a major contributor to carbon flux to depth, but in most cases, colonies are rapidly remineralized in the upper 300 m. The occurrence of large Phaeocystis blooms is often associated with environments with low and highly variable light and high nitrate levels, with Phaeocystis antarctica blooms being linked additionally to high iron availability. Emerging results indicate that different clones of Phaeocystis have substantial genetic plasticity, which may explain its appearance in a variety of environments. Given the evidence of Phaeocystis appearing in new systems, this trend will likely continue in the near future.
Collapse
Affiliation(s)
- Walker O Smith
- Department of Biological Sciences, Virginia Institute of Marine Science, William & Mary, Gloucester Point, Virginia, USA;
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Scarlett Trimborn
- Division of Biosciences, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany;
| |
Collapse
|
2
|
Nitrogen and Iron Availability Drive Metabolic Remodeling and Natural Selection of Diverse Phytoplankton during Experimental Upwelling. mSystems 2022; 7:e0072922. [PMID: 36036504 PMCID: PMC9599627 DOI: 10.1128/msystems.00729-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Nearly half of carbon fixation and primary production originates from marine phytoplankton, and much of it occurs in episodic blooms in upwelling regimes. Here, we simulated blooms limited by nitrogen and iron by incubating Monterey Bay surface waters with subnutricline waters and inorganic nutrients and measured the whole-community transcriptomic response during mid- and late-bloom conditions. Cell counts revealed that centric and pennate diatoms (largely Pseudo-nitzschia and Chaetoceros spp.) were the major blooming taxa, but dinoflagellates, prasinophytes, and prymnesiophytes also increased. Viral mRNA significantly increased in late bloom and likely played a role in the bloom's demise. We observed conserved shifts in the genetic similarity of phytoplankton populations to cultivated strains, indicating adaptive population-level changes in community composition. Additionally, the density of single nucleotide variants (SNVs) declined in late-bloom samples for most taxa, indicating a loss of intraspecific diversity as a result of competition and a selective sweep of adaptive alleles. We noted differences between mid- and late-bloom metabolism and differential regulation of light-harvesting complexes (LHCs) under nutrient stress. While most LHCs are diminished under nutrient stress, we showed that diverse taxa upregulated specialized, energy-dissipating LHCs in low iron. We also suggest the relative expression of NRT2 compared to the expression of GSII as a marker of cellular nitrogen status and the relative expression of iron starvation-induced protein genes (ISIP1, ISIP2, and ISIP3) compared to the expression of the thiamine biosynthesis gene (thiC) as a marker of iron status in natural diatom communities. IMPORTANCE Iron and nitrogen are the nutrients that most commonly limit phytoplankton growth in the world's oceans. The utilization of these resources by phytoplankton sets the biomass available to marine systems and is of particular interest in high-nutrient, low-chlorophyll (HNLC) coastal fisheries. Previous research has described the biogeography of phytoplankton in HNLC regions and the transcriptional responses of representative taxa to nutrient limitation. However, the differential transcriptional responses of whole phytoplankton communities to iron and nitrogen limitation has not been previously described, nor has the selective pressure that these competitive bloom environments exert on major players. In addition to describing changes in the physiology of diverse phytoplankton, we suggest practical indicators of cellular nitrogen and iron status for future monitoring.
Collapse
|
3
|
Koppelle S, López-Escardó D, Brussaard CPD, Huisman J, Philippart CJM, Massana R, Wilken S. Mixotrophy in the bloom-forming genus Phaeocystis and other haptophytes. HARMFUL ALGAE 2022; 117:102292. [PMID: 35944956 DOI: 10.1016/j.hal.2022.102292] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/11/2022] [Accepted: 07/13/2022] [Indexed: 05/13/2023]
Abstract
Phaeocystis is a globally widespread marine phytoplankton genus, best known for its colony-forming species that can form large blooms and odorous foam during bloom decline. In the North Sea, Phaeocystis globosa typically becomes abundant towards the end of the spring bloom, when nutrients are depleted and the share of mixotrophic protists increases. Although mixotrophy is widespread across the eukaryotic tree of life and is also found amongst haptophytes, a mixotrophic nutrition has not yet been demonstrated in Phaeocystis. Here, we sampled two consecutive Phaeocystis globosa spring blooms in the coastal North Sea. In both years, bacterial cells were observed inside 0.6 - 2% of P. globosa cells using double CARD-FISH hybridizations in combination with laser scanning confocal microscopy. Incubation experiments manipulating light and nutrient availability showed a trend towards higher occurrence of intracellular bacteria under P-deplete conditions. Based on counts of bacteria inside P. globosa cells in combination with theoretical values of prey digestion times, maximum ingestion rates of up to 0.08 bacteria cell-1 h-1 were estimated. In addition, a gene-based predictive model was applied to the transcriptome assemblies of seven Phaeocystis strains and 24 other haptophytes to assess their trophic mode. This model predicted a phago-mixotrophic feeding strategy in several (but not all) strains of P. globosa, P. antarctica and other haptophytes that were previously assumed to be autotrophic. The observation of bacterial cells inside P. globosa and the gene-based model predictions strongly suggest that the phago-mixotrophic feeding strategy is widespread among members of the Phaeocystis genus and other haptophytes, and might contribute to their remarkable success to form nuisance blooms under nutrient-limiting conditions.
Collapse
Affiliation(s)
- Sebastiaan Koppelle
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94920, 1090 XH, Amsterdam, The Netherlands.
| | - David López-Escardó
- Ecology of Marine Microbes, Institut de Ciènces del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Catalonia, Spain
| | - Corina P D Brussaard
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94920, 1090 XH, Amsterdam, The Netherlands; Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg, Texel, The Netherlands
| | - Jef Huisman
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94920, 1090 XH, Amsterdam, The Netherlands
| | - Catharina J M Philippart
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg, Texel, The Netherlands; Department of Physical Geography, Utrecht University, P.O. Box 80115, 3508 TC, Utrecht, The Netherlands
| | - Ramon Massana
- Ecology of Marine Microbes, Institut de Ciènces del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Catalonia, Spain
| | - Susanne Wilken
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94920, 1090 XH, Amsterdam, The Netherlands.
| |
Collapse
|
4
|
Castell C, Rodríguez-Lumbreras LA, Hervás M, Fernández-Recio J, Navarro JA. New Insights into the Evolution of the Electron Transfer from Cytochrome f to Photosystem I in the Green and Red Branches of Photosynthetic Eukaryotes. PLANT & CELL PHYSIOLOGY 2021; 62:1082-1093. [PMID: 33772595 PMCID: PMC8557733 DOI: 10.1093/pcp/pcab044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/15/2021] [Indexed: 05/11/2023]
Abstract
In cyanobacteria and most green algae of the eukaryotic green lineage, the copper-protein plastocyanin (Pc) alternatively replaces the heme-protein cytochrome c6 (Cc6) as the soluble electron carrier from cytochrome f (Cf) to photosystem I (PSI). The functional and structural equivalence of 'green' Pc and Cc6 has been well established, representing an example of convergent evolution of two unrelated proteins. However, plants only produce Pc, despite having evolved from green algae. On the other hand, Cc6 is the only soluble donor available in most species of the red lineage of photosynthetic organisms, which includes, among others, red algae and diatoms. Interestingly, Pc genes have been identified in oceanic diatoms, probably acquired by horizontal gene transfer from green algae. However, the mechanisms that regulate the expression of a functional Pc in diatoms are still unclear. In the green eukaryotic lineage, the transfer of electrons from Cf to PSI has been characterized in depth. The conclusion is that in the green lineage, this process involves strong electrostatic interactions between partners, which ensure a high affinity and an efficient electron transfer (ET) at the cost of limiting the turnover of the process. In the red lineage, recent kinetic and structural modeling data suggest a different strategy, based on weaker electrostatic interactions between partners, with lower affinity and less efficient ET, but favoring instead the protein exchange and the turnover of the process. Finally, in diatoms the interaction of the acquired green-type Pc with both Cf and PSI may not yet be optimized.
Collapse
Affiliation(s)
- Carmen Castell
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, cicCartuja, Sevilla, Spain
| | - Luis A Rodríguez-Lumbreras
- Instituto de Ciencias de la Vid y del Vino (ICVV), CSIC—Universidad de La Rioja—Gobierno de La Rioja, Logroño, Spain
| | - Manuel Hervás
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC and Universidad de Sevilla, cicCartuja, Sevilla, Spain
| | - Juan Fernández-Recio
- Instituto de Ciencias de la Vid y del Vino (ICVV), CSIC—Universidad de La Rioja—Gobierno de La Rioja, Logroño, Spain
| | | |
Collapse
|
5
|
Castell C, Bernal-Bayard P, Ortega JM, Roncel M, Hervás M, Navarro JA. The heterologous expression of a plastocyanin in the diatom Phaeodactylum tricornutum improves cell growth under iron-deficient conditions. PHYSIOLOGIA PLANTARUM 2021; 171:277-290. [PMID: 33247466 DOI: 10.1111/ppl.13290] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
We have investigated if the heterologous expression of a functional green alga plastocyanin in the diatom Phaeodactylum tricornutum can improve photosynthetic activity and cell growth. Previous in vitro assays showed that a single-mutant of the plastocyanin from the green algae Chlamydomonas reinhardtii is effective in reducing P. tricornutum photosystem I. In this study, in vivo assays with P. tricornutum strains expressing this plastocyanin indicate that even the relatively low intracellular concentrations of holo-plastocyanin detected (≈4 μM) are enough to promote an increased growth (up to 60%) under iron-deficient conditions as compared with the WT strain, measured as higher cell densities, content in pigments and active photosystem I, global photosynthetic rates per cell, and even cell volume. In addition, the presence of plastocyanin as an additional photosynthetic electron carrier seems to decrease the over-reduction of the plastoquinone pool. Consequently, it promotes an improvement in the maximum quantum yield of both photosystem II and I, together with a decrease in the acceptor side photoinhibition of photosystem II-also associated to a reduced oxidative stress-a decrease in the peroxidation of membrane lipids in the choroplast, and a lower degree of limitation on the donor side of photosystem I. Thus the heterologous plastocyanin appears to act as a functional electron carrier, alternative to the native cytochrome c6 , under iron-limiting conditions.
Collapse
Affiliation(s)
- Carmen Castell
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla and CSIC, Seville, Spain
| | - Pilar Bernal-Bayard
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla and CSIC, Seville, Spain
| | - José M Ortega
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla and CSIC, Seville, Spain
| | - Mercedes Roncel
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla and CSIC, Seville, Spain
| | - Manuel Hervás
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla and CSIC, Seville, Spain
| | - José A Navarro
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla and CSIC, Seville, Spain
| |
Collapse
|