Distribution of carbon among photosynthetic end products in the bloom-forming arctic diatom Thalassiosira antarctica COMBER

Tillmann, Urban; Baumann, Marcus; Aletsee, L.

doi:10.1007/bf00238500

Cited by 10 publications

(6 citation statements)

References 32 publications

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“…Under sufficient nutrient supply the dominant pathway was the production of LMWMs, which are the precursors of macromolecules such as free amino acids and carbohydrates (Smith et al 1989, Tillmann et al 1989, Lindquist & Lignell 1997. Storage of free amino acids in diatom cells was already described by Conover (1975) and Dortch et al (1984), storage of carbohydrates by Antia et al (1963), Handa (1969), Haug & Myklestad (1976) and Lancelot & Mathot (1985).…”

Section: Discussionmentioning

confidence: 99%

“…Storage of free amino acids in diatom cells was already described by Conover (1975) and Dortch et al (1984), storage of carbohydrates by Antia et al (1963), Handa (1969), Haug & Myklestad (1976) and Lancelot & Mathot (1985). The determination of carbohydrates as metabolites or within the polysaccharide fraction depends on the structure, grade of polymerisation, and solubility of these substances (Hitchcock 1983, Tillmann et al 1989.…”

Section: Discussionmentioning

confidence: 99%

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Changes in photosynthetic carbon allocation in algal assemblages of Arctic sea ice with decreasing nutrient concentrations and irradiance

Möck¹,

Gradinger²

2000

Mar. Ecol. Prog. Ser.

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Photosynthetic carbon assimilation into protein, low-molecular-weight metabolites (LMWM), polysaccharides, total lipids and into 3 lipid classes (neutral lipids, glycolipids and phospholipids) was determined in batch-culture experiments with natural assemblages of Arctic-ice algae under simulated in situ irradiance. Photosynthate allocation in 3 parallel batch incubations revealed a high contribution of lipid assimilation to total particulate carbon production (54.6 ± 0.4%) followed by LMWM (35.0 ± 1.0%), carbohydrates (7.3 ± 0.1%) and proteins (3.0 ± 0.8%). Total lipids were mainly composed of glycolipids (67.4 ± 3.5%) with a relatively lower allocation into phospholipids (28.1 ± 6.7%) and neutral lipids (4.5 ± 3.2%). Nutrient addition (final concentrations: Si(OH)4 = 65.5 ± 0.4 µmol l-1, NO3 = 42.9 ± 0.6 µmol l-1, PO4 = 2.6 ± 0.0 µmol l-1) caused algal community growth of 0.22 ± 0.0 d-1 until nutrients became limiting 10 d later. Si(OH)4:NO3 ratios and NO3:PO4 ratios in the cultures decreased from initially 1.5 ± 0.0 to 0.2 ± 0.1 and 16.8 ± 0.2 to 1.2 ± 0.5, respectively. During the first few days of incubation, relative proportions of carbon production for proteins increased 3-fold (max. 11.1 ± 1.0%), those for LMWM 1.5-fold (max. 45.7 ± 6.4%), whereas lipids decreased (min. 32.0 ± 0.4%). Increasing relative proportions of carbon production for carbohydrates were only observed at the end of exponential growth (max. 12.9 ± 1.3%). A dramatic increase of lipids was measured under nutrient depletion (max. 70.9 ± 3.6%) after Day 10, which was the result of glycolipid production, while protein and carbohydrate production decreased to values below 5% of total particulate carbon production. LMWM also attained lower incorporation rates under nutrient depletion (min. 23.5 ± 1.1%). Production of glycolipids during exponential algal growth is attributed to an acclimation to decreasing irradiance as a consequence of an increase in algal biomass. Decreasing particulate carbon:chlorophyll a ratios during the experiment indicate a physiological response to a reduction in irradiance with simultanous glycolipid production. Glycolipids are the main lipid class in chloroplasts, and especially in thylakoidmembranes, which are strongly developed during low-light acclimation. Excess light energy during stationary algal growth after Day 10 is dissipated in the form of glycolipids and/or neutral lipids. But the latter are probably more significant under high-light conditions

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Changes in photosynthetic carbon allocation in algal assemblages of Arctic sea ice with decreasing nutrient concentrations and irradiance

Möck¹,

Gradinger²

2000

Mar. Ecol. Prog. Ser.

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“…Obviously only those diatom species can probably persist in Antarctic sea ice, which are cold adapted and able to regulate photosynthesis efficiently under simultaneous light and N-limitation. Ecophysiological investigations based on both limitations are still rare for sea ice diatoms and have been either conducted with natural communities or with single species (Tillmann et al, 1989;Kirst and Wiencke, 1995;Taguchi and Smith, 1997;McMinn et al, 1999). Our approach studies the mechanisms of photosynthesis regulation in diatom species, which coexist in the natural sea ice community (Fragilariopsis curta, Navicula gelida var.…”

Section: Introductionmentioning

confidence: 99%

Photosynthetic energy conversion under extreme conditions—I: important role of lipids as structural modulators and energy sink under N-limited growth in Antarctic sea ice diatoms

2002

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The availability of dissolved nutrients such as nitrate under extreme low temperatures is a strong determinant in the development and growth of ice diatoms. Consequently we investigated regulation of photosynthesis in a mixed culture of three diatom species, which grew in chemostats at À1 C, 15 mmol photons m À2 s À1 under N-limitation. When nitrogen is limiting, pigment-protein complexes are one of the most affected structures under low-light conditions. The loss of integral polar thylakoid components destabilized the bilayer structure of the membrane with consequences for lipid composition and the degree of fatty acid desaturation. N-Limitation caused a decrease in monogalactosydiacylglycerol (MGDG) and a simultaneous increase in bilayer forming digalactosyldiacylglycerol (DGDG). Their ratio MGDG:DGDG decreased from 3.4AE 0.1 to 1.1 AE 0.4, while 20:5 n-3 fatty acids of chloroplast related phospholipid classes such as phosphatidylglycerol (PG) increased under N-limitation. These data reveal that lipids are important components, required to sustain membrane structure under a deficiency of integral membrane bound proteins and pigments. Nonetheless, energy conversion at photosystem II is still affected by N-limitation despite this structural regulation. Photosynthetic quantum yield (F v /F m ) and electron transport rates decreased under N-limitation caused by an increasing amount of electron acceptors (second stable electron acceptor=Q B ) which had slower reoxidation kinetics. The energy surplus under these conditions is stored in triacylglycerols, the main energy sink in Antarctic sea ice diatoms under N-limitation. #

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“…Under nonlimiting growth conditions, lipids for example make up only a small percentage (10%) of macromolecular dry weight of Phaeodactylum tricornutum cells, with less than 50% of it being found in TAGs (Remmers et al 2018). This is supported by the results of Gleitz and Thomas (1993), Thomas and Gleitz (1993), Palmisano et al (1988) and Tillmann et al (1989), who showed that in polar diatoms (both in the field and in cultures), the relative amount of photosynthetically assimilated carbon invested into lipids is between 5% and 20% when temperature is at or below 0°C. In contrast, lowmolecular-weight metabolites (primarily free amino acids and monosaccharides) are almost systematically the compartment in which carbon is most invested, sometimes accounting for more than 50% of total fixed carbon.…”

Section: Fragilariopsis Cylindrus Survival In Darknessmentioning

confidence: 70%

The possible fates of Fragilariopsis cylindrus (polar diatom) cells exposed to prolonged darkness

Sciandra

Forget

Bruyant

et al. 2022

Journal of Phycology

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At high latitudes, the polar night poses a great challenge to photosynthetic organisms that must survive up to six months without light. Numerous studies have already shed light on the physiological changes involved in the acclimation of microalgae to prolonged darkness and subsequent re‐illumination. However, these studies have never considered inter‐individual variability because they have mainly been conducted with bulk measurements. On the other hand, such long periods are likely to impact within‐population selection processes. In this study, we hypothesized that distinct subpopulations with specific traits may emerge during acclimation of a population of diatoms to darkness. We addressed this hypothesis using flow cytometry (FCM), which allow to individually characterize large numbers of cells. The ecologically dominant polar pennate diatom Fragilariopsis cylindrus was subjected to three dark acclimation (DA) experiments of one, three, and five months duration, during which all cultures showed signs of recovery once light became available again. Our results suggest that darkness survival of F. cylindrus relies on reduction of metabolic activity and consumption of carbon reserves. In addition, FCM allowed us to record three different causes of death, each shared by significant numbers of individuals. The first rendered cells were unable to survive the stress caused by the return to light, probably due to a lack of sufficient photoprotective defenses. The other two were observed in two subpopulations of cells whose physiological state deviated from the original population. The data suggest that starvation and failure to maintain dormancy were the cause of cell mortality in these two subpopulations.

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Distribution of carbon among photosynthetic end products in the bloom-forming arctic diatom Thalassiosira antarctica COMBER

Cited by 10 publications

References 32 publications

Changes in photosynthetic carbon allocation in algal assemblages of Arctic sea ice with decreasing nutrient concentrations and irradiance

Changes in photosynthetic carbon allocation in algal assemblages of Arctic sea ice with decreasing nutrient concentrations and irradiance

Photosynthetic energy conversion under extreme conditions—I: important role of lipids as structural modulators and energy sink under N-limited growth in Antarctic sea ice diatoms

The possible fates of Fragilariopsis cylindrus (polar diatom) cells exposed to prolonged darkness

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