Behavioural versus physiological photoprotection in epipelic and epipsammic benthic diatoms

Blommaert, Lander; Lavaud, Johann; Vyverman, Wim; Sabbe, Koen

doi:10.1080/09670262.2017.1397197

Cited by 29 publications

(38 citation statements)

References 46 publications

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“…The use of coupled Chl a fluorescence with imaging techniques has proven to be of paramount interest to monitor the temporal changes in MPB biomass, in particular with an Imaging-PAM fluorometer (Du et al, 2010;Vieira et al, 2013;Blommaert et al, 2018). Imaging of Chl a fluorescence allows assessment of the dynamics of the "photosynthetically active (or productive) biomass" (PAB) at the surface of sediment (Herlory et al, 2005;Guarini et al, 2008).…”

Section: Monitoring Of the Changes In The Mpb Pab At The Surface Of Smentioning

confidence: 99%

“…two ways of avoiding this drawback: (1) instead of measuring F t , to use the red and near-infrared LEDs of the Imaging-PAM LED panel to measure an NDVI index shown to be well correlated with Chl a sediment content (Blommaert et al, 2018); (2) to replace the blue Imaging-PAM measuring head by the red (650-660 nm) one for measuring F t , which most likely (see section "Influence of the Light Spectrum on the Amount of PAB Present at the Surface of Sediment: Specific Effect of BL Wavelengths") will not trigger MPB migration at night. These minor technical limitations being considered, our experimental setup allowed us to reliably monitor MPB migration dynamics ex situ.…”

Section: Monitoring Of the Changes In The Mpb Pab At The Surface Of Smentioning

confidence: 99%

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The Vertical Migratory Rhythm of Intertidal Microphytobenthos in Sediment Depends on the Light Photoperiod, Intensity, and Spectrum: Evidence for a Positive Effect of Blue Wavelengths

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Barnett et al. Intertidal Microphytobenthos Light-Dependent Rhythmic Migration MPB surface accumulation, as compared to other wavelengths (white, green, and red) in patterns that were intensity-dependent and species-dependent. In particular, we found two species, Navicula spartinetensis and Gyrosigma fasciola, which strongly migrate up under blue light and could potentially be used as model species for further studying the light-responses of intertidal MPB.

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Section: Monitoring Of the Changes In The Mpb Pab At The Surface Of Smentioning

confidence: 99%

Section: Monitoring Of the Changes In The Mpb Pab At The Surface Of Smentioning

confidence: 99%

The Vertical Migratory Rhythm of Intertidal Microphytobenthos in Sediment Depends on the Light Photoperiod, Intensity, and Spectrum: Evidence for a Positive Effect of Blue Wavelengths

et al. 2020

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“…The circadian rhythms are endogenously controlled and are kept for several days in laboratory conditions without artificial tides and exposed to continuous light (Round and Happey, 1965;Paterson, 1986;Serôdio et al, 1997;Mitbavkar and Anil, 2004;Coelho et al, 2011). The smaller photo-regulation movements are one of the main photo-regulation mechanisms of epipelic diatoms (Jesus et al, 2009;Perkins et al, 2010;Cartaxana et al, 2011;Laviale et al, 2016), while epipsammic diatoms (strongly associated to sediment grains) depend mainly on the thermal dissipation of excessive light energy through the xanthophyll cycle (XC) to photo-regulate (Cartaxana et al, 2011;Barnett et al, 2015;Blommaert et al, 2018). The XC relies on the presence of a transthylakoidal proton gradient to deepoxidise diadinoxanthin (Diad) into its energy-dissipation form diatoxanthin (Diat).…”

Section: Introductionmentioning

confidence: 99%

“…Overall, published data shows that microphytobenthos depend on both photo-regulation mechanisms but that the two strategies are strongly dependent on their life forms (i.e., epipelic vs. epipsamic) (Cartaxana et al, 2011;Barnett et al, 2015). A few studies have investigated the trade-off between vertical migration (VM) and NPQ (Perkins et al, 2010;Serôdio et al, 2012;Barnett et al, 2015;Laviale et al, 2016;Blommaert et al, 2018). Diatoms movements have been differentiated in phototaxis and photokinesis (Nultsch, 1971;Häder, 1986).…”

Section: Introductionmentioning

confidence: 99%

Effect of Light Intensity and Light Quality on Diatom Behavioral and Physiological Photoprotection

et al. 2020

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In this study, we investigated the different photoregulation responses of diatom dominated natural biofilms to different light intensities and wavelengths, over a tidal cycle in the laboratory. We compared the overall effect of light spectral quality from its light absorption (Qphar) dependent effect. Two different conditions were compared to study photoprotective strategies: sediment (migrational) and without sediment (non-migrational). Three different colors (blue, green, and red) and two light intensities (low light, LL at 210 µmol.photons.m −2 .s −1 and high light, HL at 800 µmol.photons.m −2 .s −1) showed strong interactions in inducing behavioral and physiological photoprotection. Non-migrational biofilm non-photochemical quenching (NPQ) was much more reactive to blue HL than red HL while it did not differ in LL. We observed a biphasic NPQ response with a light threshold between 200 and 250 µmol.photons.m −2 .s −1 of Qphar that elicited the onset of physiological photoprotection. Similar HL differences were not observed in migrational biofilms due to active vertical migration movements that compensated light saturating effects. Our results showed that within migrational biofilms there was an interaction between light quality and light intensity on cell accumulation pattern at the sediment surface. This interaction led to inverse diatom accumulation patterns between blue and red light at the same intensity: LL (blue + 200.67%, red + 123.96%), HL (blue + 109.15%, red + 150.34%). These differences were largely related to the differential amount of light absorbed at different wavelengths and highlighted the importance of using wavelength standardized intensities. Different vertical migration patterns significantly affected the total pigment content measured at the surface, suggesting that cell could migrate downward more than 2 mm as a photoregulatory response. Colloidal carbohydrates patterns paralleled the vertical migration movements, highlighting their possible role in diatom motility. Our data strongly suggests a wavelength and Qphar dependent light stress threshold that triggers upward and downward movements to position microphytobenthic diatoms at their optimal depth.

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“…However, P. tricornutum only possesses four LHCX genes, and these still enable the species to rapidly adjust to a highly fluctuating light climate (Lepetit et al, 2017). In addition, the ability of motile epipelic diatoms to rapidly migrate away from strong light conditions could minimize the need for strong physiological photoprotection (Serôdio et al, 2001;Barnett et al, 2015;Laviale et al, 2016;Blommaert et al, 2018) and hence also the need for so many functional genes in S. robusta. Lastly, the presence of many LHCX genes may allow FIGURE 4 | Amino-acid alignment of regions 1 and 2 of Chlamydomonas reinhardtii CrLHCSR3, P. tricornutum LHCX1-4, T. pseudonana LHCX6, and all LHCX sequences of S. robusta.…”

Section: Discussionmentioning

confidence: 99%

Light Regulation of LHCX Genes in the Benthic Diatom Seminavis robusta

et al. 2020

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Intertidal benthic diatoms experience a highly variable light regime, which especially challenges these organisms to cope with excess light energy during low tide. Nonphotochemical quenching of chlorophyll fluorescence (NPQ) is one of the most rapid mechanisms diatoms possess to dissipate excess energy. Its capacity is mainly defined by the xanthophyll cycle (XC) and Light-Harvesting Complex X (LHCX) proteins. Whereas the XC and its relation to NPQ have been relatively well-studied in both planktonic and benthic diatoms, our current knowledge about LHCX proteins and their potential involvement in NPQ regulation is largely restricted to planktonic diatoms. While recent studies using immuno-blotting have revealed the presence of light regulated LHCX proteins in benthic diatom communities and isolates, nothing is as yet known about the diversity, identity and transcriptional regulation or function of these proteins. We identified LHCX genes in the draft genome of the model benthic diatom Seminavis robusta and followed their transcriptional regulation during a day/night cycle and during exposure to high light conditions. The S. robusta genome contains 17 LHCX sequences, which is much more than in the sequenced planktonic model diatoms (4-5), but similar to the number of LHCX genes in the sea ice associated diatom Fragilariopsis cylindrus. LHCX diversification in both species, however, appears to have occurred independently. Interestingly, the S. robusta genome contains LHCX genes that are related to the LHCX6 of the model centric diatom Thalassiosira pseudonana, which are lacking in the well-studied pennate model diatom Phaeodactylum tricornutum. All investigated LHCX genes, with exception of SrLHCX6, were upregulated during the daily darklight transition. Exposure to 2,000 µmol photons m −2 s −1 , furthermore, increased transcription of all investigated LHCX genes. Our data suggest that the diversification and involvement of several light regulated LHCX genes in the photophysiology of S. robusta may represent an adaptation to the complex and highly variable light environment this benthic diatom species can be exposed to.

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Behavioural versus physiological photoprotection in epipelic and epipsammic benthic diatoms

Cited by 29 publications

References 46 publications

The Vertical Migratory Rhythm of Intertidal Microphytobenthos in Sediment Depends on the Light Photoperiod, Intensity, and Spectrum: Evidence for a Positive Effect of Blue Wavelengths

The Vertical Migratory Rhythm of Intertidal Microphytobenthos in Sediment Depends on the Light Photoperiod, Intensity, and Spectrum: Evidence for a Positive Effect of Blue Wavelengths

Effect of Light Intensity and Light Quality on Diatom Behavioral and Physiological Photoprotection

Light Regulation of LHCX Genes in the Benthic Diatom Seminavis robusta

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