scholarly journals Antioxidant and Photoprotection Networking in the Coastal Diatom Skeletonema marinoi

Antioxidants ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 154 ◽  
Author(s):  
Arianna Smerilli ◽  
Sergio Balzano ◽  
Maira Maselli ◽  
Martina Blasio ◽  
Ida Orefice ◽  
...  
Keyword(s):  
External Forcing ◽  
Light Conditions ◽  
Cosmetic Products ◽  
Low Light ◽  
Physiological Regulation ◽  
Wave Distribution ◽  
Role Of Light ◽  
Antioxidant Molecule ◽  
Skeletonema Marinoi

Little is known on the antioxidant activity modulation in microalgae, even less in diatoms. Antioxidant molecule concentrations and their modulation in microalgae has received little attention and the interconnection between light, photosynthesis, photoprotection, and antioxidant network in microalgae is still unclear. To fill this gap, we selected light as external forcing to drive physiological regulation and acclimation in the costal diatom Skeletonema marinoi. We investigated the role of light regime on the concentration of ascorbic acid, phenolic compounds and among them flavonoids and their connection with photoprotective mechanisms. We compared three high light conditions, differing in either light intensity or wave distribution, with two low light conditions, differing in photoperiod, and a prolonged darkness. The change in light distribution, from sinusoidal to square wave distribution was also investigated. Results revealed a strong link between photoprotection, mainly relied on xanthophyll cycle operation, and the antioxidant molecules and activity modulation. This study paves the way for further investigation on the antioxidant capacity of diatoms, which resulted to be strongly forced by light conditions, also in the view of their potential utilization in nutraceuticals or new functional cosmetic products.

scholarly journals Transcriptomics-Aided Dissection of the Intracellular and Extracellular Roles of Microcystin in Microcystis aeruginosa PCC 7806

2014 ◽  
Vol 81 (2) ◽  
pp. 544-554 ◽  
Author(s):  
A. Katharina Makower ◽  
J. Merijn Schuurmans ◽  
Detlef Groth ◽  
Yvonne Zilliges ◽  
Hans C. P. Matthijs ◽  
...  
Keyword(s):  
Polyketide Synthase ◽  
Wild Type Strain ◽  
Carbon Limitation ◽  
Light Conditions ◽  
Wild Type ◽  
Low Light ◽  
Content Type ◽  
Expression Of Genes ◽  
Polyketide Synthase Gene

ABSTRACTRecent studies have provided evidence for both intracellular and extracellular roles of the potent hepatotoxin microcystin (MC) in the bloom-forming cyanobacteriumMicrocystis. Here, we surveyed transcriptomes of the wild-type strainM. aeruginosaPCC 7806 and the microcystin-deficient ΔmcyBmutant under low light conditions with and without the addition of external MC of the LR variant (MC-LR). Transcriptomic data acquired by microarray and quantitative PCR revealed substantial differences in the relative expression of genes of the central intermediary metabolism, photosynthesis, and energy metabolism. In particular, the data provide evidence for a lower photosystem I (PSI)-to-photosystem II (PSII) ratio and a more pronounced carbon limitation in the microcystin-deficient mutant. Interestingly, only 6% of the transcriptional differences could be complemented by external microcystin-LR addition. This MC signaling effect was seen exclusively for genes of the secondary metabolism category. The orphan polyketide synthase gene cluster IPF38-51 was specifically downregulated in response to external MC-LR under low light. Our data suggest a hierarchical and light-dependent cross talk of secondary metabolites and support both an intracellular and an extracellular role of MC inMicrocystis.

Which Processes Sustain Biota in Open-Ocean Deep Chlorophyll Maxima?

2020 ◽  
Author(s):  
Shaun Rigby ◽  
Richard Williams ◽  
Eric Achterberg ◽  
Alessandro Tagliabue
Keyword(s):  
North Atlantic ◽  
Nutrient Deficiency ◽  
Marine Phytoplankton ◽  
Global Ocean ◽  
Light Conditions ◽  
Low Light ◽  
Cellular Iron ◽  
The Cost ◽  
Upward Flux

<p>Deep chlorophyll maxima (DCM) are productive layers widespread throughout the global ocean. In the DCM, marine phytoplankton are adapted to low light conditions at the cost of elevated cellular iron (Fe) requirements, leading to Fe deficient growth. To sustain productivity, nutrient demands must be met by sources such as the dissolution of sinking lithogenic particles, recycling of biogenic particles and physical transport from below. The <em>GEOTRACES</em> programme has expanded the global ocean datasets for a suite of trace metals and also noble gases. Here, we exploit helium measurements to derive a vertical flux estimate of nitrate (NO<sub>3</sub>), phosphate (PO<sub>4</sub>), silica (Si) and Fe into the DCM in the subtropical North Atlantic and equatorial Pacific. We apply the Si* relation to show differences in nutrient deficiency between waters in the DCM and the upward flux into the DCM. The offset in Si* between the DCM and upward flux may be enhanced or reduced by the dissolution of sinking particles or internal recycling. We show that the upward Fe flux to the DCM is of similar magnitude to Fe supplied through regeneration. In contrast, we show that the upward Fe flux outweighs estimates of Fe supplied to the DCM via recycling or lithogenic particles in the subtropical North Atlantic. The muted role of lithogenic particles in our estimates leads to the question: what assumptions must be made about aeolian deposition to increase the relevance of lithogenic particles at the DCM?</p>

scholarly journals Pruning Date and Cane Density Affect Primocane Development and Yield of `Autumn Bliss' Red Raspberry

HortScience ◽  
2004 ◽  
Vol 39 (3) ◽  
pp. 520-524 ◽  
Author(s):  
Pedro B. Oliveira ◽  
Cristina M. Oliveira ◽  
António A. Monteiro
Keyword(s):  
Environmental Factor ◽  
Plant Productivity ◽  
Rubus Idaeus ◽  
High Density ◽  
Assimilation Rate ◽  
Light Conditions ◽  
Red Raspberry ◽  
Low Light ◽  
Carbohydrate Reserves

The aim of this study was to determine the effects of date of summer pruning and cane densities on growth and fruiting characteristics of the raspberry (Rubus idaeus) plant. Three summer-pruning dates (early, middle, and late July) and four cane densities (8, 16, 24, and 32 canes/m row) were imposed to the greenhouse-grown primocane-fruiting raspberry `Autumn Bliss' in 2 consecutive years (1994 and 1995). A higher light microclimate and CO2 assimilation rate were measured within the canopy at the lowest density. Some compensation in CO2 assimilation rates were observed in the upper leaves of the high-density treatments, probably in response to low light. Delayed pruning decreased yield per cane and per row. The highest yields per cane were always observed at the lowest cane density. Densities of 16 and 24 canes/m produced the highest fruit yield. Light conditions appeared to be the most important environmental factor affecting plant productivity. Fruit were a weaker sink than roots; therefore, the role of carbohydrate reserves should be investigated.

scholarly journals What big eyes you have: the ecological role of giant pterygotid eurypterids

2014 ◽  
Vol 10 (7) ◽  
pp. 20140412 ◽  
Author(s):  
Ross P. Anderson ◽  
Victoria E. McCoy ◽  
Maria E. McNamara ◽  
Derek E. G. Briggs
Keyword(s):  
Visual Acuity ◽  
Compound Eyes ◽  
Ecological Role ◽  
Light Conditions ◽  
Low Light ◽  
Large Size ◽  
Arthropod Predators ◽  
High Level

Eurypterids are a group of extinct chelicerates that ranged for over 200 Myr from the Ordovician to the Permian. Gigantism is common in the group; about 50% of families include taxa over 0.8 m in length. Among these were the pterygotids (Pterygotidae), which reached lengths of over 2 m and were the largest arthropods that ever lived. They have been interpreted as highly mobile visual predators on the basis of their large size, enlarged, robust chelicerae and forward-facing compound eyes. Here, we test this interpretation by reconstructing the visual capability of Acutiramus cummingsi (Pterygotidae) and comparing it with that of the smaller Eurypterus sp. (Eurypteridae), which lacked enlarged chelicerae, and other arthropods of similar geologic age. In A. cummingsi , there is no area of lenses differentiated to provide increased visual acuity, and the interommatidial angles (IOA) do not fall within the range of high-level modern arthropod predators. Our results show that the visual acuity of A. cummingsi is poor compared with that of co-occurring Eurypterus sp. The ecological role of pterygotids may have been as predators on thin-shelled and soft-bodied prey, perhaps in low-light conditions or at night.

Assessing the role of light availability in the regeneration of Araucaria angustifolia (Araucariaceae)

2002 ◽  
Vol 50 (6) ◽  
pp. 741 ◽  
Author(s):  
L. S. Duarte ◽  
L. R. Dillenburg ◽  
L. M. G. Rosa
Keyword(s):  
Forest Succession ◽  
Light Availability ◽  
Canopy Cover ◽  
Native Forest ◽  
Araucaria Angustifolia ◽  
Light Conditions ◽  
Area Index ◽  
Species Tolerance ◽  
Role Of Light

The role of Brazilian pine (Araucaria angustifolia) in the process of forest succession is a topic of increasing controversy. While some authors consider the species to be pioneer, others consider it to be a climax species in relict temperate forests. We designed a field experiment to assess the role of light availability on the regeneration of A. angustifolia. The following three forests, with contrasting patterns of the species regeneration, were selected at a National Forest in southern Brazil: a Pinus plantation, an Araucaria plantation and a native araucarian forest. We analysed the population structure of Brazilian pine, the vegetation architecture, the light regime experienced by seedlings and the height growth of seedlings and sprouts. Brazilian pine colonisation and regeneration were observed in the Pinus and Araucaria plantations, respectively. No seedlings were found in the native forest. The greatest foliage area index and canopy cover were found in the native forest and the smallest in the Pinus plantation. In spite of the architectural differences, the native forest and the Araucaria plantation had similar light conditions and they both had lower levels of irradiances than the Pinus plantation. Seedlings and sprouts of Brazilian pine were found to occupy spots in the Araucaria plantation with canopy cover greater than the average forest conditions. Considering the similarity of understorey light conditions between the Araucaria plantation and the native forest (where no regeneration was taking place), we concluded that light availability was not limiting the regeneration of the species. Tolerance to shading and other aspects of the species indicate that Brazilian pine is not strictly heliophyllous and pioneer and is able to be established in the forest understorey.

scholarly journals The Role of Selected Wavelengths of Light in the Activity of Photosystem II in Gloeobacter violaceus

2021 ◽  
Vol 22 (8) ◽  
pp. 4021
Author(s):  
Monika Kula-Maximenko ◽  
Kamil Jan Zieliński ◽  
Ireneusz Ślesak
Keyword(s):  
Photosystem Ii ◽  
Spectral Composition ◽  
Photosynthetic Electron Transport ◽  
Metabolic Energy ◽  
Light Conditions ◽  
Gloeobacter Violaceus ◽  
Transport Chain ◽  
Cyanobacterial Culture ◽  
Photosynthetic Antennas

Gloeobacter violaceus is a cyanobacteria species with a lack of thylakoids, while photosynthetic antennas, i.e., phycobilisomes (PBSs), photosystem II (PSII), and I (PSI), are located in the cytoplasmic membrane. We verified the hypothesis that blue–red (BR) light supplemented with a far-red (FR), ultraviolet A (UVA), and green (G) light can affect the photosynthetic electron transport chain in PSII and explain the differences in the growth of the G. violaceus culture. The cyanobacteria were cultured under different light conditions. The largest increase in G. violaceus biomass was observed only under BR + FR and BR + G light. Moreover, the shape of the G. violaceus cells was modified by the spectrum with the addition of G light. Furthermore, it was found that both the spectral composition of light and age of the cyanobacterial culture affect the different content of phycobiliproteins in the photosynthetic antennas (PBS). Most likely, in cells grown under light conditions with the addition of FR and G light, the average antenna size increased due to the inactivation of some reaction centers in PSII. Moreover, the role of PSI and gloeorhodopsin as supplementary sources of metabolic energy in the G. violaceus growth is discussed.

Changes in the Stoichiometry of Photosystem II Components as an Adaptive Response to High-Light and Low-Light Conditions during Growth

1986 ◽  
Vol 41 (5-6) ◽  
pp. 597-603 ◽  
Author(s):  
Aloysius Wild ◽  
Matthias Höpfner ◽  
Wolfgang Rühle ◽  
Michael Richter
Keyword(s):  
Photosystem Ii ◽  
Functional Organization ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Molar Ratio ◽  
Light Conditions ◽  
Low Light ◽  
Pigment System ◽  
Transport Chain ◽  
The One

The effect of different growth light intensities (60 W·m-2, 6 W·m-2) on the performance of the photosynthetic apparatus of mustard plants (Sinapis alba L.) was studied. A distinct decrease in photosystem II content per chlorophyll under low-light conditions compared to high-light conditions was found. For P-680 as well as for Oᴀ and Oв protein the molar ratio between high-light and low-light plants was 1.4 whereas the respective concentrations per chlorophyll showed some variations for P-680 and Oᴀ on the one and Oв protein on the other hand.In addition to the study of photosystem II components, the concentrations of PQ, Cyt f, and P-700 were measured. The light regime during growth had no effect on the amount of P-700 per chlorophyll but there were large differences with respect to PQ and Cyt f. The molar ratio for Cyt f and PQ between high- and low-light leaves was 2.2 and 1.9, respectively.Two models are proposed, showing the functional organization of the pigment system and the electron transport chain in thylakoids of high-light and low-light leaves of mustard plants.

scholarly journals Assessing the Role of Light Absorption in Laser Lithotripsy by Isotopic Substitution of Kidney Stone Materials

2020 ◽  
Vol 6 (9) ◽  
pp. 5274-5280
Author(s):  
Sorout Shalini ◽  
Derek S. Frank ◽  
Ali H. Aldoukhi ◽  
Sami E. Majdalany ◽  
William W. Roberts ◽  
...  
Keyword(s):  
Light Absorption ◽  
Kidney Stone ◽  
Laser Lithotripsy ◽  
Isotopic Substitution ◽  
Stone Materials ◽  
Role Of Light
Sign in / Sign up

Export Citation Format

Share Document