scholarly journals Effects of iron availability on pigment signature and biogenic silica production in the coastal diatom Chaetoceros gracilis

2013 ◽  
Vol 4 (1) ◽  
pp. 20 ◽  
Author(s):  
Haimanti Biswas ◽  
Debasmita Bandyopadhyaya
Keyword(s):  
Chlorophyll A ◽  
Biogenic Silica ◽  
Light Harvesting ◽  
Silica Content ◽  
Supplementary Information ◽  
Iron Availability ◽  
Iron Stress ◽  
Iron Supply ◽  
Chaetoceros Gracilis ◽  
Pigment Ratios

The effects of iron availability on pigment signature and biogenic silica production were investigated for the first time in the coastal diatom Chaetoceros gracilis (isolated from the SW coast of the Bay of Bengal, India). Results revealed that increase in iron supply considerably increases chlorophyll a based specific growth rates, whereas, it decreases the values of diatoxanthin index and photoprotective to light harvesting pigment ratios. It is likely that, under iron stress C. gracilis activated a strong photoprotection mechanism by maximising the conversion of diadinoxanthin to diatoxanthin and by increasing overall amount of photoprotective pigments relative to light harvesting pigments. The xanthophyll cycle comprising of diadinoxanthin and diatoxanthin seems to be the principal photoprotective mechanism in C. gracilis and is consistent with some earlier studies. It is suggested that under iron limited conditions the diatoxanthin index and the ratio of photoprotective to light harvesting pigments can be used as physiological markers for iron stress in C. gracilis. The ratios of biogenic silica to chlorophyll a were considerably decreased with increasing iron supply indicating the possibility of reduced cellular silica content under iron enriched conditions; however, supplementary information is required to confirm this observation.

High-Resolution electron crystallography of the light-harvesting chlorophyll-a/b protein complex from chloroplast membranes

1990 ◽  
Vol 48 (1) ◽  
pp. 610-610
Author(s):  
Werner Kühlbrandt ◽  
Da Neng Wang ◽  
K.H. Downing
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Chlorophyll A ◽  
Protein Complex ◽  
Structural Integrity ◽  
Light Harvesting ◽  
Lhc Ii ◽  
Diffraction Patterns ◽  
Difference Fourier ◽  
2D Crystals

The light-harvesting chlorophyll-a/b protein complex (LHC-II) is the most abundant membrane protein in the chloroplasts of green plants where it functions as a molecular antenna of solar energy for photosynthesis. We have grown two-dimensional (2d) crystals of the purified, detergent-solubilized LHC-II . The crystals which measured 5 to 10 μm in diameter were stabilized for electron microscopy by washing with a 0.5% solution of tannin. Electron diffraction patterns of untilted 2d crystals cooled to 130 K showed sharp spots to 3.1 Å resolution. Spot-scan images of 2d crystals were recorded at 160 K with the Berkeley microscope . Images of untilted crystals were processed, using the unbending procedure by Henderson et al . A projection map of the complex at 3.7Å resolution was generated from electron diffraction amplitudes and high-resolution phases obtained by image processing .A difference Fourier analysis with the same image phases and electron diffraction amplitudes recorded of frozen, hydrated specimens showed no significant differences in the 3.7Å projection map. Our tannin treatment therefore does not affect the structural integrity of the complex.

scholarly journals The redox-controlled light-harvesting chlorophyll a/b protein kinase. Deactivation by substituted quinones.

1992 ◽  
Vol 267 (36) ◽  
pp. 25908-25915
Author(s):  
D Frid ◽  
A Gal ◽  
W Oettmeier ◽  
G Hauska ◽  
S Berger ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Chlorophyll A ◽  
Light Harvesting

scholarly journals Proteome Analysis for Understanding Abiotic Stress (Salinity and Drought) Tolerance in Date Palm (Phoenix dactyliferaL.)

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Haddad A. El Rabey ◽  
Abdulrahman L. Al-Malki ◽  
Khalid O. Abulnaja ◽  
Wolfgang Rohde
Keyword(s):  
Drought Stress ◽  
Chlorophyll A ◽  
Date Palm ◽  
Light Harvesting ◽  
Binding Protein ◽  
Proteome Analysis ◽  
Rubisco Activase ◽  
Stress Conditions ◽  
Spectrometric Analysis ◽  
Salt And Drought Stress

This study was carried out to study the proteome of date palm under salinity and drought stress conditions to possibly identify proteins involved in stress tolerance. For this purpose, three-month-old seedlings of date palm cultivar “Sagie” were subjected to drought (27.5 g/L polyethylene glycol 6000) and salinity stress conditions (16 g/L NaCl) for one month. DIGE analysis of protein extracts identified 47 differentially expressed proteins in leaves of salt- and drought-treated palm seedlings. Mass spectrometric analysis identified 12 proteins; three out of them were significantly changed under both salt and drought stress, while the other nine were significantly changed only in salt-stressed plants. The levels of ATP synthase alpha and beta subunits, an unknown protein and some of RubisCO fragments were significantly changed under both salt and drought stress conditions. Changes in abundance of superoxide dismutase, chlorophyll A-B binding protein, light-harvesting complex1 protein Lhca1, RubisCO activase, phosphoglycerate kinase, chloroplast light-harvesting chlorophyll a/b-binding protein, phosphoribulokinase, transketolase, RubisCO, and some of RubisCO fragments were significant only for salt stress.

scholarly journals Silicon cycle in the tropical South Pacific: contribution to the global Si cycle and evidence for an active pico-sized siliceous plankton

2018 ◽  
Vol 15 (18) ◽  
pp. 5595-5620 ◽  
Author(s):  
Karine Leblanc ◽  
Véronique Cornet ◽  
Peggy Rimmelin-Maury ◽  
Olivier Grosso ◽  
Sandra Hélias-Nunige ◽  
...  
Keyword(s):  
Community Structure ◽  
Chlorophyll A ◽  
Biogenic Silica ◽  
New Caledonia ◽  
Size Fraction ◽  
South Pacific ◽  
Size Class ◽  
Biogeochemical Cycle ◽  
Standing Stocks ◽  
Negligible Contribution

Abstract. This article presents data regarding the Si biogeochemical cycle during two oceanographic cruises conducted in the tropical South Pacific (BIOSOPE and OUTPACE cruises) in 2005 and 2015. It involves the first Si stock measurements in this understudied region, encompassing various oceanic systems from New Caledonia to the Chilean upwelling between 8 and 34∘ S. Some of the lowest levels of biogenic silica standing stocks ever measured were found in this area, notably in the southern Pacific gyre, where Chlorophyll a concentrations are the most depleted worldwide. Integrated biogenic silica stocks are as low as 1.08±0.95 mmol m−2 and are the lowest stocks measured in the South Pacific. Size-fractionated biogenic silica concentrations revealed a non-negligible contribution of the pico-sized fraction (<2–3 µm) to biogenic silica standing stocks, representing 26%±12% of total biogenic silica during the OUTPACE cruise and 11%±9% during the BIOSOPE cruise. These results indicate significant accumulation in this size class, which was undocumented for 2005, but has since then been related to Si uptake by Synechococcus cells. Si uptake measurements carried out during BIOSOPE confirmed biological Si uptake by this size fraction. We further present diatoms community structure associated with the stock measurements for a global overview of the Si cycle in the tropical South Pacific.

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