Impacts of UV radiation on growth and photosynthetic carbon acquisition in Gracilaria lemaneiformis (Rhodophyta) under phosphorus-limited and replete conditions

2009 ◽  
Vol 36 (12) ◽  
pp. 1057 ◽  
Author(s):  
Zhiguang Xu ◽  
Kunshan Gao
Keyword(s):  
Growth Rate ◽  
Carbonic Anhydrase ◽  
Photosynthetic Efficiency ◽  
Inorganic Carbon ◽  
Inorganic Phosphorus ◽  
Gracilaria Lemaneiformis ◽  
Solar Ultraviolet Radiation ◽  
Relative Growth ◽  
Photosynthetic Carbon ◽  
Solar Ultraviolet

Solar ultraviolet radiation (UVR, 280–400 nm) is known to negatively affect macroalgal growth and photosynthesis, while phosphorus availability may affect their sensitivity to UVR. Here, we show that UV-A enhanced the growth rate of the red macroalga, Gracilaria lemaneiformis Bory de Saint-Vincent under inorganic phosphorus (Pi)-replete but reduced it under Pi-limited conditions. Maximal net photosynthetic rates were significantly reduced by both UV-A and UV-B, but the apparent photosynthetic efficiency was enhanced in the presence of UV-A. The UV-induced inhibition was exacerbated under Pi-limited conditions. The activity of total carbonic anhydrase was enhanced and the photosynthetic affinity for exogenous inorganic carbon (Ci) was raised for thalli grown in the presence of UVR under both Pi-replete and Pi-limited conditions. The relative growth rate was closely related to Ci acquisition capability (Vmax/KDIC), which was enhanced by UVR exposure under Pi-replete but not significantly affected under Pi-limited conditions.

THE ACQUISITION OF INORGANIC CARBON IN MARINE MACROPHYTES

1998 ◽  
Vol 46 (2) ◽  
pp. 83-87 ◽  
Author(s):  
Sven Beer
Keyword(s):  
Carbonic Anhydrase ◽  
Aquatic Plants ◽  
Inorganic Carbon ◽  
External Medium ◽  
Uptake Mechanism ◽  
Tropical Regions ◽  
Marine Macrophytes ◽  
Photosynthetic Carbon ◽  
Diffusion Rates ◽  
Carbon Transport

The low diffusion rates of solutes in water call for a separation of photosynthetic carbon acquirement in aquatic plants into carbon transport and the subsequent photosynthetic reduction of CO2. This paper will focus on the transport of inorganic carbon from the external medium to the site of fixation in marine macrophytes. In accord with the much higher concentration of HCO3− than of CO2 in seawater, most marine macrophytes can utilize the ionic carbon form for their photosynthetic needs. The two known ways of HCO, utilization are (a) via extracellular, carbonic anhydrase catalyzed dehydration of HCO3− to form CO2, which then diffuses into the photosynthesizing cells, and (b) by direct uptake via a transporter. While the first way may be sufficient to support low rates of photosynthesis in temperate regions, it is viewed as futile under situations where high temperatures and irradiances would cause a high pH to form close to the uptake site of carbon and where, consequently, the CO2/HCO3− ratio would be very low. Therefore, it may well be that the direct HCO3− uptake mechanism described for Ulva from more tropical regions confers an adaptational advantage under conditions conducive to higher photosynthetic rates.

Inorganic carbon acquisition by Chlamydomonas acidophila across a pH range

2005 ◽  
Vol 83 (7) ◽  
pp. 872-878 ◽  
Author(s):  
Elly Spijkerman
Keyword(s):  
Growth Rate ◽  
Carbonic Anhydrase ◽  
Inorganic Carbon ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Chlamydomonas Acidophila ◽  
Ph Conditions ◽  
Ph Range ◽  
Very High ◽  
External Ph

Chlamydomonas acidophila Negoro had a higher maximum growth rate upon aeration with 5% CO2 (v/v) than in nonaerated conditions at an external pH above 2. In medium with a pH of 1.0 or 2.0, a decrease in the maximum growth rate was observed upon CO2 aeration in comparison with nonaerated conditions. At both very low and very high external pH conditions, an induction of external carbonic anhydrase was detected; this being more pronounced in CO2-aerated cells than in nonaerated cells. It is therefore suggested that the induction of carbonic anhydrase is part of a stress response in Chlamydomonas acidophila. Comparison of some physiological characteristics of Chlamydomonas acidophila acclimated at pH 2.65 and at pH 6.0, revealed that CO2 aeration increased gross maximum photosynthesis at both pHs, whereas respiration, light acclimation, and photoinhibition were not effected. At pH 2.65, Chlamydomonas acidophila was found to have a carbon-concentrating mechanism under nonaerated conditions, whereas it did not under CO2-aerated conditions at pH 6. The affinity for CO2 use in O2 production was not dependent on CO2 aeration, but it was much lower at pH 6 than it was at pH 2.65. CO2 kinetic characteristics indicate that the photosynthesis of Chlamydomonas acidophila in its natural environment is not limited by inorganic carbon.Key words: Chlamydomonas acidophila, CCM, external carbonic anhydrase, photosynthesis, growth rates, pH stress, CO2.

Alleviation of solar ultraviolet radiation (UVR)-induced photoinhibition in diatom Chaetoceros curvisetus by ocean acidification

2014 ◽  
Vol 95 (4) ◽  
pp. 661-667 ◽  
Author(s):  
Heng Chen ◽  
Wanchun Guan ◽  
Guoquan Zeng ◽  
Ping Li ◽  
Shaobo Chen
Keyword(s):  
Growth Rate ◽  
Ultraviolet Radiation ◽  
Ocean Acidification ◽  
Specific Growth Rate ◽  
Cell Density ◽  
Specific Growth ◽  
Photochemical Efficiency ◽  
Solar Ultraviolet Radiation ◽  
Chaetoceros Curvisetus ◽  
Solar Ultraviolet

The study aimed to unravel the interaction between ocean acidification and solar ultraviolet radiation (UVR) in Chaetoceros curvisetus. Chaetoceros curvisetus cells were acclimated to high CO2 (HC, 1000 ppmv) and low CO2 concentration (control, LC, 380 ppmv) for 14 days. Cell density, specific growth rate and chlorophyll were measured. The acclimated cells were then exposed to PAB (photosynthetically active radiation (PAR) + UV-A + UV-B), PA (PAR + UV-A) or P (PAR) for 60 min. Photochemical efficiency (ΦPSII), relative electron transport rate (rETR) and the recovery of ΦPSII were determined. HC induced higher cell density and specific growth rate compared with LC. However, no difference was found in chlorophyll between HC and LC. Moreover, ΦPSII and rETRs were higher under HC than LC in response to solar UVR. P exposure led to faster recovery of ΦPSII, both under HC and LC, than PA and PAB exposure. It appeared that harmful effects of UVR on C. curvisetus could be counteracted by ocean acidification simulated by high CO2 when the effect of climate change is not beyond the tolerance of cells.

scholarly journals Thylakoid luminal θ-carbonic anhydrase critical for growth and photosynthesis in the marine diatom Phaeodactylum tricornutum

2016 ◽  
Vol 113 (35) ◽  
pp. 9828-9833 ◽  
Author(s):  
Sae Kikutani ◽  
Kensuke Nakajima ◽  
Chikako Nagasato ◽  
Yoshinori Tsuji ◽  
Ai Miyatake ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Phaeodactylum Tricornutum ◽  
Photosynthetic Efficiency ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Marine Diatom ◽  
Bisphosphate Carboxylase ◽  
Gfp Fusion Protein ◽  
Close Proximity ◽  
Esterase Activities

The algal pyrenoid is a large plastid body, where the majority of the CO2-fixing enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) resides, and it is proposed to be the hub of the algal CO2-concentrating mechanism (CCM) and CO2 fixation. The thylakoid membrane is often in close proximity to or penetrates the pyrenoid itself, implying there is a functional cooperation between the pyrenoid and thylakoid. Here, GFP tagging and immunolocalization analyses revealed that a previously unidentified protein, Pt43233, is targeted to the lumen of the pyrenoid-penetrating thylakoid in the marine diatom Phaeodactylum tricornutum. The recombinant Pt43233 produced in Escherichia coli cells had both carbonic anhydrase (CA) and esterase activities. Furthermore, a Pt43233:GFP-fusion protein immunoprecipitated from P. tricornutum cells displayed a greater specific CA activity than detected for the purified recombinant protein. In an RNAi-generated Pt43233 knockdown mutant grown in atmospheric CO2 levels, photosynthetic dissolved inorganic carbon (DIC) affinity was decreased and growth was constantly retarded; in contrast, overexpression of Pt43233:GFP yielded a slightly greater photosynthetic DIC affinity. The discovery of a θ-type CA localized to the thylakoid lumen, with an essential role in photosynthetic efficiency and growth, strongly suggests the existence of a common role for the thylakoid-luminal CA with respect to the function of diverse algal pyrenoids.

Simplified Calibration for Broadband Solar Ultraviolet Radiation Measurements¶

2003 ◽  
Vol 78 (6) ◽  
pp. 603 ◽  
Author(s):  
A. Oppenrieder ◽  
P. Hoeppe ◽  
P. Koepke ◽  
J. Reuder ◽  
J. Schween ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Solar Ultraviolet Radiation ◽  
Solar Ultraviolet ◽  
Radiation Measurements

Effect of caffeine on the growth and photosynthetic efficiency of marine macroalgae

2021 ◽  
Vol 64 (1) ◽  
pp. 13-18
Author(s):  
Ira Gray ◽  
Lindsay A. Green-Gavrielidis ◽  
Carol Thornber
Keyword(s):  
Growth Rate ◽  
Photosynthetic Efficiency ◽  
Sublethal Effects ◽  
Marine Species ◽  
Marine Organisms ◽  
Marine Macroalgae ◽  
Chondrus Crispus ◽  
Coastal Environments ◽  
Codium Fragile ◽  
High Concentrations

Abstract Caffeine is present in coastal environments worldwide and there is a need to assess its impact on marine organisms. Here, we exposed two species of ecologically important marine macroalgae (Chondrus crispus and Codium fragile subsp. fragile) to a suite of caffeine concentrations and measured their response. Caffeine concentrations of 10–100 ng L−1 had no significant effect on the growth rate or photosynthetic efficiency of either algae. Extremely high concentrations (100–200 mg L−1), which may occur acutely, produced sublethal effects for both species and mortality in C. fragile subsp. fragile. Our results highlight the need to understand how caffeine impacts marine species.

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