Movatterモバイル変換

[0]ホーム
URL:

Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
Thehttps:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

NIH NLM Logo
Log inShow account info
Access keysNCBI HomepageMyNCBI HomepageMain ContentMain Navigation
pubmed logo
Advanced Clipboard
User Guide

Full text links

Atypon full text link Atypon Free PMC article
Full text links

Actions

Share

.2008 Sep 9;105(36):13674-8.
doi: 10.1073/pnas.0805187105. Epub 2008 Aug 29.

Enhanced photoprotection pathways in symbiotic dinoflagellates of shallow-water corals and other cnidarians

Affiliations

Enhanced photoprotection pathways in symbiotic dinoflagellates of shallow-water corals and other cnidarians

Jennifer McCabe Reynolds et al. Proc Natl Acad Sci U S A..

Erratum in

  • Proc Natl Acad Sci U S A. 2008 Nov 4;105(44):17206

Abstract

Photoinhibition, exacerbated by elevated temperatures, underlies coral bleaching, but sensitivity to photosynthetic loss differs among various phylotypes of Symbiodinium, their dinoflagellate symbionts. Symbiodinium is a common symbiont in many cnidarian species including corals, jellyfish, anemones, and giant clams. Here, we provide evidence that most members of clade A Symbiodinium, but not clades B-D or F, exhibit enhanced capabilities for alternative photosynthetic electron-transport pathways including cyclic electron transport (CET). Unlike other clades, clade A Symbiodinium also undergo pronounced light-induced dissociation of antenna complexes from photosystem II (PSII) reaction centers. We propose these attributes promote survival of most cnidarians with clade A symbionts at high light intensities and confer resistance to bleaching conditions that conspicuously impact deeper dwelling corals that harbor non-clade A Symbiodinium.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
SIP detection of postillumination PQ reduction in clade A but not BSymbiodinium in culture andin hospice. Dark-adapted cultured cells and corals were subjected to saturating light pulses every 20 s after applying low-intensity ML. A progressive increase inF0′ levels reflect substantial reduction of the PQ pool in clade A3 cultured cells (A) but not in clade B1 cultured cells (B). (Insets) Light-induced PQ oxidation and dark rereduction between the 13th and 15th saturating pulses in clade A but not clade B phylotypes. (A andB) After clade A3 SIP treatment, 50 μM MV was used in combination with FR. (C andD) A Diving-PAM was used for SIP with dark-adapted corals. (C)Symbiodinium phylotype A4a in shallow-dwellingP. astreoides exhibits progressive PQ reduction and postillumination PQ reduction. (D) Fluorescence responses ofM. faveolata harboring B1Symbiodinium show no change with SIP.
Fig. 2.
Fig. 2.
Detection of clade ASymbiodinium in coral hosts. SIP of dark-adaptedP. furcata, from a 1-m depth, reveals a fluorescence pattern typical of clade A. (A) Genetic analysis by using DGGE revealed the presence of a combination of A4a and some B1 phylotypes ofSymbiodinium. (B) Dark-adaptedP. furcata from a 1.5-m depth, and found to harbor only B1Symbiodinium, does not display a clade A specific fluorescence pattern SIP response.
Fig. 3.
Fig. 3.
Enhanced dark PQ reduction in anaerobic clade ASymbiodinium. After dark incubation for 10 min and supplementation with 10 mM bicarbonate to maximize carbon fixation, cultures of subclades A3 (A andC) and B2 (B andD) were bubbled with air (A andB) or argon (C andD) to impose aerobic and anaerobic conditions, respectively. Fluorescence decreases after onset of continuous actinic illumination reflect NPQ processes, which are almost complete after 5-min exposure to 250 μmol quanta m−2 s−1. During subsequent darkness, anaerobic clade A (C) and, to a lesser extent, both aerobic and anaerobic clade B exhibit PQ reduction (B andD).
Fig. 4.
Fig. 4.
Light-Induced PCP and Intrinsic LHC Dissociation from PSII in clade A3Symbiodinium. (A) The 77 K fluorescence emission spectra at excitation wavelengths 440 nm (solid line) and 530 nm (dashed line). (B) Excitation spectra of the same clade A3 cells detected at 673 nm (solid line) and 683 nm (dashed line) after 60-min dark adaptation. The dark-acclimated excitation spectrum, specifically the peridinin excitation shoulder at 530 nm, is higher at 683 nm than 673 nm as a result of the greater PSII connectivity of the PCP antenna complexes and resulting fluorescence. (C) Fluorescence emission spectra at excitation wavelengths of 440 nm (solid line) and 530 nm (dashed line) after exposure to 100 min of white light. The two emission peaks (675 and 686 nm) in both excitation spectra from white light-adapted clade A3 cells reflect partial dissociation of LHCs from PSII. Prolonged FR illumination (>690 nm) results in further loss of PSII 686 nm fluorescence, whereas 683-nm emission from PCPs and intrinsic LHCs is enhanced (solid line). No far-red-induced fluorescence shifts occur in clade B (dotted-dashed line). (D) Fluorescence excitation spectra of the same clade A3 cells as inC at detection wavelengths of 673 nm (solid line) and 683 nm (dashed line) after 100 min of actinic light exposure, showing a pronounced peridinin contribution to 675-nm emission by 530-nm excitation in comparison with that of dark-adapted cells inB.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Stat M, Carter D, Hoegh-Guldberg O. The evolutionary history of Symbiodinium and scleractinian hosts - Symbiosis, diversity, and the effect of climate change. Perspect Plant Ecol Evol System. 2006;8:23–43.
    1. Lesser MP. Experimental biology of coral reef ecosystems. J Exp Mar Biol Ecol. 2004;300:217–252.
    1. Iglesias-Prieto R, et al. Different algal symbionts explain the vertical distribution of dominant reef corals in the eastern Pacific. Proc R Soc London Ser B. 2004;271:1757–1763. - PMC - PubMed
    1. LaJeunesse TC. Diversity and community structure of symbiotic dinoflagellates from Caribbean coral reefs. Mar Biol. 2002;141:387–400.
    1. LaJeunesse TC, et al. Low symbiont diversity in southern Great Barrier Reef corals, relative to those of the Caribbean. Limnol Oceanogr. 2003;48:2046–2054.

Publication types

MeSH terms

Substances

Related information

LinkOut - more resources

Full text links
Atypon full text link Atypon Free PMC article
Cite
Send To

NCBI Literature Resources

MeSHPMCBookshelfDisclaimer

The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Unauthorized use of these marks is strictly prohibited.

[8]ページ先頭
©2009-2025 Movatter.jp