Photosynthetic Capacities and Photosynthetic Action Spectra of Endozoic Algae of the Massive Coral Favia

Halldal, Per

doi:10.2307/1539860

Cited by 150 publications

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“…1). The likely source of this pigment was endolithic green algae (Halldal 1968;Jeffrey 1968). Green algae do not contain Chl c, peridinin, or diadinoxanthin (pigments of dinoflagellate zooxanthellae), but they do contain Chl a.…”

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confidence: 99%

Changes in pigmentation associated with the bleaching of stony corals

Kleppel¹,

Dodge²,

Reese³

1989

Limnology & Oceanography

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Bleaching (loss of pigmentation) is a common response by corals to environmental stress. Changes in pigmentation and the processes that caused them were studied in Montastrea annularis during a natural bleaching event off southeast Florida. Chlorophyll c, peridinin, and diadinoxanthin levels were 35, 17, and 20 times higher in normal corals than in bleached ones. Two processes, loss of zooxanthellae from the coral and loss of pigments from the remaining zooxanthellae, contributed to bleaching. Loss of zooxanthellar pigment accounted for 72% of the decrease in Chl c. The two processes contributed about equally to reduced carotenoid levels.

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confidence: 99%

Changes in pigmentation associated with the bleaching of stony corals

Kleppel¹,

Dodge²,

Reese³

1989

Limnology & Oceanography

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“…For example, chlorophyll a has an absorption peak at 663 nm when diluted in acetone and in monomeric state (19). This peak is red-shifted in vivo to 680 nm and in some cases to even longer wavelengths, as high as 720 nm (20).…”

Section: Discussionmentioning

confidence: 99%

Surface biosignatures of exo-Earths: Remote detection of extraterrestrial life

Hegde

Paulino-Lima

Kent

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Exoplanet discovery has made remarkable progress, with the first rocky planets having been detected in the central star's liquid water habitable zone. The remote sensing techniques used to characterize such planets for potential habitability and life rely solely on our understanding of life on Earth. The vegetation red edge from terrestrial land plants is often used as a direct signature of life, but it occupies only a small niche in the environmental parameter space that binds life on present-day Earth and has been widespread for only about 460 My. To more fully exploit the diversity of the one example of life known, we measured the spectral characteristics of 137 microorganisms containing a range of pigments, including ones isolated from Earth's most extreme environments. Our database covers the visible and near-infrared to the short-wavelength infrared (0.35-2.5 μm) portions of the electromagnetic spectrum and is made freely available from biosignatures. astro.cornell.edu. Our results show how the reflectance properties are dominated by the absorption of light by pigments in the visible portion and by strong absorptions by the cellular water of hydration in the infrared (up to 2.5 μm) portion of the spectrum. Our spectral library provides a broader and more realistic guide based on Earth life for the search for surface features of extraterrestrial life. The library, when used as inputs for modeling disk-integrated spectra of exoplanets, in preparation for the next generation of space-and ground-based instruments, will increase the chances of detecting life.biosignatures | spectral library | reflectivity | extremophiles | pigments I n the last decade, the field of exoplanet research has transitioned rapidly from detection to detection and characterization, with the first rocky exoplanets detected in the central star's liquid water habitable zone. Much of the excitement of this research in both the astrobiology community and the general public is motivated by the quest to discover a second genesis of life. The great distances that separate us from even the most nearby stars dictate that all measurements of the exoplanet must be made through remote sensing techniques for the foreseeable future. Thus, it is critical for us to determine the types of biosignatures that we should be looking for when designing the next generation of ground-and space-based instruments that will observe these planets at high spectral and possibly spatial resolutions.Since the mid-1960s a primary life-searching strategy has been to look for a specific combination of an oxidizing and a reducing gas in the exoplanetary atmosphere, such as the O 2 and CH 4 in our atmosphere, because this is a thermodynamically unstable situation suggesting that an active agent such as life is responsible for the chemical disequilibrium (1, 2). Of particular interest, both from an observational and modeling perspective, is to complement those indirect life detection studies with surface features that are direct properties of the organisms themselves (3).Alt...

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“…Although this phenomenon is common in the blue peak of some carotenoids (i.e. pendinin and fucoxanthin), it has not been reported for the red peak of algal chlorophylls or their derivatives in natural samples except for symbionts of the coral Favia (Halldal 1968). On the other hand, a shift to shorter wavelengths from in vivo to in vitro absorption has been observed in bacteriochlorophylls (Brock & Madigan 1991).…”

Section: Chlorophyll Degradation Hypothesismentioning

confidence: 98%

Evidence for a novel pigment with in vivo absorption maximum at 708 nm associated with Phaeocystis cf. pouchetii blooms

Vernet¹,

Mitchell²,

Sakshaug³

et al. 1996

Mar. Ecol. Prog. Ser.

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ABSTRACT. The presence of a chlorophyll a-like (chl a) plgment, with a n in vivo absorption maximum in the near-infrared region a t 708 to 712 nm, was observed mainly in sedimenting material and Calanus hyperboreus fecal pellets associated with Phaeocystis cf. pouchetli Hariot blooms. (In vivo absorption is attributed to natural absorption found in naturally occurring particulate matter and seston. In vitro absorption refers to extracts in organic solvents.) This absorption peak was observed in conjunction with the absorption peak at 674 to 676 nm, commonly attributed to chl a and its derivatives. The in vivo absorption maximum in the near Infrared, centered around 708 nm, was observed only in particulate matter and not in methanolic and aqueous acetonic extracts Absorption efficiency (Q,) of individual particles measured by microphotometry revealed particles 3 to 4 pm In diameter with an in vivo absorption maximum at 708 to 713 nm and no in vivo absorption peak at 676 nm, as clxpected for chlorophylls and its phaeopigments, indicating a dlfferent type of particle in the sample. The visible spectrum also had a broad absorption peak in the blue region, between 420 and 450 nm, suggesting a chlorophyll-like spectrum. The main chl degradation product analyzed by high-performance liquid chromatography of sedimenting matter was identified as a phaeophorbide a-like pigment, with absorption maximum in the red at 665 to 666 nm in organic solvents, with no indication of a pigment with in vitro absorption properties in the near infrared. The accumulation of the 708 nm in VIVO absorption peak in particles associated w~t h P cf poucheliiseems to be a widespread feature as lt was observed during 3 different cruises to the Barents Sea, Fram Strait and the Kattegat. We propose 3 dlfferent hypotheses on the origin of this novel peak in in vivo absorption not previously observed In marlne environments: (1) P cf pouchetii has a chl a breakdown pathway whlch promotes the accumulation of a known chl degradation product with an in v~voabsorption at 708 nm; (2) there is a new chl degradation product produced by grazing of C. hyperboreus on P cf. pouchetii, as yet to be isolated; and (3) there is a new pigment, synthesized by either P cf. pouchetii or another organism associated with this alga, during mature blooms of Phaeocystis. These hypotheses are discussed in vlew of the available evidence.

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Photosynthetic Capacities and Photosynthetic Action Spectra of Endozoic Algae of the Massive Coral Favia

Cited by 150 publications

References 0 publications

Changes in pigmentation associated with the bleaching of stony corals

Changes in pigmentation associated with the bleaching of stony corals

Surface biosignatures of exo-Earths: Remote detection of extraterrestrial life

Evidence for a novel pigment with in vivo absorption maximum at 708 nm associated with Phaeocystis cf. pouchetii blooms

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