In situ phytoplankton absorption, fluorescence emission, and particulate backscattering spectra determined from reflectance

1995 ◽  
Vol 100 (C7) ◽  
pp. 13279 ◽  
Author(s):  
Collin S. Roesler ◽  
Mary Jane Perry
Keyword(s):  
Fluorescence Emission ◽  
Phytoplankton Absorption

In situ study of photoinhibition of photosynthesis and xanthophyll cycle activity in plants growing in natural gaps of the tropical forest

1998 ◽  
Vol 25 (2) ◽  
pp. 189 ◽  
Author(s):  
A. Thiele ◽  
G.H. Krause ◽  
K. Winter
Keyword(s):  
Chlorophyll A ◽  
Xanthophyll Cycle ◽  
Fluorescence Emission ◽  
D1 Protein ◽  
Barro Colorado Island ◽  
Slow Phase ◽  
Photoinhibition Of Photosynthesis ◽  
Total Carotenoids ◽  
Lowland Forest

Photoinhibition of photosynthesis was studied in situ in leaves of several species of plants growing in natural treefall gaps of a tropical lowland forest (Barro Colorado Island, Panama). Leaves showed several features typical of sun-acclimation: relatively high pools of total carotenoids and xanthophyll cycle pigments and high ratios of chlorophyll a to b. During 1–2 h periods of exposure to direct mid-day sun, all leaves experienced substantial photoinhibition as indicated by a marked decline in the ratio of variable to maximum chlorophyll a fluorescence emission, FV/FM, detected after 10 min of dark adaptation. After return to shade, these ‘dark-adapted’ FV/FM ratios increased with biphasic kinetics, similar to previous findings under controlled conditions in the laboratory. A phase lasting about 1 h accounted for most of the recovery of FV/FM and was followed by a slow phase which proceeded until sunset. The decline in FV/FM during photoinhibition and the fast phase of recovery correlated closely with the amounts of zeaxanthin in the leaves. Given the small portion of the second recovery phase which has previously been attributed to turnover of the D1 protein in Photosystem II, high xanthophyll cycle activity in these gap leaves is probably responsible for the major part of photoinhibition, providing an efficient energy dissipation pathway during periods of high sunlight exposure.

scholarly journals Spectral studies of ocean water using DOAS

2007 ◽  
Vol 4 (3) ◽  
pp. 459-489
Author(s):  
M. Vountas ◽  
T. Dinter ◽  
A. Bracher ◽  
J. P. Burrows ◽  
B. Sierk
Keyword(s):  
Spectral Studies ◽  
Optical Absorption Spectroscopy ◽  
Retrieval Technique ◽  
Phytoplankton Absorption ◽  
Visible Wavelengths ◽  
Scanning Imaging ◽  
Atmospheric Trace Gas ◽  
First Time ◽  
Chlorophyll Concentrations

Abstract. Methods enabling the retrieval of oceanic parameter from the space borne instrumentation Scanning Imaging Absorption Spectrometer for Atmospheric ChartographY (SCIAMACHY) using Differential Optical Absorption Spectroscopy (DOAS) are presented. SCIAMACHY onboard ENVISAT measures back scattered solar radiation at a spectral resolution (0.2 to 1.5 nm). The DOAS method was used for the first time to fit modelled Vibrational Raman Scattering (VRS) in liquid water and in situ measured phytoplankton absorption reference spectra to optical depths measured by SCIAMACHY. Spectral structures of VRS and phytoplankton absorption were clearly found in these optical depths. Both fitting approaches lead to consistent results. DOAS fits correlate with estimates of chlorophyll concentrations: low fit factors for VRS retrievals correspond to large chlorophyll concentrations and vice versa; large fit factors for phytoplankton absorption correspond with high chlorophyll concentrations and vice versa. From these results a simple retrieval technique taking advantage of both measurements is shown. First maps of global chlorophyll concentrations were compared to the corresponding MODIS measurements with very promising results. In addition, results from this study will be used to improve atmospheric trace gas DOAS-retrievals from visible wavelengths by including these oceanographic signatures.

scholarly journals Using Scuba for In Situ Determination of Chlorophyll Distributions in Corals by Underwater Near Infrared Fluorescence Imaging

2020 ◽  
Vol 8 (1) ◽  
pp. 53
Author(s):  
Thomas Oh ◽  
Jittiwat Sermsripong ◽  
Barry W. Hicks
Keyword(s):  
Fluorescence Imaging ◽  
Large Scale ◽  
Near Infrared ◽  
Fluorescent Proteins ◽  
Fluorescence Emission ◽  
Florida Keys ◽  
Nir Fluorescence ◽  
Novel Method ◽  
Near Infrared Fluorescence Imaging

Studies reporting quantitation and imaging of chlorophyll in corals using visible fluorescent emission in the red near 680 nm can suffer from competing emission from other red-emitting pigments. Here, we report a novel method of selectively imaging chlorophyll distributions in coral in situ using only the near infrared (NIR) fluorescence emission from chlorophyll. Commercially available equipment was assembled that allowed the sequential imaging of visible, visible-fluorescent, and NIR-fluorescent pigments on the same corals. The relative distributions of chlorophyll and fluorescent proteins (GFPs) were examined in numerous corals in the Caribbean Sea, the Egyptian Red Sea, the Indonesian Dampier Strait, and the Florida Keys. Below 2 m depth, solar induced NIR chlorophyll fluorescence can be imaged in daylight without external lighting, thus, it is much easier to do than visible fluorescence imaging done at night. The distributions of chlorophyll and GFPs are unique in every species examined, and while there are some tissues where both fluorophores are co-resident, often tissues are selectively enriched in only one of these fluorescent pigments. Although laboratory studies have clearly shown that GFPs can be photo-protective, their inability to prevent large scale bleaching events in situ may be due to their limited tissue distribution.

Physico-Chemical Studies of Isolated Chromatin Compared with in situ Chromatin after Partial Hepatectomy in the Rat

1979 ◽  
Vol 34 (5-6) ◽  
pp. 442-448 ◽  
Author(s):  
Paul Miller ◽  
Walfried A. Linden ◽  
Claudio Nicolini
Keyword(s):  
Partial Hepatectomy ◽  
Conformational Changes ◽  
Quaternary Structure ◽  
Cultured Cells ◽  
Fluorescence Emission ◽  
Chromatin Organization ◽  
Chromatin Conformation ◽  
Functional Changes

Abstract Chromatin was isolated from rat liver cells at 0, 3, 5, 11, 18 and 24 h following partial hepatectomy. Consistent with findings in cultured cells stimulated to proliferate, there was an increase in chromatin molar ellipticity measured at 276 nm, and a decrease in thermal stability 3 to 8 h after surgery. These events occured prior to the onset of DNA synthesis. These early changes be­ tween non-proliferating (G0) and proliferating (G1) cells, as well as later chromatin conformational changes observed at S and G2 phases, mimic changes in template activity.Results with sheared and unsheared chromatin (both with in vitro and in vivo systems) prove that structural and functional changes can be caused by even the slightest shearing during chromatin preparation, suggesting the loss of native chromatin organization. To eliminate this problem, experiments were also conducted using chromatin in situ. A flow cytometer (FCM) was used to study unfixed liver cell suspensions stained with ethidium bromide (EB). Fluorescence was mea­ sured in the green spectral range after addition of increasing amounts of EB. Experimental evidence is provided that the same alteration in chromatin conformation can be best detected using low molar ratios of EB per unit DNA due to greater fluorescence emission in G1 respect to G0 cells.These correlated studies demonstrate that the same changes controlling chromatin organization in situ are detected also in the tertiary-quaternary structure of “isolated” chromatin. These changes in chromatin conformation are macromolecular events related to cell proliferation both at the G0 -G1 and G1 -S transitions.

Fluorescence emission and image patterning from selective photocyclic aromatization of cis–cisoid helical poly(phenylacetylene)s in situ in a film via top-down photodegradation

2018 ◽  
Vol 149 ◽  
pp. 444-448 ◽  
Author(s):  
Young-Jae Jin ◽  
Hyosang Park ◽  
Chang-Lyoul Lee ◽  
Masahiro Teraguchi ◽  
Takashi Kaneko ◽  
...  
Keyword(s):  
Fluorescence Emission ◽  
Top Down

scholarly journals An optimised method for correcting quenched fluorescence yield

2014 ◽  
Vol 11 (3) ◽  
pp. 1243-1264 ◽  
Author(s):  
L. Biermann ◽  
C. Guinet ◽  
M. Bester ◽  
A. Brierley ◽  
L. Boehme
Keyword(s):  
Light Intensity ◽  
Southern Ocean ◽  
Fluorescence Emission ◽  
Euphotic Zone ◽  
Fluorescence Yield ◽  
High Light Intensity ◽  
High Light ◽  
Photochemical Quenching ◽  
Non Photochemical Quenching

Abstract. Under high light intensity, phytoplankton protect their photosystems from bleaching through non-photochemical quenching processes. The consequence of this is suppression of fluorescence emission, which must be corrected when measuring in situ yield with fluorometers. Previously, this has been done using the limit of the mixed layer, assuming that phytoplankton are uniformly mixed from the surface to this depth. However, the assumption of homogeneity is not robust in oceanic regimes that support deep chlorophyll maxima. To account for these features, we correct from the limit of the euphotic zone, defined as the depth at which light is at ~1% of the surface value. This method was applied to fluorescence data collected by eleven animal-borne fluorometers deployed in the Southern Ocean over four austral summers. Six tags returned data showing evidence of deep chlorophyll features. Using the depth of the euphotic layer, quenching was corrected without masking subsurface fluorescence signals.

scholarly journals Laser-Induced Fluorescence Emission (L.I.F.E.) as Novel Non-Invasive Tool for In-Situ Measurements of Biomarkers in Cryospheric Habitats

10.3791/60447 ◽  
2019 ◽  
Author(s):  
Klemens Weisleitner ◽  
Lars Hunger ◽  
Christoph Kohstall ◽  
Albert Frisch ◽  
Michael C. Storrie-Lombardi ◽  
...  
Keyword(s):  
Fluorescence Emission ◽  
Laser Induced Fluorescence ◽  
In Situ Measurements ◽  
Non Invasive
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