scholarly journals A long-term chromatic adaptation mechanism

2002 ◽  
Vol 2 (10) ◽  
pp. 31-31 ◽  
Author(s):  
P. B. Delahunt ◽  
M. A. Webster ◽  
L. Ma ◽  
J. S. Werner
Keyword(s):  
Chromatic Adaptation ◽  
Adaptation Mechanism

scholarly journals Tolerance of Facultative Metallophyte Carlina acaulis to Cadmium Relies on Chelating and Antioxidative Metabolites

2020 ◽  
Vol 21 (8) ◽  
pp. 2828 ◽  
Author(s):  
Sławomir Dresler ◽  
Maciej Strzemski ◽  
Jozef Kováčik ◽  
Jan Sawicki ◽  
Michał Staniak ◽  
...  
Keyword(s):  
Cadmium Stress ◽  
Shoot Biomass ◽  
Short Term ◽  
Adaptation Mechanism ◽  
Cd Accumulation ◽  
Hormetic Effect ◽  
Antioxidative Metabolites ◽  
The Impact ◽  
Anatomical Adaptation

The impact of long-term chronic cadmium stress (ChS, 0.1 µM Cd, 85 days) or short-term acute cadmium stress (AS, 10 µM Cd, 4 days) on Carlina acaulis (Asteraceae) metabolites was compared to identify specific traits. The content of Cd was higher under AS in all organs in comparison with ChS (130 vs. 16 µg·g−1 DW, 7.9 vs. 3.2 µg·g−1 DW, and 11.5 vs. 2.4 µg·g−1 DW in roots, leaves, and trichomes, respectively) while shoot bioaccumulation factor under ChS (ca. 280) indicates efficient Cd accumulation. High content of Cd in the trichomes from the AS treatment may be an anatomical adaptation mechanism. ChS evoked an increase in root biomass (hormesis), while the impact on shoot biomass was not significant in any treatment. The amounts of ascorbic acid and sum of phytochelatins were higher in the shoots but organic (malic and citric) acids dominated in the roots of plants from the ChS treatment. Chlorogenic acid, but not ursolic and oleanolic acids, was elevated by ChS. These data indicate that both chelation and enhancement of antioxidative power contribute to protection of plants exposed to long-term (chronic) Cd presence with subsequent hormetic effect.

Luminance-dependent long-term chromatic adaptation

2016 ◽  
Vol 33 (3) ◽  
pp. A164 ◽  
Author(s):  
Joris Vincent ◽  
Alex M. Kale ◽  
Steven L. Buck
Keyword(s):  
Chromatic Adaptation

Very-long-term chromatic adaptation: Test of gain theory and a new method

2008 ◽  
Vol 25 (3) ◽  
pp. 411-414 ◽  
Author(s):  
SUZANNE C. BELMORE ◽  
STEVEN K. SHEVELL
Keyword(s):  
New Method ◽  
Chromatic Adaptation ◽  
Adaptation Period ◽  
Ambient Illumination ◽  
Long Wavelength ◽  
Room Illumination ◽  
Light Levels ◽  
Test Light ◽  
Adaptation Test

This research had two goals. First, a new method of very-long-term chromatic adaptation was compared to an older method of long-wavelength ambient illumination. In the new method, the observer viewed for 1 h per day for 12 or 14 days a CRT screen composed of oriented lines that appeared red. One observer also replicated a previous procedure (Neitz et al., 2002) in which she was exposed to long-wavelength room illumination for 4 h per day for 14 days. For both methods, equilibrium yellow was measured each day about 20 h after the end of the adaptation period. Both methods of very-long-term chromatic adaptation gave similar results. Second, shifts in equilibrium yellow were measured over a 30:1 range of light levels to determine if changes in color percepts were explained solely by a gain change in cone sensitivities (von Kries coefficient law). The magnitude of shift of equilibrium yellow depended on the level of the test light, which was not consistent with a gain theory of very-long-term chromatic adaptation.

scholarly journals Natural Scenes are a Possible Source of Luminance-dependent Long-term Chromatic Adaptation

2016 ◽  
Vol 16 (4) ◽  
pp. 28
Author(s):  
Alex Kale ◽  
Joris Vincent ◽  
Steven L. Buck
Keyword(s):  
Chromatic Adaptation ◽  
Natural Scenes

scholarly journals Grazing Sheep in Organic Vineyards: An On-Farm Study about Risk of Chronic Copper Poisoning

2021 ◽  
Vol 13 (22) ◽  
pp. 12860
Author(s):  
Martin Trouillard ◽  
Amélie Lèbre ◽  
Felix Heckendorn
Keyword(s):  
Experimental Period ◽  
Copper Accumulation ◽  
Agricultural Practice ◽  
Protective Mechanisms ◽  
Adaptation Mechanism ◽  
Chronic Poisoning ◽  
Winter Grazing ◽  
Grazing Period ◽  
On Farm

Many winegrowers and sheep breeders are interested in wintertime grazing in vineyards, as an agroecological alternative to mowing or herbicide spraying, and additional supply of forage. Still, strong concern is raised by the use of copper-based fungicides, particularly in organic vineyards, since copper is known to induce chronic toxicosis in sheep. We conducted an on-farm study with n = 12 1-year-old Merinos × Mourerous ewes grazing the cover vegetation of vineyard plots during wintertime, in order to check whether this agricultural practice might be harmful to sheep. Our results indicate that most copper found in the cover vegetation originates from fungicide spraying versus plant uptake from the soil, and that rain-induced washing-off and plant growth-triggered dilution of copper are crucial to reach close-to-safe grazing conditions. Furthermore, we found that while sheep remained globally healthy during the 2 months of the experimental period, the plasma activity of Glutamate Dehydrogenase increased by 17.3 ± 3.0 U/L upon vineyard grazing (p < 0.001), reflecting liver storage of copper. We also discovered that the dynamics of molybdenum in sheep plasma are strongly affected by exposure to copper, suggesting a possible adaptation mechanism. Overall, our results suggest that winter grazing of sheep in organic vineyards is reasonably safe, but that care should be taken about grazing period duration. More research should be conducted with respect to long-term copper accumulation, spring and summer grazing, and possible protective mechanisms against copper chronic poisoning.

scholarly journals Photoautotrophic picoplankton – a review on their occurrence, role and diversity in Lake Balaton

2020 ◽  
Vol 71 (4) ◽  
pp. 371-382 ◽  
Author(s):  
Boglárka Somogyi ◽  
Tamás Felföldi ◽  
László G. Tóth ◽  
Gábor Bernát ◽  
Lajos Vörös
Keyword(s):  
Single Cells ◽  
Light Availability ◽  
Grazing Pressure ◽  
Chromatic Adaptation ◽  
Lake Balaton ◽  
The Past ◽  
Level 1 ◽  
Dynamic Community ◽  
Temperature Optima

AbstractOccurrence of the smallest phototrophic microorganisms (photoautotrophic picoplankton, APP) in Lake Balaton was discovered in the early 1980s. This triggered a series of systematic studies on APP and resulted in the setting of a unique long-term picoplankton dataset. In this review, we intend to summarize the obtained results and to give a new insight on APP ecology and diversity in Lake Balaton. According to the results, APP dynamics depends on trophic state, temperature, nutrient, and light availability, as well as grazing pressure. APP abundance in Lake Balaton decreased to a low level (1–2 × 105 cells mL−1) as a consequence of decreasing nutrient supply (oligotrophication) during the past more than two decades, and followed a characteristic seasonal dynamics with higher abundance values from spring to autumn than in winter. Concomitantly, however, the APP contribution to both phytoplankton biomass and primary production increased (up to 70% and 40–50%, respectively) during oligotrophication. Regarding annual pattern, picocyanobacteria are dominant from spring to autumn, while in winter, picoeukaryotes are the most abundant, most likely due to the different light and temperature optima of these groups. Within picocyanobacteria, single cells and microcolonies were both observed with mid-summer dominance of the latter which correlated well with the density of cladocerans. Community-level chromatic adaptation (i.e., dominance of phycoerythrin- or phycocyanin-rich forms) of planktonic picocyanobacteria was also found as a function of underwater light quality. Sequence analysis studies of APP in Lake Balaton revealed that both picocyanobacteria and picoeukaryotes represent a diverse and dynamic community consisting several freshwater genotypes (picocyanobacteria: Synechococcus, Cyanobium; picoeukaryotes: Choricystis, Stichococcus, Mychonastes, Nannochloris, and Nannochloropsis).

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