Browsing by Author "Zhang, Shuyi"

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Effect of mono-and dichromatic light quality on growth rates and photosynthetic performance of Synechococcus sp. PCC 7002
(Frontiers Research Foundation (OA), 2014) Bernstein, Hans C.; Konopka, Allan; Melnicki, Matthew R.; Hill, Eric A.; Kucek, Leo A.; Zhang, Shuyi; Shen, Gaozhong; Bryant, Donald A.; Beliaev, Alexander S.
Synechococcus sp. PCC 7002 was grown to steady state in optically thin turbidostat cultures under conditions for which light quantity and quality was systematically varied by modulating the output of narrow-band LEDs. Cells were provided photons absorbed primarily by chlorophyll (680 nm) or phycocyanin (630 nm) as the organism was subjected to four distinct mono- and dichromatic regimes. During cultivation with dichromatic light, growth rates were generally proportional to the total incident irradiance at values <275 2 μmol photons m− · s−1 and were not affected by the ratio of 630:680 nm wavelengths. Notably, under monochromatic light conditions, cultures exhibited similar growth rates only when they were irradiated with 630 nm light; cultures irradiated with only 680 nm light grew at rates that were 60–70% of those under other light quality regimes at equivalent irradiances. The functionality of photosystem II and associated processes such as maximum rate of photosynthetic electron transport, rate of cyclic electron flow, and rate of dark respiration generally increased as a function of growth rate. Nonetheless, some of the photophysiological parameters measured here displayed distinct patterns with respect to growth rate of cultures adapted to a single wavelength including phycobiliprotein content, which increased under severely light-limited growth conditions. Additionally, the ratio of photosystem II to photosystem I increased ∼40% over the range of growth rates, although cells grown with 680 nm light only had the highest ratios. These results suggest the presence of effective mechanisms which allow acclimation of Synechococcus sp. PCC 7002 acclimation to different irradiance conditions.
Extensive remodeling of a cyanobacterial photosynthetic apparatus in far-red light
(American Association for the Advancement of Science, 2014-08) Gan, Fei; Zhang, Shuyi; Rockwell, Nathan C.; Martin, Shelley; Langarias, J. Clark; Bryant, Donald A.; Gan, Fei; Zhang, Shuyi; Rockwell, Nathan C.; Martin, Shelley; Langarias, J. Clark; Bryant, Donald A.
Cyanobacteria are unique among bacteria in performing oxygenic photosynthesis, often together with nitrogen fixation and, thus, are major primary producers in many ecosystems. The cyanobacterium, Leptolyngbya sp. strain JSC-1, exhibits an extensive photoacclimative response to growth in far-red light that includes the synthesis of chlorophylls d and f. During far-red acclimation, transcript levels increase ≥2-fold for ~900 genes and decrease ≥2-fold for ~2000 genes. Core subunits of photosystem I, photosystem II, and phycobilisomes are replaced by proteins encoded in a 21-gene cluster that includes a knotless red/far-red phytochrome and two response regulators. This acclimative response enhances light harvesting for wavelengths complementary to the growth light (λ = 700 to 750 nm) and enhances oxygen evolution in far-red light.
Tables S1 and S2 [dataset]
(2014-08) Gan, Fei; Zhang, Shuyi; Rockwell, Nathan C.; Martin, Shelley; Langarias, J. Clark; Bryant, Donald A.
This dataset is associated with the following article: Gan, F., S. Zhang, N. C. Rockwell, S. S. Martin, J. C. Lagarias, and D. A. Bryant. “Extensive Remodeling of a Cyanobacterial Photosynthetic Apparatus in Far-Red Light." Science 345, no. 6202 (August 21, 2014): 1312-1317. doi:10.1126/science.1256963