The effects of salinity on the primary processes of photosynthesis were studied in the red alga Porphyra perforata. The results show that there are at least three sites in the photosynthetic apparatus of this alga that were affected by increased salinity. The first site, photoactivation and dark-inactivation of electron flow on the reducing side of photosystem I, was completely inhibited at hig...

We have taken a genetic approach to eliminating the presence of photosystem I (PSI) in site-directed mutants of photosystem II (PSII) in the cyanobacterium Synechocystis sp. PCC 6803. By selecting under light-activated heterotrophic conditions, we have inactivated the psaA-psaB operon encoding the PSI reaction center proteins in cells containing deletions of the three psbA genes. We have also i...

Steady-state kinetic analyses of the Photosystem II activity elicited by quinones and quinonediimines in KCN/Hg-inhibited chloroplasts reveal that: 1. Quinones generate a single reaction in which one quinone competes with another for photoreduction by Photosystem II. 2. Quinonediimines also compete with one another for photoreduction, but the electron transport activity elicited by quinonediimi...

Prochlorococcus and Synechococcus picocyanobacteria are dominant contributors to marine primary production over large areas of the ocean. Phytoplankton cells are entrained in the water column and are thus often exposed to rapid changes in irradiance within the upper mixed layer of the ocean. An upward fluctuation in irradiance can result in photosystem II photoinactivation exceeding counteracti...

Photosystem II reaction centers comprised of the Dl, D2 and cytochrome b-559 polypeptides were isolated from welldefined oxygen-evolving reaction center preparations using either a combination of LiClO, and dodecyhnaltoside, or Triton X-100 alone. Yields of chlorophyll and cytochrome b-559 for both preparative methods were compared, and pigment contents were compared based on 2.0 b-559 per reac...

Illumination of intact Bryopsis corticulans chloroplasts under anaerobic conditions induced a decline of chlorophyll fluorescence and photoinhibition of Photosystems I and II. The time course of the light-induced decline of chlorophyll fluorescence and the decreases of activities of reactions sensitized by Photosystems I and II were compared. Photosystem I activity decreased in parallel with th...

The aim of this review is to provide an up-to-date summary of the evidence surrounding glycemic index (GI) and endurance performance. Athletes are commonly instructed to consume low-GI (LGI) carbohydrate (CHO) before exercise, but this recommendation appears to be based on the results of only a few studies, whereas others have found that the GI of CHO ingested before exercise has no impact on p...

MOTIVATION A common practice in biomarker discovery is to decide whether a large laboratory experiment should be carried out based on the results of a preliminary study on a small set of specimens. Consideration of the efficacy of this approach motivates the introduction of a probabilistic measure, for whether a classifier showing promising results in a small-sample preliminary study will perfo...

the changes of chl a fluorescence induction curve in response to different salinity levels in canola (barassica napus, l.) plants were investigated. the canola seedlings were exposed to salt stress (100 mm and 200 mm nacl) for 7 days and chl a fluorescence induction kinetics was analysed. by using the ojip-test, various parameters like vj, area, n, φpo, φeo, ψo, rc/abs and piabs were calculated...