Linked Life Data

11045723

Source:http://linkedlifedata.com/resource/pubmed/id/11045723

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2000-10-24
pubmed:abstractText
We have studied the inhibition of photosynthetic electron transport by UV-A (320-400 nm) radiation in isolated spinach thylakoids. Measurements of Photosystem II (PSII) and Photosystem I activity by Clark-type oxygen electrode demonstrated that electron flow is impaired primarily in PSII. The site and mechanism of UV-A induced damage within PSII was assessed by flash-induced oxygen and thermoluminescence (TL) measurements. The flash pattern of oxygen evolution showed an increased amount of the S0 state in the dark, which indicate a direct effect of UV-A in the water-oxidizing complex. TL measurements revealed the UV-A induced loss of PSII centers in which charge recombination between the S2 state of the water oxidizing complex and the semireduced Q(A)- and Q(B)- quinone electron acceptors occur. Flash-induced oscillation of the B TL band, originating from the S2Q(B)- recombination, showed a decreased amplitude after the second flash relative to that after the first one, which is consistent with a decrease in the amount of Q(B)- relative to Q(B) in dark adapted samples. The efficiency of UV-A light in inhibiting PSII electron transport exceeds that of visible light 45-fold on the basis of equal energy and 60-fold on the basis of equal photon number, respectively. In conclusion, our data show that UV-A radiation is highly damaging for PSII, whose electron transport is affected both at the water oxidizing complex, and the binding site of the Q(B) quinone electron acceptor in a similar way to that caused by UV-B radiation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0031-8655
pubmed:author
pubmed:issnType
Print
pubmed:volume
72
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
513-20
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Inhibition of photosynthetic electron transport by UV-A radiation targets the photosystem II complex.
pubmed:affiliation
Institute of Plant Biology, Biological Research Center, Szeged, Hungary.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't