Disease relevance of Photosynthesis

• To explore how energy-generating processes of the Synechococcus ecotypes track natural light and O2 conditions, we evaluated accumulation of transcripts encoding proteins involved in photosynthesis, respiration, and fermentation [1].
• Some cyanobacteria couple oxygenic photosynthesis in vegetative cells with O2-sensitive N2 fixation in differentiated cells called heterocysts [2].
• Growth and photosynthetic characteristics of a selected mutant strain under photoautotrophic conditions were similar to those of the wild type, suggesting that the function of PsaL is dispensable for photosynthesis in Synechocystis sp. PCC 6803 [3].
• Previous genetic analysis indicated that the photosynthesis gene cluster from Rhodobacter capsulatus coded for the transcription factor, CrtJ, that is responsible for aerobic repression of bacteriochlorophyll, carotenoid, and light harvesting-II gene expression [4].
• Nuclear extracts from maize leaves have been shown previously to contain a factor, MNF1, that interacts with both the cauliflower mosaic virus 35S promoter and the promoter of the maize gene for phosphoenolpyruvate carboxylase, which is involved in C4 photosynthesis [5].

High impact information on Photosynthesis

• Photosystem II (PSII) is a key component of photosynthesis, the process of converting sunlight into the chemical energy of life [6].
• These biochemical characteristics of C4 photosynthesis in cells around the vascular bundles of stems of C3 plants might explain why C4 photosynthesis has evolved independently many times [7].
• Characteristics of C4 photosynthesis in stems and petioles of C3 flowering plants [7].
• This approach depends on accurate estimates of the carbon isotopic discrimination of terrestrial photosynthesis (Delta; ref. 5) at large regional scales, yet terrestrial ecosystem heterogeneity makes such estimates problematic [8].
• Structures resembling remarkably preserved bacterial and cyanobacterial microfossils from about 3,465-million-year-old Apex cherts of the Warrawoona Group in Western Australia currently provide the oldest morphological evidence for life on Earth and have been taken to support an early beginning for oxygen-producing photosynthesis [9].

Chemical compound and disease context of Photosynthesis

• A bacterial homolog of the mammalian mitochondrial benzodiazepine receptor, the tryptophan-rich sensory protein (TspO) has been previously demonstrated to negatively affect the transcriptional expression of several photosynthesis genes of Rhodobacter sphaeroides [10].
• Thus, UV light intensity and efficiency of epidermal vitamin D3 photosynthesis may contribute to geographic and racial variability in blood pressure and the prevalence of hypertension [11].
• The filamentous non-heterocystous cyanobacterium Plectonema boryanum fixes dinitrogen at a high rate during microaerobic growth in continuous illumination by temporal separation of oxygen-evolving photosynthesis and oxygen-sensitive dinitrogen fixation [12].
• Phosphatidylglycerol (PG), a ubiquitous constituent of thylakoid membranes of chloroplasts and cyanobacteria, is demonstrated to be essential for the functionality of plastoquinone electron acceptor Q(B) in the photosystem II reaction center of oxygenic photosynthesis [13].
• Mutation of Phe-363 in the photosystem II protein CP47 impairs photoautotrophic growth, alters the chloride requirement, and prevents photosynthesis in the absence of either PSII-O or PSII-V in Synechocystis sp. PCC 6803 [14].

Biological context of Photosynthesis

• Here we report the first biophysical evidence demonstrating that aerobic bacterial photosynthesis is widespread in tropical surface waters of the eastern Pacific Ocean and in temperate coastal waters of the northwestern Atlantic. Our results indicate that these organisms account for 2-5% of the photosynthetic electron transport in the upper ocean [15].
• These photosynthetic cells possess high activities of enzymes characteristic of C4 photosynthesis, which allow the decarboxylation of four-carbon organic acids from the xylem and phloem, thus releasing CO2 for photosynthesis [7].
• Increased iron supply led to elevated phytoplankton biomass and rates of photosynthesis in surface waters, causing a large drawdown of carbon dioxide and macronutrients, and elevated dimethyl sulphide levels after 13 days [16].
• Here we review evidence for an important role of LGT in the evolution of photosynthesis, aerobic respiration, nitrogen fixation, sulfate reduction, methylotrophy, isoprenoid biosynthesis, quorum sensing, flotation (gas vesicles), thermophily, and halophily [17].
• We present evidence that hexokinase is involved in sensing endogenous levels of sugars in photosynthetic tissues and that it participates in the regulation of senescence, photosynthesis, and growth in seedlings as well as in mature plants [18].

Anatomical context of Photosynthesis

• (ii) Transcripts of the rpo genes and of rps15, but not of genes involved in photosynthesis and related processes (psbA, rbcL, atpI-H), were abundantly accumulated in ribosome-deficient plastids [19].
• The pathogen adheres to a beta-galactoside-containing receptor in the coral mucus, penetrates into epithelial cells, differentiates into a viable-but-not-culturable form, multiplies, and produces a proline-rich peptide toxin that inhibits photosynthesis of the zooxanthellae in the presence of ammonia [20].
• In the present study, we examined the effects of the transformation of tobacco plants with cDNA for glycerol-3-phosphate acyltransferase from squash on the unsaturation of fatty acids in thylakoid membrane lipids and the response of photosynthesis to various temperatures [21].
• These results suggest that reduction of extracellular ferricyanide (mediated at the plasma membrane) interacts with both photosynthesis and respiration, and that both of these processes contribute NADPH in the light [22].
• The time required for recovery of photosynthesis from inhibition during persistent CO2 stress was similar to the time required for establishing steady-state pH values in the cytosol under acid stress [23].

Associations of Photosynthesis with chemical compounds

• Kranz anatomy is not essential for terrestrial C4 plant photosynthesis [24].
• One implication of this limitation is that a larger iron supply to the region in glacial times could have stimulated algal photosynthesis, leading to lower concentrations of atmospheric CO2 [25].
• We suggest that anoxygenic photosynthesis is a relatively recent phenomenon in the Black Sea initiated by shallowing of the chemocline over the past decade and development of an anoxic layer devoid of O2 and H2S [26].
• In their model, atmospheric CO2 falls below the critical level for C3 photosynthesis, 150 parts per million (p.p.m.), in only 100 Myr, and this is assumed to mark the demise of the biosphere as a whole [27].
• RuBisCO, D-ribulose-1,5-bisphosphate carboxylase-oxygenase (EC 4.1.1.39), converts carbon dioxide to sugar in the first step of photosynthesis [28].

Gene context of Photosynthesis

• Here we show that the gene encoding PsbS, an intrinsic chlorophyll-binding protein of photosystem II, is necessary for nonphotochemical quenching but not for efficient light harvesting and photosynthesis [29].
• Light acts both directly as a signal and indirectly through photosynthesis to regulate the expression of genes encoding nitrate reductase (NR) [30].
• The growth and photosynthesis of dgd1 dgd2 were affected more severely compared with those of dgd1, indicating that the residual amount of DGDG in dgd1 is crucial for normal plant development [31].
• The high-chlorophyll fluorescence photosynthesis mutant hcf109 of Arabidopsis was characterized in detail to gain insights into the regulatory mechanism of RNA processing in higher plants [32].
• During photo-oxidative stress, chlorophyll content and photosynthetic quantum yield were slightly reduced in vte1 as compared with wild type indicating a potential role for tocopherol in maintaining an optimal photosynthesis rate under high-light stress [33].

Analytical, diagnostic and therapeutic context of Photosynthesis

• Stomata form pores on leaf surfaces that regulate the uptake of CO2 for photosynthesis and the loss of water vapour during transpiration [34].
• Level of glutathione is regulated by ATP-dependent ligation of glutamate and cysteine through photosynthesis in Arabidopsis thaliana: mechanism of strong interaction of light intensity with flowering [35].
• Net photosynthesis (PN) was measured in the control (water-sprayed) and pesticide-treated plants, 1, 3 and 7 days after treatment, with a LICOR 6200 Portable Photosynthesis System. The pesticide-treated plants showed a significant reduction (24% with malathion and 20% with carbaryl) in PN after the first application [36].
• Titration with DCMU decreased the rate of photosynthesis and increased P700 flux [37].
• The degradation experiment was performed under controlled laboratory conditions and accompanied by chemical analyses by GC/GC-MS, molecular analyses by PCR and DGGE as well as functional analyses by microsensor measurements of oxygen, photosynthesis, sulfide, pH and light [38].

References