جستجوی مقالات مرتبط با کلیدواژه « فتوسنتز » در نشریات گروه « علوم »

The present paper attempts to provide an introduction to the new and fascinating science of quantum biology. One of the major challenges in this field is the ambiguity of the concept of quantum biology which simply means the application of quantum mechanics to biological issues or critical processes. Quantum biology is essentially a new interdisciplinary science of quantum mechanics, chemistry, physics, biochemistry and biology. Quantum biology demonstrates biological phenomena that explicitly apply quantum mechanics to gain or perform a particular action. They have been observed in the biological world, explaining the existence and effect of these phenomena on important biological processes such as photosynthesis and enzymatic catalysis. It also deals with the role of quantum mechanics in other biological topics such as bird orientation, olfaction, vision, consciousness and the beginning of life. Finally, the Quantum Biology Research Core (QBRC-IBB) hosted at Institute of Biochemistry and Biophysics (IBB), University of Tehran is mentioned.

Climate change caused by greenhouse gases by producing more than 80 percent of the global energy from fossil fuels, which is associated with a large amount of greenhouse gases, regulations and limitations on nonrenewable fossil fuels consumptions, and exponential increase in energy demand are the major challenges for today’s industrial communities. The consumption rate of nitrogenous nutrients is higher than the population growth. Moreover, one to two percent of the energy consumption and three to five percent of the natural gas production in the world are allocated to the Haber-Bosch process to produce ammonia being the only nitrogenous nutrient source in agriculture. Furthermore, limitations and decreases in sweet water resources along with the increases in population and global warming are serious concerns and challenges. The source of all these challenges lie in the molecules found in nature that make up the important processes of the lifecycle and of photosynthesis, such as water, methane, carbon dioxide, ammonia, oxygen, nitrogen and hydrogen. In this work, research and technology-based approaches and strategies have been presented to overcome these challenges in the future by introducing the standing and role of each of these seven crucial molecules that affect the above challenges.

Oil pollutions as a consequence of increasing consumption of petroleum، have a tremendous effect on water and soil ecosystems and their microflora. In this study the diversity in physiological parameters، including growth rate، photosynthesis، chlorophyll-a and phycobiliproteins content، between cyanobacterial strains flora isolated from oil-polluted and non-polluted areas، were assessed. To this end، strains were isolated and purified. The experiments were carried out on logarithmic phase cultures of the isolates in suitable liquid media. The chlorophyll and phycobiliproteins contents were determined using a colorimetric method. Photosynthesis was measured by Oxyview apparatus. Growth rates were calculated based on dry weights. Under laboratory conditions، the photosynthesis activity and the chlorophyll content of isolates from oil-polluted sites were significantly lower than non-polluted isolates. On the other hand، the growth rate average of strains from oil-polluted sites was significantly higher than non-polluted strains. Also despite the higher phycobiliproteins content in non-polluted isolates، there was no significant difference in any of these pigments between the two groups. Altogether the results showed that in response to petroleum stress، the cyanobacteria restore the decrease in their chlorophyll content and photosynthesis activity by increasing their biomass. In fact the response is the reflects of restructuring cyanobacterial flora from sensitive autotrophic species to oil-pollution resistant mixotrophic species in the polluted ecosystems that in addition to photosynthesis are able to use crude oil as an energy source for their growth requirements، hence overcome the energy loss due to reduction of photosynthesis and even increase growth rate than non-oil-pollution isolates.

Effect of boron deficiency on growth, leaf pigments and photosynthesis was studied in turnip (Brassica rapa L.) plants grown under three different light conditions (50, 100 and 150 µmol m-2 s-1) in a hydroponic medium for one month under controlled environmental conditions. Two levels of B treatment including adequate (25 µM) and low (2.5 µM) boron supply were applied. Dry matter production of shoot and root was reduced under low boron supply up to 79% and 82% respectively. Re-supply of deficient plants by boron during the last week of growth period increased significantly plants dry matter production. Higher light conditions increased not only plants growth but also boron uptake. Plants susceptibility to low boron supply was higher under high compared with lower light conditions. Leaf chlorophyll and carotenoids decreased under boron deficiency conditions while leaf anthocyanins and free soluble phenolics in leaf and roots increased in low boron plants.

Due to the importance of benthic cyanobacteria in nitrogen fixation in paddyfields, the physiological responses of Fischerella ambigua FS 18 to salinity (NaCl 0, 0.5 & 1%) were investigated. Results indicated that growth rate was higher in control and that NaCl did not inhibit growth of other treatments. Similar responses were seen in the case of other physiological processes. Chlorophyll was declined with increasing salinity. Phycobiliproteins (PBP), phycocyanin (PC) and allophycocyanin (APC) were at least in 0.5% but the differences were not significant. The light-saturated photosynthetic rate was higher in control and decreased with increasing in salinity. With respect to nitrogenase activity, the highest rate was in control and the cultures with higher growth rates reached to the maximum level at a shorter time. There was no significant difference between 0.5 and 1% in relation to nitrogenase activity.