22 research outputs found
Physiological and structural adjustments of two ecotypes of Platanus orientalis L. from different habitats in response to drought and re-watering
No full textPlatanus orientalis covers a very fragmented area in Europe and, at the edge of its natural distribution, is considered a relic endangered species near extinction. In our study, it was hypothesized that individuals from the edge of the habitat, with stronger climate constrains (drier and warmer environment, Italy, IT ecotype), developed different mechanisms of adaptation than those growing under optimal conditions at the center of the habitat (more humid and colder environment, Bulgaria, BG ecotype). Indeed, the two P. orientalis ecotypes displayed physiological, structural and functional differences already under control (unstressed) conditions. Adaptation to a dry environment stimulated constitutive isoprene emission, determined active stomatal behavior, and modified chloroplast ultrastructure, ultimately allowing more effective use of absorbed light energy for photochemistry. When exposed to short-term acute drought stress, IT plants showed active stomatal control that enhanced instantaneous water use efficiency, and stimulation of isoprene emission that sustained photochemistry and reduced oxidative damages to membranes, as compared to BG plants. None of the P. orientalis ecotypes recovered completely from drought stress after re-watering, confirming the sensitivity of this mesophyte to drought. Nevertheless, the IT ecotype showed less damage and better stability at the level of chloroplast membrane parameters when compared to the BG ecotype, which we interpret as possible adaptation to hostile environments and improved capacity to cope with future, likely more recurrent, drought stress
Redesign of the Chlamydomonas reinhardtii Q<sub>B</sub> binding niche reveals photosynthesis works in the absence of a driving force for Q<sub>A</sub>-Q<sub>B</sub> electron transfer
No full textAn in silico redesign of the secondary quinone electron acceptor (QB) binding pocket of the D1 protein of Photosystem II (PSII) suggested that mutations of the F265 residue would affect atrazine binding. Chlamydomonas reinhardtii mutants F265T and F265S were produced to obtain atrazine-hypersensitive strains for biosensor applications, and the mutants were indeed found to be more atrazine-sensitive than the reference strain IL. Fluorescence and thermoluminescence data agree with a weak driving force and confirm slow electron transfer but cannot exclude an additional effect on protonation of the secondary quinone. Both mutants grow autotrophically, indicating that PSII requires strong light for optimal function, as was the case in the ancestral homodimeric reaction center.</p
Comparative study of the smoke emissions from fine-cut tobacco blends depending on the characteristics of the used RYO/MYO cigarette materials
No full textThe European tobacco market has experienced significant changes in the last years – with the introduction of new tobacco products and the increased consumption of certain traditional products. Recent research of fine-cut tobacco blends (for RYO and MYO cigarettes) in Bulgaria is very limited, which substantiates the current comparative investigation of the smoke emissions of RYO tobaccos, accounting for the used materials (cigarette paper and filter tips). Three variants of laboratory-made cigarettes from five tobacco blends (A -E) were analyzed: variant I – with ready-to-use cigarette tubes; variant II – with gummed cigarette paper and filter tips with diameter 8 mm and length 15 mm; variant III – with the same cigarette paper and filter tips with diameter 6 mm and length 20 mm. The highest levels of smoke emissions were found for variant I and the minimal -for variant III, with no uniform trend between the blends. The smoke emissions from the analyzed RYO tobaccos exceeded the legal limits for commercial cigarettes, except for nicotine from blends B and D, and CO from blend D in variant III. In all variants, a strong correlation between the studied smoke emissions was observed -positive for nicotine/tar and tar/CO, and negative for nicotine/CO
Increased thermostability of thylakoid membranes in isoprene-emitting leaves probed with three biophysical techniques
No full textThree biophysical approaches were used to get insight into increased thermostability of thylakoid membranes in isoprene-emittingplants.Arabidopsis (Arabidopsis thaliana) plants genetically modified to make isoprene and Platanus orientalis leaves, in which isoprene emission was chemically inhibited, were used. First, in the circular dichroism spectrum the transition temperature of the main band at 694 nm was higher in the presence of isoprene, indicating that the heat stability of chiral macrodomains of chloroplast membranes, and specifically the stability of ordered arrays of light-harvesting complex IIphotosystem II in the stacked region of the thylakoid grana, was improved in the presence of isoprene. Second, the decay of electrochromic absorbance changes resulting from the electric field component of the proton motive force (ΔA 515) was evaluated following single-turnover saturating flashes. The decay of ΔA 515 was faster in the absence of isoprene when leaves of Arabidopsis and Platanus were exposed to high temperature, indicating that isoprene protects the thylakoid membranes against leakiness at elevated temperature. Finally, thermoluminescence measurements revealed that S 2Q B 2 charge recombination was shifted to higher temperature in Arabidopsis and Platanus plants in the presence of isoprene, indicating higher activation energy for S 2Q B 2 redox pair, which enables isoprene-emitting plants to perform efficient primary photochemistry of photosystem II even at higher temperatures. The data provide biophysical evidence that isoprene improves the integrity and functionality of the thylakoid membranes at high temperature. These results contribute to our understanding of isoprene mechanism of action in plant protection against environmental stresses. © 2011 American Society of Plant Biologists. All Rights Reserved
Isoprene emission in the monocot Arundineae tribe in relation to functional and structural organization of the photosynthetic apparatus
No full textSeveral plant species emit isoprene, a compound able to protect plants against high temperatures and oxidative stresses, and to affect the oxidative capacity of the atmosphere. The emission of isoprene in monocots is much less investigated than in dicots. We explored the emission of isoprene among members of the Poaceae tribe Arundineae, and its potential impact on plant performance. Our results confirm, also in monocots, the existence of a significant correlation between photosynthesis and isoprene emission and further suggest that isoprene inversely correlates to habitat xericity in unstressed Arundineae. Isoprene emission capacity developed rapidly in unfolding leaves, implying some developmental differences in the control of this biosynthetic pathway with respect to dicots. Among Arundineae, marked species-specific differences in several parameters related to plant productivity (photosynthesis, carbon lost as isoprene, water use efficiency, biomass and chloroplast ulrastructure) were observed. Isoprene presence improved structural organization of thylakoid membrane system and decreased the heat dissipation at physiological temperature. Our results demonstrate that, as in dicots, also in monocots isoprene could contribute to improve photosynthesis performance, although this was not necessarily reflected in higher yields, at least in unstressed condition
Microbiome status of unregulated raw tobacco blends for hand-rolling cigarettes (RYO tobaccos)
No full textThe research was conducted on 18 samples of RYO tobacco. The density (CFU/g a.d.s.) of three heterotrophic groups of microorganisms and some physical-chemical indicators were determined. The analyses were performed according to classic methods. Quantitative and qualitative changes at the microbiome as a result of disruption of homeostasis in microbial communities and development of secondary succession in the direction of intensive mineralization processes were found. Statistically significant correlation dependences with the physical-chemical parameters were registered. In addition to a potential risk in term of sanitary-hygiene and health aspects, the changes also have a negative impact on the consumer qualities of tobacco blends
Analysis of research results of physical development in children aged 5-6 years in Stara Zagora Municipality - Bulgaria
No full textMicrobiome status of unregulated raw tobacco blends for hand-rolling cigarettes (RYO tobaccos)
No full textThe research was conducted on 18 samples of RYO tobacco. The density (CFU/g a.d.s.) of three heterotrophic groups of microorganisms and some physical-chemical indicators were determined. The analyses were performed according to classic methods. Quantitative and qualitative changes at the microbiome as a result of disruption of homeostasis in microbial communities and development of secondary succession in the direction of intensive mineralization processes were found. Statistically significant correlation dependences with the physical-chemical parameters were registered. In addition to a potential risk in term of sanitary-hygiene and health aspects, the changes also have a negative impact on the consumer qualities of tobacco blends
Assessment of heavy metal levels in roll-your-own cigarette and water pipe tobacco blends
No full textThe increased consumption of roll-your-own (RYO) cigarettes and water pipe (hookah), both globally and in Bulgaria, necessitated the current investigation aimed at the assessment of heavy metal levels in the tobacco blends used in those products. The concentrations of Mn, Zn, Cu, Cd, Pb, and Ni were determined by AAS in five brands of RYO tobacco (R1-R5) and seven brands of water pipe tobacco (W1- W7), all distributed on Bulgarian market. The average heavy metal contents (mg/kg) in the two types of tobacco blends, RYO and water pipe, respectively, were as follows: Mn - 214.20 and 37.89; Zn - 31.90 and 134.87; Cu - 12.06 and 10.07; Cd - 0.80 and 1.33; Pb - 1.60 and 3.57; Ni - 1.36 and 0.80. RYO cigarette tobaccos contained higher concentration of Mn, Cu and Ni, while water pipe tobaccos - Zn, Cd and Pb. Strong correlations were found between Cu and Zn (r=0.81), Cu and Cd (r=0.90) in RYO tobacco blends, and between Cu and Zn (r=0.86) - in water pipe blends, respectively. The results from the study give reason to recommend that this information be provided to the consumers, who consider the regarded tobacco products as a safer alternative to conventional cigarettes
Assessment of heavy metal levels in roll-your-own cigarette and water pipe tobacco blends
No full textThe increased consumption of roll-your-own (RYO) cigarettes and water pipe (hookah), both globally and in Bulgaria, necessitated the current investigation aimed at the assessment of heavy metal levels in the tobacco blends used in those products. The concentrations of Mn, Zn, Cu, Cd, Pb, and Ni were determined by AAS in five brands of RYO tobacco (R1-R5) and seven brands of water pipe tobacco (W1- W7), all distributed on Bulgarian market. The average heavy metal contents (mg/kg) in the two types of tobacco blends, RYO and water pipe, respectively, were as follows: Mn - 214.20 and 37.89; Zn - 31.90 and 134.87; Cu - 12.06 and 10.07; Cd - 0.80 and 1.33; Pb - 1.60 and 3.57; Ni - 1.36 and 0.80. RYO cigarette tobaccos contained higher concentration of Mn, Cu and Ni, while water pipe tobaccos - Zn, Cd and Pb. Strong correlations were found between Cu and Zn (r=0.81), Cu and Cd (r=0.90) in RYO tobacco blends, and between Cu and Zn (r=0.86) - in water pipe blends, respectively. The results from the study give reason to recommend that this information be provided to the consumers, who consider the regarded tobacco products as a safer alternative to conventional cigarettes
