Photoactive protochlorophyllide-enzyme complexes reconstituted with PORA, PORB and PORC proteins of A. thaliana : fluorescence and catalytic properties

Photoactive Pchlide-POR-NADPH complexes were reconstituted using protochlorophyllide (Pchlide) and recombinant light-dependent protochlorophyllide oxidoreductase (POR) proteins, His₆-PORA, His₆-PORB and His₆-PORC, from Arabidopsis thaliana. We did not observe any differences in the kinetics of the protochlorophyllide photoreduction at room temperature among the PORA, PORB and PORC proteins. In contrast, the PORC protein showed lower yield of Chlide formation than PORA and PORB when preincubated in the dark for 30 min and then illuminated for a short time. The most significant observation was that reconstituted Pchlide-POR-NADPH complexes showed fluorescence maxima at 77 K similar to those observed for highly aggregated Pchlide-POR-NADPH complexes in prolamellar bodies (PLBs) in vivo. Homology models of PORA, PORB and PORC of Arabidopsis thaliana were developed to compare predicted structures of POR isoforms. There were only slight structural differences, mainly in the organisation of helices and loops, but not in the shape of whole molecules. This is the first comparative analysis of all POR isoforms functioning at different stages of A. thaliana development

Computer modeling of rectangular-cylindrical trawl doors

Computer modeling of the rectangular-cylindrical trawl doors designed by P.P. Augulis (project 2490) is realized for calculation of their parameters to ensure stable functioning in the process of trawling. Correct choice of the warp point ensures stable functioning of the door for three ways of fastening: directly to the stringer or by means of horizontal strap or bail

Altered gene expression by sedaxane increases PSII efficiency, photosynthesis and growth and improves tolerance to drought in wheat seedlings

Succinate dehydrogenase inhibitor (SDHI) fungicides have been shown to increase PSII efficiency and photosynthesis under drought stress in the absence of disease to enhance the biomass and yield of winter wheat. However, the molecular mechanism of improved photosynthetic efficiency observed in SDHI-treated wheat has not been previously elucidated. Here we used a combination of chlorophyll fluorescence, gas exchange and gene expression analysis, to aid our understanding of the basis of the physiological responses of wheat seedlings under drought conditions to sedaxane, a novel SDHI seed treatment. We show that sedaxane increased the efficiency of PSII photochemistry, reduced non-photochemical quenching and improved the photosynthesis and biomass in wheat correlating with systemic changes in the expression of genes involved in defense, chlorophyll synthesis and cell wall modification. We applied a coexpression network-based approach using differentially expressed genes of leaves, roots and pregerminated seeds from our wheat array datasets to identify the most important hub genes, with top ranked correlation (higher gene association value and z-score) involved in cell wall expansion and strengthening, wax and pigment biosynthesis and defense. The results indicate that sedaxane confers tolerant responses of wheat plants grown under drought conditions by redirecting metabolites from defense/stress responses towards growth and adaptive development

Protochlorophyllide oxidoreductase - ligands interactions. A preliminary study.

Oksydoreduktaza protochlorofilidu (POR) przeprowadza jedną z ostatnich reakcji szlaku biosyntezy chlorofilu. Enzym ten w obecności światła katalizuje redukcję jednego z podwójnych wiązań pierścienia tetrapirolowego protochlorofilidu (Pchlidu), utleniając NADPH. W celu zbadania procesu wiązania barwnika do białka POR, opracowano model homologiczny białka PORA z Arabidopsis thialiana, a także otrzymano czyste i aktywne białko, ekspresjonowane w bakteriach Escherichia coli. Udało się odtworzyć charakterystyczny dla układów in vivo stan skompleksowania Pchlidu w postaci oligomerycznych kompleksów (Pchlid:PORA:NADPH)n bez udziału lipidów, PORB i Pchlidu b. Zaproponowano parametr określający stopień oligomeryzacji POR, którym był stosunek intensywności fluorescencji przy 660 nm do 630 nm, mierzonych przy wzbudzeniu falą o dł. 440 nm (I660/I630). W badanych warunkach, przy niedoborze barwnika względem enzymu, parametr ten był zależny liniowo od logarytmu dziesiętnego z ilorazu stężeń [Pchlid]:[POR]. Na podstawie opracowanego modelu wytypowano także reszty aminokwasowe, prawdopodobnie istotne w procesie wiązania barwnika. Otrzymano muteinę PORA-TT316/317AA, która miała niższy parametr opisujący zdolność do kompleksowania Pchlidu (I660/I630). Mutacja nie wpływała na wydajność redukcji barwnika. Na podstawie modelu i wyników eksperymentalnych zaproponowano, że reszty TT316/317, oddziałując z pierścieniem nikotynamidowym NADPH, stabilizują kieszeń wiążącą Pchlid.Protochlorophyllide oxidoreductase (POR) catalyses one of the last step of biochemical pathway of chlorophyll biosynthesis. In this light-induced reaction, one double bond of tetrapyrrole ring of protochlorophyllide (Pchlide) is reduced. During the same reaction one molecule of NADPH is oxidized. In order to analyze the process of pigment binding to POR, a homology model of PORA from Arabidopsis thaliana was obtained. Moreover, this enzyme was successfully purified from Escherichia coli expression system. It has been shown in this work, that (Pchlide:PORA:NADPH)n oligomers can be formed without lipids, Pchlide b or PORB in the reaction mixture. A new parameter – I660/I630 – which is the ratio of fluorescence intensity at 660 nm to that at 630 nm (read from the fluorescence spectrum measured for the excitation at 440nm) was proposed to describe the level of POR oligomeryzation. This parameter was linearly dependent on decimal logarithm of the [Pchlid]:[POR] ratio, for [Pchlid]:[POR] ratio < 1. Some residues of POR enzymes were suggested to be involved in Pchlide binding. The mutated protein PORA TT316/317AA was obtained. In this mutant, the pigment binding was weaker then in the wild type, but the mutation did not affect its catalytic properties. According to the homology model and the experimental data it was proposed that TT316/317 residues interact with nicotynamidic ring of NADPH and this interaction stabilizes the pigment-binding pocket

N.E.A.R (Neuropsychological Educational Approach to Remediation)

Neuropsychological Educational Approach to Remediation (N.E.A.R) is an evidenced based intervention for cognitive remediation developed by Alice Medalia, a professor atColumbiaUniversity. This intervention was developed for individuals with mental illnesses, such as schizophrenia, who experience cognitive deficits. Cognitive deficits can make it difficult for individuals to complete rehabilitation programs, receive employment and maintain independent living. N.E.A.R was developed as a computer program that consists of different activities and games that individuals complete to build memory, social skills, and problem solving skills. These games allow the individual to practice these different skills and gives frequent feedback as well as positive reinforcement. In order to receive the most benefits from N.E.A.R individuals must “bridge” or connect what they practice in N.E.A.R to the real world. Research studies have found that N.E.A.R has benefited different aspects of individuals’ lives as well as assists with the journey of recovery

Safety of Navigation During Dynamic Positioning on Mobile Water Transport Objects

This paper presents an innovation methodology for quantity assessment the safety of dynamic positioning in locally confined area of technological work performance under nonlinear dynamic disturbances of environmental factors. The methodology is based on new integrated paradigm of prediction coordinated components interactions, which form dynamic positioning system. Proposed methodology implementation effect is based on the analysis of complex models that form the knowledge base. The comprehensive reserve of controllable thruster’s reactions was adopted as quantitative characteristic of dynamic positioning safety

N.E.A.R (Neuropsychological Educational Approach to Remediation)

Neuropsychological Educational Approach to Remediation (N.E.A.R) is an evidenced based intervention for cognitive remediation developed by Alice Medalia, a professor atColumbiaUniversity. This intervention was developed for individuals with mental illnesses, such as schizophrenia, who experience cognitive deficits. Cognitive deficits can make it difficult for individuals to complete rehabilitation programs, receive employment and maintain independent living. N.E.A.R was developed as a computer program that consists of different activities and games that individuals complete to build memory, social skills, and problem solving skills. These games allow the individual to practice these different skills and gives frequent feedback as well as positive reinforcement. In order to receive the most benefits from N.E.A.R individuals must “bridge” or connect what they practice in N.E.A.R to the real world. Research studies have found that N.E.A.R has benefited different aspects of individuals’ lives as well as assists with the journey of recovery