Photosynthetic response mechanism to polybrominated diphenyl ether exposure in Chlorella pyrenoidosa.

Polybrominated diphenyl ether (PBDE) contamination is common in aquatic environments and can severely damage aquatic organisms. However, there is a lack of information on the response and self-adaptation mechanisms of these organisms. Chlorella pyrenoidosa was treated with 2,2',4,4'-tetrabromodiphenyl ether (BDE47), causing significant growth inhibition, pigment reduction, oxidative stress, and chloroplast atrophy. Photosynthetic damage contributed to inhibition, as indicated by Fv/Fm, Chl a fluorescence induction, photosynthetic oxygen evolution activity, and photosystem subunit stoichiometry. Here, Chl a fluorescence induction and quinone electron acceptor (QA-) reoxidation kinetics showed that the PSII donor and acceptor sides were insensitive to BDE47. Quantitative analyses of D1 and PsaD proteins illustrated that PSII and PSI complexes were the main primary targets of photosynthesis inhibition by BDE47. Significant modulation of PSII complex might have been caused by the potential binding of BDE47 on D1 protein, and molecular docking was performed to investigate this. Increased activation of antioxidant defense systems and photosystem repair as a function of exposure time indicated a positive resistance to BDE47. After a 5-day exposure, 23 % of BDE47 was metabolized. Our findings suggest that C. pyrenoidosa has potential as a bioremediator for wastewater-borne PBDEs and can improve our understanding of ecological risks to microalgae.

Distortion Prediction in Inconel-718 Part Fabricated through LPBF by Using Homogenized Support Properties from Experiments and Numerical Simulation.

The Laser Powder-Bed Fusion (LPBF) process produces complex part geometry by selectively sintering powder metal layer upon layer. During the LPBF process, parts experience the challenge of residual stress, distortions, and print failures. Lattice-based structures are used to support overhang parts and reduce distortion; this lattice support has complex geometry and demands high computational effort to predict distortion using simulation. This study proposes a computational efforts reduction strategy by replacing complex lattice support geometry with homogenization using experimentally determined mechanical properties. Many homogenization models have been established to relate the lattice topology and material properties to the observed mechanical properties, like the Gibson-Ashby model. However, these predicted properties vary from as printed lattice geometry. In this work, the power-law relationship of mechanical properties for additively manufactured Inconel 718 part is obtained using tensile tests of various lattice support topologies and the model is used for homogenization in simulation. The model's accuracy in predicting distortion in printed parts is demonstrated using simulation results for a cantilever model. Simulation studies show that computational speed is significantly increased (6-7 times) using the homogenization technique without compromising the accuracy of distortion prediction.

Metabolic Engineering of Isoflavonoid Biosynthesis by Expressing Glycine max Isoflavone Synthase in Allium cepa L. for Genistein Production.

Isoflavonoids, the diverse group of secondary metabolites derived from the phenylpropanoid pathway, are distributed predominantly in leguminous plants and play a vital role in promoting human health. Genetic engineering of the metabolite synthesis pathway has turned out to be an attractive approach for the production of various secondary metabolites. In our study, we attempted to produce the isoflavone genistein, a well-known health-promoting metabolite, in Allium cepa L. (onion) by introducing Glycine max Isoflavone synthase (GmIFS). The GmIFS gene was cloned into the pEarleyGate 102 HA vector and transformed into onion by Agrobacterium-mediated and biolistic methods. The presence of GmIFS in transgenic onion was confirmed by PCR, dot blot, and Southern hybridization. Analysis of the transgenic onion calli lines demonstrated that the expression of the GmIFS gene led to the production of isoflavone genistein in in vitro tissues. The biolistic stable transformed calli with transformation efficiency of 73% (62.65 nM/g FW) accumulated more genistein than the Agrobacterium stable transformed calli with transformation efficiency of 56% (42.5 nM/g FW). Overall, heterologous gene expression of GmIFS was demonstrated by modifying the secondary metabolite pathway in onion tissues for the production of isoflavone genistein that can boost up human health with its health-promoting properties.

Cadmium induced physio-biochemical and molecular response in Brassica juncea.

Cadmium is a hazardous heavy metal; its presence in the agricultural soil constrains the crop productivity and restricts crop plants from reaching their full genetic potential. In the present study, two Brassica juncea cultivars (Pusa Bold and Pusa Jaikisan), were exposed to different concentrations of cadmium (Cd) as cadmium chloride (CdCl2) (50 microM, 100 microM, 150 microM, and 200 microM). The effect of cadmium on seed germination ratio, changes in the root and shoot length, plant dry weight, moisture content, metal tolerance index, antioxidant enzyme activity and lipid peroxidation were studied. The consequence of cadmium stress at the molecular level was studied using a key gene Phytochelatin Synthase (PCS). The results of our study suggested that, exposure of cadmium affected the seed germination, growth rate, biomass content and antioxidant enzyme activities in the root, shoot and leaves of both the cultivars. Transcript expression of PCS was increased with increasing CdCl2 concentration in both the cultivars. Based on the results, it was concluded that, Brassica juncea Cv Pusa Jaikisan is more tolerant to cadmium toxicity than the Pusa Bold. These findings could be used to develop heavy metal stress tolerant plants and more importantly, detoxification of heavy metals in the soil.

Influence of genotypic variations on antioxidant properties in different fractions of tomato.

UNLABELLED: The purpose of this study was to determine the antioxidant potential of phytochemicals present in 15 commercially important tomato genotypes specifically developed for growing in different geographical regions (high altitude and plain). Antioxidant components of tomatoes, namely lycopene, anthocyanin, ascorbic acid, total phenolics, quenching capacity of free radicals, and titratable acidity were analyzed in skin, pulp and seed fractions of the tomato fruits. Results of our study revealed that the antioxidant potency of tomato fruit fractions were in the order of Skin>Pulp>Seeds. Lycopene, anthocyanin content and free radical quenching ability was higher in the high altitude cultivars, whereas total phenolics, ascorbic acid and titratable acidity were seen higher in the plain region cultivars. In general, the outcome of this study showed that, the high altitude cultivars (Sindhu and Shalimar) were superior in antioxidant capacities. In conclusion, with this study it could be established that genetic factors play an important role in determining the antioxidants level and activity of the tomato genotypes and hence it is very important to select the right genotype to get the maximum health benefit. PRACTICAL APPLICATION: Phytochemicals present in the tomatoes are the major determinants of antioxidant potency of the fruits. To study the effect of genotype, it is necessary to grow the cultivars in ideal condition to assess the antioxidants level and activity, to select the right genotype for human consumption that gives better physiological benefit to the consumer.