Sclerotium rolfsii lectin induces opposite effects on normal PBMCs and leukemic Molt-4 cells by recognising TF antigen and its variants as receptors

Glycoconjugate Journal - Sclerotium rolfsii lectin (SRL) exerts apoptotic effect against various cancer cells and an antitumor activity on mice with colon and breast cancer xenografts. The current...     

Application of optical imaging and spectroscopy to radiation biology

Optical imaging and spectroscopy is a diverse field that has been of critical importance in a wide range of areas in radiation research. It is capable of spanning a wide range of spatial and temporal scales, and has the sensitivity and specificity needed for molecular and functional imaging. This review will describe the basic principles of optical imaging and spectroscopy, highlighting a few relevant applications to radiation research.     

Biochemical characterization of a chloroplast localized fatty acid reductase from Arabidopsis thaliana

Primary long-chain fatty alcohols are present in a variety of phyla. In eukaryotes, the production of fatty alcohols is catalyzed by fatty acyl-CoA reductase (FAR) enzymes that convert fatty acyl-CoAs or acyl-ACPs into fatty alcohols. Here, we report on the biochemical properties of a purified plant FAR, Arabidopsis FAR6 (AtFAR6). In vitro assays show that the enzyme preferentially uses 16 carbon acyl-chains as substrates and produces predominantly fatty alcohols. Free fatty acids and fatty aldehyde intermediates can be released from the enzyme, in particular with suboptimal chain lengths and concentrations of the substrates. Both acyl-CoA and acyl-ACP could serve as substrates. Transient expression experiments in Nicotiana tabacum showed that AtFAR6 is a chloroplast localized FAR. In addition, expression of full length AtFAR6 in Nicotiana benthamiana leaves resulted in the production of C16:0-alcohol within this organelle. Finally, a GUS reporter gene fusion with the AtFAR6 promoter showed that the AtFAR6 gene is expressed in various tissues of the plant with a distinct pattern compared to that of other Arabidopsis FARs, suggesting specialized functions in planta.     

Purification and characterization of a wound-induced ω-hydroxyfatty acid:NADP oxidoreductase from potato tuber disks (Solanum tuberosum L.)

ω-Hydroxyfatty acid dehydrogenase (ω-hydroxyfatty acid:NADP oxidoreductase) catalyzes the reaction ω-hydroxyfatty acid + NADP ? ω-oxofatty acid + NADPH +H⁺. In wound-healing potato tuber disks, the ω-oxofatty acid generated by this enzyme is further oxidized to the corresponding dicarboxylic acid by a separate enzyme, ω-oxofatty acid dehydrogenase. ω-Hydroxy acid dehydrogenase, but not ω-oxo acid dehydrogenase, was found to be induced by wounding potato tubers. ω-Hydroxy acid dehydrogenase has been purified 600-fold to near homogeneity from wound-healing potato tuber disks by a combination of gel filtration, anion-exchange, and hydroxylapatite chromatography followed by NADP-Sepharose affinity chromatography, in about 1% yield. The molecular weight and Stokes radius of this enzyme as determined by gel exclusion chromatography are 60,000 and 31 Å, respectively. Sodium dodecyl sulfate-gel electrophoresis gave a molecular weight of 31,000, indicating that the deydrogenase is a dimer with subunits of similar molecular weight. The pH optima for the reaction in the forward and reverse directions are 9.5 and 8.5, respectively, and V in the forward and reverse directions are 140 and 3200 nmol/min/mg, respectively. Apparent K_m values for NADP, 16-hydroxyhexadecanoic acid, NADPH, and 16-oxohexadecanoic acid are 100, 20, 5, and 7 μm respectively. The equilibrium constant of the reaction at pH 9.5 and 30 °C is 1.4 × 10^?9m. The enzyme preparation did not show any stereospecificity for hydride transfer from NADPH to 16-oxohexadecanoic acid.     

Rapid Determination of Oxygen Saturation and Vascularity for Cancer Detection

A rapid heuristic ratiometric analysis for estimating tissue hemoglobin concentration and oxygen saturation from measured tissue diffuse reflectance spectra is presented. The analysis was validated in tissue-mimicking phantoms and applied to clinical measurements in head and neck, cervical and breast tissues. The analysis works in two steps. First, a linear equation that translates the ratio of the diffuse reflectance at 584 nm and 545 nm to estimate the tissue hemoglobin concentration using a Monte Carlo-based lookup table was developed. This equation is independent of tissue scattering and oxygen saturation. Second, the oxygen saturation was estimated using non-linear logistic equations that translate the ratio of the diffuse reflectance spectra at 539 nm to 545 nm into the tissue oxygen saturation. Correlations coefficients of 0.89 (0.86), 0.77 (0.71) and 0.69 (0.43) were obtained for the tissue hemoglobin concentration (oxygen saturation) values extracted using the full spectral Monte Carlo and the ratiometric analysis, for clinical measurements in head and neck, breast and cervical tissues, respectively. The ratiometric analysis was more than 4000 times faster than the inverse Monte Carlo analysis for estimating tissue hemoglobin concentration and oxygen saturation in simulated phantom experiments. In addition, the discriminatory power of the two analyses was similar. These results show the potential of such empirical tools to rapidly estimate tissue hemoglobin in real-time spectral imaging applications.     

Thrombin-like serine protease,antiquorin from Euphorbia antiquorum latex induces platelet aggregation via PAR1-Akt/p38 signaling axis

Plant latex proteases (PLPs) are pharmacologically essential and are integral components of traditional medicine in the management of bleeding wounds. PLPs are known to promote blood coagulation and stop bleeding by interfering at various stages of hemostasis. There are a handful of scientific reports on thrombin-like enzymes characterized from plant latices. However, the role of plant latex thrombin-like enzymes in platelet aggregation is not well known. In the present study, we attempted to purify and characterize thrombin-like protease responsible for platelet aggregation. Among tested plant latices, Euphorbia genus latex protease fractions (LPFs) induced platelet aggregation. In Euphorbia genus, E. antiquorum LPF (EaLPF) strongly induced platelet aggregation and attenuated bleeding in mice. The purified thrombin-like serine protease, antiquorin (Aqn) is a glycoprotein with platelet aggregating activities that interfere in intrinsic and common pathways of blood coagulation cascade and alleviates bleeding and enhanced excision wound healing in mice. In continuation, the pharmacological inhibitor of PAR1 inhibited Aqn-induced phosphorylation of cPLA₂, Akt, and P38 in human platelets. Moreover, Aqn-induced platelet aggregation was inhibited by pharmacological inhibitors of PAR1, PI3K, and P38. These data indicate that PAR1-Akt/P38 signaling pathways are involved in Aqn-induced platelet aggregation. The findings of the present study may open up a new avenue for exploiting Aqn in the treatment of bleeding wounds.     

Acyl-lipid thioesterase1–4 from Arabidopsis thaliana form a novel family of fatty acyl–acyl carrier protein thioesterases with divergent expression patterns and substrate specificities

Hydrolysis of fatty acyl thioester bonds by thioesterases to produce free fatty acids is important for dictating the diversity of lipid metabolites produced in plants. We have characterized a four-member family of fatty acyl thioesterases from Arabidopsis thaliana, which we have called acyl-lipid thioesterase1 (ALT1), ALT2, ALT3, and ALT4. The ALTs belong to the Hotdog fold superfamily of thioesterases. ALT-like genes are present in diverse plant taxa, including dicots, monocots, lycophytes, and microalgae. The four Arabidopsis ALT genes were found to have distinct gene expression profiles with respect to each other. ALT1 was expressed specifically in stem epidermal cells and flower petals. ALT2 was expressed specifically in root endodermal and peridermal cells as well as in stem lateral organ boundary cells. ALT3 was ubiquitously expressed in aerial and root tissues and at much higher levels than the other ALTs. ALT4 expression was restricted to anthers. All four proteins were localized in plastids via an N-terminal targeting sequence of about 48 amino acids. When expressed in Escherichia coli, the ALT proteins used endogenous fatty acyl–acyl carrier protein substrates to generate fatty acids that varied in chain length (C6–C18), degree of saturation (saturated and monounsaturated), and oxidation state (fully reduced and β-ketofatty acids). Despite their high amino acid sequence identities, each enzyme produced a different profile of lipids in E. coli. The biological roles of these proteins are unknown, but they potentially generate volatile lipid metabolites that have previously not been reported in Arabidopsis.