The parasporal crystals of Bacillus pumilus strain 15.1: a potential virulence factor?

Bacillus pumilus strain 15.1 was previously found to cause larval mortality in the Med-fly 27 Ceratitis capitata and was shown to produce crystals in association with the spore. As 28 parasporal crystals are well-known as invertebrate-active toxins in entomopathogenic 29 bacteria such as Bacillus thuringiensis (Cry and Cyt toxins) and Lysinibacillus sphaericus (Bin 30 and Cry toxins), the B. pumilus crystals were characterised. The crystals were composed of a 31 45 kDa protein that was identified as an oxalate decarboxylase by peptide mass 32 fingerprinting, N-terminal sequencing and by comparison with the genome sequence of strain 33 15.1. Synthesis of crystals by a plasmid-cured derivative of strain 15.1 (produced using a 34 novel curing strategy), demonstrated that the oxalate decarboxylase was encoded 35 chromosomally. Crystals spontaneously solubilized when kept at low temperatures and the 36 protein produced was resistant to trypsin treatment. The insoluble crystals produced by 37 B. pumilus 15.1 did not show significant toxicity when bioassayed against C. capitata larvae, 38 but once the OxdD protein was solubilized, an increase of toxicity was observed. We also 39 demonstrate that the OxdD present in the crystals has oxalate decarboxylate activity as the 40 formation of formate was detected, which suggests a possible mechanism for B. pumilus 15.1 41 activity. To our knowledge, the characterization of the B. pumilus crystals as oxalate 42 decarboxylase is the first report of the natural production of parasporal inclusions of an 43 enzyme

Hypoxia signaling and cholesterol/steroidogenic acute regulatory protein 1 axis: interplay and role in alcohol and non-alcohol-related liver diseases

Metabolic zonation in the liver carries out the maintenance of organ and body homeostasis. Hypoxia is an inherent physiological feature of the liver and contributes to the zonal properties of the hepatic parenchyma. As a master regulator of hypoxia, the transcription factor hypoxia-inducing factor (HIF) is stabilized primarily by oxygen availability, and it is thought to contribute to steatohepatitis due to alcohol-related (ASH) and non-alcohol-related liver disease (NASH). Cholesterol has emerged as an important player in both diseases, and hypoxia increases hepatic cholesterol levels. Steroidogenic acute regulatory protein 1 (STARD1) is a mitochondrial outer membrane protein that transfers cholesterol to mitochondrial inner membrane for metabolic processing and acts as the rate-limiting step in the alternative pathway of bile acid synthesis in hepatocytes. STARD1 expression increases in ASH and NASH and determines the accumulation of cholesterol in mitochondria, which impacts the physico-chemical mitochondrial membranes properties and as a consequence impairs the activity of specific mitochondrial solute carriers, such as the 2-oxoglutarate carrier (2-OGC), limiting the exchange between cytosolic glutathione and mitochondrial 2-oxoglutarate (2-OG). Although HIF-1 is stabilized in hypoxia largely due to the requirement of prolylhydroxylases (PHDs) for oxygen to signal HIF degradation, PHDs are also dependent on 2-OG, and therefore it is conceivable that impairment of 2-OGC by STARD1-mediated cholesterol accumulation may contribute to HIF-1 stabilization due in part to decreased availability of cytosolic 2-OG. In this perspective, this review explores the interplay between HIF-1 stabilization and STARD1 induction and the potential contribution of this functional relationship to ASH and NASH

Novel incorporation of red-stage haematococcus pluvialis wet paste as a colourant and enhancer of the organoleptic and functional properties of filloas †

Haematococcus pluvialis Flotow is a microalga used as a nutraceutical, due to its high content in bioactive compounds, mainly carotenoids, in which astaxanthin stands out [1]. Furthermore, H. plu- vialis has shown a high antioxidant potential, and combined with its intense red colour, this microalga could have dual functionality: as a colourant and a bioactive ingredient [ 2]. The process to obtain this ingredient involves several transformation steps—namely, lyophilisation and saponification—raising the costs to develop and obtain free astaxanthin, which paradoxically presents greater instability and solubility than its esterified counterpart [ 3]. Thus, this study provides an alternative approach for the application of red, astaxanthin-rich, H. pluvialis wet paste as a partial substitute for wheat flour (7% and 13% w/w) in the preparation of filloas (Galician pancakes), a typical dessert from the northwestern region of the Iberian Peninsula. To evaluate its power as a natural pigment, the stability of colour over time (3, 6, and 9 days) was measured, and the results were compared with those of a commercial colourant. At the same time, its physicochemical properties such as the microbiological profile were measured to determine its functionality as a food preservative. As a result, redness stability (a*) of 8% higher than that of the commercial colourant was obtained for the maximum concentration of H. pluvialis analysed. The texture showed a significant response (p < 0.02), improving its properties as the concentration of the microalga increased, which showed a tenacity of 3.23 N and extensibility of 15.10 mm during the first 6 days, i.e., a 52% and 19% improvement, respectively, in relation to the control group. In turn, an enrichment of carotenoids, fatty acids, and phenolic com- pounds, in combination with a potential moderator of microbiological degradation by this unicellular organism, gives added value to this food matrix.This research was funded by project ED431 2020/06 (Galician Competitive Research Groups Xunta de Galicia). This study was supported by project EQC2018-005011-P (Ministry of Science, Innovation and Universities, Spain). All these programmes are co-funded by FEDER (EU). The authors are also grateful to Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/2020); to FCT for S. Heleno (CEECIND/03040/2017) and L. Barros contracts through the individual and institutional scientific employment programme contract, respectively. This article is based upon work from the Sample Preparation Study Group and Network, supported by the Division of Analytical Chemistry of the European Chemical Societyinfo:eu-repo/semantics/publishedVersio

Detection of anti-hepatitis C virus antibodies by ELISA using synthetic peptides

A novel ELISA assay for the detection of anti-hepatitis C virus antibodies in the sera of infected individuals is described. This assay is based on a mixture of three 15-amino acid synthetic peptides encompassing regions of core and NS4 proteins of hepatitis C virus. Comparison with other available ELISA assays based on recombinant polypeptides shows that, short synthetic peptides have the advantage over some larger recombinant peptides by giving higher specificity without loss of sensitivity

The generally recognized as safe (GRAS) microalgae Haematococcus pluvialis (wet) as a multifunctional additive for coloring and improving the organoleptic and functional properties of foods

This work proposes the application of astaxanthin-rich H. pluvialis wet paste (HPW) as a partial substitute for wheat flour in the preparation of filloas, a dish that combines the basic ingredients of industrial bakery. The nutritional and color profile of HPW-enriched samples was evaluated by comparative analysis with a mixture of synthetic food dyes. The highest content of carotenoids (798 ± 12 µg g−1) and fatty acids (76 ± 2mgg−1) was obtained for a filloa fortified with H. pluvialis in contrast to a non-significant dye response. Subsequently, the color stability of the fortified filloa was evaluated over time (3, 6 and 9 days), as well as its physicochemical properties and microbiological profile. As a result, HPW provided filloas with a longer shelf life, brightness (*L), and texture, in comparison with a mixture of synthetic dyes. In addition, an inhibitory effect of HPW towards mesophilic aerobic microorganisms in the food was obtained.This research was funded by project ED431 2020/06 (Galician Competitive Research Groups Xunta de Galicia). All these pro- grammes are co-funded by FEDER (EU). The authors are also grateful to the Foundation for Science and Technology (FCT; Portugal) for financial support through national funds FCT/ MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/ 00690/2020) and SusTEC (LA/P/0007/2021). Castillo A. acknowl- edges the support of the European Grouping of Territorial Cooperation Galicia-Norte Portugal (GNP, EGTC) under the IACOBUS Program and the MCI of Spain for his contract part of the grant DIN2021-011976 funded by the MCIN/AEI/ 10.13039/501100011033. L. Barros and S. Heleno acknowledge the national funding by FCT, P. I., through the institutional scientific employment program-contract for their contracts, and Filipa A. Fernandes for the PhD grant (SFRH/BD/145467/ 2019).info:eu-repo/semantics/publishedVersio

Spin diffusion versus proximity effect at ferromagnet/superconductor La_(0.7)Ca_(0.3)MnO_(3)/YBa_(2)Cu_(3)O_(7-δ) interfaces

We report on the interplay between magnetism and superconductivity in La_(0.7)Ca_(0.3)MnO_(3)/YBa_(2)Cu_(3)O_(7) structures. We have grown heterostructures (bilayers and trilayers) with a constant thickness of the ferromagnetic layer of 40 unit cells (15 nm) and changing the thickness of the superconductor between 1 (1.2 nm) and 40 unit cells (48 nm). The critical temperature of the bilayers decreases when the thickness of the superconductor is reduced below 10 unit cells, thus providing an estimate of the length scale of superconductivity suppression by spin-polarized quasiparticles in YBa_(2)Cu_(3)O_(7-δ) (YBCO) of 10 nm, much larger than the coherence length. For thickness of the YBCO layer smaller than 4 unit cells; a second mechanism of superconductivity depression comes into play, probably related to the ferromagnetic/superconducting proximity effect. The relative importance in depressing the critical temperature of intrinsic mechanisms (quasiparticle diffusion and proximity effect) and extrinsic ones (intralayer disorder, interface roughness, or reduced dimensionality of ultrathin layers) is discussed

Novel role for amphiregulin in protection from liver injury

Clinically, the Fas and Fas ligand system plays a central role in the development of hepatocyte apoptosis, a process contributing to a broad spectrum of liver diseases. Therefore, the development of therapies aimed at the inhibition of hepatocyte apoptosis is a major issue. Activation of the epidermal growth factor receptor has been shown to convey survival signals to the hepatocyte. To learn about the endogenous response of epidermal growth factor receptor ligands during Fas-mediated liver injury we investigated the expression of epidermal growth factor, transforming growth factor alpha, heparin-binding epidermal growth factor-like growth factor, betacellulin, epiregulin, and amphiregulin in the liver of mice challenged with Fas-agonist antibody. Amphiregulin expression, barely detectable in healthy liver, was significantly up-regulated. Amphiregulin administration abrogated Fas-mediated liver injury in mice and showed direct anti-apoptotic effects in primary hepatocytes. Amphiregulin activated the Akt and signal transducer and activator of transcription-3 survival pathways, and up-regulated Bcl-xL expression. Amphiregulin knock-out mice showed signs of chronic liver damage in the absence of any noxious treatment, and died faster than wild type mice in response to lethal doses of Fas-agonist antibody. In contrast, these mice were more resistant against sublethal liver damage, supporting the hypothesis that chronic liver injury can precondition hepatocytes inducing resistance to subsequent cell death. These results show that amphiregulin is a protective factor induced in response to liver damage and that it may be therapeutic in liver diseases

S-adenosylmethionine regulates MAT1A and MAT2A gene expression in cultured rat hepatocytes: a new role for S-adenosylmethionine in the maintenance of the differentiated status of the liver

Methionine metabolism starts with the formation of S-adenosylmethionine (AdoMet), the most important biological methyl donor. This reaction is catalyzed by methionine adenosyltransferase (MAT). MAT is the product of two different genes: MAT1A, which is expressed only in the adult liver, and MAT2A, which is widely distributed, expressed in the fetal liver, and replaces MAT1A in hepatocarcinoma. In the liver, preservation of high expression of MAT1A and low expression of MAT2A is critical for the maintenance of a functional and differentiated organ. Here we describe that in cultured rat hepatocytes MAT1A expression progressively decreased, as described for other liver-specific genes, and MAT2A expression was induced. We find that this switch in gene expression was prevented by adding AdoMet to the culture medium. We also show that in cultured hepatocytes with decreased MAT1A expression AdoMet addition markedly increased MAT1A transcription in a dose-dependent fashion. This effect of AdoMet was mimicked by methionine, and blocked by 3-deazaadenosine and L-ethionine, but not D-ethionine, indicating that the effect was specific and mediated probably by a methylation reaction. These findings identify AdoMet as a key molecule that differentially regulates MAT1A and MAT2A expression and helps to maintain the differentiated status of the hepatocyte