172 research outputs found

    Disruption of VGLUT1 in cholinergic medial habenula projections increases nicotine self-administration

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    Cholinergic projections from the medial habenula (MHb) to the interpeduncular nucleus (IPN) have been studied for their complex contributions to nicotine addiction and have been implicated in nicotine reinforcement, aversion, and withdrawal. While it has been established that MHb cholinergic projections co-release glutamate, no direct evidence has demonstrated a role for this glutamate projection in nicotine consumption. In the present study, a novel floxed Slc17a7 (VGLUT1) mouse was generated and used to create conditional knockout (cKO) mice that lack VGLUT1 in MHb cholinergic neurons. Loss of Slc17a7 expression in ventral MHb cholinergic neurons was validated using fluorescent in situ hybridization, and immunohistochemistry was used to demonstrate a corresponding reduction of VGLUT1 protein in cholinergic terminals in the IPN. We also used optogenetics-assisted electrophysiology to evoke excitatory post-synaptic currents in IPN and observed a reduction of glutamatergic currents in the cKO, supporting the functional disruption of VGLUT1 in MHb to IPN synapses. cKO mice exhibited no gross phenotypic abnormalities and displayed normal thigmotaxis and locomotor behavior in the open-field assay. When trained to lever press for food, there was no difference between control and cKO. However, when tested in a nicotine self-administration procedure we found that the loss of VGLUT1-mediated glutamate co-release led to increased responding for nicotine. These findings indicate that glutamate co-release from ventral MHb cholinergic neurons opposes nicotine self-administration, and provide additional support for targeting this synapse to develop potential treatments for nicotine addiction

    Carboxylation of phenols and asymmetric nucleophile addition across C=C bond

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    The regioselective carboxylation of electron-rich (hetero)aromatics employing decarboxylases in the redox-neutral (reverse) carboxylation reaction using bicarbonate or CO2(g) is currently exploited for the biocatalytic synthesis of carboxylic acids.1 Three enzyme classes exert complementary regioselectivities through diverse mechanisms: (i) Whereas the o-carboxylation of phenols (an equivalent to the Kolbe-Schmitt reaction) is mediated by Zn2+-dependent o-benzoic acid (de)carboxylases,2 (ii) the -carboxylation of hydroxystyrenes is catalysed by phenolic/ferulic acid (de)carboxylases acting via a pair of Tyr-Arg residues.3 (iii) Surpringly, these enzymes also exhibit a catalytic promiscuity for the nucleophile addition of H2O,4 NH2-OMe, cyanide and n-Pr-SH across the vinyl C=C bond via a quinone-methide intermediate, which yields the corresponding (S)-configurated adducts in up to 91% e.e.5 (iv) In search of ATP-independent regio-complementary p-benzoic acid (de)carboxylases, we discovered that 3,4-dihydroxybenzoic acid decarboxylase from Enterobacter cloacae6 (DHBDC_Ec) surprisingly depends on prenylated FMN7 as cofactor. In an attempt to propose a mechanism for the carboxylation of catechol by DHBDC_Ec, QM calculations revealed that the transient formation of a 1,3-dipolar cycloaddition product (as suggested for the decarboxylation of cinnamic acid with ferulic acid decarboxylase from S. cerevisiae8) was highly disfavored (\u3e30 kcal/M). As an alternative, we propose a mono-covalent nucleophile adduct involving a prFMN iminium electrophile (~14 kcal/M). Please click Additional Files below to see the full abstract

    Narrow genetic base in forest restoration with holm oak (Quercus ilex L.) in Sicily

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    In order to empirically assess the effect of actual seed sampling strategy on genetic diversity of holm oak (Quercus ilex) forestations in Sicily, we have analysed the genetic composition of two seedling lots (nursery stock and plantation) and their known natural seed origin stand by means of six nuclear microsatellite loci. Significant reduction in genetic diversity and significant difference in genetic composition of the seedling lots compared to the seed origin stand were detected. The female and the total effective number of parents were quantified by means of maternity assignment of seedlings and temporal changes in allele frequencies. Extremely low effective maternity numbers were estimated (Nfe \approx 2-4) and estimates accounting for both seed and pollen donors gave also low values (Ne \approx 35-50). These values can be explained by an inappropriate forestry seed harvest strategy limited to a small number of spatially close trees

    Safety of vitamin D2 mushroom powder as a novel food pursuant to Regulation (EU) 2015/2283

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    Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on vitamin D2 mushroom powder as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is an ingredient produced from Agaricus bisporus mushrooms that have been exposed to ultraviolet (UV) light to induce the conversion of provitamin D2 (ergosterol) to vitamin D2 (ergocalciferol). The NF contains concentrations of vitamin D provided by vitamin D2 in the ranges of 1,000\u20131,300 \u3bcg/g. The information provided on the manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF in a variety of foods and beverages, including food for special medical purposes and food supplements. The target population is the general population except for food supplements, for which the target population is individuals above seven months of age. The Panel concludes that the NF, used as an ingredient, is safe for the general population at the proposed condition of use in foods and beverages and that the NF used as a food supplement, is safe for individuals above 1 year. The Panel, however, notes that the UL for infants aged 0\u20136 months may be exceeded in high consumers of infant formula (IF) and/or follow-on formula (FoF) that may also be high consumers of foods fortified with the NF and for infants aged 7\u201312 months consuming a daily vitamin D oral supplementation of 10 \u3bcg. However, the Panel considers this scenario unlikely as complementary feeding in high consumers of IF and/or FoF may be limited. Furthermore, the combined consumption of vitamin D via fortified foods and supplements does not specifically concern this NF application. The Panel concludes that the NF is safe under the proposed conditions of use for the proposed target populations

    Safety of astaxanthin for its use as a novel food in food supplements

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    Following a request from the European Commission, the Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the safety of astaxanthin when used as a novel food in food supplements at maximum levels of 8 mg/day, taking into account the overall cumulative intake of astaxanthin from all food sources. In 2014, the NDA Panel assessed the safety of the novel astaxanthin-rich ingredient derived from microalgae Haematococcus pluvialis in the context of an application submitted under Regulation (EC) No 258/1997. In that opinion, the NDA Panel considered that the acceptable daily intake (ADI) for astaxanthin was 0.034 mg/kg body weight (bw) set by the EFSA FEEDAP Panel in 2014. In 2019, the FEEDAP Panel adopted an opinion which concerned the renewal of the authorisation of dimethyldisuccinate-astaxanthin and a new use of the additive for crustaceans and other fish than salmonids. In that assessment, the FEEDAP Panel derived a new ADI of 0.2 mg astaxanthin/kg bw which replaced the ADI of 0.034 mg/kg bw established in 2014. By taking into account an updated exposure assessment for astaxanthin from the background diet (fish and crustaceans) in combination with 8 mg from food supplements, the NDA Panel concludes that (i) such combined exposure to astaxanthin is safe for adults, (ii) 14 to < 18 years old adolescents reach the ADI, and (iii) the ADI is exceeded by 28% in children aged 10 to < 14 years and up to 524% in infants aged 4–6 months

    A Combined Nucleic Acid and Protein Analysis in Friedreich Ataxia: Implications for Diagnosis, Pathogenesis and Clinical Trial Design

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    BACKGROUND: Friedreich's ataxia (FRDA) is the most common hereditary ataxia among caucasians. The molecular defect in FRDA is the trinucleotide GAA expansion in the first intron of the FXN gene, which encodes frataxin. No studies have yet reported frataxin protein and mRNA levels in a large cohort of FRDA patients, carriers and controls. METHODOLOGY/PRINCIPAL FINDINGS: We enrolled 24 patients with classic FRDA phenotype (cFA), 6 late onset FRDA (LOFA), all homozygous for GAA expansion, 5 pFA cases who harbored the GAA expansion in compound heterozygosis with FXN point mutations (namely, p.I154F, c.482+3delA, p.R165P), 33 healthy expansion carriers, and 29 healthy controls. DNA was genotyped for GAA expansion, mRNA/FXN was quantified in real-time, and frataxin protein was measured using lateral-flow immunoassay in peripheral blood mononuclear cells (PBMCs). Mean residual levels of frataxin, compared to controls, were 35.8%, 65.6%, 33%, and 68.7% in cFA, LOFA, pFA and healthy carriers, respectively. Comparison of both cFA and pFA with controls resulted in 100% sensitivity and specificity, but there was overlap between LOFA, carriers and controls. Frataxin levels correlated inversely with GAA1 and GAA2 expansions, and directly with age at onset. Messenger RNA expression was reduced to 19.4% in cFA, 50.4% in LOFA, 52.7% in pFA, 53.0% in carriers, as compared to controls (p<0.0001). mRNA levels proved to be diagnostic when comparing cFA with controls resulting in 100% sensitivity and specificity. In cFA and LOFA patients mRNA levels correlated directly with protein levels and age at onset, and inversely with GAA1 and GAA2. CONCLUSION/SIGNIFICANCE: We report the first explorative study on combined frataxin and mRNA levels in PBMCs from a cohort of FRDA patients, carriers and healthy individuals. Lateral-flow immunoassay differentiated cFA and pFA patients from controls, whereas determination of mRNA in q-PCR was sensitive and specific only in cFA
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