Metachelins, Mannosylated and N‑Oxidized Coprogen-Type Siderophores from <i>Metarhizium robertsii</i>

Under iron-depleted culture conditions, the entomopathogenic fungus <i>Metarhizium robertsii</i> (Bischoff, Humber, and Rehner) (= <i>M. anisopliae</i>) produces a complex of extracellular siderophores including novel O-glycosylated and N-oxidized coprogen-type compounds as well as the known fungal siderophores <i>N</i>^α-dimethylcoprogen (NADC) and dimerumic acid (DA). Metachelin A (<b>1</b>), the most abundant component in the <i>M. robertsii</i> siderophore mixture, was characterized as a 1094 Da analogue of NADC that is O-glycosylated by β-mannose at both terminal hydroxyl groups and N-oxidized at the dimethylated α-nitrogen. The mixture also contained a 1078 Da analogue, metachelin B (<b>2</b>), which lacks the <i>N</i>-oxide modification. Also characterized were the aglycone of <b>1</b>, i.e., the <i>N</i>-oxide of NADC (<b>3</b>), and the monomannoside of DA (<b>6</b>). <i>N</i>-Oxide and <i>O</i>-glycosyl substituents are unprecedented among microbial siderophores. At high ESIMS source energy and at room temperature in DMSO, <b>1</b> underwent Cope elimination, resulting in loss of the <i>N</i>^α-dimethyl group and dehydration of the α–β bond. High-resolution ESIMS data confirmed that all tri- and dihydroxamate siderophores (<b>1</b>–<b>6</b>) complex with trivalent Fe, Al, and Ga. In a chrome azurol S assay, all of the <i>M. robertsii</i> siderophores showed iron-binding activity roughly equivalent to that of desferrioxamine B

Metacridamides A and B, Macrocycles from Conidia of the Entomopathogenic Fungus <i>Metarhizium acridum</i>

<i>Metarhizium acridum</i>, an entomopathogenic fungus, has been commercialized and used successfully for biocontrol of grasshopper pests in Africa and Australia. Its conidia produce two novel 17-membered macrocycles, metacridamides A (<b>1</b>) and B (<b>2</b>), which consist of a Phe unit condensed with a nonaketide. Planar structures were elucidated by a combination of mass spectrometric and NMR techniques. Following hydrolysis of <b>1</b>, chiral amino acid analysis assigned the l-configuration to the Phe unit. A crystal structure established the absolute configuration of the eight remaining stereogenic centers in <b>1</b>. Metacridamide A (<b>1</b>) showed cytotoxicity to three cancer lines with IC₅₀'s of 6.2, 11.0, and 10.8 μM against Caco-2 (epithelial colorectal adenocarcinoma), MCF-7 (breast cancer), and HepG2/C3A (hepatoma) cell lines, respectively. In addition, metacridamide B (<b>2</b>) had an IC₅₀ of 18.2 μM against HepG2/C3A, although it was inactive at 100 μM against Caco-2 and MCF-7. Neither analogue showed antimicrobial, phytotoxic, or insecticidal activity

Estudi per a la transformació d'un taller de tecnologia en un espai "maker" d'un institut de secundària

Organitzacions de nivell internacional, posen de manifest una educació desfasada, incapaç de donar resposta a les necessitats laborals presents i de futur (World Economic Forum, 2017). El present document planteja el moviment "Maker" com a eina per millorar habilitats, com el pensament crític i creatiu, la resolució de problemes i competències de l'àmbit STEAM i Digital, alineades amb les necessitats laborals. També es recull l'estat de l'art del moviment "Maker" i quines són les bases del moviment i la seva filosofia. S'analitzen els espais "Maker" en entorns escolars, les possibilitats formatives, la planificació per a la implantació i els avantatges i inconvenients. Finalment es plantegen tres activitats didàctiques, una lligada al taller tradicional (construcció amb eines) i les altres dues a espais "Makers" (impressió 3D i talladora làser). Comparar les activitats, permet mostrar com els espais "Maker" tenen una clara tendència a treballar sobre l'àmbit digital i en menor grau també sobre l'àmbit matemàtic i el personal i social

HPLC-MS analysis of cowpea extracts for destruxin (DTX) production.

<p>(A) Analysis of not colonized (free of fungus) plants (negative control); (B) plants endophytically colonized by <i>Metarhizium robertsii</i> ARSEF 2575; and (C) not-colonized plants spiked with DTX standards (positive control). The cowpea seeds, both fungus-inoculated and control (not colonized) were incubated on moist filter paper under optimal light (16L∶8D) and temperature (25°C) conditions for 12 days at which time the germlings had developed roots, stems, cotyledons and two true leaves. DTXs were extracted from entire plants using methanol 100% and SPE-C18 cartridges.</p

Time course of <i>in vitro</i> production of DTXs A, B, and E by <i>Metarhizium anisopliae</i> s.l. ARSEF 759.

<p>Destruxin concentrations in supernatants of submerged liquid cultures were determined by quantitative HPLC-UV analysis of the major components, viz., DTXs A, B and E. Values are expressed in mg DTXs per g dry weight mycelium.</p

Mean mortality (%) ± standard error of <i>Tenebrio molitor</i> larvae 5 days after treatment, and <i>Galleria mellonella</i> 3 days after treatment.

<p>Bioassays were performed 3 times (using two replicates for each isolate) under controlled conditions (27°C), using new batches of larvae and conidia in each bioassay. Controls were treated with Tween 80 (0.01%) solution. Means followed by the same letter in a column do not differ statistically (<i>P</i> ≥ 0.05) (Kruskal-Wallis test followed by Student-Newman-Keuls).</p

Time course of <i>in vitro</i> production of DTXs A, B, and E by <i>Metarhizium robertsii</i> ARSEF 2575.

<p>Destruxin concentrations in supernatant of submerged liquid cultures were determined by quantitative HPLC analysis of the major components, viz., DTXs A, B and E. Values are expressed in mg DTXs per g dry weight mycelium.</p

<i>Metarhizium</i> spp. isolates used in this study, including their hosts and origins (state and country).

<p>* USDA-ARS Collection of Entomopathogenic Fungal Cultures, Ithaca, NY.</p><p>Identifications were provided September 2012 by curator of ARSEF* Richard Humber.</p