8 research outputs found
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><sup>α</sup>-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><sup>α</sup>-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
IC<sub>50</sub>'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 IC<sub>50</sub> 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 secundà ria
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 crÃtic i creatiu, la resolució de problemes i competències de l'à mbit 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 didà ctiques, una lligada al taller tradicional (construcció amb eines) i les altres dues a espais "Makers" (impressió 3D i talladora là ser). Comparar les activitats, permet mostrar com els espais "Maker" tenen una clara tendència a treballar sobre l'à mbit digital i en menor grau també sobre l'à mbit matemà tic 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