Characterization of the superoxide dismutase SOD1 gene of Kluyveromyces marxianus L3 and improved production of SOD activity

Superoxide dismutase (SOD) activity is one major defense line against oxidative stress for all of the aerobic organisms, and industrial production of this enzyme is highly demanded. The Cu/Zn superoxide dismutase gene (KmSOD1) of Kluyveromyces marxianus L3 was cloned and characterized. The deduced KmSod1p protein shares 86% and 71% of identity with Kluyveromyces lactis and Saccharomyces cerevisiae Sod1p, respectively. The characteristic motifs and the amino acid residues involved in coordinating copper and zinc and in enzymatic function were conserved. To the aim of developing a microbial production of Cu/Zn superoxide dismutase, we engineered the K. marxianus L3 strain with the multicopy plasmid YG-KmSOD1 harboring the KmSOD1 gene. The production of KmSOD1p in K. marxianus L3 and K. marxianus L3 (pYG-KmSOD1) in response to different compositions of the culture medium was evaluated. The highest specific activity (472 U(SOD) mg(prot) (-1)) and the highest volumetric yield (8.8 x 10(5) U(SOD) l(-1)) were obtained by the recombinant strain overexpressing KmSOD1 in the presence of Cu(2+) and Zn(2+) supplements to the culture media. The best performing culture conditions were positively applied to a laboratory scale fed-batch process reaching a volumetric yield of 1.4 x 10(6) U(SOD) l(-1)

Emergence of associative learning in a neuromorphic inference network

OBJECTIVE: In the theoretical framework of predictive coding and active inference, the brain can be viewed as instantiating a rich generative model of the world that predicts incoming sensory data while continuously updating its parameters via minimization of prediction errors. While this theory has been successfully applied to cognitive processes - by modelling the activity of functional neural networks at a mesoscopic scale - the validity of the approach when modelling neurons as an ensemble of inferring agents, in a biologically plausible architecture, remained to be explored. APPROACH: We modelled a simplified cerebellar circuit with individual neurons acting as Bayesian agents to simulate the classical delayed eyeblink conditioning protocol. Neurons and synapses adjusted their activity to minimize their prediction error, which was used as the network cost function. This cerebellar network was then implemented in hardware by replicating digital neuronal elements via a low-power microcontroller. MAIN RESULTS: Persistent changes of synaptic strength - that mirrored neurophysiological observations - emerged via local (neurocentric) prediction error minimization, leading to the expression of associative learning. The same paradigm was effectively emulated in low-power hardware showing remarkably efficient performance compared to conventional neuromorphic architectures. SIGNIFICANCE: These findings show that: i) an ensemble of free energy minimizing neurons - organized in a biological plausible architecture - can recapitulate functional self-organization observed in nature, such as associative plasticity, and ii) a neuromorphic network of inference units can learn unsupervised tasks without embedding predefined learning rules in the circuit, thus providing a potential avenue to a novel form of brain-inspired artificial intelligence

The Configuration of the C(5) Carbon Atom in the Germacranic Sesquiterpene Ageratriol

The configuration R for the C(5) atom in ageratriol has already been proposed on the basis of the results of asymmetrical esterification. It is now confirmed by transformation into a meso compound

REGIOSPECIFIC CONVERSION OF ALPHA,BETA-EPOXY ACETATES TO 3-CHLORO-2-HYDROXY ACETATES

3-chloro-2-hydroxy acetates are easily obtained by treating alpha,beta-epoxy acetates with chlorotrimethylsilane-dimethyl sulphoxide in acetonitrile

Ferrocene promoted addition of methyl 2,2-dichloro-carboxylates to 1-alkenes

The Kharasch addition of methyl 2,2-dichlorocarboxylates to 1-alkenes is promoted by ferrocene in DMF at 100 degrees C, affording 1:1 adducts in satisfactory yields

TRIMETHYLCHLOROSILANE-MEDIATED FORMATION OF 2-CHLOROCYCLOHEXYL SULPHIDES BY SULPHOXIDES

The title 2-chlorocyclohexyl sulfides, e.g. I (R = Me, Et, Me2CH, Bu) were prepd. by treating cyclohexene with the corresponding alkyl sulfoxides RSOR in the presence of Me3SiCl. Unsym. sulfoxides, e.g. EtSOBu gave a mixt. of products I (R = Et, Bu). Tetramethylene sulfoxide (II) gave aldehyde I (R = CH2CH2CH2CHO) as the major product. A mechanism is presented in which 2 mol. of sulfoxide form an intermediates S-alkoxysulfonium salt

Attempted Nucleophilic Attack of Cyanide Ion on alfa-beta-unsaturated p-Tosylhydrazones.

The reactivity of alfa-beta-unsaturated p-Tosylhydrazones toward ion cyanide as nucleophile. In a aqueous-dichloromethane two-phases reaction, using benzyltriethyammonium chloride as a phase-transfer catalyst, we obtained hydrocyanation of tosylhydrazones of cycloexanone and other unconjugated substrates, while the C=N of conjugated one, resists nucleophilic attack of cyanide ion

A Route to 3,4-Polymethylenepyrazoles via Olefinic Toluene-p-sulphonylhydrazones

Tosylhydrazones of cycloalkenyl carbonyl compounds were subjected to base-catalysed decomposition (K2CO3-MeOH) in aim to obtain 3,4-polymethylenepyrazoles. The cycloaddition occours in high yelds and solvolysis competes with cycloaddition only with cyclopentenyl derivative

CARBONYL REGENERATION FROM OXIMES AND SEMICARBAZONES BY TRIMETHYLCHLOROSILANE-DIMETHYLSULFOXIDE

Treatment of oximes and semicarbazones of saturated and (alpha,beta-unsaturated ketones and aldehydes with trimethylchlorosilane-dimethyl sulphoxide in dry acetonitrile affords the corresponding carbonyl compounds in excellent yields under mild conditions