Context-dependent dual role of SKI8 homologs in mRNA synthesis and turnover.

Eukaryotic mRNA transcription and turnover is controlled by an enzymatic machinery that includes RNA polymerase II and the 3' to 5' exosome. The activity of these protein complexes is modulated by additional factors, such as the nuclear RNA polymerase II-associated factor 1 (Paf1c) and the cytoplasmic Superkiller (SKI) complex, respectively. Their components are conserved across uni- as well as multi-cellular organisms, including yeast, Arabidopsis, and humans. Among them, SKI8 displays multiple facets on top of its cytoplasmic role in the SKI complex. For instance, nuclear yeast ScSKI8 has an additional function in meiotic recombination, whereas nuclear human hSKI8 (unlike ScSKI8) associates with Paf1c. The Arabidopsis SKI8 homolog VERNALIZATION INDEPENDENT 3 (VIP3) has been found in Paf1c as well; however, whether it also has a role in the SKI complex remains obscure so far. We found that transgenic VIP3-GFP, which complements a novel vip3 mutant allele, localizes to both nucleus and cytoplasm. Consistently, biochemical analyses suggest that VIP3-GFP associates with the SKI complex. A role of VIP3 in the turnover of nuclear encoded mRNAs is supported by random-primed RNA sequencing of wild-type and vip3 seedlings, which indicates mRNA stabilization in vip3. Another SKI subunit homolog mutant, ski2, displays a dwarf phenotype similar to vip3. However, unlike vip3, it displays neither early flowering nor flower development phenotypes, suggesting that the latter reflect VIP3's role in Paf1c. Surprisingly then, transgenic ScSKI8 rescued all aspects of the vip3 phenotype, suggesting that the dual role of SKI8 depends on species-specific cellular context.

Whole body protein synthesis and energy expenditure in very low birth weight infants.

The aim of the present work was to study whole body protein synthesis and breakdown, as well as energy metabolism, in very low birth weight premature infants (less than 1500 g) during their rapid growth phase. Ten very low birth weight infants were studied during their first and second months of life. They received a mean energy intake of 114 kcal/kg X day and 3 g protein/kg X day as breast milk or milk formula. The average weight gain was 15 g/kg X day. The apparent energy digestibility was 88%, i.e. 99 kcal/kg X day. Their resting postprandial energy expenditure was 58 kcal/kg X day, indicating that 41 kcal/kg X day was retained. The apparent protein digestibility was 89%, i.e. 2.65 g/kg X day. Their rate of protein oxidation was 0.88 g/kg X day so that protein retention was 1.76 g/kg X day. There was a linear relationship between N retention and N intake (r = 0.78, p less than 0.001). The slope of the regression line indicates a net efficiency of N utilization of 67%. Estimates of body composition from the energy balance, coupled with N balance method, showed that 25% of the gain was fat and 75% was lean tissue. Whole body protein synthesis and breakdown were determined using repeated oral administration of 15N glycine for 60-72 h, and 15N enrichment in urinary urea was measured. Protein synthesis averaged 11.2 g/kg X day and protein breakdown 9.4 g/kg X day. Muscular protein breakdown, as estimated by 3-methylhistidine excretion, contributed to 12% of the total protein breakdown.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrochemical synthesis of mesoporous CoPt nanowires for methanol oxidation

A new electrochemical method to synthesize mesoporous nanowires of alloys has been developed. Electrochemical deposition in ionic liquid-in-water (IL/W) microemulsion has been successful to grow mesoporous CoPt nanowires in the interior of polycarbonate membranes. The viscosity of the medium was high, but it did not avoid the entrance of the microemulsion in the interior of the membrane"s channels. The structure of the IL/W microemulsions, with droplets of ionic liquid (4 nm average diameter) dispersed in CoPt aqueous solution, defined the structure of the nanowires, with pores of a few nanometers, because CoPt alloy deposited only from the aqueous component of the microemulsion. The electrodeposition in IL/W microemulsion allows obtaining mesoporous structures in which the small pores must correspond to the size of the droplets of the electrolytic aqueous component of the microemulsion. The IL main phase is like a template for the confined electrodeposition. The comparison of the electrocatalytic behaviours towards methanol oxidation of mesoporous and compact CoPt nanowires of the same composition, demonstrated the porosity of the material. For the same material mass, the CoPt mesoporous nanowires present a surface area 16 times greater than compact ones, and comparable to that observed for commercial carbon-supported platinum nanoparticles.

Total synthesis of aeruginazole A

The first total synthesis of Aeruginazole A, prepared via a convergent strategy that involved both solid-phase peptide synthesis and solution phase chemistry and that enabled conservation of the stereochemistry of the intermediates, is reported.

Orthogonal protecting groups in the synthesis of tryptophanyl-hexahydropyrroloindoles

The synthesis of various polycyclic systems containing a C3aNi bond between a hexahydropyrrolo[2,3-b]indole and an indole tryptophan is described here. A series of experiments were performed to determine the best combination of five orthogonal protecting groups and the best reaction conditions for formation of said bond, which is a common feature among many recently discovered marine natural products.

Modeling and Synthesis of Tracking Control for the Belt Drive System

Usingof belt for high precision applications has become appropriate because of the rapid development in motor and drive technology as well as the implementation of timing belts in servo systems. Belt drive systems provide highspeed and acceleration, accurate and repeatable motion with high efficiency, long stroke lengths and low cost. Modeling of a linear belt-drive system and designing its position control are examined in this work. Friction phenomena and position dependent elasticity of the belt are analyzed. Computer simulated results show that the developed model is adequate. The PID control for accurate tracking control and accurate position control is designed and applied to the real test setup. Both the simulation and the experimental results demonstrate that the designed controller meets the specified performance specifications.

The Protein quality control system manages plant defence compound synthesis

Jasmonates are ubiquitous oxylipin-derived phytohormones that are essential in the regulation of many development, growth and defence processes. Across the plant kingdom, jasmonates act as elicitors of the production of bioactive secondarymetabolites that serve in defence against attackers. Knowledge of the conserved jasmonate perception and early signalling machineries is increasing, but the downstream mechanisms that regulate defence metabolism remain largely unknown. Herewe showthat, in the legumeMedicago truncatula, jasmonate recruits the endoplasmic-reticulum-associated degradation (ERAD)quality control system tomanagethe production of triterpene saponins, widespread bioactive compounds that share a biogenic origin with sterols. An ERAD-type RING membraneanchor E3 ubiquitin ligase is co-expressed with saponin synthesis enzymes to control the activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), the rate-limiting enzyme in the supply of the ubiquitous terpene precursor isopentenyl diphosphate. Thus, unrestrained bioactive saponin accumulationis prevented and plant development and integrity secured. This control apparatus is equivalent to the ERAD system that regulates sterol synthesis in yeasts and mammals but that uses distinct E3 ubiquitin ligases, of the HMGR degradation 1 (HRD1) type, to direct destruction of HMGR. Hence, the general principles for the management of sterol and triterpene saponin biosynthesis are conserved across eukaryotes but can be controlled by divergent regulatory cues.

The Protein quality control system manages plant defence compound synthesis

Jasmonates are ubiquitous oxylipin-derived phytohormones that are essential in the regulation of many development, growth and defence processes. Across the plant kingdom, jasmonates act as elicitors of the production of bioactive secondarymetabolites that serve in defence against attackers. Knowledge of the conserved jasmonate perception and early signalling machineries is increasing, but the downstream mechanisms that regulate defence metabolism remain largely unknown. Herewe showthat, in the legumeMedicago truncatula, jasmonate recruits the endoplasmic-reticulum-associated degradation (ERAD)quality control system tomanagethe production of triterpene saponins, widespread bioactive compounds that share a biogenic origin with sterols. An ERAD-type RING membraneanchor E3 ubiquitin ligase is co-expressed with saponin synthesis enzymes to control the activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), the rate-limiting enzyme in the supply of the ubiquitous terpene precursor isopentenyl diphosphate. Thus, unrestrained bioactive saponin accumulationis prevented and plant development and integrity secured. This control apparatus is equivalent to the ERAD system that regulates sterol synthesis in yeasts and mammals but that uses distinct E3 ubiquitin ligases, of the HMGR degradation 1 (HRD1) type, to direct destruction of HMGR. Hence, the general principles for the management of sterol and triterpene saponin biosynthesis are conserved across eukaryotes but can be controlled by divergent regulatory cues.

The Protein quality control system manages plant defence compound synthesis

Jasmonates are ubiquitous oxylipin-derived phytohormones that are essential in the regulation of many development, growth and defence processes. Across the plant kingdom, jasmonates act as elicitors of the production of bioactive secondarymetabolites that serve in defence against attackers. Knowledge of the conserved jasmonate perception and early signalling machineries is increasing, but the downstream mechanisms that regulate defence metabolism remain largely unknown. Herewe showthat, in the legumeMedicago truncatula, jasmonate recruits the endoplasmic-reticulum-associated degradation (ERAD)quality control system tomanagethe production of triterpene saponins, widespread bioactive compounds that share a biogenic origin with sterols. An ERAD-type RING membraneanchor E3 ubiquitin ligase is co-expressed with saponin synthesis enzymes to control the activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), the rate-limiting enzyme in the supply of the ubiquitous terpene precursor isopentenyl diphosphate. Thus, unrestrained bioactive saponin accumulationis prevented and plant development and integrity secured. This control apparatus is equivalent to the ERAD system that regulates sterol synthesis in yeasts and mammals but that uses distinct E3 ubiquitin ligases, of the HMGR degradation 1 (HRD1) type, to direct destruction of HMGR. Hence, the general principles for the management of sterol and triterpene saponin biosynthesis are conserved across eukaryotes but can be controlled by divergent regulatory cues.

Contributions of the peroxisome and β-oxidation cycle to biotin synthesis in fungi.

The first step in the synthesis of the bicyclic rings of D-biotin is mediated by 8-amino-7-oxononanoate (AON) synthase, which catalyzes the decarboxylative condensation of l-alanine and pimelate thioester. We found that the Aspergillus nidulans AON synthase, encoded by the bioF gene, is a peroxisomal enzyme with a type 1 peroxisomal targeting sequence (PTS1). Localization of AON to the peroxisome was essential for biotin synthesis because expression of a cytosolic AON variant or deletion of pexE, encoding the PTS1 receptor, rendered A. nidulans a biotin auxotroph. AON synthases with PTS1 are found throughout the fungal kingdom, in ascomycetes, basidiomycetes, and members of basal fungal lineages but not in representatives of the Saccharomyces species complex, including Saccharomyces cerevisiae. A. nidulans mutants defective in the peroxisomal acyl-CoA oxidase AoxA or the multifunctional protein FoxA showed a strong decrease in colonial growth rate in biotin-deficient medium, whereas partial growth recovery occurred with pimelic acid supplementation. These results indicate that pimeloyl-CoA is the in vivo substrate of AON synthase and that it is generated in the peroxisome via the β-oxidation cycle in A. nidulans and probably in a broad range of fungi. However, the β-oxidation cycle is not essential for biotin synthesis in S. cerevisiae or Escherichia coli. These results suggest that alternative pathways for synthesis of the pimelate intermediate exist in bacteria and eukaryotes and that Saccharomyces species use a pathway different from that used by the majority of fungi.

1,2,3,4-Tetrahydrobenzo[h][1,6]naphthyridines as a new family of potent peripheral-to-midgorge-site inhibitors of acetylcholinesterase: synthesis, pharmacological evaluation and mechanistic studies

A series of 1,2,3,4-tetrahydrobenzo[h][1,6]naphthyridines differently substituted at positions 1, 5, and 9 have been designed from the pyrano[3,2-c]quinoline derivative 1, a weak inhibitor of acetylcholinesterase (AChE) with predicted ability to bind to the AChE peripheral anionic site (PAS), at the entrance of the catalytic gorge. Fourteen novel benzonaphthyridines have been synthesized through synthetic sequences involving as the key step a multicomponent Povarov reaction between an aldehyde, an aniline and an enamine or an enamide as the activated alkene. The novel compounds have been tested against Electrophorus electricus AChE (EeAChE), human recombinant AChE (hAChE), and human serum butyrylcholinesterase (hBChE), and their brain penetration has been assessed using the PAMPA-BBB assay. Also, the mechanism of AChE inhibition of the most potent compounds has been thoroughly studied by kinetic studies, a propidium displacement assay, and molecular modelling. We have found that a seemingly small structural change such as a double O → NH bioisosteric replacement from the hit 1 to 16a results in a dramatic increase of EeAChE and hAChE inhibitory activities (>217- and >154-fold, respectively), and in a notable increase in hBChE inhibitory activity (> 11-fold), as well. An optimized binding at the PAS besides additional interactions with AChE midgorge residues seem to account for the high hAChE inhibitory potency of 16a (IC50 = 65 nM), which emerges as an interesting anti-Alzheimer lead compound with potent dual AChE and BChE inhibitory activities.

1,2,3,4-Tetrahydrobenzo[h][1,6]naphthyridines as a new family of potent peripheral-to-midgorge-site inhibitors of acetylcholinesterase: synthesis, pharmacological evaluation and mechanistic studies

A series of 1,2,3,4-tetrahydrobenzo[h][1,6]naphthyridines differently substituted at positions 1, 5, and 9 have been designed from the pyrano[3,2-c]quinoline derivative 1, a weak inhibitor of acetylcholinesterase (AChE) with predicted ability to bind to the AChE peripheral anionic site (PAS), at the entrance of the catalytic gorge. Fourteen novel benzonaphthyridines have been synthesized through synthetic sequences involving as the key step a multicomponent Povarov reaction between an aldehyde, an aniline and an enamine or an enamide as the activated alkene. The novel compounds have been tested against Electrophorus electricus AChE (EeAChE), human recombinant AChE (hAChE), and human serum butyrylcholinesterase (hBChE), and their brain penetration has been assessed using the PAMPA-BBB assay. Also, the mechanism of AChE inhibition of the most potent compounds has been thoroughly studied by kinetic studies, a propidium displacement assay, and molecular modelling. We have found that a seemingly small structural change such as a double O → NH bioisosteric replacement from the hit 1 to 16a results in a dramatic increase of EeAChE and hAChE inhibitory activities (>217- and >154-fold, respectively), and in a notable increase in hBChE inhibitory activity (> 11-fold), as well. An optimized binding at the PAS besides additional interactions with AChE midgorge residues seem to account for the high hAChE inhibitory potency of 16a (IC50 = 65 nM), which emerges as an interesting anti-Alzheimer lead compound with potent dual AChE and BChE inhibitory activities.

Synthesis and multi-target biological profiling of a novel family of rhein derivatives as disease-modifying anti-Alzheimer agents

We have synthesized a family of rheinhuprine hybrids to hit several key targets for Alzheimer"s disease. Biological screening performed in vitro and in Escherichia coli cells has shown that these hybrids exhibit potent inhibitory activities against human acetylcholinesterase butyrylcholinesterase, and BACE-1, dual Aβ42 and tau anti-aggregating activity, and brain permeability. Ex vivo studies with the leads (+)- and ()-7e in brain slices of C57bl6 mice have revealed that they efficiently protect against the Aβ-induced synaptic dysfunction , preventing the loss of synaptic proteins and/or have a positive effect on the induction of long term potentiation. In vivo studies in APP-PS1 transgenic mice treated i.p. for 4 weeks with (+)- and ()-7e have shown a central soluble Aβ lowering effect, accompanied by an increase in the levels of mature amyloid precursor protein (APP). Thus, (+)- and ()-7e emerge as very promising disease-modifying anti-Alzheimer drug candidates.

Synthesis and multi-target biological profiling of a novel family of rhein derivatives as disease-modifying anti-Alzheimer agents

We have synthesized a family of rheinhuprine hybrids to hit several key targets for Alzheimer"s disease. Biological screening performed in vitro and in Escherichia coli cells has shown that these hybrids exhibit potent inhibitory activities against human acetylcholinesterase butyrylcholinesterase, and BACE-1, dual Aβ42 and tau anti-aggregating activity, and brain permeability. Ex vivo studies with the leads (+)- and ()-7e in brain slices of C57bl6 mice have revealed that they efficiently protect against the Aβ-induced synaptic dysfunction , preventing the loss of synaptic proteins and/or have a positive effect on the induction of long term potentiation. In vivo studies in APP-PS1 transgenic mice treated i.p. for 4 weeks with (+)- and ()-7e have shown a central soluble Aβ lowering effect, accompanied by an increase in the levels of mature amyloid precursor protein (APP). Thus, (+)- and ()-7e emerge as very promising disease-modifying anti-Alzheimer drug candidates.

First enantioselective synthesis of isagarin, a natural product isolated from Pentas longiflora Oliv.

For the first time, an enantioselective synthesis of both 1R,4S-isagarin 1a and 1S,4R-isagarin 1b was achieved starting from 1,4-dimethoxy-2-vinylnaphtalene 2. The key steps involve a Sharpless asymmetric dihydroxylation and reaction with an acetonylating pyridinium ylid.