Synthesis of Dehydrodipeptide and N-ethyl-dehydrodipeptide Derivatives with an α-Aminoisobutyric Acid Residue

Several dipeptides with an N-benzyloxycarbonyl or an N-(tert-butyloxycarbonyl) α-aminoisobutyric acid residue and a β-hydroxyamino acid methyl ester were subjected to dehydration to form dehydrodipeptide derivatives. N-Ethylation of these dipeptides using triethyloxonium tetrafluoroborate with potassium tert-butoxide as auxiliary base led to complex mixtures that failed to render pure products. However, when the 4-nitrophenylsulfonyl protecting group was substituted for the benzyloxycarbonyl or tert-butyloxycarbonyl groups and N,N-diisopropylethylamine was substituted for potassium tert-butoxide, the dehydrodipeptide derivatives were selectively N-alkylated at the amino terminal nitrogen in fair to high yields. Alternatively, N-ethylation can be carried out prior to dehydration. Thus, through a combination of dehydration and N-ethylation procedures, it was possible to obtain dipeptides with α-aminoisobutyric acid and dehydroamino acid residues, which are N-alkylated at the amino terminal nitrogen.Foundation for Science and Technology (FCT) – Portugal and Fundo Europeu de Desenvolvimento Regional (FEDER) for financial support to Chemistry Centre of University of Minho. The NMR spectrometer Bruker Avance II+ 400 is part of the National NMR Network and was purchased in the framework of the National Program for Scientific Re-equipment; contract REDE/1517/RMN/2005, with funds from POCI 2010, FEDER and FCT.info:eu-repo/semantics/publishedVersio

Ribeiria pholadiformis Sharpe in Ribeiro (Rostroconchia): história do estudo, localidade e unidade-tipo e a coleção topotípica inédita do Museu Geológico de Portugal

ABSTRACT: Ribeiria pholadiformis Sharpe in Ribeiro, the type-species of Ribeirioida (Rostroconcha), was erected almost 170 years ago, based on portuguese fossils from the Middle Ordovician of the Buçaco Syncline. In this paper, we review the history of the study of this species and clarify the type-locality and unit for this taxon: the Cácemes Group (Darriwilian) in the Palheiros stream section (Penacova). The reconstitution of Sharpe’s original label led to discover that one of the paralectotypes is the external mould of the lectotype, being this specimen now divided between the Geological Survey Museum, Keyworth (the latter) and the Natural History Museum, London (the former). Furthermore, we report an unpublished collection of 25 specimens of topotypic material, gathered during the 19th century under the guidance of Nery Delgado, deposited in the Geological Museum of Portugal. Its study will allow assessing the morphological variability of the species for the first time.RESUMO: Ribeiria pholadiformis Sharpe in Ribeiro, a espécie-tipo de Ribeirioida (Rostroconcha), foi definida há quase 170 anos com base em fósseis portugueses do Ordovícico Médio do Sinclinal de Buçaco. Neste artigo revemos a história do estudo desta espécie e esclarecemos qual a localidade e unidade-tipo: o Grupo Cácemes (Darriwiliano) no setor da ribeira de Palheiros (Penacova). A reconstituição da etiqueta original de Sharpe permitiu descobrir que um dos paralectótipos é o molde externo do lectótipo, estando este espécime agora dividido entre duas instituições: o Natural History Museum, Londres (o primeiro) e o Geological Survey Museum, Keyworth (o segundo). Adicionalmente, damos a conhecer a constituição da coleção inédita de material topotípico de R. pholadiformis do Museu Geológico de Portugal, constituída por 25 exemplares recolhidos durante a segunda metade do século XIX sob a orientação de Nery Delgado. O seu estudo permitirá avaliar a variabilidade morfológica da espécie pela primeira vez.info:eu-repo/semantics/publishedVersio

The effect of phosphate-solubilizing rhizobacteria on Zea mays growth on P-deficient soils

P-deficiency in soils is a limiting factor for plant growth. Several phosphate-solubilizing rhizobacteria (PSB) were used to enhance growth of Zea maysgrowing in a P-deficient soil. Strains were screened for their ability to solubilize P and to produce plant growth promoting (PGP) substances. The best-P solubilizing strains Rhodococcus sp. EC35, Pseudomonas sp. EAV and Arthrobacter nicotinovoransEAPAA were inoculated in maize growing in P-deficient soils without P fertilization and amended with soluble (KH2PO4) and insoluble P (Ca3(PO4)2). Results showed that PSB significantly enhanced Z. mays biomass production in all Ptreatments. Without P fertilization, bacterial inoculation increased plant dry biomass by ca. 20%, while under soluble P conditions the enhancement was higher. Pseudomonas sp. EAV was the strain that better performed improving rootand shoot biomass by 104% and 60%, respectively. In soils amended with insoluble P, plant biomass was also positive influenced by bacterial inoculation. Plant growth enhancement seems to be related not only to Psolubilization but also to other PGP traits, such as IAA and ACC-deaminase. This work shows that PSB may be used as bioinoculants and consequently constitute an attractive alternative to the phosphatic fertilizers amendments used to improve crop production

Plant growth promoting potential of rhizobacteria isolated from a contaminated area

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Synthesis of N-alkyl-C α, α-dimethylglycine derivatives

The application of trialkyloxonium tetrafluoroborates for N-alkylation of the nonnatural amino acid Cα, α-dimethylglycine is described. Several methyl esters of dimethylglycine protected with different amine protecting groups were subject to N-ethylation or N-methylation with triethyloxonium tetrafluoroborate or trimethyloxonium tetrafluoroborate, respectively. The corresponding N-akyl-Cα, α-dimethylglycine derivatives were obtained in good to high yields. Removal of the methyl ester rendered amino acid derivatives ready for application in peptide synthesis.Foundation for Science and Technology (FCT) – Portugal and Fundo Europeu de Desenvolvimento Regional (FEDER) for financial support to Chemistry Centre of University of Minho. The NMR spectrometer Bruker Avance II+ 400 is part of the National NMR Network and was purchased in the framework of the National Program for Scientific Re-equipment; contract REDE/1517/RMN/2005, with funds from POCI 2010, FEDER and FCT.info:eu-repo/semantics/publishedVersio

Insights into nanomedicine for head and neck cancer diagnosis and treatment

Head and neck cancers rank sixth among the most common cancers today, and the survival rate has remained virtually unchanged over the past 25 years, due to late diagnosis and ineffective treatments. They have two main risk factors, tobacco and alcohol, and human papillomavirus infection is a secondary risk factor. These cancers affect areas of the body that are fundamental for the five senses. Therefore, it is necessary to treat them effectively and non-invasively as early as possible, in order to do not compromise vital functions, which is not always possible with conventional treatments (chemotherapy or radiotherapy). In this sense, nanomedicine plays a key role in the treatment and diagnosis of head and neck cancers. Nanomedicine involves using nanocarriers to deliver drugs to sites of action and reducing the necessary doses and possible side effects. The main purpose of this review is to give an overview of the applications of nanocarrier systems to the diagnosis and treatment of head and neck cancer. Herein, several types of delivery strategies, radiation enhancement, inside-out hyperthermia, and theragnostic approaches are addressed.info:eu-repo/semantics/publishedVersio

MS-1 magA: Revisiting Its Efficacy as a Reporter Gene for MRI

Bacterial genes involved in the biomineralization of magnetic nanoparticles in magnetotactic bacteria have recently been proposed as reporters for magnetic resonance imaging (MRI). In such systems, the expression of the bacterial genes in mammalian cells purportedly leads to greater concentrations of intracellular iron or the biomineralization of iron oxides, thus leading to an enhancement in relaxation rate that is detectable via MRI. Here, we show that the constitutive expression of the magA gene from Magnetospirillum magnetotacticum is tolerated by human embryonic kidney (HEK) cells but induces a strong toxic effect in murine mesenchymal/stromal cells and kidney-derived stem cells, severely restricting its effective use as a reporter gene for stem cells. Although it has been suggested that magA is involved in iron transport, when expressed in HEK cells, it does not affect the transcription of endogenous genes related to iron homeostasis. Furthermore, the magA -induced enhancement in iron uptake in HEK cells is insignificant, suggesting this gene is a poor reporter even for cell types that can tolerate its expression. We suggest that the use of magA for stem cells should be approached with caution, and its efficacy as a reporter gene requires a careful assessment on a cell-by-cell basis

The effect of bioinoculants on grapevine development

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Dissolved oxygen effect on microbial lipids production by Yarrowia lipolytica from volatile fatty acids

Volatile fatty acids (VFAs) can be obtained from organic wastes through acidogenic fermentation and the yeast Yarrowia lipolytica can use those VFAs for the biosynthesis of lipids. Oxygen is an important factor of the bioconversion process of VFAs into microbial lipids by Y. lipolytica, thus the effect of oxygenation was evaluated in batch cultures of the yeast for two different strains, varying the stirring and air flow rates. The increase of dissolved oxygen concentration improved lipid production by Y. lipolytica W29 and Y. lipolytica NCYC 2904 in glucose and VFAs (acetate, propionate and butyrate) medium. The strain NCYC 2904 accumulated higher intracellular lipids (22%, w/w) than strain W29 (12%, w/w) with differences in lipids composition. Lipids of strain W29 were mainly composed by linoleic acid (up to 47%) and oleic acid (up to 31%) and NCYC 2904 accumulated predominantly oleic acid (around 56%). For both strains, the unsaturated fraction (> 70%) exceeded the saturated one. Since fatty acid composition in Y. lipolytica are similar to common vegetable oils (usually used for biodiesel production), these lipids are a potential feedstock for biofuels production.Projects TUBITAK/0009/2014; UID/BIO/04469/2019, grant SFRH/BD/129592/2017. BioTecNorte (NORTE-01-0145-FEDER000004).info:eu-repo/semantics/publishedVersio

Bioconversion of volatile fatty acids into microbial lipids by Yarrowia lipolytica

Volatile fatty acids (VFAs) are short chain fatty acids that can be obtained from organic wastes through acidogenic fermentation and can be used as carbon source for microbial lipids production. The bioconversion of acetate, propionate and butyrate into microbial lipids by Yarrowia lipolytica W29 was evaluated, and the yeast shown the ability to grow using VFA as carbon source and accumulate lipids intracellularly (around 5 % of dry cell mass). The addition of a co-substrate (glucose or glycerol) to VFA-based medium led to an enhancement of cellular growth and lipid content of the cells. The highest lipids concentration of around 1 g/L was obtained in batch cultures carried out with a mixture of VFAs and glycerol. Notwithstanding the low lipid content obtained in this work, Y. lipolytica demonstrated the ability to metabolize VFAs and convert them to microbial lipids, which can be used for biodiesel production.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the project TÜBITAK 2014 (TUBITAK/0009/2014) and of the strategic funding of UID/BIO/04469 unit and COMPETE 2020 (POCI-01-0145-FEDER006684), Post-Doctoral grant (SFRH/BPD/101034/2014), Doctoral grant (SFRH/BD/129592/2017) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio