Prebiotic Dotaz Zobrazit nápovědu
Synthesis of RNA nucleobases from formamide is one of the recurring topics of prebiotic chemistry research. Earlier reports suggest that thymine, the substitute for uracil in DNA, may also be synthesized from formamide in the presence of catalysts enabling conversion of formamide to formaldehyde. In the current paper, we show that to a lesser extent conversion of uracil to thymine may occur even in the absence of catalysts. This is enabled by the presence of formic acid in the reaction mixture that forms as the hydrolysis product of formamide. Under the reaction conditions of our study, the disproportionation of formic acid may produce formaldehyde that hydroxymethylates uracil in the first step of the conversion process. The experiments are supplemented by quantum chemical modeling of the reaction pathway, supporting the plausibility of the mechanism suggested by Saladino and coworkers.
Jednou z možností pozitivního ovlivnění střevní mikrobioty je konzumace potravin bohatých na prebiotické oligosacharidy. Takovou potravinou jsou i semena sladkých odrůd lupiny bílé obsahující vysoký podíl oligosacharidů rafinózové řady (RSO). Zastoupení těchto látek se může měnit i v závislosti na stanovišti, proto bylo našim cílem stanovit množství RSO v lupině bílé pěstované v České republice. K tomuto účelu byl použit enzymatický test Raffinose/Sucrose/D-Glucose Assay Kit (Megazyme®). Průměrné množství RSO bylo 8 g/100 g lupinové mouky. Vzhledem k tomu, že dostatečnou podporu růstu probiotických bakterií v tlustém střevě zajistí dávka 1 až 2 g RSO/den, konzumace 25 g lupinové mouky denně je zcela dostačující k dosažení prebiotického efektu.
Foods rich in prebiotic oligosaccharides have a positive effect on intestinal microbiota composition. High proportion of prebiotic raffinose series oligosaccharides (RSO) is characteristic for sweet varieties of lupine. Amount of RSO is variable, dependent also on growing habitat. The aim of this study was to evaluate the presence of RSO in lupine grown in Czech Republic. Enzymatic test Raffinose/Sucrose/DGlucose Assay Kit (Megazyme®) was used. Mean content of RSO in lupine meal was 8 g/100 g. A sufficient daily intake of RSO for supporting the growth of probiotic intestinal bacteria is 1–2 g, therefore daily consumption of 25 g lupine flour is sufficient to achieve a prebiotic effect.
- Klíčová slova
- lupina bílá,
- MeSH
- Fabaceae * MeSH
- fyziologie výživy MeSH
- lidé MeSH
- oligosacharidy MeSH
- prebiotika * MeSH
- střevní mikroflóra * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
- MeSH
- cytodiagnostika MeSH
- karcinom diagnóza patologie prevence a kontrola MeSH
- kolposkopie MeSH
- králíci MeSH
- lidé MeSH
- nádory děložního čípku diagnóza patologie prevence a kontrola MeSH
- plošný screening MeSH
- prekancerózy diagnóza patologie prevence a kontrola MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- lidé MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
Prebiotic nucleotide synthesis is crucial to understanding the origins of life on Earth. There are numerous candidates for life's first nucleic acid, however, currently no prebiotic method to selectively and concurrently synthesise the canonical Watson-Crick base-pairing pyrimidine (C, U) and purine (A, G) nucleosides exists for any genetic polymer. Here, we demonstrate the divergent prebiotic synthesis of arabinonucleic acid (ANA) nucleosides. The complete set of canonical nucleosides is delivered from one reaction sequence, with regiospecific glycosidation and complete furanosyl selectivity. We observe photochemical 8-mercaptopurine reduction is efficient for the canonical purines (A, G), but not the non-canonical purine inosine (I). Our results demonstrate that synthesis of ANA may have been facile under conditions that comply with plausible geochemical environments on early Earth and, given that ANA is capable of encoding RNA/DNA compatible information and evolving to yield catalytic ANA-zymes, ANA may have played a critical role during the origins of life.
This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).
Úvod: Zlepšenie ľudského zdravia moduláciou mikrobiálnej interakcie počas všetkých fáz života je vyvíjajúci sa koncept, ktorý je čoraz dôležitejší pre spotrebiteľov, výrobcov potravín, odborníkov v oblasti zdravotnej starostlivosti a regulátorov. S rozvojom uvedených poznatkov, vedeckých dôkazov, teórií a hypotéz sa vyvíjali aj „nové“ označenia a definície základných pojmov, ktoré sú dôležité pre systémový pohľad a pochopenie významu a súčasného stavu poznatkov v tejto oblasti. Kontext: Uvádzame recentné definície základných pojmov čiastočne s ich vysvetlením, aby pomohli pediatrom lepšie sa zorientovať v rastúcom počte informácií v oblasti modulácií mikrobioty, ale tiež v rastúcom počte liečiv či výživových doplnkov, ktoré nie vždy uvádzajú relevantné a správne informácie o ich zložení a účinkoch. Viaceré z uvedených pojmov sú niekedy aj komerčne zneužívané. Záver: Pediatri, všeobecní lekári pre deti a dorast spolu s neonatológmi môžu svojimi vedomosťami a radami významne ovplyvňovať výživu novorodencov a dojčiat. K tomu neoddeliteľne patria aj základné informácie o platných definíciách a charakteristike pojmov, ktoré sa v týchto odporúčaniach používajú.
Introduction: Improving human health through the modulation of microbial interaction during all stages of life is an evolving concept that is increasingly important to consumers, food manufacturers, healthcare professionals and regulators. With the development of the aforementioned knowledge, scientific evidence, theories and hypotheses, "new" designations and definitions of basic terms were also developed, which are important for a systemic view and understanding of the meaning and current state of knowledge in this area. Context: We present recent definitions of basic terms, partly with their explanation, to help pediatricians better navigate the growing number of information in the field of microbiota modulation, but also in the growing number of drugs or nutritional supplements that do not always provide relevant and correct information about their composition and effects. Several of the mentioned terms are sometimes also commercially abused. Conclusion: Pediatricians, general practitioners for children and adolescents, together with neonatologists, can significantly influence the nutrition of newborns and infants with their knowledge and advice. Basic information about the valid definitions and characteristics of the terms used in these recommendations is integral to this.
- MeSH
- fyziologie výživy kojenců MeSH
- kojenec MeSH
- lidé MeSH
- mateřské mléko chemie MeSH
- náhražky mateřského mléka analýza normy MeSH
- oligosacharidy fyziologie metabolismus normy terapeutické užití MeSH
- potravní doplňky * klasifikace normy MeSH
- střevní mikroflóra MeSH
- synbiotika * analýza klasifikace MeSH
- terminologie jako téma MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- Publikační typ
- přehledy MeSH
Prebiotics are used for stimulating the growth of beneficial microorganisms in the gut. However, it is very difficult to find a suitable prebiotic mixture that exclusively supports the growth of beneficial microbes such as bifidobacteria and lactobacilli. We tested the effects of a prebiotic mixture in vitro by incubating it with fecal samples and in vivo by administration of the prebiotic supplement to healthy adult volunteers, followed by analysis of their fecal microbiota. The effect of the oligosaccharides on bacterial metabolism was studied by analyzing short-chain fatty acid (SCFA) production in vitro and the SCFA pattern for the stool samples of volunteers. In the in vitro test, a higher proportion of bifidobacteria (25.77%) was seen in the total bacterial population after cultivation on a prebiotic mixture than on the control medium (7.94%). The gram-negative anaerobe count significantly decreased from 8.70 to 6.40 log CFU/g (from 35.21% to 0.60%) and the Escherichia coli count decreased from 7.41 to 6.27 log CFU/g (from 1.78% to 0.44%). Administration of a prebiotic mixture in vivo (9 g of galactooligosaccharides [GOS]+1 g of maltodextrins; daily for 5 days) significantly increased the fecal bifidobacterial count from 9.45 to 9.83 log CFU/g (from 40.80% to 53.85% of total bacteria) and reduced the E. coli count from 7.23 to 6.28 log CFU/g (from 55.35% to 45.06% of total bacteria). The mixture comprising GOS and maltodextrins thus exhibited bifidogenic properties, promoting the performance of bifidobacteria by boosting their growth and inhibiting the growth of undesirable bacteria.
- MeSH
- Bifidobacterium účinky léků růst a vývoj metabolismus MeSH
- dospělí MeSH
- Escherichia coli účinky léků růst a vývoj metabolismus MeSH
- feces mikrobiologie MeSH
- fixní kombinace léků MeSH
- galaktosa farmakologie MeSH
- kyseliny mastné těkavé metabolismus MeSH
- lidé středního věku MeSH
- lidé MeSH
- oligosacharidy farmakologie MeSH
- polysacharidy farmakologie MeSH
- prebiotika * MeSH
- střeva účinky léků metabolismus mikrobiologie MeSH
- střevní mikroflóra účinky léků MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- klinické zkoušky kontrolované MeSH
- práce podpořená grantem MeSH
High-yielding and selective prebiotic syntheses of RNA and DNA nucleotides involve UV irradiation to promote the key reaction steps and eradicate biologically irrelevant isomers. While these syntheses were likely enabled by UV-rich prebiotic environment, UV-induced formation of photodamages in polymeric nucleic acids, such as cyclobutane pyrimidine dimers (CPDs), remains the key unresolved issue for the origins of RNA and DNA on Earth. Here, we demonstrate that substitution of adenine with 2,6-diaminopurine enables repair of CPDs with yields reaching 92%. This substantial self-repairing activity originates from excellent electron donating properties of 2,6-diaminopurine in nucleic acid strands. We also show that the deoxyribonucleosides of 2,6-diaminopurine and adenine can be formed under the same prebiotic conditions. Considering that 2,6-diaminopurine was previously shown to increase the rate of nonenzymatic RNA replication, this nucleobase could have played critical roles in the formation of functional and photostable RNA/DNA oligomers in UV-rich prebiotic environments.
- MeSH
- 2-aminopurin analogy a deriváty farmakologie MeSH
- adenin MeSH
- DNA účinky léků účinky záření MeSH
- nukleotidy MeSH
- nukleové kyseliny MeSH
- oprava DNA účinky léků MeSH
- prebiotika * MeSH
- pyrimidinové dimery MeSH
- RNA chemie MeSH
- simulace molekulární dynamiky MeSH
- ultrafialové záření škodlivé účinky MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The earliest proteins had to rely on amino acids available on early Earth before the biosynthetic pathways for more complex amino acids evolved. In extant proteins, a significant fraction of the 'late' amino acids (such as Arg, Lys, His, Cys, Trp and Tyr) belong to essential catalytic and structure-stabilizing residues. How (or if) early proteins could sustain an early biosphere has been a major puzzle. Here, we analysed two combinatorial protein libraries representing proxies of the available sequence space at two different evolutionary stages. The first is composed of the entire alphabet of 20 amino acids while the second one consists of only 10 residues (ASDGLIPTEV) representing a consensus view of plausibly available amino acids through prebiotic chemistry. We show that compact conformations resistant to proteolysis are surprisingly similarly abundant in both libraries. In addition, the early alphabet proteins are inherently more soluble and refoldable, independent of the general Hsp70 chaperone activity. By contrast, chaperones significantly increase the otherwise poor solubility of the modern alphabet proteins suggesting their coevolution with the amino acid repertoire. Our work indicates that while both early and modern amino acids are predisposed to supporting protein structure, they do so with different biophysical properties and via different mechanisms.
- MeSH
- aminokyseliny * chemie MeSH
- prebiotika * MeSH
- proteiny chemie MeSH
- sbalování proteinů MeSH
- Publikační typ
- časopisecké články MeSH
Představujeme kazuistiku mladého muže s atopickým ekzémem/dermatitidou a polyvalentní potravinovou alergií, klinicky projevenou převážně zhoršováním průběhu atopické dermatitidy po většině potravin. Multiplexovou komponentovou diagnostikou (metodou ALEX –Allergy Explorer)jsme vyšetřili specifické IgE a klasická celková léčba byla doplněna o kombinaci prebiotika s enterosorbentem. Zavedení této léčby vedlo k velmi dobrému okamžitému klinickému efektu.
We present acase report of ayoung man with atopic eczema/dermatitis and polyvalent food allergy, clinically manifested predominantly with worsening of the course of atopic dermatitis, following aconsumption of most food. We used the ALEX (Allergy Explorer) multiplex method to analyse specific IgE, and the usual overall treatment was supplemented with administration of prebiotics and enterosorbents. Introduction of this treatment resulted in very good and immediate clinical effect.
- Klíčová slova
- Atopona,
- MeSH
- atopická dermatitida farmakoterapie imunologie MeSH
- lidé MeSH
- potravinová alergie * farmakoterapie imunologie MeSH
- prebiotika MeSH
- výsledek terapie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
