Genomes of ticks display reductions, to various extents, in genetic coding for enzymes of the haem biosynthetic pathway. Here, we mined available transcriptomes of soft tick species and identified transcripts encoding only half of the enzymes involved in haem biosynthesis. Transcripts identified across most species examined were those coding for porphobilinogen synthase, coproporphyrinogen oxidase, protoporphyrinogen oxidase, and ferrochelatase. Genomic retention of porphobilinogen synthase seems to be soft tick-restricted as no such homologue has been identified in any hard tick species. Bioinformatic mining is thus strongly indicative of the lack of biochemical capacity for de novo haem biosynthesis, suggesting a requirement for dietary haem. In the hard tick Ixodes ricinus, depletion of dietary haem, i.e. serum feeding, leads to oviposition of haem-free eggs, with no apparent embryogenesis and larvae formation. In this work, we show that serum-fed Ornithodoros moubata females, unlike those of I. ricinus, laid haem-containing eggs similarly to blood-fed controls, but only by a small proportion of the serum-fed females. To enhance the effect of dietary haem depletion, O. moubata ticks were serum-fed consecutively as last nymphal instars and females. These females laid eggs with profoundly reduced haem deposits, confirming the host origin of the haem. These data confirm the ability of soft ticks to take up and allocate host haem to their eggs in order to drive reproduction of the ticks.

• MeSH
• Argasidae * MeSH
• hem MeSH
• Ixodidae * MeSH
• Ornithodoros * MeSH
• porfobilinogensynthasa MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• aminokyseliny fyziologie   MeSH
• fenotyp MeSH
• Saccharomyces cerevisiae fyziologie   MeSH

• MeSH
• léková rezistence MeSH
• mikrobiální genetika MeSH
• Mycobacterium smegmatis * metabolismus   MeSH
• streptomycin * MeSH

Fenomén trpasličích kmenů S. aureus, tzv. Small Colony Variants (SČV), je spojen s chronickými a rekurentními stafylokokovými infekcemi. Tyto fenotypové varianty se liší od kmenů S. aureus s běžným fenotypem nejčastěji velikostí kolonií, jejich morfologií, pigmentací a dalšími znaky, ale také molekulárně genetickými změnami. Příčinou vzniku SCV fenotypu je často mutace v některém z důležitých metabolických či regulačních genů, která je spojena s auxotrofií. Z klinického hlediska je významná zvýšená schopnost SCV kmenů odolávat antibiotické léčbě, zapříčiněná jednak rezistencí k určitým antibiotikům spojenou s příčinou SCV fenotypu a také se schopností těchto kmenů perzistovat uvnitř hostitelských buněk.

The phenomenon of dwarf colonies of S. aureus, the so-called small colony variants (SCVs), is associated with chronic and recurrent staphylococcal infections. Most frequently, these phenotypic variants differ from normal strains of S. aureus in colony size, morphology, pigmentation and other characteristics as well as molecular genetic changes. SCVs frequently emerge as a result of mutations in metabolically important and regulatory genes. The mutations are a cause of SCVs auxotrophy. From a clinical point of view, an increased ability of SCVs to resist antibiotic therapy and also an ability to persist within eukaryotic host cells are of importance.

• MeSH
• antibakteriální látky terapeutické užití   MeSH
• cystická fibróza farmakoterapie   mikrobiologie   MeSH
• fenotyp MeSH
• hemin MeSH
• kultivační techniky metody   statistika a číselné údaje   trendy   MeSH
• lidé MeSH
• molekulární biologie MeSH
• mutace genetika   MeSH
• stafylokokové infekce * diagnóza   etiologie   mikrobiologie   MeSH
• Staphylococcus aureus * izolace a purifikace   patogenita   MeSH
• vitamin K 3 metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH
• přehledy MeSH

Haem and iron homeostasis in most eukaryotic cells is based on a balanced flux between haem biosynthesis and haem oxygenase-mediated degradation. Unlike most eukaryotes, ticks possess an incomplete haem biosynthetic pathway and, together with other (non-haematophagous) mites, lack a gene encoding haem oxygenase. We demonstrated, by membrane feeding, that ticks do not acquire bioavailable iron from haemoglobin-derived haem. However, ticks require dietary haemoglobin as an exogenous source of haem since, feeding with haemoglobin-depleted serum led to aborted embryogenesis. Supplementation of serum with haemoglobin fully restored egg fertility. Surprisingly, haemoglobin could be completely substituted by serum proteins for the provision of amino-acids in vitellogenesis. Acquired haem is distributed by haemolymph carrier protein(s) and sequestered by vitellins in the developing oocytes. This work extends, substantially, current knowledge of haem auxotrophy in ticks and underscores the importance of haem and iron metabolism as rational targets for anti-tick interventions.

• MeSH
• fertilita MeSH
• hem metabolismus   MeSH
• klíšťata metabolismus   fyziologie   MeSH
• rozmnožování MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Actinobacteria of the acI lineage are the most abundant microbes in freshwater systems, but there are so far no pure living cultures of these organisms, possibly because of metabolic dependencies on other microbes. This, in turn, has hampered an in-depth assessment of the genomic basis for their success in the environment. Here we present genomes from 16 axenic cultures of acI Actinobacteria. The isolates were not only of minute cell size, but also among the most streamlined free-living microbes, with extremely small genome sizes (1.2-1.4 Mbp) and low genomic GC content. Genome reduction in these bacteria might have led to auxotrophy for various vitamins, amino acids and reduced sulphur sources, thus creating dependencies to co-occurring organisms (the 'Black Queen' hypothesis). Genome analyses, moreover, revealed a surprising degree of inter- and intraspecific diversity in metabolic pathways, especially of carbohydrate transport and metabolism, and mainly encoded in genomic islands. The striking genotype microdiversification of acI Actinobacteria might explain their global success in highly dynamic freshwater environments with complex seasonal patterns of allochthonous and autochthonous carbon sources. We propose a new order within Actinobacteria ('Candidatus Nanopelagicales') with two new genera ('Candidatus Nanopelagicus' and 'Candidatus Planktophila') and nine new species.

• MeSH
• Actinobacteria klasifikace   genetika   izolace a purifikace   MeSH
• biodiverzita MeSH
• DNA bakterií chemie   MeSH
• fylogeneze MeSH
• genom bakteriální * MeSH
• metabolické sítě a dráhy genetika   MeSH
• sladká voda mikrobiologie   MeSH
• zastoupení bazí MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The accumulation of glycerol is essential for yeast viability upon hyperosmotic stress. Here we show that the osmotolerant yeast Zygosaccharomyces rouxii has two genes, ZrSTL1 and ZrSTL2, encoding transporters mediating the active uptake of glycerol in symport with protons, contributing to cell osmotolerance and intracellular pH homeostasis. The growth of mutants lacking one or both transporters is affected depending on the growth medium, carbon source, strain auxotrophies, osmotic conditions and the presence of external glycerol. These transporters are localised in the plasma membrane, they transport glycerol with similar kinetic parameters and besides their expected involvement in the cell survival of hyperosmotic stress, they surprisingly both contribute to an efficient survival of hypoosmotic shock and to the maintenance of intracellular pH homeostasis under non-stressed conditions. Unlike STL1 in Sa. cerevisiae, the two Z. rouxii STL genes are not repressed by glucose, but their expression and activity are downregulated by fructose and upregulated by non-fermentable carbon sources, with ZrSTL1 being more influenced than ZrSTL2. In summary, both transporters are highly important, though Z. rouxii CBS 732(T) cells do not use external glycerol as a source of carbon.

• MeSH
• biologický transport MeSH
• delece genu MeSH
• fyziologický stres MeSH
• glycerol metabolismus   MeSH
• koncentrace vodíkových iontů MeSH
• kultivační média chemie   MeSH
• mikrobiální viabilita MeSH
• organické látky metabolismus   MeSH
• osmoregulace * MeSH
• osmotický tlak MeSH
• regulace genové exprese u hub účinky léků   MeSH
• symportéry genetika   metabolismus   MeSH
• Zygosaccharomyces genetika   růst a vývoj   metabolismus   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH