Acanthamoeba is known to interact with a plethora of microorganisms such as bacteria, fungi and viruses. In these interactions, the amoebae can be predatory in nature, transmission vehicle or an incubator. Amoebae consume microorganisms, especially bacteria, as food source to fulfil their nutritional needs by taking up bacteria through phagocytosis and lysing them in phagolysosomes and hence play an eminent role in the regulation of bacterial density in the nature and accountable for eradication of around 60% of the bacterial population in the environment. Acanthamoeba can also act as a "Trojan horse" for microbial transmission in the environment. Additionally, Acanthamoeba may serve as an incubator-like reservoir for microorganisms, including those that are pathogenic to humans, where the microorganisms use amoebae's defences to resist harsh environment and evade host defences and drugs, whilst growing in numbers inside the amoebae. Furthermore, amoebae can also be used as a "genetic melting pot" where exchange of genes as well as adaptation of microorganisms, leading to higher pathogenicity, may arise. Here, we describe bacteria, fungi and viruses that are known to interact with Acanthamoeba spp.
Acanthamoebae success as human pathogens is largely due to the highly resistant cysts which represent a crucial problem in treatment of Acanthamoeba infections. Hence, the study of cyst wall composition and encystment play an important role in finding new therapeutic strategies. For the first time, we detected high activity of cytoskeletal elements - microtubular networks and filamentous actin, in late phases of encystment. Cellulose fibrils - the main components of endocyst were demonstrated in inter-cystic space, and finally in the ectocyst, hereby proving the presence of cellulose in both layers of the cyst wall. We detected clustering of intramembranous particles (IMPs) and their density alterations in cytoplasmic membrane during encystment. We propose a hypothesis that in the phase of endocyst formation, the IMP clusters represent cellulose microfibril terminal complexes involved in cellulose synthesis that after cyst wall completion are reduced. Cyst wall impermeability, due largely to a complex polysaccharide (glycans, mainly cellulose) has been shown to be responsible for Acanthamoeba biocide resistance and cellulose biosynthesis pathway is suggested to be a potential target in treatment of Acanthamoeba infections. Disruption of this pathway would affect the synthesis of cyst wall and reduce considerably the resistance to chemotherapeutic agents.
- MeSH
- Acanthamoeba izolace a purifikace metabolismus ultrastruktura MeSH
- amébiáza parazitologie MeSH
- buněčná membrána metabolismus ultrastruktura MeSH
- buněčná stěna metabolismus ultrastruktura MeSH
- celulosa metabolismus MeSH
- cytoskelet metabolismus ultrastruktura MeSH
- elektronová mikroskopie MeSH
- konfokální mikroskopie MeSH
- lidé MeSH
- mikrotubuly metabolismus ultrastruktura MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Arbuscular mycorrhizal (AM) fungi can significantly contribute to plant nitrogen (N) uptake from complex organic sources, most likely in concert with activity of soil saprotrophs and other microbes releasing and transforming the N bound in organic forms. Here, we tested whether AM fungus (Rhizophagus irregularis) extraradical hyphal networks showed any preferences towards certain forms of organic N (chitin of fungal or crustacean origin, DNA, clover biomass, or albumin) administered in spatially discrete patches, and how the presence of AM fungal hyphae affected other microbes. By direct 15N labeling, we also quantified the flux of N to the plants (Andropogon gerardii) through the AM fungal hyphae from fungal chitin and from clover biomass. The AM fungal hyphae colonized patches supplemented with organic N sources significantly more than those receiving only mineral nutrients, organic carbon in form of cellulose, or nothing. Mycorrhizal plants grew 6.4-fold larger and accumulated, on average, 20.3-fold more 15N originating from the labeled organic sources than their nonmycorrhizal counterparts. Whereas the abundance of microbes (bacteria, fungi, or Acanthamoeba sp.) in the different patches was primarily driven by patch quality, we noted a consistent suppression of the microbial abundances by the presence of AM fungal hyphae. This suppression was particularly strong for ammonia oxidizing bacteria. Our results indicate that AM fungi successfully competed with the other microbes for free ammonium ions and suggest an important role for the notoriously understudied soil protists to play in recycling organic N from soil to plants via AM fungal hyphae.
- MeSH
- Acanthamoeba metabolismus MeSH
- amoniak metabolismus MeSH
- Andropogon růst a vývoj metabolismus mikrobiologie MeSH
- Bacteria metabolismus MeSH
- dusík metabolismus MeSH
- hyfy metabolismus MeSH
- mykorhiza metabolismus MeSH
- organické látky metabolismus MeSH
- oxidace-redukce MeSH
- Publikační typ
- časopisecké články MeSH
