Free-living amoebae (FLA) are protozoa that can be found in water networks where they prey on bacteria within biofilms. Most bacteria are digested rapidly by phagocytosis, however some are able to survive within amoebae and some are even able to multiply, as it is the case for Legionella pneumophila. These resisting bacteria are a potential health problem as they could also resist to macrophage phagocytosis. Several publications already reported intra-amoebal bacteria but the methods of identification did not allow metagenomic analysis and are partly based on co-culture with one selected amoebal strain. The aim of our study was to conduct a rRNA-targeted metagenomic analysis on amoebae and intra-amoebal bacteria found in drinking water network, to provide the first FLA microbiome in environmental strains. Three sites of a water network were sampled during four months. Culturable FLA were isolated and total DNA was prepared, allowing purification of both amoebal and bacterial DNA. Metagenomic studies were then conducted through 18S or 16S amplicons sequencing. Hartmannella was by far the most represented genus of FLA. Regarding intra-amoebal bacteria, 54 genera were identified, among which 21 were newly described intra-amoebal bacteria, underlying the power of our approach. There were high differences in bacterial diversity between the three sites. Several genera were highly represented and/or found at least in two sites, underlying that these bacteria could be able to multiply within FLA. Our method is therefore useful to identify FLA microbiome and could be applied to other networks to have a more comprehensive view of intra-amoebal diversity. 相似文献
The copper‐catalyzed C(sp2) H trifluoromethylation of N,N‐disubstituted hydrazones using the Togni reagent is demonstrated to proceed efficiently for aliphatic aldehyde‐derived substrates. The success of the reactions relied on the choice of the N,N‐diphenylamino group as the terminal hydrazone amino group where N,N‐dialkylamino groups were preferred for (hetero)aromatic aldehyde‐derived substrates. In addition, the trifluoromethylated N‐arylhydrazones are shown to be ideal substrates for Fischer indole synthesis allowing a straightforward, three‐step access to 2‐trifluoromethylindole derivatives from simple aldehydes.
Retrogradation rate and extent were determined by differential scanning calorimetry and rheology measurements on 40% dry matter gels made from pea, modified waxy maize, rice, waxy rice, wheat, manioc, potato and microwaved irradiated potato starches. As a result, each starch retrogrades differently, depending also on the measurement technique. Nevertheless, potato and pea starches seem to be the most sensitive and the waxy and modified waxy types are the least sensitive to retrogradation. 相似文献
In this paper, a novel phase-locked loop (PLL) architecture with multiple charge pumps, which is used to design a fast-locking
PLL and a low-phase-noise PLL, is proposed. The effective capacitance and resistance of the loop filter in terms of voltage
is scaled up/down according to the locking status by controlling the magnitude and direction of the charge pump current. Two
PLLs, one with a fast-locking characteristic and the other with a low-phase-noise characteristic, are designed and fabricated
in a 0.35-μm CMOS process based on the proposed architecture. The fast-locking PLL has a locking time of less than 6 μs and
a phase noise of −90.45 dBc/Hz at 1 MHz offset. The low-phase-noise PLL has a locking time of 25 μs, a phase noise of −105.37 dBc/Hz
at 1 MHz offset, and a reference spur of −50 dBc. Both PLLs have an 851.2 MHz output frequency. 相似文献