SUMMARY1 he iron plaque on roots of Aster tripolium L. growing in waterlogged salt marsh soil adsorbed appreciable amounts of Zn and Cu,with maximum Zn/Fe and Cu/Fe ratios of 0-1. When concentrations of Zn or Cu adsorbed 'n the iron plaque are expressed as mg metal kg"' FeOOH (assuming that iron plaque consists mainly of I'eOOH), the Zn and Cu concentrations ot the iron plaque was up to 680 and up to 2900 times higher than in the surrounding sediment, respectively. The Zn concentration in red roots (with iron plaque) was higher than in white roots (without iron plaque), Zn concentrations in field sampled roots were correlated with the amount of Zn on "le roots and the Zn concentration in the soil, whereas Cu concentrations in the roots were only significantly correlated to the Cu concentration in the soil. In vitro experiments showed that red roots take up more Zn than •white roots. Measurement of Zn uptake by excised roots showed that the uptake of Zn into the xylem fluid was significantly higher in roots with 500-2000 nmol Fe cm"'' on the root surface compared to roots with less than 500 Or more than 2000 nmol Fe cm"'^ on the root surface. The results indicate that iron plaque enhances uptake of Zn ny the roots but may act as a barrier when large amounts of Fe are deposited on the root surface. The role of the "•on plaque on roots of salt marsh plants growing in soil contaminated with heavy metals is discussed
Invasive group A streptococcal (iGAS) disease cases increased in the first half of 2022 in the Netherlands, with a remarkably high proportion of emm4 isolates. Whole-genome sequence analysis of 66 emm4 isolates, 40 isolates from the pre-coronavirus disease 2019 (COVID-19) pandemic period 2009–2019 and 26 contemporary isolates from 2022, identified a novel
Streptococcus pyogenes
lineage (M4NL22), which accounted for 85 % of emm4 iGAS cases in 2022. Surprisingly, we detected few isolates of the emm4 hypervirulent clone, which has replaced nearly all other emm4 in the USA and the UK. M4NL22 displayed genetic differences compared to other emm4 strains, although these were of unclear biological significance. In publicly available data, we identified a single Norwegian isolate belonging to M4NL22, which was sampled after the isolates from this study, possibly suggesting export of M4NL22 to Norway. In conclusion, our study identified a novel S. pyogenes emm4 lineage underlying an increase of iGAS disease in early 2022 in the Netherlands and the results have been promptly communicated to public health officials.
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