Herstel Grote stuifzanden : verslag veldwerkplaats Droog zandlandschap Loonse en Drunense Duinen, 24 juni 2009

Welke functies wil je toekennen aan stuifzandgebied? Wil je er een natuurgebied gericht op de pioniersstadia met lichenensteppes en zo min mogelijk verstoring? Of wil je een gebied voor recreanten en wil je net zoals hier in de Loonse en Drunense duinen anderhalf miljoen mensen per jaar kunnen opvangen? Of is het doel om er een soort geo-park van te maken om het stuifzandlandschap te kunnen bewaren

Effectgerichte maatregelen voor het herstel en beheer van stuifzanden

Onderzoek naar het functioneren van stuifzanden onder gewijzigde abiotische condities en naar beheer en herstel van klein- en grootschalige stuifzandlandschappen. Waarin bijdragen: Bosschap, Stichting Bargerveen, Radboud Universiteit, Universiteit Amsterdam, SOVON, Vlinderstichting, Alterra en Stichting Geomofologie en Landschap. Het is een vervolg op Preadvies stuifzanden (Bakker, 2003)

Unravelling the phylogenetic relationships of lichenised fungi in Dothideomyceta

We present a revised phylogeny of lichenised Dothideomyceta (Arthoniomycetes and Dothideomycetes) based on a combined data set of nuclear large subunit (nuLSU) and mitochondrial small subunit (mtSSU) rDNA data. Dothideomyceta is supported as monophyletic with monophyletic classes Arthoniomycetes and Dothideomycetes; the latter, however, lacking support in this study. The phylogeny of lichenised Arthoniomycetes supports the current division into three families: Chrysothrichaceae (Chrysothrix), Arthoniaceae (Arthonia s. l., Cryptothecia, Herpothallon), and Roccellaceae (Chiodecton, Combea, Dendrographa, Dichosporidium, Enterographa, Erythrodecton, Lecanactis, Opegrapha, Roccella, Roccellographa, Schismatomma, Simonyella). The widespread and common Arthonia caesia is strongly supported as a (non-pigmented) member of Chrysothrix. Monoblastiaceae, Strigulaceae, and Trypetheliaceae are recovered as unrelated, monophyletic clades within Dothideomycetes. Also, the genera Arthopyrenia (Arthopyreniaceae) and Cystocoleus and Racodium (Capnodiales) are confirmed as Dothideomycetes but unrelated to each other. Mycomicrothelia is shown to be unrelated to Arthopyrenia s.str., but is supported as a monophyletic clade sister to Trypetheliaceae, which is supported by hamathecium characters. The generic concept in several groups is in need of revision, as indicated by non-monophyly of genera, such as Arthonia, Astrothelium, Cryptothecia, Cryptothelium, Enterographa, Opegrapha, and Trypethelium in our analyses

A Novel Extracytoplasmic Function (ECF) Sigma Factor Regulates Virulence in Pseudomonas aeruginosa

Next to the two-component and quorum sensing systems, cell-surface signaling (CSS) has been recently identified as an important regulatory system in Pseudomonas aeruginosa. CSS systems sense signals from outside the cell and transmit them into the cytoplasm. They generally consist of a TonB-dependent outer membrane receptor, a sigma factor regulator (or anti-sigma factor) in the cytoplasmic membrane, and an extracytoplasmic function (ECF) sigma factor. Upon perception of the extracellular signal by the receptor the ECF sigma factor is activated and promotes the transcription of a specific set of gene(s). Although most P. aeruginosa CSS systems are involved in the regulation of iron uptake, we have identified a novel system involved in the regulation of virulence. This CSS system, which has been designated PUMA3, has a number of unusual characteristics. The most obvious difference is the receptor component which is considerably smaller than that of other CSS outer membrane receptors and lacks a β-barrel domain. Homology modeling of PA0674 shows that this receptor is predicted to be a bilobal protein, with an N-terminal domain that resembles the N-terminal periplasmic signaling domain of CSS receptors, and a C-terminal domain that resembles the periplasmic C-terminal domains of the TolA/TonB proteins. Furthermore, the sigma factor regulator both inhibits the function of the ECF sigma factor and is required for its activity. By microarray analysis we show that PUMA3 regulates the expression of a number of genes encoding potential virulence factors, including a two-partner secretion (TPS) system. Using zebrafish (Danio rerio) embryos as a host we have demonstrated that the P. aeruginosa PUMA3-induced strain is more virulent than the wild-type. PUMA3 represents the first CSS system dedicated to the transcriptional activation of virulence functions in a human pathogen

Stuifzand zeven op het Deelensche Zand: Proeven met zeefmachine in vergrast stuifzand

Op het Deelensche Zand (gelegen binnen het Nationaal Park De Hoge Veluwe) is in 2001 een stuifzandreiniger ingezet om een vergrast stuifzand weer geschikt te maken voor het zich opnieuw vestigen van korstmossen en voor de typische bewoners van korstmosrijke buntgrassteppen, zoals de blauwvleugelsprinkhaan, de heivlinder en de kleine heivlinder. Hoe deze ingrepen uitwerken op de vegetatie, de flora en de fauna is daarna tot in 2008 gevolgd