Diatom and microarthropod communities of three airfields in Estonia – Their differences and similarities and possible linkages to airfield properties

Even though airfields, which are often anthropologically modified natural areas, are continuously influenced by human activities, their soils are still dynamic ecosystems containing various habitats for microscopic groups of organisms which are often ignored. In this exploratory study, the microarthropod fauna, Collembola (Hexapoda) and oribatid mites (Acari: Oribatida), and diatom (Bacillariophyta) flora were identified in three Estonian airfields, both runway sides and snow-melting sites were investigated. The communities of these airfields shared approximately 10–60% of the species belonging to each studied bioindicator group. The shared species were generally characteristic of a broad habitat spectrum. Communities were also characterized based on their species richness and diversity and in relation to location and the purpose of different airfield areas (e.g. snow-melting sites vs. runway sides). Also, species indicative of a specific airfield or purpose of the area within the airfield were identified using Indicator Species Analysis. Some possible linkages between airfield properties and communities,  e.g. airfield that had highest pollutant concentrations had also maintained high diversity and species richness, were noted. Despite the contamination levels the airfield soils had still maintained a functioning soil ecosystem

pH-induced structural change in a sodium/proton antiporter from Methanococcus jannaschii

Na(+)/H(+) antiporters are pH-dependent membrane transport proteins that maintain the homeostasis of H(+) and Na(+) in living cells. MjNhaP1 from Methanococcus jannaschii, a hyperthermophilic archaeon that grows optimally at 85°C, was cloned and expressed in Escherichia coli. Two-dimensional crystals were obtained from purified protein at pH 4. Electron cryomicroscopy yielded an 8 Å projection map. Like the related E. coli antiporter NhaA, MjNhaP1 is a dimer, but otherwise the structures of the two antiporters differ significantly. The map of MjNhaP1 shows elongated densities in the centre of the dimer and a cluster of density peaks on either side of the dimer core, indicative of a bundle of 4–6 membrane-spanning helices. The effect of pH on the structure of MjNhaP1 was studied in situ. A major change in density distribution within the helix bundle, and a ∼2 Å shift in the position of the helix bundle relative to the dimer core occurred at pH 6 and above. The two conformations at low and high pH most likely represent the closed and open states of the antiporter

Oribatid mite (Acari: Oribatida) communities of urban brownfields in Tallinn, Estonia, and their potential as bioindicators of wasteland successional stage

Vacht, Piret, Niglas, Helin, Kuu, Annely, Koff, Tiiu, Kutti, Sander, Raamets, Jane (2019): Oribatid mite (Acari: Oribatida) communities of urban brownfields in Tallinn, Estonia, and their potential as bioindicators of wasteland successional stage. Acarologia 59 (1): 26-32, DOI: 10.24349/acarologia/2019431

Diatom and microarthropod communities of three airfields in Estonia – their differences and similarities and possible linkages to airfield properties

Even though airfields, which are often anthropologically modified natural areas, are continuously influenced by human activities, their soils are still dynamic ecosystems containing various habitats for microscopic groups of organisms which are often ignored. In this exploratory study, the microarthropod fauna, Collembola (Hexapoda) and oribatid mites (Acari: Oribatida), and diatom (Bacillariophyta) flora were identified in three Estonian airfields, both runway sides and snow-melting sites were investigated. The communities of these airfields shared approximately 10-60% of the species belonging to each studied bioindicator group. The shared species were generally characteristic of a broad habitat spectrum. Communities were also characterized based on their species richness and diversity and in relation to location and the purpose of different airfield areas (e.g. snow-melting sites vs. runway sides). Also, species indicative of a specific airfield or purpose of the area within the airfield were identified using Indicator Species Analysis. Some possible linkages between airfield properties and communities, e.g. airfield that had highest pollutant concentrations had also maintained high diversity and species richness, were noted. Despite the contamination levels the airfield soils had still maintained a functioning soil ecosystem