Microbiology of diverse acidic and non-acidic microhabitats within a sulfidic ore mine

A wide variety of microhabitats within the extremely acidic abandoned underground copper mine Zlaté Hory (Czech Republic) was investigated. SSU rDNA libraries were analyzed from 15 samples representing gossan, sulfide-leaching environments in the oxidation zone, and acidic water springs in the mine galleries. Microbial analyses were extended by analyses of chemical composition of water and solid phases and identification of arising secondary minerals. The microbial communities of the three main classes of microenvironments differed in almost every aspect. Among others, ecological partitioning of Acidithiobacillus ferrooxidans and the recently described A. ferrivorans was observed. Distinct types of communities inhabiting the water springs were detected. The more extreme springs (pH?<3, conductivity?>2?mS/cm) were inhabited by “Ferrovum” spp. and A. ferrivorans, whereas Gallionella sp. dominated the less extreme ones. A new role for gossan in the extremely acidic ecosystem is proposed. This zone was inhabited by a large diversity of neutrophilic heterotrophs that appeared to be continuously washed out to the acidic environments localized downstream. Five species originating in gossan were found in several acidic habitats. Here they can survive and probably serve as scavengers of dead biomass, particularly from chemoautotrophic growths. No such process has been described from acidic mine environments so far.     

The last population of the Woodland Brown butterfly (<Emphasis Type="Italic">Lopinga achine</Emphasis>) in the Czech Republic: habitat use,demography and site management

The distribution of Lopinga achine (Lepidoptera Nymphalidae, Satyrinae) in the Czech Republic has declined from thirty grid squares before 1950 to just one extant population, restricted to a single area of deciduous woodland. A review of historical sites shows that this species used to occur in various types of deciduous woodland with a relatively sparse canopy maintained by coppicing and/or grazing. The extant population inhabits mature woodland with a mean canopy cover of 60% (quartiles 50% and 65%), sparse shrubs and a species-rich herb layer containing plant species requiring dry, warm and nutrient-poor conditions. The larval host plants are the fine-leafed sedges, Carex fritschii and C. michelii. In 2006, the total population contained about 10,000 adults but this may be an over-estimate, biased by male behaviour. Measurements of adult mobility, well approximated by an inverse-power function, suggested that all existing colonies are interconnected by dispersal. Continuing existence of the population depends on two conditions; nutrient-poor conditions for a diverse ground flora and a sparse tree canopy. While canopy closure is gradually increasing, the herb layer is threatened by soil enrichment due to the demise of traditional grazing, litter raking and grass mowing in woodlands. Any future management to favour Lopinga achine should include both measures to maintain a sparse canopy and measures to export biomass, such as raking or mowing of ground flora or, preferably, re-establishment of grazing. An erratum to this article can be found at     

Diversity, evolution and molecular systematics of the psalteriomonadidae, the main lineage of anaerobic/microaerophilic heteroloboseans (excavata: discoba)

We isolated and cultivated 31 strains of free-living heterolobosean flagellates and amoebae from freshwater, brackish, and marine sediments with low concentrations of oxygen. Phylogenetic analysis of small subunit (SSU) rDNA showed that the strains constitute a single clade, the Psalteriomonadidae. According to combined light-microscopic morphology plus molecular phylogeny, our isolates belong to seven species and five genera, from which three species and two genera are new. In addition, previously described anaerobic species Percolomonas descissus and Vahlkampfia anaerobica are transferred to the Psalteriomonadidae. We identified a flagellate stage of Monopylocystis visvesvarai which was reported to produce only amoebae. Two environmental sequences previously obtained from acidic environments belong to the Psalteriomonadidae as well, suggesting a broad ecological importance of the Psalteriomonadidae. The ultrastructure of two psalteriomonadid species was also studied. Unifying features of the Psalteriomonadidae are acristate mitochondrial derivates, flagellates with a ventral groove and four flagella, and a harp-like structure in the mastigont. A new overall classification of the Psalteriomonadidae is proposed. Our data show that the Psalteriomonadidae are much more diverse than previously thought and constitute the main anaerobic lineage within the Heterolobosea.     

Inhibition of late endosomal maturation restores Wnt secretion in Caenorhabditis elegans vps-29 retromer mutants

Secretion of Wnt proteins is mediated by the Wnt sorting receptor Wls, which transports Wnt from the Golgi to the cell surface for release. To maintain efficient Wnt secretion, Wls is recycled back to the trans-Golgi network (TGN) through a retromer dependent endosome to TGN retrieval pathway. It has recently been shown that this is mediated by an alternative retromer pathway in which the sorting nexin SNX3 interacts with the cargo-selective subcomplex of the retromer to sort Wls into a retrieval pathway that is morphologically distinct from the classical SNX-BAR dependent retromer pathway. Here, we investigated how sorting of Wls between the two different retromer pathways is specified. We found that when the function of the cargo-selective subcomplex of the retromer is partially disrupted, Wnt secretion can be restored by interfering with the maturation of late endosomes to lysosomes. This leads to an accumulation of Wls in late endosomes and facilitates the retrieval of Wls through a SNX-BAR dependent retromer pathway. Our results are consistent with a model in which spatial separation of the SNX3 and SNX-BAR retromer complexes along the endosomal maturation pathway as well as cargo-specific mechanisms contribute to the selective retrieval of Wls through the SNX3 retromer pathway.     

The ultrastructure of the midgut epithelium in millipedes (Myriapoda,Diplopoda)

The midgut epithelia of the millipedes Polyxenus lagurus, Archispirostreptus gigas and Julus scandinavius were analyzed under light and transmission electron microscopies. In order to detect the proliferation of regenerative cells, labeling with BrdU and antibodies against phosphohistone H3 were employed. A tube-shaped midgut of three millipedes examined spreads along the entire length of the middle region of the body. The epithelium is composed of digestive, secretory and regenerative cells. The digestive cells are responsible for the accumulation of metals and the reserve material as well as the synthesis of substances, which are then secreted into the midgut lumen. The secretions are of three types – merocrine, apocrine and microapocrine. The oval or pear-like shaped secretory cells do not come into contact with the midgut lumen and represent the closed type of secretory cells. They possess many electron-dense granules (J. scandinavius) or electron-dense granules and electron-lucent vesicles (A. gigas, P. lagurus), which are accompanied by cisterns of the rough endoplasmic reticulum. The regenerative cells are distributed individually among the basal regions of the digestive cells. The proliferation and differentiation of regenerative cells into the digestive cells occurred in J. scandinavius and A. gigas, while these processes were not observed in P. lagurus. As a result of the mitotic division of regenerative cells, one of the newly formed cells fulfills the role of a regenerative cell, while the second one differentiates into a digestive cell. We concluded that regenerative cells play the role of unipotent midgut stem cells.     

Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA,alpha-tubulin and HSP90 genes: Implications for the evolutionary history of the double karyomastigont of diplomonads

Background  

Fornicata is a relatively recently established group of protists that includes the diplokaryotic diplomonads (which have two similar nuclei per cell), and the monokaryotic enteromonads, retortamonads and Carpediemonas, with the more typical one nucleus per cell. The monophyly of the group was confirmed by molecular phylogenetic studies, but neither the internal phylogeny nor its position on the eukaryotic tree has been clearly resolved.     

Predictions of Taylor's power law, density dependence and pink noise from a neutrally modeled time series

There has recently been increasing interest in neutral models of biodiversity and their ability to reproduce the patterns observed in nature, such as species abundance distributions. Here we investigate the ability of a neutral model to predict phenomena observed in single-population time series, a study complementary to most existing work that concentrates on snapshots in time of the whole community. We consider tests for density dependence, the dominant frequencies of population fluctuation (spectral density) and a relationship between the mean and variance of a fluctuating population (Taylor's power law). We simulated an archipelago model of a set of interconnected local communities with variable mortality rate, migration rate, speciation rate, size of local community and number of local communities. Our spectral analysis showed ‘pink noise’: a departure from a standard random walk dynamics in favor of the higher frequency fluctuations which is partly consistent with empirical data. We detected density dependence in local community time series but not in metacommunity time series. The slope of the Taylor's power law in the model was similar to the slopes observed in natural populations, but the fit to the power law was worse. Our observations of pink noise and density dependence can be attributed to the presence of an upper limit to community sizes and to the effect of migration which distorts temporal autocorrelation in local time series. We conclude that some of the phenomena observed in natural time series can emerge from neutral processes, as a result of random zero-sum birth, death and migration. This suggests the neutral model would be a parsimonious null model for future studies of time series data.