Intracellular Leishmania: your iron or mine?

Iron is a co-factor for several essential enzymes and biochemical pathways, including those required for replication of pathogens such as Leishmania in macrophages. Iron acquisition is emerging as a key battleground in which the iron import systems of microbes are pitted against the iron withdrawal and sequestration systems of macrophages, with both competing for iron at the interface of host-pathogen interaction. The recent characterization of a ferrous iron transport system (LIT1) in Leishmania amazonensis that is induced intracellularly and is required for survival in macrophages and for virulence in vivo provides an elegant example of the adaptation of protozoa to the iron-poor phagosomal environment.     

'Proteomineering': has the mine been excavated?

Evaluation of: Di Girolamo F, Boschetti E, Chung MC, Guadagni F, Righetti PG. 'Proteomineering' or not? The debate on biomarker discovery in sera continues. J. Proteomics 74(5), 589-594 (2011). The combinatorial peptide ligand library in association with mass spectrometry can greatly enhance the dynamic range of the analysis of low- and very low-abundance proteins constituting the vast majority of species in any sample. When compared with untreated samples, the increment in detection of low-abundance species appears to be at least fourfold. Recently, the combinatorial peptide ligand library has been challenged; however, it has been clearly demonstrated in the evaluated paper that the protocols for elution of the captured polypeptides make the difference. Therefore, the solid-phase ligand library made of hexapeptides remains a promising and unique tool for biomarker discovery.     

Microbial oxidation of arsenite and occurrence of arsenite‐oxidizing bacteria in acid mine water from a sulfur‐pyrite mine

The acid mine waters (pH 2.0–2.4) discharged from the Matsuo sul‐fur‐pyrite mine contained high concentrations of dissolved inorganic arsenic (2–13 ppm). Arsenic in the superficial acid mine waters was predominantly in the (V) state (arsenate); however, the element in the water from a deep mine drift was almost in the (III) state (arsenite). Microbial arsenite oxidation occurred in the acid mine waters and along the stream of the river, which was contaminated with a large volume of the mine drift water. Arsenite (500 ppm As)‐resistant bacteria (0–27 colonies/ml) were detected in the water samples and 208 slant cultures were obtained. Arsenite‐oxidizing activities of all the cultures were determined and six strains with strong arsenite‐oxidizing activity were isolated. These bacteria were acidophilic (optimum growth pH, 3—4), gram‐negative, aerobic, and rod‐shaped. They could not oxidize ferrous iron and elemental sulfur as a sole energy source and not derive the energy for chemoautotrophic growth from arsenite oxidation.     

A meta-taxonomic investigation of the prokaryotic diversity of water bodies impacted by acid mine drainage from the São Domingos mine in southern Portugal

Extremophiles - The prokaryotic communities of water bodies contaminated by acid mine drainage from the São Domingos mining area in southern Portugal were analyzed using a meta-taxonomics...     

Microbial leaching of arsenic from low‐sulfide gold mine material

Drainages from high‐sulfide tailings near abandoned lode deposits in Alaska, U.S.A., and Yukon, Canada, were found to be acidic, to contain large numbers of Thiobacillus ferrooxidans, and to have high concentrations of dissolved arsenic. Drainages from active placer gold mines are not acidic, but T. ferrooxidans and concentrations of dissolved arsenic exceeding 10 μg/L are found in some streams affected by placer mine drainage. Placer mine material containing low amounts of sulfides (326 (μg/g) and moderately high amounts of arsenic (700 μg/g) was leached with growing cultures of T. ferrooxidans, T. ferrooxidans‐spent filtrate, and acid ferric sulfate. The results showed that while more arsenic was released from this material by growing cultures of T. ferrooxidans than by abiotic controls, acid ferric sulfate released much more arsenic than did either growing cultures of T. ferrooxidans or spent culture filtrate containing oxidized iron. Cation exchange chromatography showed that oxidized iron from T. ferrooxidans culture filtrate is chemically less reactive than the iron in aqueous solutions of ferric sulfate salt. These results indicate that arsenic release from both high‐ and low‐sulfide mine wastes is enhanced biologically, but that rates and amounts of arsenic release are primarily controlled by iron species.     

Is rhizosphere remediation sufficient for sustainable revegetation of mine tailings?

Background

Revegetation of mine tailings (fine-grained waste material) starts with the reconstruction of root zones, consisting of a rhizosphere horizon (mostly topsoil and/or amended tailings) and the support horizon beneath (i.e. equivalent to subsoil – mostly tailings), which must be physically and hydro-geochemically stable. This review aims to discuss key processes involved in the development of functional root zones within the context of direct revegetation of tailings and introduces a conceptual process of rehabilitating structure and function in the root zones based on a state transition model.

Scope

Field studies on the revegetation of tailings (from processing base metal ore and bauxite residues) are reviewed. Particular focus is given to tailings'' properties that limit remediation effectiveness. Aspects of root zone reconstruction and vegetation responses are also discussed.

Conclusions

When reconstructing a root zone system, it is critical to restore physical structure and hydraulic functions across the whole root zone system. Only effective and holistically restored systems can control hydro-geochemical mobility of acutely and chronically toxic factors from the underlying horizon and maintain hydro-geochemical stability in the rhizosphere. Thereafter, soil biological capacity and ecological linkages (i.e. carbon and nutrient cycling) may be rehabilitated to integrate the root zones with revegetated plant communities into sustainable plant ecosystems. A conceptual framework of system transitions between the critical states of root zone development has been proposed. This will illustrate the rehabilitation process in root zone reconstruction and development for direct revegetation with sustainable plant communities. Sustainable phytostabilization of tailings requires the systematic consideration of hydro-geochemical interactions between the rhizosphere and the underlying supporting horizon. It further requires effective remediation strategies to develop hydro-geochemically stable and biologically functional root zones, which can facilitate the recovery of the microbial community and ecological linkages with revegetated plant communities.     

What processes shape early-successional vegetation in fly ash and mine tailings?

Local abiotic filters and regional processes (i.e., regional pools of species that are dispersal-limited to varying degrees) interactively structure the development of vegetation in human-disturbed habitats, yet their relative contributions to this process are still to be determined. In this study conducted in the Czech Republic, we related plant species diversity and composition of 10 fly ash and 7 mine tailings to local edaphic conditions, and to vegetation from a 100-m perimeter (regional species pool). We found that the species richness and composition on the tailings were significantly associated with diversity and composition of vegetation in the surroundings, but not with the local edaphic conditions. Species from adjacent vegetation that were more abundant and those producing lighter seeds were more likely to establish on the tailings. The same characteristics also enhanced species abundance on the tailings, but the two predictors explained less than 10% in variation of establishment success or of species abundance. A non-significant relationship between species number and tailings size, but a significant association between diversity and time of vegetation development indicate that the study systems are still far from equilibrium. Our study provides evidence for a strong effect of regional processes, with a limited influence of measured edaphic conditions on plant communities developing de novo. It also highlights the necessity to consider the broader spatial context in the analysis of vegetation succession in human-disturbed habitats.     

Generation of acid mine drainage around the Karaerik copper mine (Espiye,Giresun, NE Turkey): implications from the bacterial population in the Acısu effluent

The Karaerik Cu mine is a worked-out deposit with large volumes of tailings and slags which were left around the mine site without any protection. Natural feeding of these material and run-off water from the mineralised zones into the Ac?su effluent causes a serious environmental degradation and creation of acid mine drainage (AMD) along its entire length. This research aims at modelling the formation of AMD with a specific attempt on the characterisation of the bacterial population in association with AMD and their role on its occurrence. Based on 16SrRNA analyses of the clones obtained from a composite water sample, the bacterial community was determined to consist of Acidithiobacillus ferrivorans, Ferrovum myxofaciens, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans as iron-oxidising bacteria, Acidocella facilis, Acidocella aluminiidurans, Acidiphilium cryptum and Acidiphilium multivorum as iron-reducing bacteria, and Acidithiobacillus ferrivorans, Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Acidiphilium cryptum as sulphur-oxidising bacteria. This association of bacteria with varying roles was interpreted as evidence of a concomitant occurrence of sulphur and iron cycles during the generation of AMD along the Ac?su effluent draining the Karaerik mine.     

Microalgae–bacteria biofilms: a sustainable synergistic approach in remediation of acid mine drainage

Applied Microbiology and Biotechnology - Microalgae and bacteria offer a huge potential in delving interest to study and explore various mechanisms under extreme environments. Acid mine drainage...     

Conversation between apoptosis and autophagy: “Is it your turn or mine?”

Drug resistance of cancer cells is often correlated with apoptosis evasion; however, an active involvement of autophagy in this scenario has been recently proposed, based on the evidence that autophagy could exert a protective role toward the activation of apoptosis in cancer cells. In this review, we briefly review the basic features of apoptosis, and we describe in details the molecular patterns of autophagy, with a special emphasis on its still controversial physiological function(s). The crucial factors governing the cross talk between autophagy and apoptosis will be illustrated.     

Riparian plants on mine runoff in Zimapan,Hidalgo, Mexico: Useful for phytoremediation?

Dispersion and runoff of mine tailings have serious implications for human and ecosystem health in the surroundings of mines. Water, soils and plants were sampled in transects perpendicular to the Santiago stream in Zimapan, Hidalgo, which receives runoff sediments from two acidic and one alkaline mine tailing. Concentrations of potentially toxic elements (PTE) were measured in water, soils (rhizosphere and non-rhizosphere) and plants. Using diethylenetriaminepentaacetic acid (DTPA) extractable concentrations of Cu, Zn, Ni, Cd and Pb in rhizosphere soil, the bioconcentration and translocation factors were calculated. Ruderal annuals formed the principal element of the herbaceous vegetation. Accumulation was the most frequent strategy to deal with high concentrations of Zn, Cu, Ni, Cd and Pb. The order of concentration in plant tissue was Zn>Pb>Cu>Ni>Cd. Most plants contained concentrations of PTE considered as phytotoxic and behaved as metal tolerant species. Rorippa nasturtium-aquaticum accumulated particularly high concentrations of Cu. Parietaria pensylvanica and Commelina diffusa, common tropical weeds, behaved as Zn hyperaccumulators and should be studied further.     

Your place or mine? A phylogenetic comparative analysis of marital residence in Indo-European and Austronesian societies

Accurate reconstruction of prehistoric social organization is important if we are to put together satisfactory multidisciplinary scenarios about, for example, the dispersal of human groups. Such considerations apply in the case of Indo-European and Austronesian, two large-scale language families that are thought to represent Neolithic expansions. Ancestral kinship patterns have mostly been inferred through reconstruction of kin terminologies in ancestral proto-languages using the linguistic comparative method, and through geographical or distributional arguments based on the comparative patterns of kin terms and ethnographic kinship 'facts'. While these approaches are detailed and valuable, the processes through which conclusions have been drawn from the data fail to provide explicit criteria for systematic testing of alternative hypotheses. Here, we use language trees derived using phylogenetic tree-building techniques on Indo-European and Austronesian vocabulary data. With these trees, ethnographic data and Bayesian phylogenetic comparative methods, we statistically reconstruct past marital residence and infer rates of cultural change between different residence forms, showing Proto-Indo-European to be virilocal and Proto-Malayo-Polynesian uxorilocal. The instability of uxorilocality and the rare loss of virilocality once gained emerge as common features of both families.     

Sphingomonas gimensis sp. nov., a novel Gram-negative bacterium isolated from abandoned lead–zinc ore mine

A novel bacterial strain designated 9PNM-6^T was isolated from an abandoned lead–zinc ore mine site in Meizhou, Guangdong Province, China. The isolate was found to be Gram-negative, rod-shaped, orange-pigmented, strictly aerobic, oxidase- and catalase-positive. Growth occurred at 0–4 % NaCl (w/v, optimum, 0 %), at pH 6.0–8.0 (optimum, pH 7.0) and at 15–32 °C (optimum, 28–30 °C). Phylogenetic analysis based on 16S rRNA gene sequence similarities showed that strain 9PNM-6^T belongs to the genus Sphingomonas, with the highest sequence similarities with Sphingomonas jejuensis NBRC 107775^T (99.7 %), Sphingomonas koreensis KCTC 2882^T (95.1 %) and Sphingomonas dokdonesis KCTC 12541^T (95.1 %). The chemotaxonomic characteristics of strain 9PNM-6^T were consistent with those of the genus Sphingomonas. The predominant respiratory quinone was identified as ubiquinone Q-10, the major polyamine as sym-homospermidine, and the major cellular fatty acids as C_18:1 ω7c, C_16:0, C_16:1 ω7c and/or C_16:1 ω6c and C_14:0 2-OH. The major polar lipids are sphingoglycolipid, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatideylcholine, an unidentified phospholipid and four unidentified aminolipids. The genomic DNA G+C content of strain 9PNM-6^T was determined to be 69.2 ± 0.6 mol%. Based on comparative analyses of morphological, physiological and chemotaxonomic data, and levels of DNA–DNA relatedness values, strain 9PNM-6^T is considered to represent a novel species of the genus Sphingomonas, for which the name Sphingomonas gimensis sp. nov. (Type strain 9PNM-6^T = GIMCC 1.655^T = CGMCC 1.12671^T = DSM 27569^T) is proposed.     

Algal diversity in flowing waters at an acidic mine drainage “barrens” in central Pennsylvania,USA

Microscopic investigations were undertaken to decipher the diversity in the lotic algal communities from acidic waters (pH 2.4–3.2) flowing overland in sheets and channels at an acid mine drainage (AMD) barrens near Kylertown, PA, USA. Microscopic observations, supplemented with taxonomic keys, aided in identification of the dominant algae, and measurement of carbon from adjacent soils was undertaken. The unicellular protist Euglena sp. was most abundant in slower flowing waters (i.e., pool near point of emergence and surficial flow sheets), while Ulothrix sp. was most abundant in faster flowing water from the central stream channel. A diverse range of unicellular microalgae such as Chlorella, Cylindrocystis, Botryococcus, and Navicula and several filamentous forms identified as Microspora, Cladophora, and Binuclearia were also recorded. The observed high algal diversity may be related to the long duration of AMD flow at this site which has led to the development of adapted algal communities. The comparatively higher carbon content in soil materials adjacent to slower flowing water sampling locations provides evidence for the important role of algae as primary producers in this extreme environment.     

Vegetation pattern and heavy metal accumulation at a mine tailing at Gyöngyösoroszi, hungary

Vegetation at an abandoned heavy metal bearing mine tailing may have multifunctional roles such as modification of water balance, erosion control and landscape rehabilitation. Research on the vegetation of mine tailings can provide useful information on tolerance, accumulation and translocation properties of species potentially applicable at moderately contaminated sites. Analyses of the relationship between heavy metal content (Pb, Zn and Cu) and vegetation in a mine tailing were carried out. These analyses included: (1) spatial analysis of relationship among heavy metal distribution, pH and vegetation patterns, and (2) analysis of heavy metal accumulation and translocation in some plant species. Presence of vegetation was found to be significantly dependent on pH value, which confirms that phytotoxicity is a function of element concentration in solution, which is primarily controlled by pH value in mine tailings. Among the most abundant plant species, dewberry (Rubus caesius), vipersbugloss (Echium vulgare), scarlet pimpernel (Anagallis arvensis) and narrowleaf plantain (Plantago lanceolata) accumulate significant amounts of Pb, Cu and Zn, while in the case of annual bluegrass (Poa annua) only Pb can be measured in elevated contents. Considering the translocation features, scarlet pimpernel, narrowleaf plantain, and dewberry accumulate heavy metals primarily in their roots, while heavy metal concentration in vipersbugloss and annual bluegrass is higher in the shoots.