STRUCTURE AND FUNCTION OF BENTHIC ALGAL COMMUNITIES IN AN EXTREMELY ACID RIVER1

The composition of algal species and pigments and the structural and functional characteristics of the algal community were investigated in an acid stream of southwestern Spain, the Río Tinto. The algal community had low diversity and showed few seasonal differences. It was mainly made up of Klebsormidium flaccidum Kütz. (Silva, Mattox & Blackwell) that produced long greenish or purplish filaments, Pinnularia acoricola Hust. (producing brown patches) and Euglena mutabilis Schmitz. The algal filaments made up a consistent biofilm that also included fungal hyphae, iron bacterial sheaths, diatoms, and mineral particles. HPLC analyses on Río Tinto samples showed that undegraded chl accounted for 67% of the total chl in the filamentous patches but were a minority in the brown patch (2.6%). The brown patch had a concentration of carotenoids eight times lower than that observed in the green patch. When chl concentrations were weighted for the proportion of the different patches on the streambed, undegraded chl a accounted for 89.2 mg chl a·m ^{? 2} of stream surface area (5.4 g C·m ^{? 2}). This high algal biomass was supported by relatively high nutrient concentrations and by a high phosphatase activity (V_max = 137.7 nmol methylumbelliferyl substrate·cm ^{? 2}·h ^{? 1} 1 Received 15 July 2002. Accepted 17 February 2003. , K_m = 0.0045 μM). The remarkable algal biomass in Río Tinto potentially contributed to the bacterial–fungal community and to the macroinvertebrate community and emphasizes the role that the algae may have in the organic matter cycling and energy flow in extreme systems dominated by heterotrophic microorganisms.     

Cetopsis varii,a new species of whale catfish (Siluriformes: Cetopsidae) from the Meta Basin,Colombia

Cetopsis varii sp. nov. Cetopsidae (Cetopsinae) is described from the Río Meta basin in eastern Colombia, at middle portions of the Río Orinoco basin. The new species differs from congeners by a combination of features: the absence of a humeral spot, presence of eye, conical teeth on vomer and dentary and rounded posterior nares, along with details of body, dorsal and caudal‐fin pigmentation. The osteology of the new species is investigated through high‐resolution X‐ray computed tomography and cleared and stained specimens. Data thus obtained are used to code the new species for character states utilized in a previous phylogenetic analysis of Cetopsidae. Analysis of the expanded matrix shows that C. varii is the sister group to C. orinoco.     

Geographic distribution and demography of Pithecia aequatorialis (pitheciidae) in Peruvian Amazonia

To study the geographic distribution and demographic characteristics of Pithecia aequatorialis in Peruvian Amazonia, we undertook surveys and transect census in three river basins (Río Itaya, Río Tigre and Río Curaray) between 2004 and 2008. A total of 123 groups of P. aequatorialis was encountered during 1623 km of transect walks. Group size was uniform among the three areas (3.4–3.6 individuals), but surprisingly, population densities were higher in the area with strong hunting pressure (Río Itaya: 7.8 ind./km², vs. 5.6 and 5.9 km² in the Río Tigre and Río Curaray basins, respectively). The most common group composition included an adult pair with one offspring. Groups with more than one adult male and/or female accounted for 35% of sightings. Our observations extend P. aequatorialis range in Peru further south to the area between the Río Tigre and Río Corrientes, but exclude the area to the north between the Río Curaray and Río Napo. These findings are in contrast to previous distribution maps. P. aequatorialis was rarely seen in interspecific association during our censuses. Am. J. Primatol. 71:964–968, 2009. © 2009 Wiley‐Liss, Inc.     

XANES Investigation of Dynamic Phase Transition in Olivine Cathode for Li‐Ion Batteries

Dynamic phase transformation in olivine LiFePO₄ involving formation of one or more intermediate or metastable phases is revealed by an in situ time‐resolved X‐ray absorption near edge structure (XANES) technique. The XANES spectra measured during relaxation immediately after the application of relatively high overpotentials, where metastable phases are expected, show a continuous shift of the Fe K‐edge toward higher energy. Surprisingly, the Fe K‐edge relaxes to higher energies after current interrupt regardless of whether the cell is being charged or discharged. This relaxation phenomenon is superimposed upon larger shifts in K‐edge due to changes in Fe^2+/Fe³⁺ ratio due to charging and discharging, and implies an intermediate phase of larger Fe? O bond length than any of the known crystalline phases. No intermediate crystalline phases are observed by X‐ray diffraction (XRD). A metastable amorphous phase formed during dynamic cycling and which structurally relaxes to the equilibrium crystalline phases over a time scale of about 10 min after cessation of charging/discharging current is consistent with the experimental observations.     

Metal Uptake and Distribution in Cultured Seedlings of Nerium oleander L. (Apocynaceae) from the Río Tinto (Huelva, Spain)

Nerium oleander L. (Apocynaceae) is a micro-nano phanerophyte that grows in the riverbanks of the Río Tinto basin (Southwest Iberian Peninsula). The waters and soils of the Río Tinto area are highly acidic and have high concentrations of heavy metals. In this environment, N. oleander naturally grows in both extreme acidic (EA) and less extreme acidic (LEA) water courses, excluding, and bioindicating certain metals. In this work, we compared and evaluated the accumulation preferences and capacities, the distribution and processes of biomineralization of metals (Fe, Cu, Zn, Mn, Mg, Ca) in the first stages of growth of EA and LEA oleanders by means of inductively coupled plasma–mass spectrometry, scanning electron microscopy, and energy dispersive X-ray analyzer analysis. Seeds from both environments were grown and treated with a self-made solution simulating the most extreme red waters from the Río Tinto. LEA plants drastically reduces the metal uptake at the beginning, but later reactivates the uptake reaching concentration values in the same range as the EA plants. The results showed high Mn, Zn and Mg concentrations, accumulation of Fe and Cu in plants from both environments, differing from the metal concentrations of field-grown oleanders. Iron bioformations with traces of other metals were present inside and over epidermal cells and inside vascular cells of stems and roots. They were absent of leaves. The accumulation properties of N. oleander in its early stages of development make it a species to take in consideration in phytoremediation processes but optimized conditions are needed to ensure enough biomass production.     

Metal Accumulation Screening of the Río Tinto Flora (Huelva,Spain)

Río Tinto (Huelva, Spain) is located in one of the most important mining regions in the world. Its soils are characterized by their extreme acidity and elevated concentrations of heavy metals. Due to these characteristics, the Tinto ecosystem is considered unique and an ideal location to study biological adaptations to this type of habitat. Plant species that present these adaptations might be useful to mining and other metal pollution restoration programs. This study reports the results for the screening of Ca, Mg, Na, Mn, Fe, Ni, Cu, Zn, As, and Pb in aerial tissues of 97 plant species from the Tinto basin flora. In addition, plant–soil relationships were analyzed using the biological absorption coefficient (BAC) to detect the main plant adaptations in the Tinto flora. The species selected are representative of the biomass of the main dominant edaphophile and climatophile vegetation communities of the three river sections, forest, and subseral stages. Plant and soil elemental analyses were performed using inductively coupled plasma–mass spectrometry technique (ICP-MS). The results indicate that in general, Tinto flora shows a pattern of accumulation of the analyzed elements in aerial tissues which agrees with the nutritional requirements of vascular plants (macronutrients > micronutrients > indifferent or toxic elements). Among macronutrients, Ca seems to be an essential element in this habitat. This element accumulates in the aerial plant tissues. Basically, the Río Tinto flora is made of Fe, Cu, Zn, Ni, As, and Pb excluders, although some analyzed species of Erica, Quercus, Lavandula, Cistus, Genista, and Cytisus genera can be considered Mn accumulators. The results of this study make up a body of fundamental knowledge of the strategies used by plants to thrive in habitats with high concentrations of toxic heavy metals. This information is vital when it comes to planning a restoration program. Plants must be selected and used according to the requirements, always respecting the characteristics of the territory and facilitating the development of suitable vegetation.     

Environmental modulation of reproductive activity of the invasive mussel Limnoperna fortunei: implications for antifouling strategies

Limnoperna fortunei (Dunker, 1857) (Bivalvia) invaded Argentina through the Río de la Plata estuary around 1990 and is presently established throughout five South American countries as a dominant component of the benthic fauna and a major nuisance for industry and power plants. Between 1997 and 2006 we monitored the reproductive activity of L. fortunei through weekly measurements of planktonic larvae in six South American water bodies: Río de la Plata estuary, Paraná and Carapachay rivers, Salto Grande, Itaipú and Embalse de Río Tercero reservoirs. Mean larval densities varied between 4000 and 7000 individuals m^?3; except in the reservoirs of Itaipú (450 ind. m^?3) and Salto Grande (869 ind. m^?3), where the mussel was first recorded shortly before our surveys, and upstream dispersal is limited (Salto Grande). In all cases, reproductive output decreases during the winter. At four of the six sites surveyed larval densities were comparatively high for 8.8–10.2 months per year. A lower food supply is possibly responsible for the shorter reproductive period of 5.9 months at Embalse. At Salto Grande, there is a well‐defined mid‐summer drop in larval numbers, coinciding with blooms of cyanobacteria. We propose that, in addition to temperature, two major factors may regulate the reproductive activity of L. fortunei: (i) the availability of food; and (ii) blooms of toxic cyanobacteria, significantly shortening the otherwise very long reproductive period. This information is important for the design of antifouling programmes involving the use of molluscicides, and has potential for reduced biocide use. These results provide supporting evidence for some fundamental ecological theories of invasions discussed here.     

Proteomic analysis of the response of an acidophilic strain of Chlamydomonas sp. (Chlorophyta) to natural metal‐rich water

A proteomic approach including 2‐DE and MALDI‐TOF analysis has been developed to identify the soluble proteins of the unicellular photosynthetic algae Chlamydomonas sp. isolated from an extreme acidic environment, Río Tinto (southwest Spain). We have analyzed the soluble proteome obtained from whole cells growing on metal‐rich natural acidic water from the river in comparison with the same strain growing in artificial BG‐11 media. The most drastic effect was the decrease in the abundance of the ribulose‐1,5‐biphosphate carboxylase as well as other enzymes related to photosynthesis. However, phytochrome B, phosphoribulokinase, and phosphoglycerate kinase were upregulated when cells were grown in metal‐rich acidic water. Besides, increased accumulation of two Hsps, Hsp70 and Hsp90 as well as other stress‐related enzymes were also found in the cells growing in natural acidic water. These results suggest that naturally occurring metal‐rich water induces a stress response in acidophilic Chlamydomonas forcing algal cells to reorganize their metabolic pathways as an adaptive response to these environmental conditions.     

Characterization of biogenic iron oxides collected by the newly designed liquid culture method using diffusion chambers

We designed a new culture method for neutrophilic iron‐oxidizing bacteria using liquid medium (i) to study the formation and mineralogical characteristics of biogenic iron oxides (BIOS) and (ii) to apply BIOS to various scientific and engineering applications. An iron‐oxidizing bacterium, Mariprofundus ferrooxydans PV‐1^T (ATCC, BAA–1020), was cultured using a set of diffusion chambers to prepare a broad anoxic–oxic interface, upon which BIOS formation is typically observed in natural environments. Iron oxide precipitates were generated in parallel with bacterial growth. A scanning electron microscopy analysis indicated that the morphological features of the iron oxide precipitates in the medium (in vitro BIOS) were similar to those of BIOS collected from natural deep‐sea hydrothermal environments in the Northwest Eifuku Seamount field in the northern Mariana Arc (in situ BIOS). Further chemical speciation of both the in vitro and in situ BIOS was examined with X‐ray absorption fine structure (XAFS). A bulk XAFS analysis showed that the minerals in both BIOS were mainly ferrihydrite and oligomeric stages of amorphous iron oxyhydroxides with edge‐sharing octahedral linkages. The amount of in vitro BIOS produced with the diffusion‐chamber method was greater than those produced previously with other culture methods, such as gel‐stabilized gradient and batch liquid culture methods. The larger yields of BIOS produced with the new culture method will allow us to clarify in the future the mineralization mechanisms during bacterial growth and to examine the physicochemical properties of BIOS, such as their adsorption to and coprecipitation with various elements and substances.     

Facile Metal Coordination of Active Site Imprinted Nitrogen Doped Carbons for the Conservative Preparation of Non‐Noble Metal Oxygen Reduction Electrocatalysts

Iron‐ or cobalt‐coordinated heteroatom doped carbons are promising alternatives for Pt‐based cathode catalysts in polymer‐electrolyte fuel cells. Currently, these catalysts are obtained at high temperatures. The reaction conditions complicate the selective and concentrated formation of metal–nitrogen active sites. Herein a mild procedure is introduced, which is conservative toward the carbon support and leads to active‐site formation at low temperatures in a wet‐chemical metal‐coordination step. Active‐site imprinted nitrogen doped carbons are synthesized via ionothermal carbonization employing Lewis‐acidic Mg²⁺ salt. The obtained carbons with large tubular porosity and imprinted N₄ sites lead to very active catalysts with a half‐wave potential (E_1/2) of up to 0.76 V versus RHE in acidic electrolyte after coordination with iron. The catalyst shows 4e^? selectivity and exceptional stability with a half‐wave potential shift of only 5 mV after 1000 cycles. The X‐ray absorption fine structure as well as the X‐ray absorption near edge structure profiles of the most active catalyst closely match that of iron(II)phthalocyanine, proving the formation of active and stable FeN₄ sites at 80 °C. Metal‐coordination with other transition metals reveals that Zn–N_x sites are inactive, while cobalt gives rise to a strong performance increase even at very low concentrations.     

Magnetite as a precursor for green rust through the hydrogenotrophic activity of the iron‐reducing bacteria Shewanella putrefaciens

Magnetite (Fe^IIFe^III₂O₄) is often considered as a stable end product of the bioreduction of Fe^III minerals (e.g., ferrihydrite, lepidocrocite, hematite) or of the biological oxidation of Fe^II compounds (e.g., siderite), with green rust (GR) as a mixed Fe^II‐Fe^III hydroxide intermediate. Until now, the biotic transformation of magnetite to GR has not been evidenced. In this study, we investigated the capability of an iron‐reducing bacterium, Shewanella putrefaciens, to reduce magnetite at circumneutral pH in the presence of dihydrogen as sole inorganic electron donor. During incubation, GR and/or siderite (Fe^IICO₃) formation occurred as secondary iron minerals, resulting from the precipitation of Fe^II species produced via the bacterial reduction of Fe^III species present in magnetite. Taking into account the exact nature of the secondary iron minerals and the electron donor source is necessary to understand the exergonic character of the biotic transformation of magnetite to GR, which had been considered to date as thermodynamically unfavorable at circumneutral pH. This finding reinforces the hypothesis that GR would be the cornerstone of the microbial transformations of iron‐bearing minerals in the anoxic biogeochemical cycle of iron and opens up new possibilities for the interpretation of the evolution of Earth's history and for the understanding of biocorrosion processes in the field of applied science.     

Numbers of iron‐oxidizing bacteria and oxidation potential of sulfur and iron components in coal refuse amended with limestone and sewage sludge

Counts of acidophilic iron‐oxidizing bacteria, ratios of S₂O₃=—S/SO₄=—S and Fe⁺³/Fe⁺², and S₂O₃=—S oxidation potentials were examined over a two‐year period in coal refuse (acid gob) treated with limestone and/or sewage sludge. A non‐amended treatment was used as a control.

No significant difference in population counts of acidophilic iron‐oxidizing bacteria were observed between treatments in either year of the study. S₂O₃=—S/SO₄=—S and Fe⁺³/Fe⁺² ratios indicated active sulfur and iron oxidation suggesting that limestone and/or sewage sludge may be ineffective in suppressing pyrite oxidation. Under optimal conditions, S₂O₃=—S oxidation potentials (in vitro) showed a logarithmic increase in SO₄=—S formation for all four treatments over time. The final pH of the treatments following twenty days of perfusion ranged from 3.06 to 3.59.     

Effects of added organic matter on iron and manganese redox systems in sediment

Addition of five types of organic matter to Lake Washington sediments resulted in release of high concentrations of iron, organic carbon, and manganese into the interstitial water, and caused an increase in observed sediment oxygen consumption rates. The depressed electrode potentials (E_h < —150 mV) that should accompany such reduction processes did not occur, indicating that E_h was being poised by redox systems present in the sediment. Iron redox systems [Fe(OH)₃‐Fe²⁺, Fe₃(OH)₈‐Fe²⁺, and Fe(OH)₃‐Fe₃(OH)₈] were shown to be poising the E_h of control sediments throughout 13 weeks of incubation and dominating the potential of several of the organically amended sediments following the first three weeks of incubation. Depression of calculated iron system E_o values relative to that of the control sediment early in the incubation appeared to be due to the decreased pH and non‐equilibrium conditions in the organic matter‐amended sediment during the first weeks of incubation. Manganese redox systems exerted no discernable impact on the E_h of the sediment.     

A new species of Profundulus (Cyprinodontiformes: Profundulidae) from the Honduran central highlands

A new species of Profundulus, Profundulus portillorum, from the Honduran central highlands is described. Profundulus portillorum belongs to the Profundulus labialis species group and is distinct from the Profundulus punctatus species group in that it lacks a humeral spot and less than half of the caudal fin is scaled. Within the P. labialis species group, P. portillorum has a more slender body, smaller eye, fewer anal rays, caudal rays and lateral‐line scales than other species. Forty‐one specimens were collected around emergent vegetation in the margins of two small (2–5 m in width, 20–40 cm in depth), high‐elevation (1300 m) tributaries of the Río Calam within the Río Ulúa drainage. These specimens represent the easternmost collection of any Profundulus and the first collection of any member of the P. labialis species group from Honduras.     

Rational Design of Hierarchically Open‐Porous Spherical Hybrid Architectures for Lithium‐Ion Batteries

Controlling the internal microstructure and overall morphology of building blocks used to form hybrid materials is crucial for the realization of deterministically designed architectures with desirable properties. Here, integrative spray‐frozen (SF) assembly is demonstrated for forming hierarchically structured open‐porous microspheres (hpMSs) composed of Fe₃O₄ and reduced graphene oxide (rGO). The SF process drives the formation of a radially aligned microstructure within the sprayed colloidal droplets and also controls the overall microsphere morphology. The spherical Fe₃O₄/rGO hpMSs contain interconnected open pores, which, when used as a lithium‐ion battery anode, enables them to provide gravimetric and volumetric capacities of 1069.7 mAh g^?1 and 686.7 mAh cm^?3, much greater than those of samples with similar composition and different morphologies. The hpMSs have good rate and cycling performance, retaining 78.5% capacity from 100 to 1000 mA g^?1 and 74.6% capacity over 300 cycles. Using in situ synchrotron X‐ray absorption spectroscopy, the reaction pathway and phase evolution of the hpMSs are monitored enabling observation of the very small domain size and highly disordered nature of Fe_xO_y. The reduced capacity fade relative to other conversion systems is due to the good electrical contact between the pulverized Fe_xO_y particles and rGO, the overall structural integrity of the hpMSs, and the interconnected open porosity.     

X‐ray fluorescence analysis of iron and manganese distribution in primary dopaminergic neurons

Transition metals have been suggested to play a pivotal role in the pathogenesis of Parkinson's disease. X‐ray microscopy combined with a cryogenic setup is a powerful method for elemental imaging in low concentrations and high resolution in intact cells, eliminating the need for fixation and sectioning of the specimen. Here, we performed an elemental distribution analysis in cultured primary midbrain neurons with a step size in the order of 300 nm and ~ 0.1 ppm sensitivity under cryo conditions by using X‐ray fluorescence microscopy. We report the elemental mappings on the subcellular level in primary mouse dopaminergic (DAergic) and non‐DAergic neurons after treatment with transition metals. Application of Fe²⁺ resulted in largely extracellular accumulation of iron without preference for the neuronal transmitter subtype. A quantification of different Fe oxidation states was performed using X‐ray absorption near edge structure analysis. After treatment with Mn²⁺, a cytoplasmic/paranuclear localization of Mn was observed preferentially in DAergic neurons, while no prominent signal was detectable after Mn³⁺ treatment. Immunocytochemical analysis correlated the preferential Mn uptake to increased expression of voltage‐gated calcium channels in DAergic neurons. We discuss the implications of this differential elemental distribution for the selective vulnerability of DAergic neurons and Parkinson's disease pathogenesis.     

Microbial population structure in a stratified,acidic pit lake in the Iberian Pyrite Belt

Abstract

We examined the geochemistry and bacterial and archaeal community structure in the acidic (pH < 2.4) pit lake at Peña de Hierro, near the headwaters of the Río Tinto. The lake has strong vertical gradients in light, O₂, pH, conductivity, and dissolved ions. Bacterial and archaeal communities between 0 and 32?m displayed low species richness and evenness. Relatives of iron cycling taxa accounted for 60-90% of the operational taxonomic units (OTUs) throughout the water column. Relatives of heterotrophic, facultative Fe(III)-reducing species made up more than a third of the bacterial and archaeal community in the photic zone. Taxa related to Fe(II) oxidizers Ferrithrix thermotolerans and Acidithix ferrooxidans were also abundant in the photic zone. Below the photic zone, relatives of the lithoautotrophic Fe(II) oxidizers Leptospirillum ferrooxidans and Ferrovum myxofaciens bloomed at different depths within or just below the oxycline. Thermoplasmatales predominated in the deep, microoxic zone of the lake. The microbial population structure of the lake appears to be influenced by the production of oxygen and organic matter by phototrophs in a narrow zone at the lake surface and by strong geochemical gradients present in the water column that create distinct niches for separate Fe(II) oxidizers.     

Population densities and geographic distribution of night monkeys (Aotus nancymai and Aotus vociferans) (cebidae: Primates) in Northeastern Peru

Population densities of two species of night (or owl) monkeys (Aotus nancymai and Aotus vociferans) were estimated using transect census methods. Densities of Aotus nancymai were approximately 46.3 individuals/km² in lowland forests and 24.2 individuals/km² in highland forests. For Aotus vociferans densities were 33.0 individuals/km² in lowland forests and 7.9 individuals/km² in highland forests. A. vociferans occurs north of the Río Amazonas-Marañon and A. nancymai south of it, except for the northern enclave between the Ríos Tigre and Pastaza. The two species are nowhere sympatric. However, the two known karyotypic forms of A. vociferans occupy the same habitats throughout the Peruvian range of the species.     

Iron plaque enhances phosphorus uptake by rice (Oryza sativa) growing under varying phosphorus and iron concentrations

Both solution culture and pot experiments were performed to investigate (a) the effects of external Fe (II) concentrations and forms on the formation of iron plaque on the roots of rice (Oryza sativa) and subsequent P adsorption on iron plaque and shoot P concentrations and (b) the effects of soil moisture regimes on the formation of iron plaque and P adsorption on root surfaces and P accumulation in shoots. The results showed that iron plaque was significantly increased with increasing Fe²⁺ concentrations in the solution culture. The amounts of P adsorbed on the iron plaque were increased significantly with external Fe²⁺ concentrations. Although shoot P concentration was not significantly affected by Fe²⁺ treatment after incubation for 2 days, it was significantly increased in the Fe‐treated plants compared with Fe‐deprived ones after incubation for 4 days. Soil culture experiment showed that the formation of iron plaque on root surfaces was promoted by exogenous iron, with greater amount of iron plaque being formed by addition of ferric hydroxide than of ferric oxide. Phosphorus adsorption on iron plaque also increased with the addition of iron oxides, and increasing soil P increased the amounts of P associated with the iron plaque and shoot P concentration. The amounts of iron plaque were almost sixfold higher under flooding condition than under field capacity condition. Plants pretreated under flooding condition generally had higher shoot P concentrations when they were transplanted to solutions with varying P levels, and this was most pronounced in the treatment with highest solution P concentration. The results suggest that iron plaque acts as a nutrient reservoir for phosphorus in the rhizosphere and helps enhance P acquisition by rice.