Microbial responses to changes in land use

Background/Question/Methods
Land use change is one of the greatest threats to biodiversity worldwide. This is especially true for land use change that results in the destruction of intact forest, or "deforestation”. Deforestation is causing a loss of biological diversity on an unprecedented scale, especially in the Tropics. It is unclear how the majority of the biodiversity on Earth – microbial biodiversity – is responding to these extraordinary rates of deforestation. I will provide an overview of our current understanding of microbial responses to deforestation. I will focus, as an example, on our current research regarding the effects of deforestation on the diversity of arbuscular mycorrhizal fungi (AMF), bacteria and archaea within Amazon Rainforest soils. This study takes advantage of an established chronosequence of primary rainforest, pastures of various ages, and secondary rainforest to determine the effect of deforestation on the taxonomic, phylogenetic and functional diversity of soil microorganisms, assayed using culture-independent methods.

Results/Conclusions
There is increasing evidence that deforestation significantly affects microbial diversity, and that “recovery” of microbial diversity in secondary forest soils is incomplete. For example, rarefaction curves suggest that the accumulation of AMF taxa is higher for Amazon primary forest soil relative to secondary forest soil. In addition, the community composition varies with land use; three AMF taxa were shared between primary and secondary forests, seven were found only in primary forest, and three were found exclusively in secondary forest soil. We also observed that the phylogenetic diversity of AMF is more reduced in secondary forest soils than expected given the regional pool of AMF taxa.

*The audio track for talks in this symposium may be obtained at the following web address:*

*https://sites.google.com/site/esa2010symposium13audiocontent/esa2010-symposium13-audio-content

A spin-coherent semiconductor photo-detector for quantum communication

We describe how quantum information may be transferred from photon polarization to electron spin in a semiconductor device. The transfer of quantum information relies on selection rules for optical transitions, such that two superposed photon polarizations excite two superposed spin states. Entanglement of the electron spin state with the spin state of the remaining hole is prevented by using a single, non-degenerate initial valence band. The degeneracy of the valence band is lifted by the combination of strain and a static magnetic field. We give a detailed description of a semiconductor structure that transfers photon polarization to electron spin coherently, and allows electron spins to be stored and to be made available for quantum information processing.Comment: To be published in the proceedings of the 11th International Winterschool on New Developments in Solid State Physics, 21 - 25 February, 2000, Mauterndorf, Austria (Physica E, Sept. 2000). 5 pages, 4 figures Revised with updated work on light-hole/heavy-hole selection rule

La construcción del conocimiento técnico en la dirección general de vivienda de la provincia de Córdoba

Fil: Pellizari, Lucila. Universidad Católica de Córdoba. Instituto de Ciencias de la Administración; Argentina

Microbial community and inorganic fluid analysis during CO2 storage within the frame of CO2SINK–Long-term experiments under in situ conditions

AbstractMicroorganisms play an important role in the transformation of material within the earth’s crust. The storage of CO2 could affect the composition of inorganic and organic components in the reservoir, consequently influencing microbial activities. To study the microbial induced processes together with geochemical, petrophysical and mineralogical changes, occurring during CO2 storage, long-term laboratory experiments under simulated reservoir P-T conditions were carried out. Clean inner core sections, obtained from the reservoir region at the CO2 storage site in Ketzin (Germany) from a depth of about 650 m, were incubated in high pressure vessels together with sterile synthetic formation brine under in situ P-T conditions of 5.5 MPa and 40 °C. A 16S rDNA based fingerprinting method was used to identify the dominant species in DNA extracts of pristine sandstone samples. Members of the α- and β-subdivisions of Proteobacteria and the Actinobacteria were identified. So far sequences belonging to facultative anaerobic, chemoheterotrophic bacteria (Burkholderia fungorum, Agrobacterium tumefaciens) gaining their energy from the oxidation of organic molecules and a genus also capable of chemolithoautotrophic growth (Hydrogenophaga) was identified.During CO2 incubation minor changes in the microbial community composition were observed. The majority of microbes were able to adapt to the changed conditions. During CO2 exposure increased concentrations of Ca2+, K+, Mg2+ and SO42− were observed. Partially, concentration rises are (i) due to equilibration between rock pore water and synthetic brine, and (ii) between rock and brine, and are thus independent on CO2 exposure. However, observed concentrations of Ca2+, K+, Mg2+ are even higher than in the original reservoir fluid and therefore indicate mineral dissolution due to CO2 exposure

Cambio de habitus en investigación en ciencias sociales a partir de la reforma de los 90 : Diferencias generacionales en las representaciones de los docentes-invetigadores en ciencias sociales sobre sus prácticas de investigación

Desde una perspectiva bourdeana analizamos la dinámica del campo académico después de la implementación del Programa de Incentivos en la década de los 90, tomando como objeto de análisis grupos de investigación del área de ciencias sociales de dos unidades académicas de la Universidad Nacional de Córdoba. Este artículo es un resumen parcial de una investigación sobre el capital curricular como el nuevo capital en juego del campo académico. En este artículo presentamos los resultados sobre las indagaciones en las representaciones de los docentes-investigadores e investigadores en formación de la UNC sobre las prácticas académicas específicas en ciencias sociales. En el estudio identificamos cuatro tipos de problemas que afectan al docente – investigador: problemas vinculados al habitus del investigador; problemas vinculados a la práctica docente; problemas vinculados a los recursos económicos; problemas vinculados a los sistemas de evaluación, que obliga a los investigadores a la acumulación de créditos para ir conformando un capital curricular, que los servirá para reposicionarse en el campo académico.Facultad de Periodismo y Comunicación Socia

Cambio de habitus en investigación en ciencias sociales a partir de la reforma de los 90 : Diferencias generacionales en las representaciones de los docentes-invetigadores en ciencias sociales sobre sus prácticas de investigación

Desde una perspectiva bourdeana analizamos la dinámica del campo académico después de la implementación del Programa de Incentivos en la década de los 90, tomando como objeto de análisis grupos de investigación del área de ciencias sociales de dos unidades académicas de la Universidad Nacional de Córdoba. Este artículo es un resumen parcial de una investigación sobre el capital curricular como el nuevo capital en juego del campo académico. En este artículo presentamos los resultados sobre las indagaciones en las representaciones de los docentes-investigadores e investigadores en formación de la UNC sobre las prácticas académicas específicas en ciencias sociales. En el estudio identificamos cuatro tipos de problemas que afectan al docente – investigador: problemas vinculados al habitus del investigador; problemas vinculados a la práctica docente; problemas vinculados a los recursos económicos; problemas vinculados a los sistemas de evaluación, que obliga a los investigadores a la acumulación de créditos para ir conformando un capital curricular, que los servirá para reposicionarse en el campo académico.Facultad de Periodismo y Comunicación Socia

Sterols and fecal indicator microorganisms in sediments from Admiralty Bay, Antarctica

Amostras de sedimento, coletadas nas proximidades da saída de esgoto da Estação Antártica Comandante Ferraz (Brasil), Antártica, foram medidos durante o verão de 1999/2000. As concentrações de esteróis totais e coprostanol variaram entre 0,09 e 19,6 ¼g.g-1 e < 0,01 e 14,0 ¼g.g-1 de sedimento seco. Nossas análises mostraram que apenas os pontos localizados até 400 m desde a saída de esgotos apresentaram contribuições provenientes do esgoto da estação brasileira. Baixos níveis de coprostanol e alta concentração de colesterol em pontos distantes puderam ser atribuídos a fontes naturais, como os mamíferos marinhos e organismos planctônicos. Indicadores microbiológicos (E. coli, streptococci fecais e Clostridium perfringens) não foram detectados até 50 m desde a saída de esgotos. Ambos indicadores de poluição fecal produziram dados consistentes, embora os esteróis fecais tenham sido mais apropriados para avaliar quantidades traço de material fecal. Este estudo concluiu que a contaminação por esgotos está limitada apenas aos pontos mais próximos da saída de esgoto. Em geral, as concentrações de esteróis fecais e indicadores microbiológicos foram menores do que em outras regiões antárticas e centros urbanos.Sediments from the proximity of Ferraz station outfall, located in Admiralty Bay, Antarctica, were analyzed for fecal indicator microorganisms and sterols during the austral summer of 1999/2000 in order to assess human sewage input. Concentrations of total sterols and coprostanol ranged from 0.09 to 19.6 ¼g.g-1 and < 0.01 and 14.0 ¼g.g-1 dry weight (dw), respectively. Our analyses indicated that only sites within to 400m of the sewage outfall exhibited a sterol signal characteristic of human sewage input. Low levels of coprostanol and high levels of cholesterol in distant sites could be attributed to natural sources such as marine mammals and planktonic organisms. Fecal indicator microorganisms (E. coli, fecal streptococci and Clostridium perfringens) were non-detectable beyond 50m from outfall. Both indicators (sterols and fecal indicator microorganisms) produced consistent data and fecal sterol parameters have sho wn themselves to be efficient in the evaluation of trace amounts of fecal material. This study concluded that sewage contamination is limited to the immediate vicinity of the sewage outfall. In general, the concentration of fecal sterols and microbiological indicators were lower than in other Antarctic areas

Prevalence of alkane monooxygenase genes in Arctic and Antarctic hydrocarbon-contaminated and pristine soils

The prevalence of four alkane monooxygenase genotypes (Pseudomonas putida GPo1, Pp alkB; Rhodococcus sp. strain Q15, Rh alkB1 and Rh alkB2; and Acinetobacter sp. strain ADP-1, Ac alkM) in hydrocarbon-contaminated and pristine soils from the Arctic and Antarctica were determined by both culture-independent (PCR hybridization analyses) and culture-dependent (colony hybridization analyses) molecular methods, using oligonucleotide primers and DNA probes specific for each of the alk genotypes. PCR hybridization of total soil community DNA detected the rhodococcal alkB genotypes in most of the contaminated (Rh alkB1, 18/20 soils; Rh alkB2, 13/20) and many pristine soils (Rh alkB1, 9/10 soils; Rh alkB2, 7/10), while Pp alkB was generally detected in the contaminated soils (15/20) but less often in pristine soils (5/10). Ac alkM was rarely detected in the soils (1/30). The colony hybridization technique was used to determine the prevalence of each of the alk genes and determine their relative abundance in culturable cold-adapted (5°C) and mesophilic populations (37°C) from eight of the polar soils. The cold-adapted populations, in general, possessed relatively higher percentages of the Rh alkB genotypes (Rh alkB1, 1.9% (0.55); Rh alkB2, 2.47% (0.89)), followed by the Pp alkB (1.13% (0.50)), and then the Ac alkM (0.53% (0.36)). The Rh alkB1 genotype was clearly more prevalent in culturable cold-adapted bacteria (1.9% (0.55)) than in culturable mesophiles (0.41 (0.55)), suggesting that cold-adapted bacteria are the predominant organisms possessing this genotype. Overall, these results indicated that (i) Acinetobacter spp. are not predominant members of polar alkane degradative microbial communities, (ii) Pseudomonas spp. may become enriched in polar soils following contamination events, and (iii) Rhodococcus spp. may be the predominant alkane-degradative bacteria in both pristine and contaminated polar soil