Physical soil architectural traits are functionally linked to carbon decomposition and bacterial diversity.

Aggregates play a key role in protecting soil organic carbon (SOC) from microbial decomposition. The objectives of this study were to investigate the influence of pore geometry on the organic carbon decomposition rate and bacterial diversity in both macro- (250-2000 µm) and micro-aggregates (53-250 µm) using field samples. Four sites of contrasting land use on Alfisols (i.e. native pasture, crop/pasture rotation, woodland) were investigated. 3D Pore geometry of the micro-aggregates and macro-aggregates were examined by X-ray computed tomography (µCT). The occluded particulate organic carbon (oPOC) of aggregates was measured by size and density fractionation methods. Micro-aggregates had 54% less µCT observed porosity but 64% more oPOC compared with macro-aggregates. In addition, the pore connectivity in micro-aggregates was lower than macro-aggregates. Despite both lower µCT observed porosity and pore connectivity in micro-aggregates, the organic carbon decomposition rate constant (Ksoc) was similar in both aggregate size ranges. Structural equation modelling showed a strong positive relationship of the concentration of oPOC with bacterial diversity in aggregates. We use these findings to propose a conceptual model that illustrates the dynamic links between substrate, bacterial diversity, and pore geometry that suggests a structural explanation for differences in bacterial diversity across aggregate sizes.

Proteomic assessment of host-associated microevolution in the fungus Thielaviopsis basicola.

Thielaviopsis basicola, a soil-borne pathogen with a broad host range and a cosmopolitan distribution, is emerging as a major risk to sustainable cotton production in Australia. Previous studies suggested that host specialization has occurred making T. basicola an ideal model for a comparative proteomic analysis of strains isolated from different hosts. Elucidation of the genomic diversity and investigation of the functional differences in the Australian population could provide valuable information towards disease control. In this study, isolates of T. basicola were investigated for genomic (internal transcribed spacers region), proteomic and cotton virulence level variations. Internal transcribed spacers sequence analysis revealed that isolates are grouped based on host of origin irrespective of geographical origin. At the proteome level a degree of diversity was apparent and hierarchical clustering analysis of the data also demonstrated a close correlation between the proteome and the host of origin. LC-MS/MS analysis and identification using cross-species similarity searching and de novo sequencing of host-specific differentially expressed proteins and the virulence-correlated proteome allowed successful identification of 43 spots. The majority were found to be involved in metabolism. Spots that were correlated with host and virulence differences included a hypothetical protein with a Rossman-fold NAD(P)(+)-binding protein domain, glyceraldehyde-3-phosphate dehydrogenase, arginase and tetrahydroxynaphthalene reductase.

Síndrome de cushing por hiperplasia adrenal macronodular bilateral ACTH-independiente / Cushing's syndrome due to ACTH-independent bilateral macronodular adrenal hyperplasia

La hiperplasia suprarrenal macronodular bilateral ACTH-independiente (HAMAI) se considera hoy día una entidad diferente y separada del resto de causas de síndrome de Cushing. Su etiología es incierta aunque en los últimos años se ha demostrado la existencia de respuesta anormal de glándulas suprarrenales a distintas hormonas que estimulan la secreción de cortisol. En este artículo presentamos un caso de hipercortisolismo no suprimible con dexametasona, cifras de ACTH indetectables, hiperplasia suprarrenal bilateral de aspecto nodular y resonancia magnética nuclear hipofisaria normal. Se realizó suprarrenalectomía bilateral, objetivando cifras detectables de ACTH a los 3 meses (AU)