No abstract

Focal brain injury in the form of a needlestick (NS) results in cell death and induces a self-protective response flanking the lesion. Myo/Nog cells are identified by their expression of bone morphogenetic protein inhibitor Noggin, brain-specific angiogenesis inhibitor 1 (BAI1) and the skeletal muscle specific transcription factor MyoD. Myo/Nog cells limit cell death in two forms of retinopathy. In this study, we examined the acute response of Myo/Nog cells to a NS lesion that extended from the rat posterior parietal cortex to the hippocampus. Myo/Nog cells were identified with antibodies to Noggin and BAI1. These cells were the primary source of both molecules in the uninjured and injured brain. One day after the NS, the normally small population of Myo/Nog cells expanded approximately eightfold within a 1 mm area surrounding the lesion. Myo/Nog cells were reduced by approximately 50% along the lesion with an injection of the BAI1 monoclonal antibody and complement. The number of dying cells, identified by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), was unchanged at this early time point in response to the decrease in Myo/Nog cells. However, increasing the number of Myo/Nog cells within the lesion by injecting BAI1-positive (+) cells isolated from the brains of other animals, significantly reduced cell death and increased the number of NeuN+ neurons compared to brains injected with phosphate buffered saline or exogenous BAI1-negative cells. These findings demonstrate that Myo/Nog cells rapidly react to injury within the brain and increasing their number within the lesion is neuroprotective.

Climate change over the last four decades has resulted in a significant decline in streamflow in south-west Western Australia. In many streams in the region flows have reduced and perennial streams have become ephemeral. This has been accompanied by a decline in groundwater levels. To study this, a suite of five rainfall-runoff models was calibrated against observed flow in 106 gauged catchments across the region. A linear combination of two models, Sacramento and IHACRES, consistently resulted in a better model fit than any other combination of the individual models and this 'adopted model' was used to study catchment behaviour. In many of the catchments, there was a systematic and pervasive drift in model error during the latter period, indicating a change in state in the catchments that was not captured by the models. An assessment of the suitability of model structure is made on the basis of these results.