Freshwater Pearl Mussel (Margaritifera Margaritifera) Host Choice and Behavioural Responses to Changes in Flow Regime

The endangered freshwater pearl mussel (Margaritifera margaritifera), one of the longest-lived invertebrates, are threatened globally. Scotland, UK, remains a stronghold, however even here the population is declining due to factors such as habitat degradation, pollution and pearl fishing. The study comprised two parts: field surveys of glochidia infection of host salmonid fish, and a novel laboratory flume based study of the mussel‟s behavioral responses to changes in flow regime. The intricate life cycle of M.margaritifera includes a parasitic stage as glochidia attached to gills of salmonids. The preferred host in Scotland is thought to be Salmo salar and Salmo trutta in the absence of S.salar. This has not, however, been empirically tested in the field. Eight rivers in NW Scotland were surveyed using standard electrofishing techniques and encysted glochidia counted. Results suggest S.trutta is the primary host fish for glochidia attachment in the rivers surveyed, which contradicts current accepted knowledge about host specificity of M.margaritifera. Mussel populations are often found in regulated rivers, however little data exists on response to changes in flow regime. The mussel's behavioral response to changes in flow were investigated in an experimental flume. Mussels buried significantly deeper in conditions of gradually increasing water velocity compared with rapid increases or where water velocity was constant. 68% of individual mussels washed out when the water velocity was rapidly increased. The findings are novel, provide initial recommendations for targeted management actions for the conservation of M.margaritifera both in Scotland and internationally, and highlight more research is required

Upregulation of endocytic protein expression in the Alzheimer’s disease male human brain

Amyloid-beta (Aβ) is produced from amyloid precursor protein (APP) primarily after APP is internalised by endocytosis and clathrin-mediated endocytic processes are altered in Alzheimer’s disease (AD). There is also evidence that cholesterol and flotillin affect APP endocytosis. We hypothesised that endocytic protein expression would be altered in the brains of people with AD compared to non-diseased subjects which could be linked to increased Aβ generation. We compared protein expression in frontal cortex samples from men with AD compared to age-matched, non-diseased controls. Soluble and insoluble Aβ40 and Aβ42, the soluble Aβ42/Aβ40 ratio, βCTF, BACE1, presenilin-1 and the ratio of phosphorylated:total GSK3β were significantly increased while the insoluble Aβ42:Aβ40 ratio was significantly decreased in AD brains. Total and phosphorylated tau were markedly increased in AD brains. Significant increases in clathrin, AP2, PICALM isoform 4, Rab-5 and caveolin-1 and 2 were seen in AD brains but BIN1 was decreased. However, using immunohistochemistry, caveolin-1 and 2 were decreased. The results obtained here suggest an overall increase in endocytosis in the AD brain, explaining, at least in part, the increased production of Aβ during AD