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Biology subjects

White, A.

Publications and source records attributed to White, A..

2 recordsLinked to original sources

Industrial bees: when agricultural intensification doesn’t impact local disease prevalence

O_LIAlthough it is generally thought that the intensification of farming will result in higher disease prevalences there is little specific modelling testing this idea. We build multi-colony models to inform how apicultural intensification is predicted to impact honeybee pathogen epidemiology at the apiary scale.\nC_LIO_LICounter to the prevailing view, our models predict that intensification, captured though increased population sizes, changes in population network structure, and increased between-colony transmission, is likely to have little effect on disease prevalence within an apiary.\nC_LIO_LIThe greatest impacts of intensification are found for diseases with relatively low R0 (basic reproduction number), however, such diseases cause little overall disease prevalence and therefore the impacts of intensification are minor. Furthermore, the smallest impacts of intensification are found for diseases with high R0 values, which we argue are typical of important honeybee diseases.\nC_LIO_LIPolicy Implications: Our findings highlight a lack of support for the hypothesis that current and ongoing intensification leads to notably higher disease prevalences. More broadly, our work demonstrates the need for informative models of agricultural systems and management practices in order to understand the implications of management changes on diseases.\nC_LI

epidemiology

Human POMC processing in vitro and in vivo revealed by quantitative peptidomics

Human obesity can result from the aberrant production or processing of proopiomelanocortin (POMC) in hypothalamic neurons, but it is unclear which human POMC-derived peptides are most relevant to body weight regulation. To address this question, we analysed both hypothalamic neurons derived from human pluripotent stem cells (hPSCs) and primary human hypothalamic tissue using quantitative liquid chromatography tandem mass spectroscopy (LC-MS/MS). In both in vitro- and in vivo-derived samples, we found that POMC was processed into {beta}-melanocyte stimulating hormone ({beta}-MSH), whose existence in the human brain has been controversial. {beta}-MSH and desacetyl -MSH (d--MSH) were produced at roughly equimolar concentrations and in vast excess to acetylated -MSH (5-to 200-fold), suggesting that the importance of both d--MSH and {beta}-MSH to human obesity has been underestimated. Since body weight is sensitive to changes in MSH concentration, we asked whether hPSC-derived hypothalamic neurons could provide mechanistic insights into the processing and secretion of MSH peptides. We found that cultured human hypothalamic neurons appropriately trafficked POMC and its derivatives, and robustly (P<0.0001) secreted them when depolarised. Furthermore, the adipocyte-derived hormone leptin significantly (P<0.01) promoted their production of both d--MSH and {beta}-MSH. These results establish hPSC-derived hypothalamic neurons as a model system for studying human-specific aspects of POMC processing that might be therapeutically harnessed to treat obesity.

neuroscience