STORRE Community: This community contains the ePrints and eTheses produced by the Aquaculture staff and students.

Molecular and functional characterization of a fads2 orthologue in the Amazonian teleost, Arapaima gigas

Sun, 01 Jan 2017 00:00:00 GMT

Title: Molecular and functional characterization of a fads2 orthologue in the Amazonian teleost, Arapaima gigas Authors: Lopes-Marques, Mónica; Ozório, Rodrigo; Amaral, Ricardo; Tocher, Douglas R; Monroig, Oscar; Costa, Castro Luıs Filipe Abstract: The Brazilian teleost Arapaima gigas is an iconic species of the Amazon. In recent years a significant effort has been put into the farming of arapaima to mitigate overfishing threats. However, little is known regarding the nutritional requirements of A. gigas in particular those for essential fatty acids including the long-chain polyunsaturated fatty acids (LC-PUFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The ability to biosynthesize LC-PUFA is dependent upon the gene repertoire of fatty acyl desaturases (Fads) and elongases (Elovl), as well as their fatty acid specificities. In the present study we characterized both molecularly and functionally an orthologue of the desaturase fatty acid desaturase 2 (fads2) from A. gigas. The isolated sequence displayed the typical desaturase features, a cytochrome b5-domain with the heme-binding motif, two transmembrane domains and three histidine-rich regions. Functional characterization of A. gigas fads2 showed that, similar to other teleosts, the A. gigas fads2 exhibited a predominant Δ6 activity complemented with some capacity for Δ8 desaturation. Given that A. gigas belongs to one of the oldest teleostei lineages, the Osteoglossomorpha, these findings offer a significant insight into the evolution LC-PUFA biosynthesis in teleosts.

Quantifying the roles of host movement and vector dispersal in the transmission of vector-borne diseases of livestock

Mon, 03 Apr 2017 00:00:00 GMT

Title: Quantifying the roles of host movement and vector dispersal in the transmission of vector-borne diseases of livestock Authors: Sumner, Tom; Orton, Richard; Green, Darren; Kao, Rowland R; Gubbins, Simon Abstract: The role of host movement in the spread of vector-borne diseases of livestock has been little studied. Here we develop a mathematical framework that allows us to disentangle and quantify the roles of vector dispersal and livestock movement in transmission between farms. We apply this framework to outbreaks of bluetongue virus (BTV) and Schmallenberg virus (SBV) in Great Britain, both of which are spread byCulicoidesbiting midges and have recently emerged in northern Europe. For BTV we estimate parameters by fitting the model to outbreak data using approximate Bayesian computation, while for SBV we use previously derived estimates. We find that around 90% of transmission of BTV between farms is a result of vector dispersal, while for SBV this proportion is 98%. This difference is a consequence of higher vector competence and shorter duration of viraemia for SBV compared with BTV. For both viruses we estimate that the mean number of secondary infections per infected farm is greater than one for vector dispersal, but below one for livestock movements. Although livestock movements account for a small proportion of transmission and cannot sustain an outbreak on their own, they play an important role in establishing new foci of infection. However, the impact of restricting livestock movements on the spread of both viruses depends critically on assumptions made about the distances over which vector dispersal occurs. If vector dispersal occurs primarily at a local scale (99% of transmission occurs <25 km), movement restrictions are predicted to be effective at reducing spread, but if dispersal occurs frequently over longer distances (99% of transmission occurs <50 km) they are not.

DHA Supplementation Alone or in Combination with Other Nutrients Does not Modulate Cerebral Hemodynamics or Cognitive Function in Healthy Older Adults

Tue, 09 Feb 2016 00:00:00 GMT

Title: DHA Supplementation Alone or in Combination with Other Nutrients Does not Modulate Cerebral Hemodynamics or Cognitive Function in Healthy Older Adults Authors: Jackson, Philippa A; Forster, Joanne S; Bell, J Gordon; Dick, James R; Younger, Irene; Kennedy, David O Abstract: A number of recent trials have demonstrated positive effects of dietary supplementation with the omega-3 polyunsaturated fatty acids ( n-3 PUFAs), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on measures of cognitive function in healthy young and older adults. One potential mechanism by which EPA, and DHA in particular, may exert these effects is via modulation of cerebral hemodynamics. In order to investigate the effects of DHA alone or provided as one component of a multinutrient supplement (also including Gingko biloba, phosphatidylserine and vitamins B9 and B12) on measures of cerebral hemodynamics and cognitive function, 86 healthy older adults aged 50–70 years who reported subjective memory deficits were recruited to take part in a six month daily dietary supplementation trial. Relative changes in the concentration of oxygenated hemoglobin and deoxygenated hemoglobin were assessed using Near Infrared Spectroscopy (NIRS) during the performance of cognitive tasks prior to and following the intervention period. Performance on the cognitive tasks was also assessed. No effect of either active treatment was found for any of the NIRS measures or on the cognitive performance tasks, although the study was limited by a number of factors. Further work should continue to evaluate more holistic approaches to cognitive aging.

Pathogenesis of experimental salmonid alphavirus infection in vivo: an ultrastructural insight

Fri, 08 Jan 2016 00:00:00 GMT

Title: Pathogenesis of experimental salmonid alphavirus infection in vivo: an ultrastructural insight Authors: Herath, Tharangani; Ferguson, Hugh; Weidmann, Manfred; Bron, James; Thompson, Kim D; Adams, Alexandra; Muir, Katherine; Richards, Randolph Abstract: Salmonid alphavirus (SAV) is an enveloped, single-stranded, positive sense RNA virus belonging to the familyTogaviridae. It causes economically devastating disease in cultured salmonids. The characteristic features of SAV infection include severe histopathological changes in the heart, pancreas and skeletal muscles of diseased fish. Although the presence of virus has been reported in a wider range of tissues, the mechanisms responsible for viral tissue tropism and for lesion development during the disease are not clearly described or understood. Previously, we have described membrane-dependent morphogenesis of SAV and associated apoptosis-mediated cell death in vitro. The aims of the present study were to explore ultrastructural changes associated with SAV infection in vivo. Cytolytic changes were observed in heart, but not in gill and head-kidney of virus-infected fish, although they still exhibited signs of SAV morphogenesis. Ultrastructural changes associated with virus replication were also noted in leukocytes in the head kidney of virus-infected fish. These results further describe the presence of degenerative lesions in the heart as expected, but not in the gills and in the kidney.