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171.
Rebecca Knight Caitlin E. Piette Hector Page Daniel Walters Elizabeth Marozzi Marko Nardini Simon Stringer Kathryn J. Jeffery 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2014,369(1635)
How the brain combines information from different sensory modalities and of differing reliability is an important and still-unanswered question. Using the head direction (HD) system as a model, we explored the resolution of conflicts between landmarks and background cues. Sensory cue integration models predict averaging of the two cues, whereas attractor models predict capture of the signal by the dominant cue. We found that a visual landmark mostly captured the HD signal at low conflicts: however, there was an increasing propensity for the cells to integrate the cues thereafter. A large conflict presented to naive rats resulted in greater visual cue capture (less integration) than in experienced rats, revealing an effect of experience. We propose that weighted cue integration in HD cells arises from dynamic plasticity of the feed-forward inputs to the network, causing within-trial spatial redistribution of the visual inputs onto the ring. This suggests that an attractor network can implement decision processes about cue reliability using simple architecture and learning rules, thus providing a potential neural substrate for weighted cue integration. 相似文献
172.
Felicity Claire Atkin Mark J. Dieters Joanne K. Stringer 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(3):555-565
Sugarcane breeders in Australia combine data across four selection programs to obtain estimates of breeding value for parents.
When these data are combined with full pedigree information back to founding parents, computing limitations mean it is not
possible to obtain information on all parents. Family data from one sugarcane selection program were analysed using two different
genetic models to investigate how different depths of pedigree and amount of data affect the reliability of estimating breeding
value of sugarcane parents. These were the parental and animal models. Additive variance components and breeding values estimated
from different amounts of information were compared for both models. The accuracy of estimating additive variance components
and breeding values improved as more pedigree information and historical data were included in analyses. However, adding years
of data had a much larger effect on the estimation of variance components of the population, and breeding values of the parents.
To accurately estimate breeding values of all sugarcane parents, a minimum of three generations of pedigree and 5 years of
historical data were required, while more information (four generations of pedigree and 7 years of historical data) was required
when identifying top parents to be selected for future cross pollination. 相似文献
173.
Danielle M. Stringer Peter Zahradka Vanessa C. DeClercq Natasha R. Ryz Robert Diakiw Laura L. Burr Xueping Xie Carla G. Taylor 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2010,1801(12):1375-1385
The isomer-specific effects of conjugated linoleic acid (CLA) on hepatic steatosis were assessed in fa/fa Zucker rats, a model for insulin resistance and the metabolic syndrome. Eight weeks of feeding trans-10,cis-12 CLA significantly improved glucose tolerance without changing body weight or visceral adipose mass. The trans-10,cis-12 isomer was also associated with reduced liver lipid content, improved liver function and reduced inflammation; these effects were not observed in rats fed the cis-9,trans-11 CLA isomer. Reduced liver lipid content did not correlate with activation of AMP-activated protein kinase or suppressed activation of sterol-regulatory element binding protein-1, two key regulators of hepatic lipid metabolism. Interestingly, rats fed cis-9,trans-11 CLA had fewer cytoplasmic lipid droplets in hepatocytes compared to rats fed control diet, but these droplets were larger in size. Conversely, fa/fa rats fed the trans-10,cis-12 CLA isomer had greater numbers of hepatic lipid droplets that were smaller in size, resulting in overall lower total lipid within these droplets. Changes in lipid droplets were associated with lower hepatic levels of PERILIPIN-2 (formerly known as adipophilin) in rats fed trans-10,cis-12 CLA, whereas amounts of other members of the PERILIPIN family of lipid droplet proteins were unaffected by dietary CLA. However, CLA isomers differentially affected the subcellular localization of these proteins. Treatment of H4IIE rat hepatoma cells with CLA isomers neither prevented nor reversed, but rather induced cytoplasmic lipid droplet formation, suggesting that the anti-steatotic effects of trans-10,cis-12 CLA are likely indirect and potentially mediated via increased lipid utilization by peripheral tissues. 相似文献
174.
175.
176.
Anthony Y. Stringer 《Journal of biological inorganic chemistry》2010,15(8):1175-1176
Obituary
Bert L. Vallee, “Mr. Zinc” (1919–2010) 相似文献177.
178.
Barbara L. Langille Josephine Hyde Kathleen M. Saint Tessa M. Bradford Danielle N. Stringer Simon M. Tierney William F. Humphreys Andrew D. Austin Steven J. B. Cooper 《Evolution; international journal of organic evolution》2021,75(1):166-175
Most subterranean animals are assumed to have evolved from surface ancestors following colonization of a cave system; however, very few studies have raised the possibility of “subterranean speciation” in underground habitats (i.e., obligate cave‐dwelling organisms [troglobionts] descended from troglobiotic ancestors). Numerous endemic subterranean diving beetle species from spatially discrete calcrete aquifers in Western Australia (stygobionts) have evolved independently from surface ancestors; however, several cases of sympatric sister species raise the possibility of subterranean speciation. We tested this hypothesis using vision (phototransduction) genes that are evolving under neutral processes in subterranean species and purifying selection in surface species. Using sequence data from 32 subterranean and five surface species in the genus Paroster (Dytiscidae), we identified deleterious mutations in long wavelength opsin (lwop), arrestin 1 (arr1), and arrestin 2 (arr2) shared by a sympatric sister‐species triplet, arr1 shared by a sympatric sister‐species pair, and lwop and arr2 shared among closely related species in adjacent calcrete aquifers. In all cases, a common ancestor possessed the function‐altering mutations, implying they were already adapted to aphotic environments. Our study represents one of the first confirmed cases of subterranean speciation in cave insects. The assessment of genes undergoing pseudogenization provides a novel way of testing modes of speciation and the history of diversification in blind cave animals. 相似文献
179.
Kate A. Williamson Andrew Hamilton John A. Reynolds Peter Sipos Ian Crocker Sally E. Stringer Yvonne M. Alexander 《Aging cell》2013,12(1):139-147
Aging poses one of the largest risk factors for the development of cardiovascular disease. The increased propensity toward vascular pathology with advancing age maybe explained, in part, by a reduction in the ability of circulating endothelial progenitor cells to contribute to vascular repair and regeneration. Although there is evidence to suggest that colony forming unit‐Hill cells and circulating angiogenic cells are subject to age‐associated changes that impair their function, the impact of aging on human outgrowth endothelial cell (OEC) function has been less studied. We demonstrate that OECs isolated from cord blood or peripheral blood samples from young and old individuals exhibit different characteristics in terms of their migratory capacity. In addition, age‐related structural changes were discovered in OEC heparan sulfate (HS), a glycocalyx component that is essential in many signalling pathways. An age‐associated decline in the migratory response of OECs toward a gradient of VEGF significantly correlated with a reduction in the relative percentage of the trisulfated disaccharide, 2‐O‐sulfated‐uronic acid, N, 6‐O‐sulfated‐glucosamine (UA[2S]‐GlcNS[6S]), within OEC cell surface HS polysaccharide chains. Furthermore, disruption of cell surface HS reduced the migratory response of peripheral blood‐derived OECs isolated from young subjects to levels similar to that observed for OECs from older individuals. Together these findings suggest that aging is associated with alterations in the fine structure of HS on the cell surface of OECs. Such changes may modulate the migration, homing, and engraftment capacity of these repair cells, thereby contributing to the progression of endothelial dysfunction and age‐related vascular pathologies. 相似文献
180.
Hazem J. Abuhusain Azadeh Matin Qiao Qiao Han Shen Nupur Kain Bryan W. Day Brett W. Stringer Benjamin Daniels Maarit A. Laaksonen Charlie Teo Kerrie L. McDonald Anthony S. Don 《The Journal of biological chemistry》2013,288(52):37355-37364
Studies in cell culture and mouse models of cancer have indicated that the soluble sphingolipid metabolite sphingosine 1-phosphate (S1P) promotes cancer cell proliferation, survival, invasiveness, and tumor angiogenesis. In contrast, its metabolic precursor ceramide is prodifferentiative and proapoptotic. To determine whether sphingolipid balance plays a significant role in glioma malignancy, we undertook a comprehensive analysis of sphingolipid metabolites in human glioma and normal gray matter tissue specimens. We demonstrate, for the first time, a systematic shift in sphingolipid metabolism favoring S1P over ceramide, which increases with increasing cancer grade. S1P content was, on average, 9-fold higher in glioblastoma tissues compared with normal gray matter, whereas the most abundant form of ceramide in the brain, C18 ceramide, was on average 5-fold lower. Increased S1P content in the tumors was significantly correlated with increased sphingosine kinase 1 (SPHK1) and decreased sphingosine phosphate phosphatase 2 (SGPP2) expression. Inhibition of S1P production by cultured glioblastoma cells, using a highly potent and selective SPHK1 inhibitor, blocked angiogenesis in cocultured endothelial cells without affecting VEGF secretion. Our findings validate the hypothesis that an altered ceramide/S1P balance is an important feature of human cancers and support the development of SPHK1 inhibitors as antiangiogenic agents for cancer therapy. 相似文献