The Experts below are selected from a list of 474 Experts worldwide ranked by ideXlab platform
Kenneth B Storey - One of the best experts on this subject based on the ideXlab platform.
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Estivation responsive micrornas in a hypometabolic terrestrial snail
PeerJ, 2019Co-Authors: Myriam P Hoyeck, Hanane Hadjmoussa, Kenneth B StoreyAbstract:When faced with extreme environmental conditions, the milk snail (Otala lactea) enters a state of dormancy known as Estivation. This is characterized by a strong reduction in metabolic rate to <30% of normal resting rate that is facilitated by various behavioural, physiological, and molecular mechanisms. Herein, we investigated the regulation of microRNA in the induction of Estivation. Changes in the expression levels of 75 highly conserved microRNAs were analysed in snail foot muscle, of which 26 were significantly upregulated during Estivation compared with controls. These Estivation-responsive microRNAs were linked to cell functions that are crucial for long-term survival in a hypometabolic state including anti-apoptosis, cell-cycle arrest, and maintenance of muscle functionality. Several of the microRNA responses by snail foot muscle also characterize hypometabolism in other species and support the existence of a conserved suite of miRNA responses that regulate environmental stress responsive metabolic rate depression across phylogeny.
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The potential contribution of miRNA-200-3p to the fatty acid metabolism by regulating AjEHHADH during aEstivation in sea cucumber.
PeerJ, 2018Co-Authors: Muyan Chen, Kenneth B Storey, Shanshan Wang, Xiumei ZhangAbstract:The sea cucumber (Apostichopus japonicus) has become a good model organism for studying environmentally-induced aEstivation by a marine invertebrate more recently. In the present study, we hypothesized that miRNA-200-3p may contribute to establish rapid biological control to regulate fatty acid metabolism during a Estivation. The peroxisomal bi-functional enzyme (EHHADH) is a crucial participant of the classical peroxisomal fatty acid β-oxidation pathway, the relative mRNA transcripts and protein expressions of EHHADH were analyzed in intestine from sea cucumbers experienced long-term aEstivation. Both mRNA transcripts and protein expressions of EHHADH in intestine decreased significantly during deep-aEstivation as compared with non-aEstivation controls. Analysis of the 3' UTR of AjEHHADH showed the presence of a conserved binding site for miR-200-3p. Level of miR-200-3p showed an inverse correlation with EHHADH mRNA transcripts and protein levels in intestine, implicating miR-200-3p may directly targeted AjEHHADH by inducing the degradation of AjEHHADH mRNA in the aestivating sea cucumber, further dual-luciferase reporter assay validated the predicted role of miRNA-200-3p in regulating AjEHHADH. In order to further understand their regulatory mechanism, we conducted the functional experiment in vivo. The overexpression of miR-200-3p in sea cucumber significantly decreased mRNA and protein expression levels of AjEHHADH. Taken together, these findings suggested the potential contribution of miRNA-200-3p to the fatty acid metabolism by regulating AjEHHADH during aEstivation in sea cucumber.
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understanding mechanism of sea cucumber apostichopus japonicus aEstivation insights from tmt based proteomic study part d genomics and proteomics
Comparative Biochemistry and Physiology, 2016Co-Authors: Muyan Chen, Kenneth B Storey, Aijun Zhu, Lina Sun, Tianxiang Gao, Tianming WangAbstract:Marine invertebrate aEstivation is a unique strategy for summer survival in response to hot marine conditions. The sea cucumber, Apostichopus japonicus, is an excellent model marine invertebrate for studies of environmentally-induced aEstivation. In the present study, we used a tandem mass tag (TMT)-coupled LC-MS/MS approach to identify and quantify the global proteome expression profile over the aEstivation-arousal cycle of A. japonicus. A total of 3920 proteins were identified from the intestine of sea cucumber. Among them, 630 proteins showed significant differential expression when comparing three conditions of sea cucumbers: non-aestivating (active), deep-aEstivation (at least 15days of continuous aEstivation), and arousal after aEstivation (renewed moving and feeding). Sea cucumbers in deep aEstivation showed substantial differentially expressed proteins (143 up-regulated and 267 down-regulated proteins compared with non-aestivating controls). These differentially expressed proteins suggested that protein and phospholipid probably are major fuel sources during hypometabolism and a general attenuation of carbohydrate metabolism was observed during deep aEstivation. Differentially expressed proteins also provided the first global picture of a shift in protein synthesis, protein folding, DNA binding, apoptosis, cellular transport and signaling, and cytoskeletal proteins during deep aEstivation in sea cucumbers. A comparison of arousal from aEstivation with deep aEstivation, revealed a general reversal of the changes that occurred in aEstivation for most proteins. Western blot detection further validated the significant up-regulation of HSP70 and down-regulation of methyltransferase-like protein 7A-like in deep-aEstivation. Our results suggest that there is substantial post-transcriptional regulation of proteins during the aEstivation-arousal cycle in sea cucumbers.
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differential gene expression in the respiratory tree of the sea cucumber apostichopus japonicus during aEstivation
Marine Genomics, 2014Co-Authors: Ye Zhao, Kenneth B Storey, Hongsheng Yang, Muyan ChenAbstract:Sea cucumbers, Apostichopus japonicus, experience seasonally high water temperatures during the summer months and enter aEstivation to survive. AEstivation is characterized by strong metabolic rate depression which is supported by a series of strategies including reorganizing metabolic processes, suppressing cell functions, enhancing cytoprotective mechanisms, and altered gene expression. The respiratory tree tissue of the sea cucumber is an excellent material for studying aEstivation, undergoing obvious atrophy during aEstivation. The present study analyzed the global gene expression profile of respiratory tree tissue of A. japonicus during aEstivation by constructing and screening three libraries representing key stages of aEstivation: non-aEstivation (NA), deep-aEstivation (DA), and arousal from aEstivation (M) using RNA-seq. A total of 1240, 1184 and 303 differentially expressed genes (DEGs) were identified following the criteria of [log(2) ratiol >= 1 and FDR <= 0.001 in comparisons of DA vs. NA, AA vs. NA and DA vs. AA. A set of respiratory tree specific DEGs was identified the first time and, in addition, common DEGs that were responsive to aEstivation in both respiratory tree and intestine were identified. Functional analysis of DEGs was further performed by GO enrichment analysis and respiratory tree specific GO terms were screened out and provide interesting hints for further studies of the molecular regulation of aEstivation in A. japonicus. (c) 2014 Elsevier B.V. All rights reserved.
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Regulation of global protein translation and protein degradation in aerobic dormancy
Molecular and Cellular Biochemistry, 2009Co-Authors: Christopher J. Ramnanan, Marcus E. Allan, Amy G. Groom, Kenneth B StoreyAbstract:We hypothesized that protein turnover would be substantially suppressed during Estivation in the land snail, Otala lactea , as part of a wholesale move to conserve ATP in the hypometabolic state, and that decreased rates of protein synthesis and degradation would be mediated by altering the phosphorylation state of key proteins. Rates of protein translation, measured in vitro, decreased by ~80% in extracts of foot muscle and hepatopancreas after 2 days of Estivation, and this reduction was associated with strong increases in the phosphorylation of ribosomal factors, eIF2α and eEF2, as well as decreased phosphorylation of 4E-BP1. Reductions in levels of markers of ribosomal biogenesis and a tissue-specific reduction in the phosphorylation state of eIF4E and eIF4GI were also evident after 14 days of Estivation. Activity of the 20S proteasome decreased by 60–80% after 2 days of Estivation and this decrease was mediated by protein kinase G in vitro, whereas protein phosphatase 2A activated the proteasome. Levels of protein carbonyls did not change in snail tissues during Estivation whereas the expression heat shock proteins increased, suggesting that protein resistance to damage is enhanced in Estivation. In conclusion, protein synthesis and degradation rates were coordinately suppressed during Estivation in O. lactea and this is associated with the phosphorylation of ribosomal initiation and elongation factors and the 20S proteasome.
Masaaki Ikehara - One of the best experts on this subject based on the ideXlab platform.
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High Accuracy Image Rotation and Scale Estimation Using Radon Transform and Sub-pixel Shift Estimation
ICASSP 2019 - 2019 IEEE International Conference on Acoustics Speech and Signal Processing (ICASSP), 2019Co-Authors: Takanori Fujisawa, Masaaki IkeharaAbstract:Rotation and scale estimation of images are fundamental tasks in image registration. The conventional estimation method uses log-polar transform and 1D shift estimation to estimate rotation and scale regardless of the shift of images. However, this transform requires interpolation of the frequency components, which causes estimation error. We propose a rotation and scale estimation algorithm based on Radon transform and sub-pixel shift estimation. Radon transform can estimate the rotation independent of the shift and can reduce the influence of interpolation error because it is performed on the spatial image rather than the frequency. In addition, sub-pixel shift estimation using linear approximation of the phase component improves the precision of 1D shift estimation and achieves accurate rotation estimation. The proposed method was evaluated on test images, and the results demonstrate that the proposed method accurately estimates rotation compared to log-polar-based and other conventional methods.
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High-Accuracy Image Rotation and Scale Estimation Using Radon Transform and Sub-Pixel Shift Estimation
IEEE Access, 2019Co-Authors: Takanori Fujisawa, Masaaki IkeharaAbstract:Rotation and scale estimation of images are fundamental tasks in image registration. The conventional estimation method uses log-polar transform and 1D shift estimation to estimate rotation and scale regardless of the shift of images. However, this transform requires interpolation of the frequency components, which causes estimation error. We propose a rotation and scale estimation algorithm based on the Radon transform and sub-pixel shift estimation. The Radon transform can estimate the rotation independent of the shift and can reduce the influence of interpolation error. In addition, sub-pixel shift estimation using a linear approximation of the phase component improves the precision of 1D shift estimation and achieves accurate rotation estimation. The proposed method was evaluated on test images, and the results demonstrate that the proposed method has higher accuracy compared with the log-polar transform.
Danijela Cabric - One of the best experts on this subject based on the ideXlab platform.
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primary user traffic estimation for dynamic spectrum access
IEEE Journal on Selected Areas in Communications, 2013Co-Authors: Wesam Gabran, Przemyslaw Pawelczak, Danijela CabricAbstract:This paper presents a mathematical analysis of the accuracy of estimating Primary User's (PU's) mean duty cycle u, as well as the mean off- and on-times, where the estimation accuracy is expressed in terms of the Cramer-Rao bound on the mean squared estimation error. For estimating u, we derive the mean squared estimation error for uniform, non-uniform, and weighted sample stream averaging, as well as maximum likelihood (ML) estimation. The estimation accuracy of the mean PU off- and on-times is studied when ML estimation is employed. Besides, the impact of spectrum sensing errors on the estimation accuracy is studied analytically for the averaging estimators, while simulation results are used for the ML estimators. Furthermore, we develop algorithms for the blind estimation of the traffic parameters based on the derived theoretical estimation accuracy expressions.
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primary user traffic estimation for dynamic spectrum access
arXiv: Networking and Internet Architecture, 2012Co-Authors: Wesam Gabran, Przemyslaw Pawelczak, Danijela CabricAbstract:Accurate estimation of licensed channel Primary User's (PU) temporal statistics is important for Dynamic Spectrum Access (DSA) systems. With accurate estimation of the mean duty cycle, u, and the mean off- and on-times of PUs, DSA systems can more efficiently assign PU resources to its subscribers, thus, increasing channel utilization. This paper presents a mathematical analysis of the accuracy of estimating u, as well as the PU mean off- and on-times, where the estimation accuracy is expressed as the mean squared estimation error. The analysis applies for the traffic model assuming exponentially distributed PU off- and on-times, which is a common model in traffic literature. The estimation accuracy is quantified as a function of the number of samples and observation window length, hence, this work provides guidelines on traffic parameters estimation for both energy-constrained and delay-constrained applications. For estimating u, we consider uniform, non-uniform, and weighted sample stream averaging, as well as maximum likelihood estimation. The estimation accuracy of the mean PU off- and on-times is studied when maximum likelihood estimation is employed. Furthermore, we develop algorithms for the blind estimation of the traffic parameters based on the derived theoretical estimation accuracy expressions. We show that the estimation error for all traffic parameters is lower bounded for a fixed observation window length due to the correlation between the traffic samples. Moreover, we prove that for estimating u, maximum likelihood estimation can yield the same estimation error as weighted sample averaging using only half the observation window length.
Takanori Fujisawa - One of the best experts on this subject based on the ideXlab platform.
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High Accuracy Image Rotation and Scale Estimation Using Radon Transform and Sub-pixel Shift Estimation
ICASSP 2019 - 2019 IEEE International Conference on Acoustics Speech and Signal Processing (ICASSP), 2019Co-Authors: Takanori Fujisawa, Masaaki IkeharaAbstract:Rotation and scale estimation of images are fundamental tasks in image registration. The conventional estimation method uses log-polar transform and 1D shift estimation to estimate rotation and scale regardless of the shift of images. However, this transform requires interpolation of the frequency components, which causes estimation error. We propose a rotation and scale estimation algorithm based on Radon transform and sub-pixel shift estimation. Radon transform can estimate the rotation independent of the shift and can reduce the influence of interpolation error because it is performed on the spatial image rather than the frequency. In addition, sub-pixel shift estimation using linear approximation of the phase component improves the precision of 1D shift estimation and achieves accurate rotation estimation. The proposed method was evaluated on test images, and the results demonstrate that the proposed method accurately estimates rotation compared to log-polar-based and other conventional methods.
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High-Accuracy Image Rotation and Scale Estimation Using Radon Transform and Sub-Pixel Shift Estimation
IEEE Access, 2019Co-Authors: Takanori Fujisawa, Masaaki IkeharaAbstract:Rotation and scale estimation of images are fundamental tasks in image registration. The conventional estimation method uses log-polar transform and 1D shift estimation to estimate rotation and scale regardless of the shift of images. However, this transform requires interpolation of the frequency components, which causes estimation error. We propose a rotation and scale estimation algorithm based on the Radon transform and sub-pixel shift estimation. The Radon transform can estimate the rotation independent of the shift and can reduce the influence of interpolation error. In addition, sub-pixel shift estimation using a linear approximation of the phase component improves the precision of 1D shift estimation and achieves accurate rotation estimation. The proposed method was evaluated on test images, and the results demonstrate that the proposed method has higher accuracy compared with the log-polar transform.
Christopher J. Ramnanan - One of the best experts on this subject based on the ideXlab platform.
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Regulation of global protein translation and protein degradation in aerobic dormancy
Molecular and Cellular Biochemistry, 2009Co-Authors: Christopher J. Ramnanan, Marcus E. Allan, Amy G. Groom, Kenneth B StoreyAbstract:We hypothesized that protein turnover would be substantially suppressed during Estivation in the land snail, Otala lactea , as part of a wholesale move to conserve ATP in the hypometabolic state, and that decreased rates of protein synthesis and degradation would be mediated by altering the phosphorylation state of key proteins. Rates of protein translation, measured in vitro, decreased by ~80% in extracts of foot muscle and hepatopancreas after 2 days of Estivation, and this reduction was associated with strong increases in the phosphorylation of ribosomal factors, eIF2α and eEF2, as well as decreased phosphorylation of 4E-BP1. Reductions in levels of markers of ribosomal biogenesis and a tissue-specific reduction in the phosphorylation state of eIF4E and eIF4GI were also evident after 14 days of Estivation. Activity of the 20S proteasome decreased by 60–80% after 2 days of Estivation and this decrease was mediated by protein kinase G in vitro, whereas protein phosphatase 2A activated the proteasome. Levels of protein carbonyls did not change in snail tissues during Estivation whereas the expression heat shock proteins increased, suggesting that protein resistance to damage is enhanced in Estivation. In conclusion, protein synthesis and degradation rates were coordinately suppressed during Estivation in O. lactea and this is associated with the phosphorylation of ribosomal initiation and elongation factors and the 20S proteasome.
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suppression of na k atpase activity during Estivation in the land snail otala lactea
The Journal of Experimental Biology, 2006Co-Authors: Christopher J. Ramnanan, Kenneth B StoreyAbstract:SUMMARY Entry into the hypometabolic state of Estivation requires a coordinated suppression of the rate of cellular ATP turnover, including both ATP-generating and ATP-consuming reactions. As one of the largest consumers of cellular ATP, the plasma membrane Na + /K + -ATPase is a potentially key target for regulation during Estivation. Na + /K + -ATPase was investigated in foot muscle and hepatopancreas of the land snail Otala lactea , comparing active and estivating states. In both tissues enzyme properties changed significantly during Estivation: maximal activity was reduced by about one-third, affinity for Mg.ATP was reduced ( K m was 40% higher), and activation energy (derived from Arrhenius plots) was increased by ∼45%. Foot muscle Na + /K + -ATPase from estivated snails also showed an 80% increase in K m Na + and a 60% increase in K a Mg 2+ as compared with active snails, whereas hepatopancreas Na + /K + -ATPase showed a 70% increase in I 50 K + during Estivation. Western blotting with antibodies recognizing the alpha subunit of Na + /K + -ATPase showed no change in the amount of enzyme protein during Estivation. Instead, the Estivation-responsive change in Na + /K + -ATPase activity was linked to posttranslational modification. In vitro incubations manipulating endogenous kinase and phosphatase activities indicated that Na + /K + -ATPase from estivating snails was a high phosphate, low activity form, whereas dephosphorylation returned the enzyme to a high activity state characteristic of active snails. Treatment with protein kinases A, C or G could all mediate changes in enzyme properties in vitro that mimicked the effect of Estivation, whereas treatments with protein phosphatase 1 or 2A had the opposite effect. Reversible phosphorylation control of Na + /K + -ATPase can provide the means of coordinating ATP use by this ion pump with the rates of ATP generation by catabolic pathways in estivating snails.