The Experts below are selected from a list of 7476 Experts worldwide ranked by ideXlab platform
Herve Prats - One of the best experts on this subject based on the ideXlab platform.
-
control of the vascular endothelial growth factor internal ribosome entry site ires activity and translation initiation by alternatively spliced coding sequences
Journal of Biological Chemistry, 2004Co-Authors: Stephanie Bornes, Mathieu Boulard, Corinne Hieblot, Catherine Zanibellato, Jason S Iacovoni, Herve Prats, Christian TouriolAbstract:Abstract The vascular endothelial growth factor-A (VEGF) gene locus contains eight exons that span 14 kb. Alternative splicing generates multiple, different mRNAs that in turn translate into at least five protein isoforms. While the canonical AUG start codon is located at position 1039 in exon 1, there also exists an upstream, in-frame CUG initiation codon that drives expression of L-VEGF, containing an additional 180 amino acids. Two separate internal ribosome entry sites (IRES) regulate the activity of each initiation codon. Thus the 5′-UTR of VEGF, which comprises the majority of exon 1, consists of IRES B, the CUG, IRES A, and the AUG, from 5′ to 3′. Previously, it has been shown that IRES B regulates initiation at the CUG and IRES A regulates AUG usage. In this study, we have found evidence that the exon content of the VEGF mRNA, determined through alternative splicing, controls IRES A activity. While the CUG is most efficient at initiating translation, transcripts that lack both exons 6 and 7 and therefore contain an exon 5/8 junction lack AUG-initiated translation. The process of splicing is not responsible for this start codon selection since transfection of genomic and cDNA VEGF sequences give the same expression pattern. We hypothesize that long range tertiary interactions in the VEGF mRNA regulate IRES activity and thus control start codon selection. This is the first report describing the influence of alternatively spliced coding sequences on codon selection by modulating IRES activity.
-
new vascular endothelial growth factor isoform generated by internal ribosome entry site driven cug translation initiation
Molecular Endocrinology, 2001Co-Authors: Isabelle Huez, Stephanie Bornes, Damien Bresson, Laurent Creancier, Herve PratsAbstract:We recently demonstrated that the very long 5′-untranslated region (5′-UTR) of the vascular endothelial growth factor (VEGF) mRNA contains two independent internal ribosome entry sites (IRES A and B). In the human sequence, four potential CUG translation initiation codons are located in between these IRES and are in frame with the classical AUG start codon. By in vitro translation and COS-7 cell transfections, we demonstrate that a high mol wt VEGF isoform [called large VEGF (L-VEGF)] is generated by an alternative translation initiation process, which occurs at the first of these CUG codons. Using a bicistronic strategy, we show that the upstream IRES B controls the translation initiation of L-VEGF. This isoform is 206 amino acids longer than the classical AUG-initiated form. With a specific antibody raised against this NH2 extension, we show that the L-VEGF is present in different mouse tissues or in transfected COS-7 cells. We also demonstrate that L-VEGF is cleaved into two fragments: a 23-kDa NH2-spe...
-
alternative translation of human fibroblast growth factor 2 mrna occurs by internal entry of ribosomes
Molecular and Cellular Biology, 1995Co-Authors: Stephan Vagner, Herve Prats, Marieclaire Gensac, Arlette Maret, F Bayard, F Amalric, Annecatherine PratsAbstract:Alternative initiations of translation of the humanfibroblast growth factor 2 (FGF-2) mRNA, at three CUG start codons and one AUG start codon, result in the synthesis of four isoforms of FGF-2. This process has important consequences on the fate of FGF-2: the CUG-initiated products are nuclear and their constitutive expression is able to induce cell immortalization, whereas the AUG-initiated product, mostly cytoplasmic, can generate cell transformation. Thus, the different isoforms probably have distinct targets in the cell. We show here that translation initiation of the FGF-2 mRNA breaks the rule of the cap-dependent ribosome scanning mechanism. First, translation of the FGF-2 mRNA was shown to be cap independent in vitro. This capindependent translation required a sequence located between nucleotides (nt) 192 and 256 from the 5*end of the 318-nt-long 5*untranslated region. Second, expression of bicistronic vectors in COS-7 cells indicated that the FGF-2 mRNA is translated through a process of internal ribosome entry mediated by the mRNA leader sequence. By introducing additional AUG codons into the RNA leader sequence, we localized an internal ribosome entry site to between nt 154 and 318 of the 5*untranslated region, just upstream of thefirst CUG. The presence of an internal ribosome entry site in the FGF-2 mRNA suggests that the process of internal translation initiation, by controlling the expression of a growth factor, could have a crucial role in the control of cell proliferation and differentiation.
Vilas M. Salokhe - One of the best experts on this subject based on the ideXlab platform.
-
Improvement of a power tiller cage wheel for use in swampy peat soils
Journal of Terramechanics, 2002Co-Authors: A Hendriadi, Vilas M. SalokheAbstract:Abstract This study was aimed at investigating traction performance of a cage wheel for use in swampy peat soils in Indonesia. The tests were conducted in a soil bin filled with peat soil taken from the swampy areas. A set up was developed to measure tractive performance of a single cage wheel. Deep sinkage and high wheel slip were identified as the major problems of using the existing cage wheel design in swampy peat soils. The results revealed that increasing the Lug angle from 15 to 35° and the length of Lug improved the tractive performance of the cage wheel significantly, while increasing the number of Lugs from 14 to 18 and width of Lug did not improve the tractive performance significantly. A cage wheel with Lug size 325×80 mm, 35° Lug angle, 14 Lugs (26° Lug spacing), with 2 circumferential flat rings installed on the inner side of the Lugs, out performed the other settings for use with power tillers in swampy peat soils.
-
Pull, lift and side force characteristics of cage wheels with opposing circumferential Lugs
Soil & Tillage Research, 2001Co-Authors: C. Watyotha, Vilas M. SalokheAbstract:Abstract This study was aimed at finding the effect of a Lug parameter that has been considered less important in improving the performance of cage wheels. This was the Lug arrangement or configuration like a rubber tire on the cage wheels, called opposing circumferential Lugs. The experiments were carried out in a laboratory soil bin with clay soil of 49% average soil moisture content and 135 kN average cone index. Cage wheels with opposing circumferential Lugs at four levels of circumferential angle, 0°, 15°, 30° and 45°, were evaluated and their performance compared with normal cage wheels. The Lug spacing and wheel slip of the test wheels were varied from 20°, 24°, 30° to 40° and from 25, 40 to 55%, respectively. All tests were conducted at a constant Lug sinkage of 7 cm and at 20 rpm rotational speed of the wheel. The characteristics of three orthogonal force components produced by the cage wheels with opposing circumferential Lugs were obtained by using a triaxial dynamometer. The pull and lift forces of the opposing Lugs at circumferential angles of 15° and 30° were significantly higher than those of the normal Lugs due to increase in the shear area in the corresponding direction, caused by the increase in Lug length at larger circumferential angle. However, the wheel forces were drastically affected by the influence of the opposing circumferential Lug interference at 45° circumferential angle. The better balancing of side forces could be obtained by increasing the circumferential angle and decreasing the Lug spacing. The cage wheels with opposing circumferential Lugs at 15° circumferential angle, 24° and 30° Lug spacing gave superior performances as compared to other combinations.
-
PM—Power and Machinery: Tractive Performance of Cage Wheels with Opposing Circumferential Lugs
Journal of Agricultural Engineering Research, 2001Co-Authors: C. Watyotha, Vilas M. SalokheAbstract:Abstract Experiments were conducted in a laboratory soil bin with clayey soil to determine the tractive performance of cage wheels as affected by opposing circumferential Lugs, Lug spacing and wheel slip. Also, the performance was compared with conventional or normal cage wheels. The power of the modified wheels reached a peak at about 30–40% wheel slip depending on the circumferential angle and Lug spacing. The modified wheels with 15° circumferential angle at 24 and 30° Lug spacings showed significantly higher tractive power compared to other combinations. Although the power of the modified wheels was higher than that of the conventional wheels, the traction efficiencies between the modified and normal wheels were not significantly different. The average wheel slip at the peak tractive efficiency was about 34% for all circumferential angles and Lug spacings. Based on the performance and cost of materials, the cage wheel with opposing circumferential angled Lugs at 15° circumferential angle and 30° Lug spacing is recommended for the design of power tillers in Thailand.
-
Effect of circumferential angle, Lug spacing and slip on Lug wheel forces
Journal of Terramechanics, 2001Co-Authors: C. Watyotha, D. Gee-clough, Vilas M. SalokheAbstract:Abstract This study was conducted to investigate the effect of circumferential angle, Lug spacing and wheel slip on forces produced by a cage wheel. Experiments were conducted in a laboratory soil bin having Bangkok Clay soil with 51% (d.b.) soil moisture content. Six ring-type loadcells were used to measure the soil horizontal, vertical and transverse reactions on the cage wheel Lugs. The circumferential angle was varied from 0, 15, 30 to 45°. The Lug spacing and wheel slip were varied from 20, 30 to 40° and 20, 35 to 50% respectively. All the force measurements were done at a constant 7 cm sinkage. The results showed that increasing circumferntial angle up to 45° can reduce variation in Lug wheel forces, at the same time it had little effect on the mean pull and lift values. The side force was affected by the changes of circumferential angle. The 20° Lug spacing not only gave the minimum variations but also maximum mean Lug forces. The highest Lug wheel forces occurred at 35% wheel slip.
-
Effects of low-to-medium slip, Lug spacing and moisture content on Lug forces
Journal of Terramechanics, 1994Co-Authors: Vilas M. Salokhe, Tran Thi Hong, D. Gee-cloughAbstract:Abstract The effects of low-to-medium slip, Lug spacing and moisture content on Lug forces in clay soil were investigated in a laboratory soil bin with the help of two model Lugs. Perpendicular and radial soil reactions on the Lug were measured and they were converted to Lug pull and lift forces. The Lug slip was varied from 5 to 10, 15, 20 and 25%. The measurements were conducted in clay soils with 6.3, 27.4 and 51% soil moisture contents. The Lug spacing was varied from 20° to 30° and 40°. The perpendicular, pull and lift forces increased after Lug entry into the soil and, after attaining a certain peak value, they decreased and reached a zero value at Lug exit. The increase in Lug slip from 5 to 25% caused an increase in Lug forces on both Lugs. The increase in the soil moisture content from 6.3 to 27.6% caused increase in Lug forces on both Lugs, but further increase in moisture content to 51% decreased the Lug forces. Lug spacing showed a significant effect on Lug forces produced by the succeeding Lug. The increase in Lug slip increased the Lug forces at any given Lug spacing and moisture content.
Wawan Hermawan - One of the best experts on this subject based on the ideXlab platform.
-
Analisis Performansi Model Roda Ramping Bersirip (Narrow Lug Wheel) pada Tanah Basah di Soil bin
Bogor Agricultural University, 2018Co-Authors: Muhammad Idkham, Wawan Hermawan, Tineke Mandang, Gatot PramuhadiAbstract:The design of Lug wheels are generally used for cultivation only, not for seeding, planting and weeding. This is due not compatible the shape and size of the Lug wheel general design (existing). Therefore it would need to develop a design of narrow Lug wheel which shape and size suitable for rice cultivation on the activities of seeding, planting and weeding. The purpose of this study is to analysis the performance of narrow Lug wheel for wetland at soil bin test. Lug angle and Lug height were were varied, designed Lug angle of 300, 400 and 450, with with Lug width 7 cm and Lug heights 7 cm , 10.5 cm and 14 cm. Research result analysis included relation of tractive efficiency, wheel slip, wheel sinkage to several levels of drawbar load, and several levels of Lug angle and Lug height ratio. Lug angle have a dominant influence on the change of slip, sinkage and tractive efficiency. The optimal Lug dimension and Lug angle is was was resulted by wide of Lug was was 7 cm, high was was 10,5cm and and angle of of 45 degrees, maximum tractive efficiency value on optimal Lug dimension and Lug angle was was 24.5%
-
Tractive Performance Testing of Lug Wheel in a Soil Bin
2014Co-Authors: Taufik Rizaldi, Wawan Hermawan, Tineke Mandang, Setyo PertiwiAbstract:Tractive performance testing of Lug wheel was carried out at Siswadhi Soepardjo Field Laboratory, Department of Mechanical Engineering and Bio-systems, Leuwikopo IPB, Bogor. Tested Lug wheel with 42 cm in diameter and varying numbers of Lug which were 8, 10, and 12 Lugs, respectively. Lug angle was varied from 30°, 35°, and 40°. Lug length and width was 15 and 8 cm, respectively. Wheel rotation was 1013 rps. The results showed that the smallest wheel torque was obtained when a 12 Lug-wheel was used with Lug angle 30°, while the highest was at 12 Lug wheels and Lug angle at 40°. The smallest tractive efficiency, about 21.91%, was obtained when a 10 Lug-wheel was used with Lug angle 40°. The highest efficiency was obtained when the Lug wheel has 12 Lugs with Lug angle 30°, which was about 34.62%. The higher tractive efficiency, the better tractive performance would be achieved.
-
Theoretical analysis of soil reaction on a Lug of the movable Lug cage wheel
Journal of Terramechanics, 2000Co-Authors: Wawan Hermawan, Minoru Yamazaki, Akira OidaAbstract:Abstract The measurement of soil reaction forces on a Lug of a movable Lug cage wheel was carried out in a soil bin. To elucidate the experimental results, a theoretical analysis of soil reaction forces on the Lug of the movable Lug cage wheel was made by using an analysis of the Lug trajectory and a modified theory in soil–vehicle mechanics. The existing theory was modified and adjusted by considering the actual Lug trajectory and the soil trench made by the preceding Lug. The results showed that the theoretical analysis gave a good representation of the reaction forces measured experimentally. The higher pull and lift forces of the movable Lug cage wheel compared with those of the fixed Lug wheel was supported by the theoretical analysis. Although the theoretical representation of soil reaction forces should be improved by further works, it is sufficiently accurate to estimate the performance of the movable Lug cage wheels by the proposed theory.
-
Design and traction performance of the movable Lug wheel
Journal of Terramechanics, 1998Co-Authors: Wawan Hermawan, Minoru Yamazaki, Akira OidaAbstract:A movable Lug wheel using a rollers-sliding groove mechanism was designed, constructed and tested. Two types of Lug moving patterns of the movable Lug wheel were proposed and evaluated. Tests were conducted in a soil bin test apparatus to determine the traction performance of the wheel as affected by Lug moving pattern, Lug spacing, horizontal load and vertical load. Similar tests were also conducted using a fixed Lug wheel. Generally, under the same level of vertical load, the fixed Lug wheel sank more than the movable Lug wheels did. However in general, under various horizontal loads, there was no significant difference of slip between the movable Lug wheel and the fixed Lug wheel. Among the test Lug wheels, the movable Lug wheel with Lug moving pattern-2 required the smallest driving torque and developed the highest traction efficiency.
-
Experimental analysis of soil reaction on a Lug of a movable Lug wheel
Journal of Terramechanics, 1998Co-Authors: Wawan Hermawan, Minoru Yamazaki, Akira OidaAbstract:Abstract A movable Lug wheel was tested in a soil bin test apparatus to determine its traction performance and to measure the soil reaction forces on its Lugs. Similar tests were also conducted using a fixed Lug wheel. The effects of the Lug motion pattern, Lug spacing and horizontal load on pull and lift forces were studied. From the experiments it is confirmed that the movable action of the Lug plate could generate superior pull and lift forces in comparison with the fixed Lug wheel. Among the test wheels, Lug motion pattern-2 generated the highest pull and lift forces. Within the range of the test conditions, there was no significant difference in pull and lift forces of the Lug plate between the test Lug wheels with 12 Lugs and 15 Lugs at the same level of horizontal and vertical loads. The increase of horizontal load up to 200 N generally increased the pull force and generated smaller rolling resistance before the Lug left the soil, but did not increase the lift force significantly. The patterns of pull force, lift force and drawbar pull generated under a constant slip were slightly different from those under a constant horizontal load. Finally, the results were also elucidated by their actual Lug trajectories in soil.
Stephanie Bornes - One of the best experts on this subject based on the ideXlab platform.
-
control of the vascular endothelial growth factor internal ribosome entry site ires activity and translation initiation by alternatively spliced coding sequences
Journal of Biological Chemistry, 2004Co-Authors: Stephanie Bornes, Mathieu Boulard, Corinne Hieblot, Catherine Zanibellato, Jason S Iacovoni, Herve Prats, Christian TouriolAbstract:Abstract The vascular endothelial growth factor-A (VEGF) gene locus contains eight exons that span 14 kb. Alternative splicing generates multiple, different mRNAs that in turn translate into at least five protein isoforms. While the canonical AUG start codon is located at position 1039 in exon 1, there also exists an upstream, in-frame CUG initiation codon that drives expression of L-VEGF, containing an additional 180 amino acids. Two separate internal ribosome entry sites (IRES) regulate the activity of each initiation codon. Thus the 5′-UTR of VEGF, which comprises the majority of exon 1, consists of IRES B, the CUG, IRES A, and the AUG, from 5′ to 3′. Previously, it has been shown that IRES B regulates initiation at the CUG and IRES A regulates AUG usage. In this study, we have found evidence that the exon content of the VEGF mRNA, determined through alternative splicing, controls IRES A activity. While the CUG is most efficient at initiating translation, transcripts that lack both exons 6 and 7 and therefore contain an exon 5/8 junction lack AUG-initiated translation. The process of splicing is not responsible for this start codon selection since transfection of genomic and cDNA VEGF sequences give the same expression pattern. We hypothesize that long range tertiary interactions in the VEGF mRNA regulate IRES activity and thus control start codon selection. This is the first report describing the influence of alternatively spliced coding sequences on codon selection by modulating IRES activity.
-
new vascular endothelial growth factor isoform generated by internal ribosome entry site driven cug translation initiation
Molecular Endocrinology, 2001Co-Authors: Isabelle Huez, Stephanie Bornes, Damien Bresson, Laurent Creancier, Herve PratsAbstract:We recently demonstrated that the very long 5′-untranslated region (5′-UTR) of the vascular endothelial growth factor (VEGF) mRNA contains two independent internal ribosome entry sites (IRES A and B). In the human sequence, four potential CUG translation initiation codons are located in between these IRES and are in frame with the classical AUG start codon. By in vitro translation and COS-7 cell transfections, we demonstrate that a high mol wt VEGF isoform [called large VEGF (L-VEGF)] is generated by an alternative translation initiation process, which occurs at the first of these CUG codons. Using a bicistronic strategy, we show that the upstream IRES B controls the translation initiation of L-VEGF. This isoform is 206 amino acids longer than the classical AUG-initiated form. With a specific antibody raised against this NH2 extension, we show that the L-VEGF is present in different mouse tissues or in transfected COS-7 cells. We also demonstrate that L-VEGF is cleaved into two fragments: a 23-kDa NH2-spe...
Akira Oida - One of the best experts on this subject based on the ideXlab platform.
-
Theoretical analysis of soil reaction on a Lug of the movable Lug cage wheel
Journal of Terramechanics, 2000Co-Authors: Wawan Hermawan, Minoru Yamazaki, Akira OidaAbstract:Abstract The measurement of soil reaction forces on a Lug of a movable Lug cage wheel was carried out in a soil bin. To elucidate the experimental results, a theoretical analysis of soil reaction forces on the Lug of the movable Lug cage wheel was made by using an analysis of the Lug trajectory and a modified theory in soil–vehicle mechanics. The existing theory was modified and adjusted by considering the actual Lug trajectory and the soil trench made by the preceding Lug. The results showed that the theoretical analysis gave a good representation of the reaction forces measured experimentally. The higher pull and lift forces of the movable Lug cage wheel compared with those of the fixed Lug wheel was supported by the theoretical analysis. Although the theoretical representation of soil reaction forces should be improved by further works, it is sufficiently accurate to estimate the performance of the movable Lug cage wheels by the proposed theory.
-
Design and traction performance of the movable Lug wheel
Journal of Terramechanics, 1998Co-Authors: Wawan Hermawan, Minoru Yamazaki, Akira OidaAbstract:A movable Lug wheel using a rollers-sliding groove mechanism was designed, constructed and tested. Two types of Lug moving patterns of the movable Lug wheel were proposed and evaluated. Tests were conducted in a soil bin test apparatus to determine the traction performance of the wheel as affected by Lug moving pattern, Lug spacing, horizontal load and vertical load. Similar tests were also conducted using a fixed Lug wheel. Generally, under the same level of vertical load, the fixed Lug wheel sank more than the movable Lug wheels did. However in general, under various horizontal loads, there was no significant difference of slip between the movable Lug wheel and the fixed Lug wheel. Among the test Lug wheels, the movable Lug wheel with Lug moving pattern-2 required the smallest driving torque and developed the highest traction efficiency.
-
Experimental analysis of soil reaction on a Lug of a movable Lug wheel
Journal of Terramechanics, 1998Co-Authors: Wawan Hermawan, Minoru Yamazaki, Akira OidaAbstract:Abstract A movable Lug wheel was tested in a soil bin test apparatus to determine its traction performance and to measure the soil reaction forces on its Lugs. Similar tests were also conducted using a fixed Lug wheel. The effects of the Lug motion pattern, Lug spacing and horizontal load on pull and lift forces were studied. From the experiments it is confirmed that the movable action of the Lug plate could generate superior pull and lift forces in comparison with the fixed Lug wheel. Among the test wheels, Lug motion pattern-2 generated the highest pull and lift forces. Within the range of the test conditions, there was no significant difference in pull and lift forces of the Lug plate between the test Lug wheels with 12 Lugs and 15 Lugs at the same level of horizontal and vertical loads. The increase of horizontal load up to 200 N generally increased the pull force and generated smaller rolling resistance before the Lug left the soil, but did not increase the lift force significantly. The patterns of pull force, lift force and drawbar pull generated under a constant slip were slightly different from those under a constant horizontal load. Finally, the results were also elucidated by their actual Lug trajectories in soil.
-
The characteristics of soil reaction forces on a single movable Lug
Journal of Terramechanics, 1997Co-Authors: Wawan Hermawan, Akira Oida, Minoru YamazakiAbstract:In order to understand clearly the characteristics of the soil reaction forces on a single movable Lug, the resultant of measured soil reaction forces was determined and presented along with its position on the Lug plate. The resultant of soil reaction forces acting on the movable Lug increased gradually and reached the maximum value when the Lug was on about its lowest position in the soil, then it decreased without offering any downward resistance to the Lug till the Lug left the soil. The maximum resultant force of the movable Lug was higher than that of a fixed Lug. The point of action of the resultant force on the movable Lug shifted in a similar way in all test cases, that is, it moves to the center of the Lug from the outer tip until it reaches the position where it becomes the maximum, then it moves to the outer tip till the Lug leaves the soil. The inclination angle of the resultant force increased with the decrease of Lug inclination angle. The bigger Lug sinkage of the movable Lug produced bigger soil reaction forces and shifted the point of action of the resultant force from the tip part to the central part of the Lug. However, there was no significant effect of the Lug sinkage on the direction of the resultant force. The increase in Lug slippage from 25% to 50% brought bigger soil reaction forces on the movable Lug, but did not influence the direction and point of action of the resultant force.
-
Measurement of soil reaction forces on a single movable Lug
Journal of Terramechanics, 1996Co-Authors: Wawan Hermawan, Akira Oida, Minoru YamazakiAbstract:Abstract In order to clarify characteristics of a new mechanism called a movable Lug, a model of a single movable Lug equipped with an L-shaped force transducer has been developed. The soil reaction forces (normal and tangential) on a flat single movable Lug, a curved single movable Lug and a fixed Lug were measured on wet sandy loam soil in the laboratory soil bin test. These measured forces then were converted to Lug pull and lift forces. The pull and lift forces obtained by the flat movable Lug with 45° Lug inclination angle and the curved movable Lug were higher than those of the fixed Lug. It was observed that the lift force of the fixed Lug achieved its peak and dropped earlier than those of the movable Lugs. However, the peaks of pull and lift forces of the flat and curved movable Lugs were almost the same. The flat movable Lug with 45° Lug inclination angle generated a slightly higher peak of pull force than those with 30° and 60° Lug inclination angles. However, the higher Lug inclination angle produced, the lower peak of lift force. It was observed that the pull and lift forces increased as the sinkage increased. In contrast to the flat movable Lug with 45° Lug inclination angle, the curved movable Lug produced greater lift force especially at high sinkage. The increase in Lug slip from 5% to 25 and 50% caused an increase in the peaks of pull and lift forces. The soil moisture content affected the Lug forces significantly.
