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Fine Mapping of Pa-6 Gene for Purple Apiculus in Rice
Xu Liu,Xu Sun,Wenying Wang,Hanfeng Ding,Wei Liu,Guangxian Li,Mingsong Jiang,Changxiang Zhu,Fangyin Yao 한국식물학회 2012 Journal of Plant Biology Vol.55 No.3
Purple apiculus is one of the important agronomic traits of rice. Single-segment substitution line (SSSL) W23-07-6-02-14 in the genetic background of an elite rice variety Huajingxian74 (HJX74) with the substituted interval of RM225-RM217-RM253 on the chromosome 6 was found to have purple apiculus (Pa). To map the gene governing Pa,W23-07-6-02-14 was crossed with the recipient HJX74 to develop an F2 secondary segregation population. The ratio of purple apiculus to green apiculus showed a good fit to 3:1 ratio,indicating that Pa was controlled by a major dominant gene. The gene locus for Pa was tentatively designated as Pa-6. Using 430 individuals from the F2 segregation population, the Pa-6 locus was mapped between two SSR markers RM19556and RM19561 with genetic distances of 0.2 and 0.3 cM,respectively. For fine mapping of the Pa-6 gene, a large F2:3segregation population of 3890 individuals was developed from F2 heterzygous plants in the RM19556-RM19561 region. Recombinant analyses further mapped the Pa-6 gene locus to an interval of 41.7-kb bounded L02 and RM19561. Sequence analysis of this 41.7-kb region revealed that it contains eleven open reading frames (ORFs), of which, ORF5 is classified as the one that is associated with the C (chromogen for anthocyanin) gene, it was presumed to be the candidate gene for Pa. This result provided a foundation of map-based cloning and function analysis of the Pa-6 gene.
Improvement of Positioning Error on a Ball Screw by Cooling System
Xu, Zhe Zhu,Zhang, Qi,Lyu, Sung Ki Trans Tech Publications, Ltd. 2011 Applied Mechanics and Materials Vol.86 No.-
<P>A high speed ball screw system generates more heat naturally and resultant more thermal expansion, which adversely affects the accuracy of positioning. Therefore, an air cooling system was set in ball screw shaft in this paper to dominate the thermal error and achieve temperature equilibrium faster. In order to estimate the thermal error of ball screw system and effectiveness of air cooling system, thermal behavior models of finite element method and modified lumped capacitance method were developed separately which includes the heat generation power of the main heat source of the ball screw system and other boundary conditions. The completed models were used to simulate the temperature distribution, thermal deformation and air cooling performance. Compared with experiments, it is shown that these methods can well predict the air cooling performance.</P>
Association Between the Ku70-1310C/G Promoter Polymorphism and Cancer Risk: a Meta-analysis
Xu, Lu,Ju, Xiao-Bing,Li, Pu,Wang, Jue,Shi, Zhu-Mei,Zheng, Ming-Jie,Xue, Dan-Dan,Xu, Yan-Jie,Yin, Yong-Mei,Wang, Shui,You, Yong-Ping Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.2
Ku70 plays an important role in DNA double-strand break repair. Studies revealing conflicting results on the role of the Ku70-1310C/G promoter polymorphism on cancer risk led us to perform a meta-analysis to investigate this relationship. Ten case-control studies with 2566 cases and 3058 controls were identified. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of associations. The overall results suggested no association between the Ku70-1310C/G promoter polymorphism and total cancer risk. However, on stratified analysis, significantly increased risks were observed among the Asian population (GG vs. CC: OR=1.50, 95%CI=1.10-2.06; GG vs. CC/CG: OR=1.47, 95%CI=1.07-2.01) and population-based case-control studies (GG vs. CC: OR=1.57, 95%CI=1.12-2.22; CG vs. CC: OR=1.35, 95%CI=1.11-1.64; CG/GG vs. CC: OR=1.37, 95%CI=1.14-1.65). Additionally, variant genotypes were associated with a significantly increased breast cancer risk (GG vs. CC: OR=1.80, 95%CI=1.26-2.56; GG vs. CC/CG: OR=1.40, 95%CI=1.01-1.95).
Xu Zhu,Lin Wang,Yingyan Han,Chaojie Liu,Shuangxi Fan 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.4
The alleviation eff ects of exogenous putrescine treatment on the ultrastructure of and calcium ion fl ow rate in lettuce ( Lactucasativa L.) leaf cells under drought stress were studied. Lettuce seedlings were treated with foliar sprays of 0.1 mM putrescinefor 8 days, after which drought stress was simulated by using 10% polyethylene glycol 6000. The morphological characteristicsof the seedlings and the calcium ion fl ow rate across stomatal guard cells were subsequently determined, and the leaf cellultrastructure was observed via transmission electron microscopy. Under drought stress, the morphological characteristics of the seedlings decreased, and calcium ion infl ux was predominant in the guard cells. In addition, compared to that under control conditions, the stomatal density under drought stress conditions increased signifi cantly, the open/closed stoma ratio was lower, and the degree of stomatal opening was smaller. Exogenous putrescine sprays eff ectively reduced the stomatal density, increased the degree of stomatal opening, and increased the proportion of open stomata. In addition, the chloroplasts became round in shape, the thylakoid structure became blurry in appearance, the number of starch grains decreased, many osmium granules were produced, and plasmolysis occurred in the mesophyll cells. However, the chloroplasts were elongated, the thylakoid structure was clear, the starch grains were abundant, few osmium granules were produced, and plasmolysis did not occur. The above results show that, by altering the leaf cell ultrastructure as well as the fl ow rate and direction of calcium ions in guard cells, exogenous putrescine eff ectively improves the drought tolerance of lettuce.
Xu Zhu,Rui Yang,Yingyan Han,Jinghong Hao,Chaojie Liu,Shuangxi Fan 한국원예학회 2020 Horticulture, Environment, and Biotechnology Vol.61 No.3
Nitrate nitrogen (NO 3− ) and ammonium N (NH 4+ ) are the two main forms of nitrogen (N). The eff ects of the NO 3− :NH 4+ ratio(0:100, 25:75, 50:50, 75:25, and 100:0) in the nutrient solution on growth, pigment content, photosynthetic parameters, chlorophyll(Chl) precursor content, and chloroplast mitochondrial ultrastructure of lettuce leaves were evaluated to determine theappropriate N ratio for the growth of lettuce. The results showed that a ratio of nitrate to ammonium of 75:25 compared withthe single N form resulted in signifi cantly higher fresh weights in the shoots and the lower parts of the lettuce. The growthrate, as indicated by the CO 2 response curve, was increased because of the carboxylation effi ciency and dark respiration rate(Rday) of the lettuce seedlings, and the diff erence between the light compensation point and CO 2 compensation point wasreduced under single nitrate N treatment. The contents of δ-aminolevulinic acid (ALA), porphobilinogen, uroporphyrinogenIII, protoporphyrin IX, and Mg-protoporphyrin IX in seedlings at 75:25 nitrate:ammonium were higher than those inseedlings under the other treatments. The contents of Chl a and b were also the highest when the ratio of nitrate ammoniumwas 75:25. The chloroplast structure of lettuce leaves was intact, the cell membrane was completely closed to the cell wall,and the organelles were closely arranged on the cell membrane. The chloroplast was spindle-shaped and full of vesicles. The whole mitochondria were rich, the base particles were rich, the base granules were clear and rich, and the mitochondriaexhibited the overall best state with a complete structure, rich sputum, and dense inclusions. The above results show that thenutrient solution with a ratio of nitrate to ammonium of 75:25 was more conducive to Chl synthesis and the promotion ofphotosynthesis and root growth in lettuce seedlings than the other treatments. The single nitrate N nutrient solution reducedChl synthesis and photosynthesis in lettuce seedlings, while the single ammonium N nutrient solution aff ected the growthof lettuce seedlings, resulting in lower growth of lettuce shoots and roots. Therefore, the nutrient solution ratio of nitrate toammonium of 75:25 is the most suitable for the lettuce seedling growth.
A Study on Improvement of Ball Screw System Positioning Error with Liquid-Cooling
Xu, Zhe-Zhu,Liu, Xiao-Jing,Choi, Chong-Hun,Lyu, Sung-Ki 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.12
The demand for higher productivity and tight part tolerances requires machine tools to have faster and more accurate feed drive systems. As tried and tested technology, ball screw drive systems are still used in a majority of machine tools due to their low cost and high degree of stiffness. A high-speed ball screw drive system generates more heat and results in greater positioning error, adversely affecting the accuracy of machined parts. In this paper, we discuss the placement of a liquid-cooling system using water, coolant oil, light oil and cutting oil as coolants in a ball screw shaft to avoid thermal errors and achieve temperature equilibrium faster. In order to estimate the positioning error and thermal distribution of the ball system and effectiveness of the liquid-cooling system, all possible heat gain-loss sources were analyzed and considered calculation factors. The following paper also presents degree of positioning error improvement when a circulation liquid-cooling system and forced liquid-cooling system were employed. When comparing the predictions and the experimental results, we can see very significant cooling performance and a high degree of consistency between prediction and reality.