Accumulation of carotenoids and expression of carotenoid biosynthesis genes in fruit flesh during fruit development in two Cucurbita maxima inbred lines

Mesocarp color is an important agronomic trait of Cucurbita maxima and is determined mainly by the contents and compositions of the carotenoids.The two inbred lines with significant differences in fruit flesh color were used in the study,the orange’312-1’and white’98-2’.Changes in seven carotenoid contents and compositions in the flesh of fruit produced by inbred lines’312-1’and’98-2’were analyzed during fruit development.The expression of eight key carotenoid biosynthesis genes in the fruit flesh were investigated during five fruit development stage in two inbred lines.As the flesh color intensified,the orange flesh color of’312-1’was determined mainly by the increased contents of lutein,β-carotene and zeaxanthin and the lack of carotenoid accumulation led to the formation of white flesh in’98-2’fruit.The expression of the LCY-e and CHYb genes was significantly stronger in’312-1’than in’98-2’,and their expression was strongly correlated with lutein andβ-carotene contents during fruit development.This study provides a deep understanding of the molecular mechanism of carotenoid biosynthesis in fruit flesh and provides a basis for additional studies on the highly refined improvement of squash quality.

Correlation of vascular endothelial growth factor to permeability of blood-brain barrier and brain edema during high-altitude exposure

BACKGROUND： Many studies have evaluated the role of vascular endothelial growth factor （VEGF） in traumatic brain edema and hemorrhagic brain edema. OBJECTIVE： To observe the effects of VEGF expression on permeability of the blood-brain barrier （BBB） during high-altitude and hypoxia exposure, and to investigate the correlation between VEGF expression and BBB permeability with regard to Evans blue staining and brain edema during high-altitude exposure. DESIGN, TIME AND SETTING： The randomized, controlled, animal study was performed at the Tanggula Etape, Central Laboratory of Chengdu Medical College, and Central Laboratory of General Hospital of Chengdu Military Area Command of Chinese PLA, China, from July 2003 to November 2004. MATERIALS： Quantitative RT-PCR kit （Sigma, USA）, VEGF ELISA kit （Biosource, USA）, and Evans blue （Jingchun, China） were acquired for this study. METHODS： A total of 180 Wistar rats were equally and randomly assigned to 15 groups： low-altitude （500 m）, middle-altitude （2 880 m）, high-altitude （4 200 m）, super-high-altitude （5 000 m）, 1,3, 5, 7, 9, 11, 13, 15, 17, 19, and 21 days of super high-altitude exposure. Wistar rats were exposed to various altitude gradients to establish a hypoxia model. MAIN OUTCOME MEASURES： Brain water content was calculated according to the wet-to-dry weight ratio. BBB permeability to Evans blue was determined by colorimetric method. VEGF mRNA and protein levels in brain tissues were detected using RT-PCR and double-antibody sandwich ELISA. RESULTS： Brain water content, BBB permeability to Evans blue, and VEGF mRNA and protein levels in brain tissues increased with increasing altitude and prolonged exposure to altitude. The greatest increase was determined on day 9 upon ascending 5 000 m. Simultaneously, VEGF expression positively correlated to BBB permeability of Evans blue and brain water content （r = 0.975, 0.917, P〈 0.01）. CONCLUSION： Increased VEGF protein and mRNA expression was responsible for increased BBB permeability, which may be an important mechanism underlying brain edema during high-altitude exposure.

A Comprehensive Study of the High Temperature Performance and Microstructure of Different High Tc Piezoelectric Ceramics

The expanding demand for piezoelectric devices working at elevated temperatures,particularly those for aerospace and automotive industries,has stimulated a great deal of research effort on high Cu-rie Temperature(T C)piezoelectric ceramics.The fabrication of this type of piezoelectric ceramics is

Effect of minor Sc addition on microstructure and stress corrosion cracking behavior of medium strength Al–Zn–Mg alloy

Influence of Sc content on microstructure and stress corrosion cracking behavior of medium strength AI-Zn-Mg alloy have been investigated by optical microscopy, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy and slow strain rate test. The results indicate that the addition of Sc results in the formation of the quaternary coherent AI3（Sc, Zr, Ti） dispersoids during homogenization treatment, which will inhibit the dynamic recrystallization behavior. The number density ofAl3（Sc, Zr, Ti） particles increases with the increase of Sc content, and thus the recrystallization fraction of hot-extruded alloy is reduced and the peak strength in two-stage artificial aging sample is enhanced. At the same time, the wide of precipitation free zone is reduced, and the content of Zn and Mg in grain boundary particles and precipitation free zone is increased with the increase of Sc content. In peak-aged state, the 0.06 wt% Sc added alloy shows the better stress corrosion cracking resistance than the Sc-free alloy because of the reduction of recrystallization fraction and the interrupted distribution of grain boundary precipitates along grain boundary. However, the further addition of Sc to 0.11 wt% will result in the deterioration of stress corrosion cracking resistance due to the increase of electrochemical activity of grain boundary particles and precipitation free zone as well as hydrogen embrittlement.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.

Phz-H2ca铁电共晶的形貌控制及其各向异性拉曼光谱

本文首次报道了Phz-H2ca铁电共晶的一种线状形貌,并通过原子力显微镜、透射电子显微镜、X射线衍射、紫外可见吸收光谱、差示扫描量热法和固体核磁等实验手段证实.共晶成核生长实验和Materials Studio软件模拟研究发现,(020)面具有最大的结合能,在较低前驱体浓度下晶核沿[010]方向组装形成动力学稳定的线状形貌,(002)面具有最小的表面能和最大生长势垒,即使在超饱和前驱体浓度下也只有(200)和(020)等晶面的生长势垒被突破,使晶核沿[100]和[010]两个方向生长为热力学稳定的六边形片状形貌.微区拉曼光谱实验研究表明,两种Phz-H2ca共晶的拉曼峰具有截然不同的各向异性响应性,归因于其不同的分子排布取向.该研究工作实现了对分子共晶的控制制备,阐明了其中的结构功能关系,为共晶功能材料的进一步大规模应用提供了有力借鉴.