植物纤维素合成酶基因和纤维素的生物合成

纤维素地球上最丰富的生物大分子和最重要的可再生资源,1996年克隆了第一个植物纤维素合成酶基因,植物纤维素的生物合成需要多个纤维素合成酶与其他相关酶如Korrigan纤维素酶,蔗糖合成酶等来共同完成。本文介绍了植物纤维素合成酶基因和纤维素的生物合成途径及其相关基因如蔗糖合成酶基因、KORRIG-AN基因等研究进展。     

Analysis of intracellular reducing levels in human hepatocytes on three‐dimensional focusing microchip

A novel three‐dimensional hydrodynamic focusing microfluidic device integrated with high‐throughput cell sampling and detection of intracellular contents is presented. It has a pivotal role in maintaining the reducing environment in cells. Intracellular reducing species such as vitamin C and glutathione in normal and tumor cells were labeled by a newly synthesized 2,2,6,6‐tetramethyl‐piperidine‐1‐oxyl‐based fluorescent probe. Hepatocytes are adherent cells, which are prone to attaching to the channel surface. To avoid the attachment of cells on the channel surface, a single channel microchip with three sheath‐flow channels located on both sides of and below the sampling channel was developed. Hydrostatic pressure generated by emptying the sample waste reservoir was used as driving force of fluid on the microchip. Owing to the difference between the liquid levels of the reservoirs, the labeled cells were three‐dimensional hydrodynamically focused and transported from the sample reservoir to the sample waste reservoir. Hydrostatic pressure takes advantage of its ease of generation on a microfluidic chip without any external pressure pump, which drives three sheath‐flow streams to constrain a sample flow stream into a narrow stream to avoid blockage of the sampling channel by adhered cells. The intracellular reducing levels of HepG2 cells and L02 cells were detected by home‐built laser‐induced fluorescence detector. The analysis throughput achieved in this microfluidic system was about 59–68 cells/min. Copyright © 2013 John Wiley & Sons, Ltd.     

高寒地区不同退化草地植被特性和土壤固氮菌群特性及其相关性

选取东祁连山不同退化程度的高寒草地为研究对象,调查研究其植物种类、植被盖度、高度、地上生物量等植物指标以及土壤好气性自生固氮菌和嫌气性自生固氮菌数量,在此基础上,采用real-time PCR的方法扩增nifH基因,测定不同退化程度草地土壤中固氮菌相对于土壤总细菌的量,以探讨草地退化过程中植被及土壤固氮菌群的变化规律,结果发现:随着退化程度的加深,草地植物种类逐渐减少,并且优势植物发生变化,毒杂草逐渐增多,植被的高度、盖度、地上生物量都逐渐降低。对土壤固氮菌的研究则表明,土壤好气性自生固氮菌和嫌气性自生固氮菌的数量在不同退化草地随草地退化程度的加重而减少,在同一退化程度草地土壤则是随土层深度加深而下降。对土壤固氮菌nifH基因扩增的结果也表明随着退化加剧,土壤固氮菌相对于土壤总细菌的比例在降低,进一步说明草地退化过程中土壤固氮菌不仅是数量上的下降,更是群落结构层面的变化。对植被特性和土壤固氮菌含量的相关分析表明,植被特性和土壤中固氮菌含量呈显著相关。研究从土壤固氮菌群的角度研究了草地退化的过程,说明了二者具有协同性,研究和治理草地退化必须重视土壤功能菌群尤其是固氮菌群的作用。     

Root Defense in Salicylic Acid-Altering Arabidopsis Plants in Responses to Cadmium Stress

Journal of Plant Growth Regulation - The regulatory role of salicylic acid (SA) has been extensively reported in plants subjected to cadmium (Cd) stress. However, the underlying mechanisms still...     

Metabolomics and transcriptomics provide insights into the flavonoid biosynthesis pathway in the roots of developing Aster tataricus

Journal of Plant Research - Aster tataricus (L.) is an important medicinal plant in China. Its roots are rich in flavonoids, the main medicinal components. However, the molecular basis of flavonoid...     

Pediatric Continuous Reference Intervals of Serum Insulin-like Growth Factor 1 Levels in a Healthy Chinese Children Population – Based on PRINCE Study

ObjectivesWe aimed to establish age- and sex-dependent reference intervals for insulin-like growth factor 1 (IGF-1) based on the measurements of healthy Chinese children from the pediatric reference intervals in China study and to investigate whether body mass index (BMI) and height affect IGF-1 levels.MethodsA total of 3753 individuals with eligible blood specimens resampled from the pediatric reference intervals in China population were enrolled as reference individuals. IGF-1 levels were measured using a chemiluminescent immunoassay kit. The lower limit and upper limit values of the reference individuals were calculated by defining the 2.5th and 97.5th percentiles. The skewness-median-coefficient of variation method was used to calculate the standard deviation score (SDS) of serum IGF-1, and cubic spline curves were applied to depict a smoothed curve for each age- and sex-specific stratification of the L, M, and S parameters.ResultsSerum IGF-1 levels increased with age from the age of 1 year, peaking at around the age of 13 years in girls and 15 years in boys and then began to decline (both P <.001). Before 14 years, IGF-1 levels were higher in girls than in boys at the same age, and the difference was statistically significant (P < .05), but there was no significant difference in the IGF-1 levels between girls and boys aged 14 to 16 and 18 years. The Spearman correlation coefficients of height SDS, weight SDS, and BMI SDS with IGF-1 SDS were 0.29, 0.33, and 0.20, respectively (P < .001).ConclusionThis study established age- and sex-specific normative IGF-1 data for Chinese children and adolescents between the ages of 1 and 19 years. The BMI and height SDS had no effect on IGF-1 levels in healthy children.