Analysis of chemical constituents of essential oil in purple magnolia leaves by gas chromatography-mass spectrometry

The essential oil in purple magnolia leaves was extracted by steam distillation approaches. The oil obtained was dried with anhydrous magnesium sulfate. According to the analysis of gas chromatography/mass spectrometry, more than 40 peaks were separated and 32 compounds were identified. The identified constituents represent 95% of the peak area of the essential oil. The main compounds were germacrene-D, santolina triene, caryophyllene, 1,3,7-octatriene, 3,7-dimethyl, and camphene, etc.

Ecdysteroid-responsive genes: E75 and Retinoid X Receptor (RXR), essential molt-regulating genes in the shrimp, Fenneropenaeus chinensis

本论文主要研究两种重要的调节蜕皮过程的基因—蜕皮激素效应基因E75和RXR在中国明对虾蜕皮中的作用。利用RT-PCR和RACE技术获得了编码FcE75和FcRXR的全长cDNA序列。FcRXR包含7个内含子，在对虾中存在不同的异形体，命名为RXR-1和RXR-2。应用荧光实时定量PCR分析表明FcE75和FcRXR基因在中国明对虾蜕皮前期（D3）其转录表达量明显上调。另外，FcE75和FcRXR基因在不同组织中的转录表达存在明显的差异。利用FcE75和FcRXR基因的双链RNA注射对虾能有效降低FcE75和FcRXR的表达水平。FcE75和FcRXR的体内沉默完全抑制了对虾的蜕皮过程，并且引起对虾的死亡。对不能正常蜕皮个体进行观察的结果表明，FcE75沉默的对虾，其上皮的收缩、新的刚毛及新表皮的形成均收到限制。在FcE75双链RNA沉默后的对虾中，我们检测了与蜕皮相关的一些效应因子，如chitinase等的转录，发现这些效应因子的转录明显受到抑制，说明FcE75和FcRXR在蜕皮过程中起到非常重要的作用。本论文首次阐明了这些基因在十足目甲壳动物蜕皮过程中的功能。

Geographic variation in the leaf essential oils of Juniperus sabina L. and J-sablina var. arenaria (E.H. Wilson) Farjon

The composition of the leaf oils from seven populations of J. sabina L., one population of Juniperus sabina var. arenaria (E. H. Wilson) Farjon were examined for their geographic variation. In addition, the leaf oils of J. chinensis L. and J. davurica Pall. were compared to J. sabina. Juniperus sabina var. arenarla, the sand loving juniper, oil was found to be very similar to that of J. davurica, Mongolia, and J. sabina, on sand dunes in Mongolia. This suggests that J. sabina var. arenaria might be conspecific with J. davurica. Farjon's move (2001) of J. sabina var. arenaria out of J. chinensis is supported. Considerable differentiation was found in populations of J. sabina from the Iberian peninsula. Cedrol, citronellol, safrole, trans-sabinyl acetate, terpinen-4-ol and beta-thujone were found to be polymorphic in several populations.

Effects of hypoxia on contents of essential elements in pika and rat heart

The effects of hypoxia on the levels of essential macroelements and trace elements (K, Na, Ca, Mg, Cu, Zn, Fe, and Mn) in the heart muscles of Wistar rats and plateau pikas (Ochotona curzoniae) were studied by atomic absorption spectrometry. Unlike the rat, the plateau pika is tolerant to hypoxia. The levels of K, Na, and the trace element Mn were not significantly changed in rat or pika hearts after exposure to hypoxia for 1, 10, or 25 d at simulated altitudes of 5000 and 7000 m. Other minerals (Ca, Mg, Cu, Zn, and Fe) were significantly affected by hypoxia and the levels followed different time-courses under different hypoxic regimes in these two animals. There were marked differences between the rat and pika in myocardial accumulation of essential elements such as Ca, which was increased to high levels in the rat but not affected in the pika. The results suggest that hypoxia affects animal physiological mechanisms by regulating the levels of essential elements.

Assessing the potential of VEGETATION sensor data for mapping snow and ice cover: a Normalized Difference Snow and Ice Index

The VEGETATION (VGT) sensor in SPOT 4 has four spectral bands that are equivalent to Landsat Thematic Mapper (TM) bands (blue, red, near-infrared and mid-infrared spectral bands) and provides daily images of the global land surface at a 1-km spatial resolution. We propose a new index for identifying and mapping of snow ice cover, namely the Normalized Difference Snow/Ice Index (NDSII), which uses reflectance values of red and mid-infrared spectral bands of Landsat TM and VGT. For Landsat TM data, NDSII is calculated as NDSIITM =(TM3 -TM5)/(TM3 +TM5); for VGT data, NDSII is calculated as NDSIIVGT =(B2- MIR)/(B2 + MIR). As a case study we used a Landsat TM image that covers the eastern part of the Qilian mountain range in the Qinghai-Xizang (Tibetan) plateau of China. NDSIITM gave similar estimates of the area and spatial distribution of snow/ice cover to the Normalized Difference Snow Index (NDSI=(TM2-TM5)/(TM2+TM5)) which has been proposed by Hall et al. The results indicated that the VGT sensor might have the potential for operational monitoring and mapping of snow/ice cover from regional to global scales, when using NDSIIVGT.

Comparison of comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry and gas chromatography-mass spectrometry for the analysis of tobacco essential oils

A sample of tobacco essential oil was analyzed using gas chromatography-mass spectrometry (GUMS)and comprehensive two-dimensional gas chromatography coupled to a time-of-flight mass spectrometry (GC x GC/TOFMS), respectively. In the GUMS analysis, serially coupled columns were used. By comparing the GUMS results with GC x GC/TOFMS result,,, many more components in the essential oil could be found within the two-dimensional separation space of GC x GC. The quantitative determination of components in the essential oil was performed by GC x GC with flame ionization detection (FID), using a method of multiple internal standards calibration, (c) 2005 Elsevier B.V. All rights reserved.

Quantitative determination of compounds in tobacco essential oils by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry

A quantitative analysis of the individual compounds in tobacco essential oils is performed by comprehensive two-dimensional gas chromatography (GC x GC) combined with flame ionization detector (FID). A time-of-flight mass spectrometer (TOF/MS) was coupled to GC x GC for the identification of the resolved peaks. The response of a flame ionization detector to different compound classes was calibrated using multiple internal standards. In total, 172 compounds were identified with good match and 61 compounds with high probability value were reliably quantified. For comparative purposes, the essential oil sample was also quantified by one-dimensional gas chromatography-mass spectrometry (GC/MS) with multiple internal standards method. The results showed that there was close agreement between the two analysis methods when the peak purity and match quality in one-dimensional GC/MS are high enough. (c) 2005 Elsevier B.V. All rights reserved.