Min Peng

Distribution of Stipa purpurea steppe in the Northeastern Qinghai-Xizang Plateau (China)

The aims of this study were to examine the spatial distribution pattern of Stipa purpurea steppe and to elucidate their possible correlation with environmental factors, by means of multivariate quantitative analysis. Two data sets were subjected to the Two-way Indicator Species Analysis (TWINSPAN), the community similarity analysis and the Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA). The distribution pattern of Stipa purpurea steppe showed obvious geographical heterogeneity in different regions and some homogeneity in the same region. And the altitude, longitude and latitude were the three major environmental factors affecting Stipa purpurea steppe’s distribution.

Culturable actinomycetes from desert ecosystem in northeast of Qinghai-Tibet Plateau

In this study, 53 actinomycetes strains were isolated from desert ecosystems located in northeast of Qinghai-Tibet Plateau and grouped into four RFLP patterns. Twenty-six actinomycetes with obvious morphology differences were chosen for phylogenetic diversity study and antimicrobial testing. As a result, the 16S rRNA gene sequencing showed that these strains belonged to Streptomyces, Micromonospora, Saccharothrix, Streptosporangium and Cellulomonas, and that most of the strains had antimicrobial bioactivity. The PKS and NRPS genes detection indicated diversified potential bioactive products of actinomycetes in this ecosystem. Among these strains, Sd-31 was chosen to study the bioactive products using HPLC-MS because of its optimum antimicrobial bioactivity. The result showed that it might produce Granatomycin A, Granatomycin C, and an unknown compound.

GC–MS analysis of liposoluble constituents from the stems of Cynomorium songaricum

In order to evaluate the differences and similarities between the liposoluble constituents in Cynomorium songaricum populations, stem liposoluble constituents in five populations of C. songaricum collected from three different geographic regions and four different hosts were obtained by solvent extraction and analyzed by GC-MS. Cluster analysis of the percentage composition of 80 compounds showed differences in chemical composition which were related to the geographic origin rather than the host. Hexadecanoic acid was the most abundant compound in the essential oils of C. songaricum from hosts Nitraria sibirica and Nitraria tanguticum. Whereas (Z)-9-octadecenoic acid was accumulated in the oils of C. songaricum from Zygophyllum xanthoxylum and Peganum harmala. Four of the five populations had characteristic components, which were specific to each population.

Stable carbon and nitrogen isotope signatures of root-holoparasitic Cynomorium songaricum and its hosts at the Tibetan plateau and the surrounding Gobi desert in China

We first measured the δ13C and δ15N values of root holoparasite Cynomorium songaricum and its hosts from 19 sites across four provinces in northwest China, in an attempt to investigate their nutritional relationship at the Tibetan plateau and the surrounding Gobi desert. Our study showed that the δ13C of C. songaricum closely mirrored the values of its hosts, Nitraria tangutorum and N. sibirica across all sampling sites. C. songaricum was significantly depleted in 13C compared to host plants at the Tibetan plateau, showing an average parasite/host δ13C difference of−0.6 ‰. In contrast, 15N of C. songaricum was significantly enriched by+1.3 ‰ compared to the hosts, implying that these holoparasites had other nitrogen resources. Although no difference in the δ13C and δ15N values between holoparasites and hosts was detected, the δ13C and δ15N values of holoparasites were significantly correlated with those of their hosts at the Gobi desert. The δ13C versus δ15N values were significantly but negatively correlated for the hosts; however, holoparasite/host variation in δ13C was not correlated with the variation in δ15N. The δ13C versus δ15N values were negatively correlated in C. songaricum, and this relationship tended to be magnified along the increasing elevations independent of the host plants. C. songaricum at the Tibetan plateau exhibited different δ13C and δ15N signatures compared with those at the Gobi desert. Furthermore, both δ13C and δ15N values of C. songaricum and its host plants in salt marshes at the Tibetan plateau were different from those in sand sites at the Tibetan plateau and the Gobi desert. Our results indicate that the isotopic difference depends on the different altitudes and habitats and is host-specific.

Responses of reproduction and important value of dominant plant species in different plant functional type in Kobresia meadow to temperature increase

Responses of reproduction and IV (important value) of dominant plant species in different PFT to warming were studied at a Kobresia meadow in the Tibetan Autonomous State of Qinghai Province, China (37°29′–37°45′ N, 101°12′–101°33′ E, 3900 m asl) using the temperature gradient method formalized by the ITEX. Responses of Elymus nutans and Poa pratensis (Gramineous PFT) to increasing temperature were similar. The numbers of tillers, buds and IV increased in the chambers treated with higher temperature compared to the control without treatments (CK). Responses of Kobresia humilis and Carex alrofusca (Cyperaceae PFT) to increasing temperature were different, that is, the numbers of tillers and IV reached the maximum in different temperature among species, the numbers of buds decreased with the temperature increasing. The number of buds and IV of Lagotis brachystachya (Forbs PFT) decreased with the warming, but the number of stolons was initially large, and then decreased with increasing temperature. The number of buds of Ranunculus brotherusii (Forbs PFT) increased with the temperature increasing in the first year, but decreased in the second year; and IV decreased with the temperature warming. Under conditions of continued warming in the future, PFT structure will be significantly changed, Cyperaceae PFT dominant plant species original position will be replaced by Gramineae PFT dominant plant species. Cyperaceae plants will become the dominant species, and some species belonging to Forbs PFT will be eliminated from the community.

Study on Mineral Elements in Salvia roborwskii from the Qinghai-Tibet Plateau

The contents of trace elements, including aluminum, barium, beryllium, calcium, cobaltium, chromium, copper, iron, potassium, lanthanum, lithium, magnesium, manganese, sodium, nickel, phosphorus, lead, sulfur, silicon, titanium, vanadium, and zinc, were determined by ICP-AES. The mean concentrations of the 22 elements were as follows: K>Ca>Mg>Fe>Al>Na>S>P>Ba>Ti>Mn>Zn>Sr>Cu>Ni=Cr>Pb>V>Li=La>Co>Be. Principal components analysis of SPSS was applied to study the characteristic elements in Salvia roborwskii. Five principal components which accounted for 89.288% of the total variance were extracted from the original data. The first factor accounted for 56.401% of the total variance, which meant that aluminum, barium, beryllium, calcium, and cobaltium were the characteristic elements in S. roborwskii. This useful new method was used to evaluate the quality of S. roborwskii, and to provide the scientific foundation for its utilization and further research.

A critical role for very long-chain fatty acid elongases in oleic acid-mediated Saccharomyces cerevisiae cytotoxicity

Elongases FEN1/ELO2 and SUR4/ELO3 are important enzymes involved in the elongation of long-chain fatty acids (LCFAs) to very long-chain fatty acids (VLCFAs) in Saccharomyces cerevisiae. The molecular mechanism of the involvement of these elongases in lipotoxicity is unclear. In the present study, we investigated the role of VLCFA elongases in oleic acid-mediated yeast cytotoxicity. The spot test showed that yeast strains with the deletion of ELO2 or ELO3 were strikingly sensitive to oleic acid, while there was no change on the growth of strain with deleted ELO1 which was involved in the elongation of C14 fatty acid (FA) to C16 FA. By using GC-MS, the unsaturation index was increased in elo2△ and elo3△ mutants after treatment with oleic acid (OLA). However, the proportion of VLCFAs was increased in response to OLA in the wild-type strain. The growth inhibition of elo2△ and elo3△ could be partially rescued by two commonly used antioxidant agents N-acetyl cysteine (NAC) and Ascorbic acid (VC). The further study showed that exposure to excess OLA led to an increase in the levels of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS), and a decline in the quantity of reduced glutathione (GSH) in both the wild type and mutant strains. However, the antioxidant enzyme activities of superoxide dismutase (SOD) and catalase (CAT) were increased in the wild type and elo1△ strains, while they were significantly decreased in the mutants of elo2△ and elo3△ after treated with excess OLA. Thus, oxidative damage mainly contributed to the cell death induced by OLA in ole2△ and ole3△. Taken together, although disruption of ELO2 or ELO3 did not affect the cellular lipid unsaturation, they altered the distribution and propotion of cellular VLCFAs, leading to the cell membrane impairment, which augmented the ability of OLA to permeabilize the plasma membrane. The data suggest that the very long-chain fatty acids elongases ELO2 and ELO3 play important roles in lipotoxic cell death induced by OLA through maintaining a balanced FA composition in plasma membrane.

Clioquinol induces G 2 /M cell cycle arrest through the up-regulation of TDH3 in Saccharomyces cerevisiae

Clioquinol (CQ) has been used as a classical antimicrobial agent for many years. However, its mode of action is still unclear. In our study, the growth of Candida albicans and Saccharomyces cerevisiae was inhibited by CQ. It did not kill yeast cells, but shortened G1 phase and arrested cell cycle at G2/M phase. By using two-dimensional electrophoresis based proteomic approach, six proteins were found to be significantly affected by CQ. Among them, four (PDC1, ADH1, TDH3, IPP1) were up-regulated and the other two (TDH1 and PGK1) were down-regulated. According to the Saccharomyces Genome Database (SGD), these proteins were involved in various biological processes including glycolytic fermentation, gluconeogenesis, glycolytic process, amino acid catabolism, redox reaction and reactive oxygen species metabolic process. It was noted that there was a link between TDH3 and cell cycle. The overexpression of TDH3 phenocopied CQ treatment and arrested the cell cycle at G2/M phase. RT-PCR analysis showed that the mRNA levels of CLN3 and CDC28, critical genes for passage through G1 phase, were up-regulated after the treatment of CQ as well as the overexpression of TDH3. It demonstrates that CQ inhibits the growth of yeast by up-regulating the expression of TDH3 to influence the cell cycle. It is expected to provide new insights for the antimicrobial mechanism of CQ.

Chemical Composition of Three Nitraria Species Fruits

The Nitraria belongs to genus Nitraria L. of the family Zygophyllaceae. The genus has 11 species distributed in Asia, Europe, Africa and Australia. China has six species including Nitraria roborowskii Kom., Nitraria sibirica Pall., Nitraria tangutorum Bobr. etc., which are widely spread through northwest regions, mainly in Gansu, Inner Mongolia and other places [1-4]. These plants are important populations for the endangered desert vegetation which played a key role in improving the ecological environment [5,6]. The fruits of Nitraria genus (Nitrariaceae) are desert rare wild fruit, tatse sweet and sour, and their foliage is usually to feed the livestock. On the other hand, it has also been effectively used in folklore medicines to treat disease including indigestion, neurasthenia, stomach, fever and cold [7-9]. In addition, the products of Nitraria fruits have played an essential role in the local soft drink market. The fresh fruits could be eaten directly or used to produce marmalades, juices, vinegar, liquors and flavour food which are popular in the north-west of China [10-12]. Nitraria Tangutorum Bobr. grows only in China, whose fruits are rich in amino acids, vitamins and mineral elements [13-16]. Meanwhile, N. sibirica and N. roborowskii also contains various kinds of flavonoids, anthocyanins, crude proteins, sugars, etc. [17-19]. Thus, it shows the fruits of Nitraria specis are of great value for human health due to the content of flavonoids, sugar and minerals. Chemical Composition of Three Nitraria Species Fruits

The medicinal characteristics of alcohol-extraction- water-precipitation fraction from Swertia mussotii Franch.

The alcohol-extraction-water-precipitation fraction of Swertia mussotii Franch. (SME-d) had been proved to be hepatoprotective without toxicity in previous report. In this article, high performance liquid chromatography (HPLC), rat experiment and P450 model tests were employed for studying the pharmacology characteristics of SME-d. The results showed that the contents of sweroside, swertiamarin, mangiferin, gentiopicroside, and isoorientin were 0.24, 3.96, 12.30, 13.53, 16.85 mg/g in SME-d, respectively. SME-d could reduce the CCl4-induced exaltation of alanine transaminase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), total bile acid (TBA) significantly in rat, and the protective activity showed dose-dependent in 0.9 and 1.8 g/kg body weight (BW). The hepatoprotective activity of SME-d was different to positive drug bifendate, which only did on ALT value significantly. Bifendate could inhibit 66.17 ± 2.12% of CYP3A4 activity, while SME-d showed 99.0 ± 0.267% reductions on CYP1A2. The different medicinal characteristics of SME-d to bifendate, which are used widely to cure hepatitis in china, can give more choices for hepatitis. Key words: Swertia mussotii Franch, the alcohol-extraction-water-precipitation fraction, pharmacology characteristic, hepatoprotective activity.