人重组白蛋白基因在巴斯德毕赤酵母中的高效表达

The yeast Pichia pastoris was transformed by the multi\|copy Pichia expression vector that can express secreted human albumin.The high level expression of cell line was selected after screening.The expression of human recombinant albumin in Pichia pastoris induced by different methods were compared.The retio of secreted human albumin is 80% in total secreted proteins and the expression level reaches as high as is 10g/L.     

刺果甘草中黄酮类化合物的提取与分析

With three different methods, the total flavonoids from the roots of cultivated Gtycyrrhiza pallidiflora Maxim. were determined and compared by ultraviolet-visible spectrophotometry. The results showed that the extract yield of total flavonoids in crude extracts was 4.54% by direct determination method, 4.27% by AI（ NO3）3 colorimetry method and 2.09% by AlCl3 colorimetry method. The content of total flavonoids in roots of cultivated G. pallidiflora was only 0.05%. The cultivated G. pallidiflora in Lanzhou is not unfit for the medicine source of flavonoids.     

Exogenous abscisic acid increases stability of polysomes in embryos of triticale caryopses during germination

Some posttranslational processes that occur in embryos of germinating triticale caryopses treated with different concentrations of abscisic acid (ABA) were examined. ABA increased the ratio of cytoskeleton-bound polysomes in the total population of polysomes and depressed the share of free and membrane-bound polysomes. Using exogenous RNase, stability of the total polysomal population as well as each polysomal fraction was investigated. The total extractable polysomes isolated from embryonic tissues of germinating triticale caryopses treated with ABA were more stable than the polysomes isolated from the control sample caryopses. The contribution of the polysomes that were not digested by RNase was increased by higher concentrations of ABA applied during germination. At high concentrations of ABA (50, 100 μM), the quantitative contribution of polysomes in the total ribosomal fraction was almost 100% of the amount of polysomes before digestion and the modifications observed consisted mainly of the shift of the so-called heavy polysomes towards light polysomes, containing a few ribosomes. Within each polysomal population, cytoskeleton-bound polysomes (CBP and CMBP) were the most stable, which may imply that the bonds between polysomes and these protein filaments, created in all eukaryotic cells increased their stability. It is assumed that mRNAs are stabilised or destabilised by interaction of proteins with their various sequences. A plant hormone may depress or elevate the quantities of these proteins, thus regulating the stability of different mRNAs. The results confirm the multi-faceted mechanism of ABA-induced response, where one of the constituents is the effect of ABA on the stability of mRNAs molecules. The co-ordinated regulation of mRNAs synthesis and their stability provide plants with improved adaptability.     

Effects of different land use patterns on nifH genetic diversity of soil nitrogen-fixing microbial communities in Leymus Chinensis steppe

Biological nitrogen fixation through prokaryotic microbe is an important source of nitrogen been input into many natural ecosystems. In this study the active diazotrophic community was investigated in the three treatments of mowed, grazed and enclosed Leymus chinensis steppes in Hulunbeier grassland of Inner Mongolia by using approaches of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR–DGGE) and sequence analysis. The community structure and diversity of the bacterial groups from the different samples was further analyzed by using different techniques, such as statistical analysis and diversity index evaluation of the band patterns etc. The results showed that grazing activity significantly reduced the number of species and quantities of nitrogen-fixing microorganisms, as well as the nifH gene diversity. However, enclosed plots had the lowest diversity of nifH gene. While the highest one found in mowing plots. A total of 30 sequences representing 25 different sequence types were recovered from the DGGE gels after phylogenetic constructions. The results also revealed that most sequences were coming from Alphaproteobacteria of Proteobacteria, and characterized by sequences of members of Rhodobacter, Bradyrhizobium, Mesorhizobium, Rhodopseudomonas, Xanthomonas, Azospirillum, Gluconacetobacter, Methylobacterium and Methylocystis. Symbiotic nitrogen-fixers existed in grazing, mowing and enclosed plots accounted for 21.4%, 47.3% and 31.3% respectively in their dominant nitrogen-fixing bacteria. The result of principal components analysis showed that the influence of different land use patterns on nitrogen-fixing microbial communities composition can be ordered as grazing plots > enclosed plots > mowing plots. Nitrogen-fixing microbial communities in L. chinensis steppe were significantly (P < 0.05) influenced by the levels of nitrate nitrogen, total phosphorus, available phosphorus contents and pH value when canonical correspondence analysis was employed to identify relationship between nifH gene and soil physicochemical factors under different land use patterns. The result obtained from correlation analysis showed that there was a significant (P < 0.05) negative relationship between the nitrate nitrogen and the total phosphorus content, furthermore, the available phosphorus content was strongly correlated (P < 0.01) with the pH value.     

Effects of different land use patterns on nifH genetic diversity of soil nitrogen-fixing microbial communities in Leymus Chinensis steppe

Biological nitrogen fixation through prokaryotic microbe is an important source of nitrogen been input into many natural ecosystems. In this study the active diazotrophic community was investigated in the three treatments of mowed, grazed and enclosed Leymus chinensis steppes in Hulunbeier grassland of Inner Mongolia by using approaches of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR–DGGE) and sequence analysis. The community structure and diversity of the bacterial groups from the different samples was further analyzed by using different techniques, such as statistical analysis and diversity index evaluation of the band patterns etc. The results showed that grazing activity significantly reduced the number of species and quantities of nitrogen-fixing microorganisms, as well as the nifH gene diversity. However, enclosed plots had the lowest diversity of nifH gene. While the highest one found in mowing plots. A total of 30 sequences representing 25 different sequence types were recovered from the DGGE gels after phylogenetic constructions. The results also revealed that most sequences were coming from Alphaproteobacteria of Proteobacteria, and characterized by sequences of members of Rhodobacter, Bradyrhizobium, Mesorhizobium, Rhodopseudomonas, Xanthomonas, Azospirillum, Gluconacetobacter, Methylobacterium and Methylocystis. Symbiotic nitrogen-fixers existed in grazing, mowing and enclosed plots accounted for 21.4%, 47.3% and 31.3% respectively in their dominant nitrogen-fixing bacteria. The result of principal components analysis showed that the influence of different land use patterns on nitrogen-fixing microbial communities composition can be ordered as grazing plots > enclosed plots > mowing plots. Nitrogen-fixing microbial communities in L. chinensis steppe were significantly (P < 0.05) influenced by the levels of nitrate nitrogen, total phosphorus, available phosphorus contents and pH value when canonical correspondence analysis was employed to identify relationship between nifH gene and soil physicochemical factors under different land use patterns. The result obtained from correlation analysis showed that there was a significant (P < 0.05) negative relationship between the nitrate nitrogen and the total phosphorus content, furthermore, the available phosphorus content was strongly correlated (P < 0.01) with the pH value.     

Secretome profiling reveals temperature-dependent growth of Aspergillus fumigatus

Aspergillus fumigatus is a ubiquitous opportunistic fungus. In this study, systematic analyses were carried out to study the temperature adaptability of A. fumigatus. A total of 241 glycoside hydrolases and 69 proteases in the secretome revealed the strong capability of A. fumigatus to degrade plant biomass and protein substrates. In total, 129 pathogenesis-related proteins detected in the secretome were strongly correlated with glycoside hydrolases and proteases. The variety and abundance of proteins remained at temperatures of 34°C–45°C. The percentage of endo-1,4-xylanase increased when the temperature was lowered to 20°C, while the percentage of cellobiohydrolase increased as temperature was increased, suggesting that the strain obtains carbon mainly by degrading xylan and cellulose, and the main types of proteases in the secretome were aminopeptidases and carboxypeptidases. Only half of the proteins were retained and their abundance declined to 9.7% at 55°C. The activities of the remaining β-glycosidases and proteases were merely 35% and 24%, respectively, when the secretome was treated at 60°C for 2 h. Therefore, temperatures 60°C restrict the growth of A. fumigatus.     

拉杰沙希大学校园药用植物菌根研究

Forty different medicinal plants were investigated for arbuscular mycorrhizal association in the Rajshahi University Campus in Bangladesh. The results indicated that 35 different plants were infected by AM (arbuscular mycorrhizal) fungi as found by trypan blue staining procedure. The percentage of root colonization by AM fungi varied from 13.3% to 100%. Mangifera indica and Morus indica have maximum percentage of colonization (100%). The intensity of root colonization were abundant in the plants belonging to the families Anacardiaceae, Asclepiadaceae, Moraceae, Leguminosae and Apocynaceae whereas the intensity of colonization of crop roots were moderate and poor belonging to Gramineae and Leguminosae. The presence of greater number of spore in soil was always associated with the incidence of abundant mycelia. In plant roots the formation of spore and mycelia was restricted by low pH. Number of mycorrhizal fungus spores ranged between 35 to100 per 100g air dried soil in different family respective soils. The frequency of mycorrhizal fungus infection showed positive correlation with soil pH, moisture, water holding capacity, texture, total nitrogen, organic carbon, phosphorus, calcium, potassium, and magnesium. Especially phosphorus and nitrogen in the soil greatly influenced the plant root infection by AM fungi.     

Transcriptional silencing and developmental reactivation of cry1Ab gene in transgenic rice

One transgenic rice line lacking CrylAb expression product was screened in the progenies of Agrobacterium-transformed transgenic rice variety Zhong 8215 with a cry1Ab gene under field releasing conditions by using GUS histochemical assay and Western blot. Molecular hybridization results revealed that the crylAb gene was silenced in the transgenic rice variety Zhong 8215 and two copies of ubiquitin promoter were integrated into the rice genome. The silencing of crylAb gene in transgenic rice was found to be due to the methylation of the ubiquitin promoter as revealed by methylation analysis. Meanwhile, different concentrations of demethylation reagent 5-azacytidine combining with different treatment time were employed to treat the silenced transgenic rice seeds. The results indicated that 5-azacytidine could reactivate 8%-30% of the silenced transgenic rice plants and the expression level of the reactivated cry1Ab transgene could reach as high as 0.147% of the total soluble protein. Treatment with low con     

Nutritional Composition and Assessment of Gracilaria lemaneiformis Bory

The chemical composition, mineral elements, vitamins, free fatty acids and amino acid content of the edible red alga Gracilaria lemaneiformis Bory, grown in the sea near Nan＇ao island, Guangdong Province, were analyzed in the present study. Gracilaria lemaneiformis Bory showed a total sugar content of 14.65%. The protein content was 21%, of which approximately 41% was determined to be essential amino acids （EAA）. The major amino acid components were glutamic acid, leucine, arginine, and alanine. Of the EAA assayed, methionine and cysteine appeared to be the most limiting amino acids compared with the EAA pattern provided by Food and Agricultural Organization of the United Nations. The total lipids content was 0.87% and comprised a high composition of unsaturated fatty acids （61%）, mainly as linoleic acid and oleic acid, and a little amount of polyunsaturated fatty acid; palmitic acid was the main component （39%） of saturated acids. Relatively high levels of vitamin C, iodine, phosphorus, and zinc were also present in G. lemaneiformis. The nutritional composition between G. lemaneiformis and Nostoc flagelliforme, a rare alga that is widely eaten in Chinese society, was compared. The results suggest that N. flagelliforme can be substituted for by G. lemaneiformis, not only because of their similar shape, but also because of their approximate nutritional composition. Gracilaria lemaneiformis may possibly serve as a potential healthy food in human diets in the future.     

Structure of the Phytoplankton Community and Its Relationship to Water Quality in Donghu Lake, Wuhan, China

The phytoplankton community structure, in terms of species composition, total standing crop,and abundance of the dominant algal species, at four stations in Donghu Lake, Wuhan, China, was investigated monthly from January 1994 to December 1996. A total of 260 taxa was observed, of which Chlorophyta (106 taxa) contributed the highest portion of the total number of taxa, followed by Bacillariophyta (82 taxa)and Cyanophyta (32 taxa). The total standing crop measured by means of chlorophyll a content, cell density,and cell biovolume, as well as the abundance of the dominant species, declined in the order of Station I to Station Ⅳ. Seasonal changes of the standing crop varied greatly among the four stations. Although the cell density at the four stations showed a single peak within a year, the peak density varied from July to November, dependent on the sampling year and the station. For chlorophyll a content and cell biovolume,multiple peaks were observed at Stations Ⅰ and Ⅱ, but a single peak was found at Stations Ⅲ and Ⅳ. The phytoplankton community structure indicated that the trophic status was the highest at Station Ⅰ (most eutrophic), followed by Station Ⅱ; Stations Ⅲ and Ⅳ were the least trophic areas. The long-term changes in phytoplankton community structure further suggested that changes in phytoplankton community structure were correlated with water quality, and eutrophication of Donghu Lake had been aggravated since the 1950s.     

扁蓄总黄酮含量的测定

以35％乙醇为提取溶剂,聚酰胺吸附提纯,芦丁为标准品,用分光光度法于510nm处测定了扁蓄各部位的总黄酮含量。结果表明：扁蓄全草总黄酮含量为4．349％,根为7．115％,茎为5．454％,叶为3．544％。     

Oxygen transfer and culture characteristics of self-immobilized Solanum aviculare aggregates

Oxygen transfer characteristics of self-immobilized Solanum aviculare cells were measured using aggregates 3.0 to 12.5 mm in diameter. Apparent specific oxygen uptake rates in the absence of external boundary layers varied from 5.9 x 10(-11) to 8.5 x 10(-7) kg kg(-1) s(-1) dry weight, but did not decline continuously with increasing particle size. The effective diffusivity of oxygen in deactivated aggregates increased with particle diameter, varying from 5.0 x 10(-11) to 1.0 x 10(-9) m(2) s(-1) or between 2% and 40% of the molecular diffusivity in water at the same temperature. Gas spaces detected in the larger aggregates were confined to the central core and were not distributed throughout the tissue to facilitate oxygen transfer. Oxygen consumption rates in the absence of diffusional limitations were estimated using the relationship between the observable Thiele modulus and effectiveness factor for zero-order reaction. The calculated results indicated severe oxygen limitations in the aggregates, but were inconsistent with the observation that relatively large S. aviculare aggregates contained a high fraction of viable cells and were capable ofactive growth and steroidal alkaloid synthesis. This work suggests that oxygen delivery is facilitated in living plant cell aggregates by mechanisms which depend on metabolic activity and which do not function in deactivated cells. (c) 1995 John Wiley & Sons Inc.     

Phenotypic Plasticity in the Annual Weed Polygonum aviculare

Reaction norms of fourteen life history and morphological traits were investigated in four tetra- and two hexaploid genotypes of the annual weed species complex, Polygonum aviculare. The plants were cultivated in six treatments consisting of factorial combinations of three pot sizes and two fertility levels. All characters, except life span, were plastic but the relative importance of genotype (G), treatment (T) and interaction (G × T) to total variance was strongly trait-specific. Consistent genetic differentiation, not correlated with ploidy level, was found in metamer size and life history: genotypes originating from trampled sites had smaller metamers and shorter shoots while those originating from sites with a short growing season, due to weeding activities, had a shorter life span, an earlier flowering date and a higher biomass allocation to reproduction compared to genotypes from less disturbed sites. Significant variation was found in reaction norms for all characters, including a lower amount of plasticity in metamer size in genotypes with numerous metamers and a lower amount of plasticity in total weight in shortlived genotypes. This suggested that variation in phenotypic plasticity reflected developmental constraints imposed by contrasting life span and metamer size in different genotypes. There was no evidence for niche differentiation along the soil resource gradient, suggesting that the species is comprised of “general purpose” genotypes with respect to soil fertility. It is concluded that the Polygonum aviculare complex has evolved a “dual” adaptive strategy i.e. a combination of genetic polymorphism and high phenotypic plasticity.     

Evidence that direct DNA uptake through cut shoots leads to genetic transformation of Solanum aviculare Forst

The reporter genes GUS, NPTII and BAR, either separately or in combination, have been exploited to determine if DNA which can directly enter plants, circulate within the plant and enter nuclei, can also integrate into the genome in a manner which will permit gene expression. Feeding of either seed-derived or adventitious cut shoots of Solanum aviculare with the GUS gene followed by rooting of the shoots and growing on, resulted in all tissues of the plant showing GUS activity as detected cytochemically. Southern blot analysis of plants derived from the adventitious shoots confirmed the presence of the reporter gene in roots. Reporter gene expression was observed also in the F1 generation. If GUS and NPTII or GUS, NPTII and BAR were fed together, then in each case it was possible to have both expression and Southern blot confirmation of each of the genes. There was a relatively high rate of transformation of approximately 5% of the fed stems across all experiments conducted during the present study.     

Biotransformation of (−)-limonene using Solanum aviculare and Dioscorea deltoidea immobilized plant cells

The biotransformation course of S-(–)-limonene by Solanum aviculare and Dioscorea deltoidea plant cells was studied using 5 different immobilization methods (entrapment into alginate, carrageenan and pectate gels, binding to polyphenyleneoxide and permeation into polyurethane foam). All techniques, with exception of permeation into pre-formed matrix, affected the product ratio. The main products were cis- and trans-carveol and carvone.     

Sensitivity of Polygonum aviculare seeds to light as affected by soil moisture conditions

BACKGROUND AND AIMS: It has been hypothesized that soil moisture conditions could affect the dormancy status of buried weed seeds, and, consequently, their sensitivity to light stimuli. In this study, an investigation is made of the effect of different soil moisture conditions during cold-induced dormancy loss on changes in the sensitivity of Polygonum aviculare seeds to light. METHODS: Seeds buried in pots were stored under different constant and fluctuating soil moisture environments at dormancy-releasing temperatures. Seeds were exhumed at regular intervals during storage and were exposed to different light treatments. Changes in the germination response of seeds to light treatments during storage under the different moisture environments were compared in order to determine the effect of soil moisture on the sensitivity to light of P. aviculare seeds. KEY RESULTS: Seed acquisition of low-fluence responses during dormancy release was not affected by either soil moisture fluctuations or different constant soil moisture contents. On the contrary, different soil moisture environments affected seed acquisition of very low fluence responses and the capacity of seeds to germinate in the dark. CONCLUSIONS: The results indicate that under field conditions, the sensitivity to light of buried weed seeds could be affected by the soil moisture environment experienced during the dormancy release season, and this could affect their emergence pattern.     

Biotransformation of (S)-(−)- and (R)-(+)-limonene using Solanum aviculare and Dioscorea deltoidea plant cells

(S)-(−)- and (R)-(+)-limonene was transformed to carvone via corresponding cis- and trans-carveol using Solanum aviculare and Dioscorea deltoidea plant cells. Both carveols and carvone formed were racemic in all biotransformations.     

Antifungal stress metabolites from Solanum aviculare

The steroidal alkaloids 5β-solasodan-3-one and solasodenone were isolated as antifungal stress metabolites from leaves of Solanum aviculare stressed by vacuum infiltration with water. The constitutive leaf alkaloids, solasodine and solamargine, also showed antifungal activity.     

Changes in the light sensitivity of buried Polygonum aviculare seeds in relation to cold-induced dormancy loss: development of a predictive model

The effect of cold (stratification) temperature on changes in the sensitivity of Polygonum aviculare seeds to light was investigated. Seeds buried in pots were stored under stratification temperatures (1.6, 7 and 12 degrees C) for 137 d. Seeds exhumed at regular intervals during storage were exposed to different light treatments. Germination responses obtained for seeds exposed to different light treatments and stratification temperatures were used to develop a model to predict the sensitivity of buried seeds to light. Seed sensitivity to light increased as dormancy loss progressed, showing the successive acquisition of low-fluence responses (LFR), very low-fluence responses (VLFR), and the loss of the light requirement for germination for a fraction of the seed population. These changes were inversely correlated to stratification temperature, allowing the use of a thermal time index to relate observed changes in seed light sensitivity to stratification temperature. The rate of increase in sensitivity of P. aviculare seeds to light during stratification is inversely correlated to soil temperature, and these changes in light sensitivity could be predicted in relation to temperature using thermal-time models.