Xinglin Li

Physicochemical properties of starches from two different yam (Dioscorea opposita Thunb.) residues

The starches obtained from two different yam residues, which were treated with alkali(starch-A) or enzyme (starch-E), were studied and compared with yam starch isolated using ordinary method (starch-O) for morphological, crystalline pattern, thermal, and pasting properties. The results revealed that the amylose content of three starches ranged from 19.47 to 22.17%. The granule surfaces of starch-A and starch-E were as smooth as that of starch-O. The crystalline pattern of the three starches was a C-type. The transition temperatures (To, Tp and Tc) varied from 70.11 to 73.64, 79.23 to 81.74, and 84.30 to 86.65 oC, respectively. The starch-E showed the highest Δ Hgel, followed by the starch-A, while it was lowest for the starch-O. According to the viscosity measurement, starch-O had the lowest pasting temperature, highest peak viscosity and breakdown viscosity, which were contrary to those of starch-E.

Identification of metabolic profiling of cell culture of licorice compared with its native one

AbstractGlycyrrhiza uralensis has long been used as a flavoring and sweetening agent in food products. In the last ten years, suspensions of Glycyrhiza cells have been successfully established. However, there is no report of full metabolic profiling research on these cells. To identify their composition we used HPLC–DAD coupled with ESI(+/−)–MSn to compare the constituents of cultured Glycyrhiza (CG) cells with those the native cells (NG). We identified 60 compounds including flavonoids, phenols, and triterpenoids. Among these compounds, 42 occurred both in NG and CG, nine were present in NG only and nine were present in CG alone. The number of the triterpenoid aglycones without glycones in CG was smaller than that in NG. The number of flavanone, isoflavone, isoflavan, and benzenoid compounds was also smaller in CG than that in NG, whereas the number of pterocarpans was much higher. Although differences existed between CG and NG, the extract of CG was similar to that of NG. With the development of cell suspension culture-based biotransformation, cell culture of Glycyrrhiza has the potential to be more profitable than field cultivation in some areas.

De novo Sequencing and Transcriptome Analysis Reveal Key Genes Regulating Steroid Metabolism in Leaves, Roots, Adventitious Roots and Calli of Periploca sepium Bunge

Periploca sepium Bunge is a traditional medicinal plant, whose root bark is important for Chinese herbal medicine. Its major bioactive compounds are C21 steroids and periplocin, a kind of cardiac glycoside, which are derived from the steroid synthesis pathway. However, research on P. sepium genome or transcriptomes and their related genes has been lacking for a long time. In this study we estimated this species nuclear genome size at 170 Mb (using flow cytometry). Then, RNA sequencing of four different tissue samples of P. sepium (leaves, roots, adventitious roots, and calli) was done using the sequencing platform Illumina/Solexa Hiseq 2,500. After de novo assembly and quantitative assessment, 90,375 all-transcripts and 71,629 all-unigenes were finally generated. Annotation efforts that used a number of public databases resulted in detailed annotation information for the transcripts. In addition, differentially expressed genes (DEGs) were identified by using digital gene profiling based on the reads per kilobase of transcript per million reads mapped (RPKM) values. Compared with the leaf samples (L), up-regulated genes and down-regulated genes were eventually obtained. To deepen our understanding of these DEGs, we performed two enrichment analyses: gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Here, the analysis focused upon the expression characteristics of those genes involved in the terpene metabolic pathway and the steroid biosynthesis pathway, to better elucidate the molecular mechanism of bioactive steroid synthesis in P. sepium. The bioinformatics analysis enabled us to find many genes that are involved in bioactive steroid biosynthesis. These genes encoded acetyl-CoA acetyltransferase (ACAT), HMG-CoA synthase (HMGS), HMG-CoA reductase (HMGR), mevalonate kinase (MK), phosphomevalonate kinase (PMK), mevalonate diphosphate decarboxylase (MDD), isopentenylpyrophosphate isomerase (IPPI), farnesyl pyrophosphate synthase (FPS), squalene synthase (SS), squalene epoxidase (SE), cycloartenol synthase (CAS), sterol C-24 methyltransferase (SMT1), sterol-4alpha-methyl oxidase 1 (SMO1), sterol 14alpha-demethylase (CYP51/14-SDM), delta(14)-sterol reductase (FK/14SR), C-8,7 sterol isomerase (HYD1), sterol-4alpha-methyl oxidase 2 (SMO2), delta(7)-sterol-C5(6)-desaturase (STE1/SC5DL), 7-dehydrocholesterol reductase (DWF5/DHCR7), delta (24)-sterol reductase (DWF1/DHCR24), sterol 22-desaturase (CYP710A), progesterone 5beta-reductase (5β-POR), 3-beta-hydroxysteroid dehydrogenase (3β-HSD). This research will be helpful to further understand the mechanism of bioactive steroid biosynthesis in P. sepium, namely C21 steroid and periplocin biosynthesis.

Three dimensional approach to investigating biological effects along energetic ion beam pathways

Heavy ion beams have many exciting applications, including radiotherapy of deep-seated tumors and simulation tests of space irradiation for astronauts. These beams often use a feature that concentrates the energy deposition largely along the end of the energy pathway, leading to different distributions of biological effects along the axial direction. Currently, there is relatively little information regarding the radial directional difference of biological effects along the heavy ion paths. This study utilized a filter membrane that was quantatively applied with cells to demonstrate a 3D distribution model of irradiation on biological effects in living organisms. Some results have indicated that there is excitatory effect on the non-irradiated regions with energetic ions, which may give new insights into the distribution of biological effects along the paths of heavy ion beams with mid-high energy.

Lentinan promotes the root of Brassica CampestrisL.

The aim of this work was to study the effect of lentinan on Brassica campestris L (rape). Spraying on the leaves of lentinan B. campestris L. at 0.05×10-6 g ml-1 concentration significantly promoted the root elongation (P＜0.05). The results for the first time showed that lentinan could prolongate roots as a new plant hormone.

Screening Autotetraploid Plantlets of Glycyrrhiza uralnesis Fisch by Colchicine-Treated Bud Culture

To screen effective and useful autopolyploid of Glycyrrhiza uralnesis Fisch, the buds were used to dip in the medium with colchicine at different concentrations for different times. The treated buds were transferred to pots with perlite to grow at room temperature. After 2 weeks, the root tips from the cultured seedlings were cut to observe their cell morphology and chromosome counts, and the individual contained four chromosome groups harvested as an autotetraploid. The results indicated that, the colchicine of low concentration might promote the bud′s development, whereas high concentration colchicine is harmful for the buds of Glycyrrhiza uralnesis Fisch. Moreover, over 30 % autotetraploids might be obtained using 0.15 or 0.20 % of colchicine for 12–36 h, but in comparison with the diploids, the plantlets of many autotetraploids became badly weak at first generation. Therefore, the autotetraploids preliminary obtained will be faced to strictly screen according to agricultural traits and effective component.

Isolation and Identification of Saline Tolerance Phosphate-Solubilizing Bacteria Derived from Salt-affected Soils and Their Mechanisms of P-solubilizing

The salt-affected soils of beach from Tianjin China were sampled to screen the saline tolerance phosphate-solubilizing bacteria (SA-T-PSB) using inorganic phosphorous medium. On basis of the phenotypic characterization and 16S rRNA gene sequencing, 4 isolates with the highest PSA, B1114, B1213, B1303, and J101 were identified as Enterobacter ludwigii, Pantoea ananatis, Pseudomonas psychrotolerans, and Gluconobacter frateurii, respectively. Subsequently, aimed to assaying the mechanisms of P-solubilizing, organic acid types of the 4 isolates were determined by high performance liquid chromatography. The results showed that all 4 isolates mainly secreted gluconic acid. The effect of carbon and nitrogen source on P-solubilization activity of the strains also indicated that the production of gluconic acid is the main mechanisms of P-solubilizing.

A fresh method of DNA transformation to the seeds irradiated by 60 Co without the use of antibiotic selection

To find out a simpler method that can directly transfer the aim gene into plant genomes, the purple medic seeds irradiated by 60 Co with 0.375 Gy were transformed by linear DNA containing a β-glucuronidase (GUS) gene (as an aim gene), a betaine aldehyde dehydrogenase (BADH) gene (as a selectable marker) and two pairs of both CaMV35S promoter and Nos terminator. Subsequently, the seeds were planted and grown in perlite media watered with NaCl solution as a kind of selective compound. The results showed that, positive frequency of PCR identification by the GUS gene or the BADH gene was higher than 53.2 and 89.5% in T 0 and T 1 generations, while GUS staining rate was higher than 50%; whereas five T 1 plants assayed by southern hybridization all showed positive reaction. In conclusion, by this method, transgenic plants may be easily obtained with the antibiotic markers for free; moreover, the plant regeneration-system must not be erected by directly transforming the seeds. Key words : DNA transformation, irradiated seeds, purple medic, salt screening.