Effect of ABA,arginine and sucrose on protein content of date palm somatic embryos

Abscisic acid (ABA), arginine and sucrose were evaluated for their effects on the morphology, germination rates and protein content of date palm somatic embryos (SE). Different concentrations of these supplements in the culture medium were used. The comparative study of SE length and thickness between treated and untreated SE revealed no differences, except for ABA (20 μM), which increased thickness. A decrease of water content (WC) in favor of an increase in dry weight (DW) was observed in all treated SE, especially with sucrose (90 g l⁻¹) and ABA (20 μM). Only ABA (20 and 4 μM) caused a proliferation rate of the cultures higher than those in the control. Although all the tested compounds increased protein content, ABA (20 μM) was more effective in protein enrichment than arginine and sucrose treatments. The SDS-PAGE protein profiles showed a significant difference between treated and untreated SE. A protein band of 22 kDa, identified as glutelin in a previous work, was accumulated after treatment with 20 μM ABA or 3 mM arginine. These findings may contribute to further understanding of the mechanisms involved in the accumulation of specific storage proteins in several plants.     

蓖麻毒素基本生物学特性分析

[目的]对蓖麻毒素分子量、等电点和氨基酸序列等基本生物学特性进行分析。[方法]以内蒙古通辽地区所产蓖麻哲蓖2号为对象,利用毛细管电泳技术、分子生物学技术、毒性检测等免疫学技术对其毒素基本生物学特性进行检测分析。[结果]试验中所用蓖麻毒素的等电点为6.49,分子量为61.9kD,其氨基酸序列与网上公布序列相比,A链有22个位点发生变异,B链无变异;小鼠口服LD50为5.0mg/kg,腹腔注射LD50为4.6μg/kg,淋巴细胞IC50为3μg/ml。[结论]该研究为深入了解蓖麻毒素生物学性质提供依据,同时为不同产地蓖麻毒素毒性及其他性质的差异比较奠定基础。     

Effect of size reduction by freeze-milling on processing properties of beta-glucan oat bran

An effect of freeze-milling on processing properties of beta-glucan oat bran has been evaluated. A comparison with existing, patented methods of high molecular weight oat beta-glucan has been carried out. The new method employs raw material pre-treatment with freezing and milling in a hammer mill, resulting in significant reduction of particle size – 89% was between 80 and 50 μm in comparison with initial material when 79% were between 250 and 200 μm. Reduction of particle size also improved some process parameters of extraction technology – 30% improvement in fat removal during first stage of beta-glucan recovery was observed. The achieved pilot plant yield of product containing beta-glucan extraction was 64,03%, purity (ie. beta-glucan content), of achieved product was 84,4% and average molecular weight was about 69,500 g/mol.     

116MW循环流化床锅炉房的电气优化设计

随着城镇供热的迅速发展,116MW循环流化床锅炉被普遍应用。本文从工程应用和规程规范出发,对116MW循环流化床锅炉房电气设计提出了优化设计方案。     

600MW汽轮机单顺序阀切换时的异常分析及处理

某厂600MW汽轮机阀门控制方式由单阀切换为顺序阀控制时EH油压波动、轴承温度异常现象,无法切换为顺序阀方式运行。通过分析研究,修改阀门开启顺序、修改阀门特性曲线,机组已安全稳定的处于顺序阀控制方式下,取得了良好的经济效益。     

Chitosan physico–chemical properties modulate defense responses and resistance in tobacco plants against the oomycete Phytophthora nicotianae

Enzymatic defense responses and protection against Phytophthora nicotianae were studied in tobacco plants treated with chitosan of different molecular weights (MW) and degrees of acetylation (DA). The concentration and mode of chitosan application affected enzymatic induction in tobacco leaves. β-1,3-Glucanase (EC 3.2.1.6) activity required 10 times the polymer concentration relative to the oligochitosan mixture to induce the highest activity above control when treated by foliar spray, indicating the influence of molecular weight in this response. PAL (EC 4.3.1.5) and POD (EC 1.11.1.6) activities increased above control as a result of the influence of polymer degree of acetylation when treatments were applied by foliar spray. A higher DA favored PAL activity, whereas a lower DA induced higher POD activity. Using an in vitro bioassay, it was found that the three chitosan compounds caused a reduction of the infection index of P. nicotianae in tobacco plants that was dependent on elicitor concentrations. There was a significant relationship between the reduction of the infection index and an increase in PAL activity when chitosan was applied by foliar spray and by substrate drench to the plant rhizosphere. These results demonstrate the influence of chitosan physico–chemical properties in plant-induced resistance and the relevance of particular responses in plant protection against pathogens.     

Physico-chemical description of bread dough mixing using two-dimensional near-infrared correlation spectroscopy and moving-window two-dimensional correlation spectroscopy

NIR spectroscopy presents a huge interest in exploring chemical changes during dough mixing. The aim of the present study is to investigate the potential of 2D correlation spectroscopy (2D COS) and moving-window 2D (MW2D) correlation spectroscopy to explore the time dependence of NIR spectral responses during wheat flour dough mixing. NIR spectra were continuously recorded (between 1400 and 2325 nm) during mixing of bread type-dough (based on flour, water and yeast), using an FT-NIR spectrometer with a deported probe. The probe was positioned inside the mixer in contact with the dough. The 2D spectra calculated using raw and second derivative NIR spectra were interpreted in terms of physico-chemical events. Nine different industrial flours were used as raw material to validate the analysis. The results obtained using the 2D COS and the MW2D methods give the possibility to ascribe chemical vibrations (starch, water and gluten) to NIR absorbance changes occurring during dough mixing. The analysis of the NIR spectra identified wavelength shift associated to both dough “free water” and protein secondary structure modifications. During this study, only the MW2D method allowed to identify clearly the time dependence of physico-chemical mechanisms from NIR variation bands.     

Development of zygotic and somatic embryos of Phoenix dactylifera L. cv. Deglet Nour: Comparative study

In order to improve somatic embryogenesis production in date palm Phoenix dactilyfera L. cv. Deglet Nour (DN), a comparative study between somatic (SE) and zygotic (ZE) embryos developments was carried out. The data showed that ZE maturation occurred from 10 to 19 weeks after pollination (WAP). During this period, the fresh weight (FW) and the dry weight (DW) of ZE increased progressively to reach a maximum level at 19 WAP. SE development occurred in three distinct stages. The DW remained constant during the two first stages, and declined slightly during the third and final stage. Embryo protein analysis revealed significant differences between ZE and SE. The ZE total protein level was initially low and increased to the maximum at mature stage. However, no significant change in total protein was detected during SE development. SDS-PAGE analysis showed a poor protein profile for SE, compared to that of ZE. In the latter, a 22 kDa protein was identified by N-terminal sequencing as a glutelin. This protein was accumulated rapidly during early development and remained at a relatively constant level during ZE development, and then declined progressively 12 days after embryo germination (DG). This protein seems to be absent in SE.     

Removal Characteristics of DOM in Landfill Leachate by Fenton SBR Process

The removal effect of dissolved organic matter（DOM）in landfill leachate by Fenton SBR treatment process was investigated. And the changes of DOM molecular weight (MW) and the fractions humic acid (HA), fulvic acid (FA) and hydrophilic (HyI) in combined process was also analyzed. It is shown that the removal of COD 、DOC and UV254 was 79.1% 、73.6% and 92.9% with the combined process, respectively. The removal of COD was above 80% except for those with the molecular of 10～4 ku. The removal order of DOM fractions and three index of each fraction was HA>FA>HyI and UV254>COD>DOC, respectively.