生物质及其衍生糖类制备乳酸的研究进展

生物质资源是地球上产量最多、分布最广的可再生资源,利用农业废弃物等各种生物质制备高附加值平台化合物对解决能源危机和环境问题具有重要的意义。本文在相关研究现状的基础上,简要总结了发酵法、化学催化法等以生物质及其衍生糖类为底物制备乳酸的工艺方法,并对相应体系进行了分析,提出了这一领域中近期的热点及发展趋势,以期对后续研究提供参考。     

Effect of differently post-treated dewatered sewage sludge on β-glucosidase activity,microbial biomass carbon,basal respiration and carbohydrates contents of soils from limestone quarries

This work has evaluated the effects of thermally dried (TDS) or composted (CDS) dewatered sewage sludge on β-glucosidase activity, total (TCH) and extractable (ECH) carbohydrate content, microbial biomass carbon and basal respiration of soils from limestone quarries under laboratory conditions. Two doses (low and high) of the dewatered sludge (DS) or of the respective TDS or CDS were applied to a clayey and a sandy soil, both coming from working quarries. The soil mixtures and the controls (soils with no added sludge) were incubated for 9 months at 25°C and 30% of field capacity. The addition of sludge increased all the studied soil parameters, and the increase depended on the amount of sludge. Except in the case of TCH and ECH, the enhancing effect decreased with time, but at the end of incubation, parameters of the treated soils were higher than those of the control. The rank order of the initial stimulating effect was soil–TDS ≥ soil–DS ≥ soil–CDS, and probably, this order depended on the proportion of stable organic matter, which was the lowest in the TDS. Values of metabolic quotient (qCO₂) were higher at the lower dose, and they did not change during incubation in the CDS-treated soils. Both TCH and ECH were the parameters with the greatest significant sludge and dose effects. Basal respiration, microbial biomass carbon and β-glucosidase activity were the best measured parameters in distinguishing the long-term effects of the three sludge types over the soils.     

Effect of water stress conditioning on morphology,physiology and field performance of Pinus halepensis Mill. seedlings

Five-month-old Pinus halepensis Mill. seedlings were subjected to 4 irrigation treatments for 8 weeks. After the treatments, morphological and physiologicalattributes assessed included height, diameter, dry weight, water relations parameters, and determination of N, P, K, soluble carbohydrates, and starch concentrations. The remaining seedlings were field planted. Survival and height growth were recorded forfour growing seasons after planting. The mostsignificant effect of irrigation was onmorphology. Increased irrigation lead toseedlings with significantly higher height,root collar diameter and shoot and rootbiomass. Starch and soluble carbohydrateconcentrations were also affected byirrigation. However, parameters derived frompressure-volume curves were not significantlydifferent among treatments, nor were N, P, andK concentrations. There were no differencesamong treatments for survival in the field,which was highly related to summer rainfall. Incomparison, absolute and relative heightgrowth showed some significant but minordifferences among treatments.     

Improved RP‐HPLC and anion‐exchange chromatography methods for the determination of amino acids and carbohydrates in soil solutions

In spite of their low concentrations in soil solutions, low–molecular weight organic substances (LMWOS) such as amino acids, sugars, and uronic acids play a major role in the cycles of C and N in soil. With respect to their low concentrations and to possible matrix interferences, their analysis in soil leachates is a challenging task. We established two HPLC (high‐performance liquid chromatography) methods for the parallel determination of amino acids and carbohydrates in soil leachates. The pre‐column derivatization of amino acids with an o‐phthaldialdehyde (OPA) mercaptoethanol solution yields quantitation limits between 0.03 and 0.44 µmol L^–1 and S_D values of <8.3% (n = 9). High‐performance anion‐exchange chromatography (HPAEC) on a Dionex CarboPac PA 20 column with a NaOH acetate gradient combined with pulsed amperometric detection (PAD) was used for the determination of carbohydrates. The calibration curves obtained for 11 carbohydrates showed excellent linearity over the concentration range from 0.02 to 50.0 mg L^–1. Recovery studies revealed good results for all analytes (89%–108%). Interferences from Hg(II) salts and chloroform used for stabilization of the leachates did not occur with both chromatographic methods. The optimized method was successfully used for quantitative determinations of amino acids and carbohydrates in soil leachates.     

EFFECT OF PREVIOUS NITROGEN STARVATION ON NO3 − AND NH4 + UPTAKE AND ASSIMILATION ASSOCIATED WITH THE ENDOGENOUS SOLUBLE CARBOHYDRATE UTILIZATION IN MOROCCAN WHEAT SEEDLINGS

Uptake of the two forms of nitrogen NO₃ ^? and NH₄ ⁺ and nitrate reduction have been studied in two varieties of Moroccan wheat seedlings, cvs. Sais and Jouda, cultivated under controlled conditions in a hydroponic medium. The available form of nitrogen in the medium had a direct effect on the rate of nitrogen absorption. A brief nitrogen starvation increased the root length and stimulated accumulation of soluble carbohydrates, especially in the root tissues. A resupply of nitrogen stimulated ammonium and nitrate uptake and assimilation with higher mobilization of the soluble carbohydrates previously accumulated in root seedlings. It is suggested that root nitrogen and carbohydrate status might both regulate nitrate uptake and reduction in Moroccan wheat seedlings.

The seedlings raised with the nitrate supply accumulated nitrate in the vacuole as an osmoticum. Shoots are the preferential site for such accumulation. The accumulation of mineral nitrogen was absent in the seedlings cultivated with ammonium supply but was compensated by accumulation of soluble organic nitrogen.     

NS1基因主要抗原区的可溶性表达及其Dot-ELISA检测方法的建立

【目的】可溶性表达猪流感病毒(SIV)NS1基因主要抗原区(NS1′)蛋白,获得具有良好抗原性的NS1′蛋白,并初步建立检测NS1抗体的斑点酶联吸附试验(Dot-ELISA)方法,为鉴别诊断猪流感病毒感染猪与疫苗免疫猪奠定基础。【方法】以质粒pET28a-NS1为模板,PCR扩增NS1基因抗原性较好的区段NS1′,用EcoRⅠ和XhoⅠ双酶切后插入pET-32a(+),构建pET32a-NS1′,经PCR、EcoRⅠ和XhoⅠ双酶切及DNA测序鉴定后,转化大肠杆菌Rosetta,用IPTG诱导表达,纯化NS1′并免疫家兔制备多克隆血清,对其进行SDS-PAGE、Western blotting检测和免疫荧光分析,并以纯化的NS1′作为包被抗原初步建立Dot-ELISA检测方法。【结果】PCR扩增获得了长约250bp的H3N2SIV NS1′片段;成功构建了重组载体pET32a-NS1′;SDS-PAGE和Western blotting检测结果显示,融合蛋白NS1′大小约34ku,该蛋白可溶,能与感染SIV的猪血清特异性反应,并且用纯化蛋白NS1′制备的多克隆血清能识别293T细胞中表达的NS1,建立的Dot-ELISA检测方法可鉴别猪流感病毒感染猪与疫苗免疫猪。【结论】实现了H3N2SIV NS1′蛋白的可溶性表达,表达产物具有良好的抗原性,以NS1′作为包被抗原,建立了检测NS1抗体的Dot-ELISA方法。     

Interaction between water-soluble carbohydrate reserves and defoliation severity on the regrowth of perennial ryegrass (Lolium perenne L.)-dominant swards

A field-study was undertaken in Hamilton, New Zealand to determine if there was an interaction between water-soluble carbohydrate (WSC) reserve content and defoliation severity on the regrowth of perennial ryegrass-dominant swards during winter. Perennial ryegrass plants with either low or high WSC content were obtained by varying the defoliation frequency. At the third defoliation at the one-leaf stage and at the first defoliation at the three-leaf stage (harvest H₁), swards were mown with a rotary lawnmower to residual stubble heights of 20, 40 or 60 mm. All swards were then allowed to regrow to the three-leaf stage before again defoliating to their treatment residual stubble heights (H₂). Frequently defoliated plants contained proportionately between 0·37 and 0·48 less WSC in the stubble after defoliation, depending on the severity of defoliation. There was no interaction between WSC content and defoliation severity for herbage regrowth between harvests H₁ and H₂. Herbage regrowth was lower from swards containing low WSC plants compared with high WSC plants (2279 vs. 2007 kg DM ha⁻¹). Furthermore, swards defoliated to 20 or 40 mm had greater herbage regrowth compared with those defoliated to 60 mm (2266, 2249 and 1914 kg DM ha⁻¹ for swards defoliated to residual stubble heights of 20, 40 and 60 mm, respectively). Regrowth of perennial ryegrass was positively correlated with post-defoliation stubble WSC content within defoliation severity treatment, implying that WSC contributed to the defoliation frequency-derived difference in herbage yield. However, the effect of defoliation severity on herbage regrowth was not associated with post-defoliation stubble WSC content.     

重组日本乙型脑炎病毒NS1的可溶性表达及抗原性分析

根据日本乙型脑炎病毒(JEV)Whe株非结构蛋白质1(NS1)的基因序列,设计引物,利用反转录PCR从实验室保藏JEV Whe株中克隆NS1全长序列,并将其插入pET28a表达载体,构建重组表达质粒NS1-pET28a,转化大肠杆菌BL21(ED3),经IPTG诱导,得到可溶性表达的融合蛋白质His-NS1。结果表明,该融合蛋白质分子量为46ku,大量表达于上清中。镍离子亲和层析柱进行纯化得到His-NS1蛋白质,经Western-blot检测,证明其具有良好的免疫学活性,这为进一步研究JEV NS1的功能及应用奠定了基础。     

不同种源北美香脂杨苗木碳水化合物积累差异分析

对9个不同种源的北美香脂杨在加拿大温哥华扦插繁殖的苗木枝条进行分析,分另4测定带芽枝条可溶性糖、淀粉、糖组分的含量,扦插后萌发的叶干质量和根干质量。结果表明：不同种源枝条的可溶性糖和淀粉含量差异极显著;扦插生根和叶的干质量与淀粉含量间呈现正相关关系,与各地的地理位置（纬度、经度、海拔）无显著相关性;不同种源枝条内淀粉含量与其扦插生根特性呈正相关关系。     

Identification of the strain-specifically truncated nonstructural protein 10 of porcine reproductive and respiratory syndrome virus in infected cells

The nonstructural protein 10 (nsp10) of porcine reproductive and respiratory syndrome virus (PRRSV) encodes for helicase which plays a vital role in viral replication. In the present study, a truncated form of nsp10, termed nsp10a, was found in PRRSV-infected cells and the production of nsp10a was strain-specific. Mass spectrometric analysis and deletion mutagenesis indicated that nsp10a may be short of about 70 amino acids in the N terminus of nsp10. Further studies by rescuing recombinant viruses showed that the Glu-69 in nsp10 was the key amino acid for nsp10a production. Finally, we demonstrated that nsp10a exerted little influence on the growth kinetics of PRRSV in vitro.