土壤中钙结合和铁铝结合腐殖质的组成及结构特征

Calcium-bound and iron- and aluminium-bound humus extracted from different soils collected from north to south of China were characterized by chemical and spectroscopic methods. Meaningful differences in the composition and structure between them were revealed by ¹³C NMR, visible spectroscopy and elemental analysis. Results showed that the contents of carbon, hydrogen and nitrogen were higher in iron- and aluminium-bound humus than in calcium-bound humus while oxygen content in calcium-bound humus was shown to be higher. The calcium-bound humus had higher C/N and O/C ratios than iron- and aluminium-bound humus. The calcium-bound humic acid (HA1) showed higher E₄/E₆ ratios than iron- and aluminum-bound humic acid (HA2) while iron- and aluminum-bound fulvic acid (FA2) showed higher E₄/E₆ ratios than calcium-bound fulvic acid (FA1). An inverse relationship between E₄/E₆ ratios and aromaticity as determined by ¹³C NMR spectra was observed for HA and FA from black soil. The ¹³C NMR spectroscopy revealed that HA2 was more aromatic than HA1. On the other hand, FA1 exhibited a higher aromaticity than FA2.     

Extraction of humic-β-glucosidase fractions from soil

Humic compounds with -glucosidase activity were extracted from soil using tetrasodium pyrophosphate as extracting solution. Mixture of soil samples with 0.01 M pyrophosphate in a ratio of 1:5 (w/v), adjustment to pH 7.0–7.3, extraction for 18 h with reciprocating agitation, and bacteriological filtration after centrifugation were the optimum conditions for extraction of the -glucosidase complexes. Otherwise, experimental conditions for extraction indicated that the concentration and pH of pyrophosphate were the factors with the most influence on enzymatic extraction yields. The results indicated that the -glucosidase was extracellular and associated with soil humates.     

玉米(Zea mays L.)中单14号及亲本叶绿体的组分和功能比较

玉米中单１４号的叶绿体在叶绿素含量、光能吸收、电子传递速率、激发能分配和色素蛋白复合体组成等方面均优于两亲本。其叶绿素ａ、ｂ和总含量提高了３１％￣３６％；对光能吸收强度较大；光还原活力超过双亲２５．５％；分配到ＰＳＩ的激发能比亲本多１４７．１％；叶绿素蛋白复合体分析结果说明，其捕光色素蛋白复合体含量高于亲本。因而中单１４号比亲本在叶绿体的光合功能上显示优势。     

α-环糊精戊酸包合物的制备及释放动力学研究

采用改进的共沉淀法制备α-环糊精戊酸包合物。正交试验表明,制备α-环糊精戊酸包合物的最佳参数为:戊酸与α-环糊精的摩尔比为3:1,超声45 min,超声温度50℃,可获最大包合率为52.79%;通过扫描电镜、红外、XRD和CP-MAS 13C NMR对包合物结构进行表征,环糊精表观形态改变,C=O双键吸收峰出现,XRD衍射峰迁移和核磁碳谱戊酸化学位移出现,表明戊酸与α-环糊精包合物的形成;利用Avrami方程对α-环糊精戊酸包合物在不同条件下的释放情况进行分析,结果表明湿度越大,温度越高释放速度越快。     

The acquisition of phosphate by higher plants: Effect of carboxylate release by the roots. A critical review.

Phosphorus is one of the most limiting macronutrients for plant productivity in agriculture worldwide. The main reasons are the limited rock phosphate reserves and the high affinity of phosphate (P) to the soil solid phase, restricting the P availability to the plant roots. Plants can adapt to soils low in available P by changing morphological or/and physiological root features. Morphological changes include the formation of longer root hairs and a higher root : shoot ratio both parameters increasing the root surface which provides the shoot with P. This may be successful if the P availability in soil, i.e., the P concentration of the soil solution is not extremely low (> 1–2 µM P). If the P concentration of the soil solution is lower, the diffusive flux to the root surface will be very low and may not satisfy the P demand of the shoots. Under these conditions plants have developed strategies to increase the rhizosphere soil solution concentration by secreting mobilizing agents. The most effective way of P mobilization is the release of di‐ and tricarboxylic acid anions, especially oxalate and citrate. Citrate can accumulate in the rhizosphere up to concentrations up to 80 µmol g^?1 soil. Cluster root formation is an efficient way of carboxylate accumulation in the cluster root rhizosphere improving P mobilization. Cluster roots strongly improve the acquisition of the mobilized P. Considering a single root, around 80–90% of the mobilized P diffuses away from the root. From the rhizosphere of cluster roots, most of the mobilized P is taken up by the cluster roots. Both, the strong accumulation of carboxylates in and the effective P uptake from the cluster‐root rhizosphere are the basis of the unique ability of P acquisition by cluster root‐forming plants. Plants that do not form cluster roots, e.g., red clover, can also accumulate carboxylates in the rhizosphere. Red clover accumulates high quantities of citrate in the rhizosphere soil. Model calculations show that the release of citrate by red clover roots and its accumulation in the rhizosphere strongly improve P acquisition by this plant species in various soils. Similar results are obtained with alfalfa. In sugar beet, oxalate release can strongly contribute to P acquisition. In summary, P acquisition can be strongly improved by the release of carboxylates and should be taken as a challenge for basic and applied research.     

Sorption of iron‐cyanide complexes on goethite investigated in long‐term experiments

The iron‐cyanide complexes ferrocyanide, [Fe^II(CN)₆]^4–, and ferricyanide, [Fe^III(CN)₆]^3–, are anthropogenic contaminants in soil. We investigated their sorption on goethite, α‐FeOOH, in batch experiments in a time range from 1 d to 1 yr, their desorption by phosphate and chloride as well as their surface complexes on goethite by Fourier‐transform infrared spectroscopy (FTIR). The sorption of both complexes continued over the whole time range. Percent desorption of ferricyanide by phosphate decreased, whereas that of ferrocyanide increased until it amounted to approximately 87% for both complexes. By FTIR spectroscopy inner‐sphere complexation of both complexes on the goethite surface was indicated. With both complexes, a Berlin‐Blue‐like layer (Fe₄[Fe(CN)₆]₃) was formed initially on the goethite surface which disappeared with increasing reaction time. After at least 30 d reaction time, ferricyanide was the only sorbed iron‐cyanide complex detected even when ferrocyanide was initially added. This resulted from slow oxidation of ferrocyanide, most probably by dissolved oxygen. Based on all results, we propose that ferricyanide forms monodentate inner‐sphere complexes on the goethite surface.     

卵母细胞生发泡破裂(GVBD)发生前后脱卵丘细胞对猪卵母细胞体外成熟的影响

成熟卵母细胞的细胞质对供体细胞的重编程有作用,卵母细胞的成熟状态成为核移植过程的关键因素。为了研究卵母细胞体外成熟过程中卵母细胞生发泡破裂(germinal vesicle breakdown,GVBD)发生前后脱卵丘细胞对卵母细胞的影响,本研究采用猪(Sus scrofa)卵丘-卵母细胞复合体(cumulus-oocyte complexes,COCs)于体外培养,每隔5 h取卵母细胞采样,置于地衣红染液中染色,根据卵母细胞染色体构型的变化确定卵母细胞的分期,然后在21、27和42 h的卵母细胞进行脱卵丘细胞处理,观察极体数。体外培养不同时间压片观察结果表明,直径2~6 mm卵泡卵母细胞在体外培养时,2~17 h大部分卵母细胞处于GV期(88.30%~52.38%);22 h有63.25%的卵母细胞处于生发泡破裂至前中期(germinal vesical breakdown~premetaphaseⅠ,GVBD~pre-MⅠ);27 h处于中期Ⅰ(metaphaseⅠ,MⅠ)的卵母细胞最多(42.25%);32 h处于后期Ⅰ(anaphaseⅠ,AⅠ)的卵母细胞比例最多(29.90%);37 h处于末期Ⅰ(telophaseⅠ,TⅠ)的卵母细胞比例最多(40%);42 h绝大部分卵母细胞达到了中期Ⅱ(metaphaseⅡ,MⅡ)(72.81%)。分别采取21、27和44 h的卵母细胞进行脱卵丘细胞处理,发现21 h脱卵丘细胞后卵母细胞成熟率为25.56%,低于27 h处理卵的成熟率(34.33%),42 h脱卵丘细胞的卵母细胞的成熟率最高达到84.33%。结果说明,体外卵母细胞成熟过程中,卵丘细胞对卵母细胞的成熟具有重要意义,为进一步探讨和分析猪卵母细胞体外成熟培养的方法,改良体外培养体系,提高猪卵母细胞体外培养成熟率,进而提高胚胎体外培养质量提高奠定基础。     

Starch gelatinization and amylose–lipid interactions during rice parboiling investigated by temperature resolved wide angle X-ray scattering and differential scanning calorimetry

Starch gelatinization and formation of crystalline amylose–lipid complexes during the heat/moisture treatment step in rice parboiling were studied with temperature resolved wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) using flour from Puntal (24% apparent amylose) and Jacinto (12% apparent amylose) rice samples [66, 40 or 25% moisture content (mc)]. Temperature resolved WAXS showed that the crystallinity index (CI, i.e. the relative amount of A-type crystals) of non-parboiled rice flours at 66% mc, monotonically decreased between 65 °C (Puntal) and 70 °C (Jacinto) and 90 °C (both Puntal and Jacinto). These temperatures were in agreement with the respective onset and conclusion temperatures of the M₁ endotherm measured by DSC. At 40% mc, the CI decreased monotonically from 65 °C (Puntal) and 70 °C (Jacinto) until 105 °C. In DSC both M₁ and M₂ endotherms were present. The conclusion temperature of the M₂ endotherm was higher than 105 °C. At 25% mc, the CI decreased very gradually and A-type crystals were no longer present at 145 °C. Under these conditions, no DSC endotherms were detected. No type II amylose–lipid complexes were formed during heating at 66% mc. In contrast, at 40 and 25% mc, V_h-type crystals were formed from 100 and 130 °C, respectively. Non-parboiled white rice flour had a strong A-type pattern. Mildly parboiled rice had a clear A-type, with a weak V_h-type and B-type pattern. Severe parboiling resulted in partially crystalline systems with superimposed A-type, V_h-type and B-type crystals. It was concluded that the rice variety, the combination of mc and the moisture distribution in the rice kernel and the temperature during parboiling all impact the level and the types of crystals in the parboiled rice.     

Molecular encapsulation of flavours as helical inclusion complexes of amylose

The formation of helical inclusion compounds of amylose with different typical flavour compounds was optimised. Maximal guest molecule contents between 5.7 and 10.4 wt% in the complex were obtained. This corresponds to segments of 8–16 anhydroglucose units in the amylose helix per included guest molecule. Contents of this order of magnitude approach the maximum content of guest molecules possible in the core of the amylose helix. A method for determining the association constants for complexing using headspace gas chromatography was applied. Constants ranging from K=29–1080 l/mol were obtained. The association constant with the same guest molecule is strongly dependent on the origin and the chain length of the amylose.Flavours with low boiling points such as hexanal (b.p. 128 °C) form complexes which are completely stable under freeze-drying conditions and show long-term stability. Flavour release was only observed at high temperatures (80 °C). On addition of water, guest molecules are quickly released but with water activities of a_w=0.3—as found in normal dry food—the complexes are stable at room temperature.Complexes with two or more guest molecules show a remarkable influence on complexing ability induced by the co-inclusion compounds. The overall content of guest molecules is lower compared to that obtained with individual flavour compounds.     

Fulvic acid in foliar spray is more effective than humic acid via soil in improving coffee seedlings growth

ABSTRACT

Humic (HA) and fulvic (FA) acids improve the nutrient availability and uptake by plants but some aspects of their agronomic use still need to be clarified. The effects of HA soil application and FA foliar application on the growth, Zn and B uptake by coffee seedlings were evaluated. HA was added to an Oxisol at concentrations 0, 10, 25, 50, 75 and 100 mg kg^?1 (C-HA), in both limed (pH 6.2) and overlimed (pH 7.2) conditions. FA (0, 0.2, 0.5 and 1 g L^?1 C-FA) was applied to coffee leaves in three different application modes (M): with 0.3% Zn and 0.6% B supplied via foliar (M₁), 0.6% B and 1.2% Zn supplied via foliar (M₂) and 1.2 mg kg^?1 B and 6 mg kg^?1 Zn supplied via soil (M₃). HA addition in soil significantly (p < 0.05) reduced leaf B and Zn accumulation and coffee growth in both pH conditions. In the M₁ and M₂, FA application significantly (p < 0.05) increased the shoot growth at 0.59 and 0.45 g L^?1 and B accumulation at 0.96 and 0.45 g L^?1 C-FA. Foliar application of C-FA, instead soil application of C-HA, is a suitable practice to improve coffee seedlings growth and nutrition on Oxisol.