利用免疫共沉淀联合质谱技术筛选盐藻MAPK的互作蛋白

为进一步探究杜氏盐藻促有丝分裂原活化蛋白激酶(DsMAPK)的功能,采用免疫共沉淀联合质谱技术筛选盐藻MAPK的互作蛋白。将pGS21a-MAPK质粒转入大肠杆菌BL21中表达MAPK蛋白并制备多克隆抗体;将培养至对数生长期的盐藻细胞进行盐胁迫处理,然后提取盐藻总蛋白,并进行SDS-PAGE和Western blotting检测;以内源性靶蛋白为诱饵,将细胞总蛋白与MAPK抗体进行共孵育,将经蛋白A/G琼脂糖珠纯化的免疫共沉淀复合物进行质谱检测。结果表明,制备的多克隆抗体特异性良好;筛选出165种特有的差异蛋白。通过GO和KEGG分析发现,这些差异蛋白主要参与了新陈代谢、遗传信息的传递以及信号转导等生物学调控过程。蛋白质互作网络分析发现,直接与MAPK相互作用的蛋白有4种。本研究结果为深入研究杜氏盐藻响应盐胁迫的分子机制提供了参考。     

Properties of Flours and Starches as Affected by Rough Rice Drying Regime

Flours and starches from rough rice dried using different treatment combinations of air temperature (T) and relative humidity (RH) were studied to better understand the effect of drying regime on rice functionality. Rough rice from cultivars Bengal and Cypress were dried to a moisture content of ≈12% by three drying regimes: low temperature (T 20°C, RH 50%), medium temperature (T 40°C, RH 12%), and high temperature (T 60, RH 17%). Head rice grains were processed into flour and starch and evaluated for pasting characteristics with a Brabender Viscoamylograph, thermal properties with differential scanning calorimetry, starch molecular‐size distribution with high‐performance size‐exclusion chromatography (HPSEC), and amylopectin chain‐length distribution with high‐performance anion‐exchange chromatography with pulsed amperometric detection (HPAEC‐PAD). Lower head rice and starch yields were obtained from the batch dried at 60°C which were accompanied by an increase in total soluble solids and total carbohydrates in the pooled alkaline supernatant and wash water used in extracting the starch. Drying regime caused no apparent changes on starch molecular‐size distribution and amylopectin chain‐length distribution. Starch fine structure differences were due to cultivar. The pasting properties of flour were affected by the drying treatments while those of starch were not, suggesting that the grain components removed in the isolation of starch by alkaline‐steeping were important to the observed drying‐related changes in rice functionality.     

Physicochemical Properties of Sonicated Mung Bean,Potato, and Rice Starches

Mung bean, potato, and rice starch solutions (5%, w/w) were sonicated for up to 5 min after heating, and their physicochemical properties were investigated. Alkaline viscosities, including the apparent and inherent viscosities of starches, decreased. The residues of the swollen starch granules after pasting and centrifugation were also reduced prominently by sonication. Average degree of polymerization did not change with sonication. The starch paste became more transparent, and the hot paste viscosity measured at 70°C decreased remarkably. Results indicate that changes in the physicochemical properties of starch were induced by the disruption of swollen granules rather than the breakage of glucosidic linkages with sonication.     

Fractionation of High-Amylose Maize Starches by Differential Alcohol Precipitation and Chromatography of the Fractions

Three high-amylose maize starches (HAS) and a common corn starch (CCS) were subjected to differential alcohol precipitation using isoamyl alcohol and 1-butanol to obtain fractions designated as amylose (AM), amylopectin (AP), and intermediate material (IM). For each starch, IM had a blue value and an iodine binding wavelength maximum (λ_max) between the λ_max of the respective AM and AP. Size-exclusion chromatography (SEC) showed similarities in the AM from CCS and HAS. HAS AP had higher blue values and iodine binding λ_max values than CCS AP. SEC of the intact HAS AP and IM both showed large proportions of material eluting after the void volume (45–85%) when compared to CCS AP and IM. Chain length (CL) distributions of debranched AP and IM indicated that these fractions from each starch were highly branched, and that AP had a shorter average chain length than IM. Consequently, the differential precipitation behavior of the HAS AP and IM appears dependent on general branching structure rather than size. We conclude that in both CCS and HAS, AP and IM are subsets of the branched molecules with AP as the predominant fraction. For HAS, AP and IM include molecules of a size typical for AM and contain a higher proportion of chains that are longer than those of CCS AP. Differential alcohol precipitation is a useful method of separating amylose, amylopectin, and intermediate material from HAS.     

Starch-Lipid Interactions in Common,Waxy, ae du,and ae su2 Maize Starches Examined by Differential Scanning Calorimetry

Four maize genotypes (common, waxy, ae du, and ae su2) were examined by differential scanning calorimetry (DSC) in the presence of four surfactants (sodium dodecyl sulfate [SDS], dodecyltrimethylammonium bromide [DOTAB], sodium hexadecyl sulfate [SHS], 1-monolauroyl-rac-glycerol [ML]) to characterize the starch-lipid complexes produced and provide evidence of differences in starch structure. The ionic surfactants with a C₁₂ hydrocarbon tail reduced the gelatinization onset temperature, a phenomenon that does not occur typically with neutral surfactants or with surfactants with longer hydrocarbon tails. Subtracting the DSC curves, the exotherm we suspected was caused by starch-lipid complexation, which occurs concomitantly with the gelatinization endotherm, was identified and provided evidence of the existence of amylopectin-lipid interactions. Apparent starch amylose content correlated well with enthalpies of amylose-lipid complexes. Complexes formed from DOTAB produced DSC endotherms that were broad and shallow and that shifted to lower temperatures as the DOTAB concentration increased. This was in contrast to other surfactants that normally produce amylose-lipid complex endotherms at temperatures independent of surfactant concentration.     

Structures of Four Waxy Rice Starches in Relation to Thermal,Pasting, and Textural Properties

Waxy rice starches from three japonica cultivars (Taichung Waxy 1 [TCW1], Taichung Waxy 70 [TCW70], Tachimemochi) and one indica cultivar (Tainung Sen Waxy 2 [TNSW2]) were characterized for chemical and physicochemical properties. The amylopectin structures were different for the four waxy rice starches in terms of degree of polymerization (DP), average chain length (CL), exterior chain lengths (ECL), and distribution of chains, indicating the existence of varietal differences. The order of swelling power was TCW1 > TCW70 > TNSW2 > Tachimemochi; the order of water solubility index was TCW70 > TNSW2 > Tachimemochi > TCW1. The low water solubility index of TCW1 might be ascribed to a high DP. All starches shared similar gelatinization temperatures and enthalpies but showed distinct retrogradation patterns. TNSW2 showed the highest retrogradation rate, followed by TCW2, Tachimemochi, and TCW70. TCW70 exhibited the highest overall pasting viscosity, followed by TNSW2, TCW1, and Tachimemochi. The hardness of waxy rice starch pastes from a Brabender amyloviscograph increased rapidly after storage at 5°C for one day and remained the same or slightly increased after seven days of storage, whereas the opposite trend was observed for adhesiveness. The lower degree of retrogradation of TCW70 was probably a result of a larger amount of A chain and a shorter ECL. The changes in hardness correlated with the amount of A and B1 chains. The texture attributes of waxy rice starch pastes were significantly affected by amylopectin retrogradation during storage.     

高效液相色谱-串联质谱法测定水稻植株和田水中盐酸吗啉胍消解动态

2011—2012年在黑龙江肇东、河南祝楼、江苏句容三地通过田间试验,研究了盐酸吗啉胍在水稻植株和田水中的消解动态。水稻植株和田水采用UPLC-MS/MS正离子扫描测定残留的盐酸吗啉胍。结果表明,水稻植株和田水的3种添加浓度(0.005、0.05、0.5 mg·kg-1)平均回收率分别为92.50%~109.20%和86.40%~107.20%,相对标准偏差分别为6.10%~6.90%和0.73%~3.10%。本方法在植株和田水中的最低检出浓度为0.005mg·kg-1。从消解动力学方程可知,盐酸吗啉胍在水稻植株及田水中的消解半衰期分别为1.2~4.7、1.0~3.5 d。从结果判断盐酸吗啉胍属较易降解农药。     

Properties and Structures of Flours and Starches from Whole,Broken, and Yellowed Rice Kernels in a Model Study

The objective of this study was to compare the structure and properties of flours and starches from whole, broken, and yellowed rice kernels that were broken or discolored in the laboratory. Physicochemical properties including pasting, gelling, thermal properties, and X‐ray diffraction patterns were determined. Structure was elucidated using high‐performance size‐exclusion chromatography (HPSEC) and high‐performance anion‐exchange chromatography with pulsed amperometric detection (HPAEC‐PAD). The yellowed rice kernels contained a slightly higher protein content and produced a significantly lower starch yield than did the whole or broken rice kernels. Flour from the yellowed rice kernels had a significantly higher pasting temperature, higher Brabender viscosities, increased damaged starch content, reduced amylose content, and increased gelatinization temperature and enthalpy compared with flours from the whole or the broken rice kernels. However, all starches showed similar pasting, gelling, thermal properties, and X‐ray diffraction patterns, and no structural differences could be detected among different starches by HPSEC and HPAEC‐PAD. α‐Amylase may be responsible for the decreased amylopectin fraction, decreased apparent amylose content, and increased amounts of low molecular weight saccharides in the yellowed rice flour. The increased amount of reducing sugars from starch hydrolysis promoted the interaction between starch and protein. The alkaline‐soluble fraction during starch isolation is presumed to contribute to the difference in pasting, gelling, and thermal properties among whole, broken, and yellowed rice flours.     

Starch Damage and Pasting Properties of Rice Flours Produced by Dry Jet Grinding

Milling method and particle size affect some properties of rice flour. To prepare ultra‐fine rice flour of <30 μm, hammer and dry jet grinding methods were examined and the effect of particle size on starch damage and pasting properties of the flour were elucidated. A jet mill could make finer flour (<10 μm mean size) with a narrower particle size distribution than a hammer mill could. Starch damage increased dramatically at a mean size of <10 μm. Particles of a similar size (<60 μm) had different levels of starch damage between mills. Not only the particle size, but also the milling method affected the level of damaged starch. Flour samples of ≥45 μm mean size had similar viscosity curves, but samples of <20 μm had different curves. Peak viscosity and final viscosity decreased sharply at <10 μm. Setback viscosity for particles of 3 μm from both brown rice and white rice were higher than the peak viscosity. Stability to heat and shearing stress were decreased for <20 μm flours as the breakdown viscosities decreased. Starch damage and pasting properties of flour ground from the nonwaxy japonica cultivar Koshihikari changed dramatically at a mean size of <10 μm.     

Distribution of Granule Channels,Protein, and Phospholipid in Triticale and Corn Starches as Revealed by Confocal Laser Scanning Microscopy

The morphology and microstructure of starch granules from two cultivars of triticale and from normal corn were characterized using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Compared to numerous pores distributed randomly on the surfaces of corn starch granules, markedly fewer pores were observed on the surfaces of starch granules isolated from Pronghorn triticale, and even fewer on the surfaces of starch granules isolated from Ultima triticale. CLSM with fluorescence staining revealed that starch‐associated protein was predominately distributed on the granule surface and in the internal channels of both triticale and corn starches. However, after triticale starch was treated with SDS or SO₂, the radially oriented, protein‐filled internal channels of the granules were observed more frequently and extended to the central region of granules. Phospholipid was located mainly on the granule surface but also in channels and throughout granules in triticale starches, whereas in corn starch granules, it was mainly in the channels. The amount of protein and phospholipid in chemically and protease‐treated starches varied with starch source and treatment conditions. In treated triticale starches, the nitrogen content was positively correlated with the phosphorus content, indicating a close association between protein and phospholipid within starch granules. Starch‐associated protein and phospholipid may play an important role in maintaining the structural stability of both the granule surface and the internal channels.     

Physicochemical Properties of Rice Endosperm Proteins Extracted by Chemical and Enzymatic Methods

Rice proteins are nutritional, hypoallergenic, and healthy for human consumption. Efficient extraction with approved food‐grade enzymes and chemicals are essential for commercial production and application of rice protein as a functional ingredient. Rice endosperm proteins were isolated by alkali, salt, and enzymatic methods and evaluated for extractability and physicochemical properties. Alkali (RP_A) and salt (RP_S) methods extracted 86.9 and 87.3% of proteins with 65.9 and 58.9% yield, respectively. The enzymatic methods with Termamyl (RP_ET) and amylase S (RP_EA) extracted 85.8 and 81.0% proteins with 85.2 and 86.2% yield, respectively. Enthalpy values of RP_A (1.79 J/g), RP_S (1.22 J/g), RP_ET (nondetectable), and RP_EA (0.17 J/g), determined by differential scanning calorimetry, demonstrated that the varying level of denaturation of proteins depends on the method of extraction. Surface hydrophobicity data supported this observation. Alkali‐ and salt‐extracted proteins had higher solubility and emulsifying properties than those of enzyme‐extracted proteins. Comparatively, more favorable protein composition, lower surface hydrophobicity, higher solubility, and a lower degree of thermal denaturation of alkali‐ and salt‐extracted proteins contributed to higher emulsifying and foaming properties than those of enzyme‐extracted proteins; therefore, alkali‐ and salt‐extracted proteins can have enhanced functional use and a potential starting material for preparing tailored rice protein isolates.     

Wheat Flour Proteins as Affected by Transglutaminase and Glucose Oxidase

Enzymes are good tool to modify wheat proteins by creating new bonds between the protein chains. In this study, the effect of the addition of glucose oxidase (GO) and transglutaminase (TG) on the wheat flour proteins is presented. The modification of wheat proteins was determined by analyzing the changes in gluten quality, alveograph parameters, and protein modifications. The amount of wet gluten increased with the addition of GO and TG, but the gluten quality was not improved in any case. Regarding the alveograph parameters, the effect of GO was readily evident obtaining wheat dough with higher tenacity and lower extensibility than the control, while TG led to doughs with lower tenacity and that were also less extensible. The protein modifications were characterized by free‐zone capillary electrophoresis (FZCE). FZCE data indicated that TG polymerizes mainly glutenins and, of those, the high molecular weight glutenin subunits were the most affected.     

Cadmium and Nutrient Heavy Metals Uptake by Rice,Barley, and Spinach as Affected by Four Ammonium Salts

This experiment was conducted to investigate the influence of ammonium salts on the uptake of cadmium (Cd) and nutritional heavy metals (copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe)) by rice, barley, and spinach. These plants were grown in Cd, Cu, and Zn contaminated entisol (ES) or andisol (AS). The following ammonium salts were used: ammonium nitrate (NH₄NO₃), ammonium sulfate ((NH₄)₂SO₄), ammonium chloride (NH₄Cl), and ammonium dihydrogen phosphate (NH₄H₂PO₄). In ES, the Cd concentrations in three plant shoots were higher with NH₄Cl than with the other salts. The concentrations of Cd in soil solutions collected from ES were higher with NH₄Cl. Thus, the increase of Cd uptake by three plants with NH₄Cl treatment would be caused by the increased concentration of Cd in the soil solution. In contrast, in AS, the concentrations of the heavy metals in the shoots of all plants were not different among NH₄ applications, with one exception, the Mn concentration in rice increased with NH₄Cl in both ES and AS.     

Rice Milling Quality,Grain Dimensions,and Starch Branching as Affected by High Night Temperatures

Important rice grain quality characteristics such as percentage of chalky rice kernels are affected by both high and low night temperatures and by different day and day/night temperature combinations. High nighttime temperatures have also been suspected of reducing rice milling quality including head rice yields. Experiments to confirm or refute this have not been reported. A controlled climate experiment was conducted. Conditions in the chambers were identical except between 2400 and 0500 hours (midnight and 5 am). For those times, two temperature treatments were imposed: 1) 18°C (low temperature treatment) and 2) 24°C (high temperature treatment). Two cultivars were tested: LaGrue and Cypress. The high temperature treatment reduced head rice yields compared with the low temperature treatment. Grain widths were reduced for the high temperature treatment compared with the low temperature treatment. There was no effect of temperature on grain length or thickness. Amylopectin chain lengths 13–24 were increased by the high temperature treatment by ≈1%. Future research will focus on determining whether genetic variability exists among cultivars in their head rice yield response to high temperatures. After identifying a source of resistance to high temperature effects, this characteristic can be incorporated into rice cultivars. In addition, ways to reduce this effect, including biotechnological remedies, have the potential for increasing rice yield and quality.     

Physical Characteristics,Nutritional Quality,and Antioxidant Potential of Extrudates Produced with Polished Rice and Whole Red Bean Flours

In Brazil, rice (Oryza sativa L.) and beans (Phaseolus vulgaris L.) are the basis of the population's diet, and their consumption together is a good strategy to improve protein biological value. The aim of this study was to produce extruded products with whole red bean (WRBF) and polished rice (PRF) flours and to evaluate the effects of extrusion temperature (T) and feed moisture content (FM) on technological properties and total phenolic compounds content. The extrudates were elaborated in a twin‐screw extruder following a 2² central composite rotatable design with FM (15–23%) and T (120–160°C) as independent variables. WRBF and PRF were used at a 1:3 ratio. Amino acid content and profile were evaluated in the optimum extrudate (produced at FM = 19% and T = 140°C). The total phenolic content identified in extruded products was provided by the red bean seed coat, and its quantification suggested the release of bound phenolics with the extrusion process (not temperature dependent). The extrusion of PRF and WRBF, in combination, produced extruded products of high protein quality, being complete in essential amino acids for the diets of people at least 48 months old. The results indicate that legume flours such as WRBF incorporated into rice flour can cause a positive impact on technological, nutritional, and functional quality of extrudates.     

Rice Growth and Nutrient Accumulation as Affected by Different Composts

Abstract

This study evaluated the effects of four different kinds of compost: pea–rice hull compost (PRC), cattle dung–tea compost (CTC), hog dung–rice hull compost (HDR), and hog dung–sawdust compost (HDS). These types of compost differ in nitrogen composition and in the dry matter yield and nutrient accumulation [nitrogen (N), phosphorus (P), potassium (K)], of rice plants. The rice (Oryza sativa L.) plants were planted in an Oxisol soil. Plants were cultivated in pots, which contained 3 kg of soil, mixed with the four different composts (PRC, 404 g; CTC, 395 g; HDR, and HDS, 450 g) and chemical fertilizer (CHEM) (N:P₂O₅:K₂O=120:96:72) The residual effect was studied after the crop was harvested. All treatments were replicated four times, with a randomized complete block design. The nutrient concentrations in the root, leaf sheath, leaf blade, stalk, and grain were analyzed at different growth stages. After the first crop, the dry matter yield and the amount of N, P, and K absorbed from the CTC or HDS treatments were higher than those of the other treatments, at the most active tillering stage. The growth and nutrient accumulation of rice plants given the PRC treatment were higher than those given the CHEM treatment at the heading stage or the HDR treatment at the maturity stage. In the second crop, the dry matter yield from the PRC, CTC, and HDR treatments was higher than from the other treatments. The nutrient accumulation of the rice plants was positively correlated with the dry matter yield. The residual effect of the HDS compost was the least among all four composts.     

我国水稻、小麦、玉米基肥和追肥用量及比例分析

提高肥料利用率的一个很关键的措施就是同步作物的养分需求与土壤、肥料的养分供应。本文依据农户调查数据和统计资料,详细分析了我国水稻、小麦和玉米氮磷钾基肥和追肥用量及比例,并利用施肥比面这个指标筛选分析了三大粮食作物上六个主要化肥品种作基肥和追肥的用量和比例。最后针对我国基追比现状本文提出了应综合考虑不同地区影响基追比的因素,在高肥力地区采用降低基肥的用量,加大追肥用量的氮肥后移的施肥方式;在肥料品种方面对于氮肥来说仍要保持单质氮肥的生产和应用,对于磷钾来说,应针对不同的肥料品种加大肥料复合化和专用化。     

Nitrate Reductase,Micronutrients and Upland Rice Development as Influenced by Soil pH and Nitrogen Sources

The average yield of upland rice under no-tillage system (NTS), a sustainable soil management, is lower than in conventional tillage (one plowing and two disking). One of the reasons given for this drop in crop grain yield would be the low-nitrate assimilation capacity of rice seedlings, due to the low activity of the nitrate reductase (NR) enzyme in the early development phase. A greenhouse experiment was conducted to evaluate the effects of the soil acidic and nitrogen source in the micronutrient concentrations, NR activity and grain yield of upland rice growing under NTS. The soil used in the experiment was an Oxisol. The experimental design was completely randomized in a factorial 3 × 4. Treatments consisted of three levels of soil acidity (high, medium, and low) combined with four nitrogen sources (nitrate, ammonium, ammonium + nitrification inhibitor, and control – without N fertilization). The reduction of soil acidity reduced the concentration of zinc and manganese in rice plants. Generally, the activity of the NR enzyme was higher in plants grown in soils with low acidity and fertilized with calcium nitrate. There was a greater response in growth and yield in rice plants grown in soils with high acidity. Under medium acidity, rice plants grown with ammonium sulfate were more productive (no differences were detected with the addition of the nitrification inhibitor).     

Iron Availability as Affected by Soil Moisture in Intercropped Peanut and Maize

Abstract

Pot and rhizobox experiments were carried out to investigate the iron availability in intercropped peanut and maize as affected by soil moisture. Results from pot experiment showed that the root growth of peanuts were significantly inhibited at 25% soil water content compared to those at 15% soil water content. The chlorophyll content in the new leaves of intercropped peanut decreased and leaves became chlorotic at 25% soil water content. There were no significant differences in the active iron concentration in new leaves of peanut between 15% and 25% soil water content. The soil pH were higher in peanut rhizosphere than in bulk soil at the early, middle, and harvest stages for both 15% and 25% soil water content. The soil bicarbonate content was also higher in peanut rhizosphere than in bulk soil for both 15% and 25% soil water content. There was significant difference in soil bicarbonate of peanut rhizosphere between 15% and 25% soil water content at the harvest stage. The available iron content in both rhizosphere soil and bulk soil were lower than 3.5 mg kg^?1 in all growth stages at both 15% and 25% soil water content. Results from rhizobox experiment showed that citric acid, maleic acid, and fumaric acid in exudates of peanuts significantly increased at 25% soil water content compared to that at 15% soil water content. The apoplastic iron content of peanut roots decreased by 0.216 and 0.409 µmol g^?1 fresh weight^?1 (FW) from the 28th growth day to 42nd growth day at 25% and 15% soil water content, respectively. The mobilizing ability of apoplastic iron in intercropped peanuts at 15% soil water content was 20.1% higher compared to that at 25% soil water content. It is concluded that improvement of iron nutrition of peanuts with intercropping with maize could be affected by soil moisture condition.