A comparative survey of recent results on humic-like fractions in organic amendments and effects on native soil humic substances

The main scope of the wide use of organic amendments of various origin and nature in modern agriculture is to increase and/or restore the organic matter content in organically poor or depleted soils in order to maintain and/or increase crop production and reduce soil exposure to degradation, erosion, desertification and pollution. The agronomically efficient and environmentally safe use of any organic amendment requires, however, an adequate control not only of the chemical quality of the humic substance (HS)-like fractions contained, which is an important indicator of the maturity and stability achieved by organic matter in the amendment, but also of the effects that these HS may have on native soil HS. In this review, the most recent results obtained on this topic by the research groups operating in Bari, Italy, and in Madrid, Spain, are discussed comparatively with results recently published by other research groups. Overall, HS-like components of organic amendments are characterized by higher aliphatic character and molecular heterogeneity, lower contents of O, acidic functional groups and organic free radicals, and lower degrees of aromatic ring polycondensation, polymerization and humification than native soil HS. These differences are less evident for composted materials. The composition, structure and functionalities of HS in amended soils may be affected in different ways and at various extents on dependence of the nature, origin and rate of amendment. In general, these properties are intermediate between those of the unamended soil HS and the HS-like fractions in the amendment, but generally resemble more the former than the latter, especially with increasing time after amendment application.     

超声联合滚揉腌制对鸡胸肉品质的影响研究

为了改善淘汰蛋鸡鸡胸肉的品质,探明超声联合滚揉腌制对鸡胸肉保水性、嫩度和挥发性风味成分的影响。本研究基于不同腌制工艺下鸡胸肉腌制液的吸收率和肉品质(蒸煮损失、离心损失、剪切力)的差异,通过低场核磁共振、组织切片和顶空固相微萃取气相质谱联用(HS-SPME-GC-MS)技术分析了鸡胸肉品质发生变化的原因。结果表明,滚揉腌制和超声联合滚揉腌制均加快了腌制速率,提高了鸡胸肉的保水性和嫩度,原因可能是滚揉和超声波的机械作用促进了水分的迁移和均匀分布,破坏了肌纤维结构,并且超声和滚揉具有协同效果。此外,采用滚揉腌制和超声联合滚揉腌制对鸡胸肉挥发性风味成分的种类及含量都有一定影响。本研究结果为改良鸡肉品质、开发低磷酸盐含量的鸡肉制品提供了理论参考。     

Characterization of DAX‐8 adsorbed soil fulvic acid fractions by various types of analyses

We investigated the optical absorption properties (A ₄₀₀/C and A ₆₀₀/C values), elemental composition, weight-averaged molecular weight (Mw), and liquid-state carbon-13 (¹³C) nuclear magnetic resonance (NMR) spectroscopy of DAX-8 adsorbed fulvic acid fractions (DAX-8 FAs) in various soils (n?=?36) to establish the general trends in their chemical characteristics. We also compared our results with those of humic acids (HAs) obtained from the same soils used in this study and other published data to discuss the differences between them. Our results clearly indicate that DAX-8 FAs with high carboxyl C content have small Mw and low hydrogen to carbon (H/C) ratio. In addition, DAX-8 FAs with high carbonyl C and alkyl C content have high A ₄₀₀/C values and H/C ratios, respectively. These results strongly suggest that DAX-8 FAs with high aliphatic chemical properties have low carboxyl C content, large Mw and high H/C ratio. There are significant differences in chemical characteristics among the various soil types in almost all data; e.g., DAX-8 FAs from Podzols showed significantly higher A ₄₀₀/C values, larger Mw, higher carbonyl C and O-aryl C content than those obtained from Andosols. However, these two C functional groups are relatively low values in the total C content among all soil types, suggesting that DAX-8 FAs may exhibit only small differences in chemical properties among the various soil types. The comparison with published data regarding soil HAs shows that DAX-8 FAs are characterized by smaller Mw; lower C, H, and nitrogen (N); higher oxygen (O) content; higher O/C; lower O/H ratios; higher carboxyl C content; and lower aryl C content in total C.     

Carbon and nitrogen forms in soil organic matter influenced by incorporated wheat and corn residues

We have investigated molecular-scale changes in soil organic matter (SOM) as incorporated wheat and corn residues decompose and whether those changes are correlated with soil nitrogen forms. The ‘initial litter quality hypothesis’ that compositional variations in plant residues may persist during decomposition of these residues as they are transformed to SOM was tested. We studied soils in 6-year field experiments of a double-cropped corn–wheat rotation system designed with the following treatments: no crop residue and no chemical fertilizer, chemical fertilizer alone, wheat straw + chemical fertilizer, corn stover + chemical fertilizer, and corn plus wheat residue + chemical fertilizer. Organic carbon and nitrogen forms were assessed, and SOM chemical structures were examined by Fourier transform infrared and solid-state nuclear magnetic resonance spectroscopy. We found that concentrations of organic-N in corn residues plus fertilizer treatment were significantly larger than those in wheat straw plus fertilizer treatment. In addition, concentrations of amide groups and NCH in SOM with corn residue treatment were larger than those in SOM with wheat residue treatment. Incorporation of both corn and wheat residues led to an increase in carbohydrate-derived components of SOM. Compared with the check treatment, aromaticity, alkyl C/O-alkyl C, and hydrophobicity/hydrophilicity indices of the SOM were lower with addition of residue. Aromaticity was greater in corn residue treatment than in wheat residue treatment. This study provides support for the hypothesis that the variation in chemical composition of SOM reflected the incorporation of distinct chemical structures in wheat and corn straw residues.     

基于低场核磁的稻谷储藏指标快速测定初探

本研究用国标方法和低场核磁仪器分别检测3种储藏年份和2个品种籼稻的含水量、粗脂肪含量、直链淀粉、发芽率等理化指标和横向弛豫曲线,简单分析弛豫曲线的变化规律,并采用偏最小二乘法将理化指标和核磁数据进行关联.结果表明,稻谷的横向弛豫强度衰减速度很快,弛豫时间段0～300ms为区分稻谷样品的重要特征信号区域;回归模型结果初步表明使用低场核磁能够较好地预测稻谷储藏指标,如含水量、脂肪含量、直链淀粉和发芽率等.     

代谢组学及其相关技术与应用研究

代谢组学又称代谢物组学,是研究机体代谢产物谱变化的一种新的系统方法。它借助高通量、高灵敏度与高精确度的现代分析技术,分析细胞、组织和其它生物样本如血液、尿液、唾液和体液中内源性代谢物整体组成并通过其复杂的、动态的变化,从整体上反应代谢物图。     

Carbon and Nitrogen Mineralization and Humus Composition Following Municipal Solid Waste Compost Addition to Laterite Soils under Continuous Cassava Cultivation

A glasshouse incubation experiment was conducted to study the carbon (C) and nitrogen (N) mineralization of municipal solid waste compost (MSWC) added at differential rates to a laterite soil where cassava has been continuously cultivated for the past 10 years. The rate of C mineralization from added substrates increased with increasing rates of addition of MSWC. Available N significantly increased with increase in the rate of application of MSWC. There was a decreasing trend in E₄₆₅/E₆₆₅ ratio of humic acid as we increased the rate of application of MSWC from 2.5 to 20 t ha^?1. The Cross Polarization Magic Angle Spinning (CPMAS) ¹³C NMR spectral analysis revealed that there are differences in the rate of humification of added MSWC, and application of MSWC at 15 t ha^?1 resulted in least humification with the greatest alkyl C, lowest aromatic C, and greater O-alkyl C content. The decomposition rate (R) was found to be greater for this treatment. The residual C in soil was found to increase over time coincident with greater rates of MSWC application, indicating increased C stabilization, which could improve soil quality.     

Synthesis,Structural and Pharmacological Characterizations of CIC,a Novel α-Conotoxin with an Extended N-Terminal Tail

Cone snails are venomous marine predators that rely on fast-acting venom to subdue their prey and defend against aggressors. The conotoxins produced in the venom gland are small disulfide-rich peptides with high affinity and selectivity for their pharmacological targets. A dominant group comprises α-conotoxins, targeting nicotinic acetylcholine receptors. Here, we report on the synthesis, structure determination and biological activity of a novel α-conotoxin, CIC, found in the predatory venom of the piscivorous species Conus catus and its truncated mutant Δ-CIC. CIC is a 4/7 α-conotoxin with an unusual extended N-terminal tail. High-resolution NMR spectroscopy shows a major influence of the N-terminal tail on the apparent rigidity of the three-dimensional structure of CIC compared to the more flexible Δ-CIC. Surprisingly, this effect on the structure does not alter the biological activity, since both peptides selectively inhibit α3β2 and α6/α3β2β3 nAChRs with almost identical sub- to low micromolar inhibition constants. Our results suggest that the N-terminal part of α-conotoxins can accommodate chemical modifications without affecting their pharmacology.