Use of LCA indicators to assess Iranian rapeseed production systems with different residue management practices

In this study the environmental profile of Iranian rapeseed cultivation was analysed with a Life Cycle Assessment (LCA) approach, in order to identify the hot spots of the system. Also, in order to apply environmental indicators for agricultural decision making purposes, the environmental burden of different residue management practices were compared. Primary data were collected from 150 rapeseed farms from the Iranian Mazandaran province. The system considers a cradle-to-farm gate boundary, and the functional unit was regarded as being one Mg of rapeseed production. The LCA results indicate that the global warming potential amounts to 1181.6 kg CO_2eq Mg⁻¹. Also, the acidification and eutrophication potentials were found to be 23.3 kg SO_2eq Mg⁻¹ and 18 kg PO₄³_eq Mg⁻¹, respectively. The results also reveal that environmental emissions of crop production were significantly affected by residue management practices. Specifically, rapeseed residue removal from the field is the most environmentally-friendly practice. This is followed by a scenario involving residue incorporation in the soil. The practice of burning such residue entails the highest environmental emissions. In conclusion, reducing the consumption of chemical fertilisers, especially nitrogen based ones, is important for decreasing the environmental footprints in the area. Furthermore, avoiding crop residue burning and developing rapeseed-bean rotation are favourable management strategies for establishing more environmentally-friendly rapeseed production systems in the region.     

Penicillin-binding protein 3 of Streptococcus pneumoniae and its application in screening of β-lactams in milk

The soluble form of penicillin-binding protein 3 (sPBP3^∗) from Streptococcus pneumoniae was expressed in Escherichia coli as a six-histidine fusion protein. The protein was purified and used to develop a microplate assay in direct competitive format for the detection of penicillins and cephalosporins in milk. The assay was based on competitive inhibition of the binding of horseradish peroxidase-labeled ampicillin (HRP–Amp) to the sPBP3^∗ by free β-lactam antibiotics in milk. Under optimized conditions, most of the β-lactam antibiotics (11 penicillins and 16 cephalosporins) could be detected at concentrations corresponding to the maximum residue limits (MRLs) set by the European Union. Analysis of spiked milk samples showed that acceptable recoveries ranged from 74.06 to 106.31% in skimmed milk and from 63.97 to 107.26% in whole milk, with coefficients of variation (CVs) less than 16%. With the high sensitivity and wide-range affinities to penicillins and cephalosporins, the developed assay based on sPBP3^∗ exhibited the potential to be a screening assay for fast detection of β-lactam antibiotics in milk.     

Properties of ACE inhibitory peptide prepared from protein in green tea residue and evaluation of its anti-hypertensive activity

Green tea contains active ingredients which are beneficial for health. While numerous studies have been conducted on the components extracted from green tea, few studies have investigated the active ingredients in tea residue. In this study, proteins were extracted from green tea residue via an optimised alkaline extraction combined with enzymatic hydrolysis, of which, an acidic protease was selected to prepare an enzymatic hydrolysate because of its high angiotensin converting enzyme (ACE) inhibitory activity. The composition characteristics of extracted green tea proteolysis products were elucidated, including amino acid composition, molecular weight distribution and possible amino acid sequences. In addition, the protein hydrolysate had anti-digestive properties, maintained its activity of inhibiting ACE enzyme at different temperatures, pH and metal ions, and exhibited antihypertensive activity in animals. In conclusion, the optimised alkaline extraction and enzymatic hydrolysis conditions of a ACE inhibitory peptide from green tea residue is an optimal extraction method to maintain its antihypertensive activity, providing the basis for the clinical application of green tea for blood pressure reduction.     

A residue-level investigation of the equilibrium unfolding of the C2A domain of synaptotagmin 1

Fibroblast growth factor (FGF) 1 is known to be released in response to cellular stress conditions through formation of a multi-protein complex with synaptotagmin 1 and S100A13. In this study, we characterized the denaturant-induced unfolding of synaptotagmin 1, C2A domain in a residue-specific manner by NMR spectroscopy. The amide protons of 30 residues distributed throughout the 3D structure of the whole protein could be followed in a series of ¹H-¹⁵N HSQC spectra recorded from 0 to 8 M urea under equilibrium conditions. The midpoint for the urea-induced unfolding obtained from NMR coincides with those obtained from steady state fluorescence and CD spectroscopy, revealing that the protein unfolds via a two-state mechanism without accumulating stable intermediates. The thermodynamic parameter obtained from the denaturation curve illustrates the cooperative unfolding of the C2A domain. The implications of C2A domain folding in relation to the release of FGF-1 from the multi-protein complex were discussed.     

Alpha7 Helix Plays an Important Role in the Conformational Stability of PTP1B

Abstract

The C-terminus of Protein Tyrosine Phosphatase 1B (PTP1B) includes an α-helix (α7), which forms an allosteric binding site 20 Å away from the active site. This helix is specific to PTP1B and its truncation decreases the catalytic activity significantly. Here, molecular dynamics (MD) simulations in the presence and absence of α7 were performed to investigate the role played by α7. The highly mobile α7 was found to maintain its contacts with loop 11 (L11)- α3 helix throughout the simulations. The interactions of Tyr152 on L11, Tyr176, Thr177 on the catalytically important WPD loop and Ser190 on α3 are important for the conformational stability and the concerted motions of the regions surrounding the WPD loop. In the absence of α7, L11 and WPD loop move away from their crystal structure conformations, resulting in the loss of the interactions in this region, and a decrease in the residue displacement correlations in the vicinity of WPD loop. Therefore, we suggest that one of the functionally important roles of α7 may be to limit the L11 and α3 motions, and, facilitate the WPD loop motions. Truncation of α7 in PTP1B is found to affect distant regions as well, such as the substrate recognition site and the phosphate binding-loop (P-loop), changing the conformations of these regions significantly. Our results show that the PTP1B specific α7 is important for the conformation and dynamics of the WPD loop, and also may play a role in ligand binding.     

Inactivation of Rabbit Liver Carbonyl Reductase by Phenylglyoxal and 2,3,4-Trinitrobenzenesulfonate Sodium

The chemical modifications of rabbit liver carbonyl reductase (RLCR) with phenylglyoxal (PGO) and 2,3,4-trinitrobenzenesulfonate sodium (TNBS), which are respective chemical modifiers of arginine and lysine residues, were examined. RLCR was rapidly inactivated by these modifiers. Kinetic data for the inactivation demonstrated that each one of arginine and lysine residues is essential for catalytic activity of the enzyme. Furthermore, based on the protective effects of NADP +, NAD + and their constituents against the inactivation of RLCR by PGO and TNBS, we propose the possibility that the functional arginine and lysine residues are located in the coenzyme-binding domain of RLCR and interact with the 2′-phosphate group of NADPH.     

菊花病虫害综合防治研究

系统调查鉴定了菊花病毒病、霜霉病、叶斑病、叶面害虫、蚜虫天敌种类及其流行规律,研究了组培脱毒苗、地膜覆盖移栽、与高秆作物套作、摘顶稍、利用昆虫天敌及化学防治等综合治理效果.测定了农药残留量.结果表明,菊花组培苗脱毒率在60%左右,脱毒苗增产50%以上,叶枯病、霜霉病病叶率下降28%～30%,虫口密度下降40%,在收菊花前1个月使用拟菊酯杀虫剂,农药残留量低于允许值,不会对菊花和环境造成污染.     

枯草杆菌蛋白酶嗜热性改造单突变效果评判方法研究

对蛋白质进行嗜热性改造是蛋白质工程的主要问题之一,残基突变方法被广泛运用于其中。本文以枯草杆菌蛋白酶（SUBTILISIN BPN＇）为研究对象,旨在建立评判嗜热性改造效果的方法,选取了有可靠实验资料的9个突变点,运用分子动力学模拟方法,在四种不同模拟条件下,对其中的6个突变体和1个野生型蛋白进行了多种参量的对比分析,提取4个特征有效参量,建立了蛋白酶嗜热性改造单突变效果评判方法;利用该方法对其它3个突变效果进行评判,评判结果与实验资料完全吻合,证明该方法可用于枯草杆菌蛋白酶嗜热性改造单突变效果的评判。     

Dynamics of DDB2-DDB1 complex under different naturally-occurring mutants in Xeroderma Pigmentosum disease

Background

Xeroderma Pigmentosum (XP) is a disease caused by mutations in the nucleotide excision repair (NER) pathway. Patients with XP exhibit a high propensity to skin cancers and some subtypes of XP can even present neurological impairments. During NER, DDB2 (XPE), in complex with DDB1 (DDB-Complex), performs the DNA lesion recognition. However, not much is known about how mutations found in XP patients affect the DDB2 structure and complex assembly. Thus, we searched for structural evidence associated with the role of three naturally occurring mutations found in XPE patients: R273H, K244E, and L350P.

Simulating the effects of N availability, straw particle size and location in soil on C and N mineralization

Predicting the C and N mineralization of straw added to soil is important for forecasting subsequent soil N availability during and between crop growth cycles. The decomposition module of the STICS model, parameterized under optimal conditions, was used to predict straw decomposition in sub-optimal conditions, i.e. when contact between soil and residue was poor (due to large size residues or surface placement) or when mineral N availability was restricted. The data used in the simulations were obtained from published studies of effects of residue size, location and N availability on C and N mineralization from straw under controlled laboratory conditions. We selected studies in which the dynamics of C and N mineralization were measured simultaneously. The dynamics of straw mineralization could be well predicted by the model under optimal conditions with standard parameter values as derived from measured C/N ratios of the residues, but not under sub-optimal conditions which required a new parameterization. A good fit could be obtained on these treatments by a marked reduction in the rate constants of residue and microbial biomass decomposition and a marked increase in the microbial biomass C/N ratio. Our results show the need to include in decomposition models routines for simulating effects of spatial heterogeneity of residue distribution, different particle sizes and limiting N availability.