蛋鸡对叶黄素和叶黄素酯生物利用率的比较

将40只产蛋后期海兰灰商品蛋鸡,随机分为2个组,用低叶黄素饲粮耗空2周后,分别饲喂在基础日粮中添加叶黄素酯和游离叶黄素的叶黄素强化日粮,两组均含有效叶黄素15 mg/kg.结果显示,蛋鸡采食叶黄素后,血浆中叶黄素含量提高显著(P＜0.05),但两组在第3、7和12 d时血浆叶黄素含量差异不显著(P＞0.05).     

Influence of Urea and Dimethyl Sulfoxide on K-Peptide Fibrillation

Protein fibrillation leads to formation of amyloids—linear aggregates that are hallmarks of many serious diseases, including Alzheimer’s and Parkinson’s diseases. In this work, we investigate the fibrillation of a short peptide (K-peptide) from the amyloidogenic core of hen egg white lysozyme in the presence of dimethyl sulfoxide or urea. During the studies, a variety of spectroscopic methods were used: fluorescence spectroscopy and the Thioflavin T assay, circular dichroism, Fourier-transform infrared spectroscopy, optical density measurements, dynamic light scattering and intrinsic fluorescence. Additionally, the presence of amyloids was confirmed by atomic force microscopy. The obtained results show that the K-peptide is highly prone to form fibrillar aggregates. The measurements also confirm the weak impact of dimethyl sulfoxide on peptide fibrillation and distinct influence of urea. We believe that the K-peptide has higher amyloidogenic propensity than the whole protein, i.e., hen egg white lysozyme, most likely due to the lack of the first step of amyloidogenesis—partial unfolding of the native structure. Urea influences the second step of K-peptide amyloidogenesis, i.e., folding into amyloids.     

Effect of an organic and conventional rearing system on the mineral content of hen eggs

In this study, the effect on mineral content of eggs from organic and conventional-housing systems was investigated. For this, random samples of 12 eggs were collected in both housing systems. Egg shells and edible portions were analysed for ash, Ca, P, Mg, Fe, Zn and Cu contents.The P and Zn contents of the edible egg portion were lower in the organic eggs than in conventional eggs. Mg content of the eggshell was higher in organic eggs while Zn content showed a marked decrease. As far as Ca, Fe and Cu values were concerned, these did not differ between the eggs from organic and conventional systems.The results showed considerable differences in mineral content between the eggs from the hens reared in organic and conventional systems.     

A sulfadimidine model to evaluate pharmacokinetics and residues at various concentrations in laying hen

Low level intake of drugs from the ingestion of contaminated feed may lead to residue problems in food animals. Sulfadimidine (SDD) was used as a model to determine the residue risk at various doses in laying hens. The drug was administered as a single intravenous injection (100 mg kg^-1 body weight, BW), as a single oral dose (100, 30, 10, 3, 1 mg kg^-1 BW) and via medicated feed for 7 consecutive days (30, 10, 3 mg kg^-1 BW). Drug levels were determined with HPLC-UV for plasma, yolk and albumen. Pharmacokinetic values, which were calculated using a first-order one-compartment model, residue levels and transfer rates into the eggs were found to be dose-dependent. Even low doses of 3 and 1 mg kg^-1 BW resulted in measurable residues in yolk and albumen 1 day after a single oral administration. After ingestion of medicated feed at 3 mg kg^-1 BW, mean drug levels at 0.14 ± 0.01 µg g^-1 were found in albumen and at 0.09 ± 0.01 µg ml^-1 in plasma. Generally, the residue levels in albumen and plasma were higher than in yolk. These findings demonstrate a residue risk for the consumer even after low level intake of drugs.     

超高效液相色谱-串联质谱法测定鸡肉、鸡蛋中氟苯尼考和氟苯尼考胺残留

目的建立超高效液相色谱-串联质谱准确测定鸡肉、鸡蛋中氟苯尼考和氟苯尼考胺残留的分析方法。方法鸡肉和鸡蛋样品加入D5-氯霉素内标,经氨化乙酸乙酯混合溶液超声离心提取,提取液减压蒸馏浓缩后,C18固相萃取柱净化处理,采用超高效液相色谱-串联质谱法对氟苯尼考和氟苯尼考胺同时进行检测。结果氟苯尼考线性范围为0.2～20μg/L,检出限为1.0μg/kg,定量限为3.0μg/kg,方法回收率为88.0%～108.0%,相对标准偏差为4.7%～6.4%;氟苯尼考胺线性范围为0.2～20μg/L,检出限为1.0μg/kg,定量限为3.0μg/kg,方法回收率为76.0%～93.1%,相对标准偏差为4.1%～7.2%。结论本方法精确、重现性好,适用于鸡肉、鸡蛋中氟苯尼考和氟苯尼考胺残留量的测定。     

Hen Egg‐White Lysozyme Crystallisation: Protein Stacking and Structure Stability Enhanced by a Tellurium(VI)‐Centred Polyoxotungstate

As synchrotron radiation becomes more intense, detectors become faster and structure‐solving software becomes more elaborate, obtaining single crystals suitable for data collection is now the bottleneck in macromolecular crystallography. Hence, there is a need for novel and advanced crystallisation agents with the ability to crystallise proteins that are otherwise challenging. Here, an Anderson–Evans‐type polyoxometalate (POM), specifically Na₆[TeW₆O₂₄] ? 22 H₂O (TEW), is employed as a crystallisation additive. Its effects on protein crystallisation are demonstrated with hen egg‐white lysozyme (HEWL), which co‐crystallises with TEW in the vicinity (or within) the liquid–liquid phase separation (LLPS) region. The X‐ray structure (PDB ID: 4PHI) determination revealed that TEW molecules are part of the crystal lattice, thus demonstrating specific binding to HEWL with electrostatic interactions and hydrogen bonds. The negatively charged TEW polyoxotungstate binds to sites with a positive electrostatic potential located between two (or more) symmetry‐related protein chains. Thus, TEW facilitates the formation of protein–protein interfaces of otherwise repulsive surfaces, and thereby the realisation of a stable crystal lattice. In addition to retaining the isomorphicity of the protein structure, the anomalous scattering of the POMs was used for macromolecular phasing. The results suggest that hexatungstotellurate(VI) has great potential as a crystallisation additive to promote both protein crystallisation and structure elucidation.     

Abscheidung hochohmiger Stäube in einem Elektrofilter mit niederfrequenter Wechselspannung

Due to the occurrence of back corona, the separation of particles with high electrical resistivity in electrostatic precipitators (ESPs) is difficult. In this case, the power consumption of the ESPs is significantly increased, and unacceptably high particulate emissions occur. Here, a novel approach for the separation of highly resistive dusts with ESPs is described. The effective electrical resistance of the dust layer can be modified by the use of low‐frequency AC voltage, which significantly improves the separation rates. The new method was tested with various highly resistive dusts in a wire‐tube ESP.     

Androgen Mediation of Conditioned Rhythmic Cloacal Sphincter Movements in Japanese Quail (Coturnix japonica).

Demonstrations of increased reproductive success due to sexual conditioning in Japanese quail (Coturnix japonica) have been reported, although the mechanisms that underlie these effects have remained elusive. One possible mechanism is conditioned rhythmic cloacal sphincter movements (RCSM). Two experiments were conducted with male quail to determine whether associations between a conditioned stimulus (CS) and a hen would result in the ability of the CS to elicit RCSM, and to explore the androgen mediation of conditioned RCSM. The results suggest that a focal CS paired with visual access to a female will elicit RCSM via a representation of the hen activated by the CS. Further, the available evidence indicates that conditioned RCSM is androgen mediated and that this learning may transfer across breeding seasons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determination of phytic acid in feeds and faeces of pigs and poultry by capillary isotachophoresis

A method for phytic acid determination in the feeds and faeces of pigs and poultry has been developed on the basis of capillary isotachophoresis. Phytic acid was extracted by 0.95 M HCl and separated from interfering compounds by iron precipitation. Complete formation of ferric phytate required 7 mol FeCl₃ mol⁻¹ phytic acid. Residual Fe³⁺ was estimated colorimetrically by the tiron reagent, and ferric phytate was dissolved in 1.5 M NaOH at 9 mol NaOH mol⁻¹ Fe precipitated. Analyses were carried out using an electrolyte system with Cl⁻ as the leading anion, bis‐tris‐propane, and 2‐morpholinoethanesulphonic acid as the terminating anion. The recovery of phytic acid (added to hen faeces) using this procedure was 962 ± 24 g kg⁻¹. The limit of determination of phytic acid was 0.3 µmol ml⁻¹ extract. The amount of phytic acid in feeds ranged from 8.3 to 10.8 g kg⁻¹ on a dry matter basis. Phytic acid P represented 112 g kg⁻¹ total P in faeces of young pigs (40–60 kg) fed a feed with supplemental phytase (490 U kg⁻¹), 153 g kg⁻¹ total P in faeces of finishing pigs and 185 g kg⁻¹ total P in faeces of non‐lactating sows. Excreta of laying hens contained 23.7 g phytic acid kg⁻¹ dry matter (362 g kg⁻¹ total P). The isotachophoretic method is sufficiently simple and reproducible to be used for routine analyses of feeds and faeces. © 2000 Society of Chemical Industry     

卵黄高磷蛋白酶解和脱磷对乳化性的影响研究

卵黄高磷蛋白被发现比别的食品蛋白质的乳化性尤其乳液稳定性高。蛋白酶和磷酸酯酶可使乳化活性和乳液稳定性明显降低;卵黄高磷蛋白的蛋白酶水解导致大肽链(高磷酸化核心区50～210个肽)和小肽链裂解(N-端1～49个肽和C-端211～217个肽);不含小肽的肽不具备优秀的乳化特性,蛋白质中一部分小肽在乳化特性中扮演着重要角色;磷酸酯酶处理后,卵黄高磷蛋白中磷酸酯的静电排斥力对乳化性有显著影响;磷酸充分作用后的残基的这部分蛋白质对高乳化特性至关重要。