Detection and genetic diversity of porcine rotavirus A,B and C in eastern Australian piggeries

Rotaviruses (RV) have a high prevalence in piggeries worldwide and are one of the major pathogens causing severe diarrhoea in young pigs. RV species A, B, and C have been linked to piglet diarrhoea in Australian pig herds, but their genetic diversity has not been studied in detail. Based on sequencing of the structural viral protein 7 (VP7) RVA G genotypes G3, G4 and G5, and RVC types G1, G3, G5, and G6 have been identified in Australian piggeries in previous studies. Although occurrence of RVB was reported in Australia in 1988, no further genetic analysis has been conducted. To improve health management decisions in Australian pig herds, more information on RV prevalence and genetic diversity is needed. Here, 243 enteric samples collected from 20 pig farms within Eastern Australia were analysed for the presence of RV in different age groups using a novel PCR-based multiplex assay (Pork MultiPath™ enteric panel). RVA, RVB, and RVC were detected in 10, 14, and 14 farms, respectively. Further sequencing of VP7 in selected RV-positive samples revealed G genotypes G2, G5, G9 (RVA), G6, G8, G14, G16, G20 (RVB), and G1, G3, G5, G6 (RVC) present. RVA was only detected in young (<10 weeks old) pigs whereas RVB and RVC were also detected in older animals (>11 weeks old). Interestingly, RVB and RVC G-type occurrence differed between age groups. In conclusion, this study provides new insights on the prevalence and diversity of different RV species in pig herds of Eastern Australia whilst demonstrating the ability of the Pork MultiPath™ technology to accurately differentiate between these RV species.     

莲藕淀粉RVA谱特征和淀粉粒形态的研究

 对莲藕根状茎成熟期淀粉特性的研究结果表明: 4个品种表观直链淀粉含量(AAC) 从高到低依次为‘美人红’、‘鄂莲1号’、‘鄂莲4号’和‘武植2号’。根状茎中淀粉粒形态主要有近圆球形和长椭球形两种, 武植2号和鄂莲4号近圆球形淀粉粒明显多于鄂莲1号、美人红。武植2号和鄂莲4号的淀粉糊化特性相似, 其峰值粘度均较高, 冷胶粘度显著低于峰值粘度, 且回复值较小, 消减值为负值; 鄂莲1号和美人红的峰值粘度均较小, 冷胶粘度接近甚至大于峰值粘度, 回复值、消减值均显著大于武植2号和鄂莲4号。AAC与峰值粘度和崩解值呈极显著负相关, r分别为- 0.9748^**和- 0.9793^**, 与回复值、消减值呈极显著正相关, r分别为0.9860^**和0.9804^**, 与冷胶粘度、峰值时间、糊化温度呈显著正相关, r分别为0.9339^*、0.9392^*、0.9130^*。淀粉粒形态结构上的差异可能造成了淀粉糊化特性的差异。     

Enzymatic extraction of beta-glucan from oat bran cereals and oat crackers and optimization of viscosity measurement

The viscosity of the soluble fibre, β-glucan, has been shown to influence its ability to lower serum cholesterol and postprandial blood glucose levels. The impact of various amylases, proteases and lipase on the solubility and resulting viscosity of β-glucan extracted from oat bran cereals with a range of β-glucan concentrations and molecular weights was investigated. Addition of enzymes increased the final viscosity of high molecular weight β-glucan in cereals by facilitating the release of β-glucan from the food matrix. For cereals with partially depolymerized β-glucan, the addition of digestive enzymes decreased the final viscosity by eliminating the contribution of starch and protein to viscosity. Final viscosity varied depending on enzyme combinations including pancreatin, salivary and microbial α-amylases, microbial protease, porcine protease, trypsin and α-chymotrypsin. Addition of lipase did not significantly affect viscosity or solubility of β-glucan extracted from oat crackers. Addition of lichenase showed that β-glucan was the major contributor of viscosity to the system, with negligible interference from other components. The viscosity of the optimized protocol was compared to physiological results previously obtained. The viscosity of β-glucan extracted with pancreatin plus microbial α-amylase (pH 6.9) was predictive of LDL-cholesterol reduction (R² = 0.847) and glycemic response (R² = 0.883).     

施氮量对水稻主要米质性状及RVA谱特征参数的影响

在盆栽试验条件下，以汕优63、武育粳3号为试验材料，研究水稻移栽后的施氮量对主要米质性状和RVA谱特征参数的影响。结果表明：整精米率、粗蛋白含量均随施氮量的增加而提高；垩白粒率、垩白度对供氮水平的反应因品种而异；胶稠度随施氮量的提高两者都变软；直链淀粉含量、糊化温度对氮素反应不敏感，处理间无显著差异。稻米     

稻米淀粉RVA谱特征与品质性状相关性研究

 通过2年分别对114个和101个水稻品种（系）的各项品质指标及RVA谱的测定，研究了RVA谱特征值与外观品质、蒸煮理化指标、食味品质的相关关系。结果表明：（1）RVA谱特征值与外观品质中的透明度、垩白率关系较密切。同一品种的稻米，有垩白比无垩白米的表观直链淀粉含量（AAC）要高，热浆粘度、冷胶粘度、消减值、回复值大。（2）RVA谱特征值与蒸煮理化指标中的AAC、胶稠度（GC）相关极为显著，与糊化温度(GT)相关性不显著;（3）除最高粘度外，RVA谱的其余特征值与食味品质的主要指标呈极显著相关。以上结果表明，RVA谱特征值可以作为优质稻米的辅助选择指标。     

不同生育期甘薯块根淀粉糊化特性的差异

 采用差示扫描量热分析仪（DSC）和淀粉粘度速测仪（RVA）分析了3个甘薯品种（系）在块根发育过程中淀粉糊化特性的变化。结果表明，随甘薯生育期的延长，3个品种的淀粉率都呈下降趋势，但直链淀粉率的变化则因品种而异。早期收获，徐薯18和浙大9201的直链淀粉率表现较高，而浙3449则较低。随生育期延长，DSC糊化峰向低温方向移动，且峰宽增大、峰逐渐消失，其糊化温度和热焓变化也随之递减，而RVA的最高粘度则呈现递增趋势。相关分析发现，甘薯直链淀粉含量与各糊化特性参数间存在一定相关性，但这种相关性的大小又受到品种制约。     

灌浆成熟期光照强度对早籼稻直链淀粉含量及淀粉RVA谱特性的影响

选择浙江省推广种植的直链淀粉含量差异较大的3个早籼稻品种，通过5个不同的遮光处理，研究了灌浆成熟期光照强度对早籼稻米直链淀粉及其淀粉RVA谱的影响。结果表明，除品种与光强互作对消减值的效应未达显著水平外，品种、光强及其互作效应对直链淀粉含量及淀粉最高黏度、热浆黏度、崩解值、冷胶黏度和消减值的效应均达显著或极显著水平。灌浆成熟期光照强度对淀粉最高黏度和冷胶黏度的影响最大，对热胶黏度、崩解值和直链淀粉含量的影响也较大，而对直链淀粉含量和消减值的影响则相对较小。最高黏度和崩解值均随着光照强度的下降而明显下降，稻米蒸煮食味品质显著降低。     

不同氮肥水平对稻米品质和淀粉RVA谱特征的影响

以优质迟熟中梗稻“通育粳1号”为材料,研究了不同氮肥水平对水稻产量、稻米品质和RVA谱特征的影响。结果表明,大田施N量在0～450kg/hm^2范围内,产量随施N量的增加而增加,但增幅递减;高施氮量的加工品质优于不施肥或低施氮量的处理;随着施氮量增加,稻米垩白率减少、垩白度下降,外观品质而明显改善;胶稠度随施氮量的增加而下降,直链淀粉含量总体上趋于减少,而蛋白质含量则增加;不同氮素水平稻米淀粉RVA谱的变化显示,随施氮量增加,最高粘度降低,崩解值下降,消碱值增加,糊化温度升高。控施氮肥有利于提高稻米的食味品质。综合产量和品质性状,以施氮量225．0kg／hm^2的处理为最佳。     

国标优质籼稻的稻米品质与淀粉RVA谱特征研究

【目的】了解国标优质籼稻的米质特点.【方法】以广东省最近育成的水稻品种粤晶丝苗2号等为研究材料,对稻米碾磨品质、外观品质、蒸煮食味品质、营养品质和淀粉RVA谱进行了测定和相关分析.【结果和结论】国标优质籼稻具有整精米率较高、粒型窄长、腹心白少、透明度好、直链淀粉含量适中和长胶稠度等优点;蛋白质含量品种间差异不大,脂肪酸含量品种间的差异较大,粤秀占、巴太香1号、粤晶丝苗2号的脂肪酸含量较高;国标优质籼稻的RVA谱具有高崩解值、低消减值的特点,食味品质优于非国标优质籼稻,其中粤晶丝苗2号的崩解值和消减值符合公认的优质食味指标值,是一个食味品质优良的籼稻品种.直链淀粉、胶稠度与RVA谱的冷胶黏度、崩解值和消减值密切相关,在水稻品质育种中增加RVA谱测定,尤其是将直链淀粉、胶稠度的选择与崩解值、碱消值分析相结合,可有效地提高水稻食味品质选择的准确性.     

蛋白质影响水稻米饭食味品质的机理

 以杂交中籼丰两优1号组合为材料,设置不同的播期和收获期,分析稻米主要品质指标(直链淀粉、总蛋白含量、RVA特征值等)和米饭食味品质,并用二硫苏糖醇 (DTT)或蛋白酶(Trypsin)分别打破样品蛋白质二硫键或酶解蛋白质后,观察RVA特征谱和膨胀势的变化,旨在明确蛋白质对不同食味品质样品RVA的影响,进而探索蛋白质影响米饭食味品质的机理。结果表明,第3播期(6月13日)稻米品质主要指标（直链淀粉、总蛋白、膨胀势、RVA特征值）与第4播期（6月23日）样品差异不显著,但食味品质明显好于后者;分别经蛋白酶处理后,第3和第4播期样品RVA上升段斜率差异不显著,但前者后段冷却后回升斜率明显小于第4播期。由于影响RVA特征谱后段凝胶刚性的主要因素是淀粉与水之比,刚性随淀粉凝胶中含水量减少而提高,食味品质较好的第3播期米粉经蛋白酶处理后,凝胶刚性小且减弱程度大,这可能是蛋白质酶解后形成蛋白质碎片的持水能力弱,即淀粉与水之比低,由此推测蛋白质影响米饭食味品质可能在米饭蒸煮后阶段,即可能与蛋白质水合后持水能力差异有关。