酸土脂环酸芽孢杆菌(Alicyclobacillus acidoterrestris)是引起橙汁劣变的主要微生物,为研究酸土脂环酸芽孢杆菌在橙汁中的生长规律,利用近红外光谱获取橙汁中酸土脂环酸芽孢杆菌含量的信息,采用标准化(autoscale)、多元散射校正(multip...酸土脂环酸芽孢杆菌(Alicyclobacillus acidoterrestris)是引起橙汁劣变的主要微生物,为研究酸土脂环酸芽孢杆菌在橙汁中的生长规律,利用近红外光谱获取橙汁中酸土脂环酸芽孢杆菌含量的信息,采用标准化(autoscale)、多元散射校正(multiplicative scatter correction,MSC)、标准正态变换(standard normal variate,SNV)、去趋势化(detrend)对光谱进行预处理,结合化学计量学,构建近红外光谱与酸土脂环酸芽孢杆菌含量预测模型。在此基础上,将近红外光谱转换为酸土脂环酸芽孢杆菌预测菌落数据,并采用“一步法”直接基于预测菌落数构建橙汁中酸土脂环酸芽孢杆菌的生长模型。结果表明,利用标准化进行光谱预处理建立的偏最小二乘(partial least squares,PLS)模型对橙汁中酸土脂环酸芽孢杆菌含量的预测效果相对较好,其预测决定系数(prediction determination coefficient,Rp2)与预测均方根误差(root mean square error of prediction,RMSEP)分别为0.733和0.242 lg CFU/mL,相对分析误差(relative percent deviation,RPD)为1.919。4种预测模型的均方误差(mean square error,MSE)介于0.0046~0.0300 lg CFU/mL之间;均方根误差(root mean square error,RMSE)介于为0.068~0.173 lg CFU/mL之间;赤池信息准则(akaike information criterion,AIC值)介于-66.383~-53.944之间,且Huang-full模型的3种指标相较更小,较适合描述橙汁中酸土脂环酸芽孢杆菌的生长。将近红外光谱获得预测菌落数构建的4种生长模型与平板计数法构建的生长模型分别进行相关性分析,发现4种模型的相关系数(r)均大于0.900,且Huang-full模型的拟合效果最优。所构建的模型通过准确因子(accuracy factor,Af)和偏差因子(bias factor,Bf)进行验证,证实模型均具有良好的可靠性。因此,利用近红外光谱分析结合适当的化学计量学方法描述酸土脂环酸芽孢杆菌生长预测是可行的。展开更多
Quantitative real-time PCR(qRT-PCR)has been widely used for gene expression analysis,and selection of reference genes is a key point to obtain accurate results.To find out optimal reference genes for qRT-PCR in Manila...Quantitative real-time PCR(qRT-PCR)has been widely used for gene expression analysis,and selection of reference genes is a key point to obtain accurate results.To find out optimal reference genes for qRT-PCR in Manila clam Ruditapes philippinarum in response to hypoxia,different tissues were used and compared to evaluate the stability of candidate reference genes under low oxygen stress(DO 0.5mgL^(−1) and DO 2.0mgL^(−1))and normal condition(DO 7.5mgL^(−1)).Seven candidate reference genes were selected to evaluate the stability of their expression levels.The reference genes were evaluated by Delta Ct,BestKeeper,NormFinder and geNorm,and then screened by RefFinder calculation.Under hypoxic stress of 0.5mgL^(−1),the most suitable reference gene for gill and hepatopancreas was RPL31,and the optimal reference genes for axe foot and adductor muscle were TUB and HIS,respectively.For hypoxic stress of 2.0mgL^(−1),the most stable reference gene for gill and hepatopancreas was RPL31,and the optimal reference genes for axe foot and adductor muscle were RPS23 and EF1A,respectively.At the normal condition,HIS and EF1A were identified as the optimal internal reference genes in gill and hepatopancreas respectively,and GFRP2 was the best internal reference gene for axe foot and adductor muscle.The present findings will provide important basis for the selection of reference genes for qRT-PCR analysis of gene expression level in bivalves under hypoxic stress,which might be helpful for the analysis of other molluscs too.展开更多
文摘酸土脂环酸芽孢杆菌(Alicyclobacillus acidoterrestris)是引起橙汁劣变的主要微生物,为研究酸土脂环酸芽孢杆菌在橙汁中的生长规律,利用近红外光谱获取橙汁中酸土脂环酸芽孢杆菌含量的信息,采用标准化(autoscale)、多元散射校正(multiplicative scatter correction,MSC)、标准正态变换(standard normal variate,SNV)、去趋势化(detrend)对光谱进行预处理,结合化学计量学,构建近红外光谱与酸土脂环酸芽孢杆菌含量预测模型。在此基础上,将近红外光谱转换为酸土脂环酸芽孢杆菌预测菌落数据,并采用“一步法”直接基于预测菌落数构建橙汁中酸土脂环酸芽孢杆菌的生长模型。结果表明,利用标准化进行光谱预处理建立的偏最小二乘(partial least squares,PLS)模型对橙汁中酸土脂环酸芽孢杆菌含量的预测效果相对较好,其预测决定系数(prediction determination coefficient,Rp2)与预测均方根误差(root mean square error of prediction,RMSEP)分别为0.733和0.242 lg CFU/mL,相对分析误差(relative percent deviation,RPD)为1.919。4种预测模型的均方误差(mean square error,MSE)介于0.0046~0.0300 lg CFU/mL之间;均方根误差(root mean square error,RMSE)介于为0.068~0.173 lg CFU/mL之间;赤池信息准则(akaike information criterion,AIC值)介于-66.383~-53.944之间,且Huang-full模型的3种指标相较更小,较适合描述橙汁中酸土脂环酸芽孢杆菌的生长。将近红外光谱获得预测菌落数构建的4种生长模型与平板计数法构建的生长模型分别进行相关性分析,发现4种模型的相关系数(r)均大于0.900,且Huang-full模型的拟合效果最优。所构建的模型通过准确因子(accuracy factor,Af)和偏差因子(bias factor,Bf)进行验证,证实模型均具有良好的可靠性。因此,利用近红外光谱分析结合适当的化学计量学方法描述酸土脂环酸芽孢杆菌生长预测是可行的。
基金supported by research grants from the Science and Technology Innovation Program of the Laoshan Laboratory(No.LSKJ202203803)the National Natural Science Foundation of China(No.32273107)+2 种基金supported by the Central Public-Interest Scientific Institution Basal Research Fund,Yellow Sea Fisheries Research Institute,CAFS(No.20603022022001)the project of Putian Science and Technology Department(No.2021NJJ002)the Shinan District Science and Technology Plan Project(No.2022-2-026-ZH).
文摘Quantitative real-time PCR(qRT-PCR)has been widely used for gene expression analysis,and selection of reference genes is a key point to obtain accurate results.To find out optimal reference genes for qRT-PCR in Manila clam Ruditapes philippinarum in response to hypoxia,different tissues were used and compared to evaluate the stability of candidate reference genes under low oxygen stress(DO 0.5mgL^(−1) and DO 2.0mgL^(−1))and normal condition(DO 7.5mgL^(−1)).Seven candidate reference genes were selected to evaluate the stability of their expression levels.The reference genes were evaluated by Delta Ct,BestKeeper,NormFinder and geNorm,and then screened by RefFinder calculation.Under hypoxic stress of 0.5mgL^(−1),the most suitable reference gene for gill and hepatopancreas was RPL31,and the optimal reference genes for axe foot and adductor muscle were TUB and HIS,respectively.For hypoxic stress of 2.0mgL^(−1),the most stable reference gene for gill and hepatopancreas was RPL31,and the optimal reference genes for axe foot and adductor muscle were RPS23 and EF1A,respectively.At the normal condition,HIS and EF1A were identified as the optimal internal reference genes in gill and hepatopancreas respectively,and GFRP2 was the best internal reference gene for axe foot and adductor muscle.The present findings will provide important basis for the selection of reference genes for qRT-PCR analysis of gene expression level in bivalves under hypoxic stress,which might be helpful for the analysis of other molluscs too.
文摘针对鸡蛋液中菌落总数分析方法操作繁琐、时效性低等问题,采用高光谱成像技术(400~1 000 nm)建立鸡蛋液中菌落总数的快速预测方法。于蛋清中接种铜绿假单胞菌后采集不同污染程度蛋液样本的原始高光谱信息,结合连续投影算法进行特征波段的提取,分别建立基于特征波段和全波段光谱信息下的偏最小二乘和支持向量机(support vector machine,SVM)预测回归模型。结果表明:标准化预处理效果相对最佳,蛋清、蛋黄以及全蛋液样本对应的相对最佳定量分析模型为基于特征波段下的SVM模型。其中蛋清预测集相关系数RP为0.81,预测集均方根误差(root mean square error of prediction,RMSEP)为0.63(lg(CFU/g));蛋黄预测集的R_P为0.82,RMSEP为0.47(lg(CFU/g));全蛋液样本中RP为0.75,RMSEP为0.75(lg(CFU/g))。结果表明,高光谱成像技术结合化学计量学方法,可以实现对鸡蛋内部微生物污染程度的定量预测。