Impact of RN genotype and ageing time on colour characteristics of the pork muscles longissimus dorsi and semimembranosus

The effect of RN genotype on pH decline, ultimate pH, pigment content, blooming and colour stability during 6 days of display at 5 °C was studied in two pig muscles, M. longissimus dorsi (LD) and M. semimembranosus (SM), and furthermore the effect of anaerobic storage time (2 days vs. 9 days of ageing) on the same parameters was examined. The postmortem pH decline was faster and the ultimate pH lower in LD and SM of the RN⁻ genotype compared with corresponding muscles from the rn⁺ genotype. Pork of the RN⁻ genotype was initially lighter and more red and yellow than pork of the rn⁺ genotype due to a higher degree of blooming, which might be explained by the faster pH decline and/or lower ultimate pH. The level of oxymyoglobin (MbO₂) was decisive for the redness of both muscles during display in air despite a higher presence of metmyoglobin (MetMb). Pork of the RN⁻ genotype was thus redder than that of the rn⁺ genotype throughout display in air despite higher oxidation to MetMb. Ageing for 9 days in chill improved the blooming potential in pork of both genotypes compared with 2 days of ageing, resulting in superior meat colour. However, only in pork from the RN⁻ genotype, the colour was not negatively affected by ageing time upon display in air.     

模糊数据中异常点的一种识别方法

针对输入为确定数、输出为LR型模糊数的模糊数据集,利用最小二乘法建立了该模糊数据集的模糊线性回归分析模型及参数估计,用数据删除的方法研究了数据删除模糊线性回归模型,构造了统计诊断量—模糊Cook距离来识别模糊数据集中的异常点,通过数值模拟和对实例的研究,识别出其异常点,证实了本文构造的统计诊断量的有效性.     

黑曲霉苹果酸酶基因的敲除及其功能研究

通过敲除黑曲霉(Aspergillus niger)菌株ATCC1015的苹果酸酶(Malic enzyme,ME)基因,研究了ME基因敲除对黑曲霉TCA循环相关代谢的影响。利用农杆菌(Agrobacterium tumefaciens)介导的转化方法转化黑曲霉,通过同源重组敲除黑曲霉ME基因,筛选ME基因敲除菌株,获得了遗传性能稳定的ME基因敲除菌株。通过发酵实验,对比了野生菌株和ME基因敲除菌株在代谢产物累积方面的差异,发现ME基因敲除菌株的TCA循环中各种有机酸的产量与野生菌株相比没有明显变化。表明,ME基因的敲除对TCA循环没有产生明显影响。     

一个群签名成员删除方案的分析和改进

在群签名系统中群成员随时都可能离开,所以如何有效删除成员是一个重要的研究课题．王尚平等提出的成员删除方案(王删除方案)虽然其计算复杂性与成员删除数量无关,但笔者证明其不能达到真正删除成员的目的．基于王删除方案选择参数时所依据的数学原理,把成员注册和删除时的特性密钥更新算子由公开转为保密,同时特性密钥的更新工作由成员执行交由群主管执行,从而达到真正删除成员的目的,而且改进方案的计算量和原方案一样．     

利用杀配子染色体2C诱导中国春-长穗偃麦草1E二体附加系染色体畸变的研究

偃麦草属具有许多优良的遗传性状,利用杀配子染色体诱导小麦-偃麦草的染色体易位,是创建小麦异源易位系、丰富小麦遗传资源的一个有效途径。杀配子染色体2C在单体附加时,可高效率地诱导染色体畸变,得到易位、缺失等畸变类型。本研究利用含有杀配子染色体的中国春-柱穗山羊草2C(Ae.Cylindrical2n=28CCDD)二体附加系与中国春-长穗偃麦草(E.elongate2n=14EE)1E二体附加系杂交。观察F1花粉母细胞减数分裂情况,发现存在到量的染色体异常行为。单价体数超过理论值,棒状二价体数明显增加,并出现一定频率的三价体和四价体,及大量的染色体断片、染色体桥和落后染色体、微核,并伴随发生多极分裂现象。经C-分带与荧光原位分子杂交鉴定83株杂交F2,共检测到5株易位、6株缺失。易位频率为6.02%,缺失率为7.22%,染色体畸变的总频率为13.24%。并对杀配子染色体的诱变机制及引起杂交后代结实率降低的原因进行了讨论。     

The Thousand Polish Genomes—A Database of Polish Variant Allele Frequencies

Although Slavic populations account for over 4.5% of world inhabitants, no centralised, open-source reference database of genetic variation of any Slavic population exists to date. Such data are crucial for clinical genetics, biomedical research, as well as archeological and historical studies. The Polish population, which is homogenous and sedentary in its nature but influenced by many migrations of the past, is unique and could serve as a genetic reference for the Slavic nations. In this study, we analysed whole genomes of 1222 Poles to identify and genotype a wide spectrum of genomic variation, such as small and structural variants, runs of homozygosity, mitochondrial haplogroups, and de novo variants. Common variant analyses showed that the Polish cohort is highly homogenous and shares ancestry with other European populations. In rare variant analyses, we identified 32 autosomal-recessive genes with significantly different frequencies of pathogenic alleles in the Polish population as compared to the non-Finish Europeans, including C2, TGM5, NUP93, C19orf12, and PROP1. The allele frequencies for small and structural variants, calculated for 1076 unrelated individuals, are released publicly as The Thousand Polish Genomes database, and will contribute to the worldwide genomic resources available to researchers and clinicians.     

群签名中成员删除问题的更新算子解决方案

提出了Camenisch-Stadler群数字签名方案中成员删除问题的一个新的解决方案.新方案使用了群组成员秘密特性钥更新算子方法.新方案中当一个成员加入或被群组删除后,群主管计算并公布群组新的特性公钥及群组成员秘密特性钥更新算子,群中的每个成员只需要利用公开的更新算子重新计算各自的秘密特性钥,系统不需要对每个成员更新颁发成员证书.因此,新方案对大的群组是一个可接受的方案.群组的公开钥、成员的秘密钥及签名的长度都是固定不变的.新方案比Bresson-Stern的群组成员删除方案要好,因为Bresson-Stern的群组成员删除方案中对信息的签名含有证据,这些证据的个数随着被删除对象的个数呈线性增长.更新算子的思想受到了Kim-Lim-Lee的启发,但是该签名算法更为简明.所提出的方案的安全性是基于RSA问题的困难性假设,新方案是抗伪造攻击的,伪造成功等同于求解RSA问题.     

Delaunay三角网表示和点删除方法

对于三角网的表示方法,提出了一种双循环链表结构,这种结构能够方便的表示三角网的边拓扑和面拓扑信息,以及多边形结构.基于这种结构,对三角网点删除算法进行了改进.以前的点删除算法是基于连续的凸耳删除,提出的方法是基于多边形边的构建方法,利用D-三角网的空外接圆属性.与其它方法相比,这种方法具有容易理解,效率高的优点.