Protein evolution: causes of trends in amino-acid gain and loss

Understanding how proteins evolve is important for determining the molecular basis of adaptation, for inferring phylogenies and for engineering novel proteins. It has been suggested that some amino acids were incorporated into the genetic code more recently than others and, after comparing pairs of closely related genomes, Jordan et al. report that 'recent' amino acids are becoming more common. They argue that this process has been going on since the genetic code first evolved to encompass all 20 amino acids. Here we provide evidence that the patterns observed conform with standard, nearly neutral theoretical expectations and require no new explanation. This reinforces the need for caution in the interpretation of results derived from closely related taxa.     

Multiple intron gain and loss events occurred during the evolution of Cenp-A gene

Centromere protein A(CENP-A) is a histone H3 like protein,and it plays a very important role in chromosomal segregation during mitosis and meiosis.The analyses on the exon-intron organization of the Cenp-A gene in representative genomes revealed that multiple intron gain and loss events have occurred during the evolution of Cenp-A gene in opisthokonta(common ancestor of fungi and animals).Moreover,our results revealed that at least two positions were conserved in the intron gain and loss events during the evolution of the Cenp-A gene.     

小麦麸皮蛋白质的提取及其氨基酸组分分析

小麦麸皮主要含有纤维、蛋白质和淀粉,为实现其分层利用,提高其附加值,对小麦麸皮中的蛋白质分离工艺进行研究,并对其氨基酸组成进行分析。文章采用碱提酸沉方法提取小麦麸皮中的蛋白质,以小麦麸皮中蛋白质残留率为指标优化其提取效果。结果表明:在pH值为12左右、料液比为1∶15、温度为50℃、时间为3h时,小麦麸皮中蛋白质提取效果最佳,可达到小麦麸皮质量的15.85%,pH=3.8为最佳沉淀点;氨基酸组成分析表明小麦麸皮中含有13种氨基酸,其中8种必需氨基酸占提取蛋白质质量的20.4%,是一种良好的食用植物蛋白质资源。     

Prediction of protein structure from amino acid sequence.

In principle, it is possible to predict theoretically the three-dimensional structure of a protein from its amino acid sequence. Recently substantial progress towards this goal has been made by the use of simple models to represent protein conformation and interatomic interactions, together with the knowledge gained form analyses of know protein structures.     

中国林蛙不同部位蛋白质和氨基酸的分布

对１－３龄中国林蛙的输卵管、卵和去内脏躯体中蛋白持和氨基酸含量进行了测定比较，结果表明，各龄中国林蛙各部位都富含蛋白质和氨基酸，但不同部位的含量不同，输卵管中蛋白质和氨基酸含量相对较低，而其必需氨基酸配比明显最高，卵和去内脏躯体在氨基酸组成上有一定的相似性，不同部位的蛋白质和氨基酸含量随蛙龄变化的趋势不一样，３龄蛙越冬前后各部位蛋白质及氨基酸含量差异不显著，雌雄去内脏躯体对比也无明显差异。     

蛋白质结构中氨基酸残基聚集体的识别与分析

在蛋白质结构中，氨基酸残基并不是单独行使其功能．几个残基通常聚集在一起，共同承担生物学角色．本文通过对蛋白质结构内残基的空间分布进行分析，提取出从两个残基到五个残基的组合，并统计出它们出现的频率和频率分布．二元组在维系蛋白质三级结构中起重要作用，而三元组、四元组和五元组与蛋白质的功能有着密切的关系．这些多元组可为蛋白质结构及功能的研究提供必要的信息．     

子代发育管控(ODC):生物有性生殖进化的一个普遍趋势

达尔文认为,所有的生物都在进化.问题是如何进化?生物进化是否有一个普遍的模式或趋势?这些问题很少有人问到,也几乎没有人能够回答.在这种情况下,对许多人来说,进化是使人沮丧而又充满神秘的议题.在调查了大多数动植物的繁殖模式后,我们认为,所有(至少是大多数)生物的生殖进化都显示了类似的趋势,即子代发育管控(ODC).子代发...     

Structure and mobility of electron gain and loss centres in proteins

Radiation damage to proteins is a topic of intense interest to those involved in radiation effects in biology, and also to those involved in radiotherapy. Although it has been widely studied, fundamental processes in protein damage are very hard to specify because of the complexity of the final damage products. But the non-invasive technique of electron-spin resonance is ideally suited to the task of detecting and identifying the primary and secondary products as these are expected to contains unpaired electrons (that is, free-radicals) and such species are uniquely detected by this sensitive form of spectroscopy. Our present study shows that a major radical species formed by electron loss in a range of proteins is the backbone amido radical, -N.(CO)-, characterized by hyperfine coupling to one 14N nucleus. These centres are efficiently trapped in proteins at low temperatures. In contrast, the expected backbone electron-capture centres, -NH(CO.-)-, are not readily trapped and electron transfer occurs until the ejected electron is trapped by some electrophilic centre. Such electron mobility was in fact established in our previous work on oxyhaemoglobin (FeO2----FeO2-), superoxide dismutase (Cu(II)----Cu(I] haemocyanin (Cu(II)O2Cu(I)----Cu(I)O2Cu(II] and various proteins containing S-S bonds (-S-S-)----(-S.-S-) (refs 1-4 respectively). This is strongly supported by our observation that such electrons are captured by DNA molecules, giving T.- centres, when nucleohistones are irradiated, and that Fe(CN)3-(6) ions readily scavenge such electrons from proteins which are devoid of highly electrophilic centres.     

宇宙大爆炸及宇宙演化

给出了宇观天体和微观粒子质量、半径的统一计算式,计算结果与实验基本相符.认为宇宙大爆炸是"超微黑洞"(即前宇宙)的大爆炸,否定了点大爆炸的传统观点.爆炸后的宇宙背景是光子热平衡态和引力束缚态共存的系统,平衡态占优势则宇宙必然膨胀.暗物质、暗能量的本质是什么?它们会怎样左右宇宙的命运?最后也阐明所谓的"大沙漠"区并非一无所有,它分布着三代费米子的超对称伴子--三代玻色型粒子成员.     

俄语称谓的特点及其演变趋势

自苏联解体以来，俄罗斯社会在政治改革、经济建设、意识形态及文化生活等各个领域发生了巨大的变化，这些剧变对本国语言产生了很大的影响。俄罗斯人在日常生活和社会工作的各个场合以及在报刊等新闻媒体上出现的称呼用语发生了变化，并逐渐呈现新的发展趋势。     

元宝枫及同属植物种子总蛋白质含量和氨基酸的测定

对元宝枫及同属植物种子总蛋白质含量和氨基酸的组成进行了分析测定，结果表明元宝枫及同属植物种子含有较高的蛋白质，且其氨基酸的组成以谷氨酸、精氨酸含量较高为特点．     

高效液相色谱测量啤酒中氨基酸

本文建立了测量啤酒氨基酸的有效方法,该方法使用高效液相色谱采用梯度洗脱测定啤酒中的氨基酸,结果回收率为99.2%,RSD为2.01%,表明本方法精密度高,稳定性好,可作为检测啤酒氨基酸有效方法。     

大鼠中性氨基酸转运蛋白SNAT1-HA融合蛋白的构建和表达(英文)

Na+偶联的中性氨基酸转运蛋白SNAT1是一种膜蛋白,属于转运蛋白第38家族(SLC38),在中枢神经系统(CNS)中起到重要的生理学作用.为了更容易地检测SNAT1在细胞膜上的表达,以pBK-CMVΔ-SNAT1为模板,用PCR,双酶切和T4连接酶连接的方法在SNAT1的C端加上了一个HA标签蛋白,构建了一个新质粒pBK-CMVΔ-SNAT1-HA.用该质粒瞬时转染人胚胎肾细胞(HEK293T),转染36 h以后,融合蛋白SNAT1-HA可以用HA抗体检测.Western blot结果显示在约54 kDa处有一条特异性条带,与预期分子量大小一致.利用重组质粒pBK-CMVΔ-SNAT1-HA可以更方便地检测到SNAT1在细胞膜上的表达与定位,为进一步研究SNAT1结构与功能奠定了基础.     

PITC derivatives in amino acid analysis

Refined methods for separating PTC-amino acids on reverse phase columns may pose a challenge to traditional ion exchange techniques.     

金属离子与氨基苯甲酸及吡啶单羧酸配合物的研究

合成了２１种金属离子Ｌａ（Ⅲ）Ｃｕ（Ⅱ）Ｎｉ（Ⅱ）和Ｃｏ（Ⅱ）与氨基苯甲酸及吡啶意境羧酸的化合物，其中１４种是尚未报道过的新化合物，通过元素分析，红外光谱、Ｘ－射线粉末衍射，ＴＧ－ＤＴＧ等表征了产物的结构特征和热分解过程，表明，配体酸中氨基和羧基的相对位置影响着配体酸与金属离子的反应能力和反应产物的稳定性。     

斯里兰卡极端降水时空演变特征及趋势预测

斯里兰卡是我国“一带一路”战略的重要节点国家,极端降水对当地社会经济威胁较大,极易引发灾害。本文选取当地10个气象站2008~2020年的逐日降水资料,基于RClimDex模型计算斯里兰卡6个极端降雨指标,利用经验正交函数分析、Morlet小波分析和R/S分析等方法,分析极端降水事件的时空演变特征。结果表明：极端降水指数在时间分布上,除持续干旱指数（CDD）呈减少趋势外,其他各指数均为上升趋势;极端降水指数空间差异表现为北部沿海平原地带的极端降水强度高于南部沿海平原,拉特纳普勒市以西地区为斯里兰卡降雨事件的多发区;极端降水指数周期性明显,绝大多数极端降水指数以6~7年为第一主周期。R/S分析表明当地极端降水事件未来持续可能性较大。研究结果可为斯里兰卡极端气候预测、生态环境保护、防灾减灾工作等提供决策支持。     

Adaptive protein evolution in Drosophila

For over 30 years a central question in molecular evolution has been whether natural selection plays a substantial role in evolution at the DNA sequence level. Evidence has accumulated over the last decade that adaptive evolution does occur at the protein level, but it has remained unclear how prevalent adaptive evolution is. Here we present a simple method by which the number of adaptive substitutions can be estimated and apply it to data from Drosophila simulans and D. yakuba. We estimate that 45% of all amino-acid substitutions have been fixed by natural selection, and that on average one adaptive substitution occurs every 45 years in these species.     

东北地区经济增长的时空差异和演化趋势

以东北地区36个地级市为研究对象,从时间、空间两个维度对其经济增长的差异性及其演化趋势进行测算与分析.通过标准差、变异系数对1998—2012年东北地区经济增长的差异程度测算结果表明:15年间东北地区经济总量增长较快,36个地级城市之间经济增长的绝对差异逐年加大,相对差异在波动中不断减小;相对发展率的东北地区区域经济增长空间特征分析显示:相对发展率高的城市主要位于辽宁、吉林两省;运用Theil指数对经济增长差异驱动力分析表明:区内差异的贡献率在地区总差异、区域间差异、区域内差异等三要素中最大;采用R/S分析法对未来15年地区经济增长的差异性演化预测显示:东北地区经济增长的差异性在2013—2027年间仍将呈波动递减趋势,但后期递减的趋势会由较弱趋向平稳.