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1.
安徽百合属细胞学研究   总被引:5,自引:0,他引:5  
本文研究了安徽产百合属(LiliumL.)2种和2变种的染色体数目和核型,结果如下:野百合(L.browniiF.E.Brown)观察了2个居群。歙县居群观察到两种细胞型,细胞型Ⅰ:2n=26=1m+2Sm+10St+10t+3T;细胞型Ⅱ:2n=24+2Bs=2m+2Sm+8St(2sc)+12t+2Bs;石台居群核型公式为2n=24+1Bs=3m+1Bm+6St+12t+2T+1Bs。百合(L.browniiF.E.Brownvar.viridu-lumBaker)核型公式为2n=24+1Bs=4m(2sc)+14St(2sc)+6t+1Bs;药百合(L.speciosunThunb.var,gloriosoidesBaker)核型公式为2n=24=4m+9St(2sc)+10t+1T;条叶百合(L.callosumSieb.etZuce.)核型公式为2n=24=2m+2Sm+4St(2sc)+16t。以上的核型类别全部属于“3B”型,其中野百合2n=26的染色体数目和核型为首次记录。  相似文献   

2.
根据价键理论、杂化轨道理论和离域π键概念,提出共价ABqn型粒子中离域π键的判断公式πm=m1+nm2+q-2(Q+nQ-n)n+1,并以实例验证了公式的可靠性.  相似文献   

3.
根据价键理论,杂化轨道理论和离域π键概念,提出共价AB^qn型粒子中离域π键的判断公式,π^m=m+nm2+q-2(Q+nQ-n),n+1并以实验验证了公式的可靠性。  相似文献   

4.
张莹  黄仿  刘明登  彭秀  张健 《广西科学》2000,7(1):57-58
为了探讨珊瑚中的钙在生物体内的吸收利用情况,将30只小白鼠随机分为3组,雌雄各半,分别喂食大鸭料+CaO+乳酸(A组),大鸭料+CaO+乳酸+混合氨基酸(B组),大鸭料(C组)。结果:3组小鼠的体重没有显著差异;B组小鼠股骨重量和长度与A组,C组有显著差异。A组与C组没有显著差异;结果表明混合氨基酸能促进珊瑚中的钙在动物体内的吸收利用,使动物骨骼增重、增长。  相似文献   

5.
安徽黄精和琅琊黄精核型初步研究   总被引:2,自引:0,他引:2  
本文对黄精属(Polygonatum Mill.)中安徽特有2种植物的核型进行了初步研究,并分别人近缘种的核型进行了比较。结果表明:安徽黄精(P.anhuiense)核型公式为2n=24=4m+6sm+12st=2T,属3B核型,染色体相对长度组成为2n=24=6L+6M2+6M1+6S.琅琊黄精(P.langyaense)核型公式为2n=18=10m+2sm+6st,属2B核型;染色体相对长度组  相似文献   

6.
本文提出了计算MnBm型弱碱弱酸盐溶液精确[H^+]的普适公式,一般迭代1 ̄2次便可求出[H^+]的精确解。  相似文献   

7.
本文提出了计算酸式盐和MB型弱碱弱酸盐溶液[H+]精确解的新公式和迭代判据,一般迭代1~2次便可求出[H+]的精确解  相似文献   

8.
本文提出了计算MnBm型弱碱弱酸盐溶液精确[H+]的普适公式,一般选代1~2次便可求出的[H+]的精确解  相似文献   

9.
参照人的BDNF基因序列设计了一对引物,利用聚合酶链式反应(PCR),从小熊猫基因组DNA中扩增和克隆到BDNF基因。序列分析表明,小熊猫和人的BDNF基因核苷酸序列同源性为93%,而与大熊猫BDNF基因的核苷酸序列同源性高达98%。在推导的多肽序列中,除在前导肽区有两个氨基酸的差异外,小熊猫BDNF的成熟区与人和其他报道的哺乳动物BDNF成熟区的氨基酸序列完全一致,显示了极高的保守性。  相似文献   

10.
本文提出了计算酸式盐和MB型弱碱弱酸盐溶解[H^+]精确解的新公式和迭代判据,一般迭代1 ̄2次便可求出[H^+]的精确解。  相似文献   

11.
富硒大豆蛋白经过酶解、超滤、调配、杀菌等工艺,制备成富硒大豆低聚肽口服液,分析了产品中的硒含量、大豆低聚肽含量及氨基酸组成,其中硒含量2.45 mg/100 ml,大豆低聚肽含量(分子量1000 D以下)达到638.25 mg/100 ml,含有Se-Cys在内的19种氨基酸,研究结果为富硒大豆低聚肽产品的质量标准制定提供了一定的理论依据.  相似文献   

12.
D S Kemp  J G Boyd  C C Muendel 《Nature》1991,352(6334):451-454
Formation of alpha helices from disordered polypeptides depends on the degree to which amino acids favour the helical state. The folding of helical oligopeptides can be modelled by two parameters: sigma which reflects helix initiation and s which reflects propagation of a pre-existing helix and measures helical bias. Scheraga has reported s values for oligopeptides of about 1.1, implying a weak helical bias for amino-acid residues. By contrast, certain helical peptides studied by Baldwin seem to require much larger s values for alanine. Resolution of this inconsistency requires experiments that disentangle the ease of propagation from that of initiation. In this study varying lengths of polyalanine are linked to a 'template' that initiates helical structure and permits study solely of propagation. We report here that the s value for alanine in water is close to 1, supporting the earlier results of Scheraga but not the more recent results of Baldwin.  相似文献   

13.
复合酶降解羽毛粉的效果研究   总被引:1,自引:0,他引:1       下载免费PDF全文
运用物理法与酶解法相结合的方法,对一种复合酶的酶解效率进行了研究.羽毛粉经高温高压处理后,采用不同复合酶浓度和不同酶解时间对羽毛粉样品进行酶解,通过测定其中的可溶性蛋白质含量、胃蛋白酶消化率来考察其酶解效率,并且对酶解上清液中多肽和氨基酸进行初步的分析.研究结果表明,该复合酶在一定的条件下可有效降解羽毛产生的多肽、寡肽和游离氨基酸,并且酶解上清液中多肽和氨基酸的分子量均在6 kDa以下.  相似文献   

14.
目的研究兰州鲇(Silurus lanzhouensis)肌肉中常规营养成分和不同季节中肌肉水解氨基酸的组成和含量。方法采用氨基酸自动分析仪测定肌肉中水解氨基酸。结果兰州鲇肌肉中含有18种氨基酸,组成和含量顺序未呈现出季节性变化特点;蛋氨酸、异亮氨酸、亮氨酸、天冬氨酸、丙氨酸这5种氨基酸的含量及氨基酸总量,均随季节的推移呈上升趋势,但在3个季节中仅有秋季显著高于春季(P<0.05);苏氨酸、丝氨酸和谷氨酸等9种氨基酸的含量和必需氨基酸总量等虽有季节性上升趋势,但在3个季节间均无显著差异(P>0.05);胱氨酸、组氨酸和精氨酸等4种氨基酸含量未呈现出季节性变化。结论兰州鲇是一种蛋白质含量较高的经济鱼类,肌肉中水解氨基酸的种类、含量顺序及多数氨基酸的含量在季节变化中有较大的保守性。  相似文献   

15.
Molecular cloning of cDNA for murine interleukin-3   总被引:51,自引:0,他引:51  
The cDNA sequence for murine interleukin-3, one of the colony stimulating factors that regulate haematopoiesis, codes for a polypeptide of 166 amino acids including a putative signal peptide. The predicted amino acid sequence indicates that formation of mature interleukin-3 involves proteolytic removal of not only the signal peptide but additional amino-terminal amino acids.  相似文献   

16.
ECBP21 is an extracellular calmodulin-binding protein which was first detected and purified from extracellular extracts of suspension-cultured cells of Angelica dahurica. The purified protein was electroblotted onto PVDF membrane and the amino acid sequences from 1 to 20 were determined. Using degenerate oligonucleotides of the sequence, a full-length cDNA coding for ECBP21 was isolated by a combination of RT-PCR and 5′-RACE cloning. The cDNA contains 947 nucleotides and codes for a precursor protein of 216 amino acids. The N-terminal 1-25 amino acid sequence is a predicted signal peptide and the other 26-216 amino acid sequence is a mature peptide. The 26-45 amino acid sequence shows identity with the N-terminal amino acid sequence of purified ECBP21 from Angelica dahurica. The fragment of encoding the mature protein was cloned into pET-28b(+) and transformed into E. coli BL21(DE3). A protein with relative molecular mass 21 ku was expressed in E. coli. Using a biotinylated-CaM gel overlay technique, the expression protein was tested for its ability to bind CaM. The results indicated that the expression protein is a Ca2+- dependent CaM-binding protein. Thus, these results further defined the cDNA clone for ECBP21. This work laid a foundation for elucidating biological functions of ECBP21 by using molecular biological means.  相似文献   

17.
利用RACE(rapid amplification of cDNA end)方法, 以大豆叶片提取总的RNA为模板克隆了大豆Na+/H+逆向转运蛋白(Glycine max Na+/H+ antiporter, GmNHX)基因, 并将其连接到表达载体PBI121中, 构建重组表达载体PBI121 NHX3. 分析结果表明: 该基因的ORF为1 503 bp, 推测编码501个氨基酸. 与所选取的10种植物同类蛋白氨基酸序列进行对比, 一致性为72%~94%, 并具有真核生物单价阳离子(氢离子)反向转运蛋白典型的结构域, 将该基因命名为GmNHX3, GenBank接收号为JN872904. 通过PCR和酶切鉴定, PBI121 NHX3构建成功.  相似文献   

18.
大熊猫IL-2基因的克隆与序列分析   总被引:1,自引:0,他引:1  
本实验应用反转录-聚合酶链反应(RT-PCR)技术,从ConA诱导培养的大熊猫外周血淋巴细胞总RNA中扩增得到大熊猫IL-2基因,并将其克隆到PGEM-T载体中.经菌落PER鉴定、序列测定及序列分析,结果表明,经克隆得到的IL-2基因开放阅读框由465个核苷酸组成,编码一个由155个氮基酸组成的多肽,包括编码20个氨基酸的信号肽和135个氨基酸的成熟肽,该基因(已在Genbank中登录,序列号为:DQ852339)与已知的其他哺乳动物如犬、猫、人、猪、牛、羊、马、兔、鼠等的IL-2核苷酸同源性在66.5%(鼠)~91.5%(犬)之间;IL-2编码氨基酸同源性在54.8%(鼠)-85.2%(犬)之间;进化树构建结果表明大熊猫与犬亲缘关系最近.  相似文献   

19.
Amino acid composition of proteins varies substantially between taxa and, thus, can evolve. For example, proteins from organisms with (G + C)-rich (or (A + T)-rich) genomes contain more (or fewer) amino acids encoded by (G + C)-rich codons. However, no universal trends in ongoing changes of amino acid frequencies have been reported. We compared sets of orthologous proteins encoded by triplets of closely related genomes from 15 taxa representing all three domains of life (Bacteria, Archaea and Eukaryota), and used phylogenies to polarize amino acid substitutions. Cys, Met, His, Ser and Phe accrue in at least 14 taxa, whereas Pro, Ala, Glu and Gly are consistently lost. The same nine amino acids are currently accrued or lost in human proteins, as shown by analysis of non-synonymous single-nucleotide polymorphisms. All amino acids with declining frequencies are thought to be among the first incorporated into the genetic code; conversely, all amino acids with increasing frequencies, except Ser, were probably recruited late. Thus, expansion of initially under-represented amino acids, which began over 3,400 million years ago, apparently continues to this day.  相似文献   

20.
基于FAO/WHO氨基酸评分模式,运用氨基酸比值系数法,对顶坛花椒幼嫩茎叶必需氨基酸进行分析评价,结果表明:顶坛花椒幼嫩茎叶氨基酸比值系数分为71.96,必需氨基酸组成合理,营养价值高,第一限制氨基酸为蛋氨酸(含胱氨酸)。  相似文献   

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