乙肝病毒突变核心蛋白基因的克隆及序列分析

目的克隆发生长片段缺失的乙肝病毒核心蛋白基因（HBV-C）,并对其进行DNA序列和蛋白质结构分析。方法通过PCR从1株乙型肝炎病毒中扩增得到发生长片段缺失的HBV-C基因,利用TA克隆将PCR产物克隆人pUCm—T载体并进行测序、同源性比较和蛋白质结构分析。结果PCR扩增出的HBV-C基因经序列分析表明长度为454bp,其核苷酸序列缺失了220—317bp之间的98个碱基,造成从74个氨基酸起发生移码突变。结论成功克隆发生长片段缺失的HBV-C基因,为表达及功能研究奠定了基础。     

APC11基因真核表达质粒构建及鉴定

目的克隆扩增APC11开放阅读框基因片段,构建其真核表达重组质粒,为后续研究其功能做准备。方法按照GenBank中人APC11序列设计引物,以HeLa细胞cDNA为模板,扩增出基因片段。该片段与真核表达载体pEGFP-C1连接,得到的重组质粒经双酶切和测序鉴定后用Western印迹检验表达。结果扩增片段长度为285bp,重组真核表达质粒经双酶切鉴定后测序鉴定正确。Western印迹证实pEGFP—C1-APC11在真核细胞内表达。结论成功克隆了APC11基因并构建了pEGFP—C1-APC11真核表达重组质粒,Western印迹证实其表达良好,对该基因功能的深入研究打下了坚实基础。     

人钠/碘同向转运体基因cDNA的克隆与序列测定

为研究人钠／碘同向转运体(hNIS)的生物学性能和用于肿瘤放射性碘治疗的可能性,运用反转录聚合酶链反应(RT—PCR)从人甲状腺组织总RNA中扩增出hNIS基因cDNA序列,将其克隆至pUCm-T载体中。序列分析证实克隆片段与献报道的hNIS基因cDNA序列完全一致,说明已成功克隆到hNIS基因cDNA。     

稻属NBS—LRR类基因的克隆及抗稻瘟病基因的表达

利用已克隆植物的R基因NBS序列中保守基序设计简并引物进行PCR扩增是克隆NBS有效的方法。从广东普通野生稻HLW028中克隆出3条序列,经同源性分析均为NBS,序列号为DQ272573～DQ272575。从NCBI中下载普通野生水稻和功能已知的水稻NBS—LRR类基因,与本试验所提交的NBS进行聚类分析。这些NBS可分为5大类,其中DQ272574是一个新的NBS基因类型。从野生水稻中克隆NBS基因存在P—loop、RNBS。A、kin-2、RNBS．B、RNBS—C和PLAL的基序。RT—PCR结果表明,培矮64中的Pikh的表达量比2种野生稻中高。从培矮64中扩增出1个完整读码框的cDNA。     

从人血液中克隆过氧化氢酶基因

目的从人血液中克隆过氧化氢酶基因。方法以新鲜的人血液为材料,提取全血RNA,运用RT—PCR方法扩增过氧化氢酶基因,构建pMDl8T／CAT克隆载体,并进行了不同来源过氧化氢酶的氨基酸序列同源分析。结果从人血液中成功扩增出过氧化氢酶基因,获得了重组载体PMD-18T／CAT,氨基酸序列分析的同源性达80％以上。结论从人血液中可以很方便地克隆出过氧化氢酶基因。     

人凝血因子Ⅶ cDNA基因的克隆与鉴定

目的:克隆并鉴定人凝血因子ⅦcDNA基因。方法:采用反转录聚合酶链反应(RT-PCR)的方法,从人胎肝总RNA中扩增人凝血因子ⅦcDNA基因,将其克隆入pGEM-T载体,对阳性克隆进行序列测定和分析。结果:经RT-PCR扩增和克隆,获得了人凝血因子ⅦcDNA基因,经序列分析表明,所克隆的基因序列正确。结论:本试验成功克隆了人凝血因子ⅦcDNA基因,为重组人凝血因子Ⅶ的研究奠定了基础。     

高粱可溶性酸性转化酶基因(SAI-1)PCR克隆方法

可溶性酸性转化酶(SAI)是蔗糖代谢途径中的关键酶,对植物生长发育起着至关重要的调节作用,研究简捷快速克隆可溶性酸性转化酶基因方法,对于育种材料和品种资源的基因分型具有重要意义。本研究通过已知的高粱可溶性酸性转化酶基因序列及高粱基因组中该基因序列片段,设计引物,比较了分段克隆、基因全长克隆、巢式PCR克隆等方法克隆高粱SAI-1基因的效果,结果表明,直接扩增全长,扩增产物极其不稳定且扩增产物纯化、连接,转化后得不到阳性克隆;采用均等分段克隆,前半段扩增产物纯化、连接转化后得不到阳性克隆,但后半段克隆成功;针对高粱基因组信息中SAI-1基因上游的未知序列部分设计引物,进行单独克隆(635 bp),再单独克隆其其余序列,两段序列拼接后得到SAI-1基因全长。序列分析发现,SAI-1前段635 bp的扩增片段GC含量高达69.6%,而其后GC含量急剧下降至30%以下,所以推测全长克隆、均等片段克隆以及巢式PCR克隆失败的原因可能是SAI-1基因中GC分布不均匀,克隆高粱SAI-1基因较为适宜的方法为利用2对引物进行不均等分段扩增克隆,前段PCR退火温度较后段高1℃。该方法将为其他研究人员提供有益参考。     

人RHD基因的克隆和鉴定

目的克隆人RHD基因,并对其进行鉴定。方法以RhD阳性志愿者骨髓为材料,用TRIzol试剂提取总RNA;设计、合成人RHD基因扩增引物,RT-PCR方法扩增RHD基因片段;T／A克隆后将其亚克隆人pET28a（＋）载体中,经酶切、PCR和测序对重组质粒进行鉴定。结果骨髓总RNA被成功提取;RT-PCR成功扩增出RHD基因片段,其大小与预期约509bp基本一致;T／A克隆后再将其亚克隆,通过酶切和PCR证明RHD基因成功亚克隆入pET28a（＋）载体中;基因测序结果比对显示,与已公布的RHD基因（GenBank登录号为NM016124）序列基本一致,同源性为98％。结论成功克隆了RHD基因,这将为进一步研究奠定基础。     

兔出血症病毒中国株衣壳蛋白基因的克隆和序列分析

应用RT—PCR技术,从兔出血症病毒中国分离株WX84中成功扩增出预期大小为1．7kb的特异性条带,将扩增产物提纯后克隆入pGEM^R—T载体,经转化、筛选及酶切鉴定后,获得了该株病毒衣壳蛋白基因的克隆,序列分析表明扩增的中国株BHD衣壳蛋白基因片段长度为1740bp,共编码580个氨基酸。该核酸序列与其它国家报道的多株BHDV序列相互间同源性高达98．2％一99．0％,其推导的氨基酸序列同源性也达98．3％--99．1％,为极度保守片段。     

日本血吸虫32kDa蛋白质基因在真核表达载体中的亚克隆

设计和合成特定寡核苷酸引物,TRIZOL提取日本血吸虫成虫RNA,RT-PCR法扩增日本血吸虫32kDa蛋白质(Sj32)基因编码序列,将扩增产物连接pGEM-T克隆载体,再亚克隆到真核表达载体pBKCMV中.结果RT-PCR法特异性扩增出Sj32编码基因片段,其大小约为1270bp,经双酶切、PCR鉴定表明所构建的质粒pGEM-Sj32和pBK-Sj32中含有目的基因.pBK-Sj32重组质粒的成功构建,为进一步表达Sj32及其在血吸虫病免疫诊断、免疫预防中的作用研究提供了条件.     

Molecular cloning of complementary DNA encoding one of the human pancreatic protease E isozymes

We have cloned a DNA from a human pancreatic cDNA library using a cloned rat pancreatic elastase 1 cDNA as a probe, and determined its nucleotide sequence. This cDNA contains a coding region of 810 nucleotides which encodes a 270-amino-acid protein. The deduced amino acid sequence shows less than 60% homologies with rat and porcine pancreatic elastase 1, although its substrate binding region is homologous with those of the above elastases 1. When this deduced amino acid sequence was compared with known amino acid sequences of pancreatic proteases other than elastases, it was found to contain an amino acid sequence which was highly homologous with the N-terminal amino acid sequence of porcine pancreatic protease E. We also purified human pancreatic protease E isozymes from human pancreatic juice, and determined their N-terminal amino acid sequences. One of the isozymes does not hydrolyze elastin but does hydrolyze a synthetic substrate. Endoglycosidase F digests glycoside bonds of the isozyme. These results suggest that the cDNA cloned by us corresponded to one of the human protease E isozymes.     

Porcine pyridoxal kinase: c-DNA cloning, expression and confirmation of its primary sequence

Porcine brain pyridoxal kinase has been cloned. A 1.2 kilo-based cDNA with a 966-base pair open reading frame was determined from a porcine brain cortex cDNA library using PCR technique. The DNA sequence was shown to encode a protein of 322 amino acid residues with a molecular mass of 35.4 kDa. The amino acid sequence deduced from the nucleotide sequence of the cDNA was shown to match the partial primary sequence of pyridoxal kinase. Expression of the cloned cDNA in E. coli has produced a protein which displays both pyridoxal kinase activity and immunoreactivity with monoclonal antibodies raised against natural enzyme from porcine brain. With respect to the physical properties, it is shown that the recombinant protein exhibits identical kinetic parameters with the pure enzyme from porcine brain. Although the primary sequence of porcine pyridoxal kinase has been shown to share 87% homology with the human enzyme, we have shown that the porcine enzyme carries an extra peptide of ten amino acid residues at the N-terminal domain.     

Isolation and expression in Escherichia coli of a cDNA clone encoding porcine pancreatic elastase

We have cloned a DNA that is complementary to the messenger RNA that encodes porcine pancreatic elastase 1 from pancreas using rat pancreatic elastase 1 cDNA as a probe. This complementary DNA contains the entire protein coding region of 798 nucleotides which encodes an elastase of 266 amino acids, and 22 and 136 nucleotides of the 5' and 3'-untranslated sequences. When this deduced amino acid sequence was compared with known amino acid sequences, a carboxy-terminal 240 amino acids long peptide was found to be identical with a mature form of porcine pancreatic elastase 1, except for two amino acids. The porcine enzyme contains the same number of amino acid residues as the rat enzyme, and their amino acid sequences are 85% homologous. Taking the above findings together, we conclude that the cloned cDNA encodes a mature enzyme of 240 amino acids including a leader and activation peptide of 26 amino acids. We expressed the cloned porcine pancreatic elastase 1 cDNA in E. coli as a lac-fused protein. The resulting fused protein showed enzymatic activity and immunoreactivity toward anti-elastase serum.     

The primary structure of porcine aminoacylase 1 deduced from cDNA sequence.

A cDNA encoding the complete amino acid sequence of aminoacylase 1 (N-acylamino acid aminohydrolase, ACY-1) [EC 3.5.1.14], a dimeric metalloprotein having two Zn2+ in the molecule, which catalyzes the deacylation of N-acylated L-amino acids except L-aspartic acid, has been isolated from porcine kidney lambda gt10 cDNA library and sequenced. From sequence analysis of the cDNA and the N- and C-terminal amino acid analyses of the purified protein, it is deduced that porcine kidney ACY-1 consists of two identical subunits (M(r) 45,260), each of which consists of a single chain of 406 amino acids with acetylalanine at the N-terminus. A cDNA encoding porcine liver ACY-1 was also cloned. The amino acid sequence deduced from the nucleotide sequence of the cDNA from porcine liver was identical to that deduced for porcine kidney ACY-1. Northern blot analysis suggested that ACY-1 is more highly expressed in kidney than in liver. Comparison of the amino acid sequence of porcine ACY-1 with those of other Zn2+-binding metalloenzymes showed no significant homologies in either the overall sequence or the consensus sequences for the metal binding sites. This indicates that ACY-1 is a new type of metalloprotein.     

Molecular cloning and expression in Escherichia coli of a cDNA encoding human pancreatic elastase 2

We have cloned a DNA that is complementary to the messenger RNA that encodes human pancreatic elastase 2 from a human pancreatic cDNA library using a cloned cDNA for rat pancreatic elastase 2 messenger RNA. This complementary DNA contains the entire protein coding region of 807 nucleotides which encodes preproelastase of 269 amino acids, and 4 and 82 nucleotides of the 5'- and 3'-untranslated sequences, respectively. When this deduced amino acid sequence was compared with known amino acid sequences it showed 82% homology with rat pancreatic elastase 2. This deduced sequence also contains a 16-amino-acid peptide identical with the N-terminal sequence determined for native human pancreatic proelastase 2. Taking the above findings together, we conclude that the cloned cDNA encodes a mature enzyme of 241 amino acids including 16 and 12 amino acids for a signal peptide and an activation peptide, respectively. Moreover, the predicted key amino acid residues involved in determining the substrate specificity of mammalian pancreatic elastase 2 are retained in the human enzyme. Cloned human pancreatic elastase 2 cDNA was expressed in E. coli as a mature and pro-form protein. Both resulting proteins showed immunoreactivity toward anti-elastase serum and enzymatic activity. We have also cloned and sequenced a porcine pancreatic elastase 2 cDNA.     

Cloning and characterization of chicken adipocyte fatty acid binding protein gene

Fatty acid binding proteins (FABPs) are members of a superfamily of lipid-binding proteins and occur intracellularly in vertebrates and invertebrates. This study was designed to clone and characterize the adipocyte fatty acid binding protein (A-FABP) gene in the chicken. PCR primers were designed according to mammalian A-FABP gene sequence to amplify partial cDNA of A-FABP gene from chicken adipose tissues, and the full length of the gene was cloned by 5'RACE and 3'RACE. Analysis of sequence showed that the cDNA of the chicken A-FABP gene was 74 and 73% homologous with porcine and human A-FABP gene, respectively. The similarity was 77, 28, and 23% at the predicted amino acid level with human A-FABP, human L-FABP, and human I-FABP, respectively. RT-PCR and Northern blot analysis indicated that the chicken A-FABP gene, similar to that of the mammal, is only expressed in fat tissues. This is the first report to identify and characterize A-FABP gene in the chicken.     

Molecular cloning and nucleotide sequence of rat lingual lipase cDNA.

Purified rat lingual lipase (EC3113), a glycoprotein of approximate molecular weight 52,000, was used to generate polyclonal antibodies which were able to recognise the denatured and deglycosylated enzyme. These immunoglobulins were used to screen a cDNA library prepared from mRNA isolated from the serous glands of rat tongue cloned in E. coli expression vectors. An almost full length cDNA clone was isolated and the nucleotide and predicted amino acid sequence obtained. Comparison with the N-terminal amino acid sequence of the purified enzyme confirmed the identity of the cDNA and indicated that there was a hydrophobic signal sequence of 18 residues. The amino acid sequence of mature rat lingual lipase consists of 377 residues and shares little homology with porcine pancreatic lipase apart from a short region containing a serine residue at an analogous position to the ser 152 of the porcine enzyme.