Validation of housekeeping genes as internal controls for studying the gene expression in Pyropia haitanensis(Bangiales, Rhodophyta) by quantitative real-time PCR

Pyropia haitanensis is an economically important mariculture crop in China and has a high research value for several life phenomena, for example environmental tolerance. To explore the mechanisms underlying these characteristics, gene expression has been investigated at the whole transcriptome level. Gene expression studies using quantitative real-time PCR should start by selecting an appropriate internal control gene; therefore, the absolute expression abundance of six housekeeping genes （18S rRNA （18S）, ubiquitin-conju-ating enzyme （UBC）, actin （ACT）, β-tubulin （TUB）, elongation factors 2 （EF2）, and glyceraldehyde-3-phos- phate dehydrogenase （GAPDH） examined by the quantitative real-time PCR in samples corresponding to different strains, life-cycle stages and abiotic stress treatments. Their expression stabilities were assessed by the comparative cycle threshold （Ct） method and by two different software packages： geNorm and NormFinder. The most stable housekeeping gene is UBC and the least stable housekeeping is GADPH. Thus, it is proposed that the most appropriate internal control gene for expression analyses in P. haitanensis is UBC. The results pave the way for further gene expression analyses of different aspects of P. haitanensis biology including different strains, life-history stages and abiotic stress responses.

Selection of Reference Genes for Gene Expression Analysis in Nilaparvata lugens with Different Levels of Virulence on Rice by Quantitative Real-Time PCR

The brown planthopper Nilaparvata lugens Stal （Homoptera： Delphacidae） can cause hopperburn by feeding on rice and also can transmit the grassy stunt disease. Resistant rice varieties have been developed, but several N. lugens strains can recover their virulence to these resistant rice varieties. In the present study, reference genes with stable expression levels in N. lugens populations showed different levels of virulence to susceptible and resistant rice varieties. The expression of six candidate reference genes in N. lugens feeding on susceptible and resistant rice varieties was analyzed. These genes were evaluated for their potential use in the analysis of differential gene expression. Polymerase chain reaction data was generated from N. lugens, including two different treatments （resistant or susceptible rice） and three virulent N. lugens populations. Three software programs （BestKeeper, Normfinder and geNorm） were used to assess the candidate reference genes. Both geNorm and Normfinder identified the genes 18S, E-ACT, E-TUB and a-TUB as the most stable reference genes. BestKeeper identified ETIF1 as the optimal reference gene with the least overall variation, whereas 18S and a-TUB were the second and third most stably expressed genes, respectively. Therefore, we concluded that the genes 18S and a-TUB were the most suitable reference genes in N. lugens. These results will facilitate future transcript profiling studies on N. lugens populations that show variation in virulence levels on different rice varieties.

Expression quantitative trait analyses to identify causal genetic variants for type 2 diabetes susceptibility

Type 2 diabetes(T2D) is a common metabolic disorder which is caused by multiple genetic perturbations affecting different biological pathways. Identifying genetic factors modulating the susceptibility of this complex heterogeneous metabolic phenotype in different ethnic and racial groups remains challenging. Despite recent success, the functional role of the T2D susceptibility variants implicated by genome-wide association studies(GWAS) remains largely unknown. Genetic dissection of transcript abundance or expression quantitative trait(eQTL) analysis unravels the genomic architecture of regulatory variants. Availability of eQTL information from tissues relevant for glucose homeostasis in humans opens a new avenue to prioritize GWASimplicated variants that may be involved in triggering a causal chain of events leading to T2D. In this article, we review the progress made in the field of eQTL research and knowledge gained from those studies in understanding transcription regulatory mechanisms in human subjects. We highlight several novel approaches that can integrate eQTL analysis with multiple layers of biological information to identify ethnic-specific causal variants and gene-environment interactions relevant to T2D pathogenesis. Finally, we discuss how the eQTL analysis mediated search for "missing heritability" may lead us to novel biological and molecular mechanisms involved in susceptibility to T2D.

Cloning and Prokaryotic Expression of FnBP Ligand Binding Gene of Staphylococcus aureus

[Objective] The study aimed to clone the FnBP ligand binding gene of Staphylococcus aureus and run prokaryotic expression by constructing a prokaryotic expression vector. [Method] The gene encoding FnBP ligand binding gene was amplified from S.aureus chromosomal DNA by PCR technique. After T-A cloning, plasmid pMD18- FnBP was constructed. pMD18- FnBP and pET28a(+)were digested by BamH Ⅰ and EcoR Ⅰ double enzymes, then the purified FnBP ligand binding gene was subcloned into the expression vector pET28a(+), and the prokaryotic expression vector pET28a-FnBP was thus constructed. The constructed plasmid pET28a-FnBP was transformed into Escherichia coli BL21(DE3) competent cells. The bacterium was induced by IPTG and the expressed products were analyzed by SDS-PAGE and Western blot. [Result] The gene fragment with the length of 370 bp was amplified by PCR approach. One approximately 30 kD exogenous protein was observed in SDS-PAGE analysis. Western blot analysis indicates the protein has antigenicity of S.aureus. [Conclusion] The FnBP ligand binding gene of S.aureus was successfully cloned and expressed in prokaryotic cells.

Cloning of Rabbit Bone Morphogenetic Protein 15 and Its Expression During in vitro Maturation of Rabbit Oocytes

Partial cDNA sequence of rabbit BMP15 was cloned by RT-PCR from rabbit ovaries, showing a similarity of 83%-90% with the BMP15 nucleotide sequences in humans, mice, ovine, sheep, cows and pigs. The expression of BMP15 in rabbit cumulus-oocyte complexs during oocytes in vitro maturation （IVM） was measured by fluorescent quantitative RT-PCR method. BMP 15 was expressed at low levels in immature oocytes and increased to the highest level at 16h of IVM, which coincides with the time of cumulus cell expansion, then declined slowly under IVM cultivation. The expression pattern of BMP 15 suggested that it might be important in cumulus expansion in rabbits.

Molecular Cloning and Expression of RSSG58 Gene in Rice Sperm Cells

Myosins, a large family of structurally diverse mechanoenzymes, which, upon interaction with actin filaments, convert energy from ATP hydrolysis into mechanical force, play an important role in male reproductive processes. In this study we report the rice ( Oryza sativa L.) RSSG58 gene, which was cloned from the cDNA library of rice sperm cells by using sperm cell mainly expression subtractive clone as probe. This gene encodes a putative 66.7 W polypeptide, which shows similarity to the myosin heavy chain of Arabidopsis thaliana, and consists of 579 amino acids with an isoelectric point (pI) of 4.885. RSSG58, which is a member of a divergent gene family, generates transcripts of 2 278 bp and 2 437 bp that differ only in their polyadenylation sites. Southern hybridization showed that RSSG58 has only one copy in rice genome and RSSG58 transcripts are most abundant in sperm cells, with two distinct signals. The RT-PCR analysis indicated that the transcriptions of the RSSG58 gene were various in the different development stages and tissues. The greatest accumulation of RSSG58 mRNA was detected in sperm cells, while weaker expression was detected in leaves, microspore mother cells, unicellular microspore pollen stage, two-cell stage pollens, mature pollens and pollinated ovaries. These results suggest that RSSG58 is especially abundantly expressed in rice sperm cells.

Cloning and Prokaryotic Expression of NS1 Gene of Porcine Parvovirus (PPV) SD1 Strain

[Objective] The research aimed to provide the theoretical basis for establishing a rapid diagnosis method for porcine parvovirus（PPV）. [ Method] One pair of primers were designed according to PPV genome sequences on GenBank website and the sequences of prokaryotic expression vector pET30a （ ＋ ） with multiple cloning sites. The whole sequence of NS1 gene in PPV SD1 strain was amplified by using PCR technology and the positive recombinant plasmid was analyzed by sequencing and homology comparison. The prokaryotic expression recombinant plasmid PET30a/NS1 was constructed to make its induction expression in Escherichia coll. [ Result] The target fragment with the length of 2 208 bp was obtained from PCR amplification. The nucleotide homologies between the cloned NS1 gene and the reported relevant PPV genes were from 97.3 % to 99.4 %, which indicated that NS1 gene had high conservation. But it had a 12-basepair successive deletion near the hydroxyl end. The cloned PPV NS1 gene was successfully expressed in prokaryotic cell, and its expression products existed mostly in inclusion bodies. [ Conclusion] The results of SDS-PAGE detection showed that the molecular weight of PPV NS1 protein was 86 KD.

Cloning and Expression of Conserved Sequences of cry Gene in E.coli Strain Rosetta(DE3)

[Objective] The aim was to clone the conserved sequences of cry gene and express them in Rosetta （DE3）. [Method] Specific primers were designed according to NCBI database information and the conserved sequences of cry gene were amplified by PCR from Bt transgenic cotton. Then recombinant plasmids were constructed and expressed in E. coil strain Rosetta （DE3）. Finally, the effects of different concentrations and inducing time of IPTG on the expression level of protein were investigated. [Result] Two conserved sequences （304 and 853 bp respectively） of cry gene were amplified. The result of SDS-PAGE confirmed that the recombinant plasmids pGEX-4t-I-304 and pGEX-4t-1-853 could express fusion proteins by IPTG induction and the molecular weight of protein products was 39 and 62.4 kDa respectively, which was in accordance with predicted result. The optimal protein ex- pression conditions were confirmed as induction with 0.15 mmol/L IPTG for 7 h. [Conclusion] This study prepared the ground for the further detection of Bt transgenic crops.

Cloning and Expression of Wheat Heat-shock Protein 60 (HSP60) Gene in E.coli

[Objective]The aim was to construct the wheat heat-shock protein 60 （HSP60） gene in prokaryotic expression vector and express HSP60 efficiently in E.coli. [Method]According to the wheat HSP60 gene sequence in GenBank,a pair of primers P1/P2 were designed and synthesized. The wheat HSP60 gene fragment was amplified from the wheat RNA by RT-PCR and inserted into bacterial expression vector of pGEX-4T-1. The construct of pGEX-4T-1-HSP60 was subsequently transformed into E.coli BL21. [Result]The construct of pGEX-4T-1-HSP60 was verified by restriction endonuclease digestion and sequenced. Compared with the sequences of wheat HSP60 genes in GenBank,homology accounted to 100%. Expression of the GST-HSP60 fusion protein was induced with IPTG. Its molecular weight was about 90 kD. The result was identified by electrophoresis of SDS-PAGE. Expression of the protein bands was consistent with the expected size. [Conclusion]The recombinant prokaryotic expression vector in pGEX-4T-1-HSP60 was constructed successfully and expressed stably in E.coli BL21. This will lay the foundation for further study on the functions of the protein and its mechanism.

Cloning and Expression of pilA Gene of Outer Membrane Protein of Haemophilus parasuis

[Objective] The aim was to clone and express the pilA gene of outer membrane protein of Haemophilus parasuis.[Method] The published pilA gene sequence of HPS was analyzed for primer synthesis,and the genome of serotype 5-type of HPS was used as template for PCR amplification of the pilA gene of HPS;the recombinant expression plasmid was constructed and transformed into E.coli BL21（DE3）after induced by IPTG.SDS-PAGE and Western blot analysis were then carried out.[Result] The molecular weight of expressed protein was consistent with the expected（43 kD）.[Conclusion] The results provided a foundation for the preparation of subunit vaccine and diagnostic reagents.

Cloning, Analysis and Prokaryotic Expression of DsSP Gene from Dunaliella salina

[Objective] The purpose of this study was to clone a starch phosphorylase gene from Dunaliella salina and to preliminarily analyze its basic properties and protein expression. [Method] RT-PCR and RACE （rapid amplification of cDNA ends） method was used for gene cloning; basic properties of the gene were analyzed using bioinformatics method; prokaryotic expression vector PGS21a-DsSP was constructed and transformed into E. coil BL21; the fusion protein was purified and detected by GST-SefinoseTM Kit and Western Blot, respectively. [Result] A starch phos-phorylase gene （GenBank accession No. KF061044） named DsSP was successfully isolated from D. salina. Basic properties, subcellular localization, secondary structure and tertiary structure of the protein were analyzed and predicted. The fusion protein was found in the supernatant and inclusion bodies. The supernatant protein was successfully purified. Western Blot analysis showed that the fusion protein was successfully expressed in E. coil BL21. [Conclusion] This study laid experimental foun- dation for further clarifying the function and mechanism of DsSP.

Cloning of Acetyl-CoA Carboxylase accD Subunit Gene from Brassica campestris and Effect of Its Expression on Oil Content

[Objective] This study aimed to clone accD gene from Brassica campestris （Yunnan small rapeseed） with different oil content and analyze the effect of accD gene expression level on rapeseed oil content. [Method] The accD gene encoding β-CT Ⅱsubunit of acetyl-CoA carboxylase was cloned from Yunnan small rapeseeds with different oil content. Then, sequence alignment and the influence upon seed oil content by the expression of accD gene were analyzed. [Result] There were a few base pair substitutes among the accD genes from different Yunnan small rapeseeds, and their homology was up to 98.6%. The expression of accD gene was increased with reproduction development, and reached peak in late-stage siliques. The seed oil content was positively influenced by the expression of accD gene in middle-stage and late-stage siliques. [Conclusion] This study provides a certain theoretical basis for illustrating the molecular mechanism about rapeseed oil content and breeding new high-oil rapeseed cultivars.

cDNA Cloning, Bioinformatic and Tissue-specific Expression Analysis of Porcine JARID1C Gene

Jumonji, AT-rich interactive domain 1C （JARID1C） protein belongs to the highly conserved ARID protein family, which is involved in chromatin remodeling and transcriptional regulation during cell growth, differentiation, and development. In humans, this gene plays a vital role in normal brain development and function. Using an in silico approach in combination with 5＇ rapid amplification of cDNA ends （5＇ RACE）, the full-length cDNA of JARIDIC （GenBank accession No. EF139241） from porcine ovary, which contains 5,908 bp nucleotides, with an open reading frame （ORF） of 4,548 bp, has been cloned. The putative porcine JARID 1C protein, which is located in the nucleus, encodes 1,516 amino acids with a molecular weight of 170 kDa and a pI of 5.44. Bioinformatic prediction indicates that the protein contains several conserved domains： a JmjN domain, an ARID domain, a JmjC domain, a C5HC2 zinc finger domain, and a PHD zinc finger domain. Similarity comparisons for nucleic and amino acid sequences reveal that the porcine JARID1C protein shares a high identity with its dog, mouse, rat, and human counterparts. The phylogenetic tree of the JARID1 subfamily proteins has been constructed to reveal the evolutionary relationship of various species. Real-time PCR analysis shows that the JARIDIC gene is expressed in various tissues, but at different levels. The expression levels of this gene are higher in the brain and gonad than in other tissues, suggesting that the JARID1C protein plays a role in porcine brain and gonad functions.

Molecular cloning and expression under abiotic stresses and hormones of the ethylene response factor Ⅶ gene FmRAP2.12 from Fraxinus mandshurica

RELATED TO AP2.12(RAP2.12)is one of the Ethylene Response Factors(ERF)transcription factor and plays a key role in controlling plant root bending and responding to multiple abiotic stresses including hypoxia stress.In this study,FmRAP2.12 gene was isolated and characterized from Fraxinus mandshurica Rupr.The open reading frame(ORF)of FmRAP2.12 was 1170 bp and encoded a protein of 389 amino acids.The conserved domains,three-dimensional phylogenetic relationship of FmRAP2.12 was also investigated.Quantitative real-time(qRT-PCR)analyzed the expression of FmRAP2.12 in different tissues.The expression level of FmRAP2.12 was highest in roots followed by leaves,and lowest in male flowers.Abiotic stress and hormone signal-induced expression was established using qRT-PCR.Salt stress induced FmRAP2.12 to a double peak pattern:the first peak value was at 6 h and the second at 72 h.Drought stress also induced FmRAP2.12 to a double peak pattern:the first at6 h and the second at 48 h.FmRAP2.12 was up-regulated after initiation of gibberellic acid(GA3)treatment,with a one peak pattern at 24 h.FmRAP2.12 may not respond to cold stress and Abscisic acid(ABA)treatment.The transient overexpression of FmRAP2.12 caused the up-expression of downstream key genes of abiotic stress response and gibberellin pathway.Our research reveals the molecular characteristic and expression patterns under abiotic stress and hormone condition of FmRAP2.12,providing support for the genetic improvement of F.mandshurica at a molecular level.

Cloning the Structure Genes and Expression the N Gene of Porcine Epidemic Diarrhea Virus DX

The structure genes spike(S) ,nucleocapsid(N) ,membrane(M) ,small membrane(sM) of a porcine epidemic diarrhea virus(PEDV) strain DX isolated in Gansu province,North-west of China,were cloned,sequenced and compared with published sequences of PEDV strains. The nucleotide sequences encoding the entire S,sM,M and N genes open reading frame(ORF) of DX were 4 152,231,681 and 1 326 bases long respectively. There were transcription regulatory sequences(TRSs) upstream of the initiator ATG of the S,N and M genes. The amino acids sequences of S,M and N contained 30,3 and 7 potential asparagine(N) -linked glycosylation sites. Homologous analysis and phylogenetic trees showed that DX had the closest relationship with strains LJB/06,JS-2004-2Z and CH/HLJH/06 that were also isolated from China and indicated the prevalence of some PEDV isolates in China were widespread since the JS-2004-2Z strain originated from the south of the China,and LJB/06 and CH/HLJH/06 were isolated from northeast China. The N gene was cloned using two primers which contained Nco I and BamH I restriction enzyme sites and subcloned into expression vector pET30a. The recombinant plasmid was then transformed into E.coli Rossta. SDS-PAGE showed there was a protein of about 55kDa as expected and Western blot indicated the N protein had biological activity.

Cloning and Expression Analysis of OsNADPH1 Gene from Rice in Drought Stress Response

An experiment was conducted to compare the mRNA expression difference in rice leaves and roots under drought stress and normal conditions us, ng Fluorescent Differential Display （FDD） method. One positive fragment was isolated by combination of the H. A. Yellow-PAGE （cont,~ined 0.1% H. A. Yellow） separation and macroarray screening methods. Compared to Arabidopsis thaliana NADPH oxidoreductase gene, it has 96% identity. The cDNA was 1423 bp, and contained a complete open reading frame of 1048 bp encoding a protein with 345 amino acid residues. Moreover, the gene expression level was higher under drought stress than that under normal conditions. The possible role of NADPH oxidoreductase gene under drought response was also discussed.

Gene Cloning and Expression Analysis of G Protein αq Subunit from Helicoverpa assulta (Guenée)

The cDNA encoding the G protein αq subunit was isolated from the antennae of Helicoverpa assulta （Guen6e） by reverse transcription polymerase chain reaction （RT-PCR） and named as HassGαq. Sequencing analysis showed that the fulllength of HassGαq open reading frame （ORF） is 1 062 bp, 353 amino acid residues are encoded. The predicted molecular weights （MW） and isoelectric point （PI） are 41.5 kD and 5.15, respectively. HassGαq gene was then constructed into expression vector pGEX-4T-2 for over expression in prokaryotic cells. The SDS-PAGE and Western blot analysis showed that induced by Isopropyl-β-D-Thiogalactoside （IPTG）, the GST-HassGαq fusion protein is expressed in Escherichia coil BL21, and its MW was found to be about 66 kD nearly equal to the predicted. In addition, RT-PCR analysis showed that the expressions of HassGαq are not tissue specific.

Cloning of Bile Salt Hydrolase Gene and Its Expression in Lactic Acid Bacteria

According to the sequence of the bile salt hydrolase （BSH） gene of Bifidobacterium and the restriction enzyme cutting sites of expression vector pNZ8148, primers were designed and the bile salt hydrolase （BSH） gene was gotten from Bacillus bifidus ATCC 29521 by PCR. BSH gene was inserted into lactic acid bacteria expression vector pNZ8148 to construct the recombinant pNZ8148-BSH. The recombinant pNZ8148-BSH was transferred into lactic acid bacteria NZ9000 with electrotransformation method. And the recombinant which could express BSH protein was obtained. It was identified by SDS-PAGE electrophoresis and activity verification. The result could provide a rationale reference for expressing BSH in lactic acid bacteria.

Molecular cloning and expression analysis of Crustin-like gene from Chinese shrimp Fenneropenaeus chinensis

A new member of antimicrobial protein genes of the Crustin family was cloned from haemocytes of the Chinese shrimp Fennero- penaeus chinensis by 3 ′and 5′ RACE. The full-length cDNA of Crustin-like gene contains a 390 bp open reading frame, encoding 130 amino acids. The deduced peptide contains a putative signal peptide of 17 amino acids and mature peptide of 113 amino acids. The molecular mass of the deduced mature peptide is 12. 3 ku. It is highly cationic with a theoretical isoelectric point of 8.5. The deduced amino acids sequence of this Crustin showed high homology with those of Penaeus （ Litopenaeus ） setferus. Northern blotting showed that the cloned Crustin gene was mainly expressed in haemocytes, gill, intestine, and RNA in situ hybridization indicated that the Crustin gene was constitutively expressed exclusively in haemocytes of these tissues. Capillary elec- trophoresis RT-PCR analysis showed that Crustin was up-regulated dramatically from 12 to 48 h after a brief decrease of mRNA during first 6 h in response to microbe infection. The level of Crustin mRNA began to restore at 72 h post-challenge. This indicated that Crustin gene might play an important role when shrimps are infected by bacterial pathogen.

Cloning of α-β fusion gene from Clostridium perfringens and its expression

AIM： To study the cloning of α-β fusion gene from Closindium perfringens and the immunogenidty of 0-6 fusion expression. METHODS： Cloning was accomplished after PCR amplification from strains NCTC64609 and C58-1 of the protective antigen genes of α-toxin and β-toxin. The fragment of the gene was cloned using plasmid pZCPAB. This fragment coded for the gene with the stable expression of α-β fusion gene binding. In order to verify the exact location of the α-β fusion gene, domain plasmids were constructed. The two genes were fused into expression vector pBV221. The expressed α-β fusion protein was identified by ELISA, SDS-PAGE, Western blotting and neutralization assay. RESULTS： The protective co-toxin gene （cpa906） and the β-toxin gene （cpb930） were obtained. The recombinant plasmid pZCPAB carrying α-β fusion gene was constructed and transformed into BL21（DE3）. The recombinant strain BL21（DE3）（pZCPAB） was obtained. After the recombinant strain BL21（DE3）（pZCPAB） was induced by 42℃, its expressed product was about 22.14% of total cellular protein at SDS-PAGE and thin-layer gel scanning analysis. Neutralization assay indicated that the antibody induced by immunization with α-βfusion protein could neutralize the toxicity of α-toxin and β-toxin. CONCLUSION： The obtained α-toxin and β-toxin genes are correct. The recombinant strain BL21（DE3）（pZCPAB） could produce α-β fusion protein. This protein can be used for immunization and is immunogenic. The antibody induced by immunization with α-β fusion protein could neutralize the toxicity of α-toxin and β-toxin.