钩吻脂氧合酶基因GeLOX1的鉴定及低温胁迫表达分析

近年来，钩吻（Gelsemium elegans）的药用和饲用价值日益凸显，但钩吻在生长过程中不耐低温，挖掘其低温响应基因，为钩吻的抗寒育种研究奠定基础。植物中，脂氧合酶（lipoxygenase, LOX）在种子老化、抗逆境胁迫等方面的生理生化过程中有重要影响。基于课题组构建的钩吻转录组数据库，挖掘响应低温胁迫的钩吻LOX基因，运用RT-PCR技术，从中克隆到一条GeLOX1的cNDA全长序列，对其进行生物信息学、亚细胞定位、基因表达、原核表达及平板胁迫等分析。结果显示，GeLOX1所编码蛋白的氨基酸长度为761 aa，蛋白相对分子质量为87.00 kD，预测为不稳定的亲水性蛋白，含有28个丝氨酸磷酸化位点，22个苏氨酸磷酸化位点和9个酪氨酸磷酸化位点。进化树分析结果表明，GeLOX1属于9-LOX家族的成员。亚细胞定位检测结果显示，GeLOX1蛋白定位于细胞质中。实时荧光定量PCR分析发现，GeLOX1在钩吻的根中高表达，且其在4℃低温胁迫下的表达量呈现下调的趋势。经原核表达诱导后，GeLOX1的重组蛋白在约111 kD处出现目标条带，且重组蛋白的积累量在诱导8 h时达到峰值。此外...     

光处理下粘虫头部组织定量PCR分析中内参基因的筛选

[目的]筛选不同光处理下粘虫Mythimna separata稳定表达的内参基因,为基因定量研究提供基础.[方法]以粘虫头部组织为材料,选取18s rRNA、EF-1α、β-actin、GAPDH和AK5种候选内参基因进行实时荧光定量PCR(qRT-PCR)分析,然后通过△Ct法,BestKeeper、GeNorrn、Normfinder和RefFinder软件对候选内参基因的稳定性进行分析;利用GeNorm软件进行基因配对差异分析,以判断内参基因的最适组合.[结果]5种候选内参基因的Ct值都处于15-28之间.4种软件对5个候选基因稳定性的分析结果存在一定差异.综合分析各种软件的分析结果,推荐粘虫成虫不同光处理条件下采用AK和GAPDH作为内参基因.[结论]根据特定试验体系选择合适的内参基因对于qRT-PCR定量结果的准确定和可靠性具有重要意义.本研究对后续粘虫在不同光处理条件下目标基因的准确定量具有重要意义.     

杂交兰实时荧光定量PCR内参基因的筛选

为了给杂交兰的基因功能表达和调控研究提供内参基因,本研究采取同源克隆方法和RT-PCR技术,以杂交兰‘黄金小神童’叶片为材料,分离杂交兰Ch18S r RNA、Ch28S r RNA、Ch ACT、Ch TUA、Ch TUB、Ch UBQ、Ch EF-1α和Chrpo B基因的片段,以10个不同品种杂交兰叶片及‘黄金小神童’花器官不同部位为材料,利用实时荧光定量PCR(Real-time quantitative PCR,q PCR)检测分析各引物的扩增效率和相对表达量,采用ge Norm、Norm Finder和Best Keeper软件对各个候选内参基因的表达稳定性进行分析,并通过研究杂交兰花器官不同部位Ch PDS基因的表达模式来验证筛选得到的内参基因的可靠性。结果显示,各引物扩增的片段长度分别为171 bp、148 bp、183 bp、146 bp、130 bp、147 bp、203 bp、139 bp,扩增效率分别为1.94、2.19、1.88、1.99、2.12、2.20、2.11、1.98。综合3个软件的评价结果发现,杂交兰不同品种叶片中最佳内参基因为Ch ACT,不同花器官部位中最稳定内参基因为Ch ACT、Ch TUB、Ch UBQ和Ch EF-1α;而对于实验中所有样品来说,内参基因稳定性最高的为Ch TUB;说明不同的实验条件下,所需的内参基因不同。Ch PDS基因相对表达水平分析结果证实了所筛选内参基因的可靠性,以Ch UBQ、Ch EF-1α、Ch TUB、Ch ACT及Ch UBQ和Ch EF-1α基因组合进行校正的Ch PDS基因的相对表达量均为花瓣唇瓣蕊柱。     

羽衣甘蓝不同组织及柱头发育实时荧光定量PCR内参基因的筛选

以羽衣甘蓝(Brassica oleracea var.acephala)S_(13-b)S_(13-b)自交不亲和系为试材,利用实时荧光定量PCR(qRTPCR)技术检测Actin、Cpi6、EF-1β、GAPDH、Tub-α3、Tub-α6、Ubc7候选内参基因在不同组织和5个不同发育时期柱头的表达情况,并运用ge Norm和Best Keeper软件统计分析候选内参基因的表达稳定性。在不同组织中,ge Norm软件统计分析的结果表明Tub-α6和EF-1β的表达较稳定;Best Keeper软件统计分析的结果表明Ubc7和Tub-α6的表达较稳定。在不同发育柱头中,ge Norm软件统计分析的结果表明Actin和Ubc7的表达较稳定;Best Keeper软件统计分析的结果表明EF-1β和Tub-α6的表达较稳定。以筛选到的内参基因Tub-α6和Actin,分别分析羽衣甘蓝柱头S-位点糖蛋白基因(SLG)在不同组织和不同发育时期柱头的表达水平,结果显示出SLG主要在柱头中表达,而且SLG在柱头发育成熟时期表达量达到最高。     

斑地锦RT-qPCR内参基因的筛选

实时荧光定量PCR(RT-qPCR)的前提条件之一是具有合适的内参基因。为筛选斑地锦(Euphorbia maculata)合适的RT-qPCR内参基因,该文利用同源克隆法克隆斑地锦GAPDH、EF-1α、act、UBQ、TUB-α、eIF-4A、CYP等基因片段,RT-qPCR检测7个候选内参基因在斑地锦不同生长期根、茎、叶和果实中的表达情况,并用geNorm、NormFinder和BestKeeper等生物学软件对各候选基因表达稳定性进行评价。结果表明:(1)克隆的GAPDH、EF-1α、act、UBQ、TUB-α、eIF-4A、CYP基因片段为729、808、753、422、233、656、313 bp,分别编码242、269、250、140、77、218、103个氨基酸,与其他植物相应氨基酸序列的最高同源性均在85%以上。(2)综合3个分析软件分析内参基因表达稳定性得出,表达稳定性排名为UBQ>EF-1α>TUB-α>eIF-4A>GAPDH>CYP>act。因此,可以选取UBQ作为斑地锦RT-qPCR分析的内参基因,用于不同生长期基因组织特异性表达研究。     

高速逆流色谱分离纯化钩吻中钩吻素甲

采用高速逆流色谱法,分别以正己烷-乙酸乙酯-无水乙醇-水(3∶3∶2∶3 V/V)和氯仿-甲醇-0.2 mol/L盐酸(4∶3∶1.5 V/V)为溶剂体系,从300 mg钩吻总碱中分离纯化出一种钩吻生物碱单体30.78 mg,高效液相色谱技术分析其质量分数为97.76%,核磁共振谱、质谱分析确证其为钩吻素甲;通过小鼠醋酸扭体法检测,表明钩吻总碱和钩吻素甲对小鼠均具有显著的镇痛活性。高速逆流色谱技术可高效分离纯化具有镇痛活性的钩吻素甲。     

钩吻(Gelsemium elegans)生物碱结构类型增补探讨

根据对亚洲钩吻(Gelsemium elegans)的化学研究结果,探讨将已知5种生物碱骨架类型扩展为9种,其中新增补并命名为Geleboline-type,Gelselegine-type,Gelsemamide-type,以及首次报道在亚洲钩吻中得到的Yohimbane-type类型。     

五龄飞蝗不同发育时间实时定量PCR内参基因的筛选

【目的】筛选5龄飞蝗不同发育时间的最适内参基因,为相关研究提供基础数据。【方法】本文选取β-肌动蛋白(β-actin)、延长因子(EF-1α)、3-磷酸甘油醛脱氢酶(GAPDH)、核糖体蛋白49(RP49)、α-微管蛋白(α-Tubulin)和18S核糖体RNA(18S rRNA)基因作为候选内参基因,运用实时定量PCR(qPCR)方法研究各基因在5龄飞蝗不同发育时间的相对表达量,用geNorm与Normfmder软件分析这6个基因表达稳定性。【结果】geNorm分析结果显示6个内参基因表达稳定度M值顺序为:β-actin(0.3720)>RP49(0.3750)>α-Tubulin(0.4030)>18S rRNA(0.4270)>EF-1α(0.4970)>GAPDH(0.6040)。M值越小表示基因表达稳定度越高,同时geNorm软件以标准化因子配对差异值(Pairwise variations)0.15默认为取舍值,由于V2/3=0.098<0.15,所以最适内参基因数目为2个。运用NormFinder软件也得出相似的结果。【结论】β-actin与RP49为5龄飞蝗不同发育时间的最适内参基因。     

菊叶薯蓣不同发育时期块茎内参基因的筛选

薯蓣皂苷元为重要的药物原料。为初步分析菊叶薯蓣(Dioscorea composita)块茎中薯蓣皂苷元合成关键基因的表达,筛选稳定表达的内参基因至关重要。根据已建立的菊叶薯蓣转录组数据库和已报道的传统内参基因,筛选出ubiquitin-conjugating enzyme E2(UBC7)、MMS ZWEI homologue 3(MMZ3)、tubulin beta-7(TUB7)、actin 1(ACT1)、glyceraldehyde-3-phosphate dehydrogenase C subunit 1(GAPC1)、elongation factor 1-alpha(EF-1α2)、cyclophilin 5(CYP5)、histone H2A2(H2A2)共8个候选内参基因,利用实时荧光定量PCR(qPCR)技术,结合Ge Norm、Norm Finder和Best Keeper三个统计学软件进行分析。结果表明,在菊叶薯蓣块茎不同发育过程中,TUB7和H2A2表达最稳定,为最佳内参基因。本研究为探究薯蓣皂苷元合成途径分子机理提供参考。     

梨小食心虫实时荧光定量PCR内参基因的筛选

【目的】本研究旨在探明梨小食心虫Grapholita molesta在不同发育阶段、成虫不同组织以及不同浓度的3种杀虫剂处理后成虫中稳定表达的内参基因,为后续对梨小食心虫目的基因表达的研究奠定基础。【方法】基于梨小食心虫转录组数据筛选10个候选内参基因(β-actin, 18S rRNA,β-tubulin,EF-1α,RPL13,RPL32,RSPL40,UBC7,α-tubulin和RPS20);通过实时荧光定量PCR(qRT-PCR)测定候选内参基因在梨小食心虫不同发育阶段(卵、1-5龄幼虫、蛹和成虫)、成虫不同组织(头、前肠、中肠、后肠、脂肪体、马氏管、精巢和卵巢)以及不同浓度的3种杀虫剂(阿维菌素：19.819, 72.897和179.663μg/mL;吡虫啉：17.638, 163.323和762.986μg/mL以及高效氯氟氰菊酯：33.791, 96.123和198.282μg/mL)通过玻璃管药膜法处理后成虫中的表达量;利用geNorm, NormFinder,ΔCt, BestKeeper和RefFinder对10个候选内参基因的表达稳定性进行评价。选择梨小食心虫细...     

Localization of HCH catabolic genes (lin genes) in Sphingobium indicum B90A

The locations of hexachlorocyclohexane (HCH) catabolic (lin) genes were investigated in HCH degrading sphingomonad, Sphingobium indicum B90A (that was isolated from India). Southern blot analysis revealed the presence of linA1, linC, linDER and linX (linX1 and linX2) on the plasmid DNA in Sphingobium indicum B90A.     

Vertebrate homeobox genes

In the former part of the review the principal available data aboutHox genes, their molecular organisation and their expression in vertebrate embryos, with particular emphasis for mammals, are briefly summarized.In the latter part we analysed the expression of four mouse homeobox genes related to twoDrosophila genes expressed in the developing head of the fly: Emx1 and Emx2, related toems, and Otx1 and Otx2, related tootd.     

Rhizobium nod genes are involved in the induction of two early nodulin genes in Vicia sativa root nodules

Nodulin gene expresison was studied in Vicia sativa (common vetch) root nodules induced by several Rhizobium and Agrobacterium strains. An Agrobacterium transconjugant containing a R. leguminosarum symplasmid instead of its Ti-plasmid, that was previously shown to form empty nodules on pea, induced nodules on Vicia roots in which nodule cells were infected with bacteria. In the Vicia nodules induced by this transconjugant, two so-called early nodulin genes were found to be expressed, whereas in the nodules formed on pea the expression of only one early nodulin gene was detected. In both cases the majority of the nodulin genes was not expressed.Apparently, an intracellular location of the bacteria is not sufficient for the induction of the majority of the nodulin genes. All nodulin genes were expressed in nodules induced by cured Rhizobium strains containing cosmid clones that have a 10 kb nod region of the sym-plasmid in common. Since in tumours no nodulin gene expression was found at all, the Agrobacterium chromosome does not contribute to the induction of nodulin genes. Therefore it is concluded that the signal for the induction of the expression of the two Vicia early nodulin genes is encoded by the nod-region, and the signal involved in the induction of all other nodulin genes has to be located outside the sym-plasmid, on the Rhizobium chromosome. The apparent difference in early nodulin gene expression between pea and Vicia is discussed in the light of the usefulness of Agrobacterium transconjugants in the study of nodulin gene expression.     

Mutations in somePolycomb group genes ofDrosophila interfere with regulation of segmentation genes

Mutations in severalPolycomb (Pc) group genes cause maternal-effect or zygotic segmentation defects, suggesting thatPc group genes may regulate the segmentation genes ofDrosophila. We show that individuals doubly heterozygous for mutations inpolyhomeotic and six otherPc group genes show gap, pair rule, and segment polarity segmentation defects. We examined double heterozygous combinations ofPc group and segmentation mutations for enhancement of adult and embryonic segmentation defects.Posterior sex combs andpolyhomeotic interact withKrüppel ² and enhance embryonic phenotypes ofhunchback andknirps, andpolyhomeotic enhanceseven-skipped. Surprisingly, flies carrying duplications ofextra sex combs (esc), that were heterozygous for mutations ofeven-skipped (eve), were extremely subvital. Embryos and surviving adults of this genotype showed strong segmentation defects in even-numbered segments. Antibody studies confirm that expression ofeve is suppressed by duplications ofesc. However,esc duplications have no effect on other gap or pair rule genes tested. To our knowledge, this is only the second triplo-abnormal phenotype associated withPc group genes. Duplications of nine otherPc group genes have no detectable effect oneve. Expression ofengrailed (en) was abnormal in the central nervous systems of mostPc group mutants. These results support a role forPc genes in regulation of some segmentation genes, and suggest thatesc may act differently from otherPc group genes.     

Expression of Frankia nif genes in nodules of Alnus glutinosa

Expression of Frankia genes involved in nitrogen fixation was studied in Alnus glutinosa nodules using the in situ hybridization technique. The results show that high level expression of nif genes does not occur immediately upon infection of cortical cells by Frankia. Also, only in the infected cells near the tips of the nodule lobes, nif genes are expressed at high levels. In the majority of infected cells, nif gene expression is rather low.     

Targeted disruption of chloroplast genes in Chlamydomonas reinhardtii.

Summary We have developed an efficient procedure for the disruption of Chlamydomonas chloroplast genes. Wild-type C. reinhardtii cells were bombarded with microprojectiles coated with a mixture of two plasmids, one encoding selectable, antibiotic-resistance mutations in the 16S ribosomal RNA gene and the other containing either the atpB or rbcL photosynthetic gene inactivated by an insertion of 0.48 kb of yeast DNA in the coding sequence. Antibiotic-resistant transformants were selected under conditions permissive for growth of nonphotosynthetic mutants. Approximately half of these transformants were initially heteroplasmic for copies of the disrupted atpB or rbcL genes integrated into the recipient chloroplast genome but still retained photosynthetic competence. A small fraction of the transformants (1.1% for atpB; 4.3% for rbcL) were nonphotosynthetic and homoplasmic for the disrupted gene at the time they were isolated. Single cell cloning of the initially heteroplasmic transformants also yielded nonphotosynthetic segregants that were homoplasmic for the disrupted gene. Polypeptide products of the disrupted atpB and rbcL genes could not be detected using immunoblotting techniques. We believe that any nonessential Chlamydomonas chloroplast gene, such as those involved in photosynthesis, should be amenable to gene disruption by cotransformation. The method should prove useful for the introduction of site-specific mutations into chloroplast genes and flanking regulatory sequences with a view to elucidating their function.     

A survey of introns in three genes of rotifers

Here we report on the occurrence and position of introns found in three genes of rotifers. A region of the gene for the TATA-box binding protein was examined in three species of Bdelloidea and one of Monogononta. There are two introns in both copies of this gene present in each of the three bdelloids examined – one at a position where introns occur in other eukaryotes and the other at a novel position; the monogonont has no introns in the region examined. A region of the gene encoding the 82 kD heat shock protein was examined in 10 species, with every rotifer class represented. Introns were found in only two species, both bdelloids: one of the species has an intron in all three copies of the gene; the other has an intron in only one of the three copies. Both introns occur at novel positions. The gene for triosephosphate isomerase was examined in one bdelloid. Both copies of the gene in this species contain introns, all at conserved positions: one copy contains five introns, the other copy three. These observations demonstrate the presence of introns in bdelloid rotifers, some in conserved positions, others apparently newly arisen during bdelloid evolution.     

Trans-sialidase genes expressed in mammalian forms of Trypanosoma cruzi evolved from ancestor genes expressed in insect forms of the parasite

The trans-sialidase of Trypanosoma cruzi mammalian forms transfers sialic acids from host's cell-surface glycoconjugates to acceptor molecules on parasite cell surface. To investigate the mechanism by which the mammalian stages of Trypanosoma cruzi have acquired their trans-sialidase, we compared the nucleotide and predicted amino acid sequences of trans-sialidase genes expressed in different developmental stages and strains of Trypanosoma cruzi with the sialidase gene of Trypanosoma rangeli and the sialidase genes of the prokaryotic genera Clostridium, Salmonella, and Actinomyces. The trans-sialidase gene products of Trypanosoma cruzi have a significant degree of structural and biochemical similarity to the sialidases found in bacteria and viruses, which would hint that horizontal gene transfer occurred in Trypanosome cruzi trans-sialidase evolutionary history. The comparison of inferred gene trees with species trees suggests that the genes encoding the T. cruzi trans-sialidase of mammalian forms might be derived from genes expressed in the insect forms of the genus Trypanosome. The branching order of trees inferred from T. cruzi trans-sialidase sequences, the sialidase from Trypanosoma rangeli, and bacterial sialidases parallels the expected branching order of the species and suggests that the divergence times of these sequences are remarkably long. Therefore, a vertical inheritance from a hypothetical eukaryotic trans-sialidase gene expressed in insect forms of trypanosomes is more likely to have occurred than the horizontal gene transfer from bacteria, and thus explains the presence of this enzyme in the mammalian infective forms of Trypanosoma cruzi.Correspondence to: M.R.S. Briones     

Hox genes in the echiuroid Urechis unicinctus

An echiuroid species, Urechis unicinctus, was surveyed for Hox genes using polymerase chain reaction with homeobox-specific degenerate primers. We identified nine distinct homeodomain-containing gene fragments. These nine fragments were classified by comparative analysis. This analysis revealed that this echiuroid possessed at least three Hox genes from the anterior group, five from the central group, and one from the posterior group.