scholarly journals Coordinated and High-Level Expression of Biosynthetic Pathway Genes Is Responsible for the Production of a Major Floral Scent Compound Methyl Benzoate in Hedychium coronarium

2021 ◽  
Vol 12 ◽  
Author(s):  
Yuechong Yue ◽  
Lan Wang ◽  
Rangcai Yu ◽  
Feng Chen ◽  
Jieling He ◽  
...  
Keyword(s):  
Gene Expression ◽  
Benzoic Acid ◽  
Methyl Salicylate ◽  
Biosynthetic Pathway ◽  
Floral Scent ◽  
Methyl Benzoate ◽  
High Level Expression ◽  
Developmentally Regulated ◽  
Hedychium Coronarium ◽  
High Level

Methyl benzoate is a constituent of floral scent profile of many flowering plants. However, its biosynthesis, particularly in monocots, is scarcely reported. The monocot Hedychium coronarium is a popular ornamental plant in tropical and subtropical regions partly for its intense and inviting fragrance, which is mainly determined by methyl benzoate and monoterpenes. Interestingly, several related Hedychium species lack floral scent. Here, we studied the molecular mechanism of methyl benzoate biosynthesis in H. coronarium. The emission of methyl benzoate in H. coronarium was found to be flower-specific and developmentally regulated. As such, seven candidate genes associated with methyl benzoate biosynthesis were identified from flower transcriptome of H. coronarium and isolated. Among them, HcBSMT1 and HcBSMT2 were demonstrated to catalyze the methylation of benzoic acid and salicylic acid to form methyl benzoate and methyl salicylate, respectively. Methyl salicylate is a minor constituent of H. coronarium floral scent. Kinetic analysis revealed that HcBSMT2 exhibits a 16.6-fold lower Km value for benzoic acid than HcBSMT1, indicating its dominant role for floral methyl benzoate formation. The seven genes associated with methyl benzoate biosynthesis exhibited flower-specific or flower-preferential expression that was developmentally regulated. The gene expression and correlation analysis suggests that HcCNL and HcBSMT2 play critical roles in the regulation of methyl benzoate biosynthesis. Comparison of emission and gene expression among four Hedychium species suggested that coordinated and high-level expression of biosynthetic pathway genes is responsible for the massive emission of floral methyl benzoate in H. coronarium. Our results provide new insights into the molecular mechanism for methyl benzoate biosynthesis in monocots and identify useful molecular targets for genetic modification of scent-related traits in Hedychium.

scholarly journals HOXA9 is required for survival in human MLL-rearranged acute leukemias

Blood ◽  
2009 ◽  
Vol 113 (11) ◽  
pp. 2375-2385 ◽  
Author(s):  
Joerg Faber ◽  
Andrei V. Krivtsov ◽  
Matthew C. Stubbs ◽  
Renee Wright ◽  
Tina N. Davis ◽  
...  
Keyword(s):  
Gene Expression ◽  
Expression Profiling ◽  
Therapeutic Option ◽  
Mixed Lineage Leukemia ◽  
High Level Expression ◽  
Acute Leukemias ◽  
Gene Expression Analyses ◽  
High Level ◽  
Novel Therapeutic

Leukemias that harbor translocations involving the mixed lineage leukemia gene (MLL) possess unique biologic characteristics and often have an unfavorable prognosis. Gene expression analyses demonstrate a distinct profile for MLL-rearranged leukemias with consistent high-level expression of select Homeobox genes, including HOXA9. Here, we investigated the effects of HOXA9 suppression in MLL-rearranged and MLL-germline leukemias using RNA interference. Gene expression profiling after HOXA9 suppression demonstrated co–down-regulation of a program highly expressed in human MLL-AML and murine MLL-leukemia stem cells, including HOXA10, MEIS1, PBX3, and MEF2C. We demonstrate that HOXA9 depletion in 17 human AML/ALL cell lines (7 MLL-rearranged, 10 MLL-germline) induces proliferation arrest and apoptosis specifically in MLL-rearranged cells (P = .007). Similarly, assessment of primary AMLs demonstrated that HOXA9 suppression induces apoptosis to a greater extent in MLL-rearranged samples (P = .01). Moreover, mice transplanted with HOXA9-depleted t(4;11) SEMK2 cells revealed a significantly lower leukemia burden, thus identifying a role for HOXA9 in leukemia survival in vivo. Our data indicate an important role for HOXA9 in human MLL-rearranged leukemias and suggest that targeting HOXA9 or downstream programs may be a novel therapeutic option.

scholarly journals Polychlorinated Biphenyl Rhizoremediation by Pseudomonas fluorescens F113 Derivatives, Using a Sinorhizobium meliloti nod System To Drive bph Gene Expression

2005 ◽  
Vol 71 (5) ◽  
pp. 2687-2694 ◽  
Author(s):  
Marta Villacieros ◽  
Clare Whelan ◽  
Martina Mackova ◽  
Jesper Molgaard ◽  
María Sánchez-Contreras ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Fluorescens ◽  
Sinorhizobium Meliloti ◽  
Polychlorinated Biphenyl ◽  
Expression System ◽  
Single Copy ◽  
Bacterial Strains ◽  
High Level Expression ◽  
High Level ◽  
Biodegradation Genes

ABSTRACT Rhizoremediation of organic chemicals requires high-level expression of biodegradation genes in bacterial strains that are excellent rhizosphere colonizers. Pseudomonas fluorescens F113 is a biocontrol strain that was shown to be an excellent colonizer of numerous plant rhizospheres, including alfalfa. Although a derivative of F113 expressing polychlorinated biphenyl (PCB) biodegradation genes (F113pcb) has been reported previously, this strain shows a low level of bph gene expression, limiting its rhizoremediation potential. Here, a high-level expression system was designed from rhizobial nod gene regulatory relays. Nod promoters were tested in strain F113 by using β-galactosidase transcriptional fusions. This analysis showed that nodbox 4 from Sinorhizobium meliloti has a high level of expression in F113 that is dependent on an intact nodD1 gene. A transcriptional fusion of a nodbox cassette containing the nodD1 gene and nodbox 4 fused to a gfp gene was expressed in the alfalfa rhizosphere. The bph operon from Burkholderia sp. strain LB400 was cloned under the control of the nodbox cassette and was inserted as a single copy into the genome of F113, generating strain F113L::1180. This new genetically modified strain has a high level of BphC activity and grows on biphenyl as a sole carbon and energy source at a growth rate that is more than three times higher than that of F113pcb. Degradation of PCBs 3, 4, 5, 17, and 25 was also much faster in F113L::1180 than in F113pcb. Finally, the modified strain cometabolized PCB congeners present in Delor103 better than strain LB400, the donor of the bph genes used.

scholarly journals Distinct Signaling Pathways from the Circadian Clock Participate in Regulation of Rhythmic Conidiospore Development in Neurospora crassa

2002 ◽  
Vol 1 (2) ◽  
pp. 273-280 ◽  
Author(s):  
Alejandro Correa ◽  
Deborah Bell-Pedersen
Keyword(s):  
Gene Expression ◽  
Circadian Clock ◽  
Neurospora Crassa ◽  
Mutant Strain ◽  
Specific Gene ◽  
Developmentally Regulated ◽  
Environmental Signals ◽  
Endogenous Clock ◽  
Environmental Induction ◽  
High Level

ABSTRACT Several different environmental signals can induce asexual spore development (conidiation) and expression of developmentally regulated genes in Neurospora crassa. However, under constant conditions, where no environmental cues for conidiation are present, the endogenous circadian clock in N. crassa promotes daily rhythms in expression of known developmental genes and of conidiation. We anticipated that the same pathway of gene regulation would be followed during clock-controlled conidiation and environmental induction of conidiation and that the circadian clock would need only to control the initial developmental switch. Previous experiments showed that high-level developmental induction of the clock-controlled genes eas (ccg-2) and ccg-1 requires the developmental regulatory proteins FL and ACON-2, respectively, and normal developmental induction of fl mRNA expression requires ACON-2. We demonstrate that the circadian clock regulates rhythmic fl gene expression and that fl rhythmicity requires ACON-2. However, we find that clock regulation of eas (ccg-2) is normal in an fl mutant strain and ccg-1 expression is rhythmic in an acon-2 mutant strain. Together, these data point to the endogenous clock and the environment following separate pathways to regulate conidiation-specific gene expression.

scholarly journals First report of a tetracycline-inducible gene expression system for mollicutes

Microbiology ◽  
2010 ◽  
Vol 156 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Marc Breton ◽  
Evelyne Sagné ◽  
Sybille Duret ◽  
Laure Béven ◽  
Christine Citti ◽  
...  
Keyword(s):  
Gene Expression ◽  
Expression System ◽  
Inducible Promoter ◽  
High Level Expression ◽  
Spiroplasma Citri ◽  
High Level ◽  
Tetr Repressor ◽  
Promoter System ◽  
Inducible Gene

Inducible promoter systems are powerful tools for studying gene function in prokaryotes but have never been shown to function in mollicutes. In this study we evaluated the efficacy of the tetracycline-inducible promoter Pxyl/tetO2 from Bacillus subtilis in controlling gene expression in two mollicutes, the plant pathogen Spiroplasma citri and the animal pathogen Mycoplasma agalactiae. An S. citri plasmid carrying the spiralin gene under the control of the xyl/tetO2 tetracycline-inducible promoter and the TetR repressor gene under the control of a constitutive spiroplasmal promoter was introduced into the spiralin-less S. citri mutant GII3-9a3. In the absence of tetracycline, expression of TetR almost completely abolished expression of spiralin from the xyl/tetO2 promoter. Adding tetracycline (>50 ng ml−1) to the medium induced high-level expression of spiralin. Interestingly, inducible expression of spiralin was also detected in vivo: in S. citri-infected leafhoppers fed on tetracycline-containing medium and in S. citri-infected plants watered with tetracycline. A similar construct was introduced into the M. agalactiae chromosome through transposition. Tetracycline-induced expression of spiralin proved the TetR-Pxyl/tetO2 system to be functional in the ruminant pathogen, suggesting that this tetracycline-inducible promoter system might be of general use in mollicutes.

scholarly journals The ontogeny of alpha-fetoprotein gene expression in the mouse gastrointestinal tract.

1990 ◽  
Vol 110 (4) ◽  
pp. 915-927 ◽  
Author(s):  
A L Tyner ◽  
R Godbout ◽  
R S Compton ◽  
S M Tilghman
Keyword(s):  
Gene Expression ◽  
Gastrointestinal Tract ◽  
Epithelial Cells ◽  
Dna Sequences ◽  
Colon Adenocarcinoma ◽  
Regulatory Elements ◽  
Alpha Fetoprotein ◽  
High Level Expression ◽  
High Level ◽  
Afp Mrna

The ontogeny of alpha-fetoprotein (AFP) gene expression has been examined in the fetal and adult mouse gastrointestinal tract. AFP mRNA constitutes approximately 0.1% of total mRNA in the fetal gut. The transcripts were localized by in situ hybridization to the epithelial cells lining the villi of the fetal gut. At birth, AFP mRNA declines rapidly to achieve low adult basal levels, which are not affected by different alleles of raf, a gene that determines the adult basal level of AFP mRNA in the liver. The basal level in the adult gut is the consequence of continued AFP transcription in a small number of enteroendocrine cells that are distributed infrequently on the villi. These cells were identified by double antibody staining with antibodies to chromogranin A, an enteroendocrine cell marker and AFP. Previous studies resulted in the generation of a line of transgenic mice containing an internally deleted AFP gene that was greatly overexpressed in the fetal gut. The basis for the inappropriately high level expression of the transgene was shown to be the consequence of very high levels of transcription in the epithelial cells of the villi rather than to expression in inappropriate cell types. The cis-acting DNA sequences required for expression of the AFP gene in the gut were investigated using Caco-2 cells, a human colon adenocarcinoma cell line. These experiments indicated that, with one exception, the regulatory elements required in both the promoter and enhancer regions of the gene coincided with those that are necessary for high level expression in the liver. The one exception was enhancer II, located 5 kbp of DNA upstream of the gene, which exhibited no activity in Caco-2 cells.

Application of anti-listerial bacteriocins: monitoring enterocin expression by multiplex relative reverse transcription–PCR

2012 ◽  
Vol 40 (6) ◽  
pp. 1544-1548 ◽  
Author(s):  
D. Ross Williams ◽  
Panagiotis Chanos
Keyword(s):  
Gene Expression ◽  
Reverse Transcription ◽  
Enterococcus Faecium ◽  
Growth Conditions ◽  
High Level Expression ◽  
Fermentation Conditions ◽  
Reverse Transcription Pcr ◽  
Food Borne ◽  
High Level

Listeriosis is a deadly food-borne disease, and its incidence may be limited through the biotechnological exploitation of a number of anti-listerial biocontrol agents. The most widely used of these agents are bacteriocins and the Class II enterocins are characterized by their activity against Listeria. Enterocins are primarily produced by enterococci, particularly Enterococcus faecium and many strains have been described, often encoding multiple bacteriocins. The use of these strains in food will require that they are free of virulence functions and that they exhibit a high level expression of anti-listerial enterocins in fermentation conditions. Multiplex relative RT (reverse transcription)–PCR is a technique that is useful in the discovery of advantageous expression characteristics among enterocin-producing strains. It allows the levels of individual enterocin gene expression to be monitored and determination of how expression is altered under different growth conditions.

scholarly journals Single-cell RNA-sequencing of Nicotiana attenuata petal cells reveals the entire biosynthetic pathway of a floral scent

2021 ◽  
Author(s):  
Moonyoung Kang ◽  
Yuri Choi ◽  
Hyeonjin Kim ◽  
Sang-Gyu Kim
Keyword(s):  
Gene Expression ◽  
Single Cell ◽  
Rna Sequencing ◽  
Biosynthetic Pathway ◽  
Floral Scent ◽  
Expression Profiles ◽  
Single Cells ◽  
Nicotiana Attenuata ◽  
Molecular Features ◽  
Single Cell Rna Sequencing

High-throughput single-cell RNA sequencing (scRNA-seq) identifies distinct cell populations based on cell-to-cell heterogeneity in gene expression. By examining the distribution of the density of gene expression profiles, the metabolic features of each cell population can be observed. Here, we employ the scRNA-seq technique to reveal the entire biosynthetic pathway of a flower volatile. The corolla (petals) of the wild tobacco Nicotiana attenuata emits a bouquet of scents that are composed mainly of benzylacetone (BA), a rare floral volatile. Protoplasts from the N. attenuata corolla were isolated at three different time points, and the transcript levels of >16,000 genes were analyzed in 3,756 single cells. We performed unsupervised clustering analysis to determine which cell clusters were involved in BA biosynthesis. The biosynthetic pathway of BA was uncovered by analyzing gene co-expression in scRNA-seq datasets and by silencing candidate genes in the corolla. In conclusion, the high-resolution spatiotemporal atlas of gene expression provided by scRNA-seq reveals the molecular features underlying cell-type-specific metabolism in a plant.

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