BMC Molecular Biology最新文献

Current research has shown that microRNAs (miRNAs) play vital roles in plant response to stress caused by heavy metals such as aluminum, arsenic, cadmium (Cd), and mercury. Cd has become one of the most hazardous pollutants in the environment. Maize can be a potential model to study phytoremediation of Cd-contaminated soil owing to its large biomass production. However, little is known about miRNAs as a response to Cd stress in maize.

To investigate the role of miRNAs in response to Cd stress, roots of seedlings of the inbred maize lines B73 and Mo17 were collected and treated with 200?mg/L CdCl₂·2.5 H₂O over different exposure times. Enzyme activities of superoxide dismutase and peroxidase were measured to confirm Cd stress. The expression of six candidate miRNAs and their targets were validated using quantitative real-time PCR (qRT-PCR) technology. In addition, the expression of Zma-miR171b was assessed using in situ hybridization.

Our results showed that miRNAs and their respective target genes were differentially expressed in maize seedling roots exposed to Cd stress. This research produced new insights into the molecular mechanism of miRNAs responsive to Cd stress in plants and sheds light on the latent roles of miRNAs in plants exposed to heavy metal stresses.

With the availability of genome sequences, gene expression analysis of jute has drawn considerable attention for understanding the regulatory mechanisms of fiber development and improving fiber quality. Gene expression profiles of a target gene can provide valuable clues towards the understanding of its biological function. Reverse transcription quantitative real-time PCR (qRT-PCR) is the best method for targeted gene expression analysis due to its sensitivity and reproducibility. However, calculating relative expression requires reference genes, which must be stable across various biological conditions. For this purposes, 11 prospective genes namely, 28S RNA, ACT7, CYP, EF1A, EF2, ETIF3E, GAPDH, PP2Ac, PTB, UBC2 and UBI1 were evaluated for their potential use as reference genes in jute.

The expression stabilities of eleven prospective genes were analyzed in various jute plant tissues, such as the root, stick, bark, leaf, flower, seed and fiber, as well as under abiotic (waterlogged, drought and salinity) and biotic stress (infestation with Macrophomina phaseolina) conditions with different time points. All 11 genes were variably expressed in different tissues and stress conditions. To find suitable reference genes in different sample sets, a comprehensive approach based on four statistical algorithms such as GeNorm, BestKeeper, NormFinder the ΔCt was used. The PP2Ac and EF2 genes were the most stably expressed across the different tissues. ACT7 and UBC2 were suitable reference genes under drought stress, and CYP and PP2Ac were the most appropriate after inoculation with Macrophomina phaseolina. Under salinity stress, PP2Ac and UBC2 were the best genes, and ACT7 and PP2Ac were the most suitable under waterlogged conditions.

Expression stability of reference genes from jute varied in different tissues and selected experimental conditions. Our results provide a valuable resource for the accurate normalization of gene expression experiments in fiber research for important bast fiber crops.

Small nucleolar RNAs (snoRNAs) function in guiding 2′-O-methylation and pseudouridylation of ribosomal RNAs (rRNAs) and small nuclear RNAs (snRNAs). In recent years, more and more snoRNAs have been found to play novel roles in mRNA regulation, such as pre-mRNA splicing or RNA editing. In our previous study, we found a silkworm C/D box snoRNA Bm-15 can interact with Notch receptor gene in vitro. To further study the function of Bm-15, we cloned its homolog Sf-15 from Spodoptera frugiperda and investigate the function of Sf-15 in Sf9 cells.

We showed that knocking down of Sf-15 can inhibit the proliferation, then induce apoptosis of insect S. frugiperda Sf9 cells, but the results were reversed when Sf-15 was overexpressed. De novo sequencing of transcriptome of Sf9 cells showed that the expression of 21 apoptosis-related genes were increased upon Sf-15 repression. Further analysis showed that a Ca²⁺-induced cell death pathway gene Cn (PPP3C, the serine/threonine-protein phosphatase 2B catalytic subunit), was significantly increased upon Sf-15 depression but decreased when Sf-15 was overexpressed, which indicated that Cn might be a potential target of Sf-15.

We conclude that C/D box snoRNA Sf-15 can participate in apoptosis through regulating the expression of Ca²⁺-induced cell death pathway gene Cn in Sf9 cells. This is the first time that we found snoRNAs exhibiting dual functions in insect, which reveals a novel layer of ncRNA modulation in cell growth and death.

Camels possess the characteristics of salt- and drought-resistances, due to the long-time adaption to the living environment in desert. The camel resistance research on transcriptome is rare and deficient, especially reabsorption in renal cortex. Non-coding RNAs are normally considered as the RNA molecules that are not translated into proteins, their current roles remain mostly in regulation of information flux from DNA to protein, further on normal life activities and diseases. In order to reveal the mysterious veil of the post-transcriptional regulation of ncRNAs in renal cortex for the first time as far as we know, we designed and carried out the experiment of salt stress and water-deprivation stress in camel.

By means of RNA-seq in renal cortex of Alxa Bactrian Camel (Camelus bactrianus), we identified certain significantly differential RNAs, including 4 novel lncRNAs, 11 miRNAs and 13 mRNAs under salt stress, 0 lncRNAs, 18 miRNAs and 14 mRNAs under water-deprivation stress. By data analysis, the response pathway of post-transcriptional regulation concerning salt and water-deprivation stresses was put forward, involving preventing sodium from entering the cell, purifying of water and compensating neutral amino acids by miR-193b, miR-542-5p interaction with SLC6A19 mRNA.

Based on the resistance-related lncRNAs, miRNAs, and mRNAs, we proposed the post-transcriptional regulation pathway to explain how camels respond to salt and water-deprivation stresses in the ncRNAs regulation level of renal cortex for the first time, thus hoping to provide a theoretical basis for therapy of disease that is similar to high blood pressure in humans.

The underlying mechanisms by which probiotic lactic acid bacteria (LAB) enhance the health of the consumer have not been fully elucidated. Verification of probiotic modes of action can be achieved by using single- or multiple-gene knockout analyses of bacterial mutants in in vitro or in vivo models. We developed a novel system based on an inducible toxin counter-selection system, allowing for rapid and efficient isolation of LAB integration or deletion mutants. The Lactococcus lactis nisin A inducible promoter was used for expression of the Escherichia coli mazF toxin gene as counter-selectable marker.

The flippase (FLP)/flippase recognition target (FRT) recombination system and an antisense RNA transcript were used to create markerless chromosomal gene integrations/deletions in LAB. Expression of NisR and NisK signalling proteins generated stable DNA integrations and deletions. Large sequences could be inserted or deleted in a series of steps, as demonstrated by insertion of the firefly bioluminescence gene and erythromycin resistance marker into the bacteriocin operons or adhesion genes of Lactobacillus plantarum 423 and Enterococcus mundtii ST4SA.

The system was useful in the construction of L. plantarum 423 and E. mundtii ST4SA bacteriocin and adhesion gene mutants. This provides the unique opportunity to study the role of specific probiotic LAB genes in complex environments using reverse genetics analysis. Although this work focuses on two probiotic LAB strains, L. plantarum 423 and E. mundtii ST4SA, the system developed could be adapted to most, if not all, LAB species.

Isatis indigotica, a traditional Chinese medicine, produces a variety of active ingredients. However, little is known about the key genes and corresponding expression profiling involved in the biosynthesis pathways of these ingredients. Quantitative real-time polymerase chain reaction (qRT-PCR) is a powerful, commonly-used method for gene expression analysis, but the accuracy of the quantitative data produced depends on the appropriate selection of reference genes.

In this study, the systematic analysis of the reference genes was performed for quantitative real-Time PCR normalization in I. indigotica. We selected nine candidate reference genes, including six traditional housekeeping genes (ACT, α-TUB, β-TUB, UBC, CYP, and EF1-α), and three newly stable internal control genes (MUB, TIP41, and RPL) from a transcriptome dataset of I. indigotica, and evaluated their expression stabilities in different tissues (root, stem, leaf, and petiole) and leaves exposed to three abiotic treatments (low-nitrogen, ABA, and MeJA) using geNorm, NormFinder, BestKeeper, and comprehensive RefFind algorithms. The results demonstrated that MUB and EF1-α were the two most stable reference genes for all samples. TIP41 as the optimal reference gene for low-nitrogen stress and MeJA treatment, while ACT had the highest ranking for ABA treatment and CYP was the most suitable for different tissues.

The results revealed that the selection and validation of appropriate reference genes for normalizing data is mandatory to acquire accurate quantification results. The necessity of specific internal control for specific conditions was also emphasized. Furthermore, this work will provide valuable information to enhance further research in gene function and molecular biology on I. indigotica and other related species.

Myocyte enhancer factor 2A (MEF2A) plays an important role in cell proliferation, differentiation and survival. Functional deletion or mutation in MEF2A predisposes individuals to cardiovascular disease mainly caused by vascular endothelial dysfunction. However, the effect of the inhibition of MEF2A expression on human coronary artery endothelial cells (HCAECs) is unclear. In this study, expression of MEF2A was inhibited by specific small interference RNA (siRNA), and changes in mRNA profiles in response to MEF2A knockdown were analyzed using an Agilent human mRNA array.

Silencing of MEF2A in HCAECs accelerated cell senescence and suppressed cell proliferation. Microarray analysis identified 962 differentially expressed genes (DEGs) between the MEF2A knockdown group and the negative control group. Annotation clustering analysis showed that the DEGs were preferentially enriched in gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to proliferation, development, survival, and inflammation. Furthermore, 61 of the 578 downregulated DEGs have at least one potential MEF2A binding site in the proximal promoter and were mostly enriched in the GO terms “reproduction” and “cardiovascular.” The protein–protein interaction network analyzed for the downregulated DEGs and the DEGs in the GO terms “cardiovascular” and “aging” revealed that PIK3CG, IL1B, IL8, and PRKCB were included in hot nodes, and the regulation of the longevity-associated gene PIK3CG by MEF2A has been verified at the protein level, suggesting that PIK3CG might play a key role in MEF2A knockdown induced HCAEC senescence.

MEF2A knockdown accelerates HCAEC senescence, and the underlying molecular mechanism may be involved in down-regulation of the genes related with cell proliferation, development, inflammation and survival, in which PIK3CG may play a key role.

A major cause of phytoplankton mortality is predation by zooplankton. Strategies to avoid grazers have probably played a major role in the evolution of phytoplankton and impacted bloom dynamics and trophic energy transport. Certain species of the genus Pseudo-nitzschia produce the neurotoxin, domoic acid (DA), as a response to the presence of copepod grazers, suggesting that DA is a defense compound. The biosynthesis of DA comprises fusion of two precursors, a C10 isoprenoid geranyl pyrophosphate and l-glutamate. Geranyl pyrophosphate (GPP) may derive from the mevalonate isoprenoid (MEV) pathway in the cytosol or from the methyl-erythritol phosphate (MEP) pathway in the plastid. l-glutamate is suggested to derive from the citric acid cycle. Fragilariopsis, a phylogenetically related but nontoxic genus of diatoms, does not appear to possess a?similar defense mechanism. We acquired information on genes involved in biosynthesis, precursor pathways and regulatory functions for DA production in the toxigenic Pseudo-nitzschia seriata, as well as genes involved in responses to grazers to resolve common responses for defense strategies in diatoms.

Several genes are expressed in cells of Pseudo-nitzschia when these are exposed to predator cues. No genes are expressed in Fragilariopsis when treated similarly, indicating that the two taxa have evolved different strategies to avoid predation. Genes involved in signal transduction indicate that Pseudo-nitzschia cells receive signals from copepods that transduce cascading molecular precursors leading to the formation of DA. Five out of seven genes in the MEP pathway for synthesis of GPP are upregulated, but none in the conventional MEV pathway. Five genes with known or suggested functions in later steps of DA formation are upregulated. We conclude that no gene regulation supports that l-glutamate derives from the citric acid cycle, and we suggest the proline metabolism to?be a downstream precursor.

Pseudo-nitzschia cells, but not Fragilariopsis, receive and respond to copepod cues. The cellular route for the C10 isoprenoid product for biosynthesis of DA arises from the MEP metabolic pathway and we suggest proline metabolism to be a downstream precursor for l-glutamate. We suggest 13 genes with unknown function to be involved in diatom responses to grazers.

Thrips tabaci is a severe pest of onion and cotton. Due to lack of information on its genome or transcriptome, not much is known about this insect at the molecular level. To initiate molecular studies in this insect, RNA was sequenced; de novo transcriptome assembly and analysis were performed. The RNAseq data was used to identify reference and RNAi pathway genes in this insect. Additionally, feeding RNAi was demonstrated in T. tabaci for the first time.

From the assembled transcriptome, 27,836 coding sequence (CDS) with an average size of 1236?bp per CDS were identified. About 85.4% of CDS identified showed positive Blast hits. The homologs of most of the core RNAi machinery genes were identified in this transcriptome. To select reference genes for reverse-transcriptase real-time quantitative PCR (RT-qPCR) experiments, 14 housekeeping genes were identified in the transcriptome and their expression was analyzed by (RT-qPCR). UbiCE in adult, 28s in nymphs and SOD under starvation stress were identified as the most stable reference genes for RT-qPCR. Feeding dsSNF7 and dsAQP caused 16.4- and 14.47-fold reduction in SNF7 and AQP mRNA levels respectively, when compared to their levels in dsGFP fed control insects. Feeding dsSNF7 or dsAQP also caused 62 and 72% mortality in T. tabaci. Interestingly, simultaneous feeding of dsRNAs targeting SNF7 or AQP and one of the RNAi pathway genes (Dicer-2/Aubergine/Staufen) resulted in a significant reduction in RNAi of target genes. These data suggest the existence of robust RNAi machinery in T. tabaci.

The current research is the first report of the assembled, analyzed and annotated RNAseq resource for T. tabaci, which may be used for future molecular studies in this insect. Reference genes validated across stages and starvation stress provides first-hand information on stable genes in T. tabaci. The information on RNAi machinery genes and significant knockdown of the target gene through dsRNA feeding in synthetic diet confirms the presence of efficient RNAi in this insect. These data provide a solid foundation for further research on developing RNAi as a method to manage this pest.

GTPase-activating proteins (GAPs) with a TBC (Tre-2/Bub2/Cdc16) domain architecture serve as negative regulators of Rab GTPases. The related crystal structure has been studied and reported by other members of our research group in 2017 (Chen et al. in Protein Sci 26(4):834–846, 2017). The protein crystal structure and sequencing data accession numbers in Protein structure database (PDB) are 5TUB (Shark TBC1D15 GAP) and 5TUC (Sus TBC1D15 GAP), respectively. In this paper, we analyzed the Rab-GAP specificity of TBC1D15 in the evolution and influence of key amino acid residue mutations on Rab-GAP activity.

Sequence alignment showed that five arginine residues of the TBC1D15-GAP domain are conserved among the species Sus/Mus/Homo but have been replaced by glycine or lysine in Shark. A fragment activity assay was conducted by altering the five residues of Shark TBC1D15-GAP to arginine, and the corresponding arginine in TBC1D15 GAP domains from Sus and Homo species were mutated to resemble Shark TBC1D15-GAP. Our data revealed that the residues of G28, K45, K119, K122 and K221 in the Shark TBC1D15-GAP domain had a key role in determining the specificity for Rab7 and Rab11. Mutation of the five residues significantly altered the Shark TBC1D15-GAP activity.

These results revealed that the substrate specificity of TBC1D15 has had different mechanisms across the evolution of species from lower-cartilaginous fish to higher mammals. Collectively, the data support a different mechanism of Shark TBC1D15-GAP in substrate selection, which provides a new idea for the development of Marine drugs.