Current Practices for Reference Gene Selection in RT-qPCR of Aspergillus: Outlook and Recommendations for the Future

Aspergillus is a genus of filamentous fungi with vast geographic and ecological distributions. Species within this genus are clinically, agriculturally and biotechnologically relevant, leading to increasing interest in elucidating gene expression dynamics of key metabolic and physiological processes. Reverse-transcription quantitative Polymerase Chain Reaction (RT-qPCR) is a sensitive and specific method of quantifying gene expression. A crucial step for comparing RT-qPCR results between strains and experimental conditions is normalisation to experimentally validated reference gene(s). In this review, we provide a critical analysis of current reference gene selection and validation practices for RT-qPCR gene expression analyses of Aspergillus. Of 90 primary research articles obtained through our PubMed query, 17 experimentally validated the reference gene(s) used. Twenty reference genes were used across the 90 studies, with beta-tubulin being the most used reference gene, followed by actin, 18S rRNA and glyceraldehyde 3-phosphate dehydrogenase. Sixteen of the 90 studies used multiple reference genes for normalisation. Failing to experimentally validate the stability of reference genes can lead to conflicting results, as was the case for four studies. Overall, our review highlights the need to experimentally validate reference genes in RT-qPCR studies of Aspergillus.

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Reference Gene Selection for Normalizing Gene Expression in Ips Sexdentatus (Coleoptera: Curculionidae: Scolytinae) Under Different Experimental Conditions

Frontiers in Physiology ◽

10.3389/fphys.2021.752768 ◽

2021 ◽

Vol 12 ◽

Author(s):

Gothandapani Sellamuthu ◽

Shan Amin ◽

Jan Bílý ◽

Jirí Synek ◽

Roman Modlinger ◽

...

Keyword(s):

Gene Expression ◽

Reference Gene ◽

Expression Analysis ◽

Reference Genes ◽

Gene Expression Analysis ◽

Gene Selection ◽

Experimental Conditions ◽

Tissue Specific ◽

Reference Gene Selection ◽

Ips Sexdentatus

Ips sexdentatus (Coleoptera: Curculionidae: Scolytinae) is one of the most destructive and economically important forest pests. A better understanding of molecular mechanisms underlying its adaptation to toxic host compounds may unleash the potential for future management of this pest. Gene expression studies could be considered as one of the key experimental approaches for such purposes. A suitable reference gene selection is fundamental for quantitative gene expression analysis and functional genomics studies in I. sexdentatus. Twelve commonly used reference genes in Coleopterans were screened under different experimental conditions to obtain accurate and reliable normalization of gene expression data. The majority of the 12 reference genes showed a relatively stable expression pattern among developmental stages, tissue-specific, and sex-specific stages; however, some variabilities were observed during varied temperature incubation. Under developmental conditions, the Tubulin beta-1 chain (β-Tubulin) was the most stable reference gene, followed by translation elongation factor (eEF2) and ribosomal protein S3 (RPS3). In sex-specific conditions, RPS3, β-Tubulin, and eEF2 were the most stable reference genes. In contrast, different sets of genes were shown higher stability in terms of expression under tissue-specific conditions, i.e., RPS3 and eEF2 in head tissue, V-ATPase-A and eEF2 in the fat body, V-ATPase-A and eEF2 in the gut. Under varied temperatures, β-Tubulin and V-ATPase-A were most stable, whereas ubiquitin (UbiQ) and V-ATPase-A displayed the highest expression stability after Juvenile Hormone III treatment. The findings were validated further using real-time quantitative reverse transcription PCR (RT-qPCR)-based target gene expression analysis. Nevertheless, the present study delivers a catalog of reference genes under varied experimental conditions for the coleopteran forest pest I. sexdentatus and paves the way for future gene expression and functional genomic studies on this species.

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Selection of the Reference Gene for Expression Normalization in Papaver somniferum L. under Abiotic Stress and Hormone Treatment

Genes ◽

10.3390/genes11020124 ◽

2020 ◽

Vol 11 (2) ◽

pp. 124 ◽

Cited By ~ 1

Author(s):

Zhaoping Zhang ◽

Changjian Li ◽

Junqing Zhang ◽

Fang Chen ◽

Yongfu Gong ◽

...

Keyword(s):

Gene Expression ◽

Reference Gene ◽

Reference Genes ◽

Gene Selection ◽

Quantitative Polymerase Chain Reaction ◽

Elongation Factor ◽

Papaver Somniferum ◽

Protein Subunit ◽

Experimental Conditions ◽

Analgesic Drugs

Papaver somniferum L. is an important medical plant that produces analgesic drugs used for the pain caused by cancers and surgeries. Recent studies have focused on the expression genes involved in analgesic drugs biosynthesis, and the real-time quantitative polymerase chain reaction (RT-qPCR) technique is the main strategy. However, no reference genes have been reported for gene expression normalization in P. somniferum. Herein, nine reference genes (actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), cyclophilin 2 (CYP2), elongation factor 1-alpha (EF-1α), glyceraldehyde-3-phosphate dehydrogenase 2, cytosolic (GAPC2), nuclear cap-binding protein subunit 2 (NCBP2), protein phosphatase 2A (PP2A), TIP41-like protein (TIP41), and tubulin beta chain (TUB)) of P. somniferum were selected and analyzed under five different treatments (cold, drought, salt, heavy metal, and hormone stress). Then, BestKeeper, NormFinder, geNorm, and RefFinder were employed to analyze their gene expression stability. The results reveal that NCBP2 is the most stable reference gene under various experimental conditions. The work described here is the first report regarding on reference gene selection in P. somniferum, which could be used for the accurate normalization of the gene expression involved in analgesic drug biosynthesis.

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Reference gene selection and evaluation for expression analysis using qRT-PCR in Galeruca daurica (Joannis)

Bulletin of Entomological Research ◽

10.1017/s0007485316000948 ◽

2016 ◽

Vol 107 (3) ◽

pp. 359-368 ◽

Cited By ~ 12

Author(s):

Y. Tan ◽

X.-R. Zhou ◽

B.-P. Pang

Keyword(s):

Reference Gene ◽

Reference Genes ◽

Target Genes ◽

Gene Selection ◽

Developmental Stages ◽

Pcr Analysis ◽

Experimental Conditions ◽

Reference Gene Selection ◽

Functional Studies ◽

Qrt Pcr

AbstractQuantitative real-time PCR (qRT-PCR) has been used extensively to analyze gene expression and decipher gene function. To obtain the optimal and stable normalization factors for qRT-PCR, selection and validation of reference genes should be conducted in diverse conditions. In insects, more and more studies confirmed the necessity and importance of reference gene selection. In this study, eight traditionally used reference genes in Galeruca daurica (Joannis) were assessed, using qRT-PCR, for suitability as normalization genes under different experimental conditions using four statistical programs: geNorm, Normfinder, BestKeeper and the comparative ΔCt method. The genes were ranked from the most stable to the least stable using RefFinder. The optimal suite of recommended reference genes was as follows: succinate dehydrogenase (SDHA) and tubulin-alpha (TUB-α) for temperature-treated larvae; ribosomal protein L32, SDHA and glutathione S-transferase were best for all developmental stages; ACT and TUB-α for male and female adults; SDHA and TUB-α were relatively stable and expressed in different tissues, both diapause and non-diapause adults. Reference gene evaluation was validated using expression of two target genes: the P450 CYP6 gene and the heat shock protein gene Hsp70. These results confirm the importance of custom reference gene selection when studies are conducted under diverse experimental conditions. A standardized qRT-PCR analysis procedure for gene functional studies is provided that could be useful in studies on other insect species.

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Identification and Validation of Reference Genes for Gene Expression Analysis in Different Development Stages of Amylostereum areolatum

Frontiers in Microbiology ◽

10.3389/fmicb.2021.827241 ◽

2022 ◽

Vol 12 ◽

Author(s):

Ningning Fu ◽

Jiaxing Li ◽

Ming Wang ◽

Lili Ren ◽

Shixiang Zong ◽

...

Keyword(s):

Gene Expression ◽

Reference Genes ◽

Growth And Development ◽

Target Genes ◽

Quantitative Polymerase Chain Reaction ◽

Growth Stages ◽

Experimental Conditions ◽

Development Stages ◽

Symbiotic Fungus ◽

The Stability

A strict relationship exists between the Sirex noctilio and the Amylostereum areolatum, which is carried and spread by its partner. The growth and development of this symbiotic fungus is key to complete the life history of the Sirex woodwasp. Real-time quantitative polymerase chain reaction (RT-qPCR) is used to measure gene expression in samples of A. areolatum at different growth stages and explore the key genes and pathways involved in the growth and development of this symbiotic fungus. To obtain accurate RT-qPCR data, target genes need to be normalized by reference genes that are stably expressed under specific experimental conditions. In our study, the stability of 10 candidate reference genes in symbiotic fungal samples at different growth and development stages was evaluated using geNorm, NormFinder, BestKeeper, delta Ct methods, and RefFinder. Meanwhile, laccase1 was used to validate the stability of the selected reference gene. Under the experimental conditions of this study, p450, CYP, and γ-TUB were identified as suitable reference genes. This work is the first to systematically evaluate the reference genes for RT-qPCR results normalization during the growth of this symbiotic fungus, which lays a foundation for further gene expression experiments and understanding the symbiotic relationship and mechanism between S. noctilio and A. areolatum.

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Reference Gene Selection for qPCR Normalization ofKosteletzkya virginicaunder Salt Stress

BioMed Research International ◽

10.1155/2015/823806 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 8

Author(s):

Xiaoli Tang ◽

Hongyan Wang ◽

Chuyang Shao ◽

Hongbo Shao

Keyword(s):

Gene Expression ◽

Reference Gene ◽

Reference Genes ◽

Gene Selection ◽

Expression Profiles ◽

Elongation Factor ◽

Gene Expression Profiles ◽

Stable Reference Gene ◽

Experimental Conditions ◽

Suitable Reference

Kosteletzkya virginica(L.) is a newly introduced perennial halophytic plant. Presently, reverse transcription quantitative real-time PCR (qPCR) is regarded as the best choice for analyzing gene expression and its accuracy mainly depends on the reference genes which are used for gene expression normalization. In this study, we employed qPCR to select the most stable reference gene inK. virginicawhich showed stable expression profiles under our experimental conditions. The candidate reference genes were 18S ribosomal RNA (18SrRNA),β-actin (ACT),α-tubulin (TUA), and elongation factor (EF). We tracked the gene expression profiles of the candidate genes and analyzed their stabilities through BestKeeper, geNorm, and NormFinder software programs. The results of the three programs were identical and18SrRNAwas assessed to be the most stable reference gene in this study. However,TUAwas identified to be the most unstable. Our study proved again that the traditional reference genes indeed displayed a certain degree of variations under given experimental conditions. Importantly, our research also provides guidance for selecting most suitable reference genes and lays the foundation for further studies inK. virginica.

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Evaluation of Candidate Reference Genes Stability for Gene Expression Analysis by Reverse Transcription QPCR in Clostridium Perfringens

10.21203/rs.3.rs-1108435/v1 ◽

2021 ◽

Author(s):

Michele Williams ◽

Mostafa Ghanem

Keyword(s):

Gene Expression ◽

Clostridium Perfringens ◽

Reference Gene ◽

Reverse Transcription ◽

Reference Genes ◽

Quantitative Polymerase Chain Reaction ◽

Toxin Gene ◽

Rrna Gene ◽

Experimental Conditions ◽

Toxin Gene Expression

Abstract Identification of stable reference genes for normalization purposes is necessary for obtaining reliable and accurate results of reverse transcription quantitative polymerase chain reaction (RT-qPCR) analyses. To our knowledge, no reference gene(s) have been validated for this purpose in Clostridium perfringens. In this study, the expression profile of ten candidate reference genes from three strains of C. perfringens were assessed for stability under various experimental conditions using geNorm in qbase+. These stability rankings were then compared to stability assessments evaluated by BestKeeper, NormFinder, delta Ct, and RefFinder algorithms. When comparing all the analyses; gyrA, ftsZ, and recA were identified within the most stable genes under the different experimental conditions and were further tested as a set of reference genes for normalization of alpha toxin gene expression over a 22-hour period. Depending on the condition, rpoA and rho might also be suitable to include as part of the reference set. Although commonly used for the purpose of normalizing RT-qPCR data, the 16S rRNA gene (rrs) was found to be an unsuitable gene to be used as a reference. This work provides a framework for the selection of a suitable stable reference gene set for data normalization of C. perfringens gene expression.

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Selection and Validation of Suitable Reference Genes for RT-qPCR Analysis in Bursaphelenchus Xylophilus

10.21203/rs.3.rs-270905/v1 ◽

2021 ◽

Author(s):

Yaning Liu ◽

Jiao Zhou ◽

Hongxia Zhang ◽

Faheem Ahmad ◽

Jianting Fan ◽

...

Keyword(s):

Gene Expression ◽

Reference Genes ◽

Gene Selection ◽

Developmental Stages ◽

Genetic Research ◽

Bursaphelenchus Xylophilus ◽

Stable Gene ◽

Pinewood Nematode ◽

Experimental Conditions ◽

The Stability

Abstract Quantitative reverse transcription polymerase chain reaction (RT-qPCR) is a powerful technique for studying gene expression, and it is widely used in molecular biology and genetic research. The key to quantitative accuracy depends on the stability of the reference genes used for data normalization under different experimental conditions. The pinewood nematode (PWN; Bursaphelenchus xylophilus) is the causal agent of a devastating disease, the pine wood disease (PWD), demanding extensive and prompt research to understand the molecular mechanism of PWD, but the identification of reference PWN genes for standardized RT-qPCR has not been reported yet. In this study, we have analyzed eight candidate reference genes of PWN under different temperature conditions and at different developmental stages. Delta Ct method, GeNorm, NormFinder, BestKeeper and RefFinder algorithms were used to evaluate the expression stability of these genes. 18SrRNA and HIS were selected for gene expression research under temperature treatments, while EF1γ and 18SrRNA for gene expression studies across different developmental stages. In general, the results indicate that 18SrRNA is the most stable gene for RT-qPCR under different conditions. Finally, we use arginine kinase gene (AK) in different temperature and heat shock protein 90 (HSP90) in different developmental stages to confirm the stability of expression. The systematic analysis of qRT-PCR reference gene selection of B. xylophilus will be helpful for future functional analysis and exploration of genetic resources of B. xylophilus.

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Evaluation of reference genes for gene expression studies in pig muscle tissue by real-time PCR

Czech Journal of Animal Science ◽

10.17221/1428-cjas ◽

2011 ◽

Vol 56 (No. 5) ◽

pp. 213-216 ◽

Cited By ~ 2

Author(s):

M. Nesvadbová ◽

A. Knoll

Keyword(s):

Gene Expression ◽

Real Time ◽

Reference Gene ◽

Muscle Tissue ◽

Reference Genes ◽

Expression Profiles ◽

Quantitative Polymerase Chain Reaction ◽

Expression Studies ◽

Gene Expression Studies ◽

The Stability

The selection of reference genes is essential for gene expression studies when using a real-time quantitative polymerase chain reaction (PCR). Reference gene selection should be performed for each experiment because the gene expression level may be changed in different experimental conditions. In this study, the stability of mRNA expression was determined for seven genes: HPRT1, RPS18, NACA, TBP, TAF4B, RPL32 and OAZ1. The stability of these reference genes was investigated in the skeletal muscle tissue of pig foetuses, piglets and adult pigs using real-time quantitative PCR and SYBR green chemistry. The expression of stability of the used reference genes was calculated using the geNorm application. Different gene expression profiles among the age categories of pigs were found out. RPS18 has been identified as the gene with the most stable expression in the muscle tissue of all pig age categories. HPRT1 and RPL32 were found to have the highest stability in piglets and adult pigs, and in foetuses and adults pigs, respectively. The newly used reference gene, TAF4B, reached the highest expression stability in piglets.

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Selection and validation of reference genes by RT-qPCR under photoperiodic induction of flowering in sugarcane (Saccharum spp.)

Scientific Reports ◽

10.1038/s41598-021-83918-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Paulo H. da Silva Santos ◽

João R. Vieira Manechini ◽

Michael S. Brito ◽

Elisson Romanel ◽

Renato Vicentini ◽

...

Keyword(s):

Gene Expression ◽

Reference Gene ◽

Reference Genes ◽

Target Genes ◽

Floral Induction ◽

Photoperiodic Induction ◽

Experimental Conditions ◽

Wide Range ◽

The Stability ◽

Stability And Consistency

AbstractAlthough reference genes have previously been used in the expression analysis of genes involved in sugarcane flowering they had not been experimentally validated for stability and consistency of expression between different samples over a wide range of experimental conditions. Here we report the analysis of candidate reference genes in different tissue types, at different temporal time-points, in both short and long day photoperiodic treatments. The stability of the candidate reference genes in all conditions was evaluated with NormFinder, BestKeeper, and RefFinder algorithms that complement each other for a more robust analysis. As the Normfinder algorithm was more appropriate for our experimental conditions, greater emphasis was placed on Normfinder when choosing the most stable genes. UBQ1 and TUB were shown to be the most stable reference genes to use for normalizing RT-qPCR gene expression data during floral induction, whilst 25SrRNA1 and GAPDH were the least stable. Their use as a reference gene pair was validated by analyzing the expression of two differentially expressed target genes (PIL5 and LHP1). The UBQ1/TUB reference genes combination was able to reveal small significant differences in gene expression of the two target genes that were not detectable when using the least stable reference gene combination. These results can be used to inform the choice of reference genes to use in the study of the sugarcane floral induction pathway. Our work also demonstrates that both PIL5 and LHP1 are significantly up-regulated in the initial stages of photoperiodic induction of flowering in sugarcane.

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Optimizations for identifying reference genes in bone and cartilage bioengineering

BMC Biotechnology ◽

10.1186/s12896-021-00685-8 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Fei Xiong ◽

Xiangyun Cheng ◽

Chao Zhang ◽

Roland Manfred Klar ◽

Tao He

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Adipose Tissue ◽

Real Time ◽

Reference Gene ◽

Muscle Tissue ◽

Reference Genes ◽

Target Genes ◽

The Stability ◽

And Cartilage

Abstract Background Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) remains one of the best-established techniques to assess gene expression patterns. However, appropriate reference gene(s) selection remains a critical and challenging subject in which inappropriate reference gene selction can distort results leading to false interpretations. To date, mixed opinions still exist in how to choose the most optimal reference gene sets in accodrance to the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guideline. Therefore, the purpose of this study was to investigate which schemes were the most feasible for the identification of reference genes in a bone and cartilage bioengineering experimental setting. In this study, rat bone mesenchymal stem cells (rBMSCs), skeletal muscle tissue and adipose tissue were utilized, undergoing either chondrogenic or osteogenic induction, to investigate the optimal reference gene set identification scheme that would subsequently ensure stable and accurate interpretation of gene expression in bone and cartilage bioengineering. Results The stability and pairwise variance of eight candidate reference genes were analyzed using geNorm. The V0.15- vs. Vmin-based normalization scheme in rBMSCs had no significant effect on the eventual normalization of target genes. In terms of the muscle tissue, the results of the correlation of NF values between the V0.15 and Vmin schemes and the variance of target genes expression levels generated by these two schemes showed that different schemes do indeed have a significant effect on the eventual normalization of target genes. Three selection schemes were adopted in terms of the adipose tissue, including the three optimal reference genes (Opt3), V0.20 and Vmin schemes, and the analysis of NF values with eventual normalization of target genes showed that the different selection schemes also have a significant effect on the eventual normalization of target genes. Conclusions Based on these results, the proposed cut-off value of Vn/n + 1 under 0.15, according to the geNorm algorithm, should be considered with caution. For cell only experiments, at least rBMSCs, a Vn/n + 1 under 0.15 is sufficient in RT-qPCR studies. However, when using certain tissue types such as skeletal muscle and adipose tissue the minimum Vn/n + 1 should be used instead as this provides a far superior mode of generating accurate gene expression results. We thus recommended that when the stability and variation of a candidate reference genes in a specific study is unclear the minimum Vn/n + 1 should always be used as this ensures the best and most accurate gene expression value is achieved during RT-qPCR assays.

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