Selection of reference genes for quantitative real-time polymerase chain reaction in porcine embryos

To study gene expression and to determine distinctive characteristics of embryos produced by different methods, normalisation of the gene(s) of interest against reference gene(s) has commonly been employed. Therefore, the present study aimed to assess which reference genes tend to express more stably in single porcine blastocysts produced in vivo (IVO) or by parthenogenetic activation (PA), in vitro fertilisation (IVF) and somatic cell nuclear transfer (SCNT) using different analysis programs, namely geNorm, Normfinder and Bestkeeper. Commonly used reference genes including 18S rRNA (18S), H2A histone family, member Z (H2A), hypoxanthine phosphoribosyltransferase1 (HPRT1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ribosomal protein 4 (RPL4), peptidylprolyl isomerase A (PPIA), beta actin (ACTB), succinate dehydrogenase complex, subunit A (SDHA) and hydroxymethylbilane synthase (HMBS2) were analysed; most of them resulted in significantly (P < 0.05) different cycle threshold (CT) values in porcine embryos except for SDHA and H2A. In evaluation of stable reference genes across in vivo and in vitro porcine blastocysts, three kinds of programs showed slightly different results; however, there were similar patterns about the rankings of more or less stability overall. In conclusion, SDHA and H2A were determined as the most appropriate reference genes for reliable normalisation in order to find the comparative gene expression in porcine blastocysts produced by different methods, whereas 18S was regarded as a less-stable reference gene. The present study has evaluated the stability of commonly used reference genes for accurate normalisation in porcine embryos to obtain reliable results.

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

Genes ◽

10.3390/genes12070960 ◽

2021 ◽

Vol 12 (7) ◽

pp. 960

Author(s):

Meagan Archer ◽

Jianping Xu

Keyword(s):

Gene Expression ◽

Reference Gene ◽

Reference Genes ◽

Gene Selection ◽

Quantitative Polymerase Chain Reaction ◽

Specific Method ◽

Experimental Conditions ◽

Reference Gene Selection ◽

Physiological Processes ◽

The Stability

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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Identification of reference genes for RT-qPCR data normalisation in aging studies

Scientific Reports ◽

10.1038/s41598-019-50035-0 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Lourdes González-Bermúdez ◽

Teresa Anglada ◽

Anna Genescà ◽

Marta Martín ◽

Mariona Terradas

Keyword(s):

Gene Expression ◽

Reference Genes ◽

Quantitative Polymerase Chain Reaction ◽

Expression Levels ◽

Qpcr Data ◽

Age Related ◽

Specific Subset ◽

Aging Studies

Abstract Aging is associated with changes in gene expression levels that affect cellular functions and predispose to age-related diseases. The use of candidate genes whose expression remains stable during aging is required to correctly address the age-associated variations in expression levels. Reverse transcription quantitative-polymerase chain reaction (RT-qPCR) has become a powerful approach for sensitive gene expression analysis. Reliable RT-qPCR assays rely on the normalisation of the results to stable reference genes. Taken these data together, here we evaluated the expression stability of eight frequently used reference genes in three aging models: oncogene-induced senescence (OIS), in vitro and in vivo aging. Using NormFinder and geNorm algorithms, we identified that the most stable reference gene pairs were PUM1 and TBP in OIS, GUSB and PUM1 for in vitro aging and GUSB and OAZ1 for in vivo aging. To validate these candidates, we used them to normalise the expression data of CDKN1A, APOD and TFRC genes, whose expression is known to be affected during OIS, in vitro and in vivo aging. This study demonstrates that accurate normalisation of RT-qPCR data is crucial in aging research and provides a specific subset of stable reference genes for future aging studies.

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Comparison of gene expression in individual preimplantation bovine embryos produced by in vitro fertilisation or somatic cell nuclear transfer

Reproduction Fertility and Development ◽

10.1071/rd04128 ◽

2005 ◽

Vol 17 (5) ◽

pp. 487 ◽

Cited By ~ 24

Author(s):

Luiz Sergio de A. Camargo ◽

Anne M. Powell ◽

Vicente R. do Vale Filho ◽

Robert J. Wall

Keyword(s):

Gene Expression ◽

Somatic Cell Nuclear Transfer ◽

Nuclear Transfer ◽

Blastocyst Stage ◽

In Vitro Fertilisation ◽

Developmental Abnormalities ◽

Aberrant Gene Expression ◽

Aberrant Gene

In vitro fertilisation (IVF) and somatic cell nuclear transfer (SCNT) have been implicated in a variety of developmental abnormalities. Aberrant gene expression is likely to account for much of the diminished viability and developmental abnormalities observed. In the present study, the expression of multiple genes in IVF and SCNT bovine blastocyst-stage embryos were evaluated and compared with in vivo-produced embryos. Eleven genes expressed at and following maternal–zygotic transcription transition were evaluated in individual blastocysts by real-time polymerase chain reaction following RNA amplification. A subset of those genes was also evaluated in individual IVF and SCNT eight-cell embryos. A fibroblast-specific gene, expressed by nuclear donor cells, was also evaluated in IVF and SCNT embryos. The observed gene expression pattern at the eight-cell stage was not different between IVF and SCNT embryos (P > 0.05). In vitro fertilisation and SCNT blastocyst expression was lower (P < 0.01) for all genes compared with their in vivo-produced counterparts, except for lactate dehydrogenase isoenzyme A (P < 0.001). The patterns of gene expression of the IVF and SCNT blastocysts were indistinguishable. Neither SCNT eight-cell nor blastocyst-stage embryos expressed the gene used as a fibroblast marker (collagen VIα1). For the genes evaluated, the level of expression was influenced more by the environment than by the method used to produce the embryos. These results support the notion that if developmental differences observed in IVF- and SCNT-produced fetuses and neonates are the result of aberrant gene expression during the preimplantation stage, those differences in expression are subtle.

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Reference Gene Selection for Gene Expression Analyses in Mouse Models of Acute Lung Injury

International Journal of Molecular Sciences ◽

10.3390/ijms22157853 ◽

2021 ◽

Vol 22 (15) ◽

pp. 7853

Author(s):

Athanassios Fragoulis ◽

Kristina Biller ◽

Stephanie Fragoulis ◽

Dennis Lex ◽

Stefan Uhlig ◽

...

Keyword(s):

Gene Expression ◽

Acute Lung Injury ◽

Lung Injury ◽

Reference Gene ◽

Reference Genes ◽

Gene Selection ◽

Ex Vivo ◽

Qrt Pcr ◽

The Impact

qRT-PCR still remains the most widely used method for quantifying gene expression levels, although newer technologies such as next generation sequencing are becoming increasingly popular. A critical, yet often underappreciated, problem when analysing qRT-PCR data is the selection of suitable reference genes. This problem is compounded in situations where up to 25% of all genes may change (e.g., due to leukocyte invasion), as is typically the case in ARDS. Here, we examined 11 widely used reference genes for their suitability in commonly used models of acute lung injury (ALI): ventilator-induced lung injury (VILI), in vivo and ex vivo, lipopolysaccharide plus mechanical ventilation (MV), and hydrochloric acid plus MV. The stability of reference gene expression was determined using the NormFinder, BestKeeper, and geNorm algorithms. We then proceeded with the geNorm results because this is the only algorithm that provides the number of reference genes required to achieve normalisation. We chose interleukin-6 (Il‑6) and C-X-C motif ligand 1 (Cxcl-1) as the genes of interest to analyse and demonstrate the impact of inappropriate normalisation. Reference gene stability differed between the ALI models and even within the subgroup of VILI models, no common reference gene index (RGI) could be determined. NormFinder, BestKeeper, and geNorm produced slightly different, but comparable results. Inappropriate normalisation of Il-6 and Cxcl1 gene expression resulted in significant misinterpretation in all four ALI settings. In conclusion, choosing an inappropriate normalisation strategy can introduce different kinds of bias such as gain or loss as well as under- or overestimation of effects, affecting the interpretation of gene expression data.

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iRGvalid: A Robust in silico Method for Optimal Reference Gene Validation

Frontiers in Genetics ◽

10.3389/fgene.2021.716653 ◽

2021 ◽

Vol 12 ◽

Author(s):

Zhongxu Zhu ◽

Keqin Gregg ◽

Wenli Zhou

Keyword(s):

Gene Expression ◽

Reference Gene ◽

In Silico ◽

Reference Genes ◽

Target Gene ◽

Stable Reference Gene ◽

Expression Data ◽

Reference Gene Validation ◽

Cancer Types ◽

The Stability

BackgroundAppropriate reference genes are critical to accurately quantifying relative gene expression in research and clinical applications. Numerous efforts have been made to select the most stable reference gene(s), but a consensus has yet to be achieved. In this report, we propose an in silico reference gene validation method, iRGvalid, that can be used as a universal tool to validate the reference genes recommended from different resources so as to identify the best ones without a need for any wet lab validation tests.MethodsiRGvalid takes advantage of high throughput gene expression data and is built on a double-normalization strategy. First, the expression level of each individual gene is normalized against the total gene expression level of each sample, followed by a target gene normalization to the candidate reference gene(s). Linear regression analysis is then performed between the pre- and post- normalized target gene across the whole sample set to evaluate the stability of the reference gene(s), which is positively associated with the Pearson correlation coefficient, Rt. The higher the Rt value, the more stable the reference gene. We applied iRGvalid to 14 candidate reference genes to validate and identify the most stable reference genes in four cancer types: lung adenocarcinoma, breast cancer, colon adenocarcinoma, and nasopharyngeal cancer. The stability of the reference gene is evaluated both individually and in groups of all possible combinations.ResultsHighly stable reference genes resulted in high Rt values regardless of the target gene used. The highest stability was achieved with a specific combination of 3 to 6 reference genes. A few genes were among the best reference genes across the cancer types studied here.ConclusioniRGvalid provides an easy and robust method to validate and identify the most stable reference gene or genes from a pool of candidate reference genes. The inclusivity of large expression data sets as well as the direct comparison of candidate reference genes makes it possible to identify reference genes with universal quality. This method can be used in any other gene expression studies when large cohorts of expression data are available.

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Optimizations for Identifying Reference Genes in Bone and Cartilage Bioengineering

10.21203/rs.3.rs-96393/v1 ◽

2020 ◽

Author(s):

Fei Xiong ◽

Xiangyun Cheng ◽

Chao Zhang ◽

Roland Manfred Klar ◽

Tao He

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Adipose Tissue ◽

Reference Gene ◽

Muscle Tissue ◽

Reference Genes ◽

Target Genes ◽

Gene Set ◽

The Stability ◽

And Cartilage

Abstract Background：Quantitative reverse transcription polymerase chain reaction (qRT-PCR) is commonly considered as the best-established technique for gene expression assay. However, appropriate reference gene set selection remains the critical and challenging subject for the proper understanding of gene expression pattern. Mixed opinions pertain in how to choose optimal reference gene set according 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 was the most feasible for the identification of reference genes in bone and cartilage bioengineering experiments. 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 ensuring the 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 different schemes may 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 and eventual normalization of target genes showed that the different selection schemes have significant effect on the eventual normalization of target genes.Conclusions：Based on the results, the proposed cut-off value of Vn/n+1 under 0.15, according to geNorm algorithm, should be considered with caution, especially in certain tissue types such as skeletal muscle and adipose tissue. Instead, the minimum Vn/n+1 should be used as the cut-off for choosing the optimal reference gene set especially when the stability and variation of candidate reference genes in a specific study are unclear.

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Validation of reference genes for quantitative RT-PCR normalization inSuaeda aralocaspica, an annual halophyte with heteromorphism and C4 pathway without Kranz anatomy

PeerJ ◽

10.7717/peerj.1697 ◽

2016 ◽

Vol 4 ◽

pp. e1697 ◽

Cited By ~ 11

Author(s):

Jing Cao ◽

Lu Wang ◽

Haiyan Lan

Keyword(s):

Gene Expression ◽

Reference Gene ◽

Reference Genes ◽

Transcriptional Level ◽

28S Rrna ◽

Related Gene ◽

Kranz Anatomy ◽

Qrt Pcr ◽

C4 Pathway ◽

The Stability

Reverse transcription quantitative real-time polymerase chain reaction (qRT-PCR) is a powerful analytical technique for the measurement of gene expression, which depends on the stability of the reference gene used for data normalization.Suaeda aralocaspica, an annual halophyte with heteromorphic seeds and possessing C4 photosynthesis pathway without Kranz anatomy, is an ideal plant species to identify stress tolerance-related genes and compare relative expression at transcriptional level. So far, no molecular information is available for this species. In the present study, six traditionally used reference genes were selected and their expression stability in two types of seeds ofS. aralocaspicaunder different experimental conditions was evaluated. Three analytical programs, geNorm, NormFinder and BestKeeper, were used to assess and rank the stability of reference gene expression. Results revealed that although some reference genes may display different transcriptional profiles between the two types of seeds,β-TUB andGAPDHappeared to be the most suitable references under different developmental stages and tissues.GAPDHwas the appropriate reference gene under different germination time points and salt stress conditions, andACTINwas suitable for various abiotic stress treatments for the two types of seeds. For all the sample pools,β-TUB served as the most stable reference gene, whereas18S rRNAand28S rRNAperformed poorly and presented as the least stable genes in our study.UBQseemed to be unsuitable as internal control under different salt treatments. In addition, the expression of a photosynthesis-related gene (PPDK) of C4 pathway and a salt tolerance-related gene (SAT) ofS. aralocaspicawere used to validate the best performance reference genes. This is the first systematic comparison of reference gene selection for qRT-PCR work inS. aralocaspicaand these data will facilitate further studies on gene expression in this species and other euhalophytes.

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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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Reference gene screening of Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans for quantitative real-time PCR studies

Scientific Reports ◽

10.1038/s41598-019-54582-4 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Elin Verbrugghe ◽

Frank Pasmans ◽

An Martel

Keyword(s):

Real Time ◽

Reference Gene ◽

Reference Genes ◽

Batrachochytrium Dendrobatidis ◽

Expression Patterns ◽

Growth Stages ◽

Batrachochytrium Salamandrivorans ◽

The Stability ◽

Different Growth Stages

AbstractReal-time quantitative PCR studies largely depend on reference genes for the normalization of gene expression. Stable reference genes should be accurately selected in order to obtain reliable results. We here present a study screening commonly used reference genes (TEF1F, α-centractin, Ctsyn1, GAPDH, R6046, APRT and TUB) in the chytrid fungi Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal), which cause the lethal amphibian skin disease chytridiomycosis. We evaluated the stability of the reference gene candidates during different growth stages of the fungi, using different statistical software packages: ΔCT, BestKeeper, GeNorm, NormFinder and RefFinder. In order to reflect the in vivo situation, the stability of the candidates was assessed when taking all growth stages into account. Using an ex-vivo approach, we tested whether the expression of GAPDH, TUB, R6046 and APRT (Bd) and GAPDH, TUB, R6046 and α-centractin (Bsal) remained stable when these fungi came in contact with host tissue. Finally, their role as in vivo reference genes was examined in skin tissue of experimentally infected midwife toads (Alytes obstetricans) (Bd) and fire salamanders (Salamandra salamandra) (Bsal). Summarized, the present study provides guidance for selecting appropriate reference genes when analyzing expression patterns of these fungal organisms during different growth stages and in Bd- or Bsal-infected tissues.

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