High-throughput SNP genotyping by single-tube PCR with Tm-shift primers

An RNase H-Like gene complements resistance to Bean common mosaic necrosis virus in Phaseolus vulgaris

Bean common mosaic virus and Bean common mosaic necrosis virus (BCMNV) are related positive-sense RNA potyviruses that limit the production of common bean (Phaseolus vulgaris L.) worldwide. Potyviruses infect other legume species, such as Glycine max, which can serve as a source of orthologous resistance genes. The bc-1 on chromosome Pv03 in P. vulgaris and Rsv4 on Gm02 in G. max are syntenic gene regions that confer resistance to Potyviruses. Receptor-like kinases underlie both gene regions, and a linked RNase H-Like protein, which enhances potyvirus resistance, was recently associated with Rsv4. We sought to determine if RNase H-Like encoding genes are similarly located in the bc-1 region and enhance resistance to BCMNV. Synteny analysis between P. vulgaris and G. max revealed RNase H-Like genes near the bc-1 locus. Positional cloning among reference genomes and select genotypes, along with linkage mapping in recombinant inbred line and F2 populations, identified the RNase H-Like 1 gene, which enhanced resistance to BCMNV NL-3 strain when combined with I, bc-1, and bc-u or with bc-1 and bc-u genes by reducing systemic spread of susceptible symptoms in non-inoculated leaves. A single nucleotide polymorphism marker, G03_4166082, was developed to track the resistant and susceptible alleles for RNase H-Like 1 in breeding programs. Overall, this study advances the understanding of the complex mechanisms underlying BCMNV resistance in common bean.

Single-tube Ptprc SNP genotyping of JAXBoy (CD45.1) and C57BL/6J (CD45.2) mice by endpoint PCR and gel electrophoresis

Allelic variation at the Ptprc gene, which encodes the pan-leukocyte marker CD45/Ly5, is commonly exploited to track hematopoietic reconstitution by flow cytometry in mixed bone marrow chimera transplant experiments. Historically, this was accomplished using bone marrow from C57BL/6 (Ptprcb/CD45.2/Ly5.2) and congenic B6.SJL-PtprcaPepcb/Boy (Ptprca/CD45.1/Ly5.1) mice. Recently, the Jackson Laboratory directly CRISPR-engineered the Ptprca allele in C57BL/6J mice. This new isogenic strain, termed JAXBoy, differs from wild-type C57BL/6J mice by two nucleotides, compared to the biologically significant 37 megabase (Mb) SJL interval retained in B6.SJL-PtprcaPepcb/Boy/J mice. Currently, Ptprc/CD45 variants are identified by flow cytometry or allele-specific real-time PCR, both of which require specialized workflows and equipment compared to standard genotyping of endpoint PCR products by gel electrophoresis. Here, we employed allele-specific oligonucleotides in conjunction with differential incorporation of a long non-specific oligo 5'-tail to allow for simultaneous identification of the Ptprca and Ptprcb alleles using endpoint PCR and gel electrophoresis. This method allows for integration of Ptprc genotyping into standard genotyping workflows, which use a single set of thermocycling and gel electrophoresis conditions. Importantly, the strategy of primer placement and tail addition described here can be adapted to discriminate similar single- or multi-nucleotide polymorphisms at other genomic loci.

A robust SNP-haplotype assay for Bct gene region conferring resistance to beet curly top virus in common bean (Phaseolus vulgaris L.)

Beet curly top virus (BCTV), which is synonymous with curly top virus (CTV), causes significant yield loss in common bean (snap and dry beans) cultivars and several other important crops. Common bean cultivars have been found to be resistant to CTV, but screening for resistance is challenging due to the cyclical nature of epidemics and spotty feeding by the leafhopper that vectors the virus. We used an SNP dataset for the Snap Bean Association Panel (SnAP) agro-inoculated with CTV-Logan (CA/Logan) strain to locate the Bct gene region to a 1.7-Mb interval on chromosome Pv07 using genome-wide association study (GWAS) analysis. Recombinant lines from the SnAP were used to further narrow the Bct region to a 58.0-kb interval. A missense SNP (S07_2970381) in candidate gene Phvul.007G036300 Exonuclease V (EXO5) was identified as the most likely causal mutation, and it was the most significant SNP detected by GWAS in a dry bean population (DBP) naturally infected by the CTV-Worland (Wor) strain. Tm-shift assay markers developed for SNP S07_2970381 and two linked SNPs, S07_2970276 and S07_2966197, were useful for tracking different origins of the Bct EXO5 candidate gene resistance to CTV in common bean. The three SNPs identified four haplotypes, with haplotype 3-1 (Haplo3-1) of Middle American origin associated with the highest levels of CTV resistance. This SNP-haplotype assay will enable breeders to track resistance sources and to develop cultivars with better CTV resistance.

RT-qPCR genotyping assays for differentiating Rift Valley fever phlebovirus strains

Rift Valley fever phlebovirus (RVFV) is an emerging, mosquito-borne, zoonotic pathogen. Real time RT-qPCR genotyping (GT) assays were developed to differentiate between two RVFV wild-type strains (128B-15 and SA01-1322) and a vaccine strain (MP-12). The GT assay uses a one-step RT-qPCR mix, with two different RVFV strain-specific primers (either forward or reverse) with long or short G/C tags and a common primer (either forward or reverse) for each of the 3 genomic segments. The GT assay produces PCR amplicons with unique melting temperatures that are resolved in a post PCR melt curve analysis for strain identification. Furthermore, a strain specific RT-qPCR (SS-PCR) assay was developed to allow for specific detection of low titer RVFV strains in mixed RVFV samples. Our data shows that the GT assays are capable of differentiating L, M, and S segments of RVFV strains 128B-15 versus MP-12, and 128B-15 versus SA01-1322. The SS-PCR assay results revealed that it can specifically amplify and detect a low titer MP-12 strain in mixed RVFV samples. Overall, these two novel assays are useful as screening tools for determining reassortment of the segmented RVFV genome during co-infections, and could be adapted and applied for other segmented pathogens of interest.

Detection of Five Types of HPV Genotypes Causing Anogenital Warts (Condyloma Acuminatum) Using PCR-Tm Analysis Technology

Objectives

Condyloma acuminatum (CA) is a common sexually transmitted disease caused by human papillomavirus (HPV) infection. We established a high-throughput, simple, low-cost, and accurate HPV-typing assay (polymerase chain reaction-melting temperature [PCR-Tm] analysis) to detect HPV in CA.

Materials and Methods

We detected 280 cervical scraping samples, including positive samples of HPV-6 (26), HPV-11 (12), HPV-16 (22), HPV-42 (18), HPV-43 (25), HPV-multiple (19), HPV- other type (58), and HPV-negative samples (100). All samples were compared by PCR-Tm analysis and a flow fluorescence hybridization assay. Sequencing was used to confirm the results of the PCR-Tm analysis.

Results

PCR-Tm analysis was specific for each genotype (HPV-6, HPV-11, HPV-16, HPV-42, and HPV-43). The sensitivity of the PCR-Tm analysis assay for each genotype was 10³, 10³, 10³, 10³, and 10² copies/reaction, respectively. Most of the 158 samples, including 58 HPV-other type positive and 100 HPV-negative samples tested by the flow fluorescence hybridization assay, were tested negative by PCR-Tm analysis. For the 122 remaining samples, 26 HPV-6, 12 HPV-11, 22 HPV-16, 18 HPV-42, 25 HPV-43, and 19 multiple HPV infections were detected through PCR-Tm analysis. In total, 25 HPV-6, 12 HPV-11, 21 HPV-16, 18 HPV-42, 25 HPV-43, and only 10 multiple HPV infections were detected by the flow fluorescence hybridization assay. The kappa coefficient for the analysis of PCR-Tm analysis and flow fluorescence hybridization assay was 0.940 (P < 0.0001), and the 95% confidence interval of the kappa coefficient was 90.3–97.7%.

Conclusion

PCR-Tm analysis enabled the detection of HPV-6, HPV-11, HPV-16, HPV-42, and HPV-43, including single and multiple infections.

Coding Mutations in Vacuolar Protein-Sorting 4 AAA+ ATPase Endosomal Sorting Complexes Required for Transport Protein Homologs Underlie bc-2 and New bc-4 Gene Conferring Resistance to Bean Common Mosaic Virus in Common Bean

Bean common mosaic virus (BCMV) is a major disease in common bean (Phaseolus vulgaris L.). Host plant resistance is the most effective strategy to minimize crop damage against BCMV and the related Bean common mosaic necrosis virus (BCMNV). To facilitate breeding for resistance, we sought to identify candidate genes and develop markers for the bc-2 gene and the unknown gene with which it interacts. Genome-wide association study (GWAS) of the Durango Diversity Panel (DDP) identified a peak region for bc-2 on chromosome Pv11. Haplotype mapping narrowed the bc-2 genomic interval and identified Phvul.011G092700, a vacuolar protein-sorting 4 (Vps4) AAA+ ATPase endosomal sorting complexes required for transport (ESCRT) protein, as the bc-2 candidate gene. The race Durango Phvul.011G092700 gene model, bc-2 ^{[UI 111]}, contains a 10-kb deletion, while the race Mesoamerican bc-2 ^[Robust] consists of a single nucleotide polymorphism (SNP) deletion. Each mutation introduces a premature stop codon, and they exhibit the same interaction with the pathogroups (PGs) tested. Phvul.005G125100, another Vps4 AAA+ ATPase ESCRT protein, was identified as the candidate gene for the new recessive bc-4 gene, and the recessive allele is likely an amino acid substitution in the microtubule interacting and transport (MIT) domain. The two Vps4 AAA+ ATPase ESCRT proteins exhibit high similarity to the Zym Cucsa.385040 candidate gene associated with recessive resistance to Zucchini yellow mosaic virus in cucumber. bc-2 alone has no resistance effect but, when combined with bc-4, provides resistance to BCMV (except PG-V) but not BCMNV, and, when combined with bc-u ^d, provides resistance to BCMV (except BCMV PG-VII) and BCMNV. So instead of different resistance alleles (i.e., bc-2 and bc-2 ²), there is only bc-2 with a differential reaction based on whether it is combined with bc-4 or bc-u ^d , which are tightly linked in repulsion. The new tools and enhanced understanding of this host-virus pathogen interaction will facilitate breeding common beans for resistance to BCMV and BCMNV.

Geographic distribution of the E1 family of genes and their effects on reproductive timing in soybean

BACKGROUND

Soybean is an economically important crop which flowers predominantly in response to photoperiod. Several major loci controlling the quantitative trait for reproductive timing have been identified, of which allelic combinations at three of these loci, E1, E2, and E3, are the dominant factors driving time to flower and reproductive period. However, functional genomics studies have identified additional loci which affect reproductive timing, many of which are less understood. A better characterization of these genes will enable fine-tuning of adaptation to various production environments. Two such genes, E1La and E1Lb, have been implicated in flowering by previous studies, but their effects have yet to be assessed under natural photoperiod regimes.

RESULTS

Natural and induced variants of E1La and E1Lb were identified and introgressed into lines harboring either E1 or its early flowering variant, e1-as. Lines were evaluated for days to flower and maturity in a Maturity Group (MG) III production environment. These results revealed that variation in E1La and E1Lb promoted earlier flowering and maturity, with stronger effects in e1-as background than in an E1 background. The geographic distribution of E1La alleles among wild and cultivated soybean revealed that natural variation in E1La likely contributed to northern expansion of wild soybean, while breeding programs in North America exploited e1-as to develop cultivars adapted to northern latitudes.

CONCLUSION

This research identified novel alleles of the E1 paralogues, E1La and E1Lb, which promote flowering and maturity under natural photoperiods. These loci represent sources of genetic variation which have been under-utilized in North American breeding programs to control reproductive timing, and which can be valuable additions to a breeder's molecular toolbox.

NAC Candidate Gene Marker for bgm-1 and Interaction With QTL for Resistance to Bean Golden Yellow Mosaic Virus in Common Bean

Genetic resistance is the primary means for control of Bean golden yellow mosaic virus (BGYMV) in common bean (Phaseolus vulgaris L.). Breeding for resistance is difficult because of sporadic and uneven infection across field nurseries. We sought to facilitate breeding for BGYMV resistance by improving marker-assisted selection (MAS) for the recessive bgm-1 gene and identifying and developing MAS for quantitative trait loci (QTL) conditioning resistance. Genetic linkage mapping in two recombinant inbred line populations and genome-wide association study (GWAS) in a large breeding population and two diversity panels revealed a candidate gene for bgm-1 and three QTL BGY4.1, BGY7.1, and BGY8.1 on independent chromosomes. A mutation (5 bp deletion) in a NAC (No Apical Meristem) domain transcriptional regulator superfamily protein gene Phvul.003G027100 on chromosome Pv03 corresponded with the recessive bgm-1 resistance allele. The five bp deletion in exon 2 starting at 20 bp (Pv03: 2,601,582) is expected to cause a stop codon at codon 23 (Pv03: 2,601,625), disrupting further translation of the gene. A T m -shift assay marker named PvNAC1 was developed to track bgm-1. PvNAC1 corresponded with bgm-1 across ∼1,000 lines which trace bgm-1 back to a single landrace "Garrapato" from Mexico. BGY8.1 has no effect on its own but exhibited a major effect when combined with bgm-1. BGY4.1 and BGY7.1 acted additively, and they enhanced the level of resistance when combined with bgm-1. T m -shift assay markers were generated for MAS of the QTL, but their effectiveness requires further validation.

A novel A > G polymorphism in the intron 2 of TBX3 gene is significantly associated with body size in donkeys

T-box transcription factor 3 (TBX3) gene encodes a transcriptional suppressor and plays an important role in embryonic development, which belongs to the T-box family. TBX3 also has been found to be associated with body size traits in horse that is a relative of donkey. Therefore, TBX3 is considered as a promising candidate gene for economic traits of donkey. This study aimed to reveal the significant variation of TBX3 gene in Dezhou donkey and explores the relationship between genotypes and body sizes. In this study, an A > G mutation was found in the intron 2 of TBX3 gene by sequencing, and three genotypes (AA, GG and AG) were identified in 380 Dezhou donkey individuals with Tm-shift method. Association analysis illustrated that there were significant differences between AA and GG genotype in body length, body height, chest depth, chest circumference, body weight, hucklebone width and rump length. Our results demonstrated that the polymorphism of TBX3 is significantly associated with body size traits, which can serve as a marker to improve donkey production performance.

Genotyping of RHD c.1227G>A allele by melting curve analysis

BACKGROUND

DEL is the weakest known D-positive phenotype and is detectable only by adsorption and elution tests. RHD c.1227G>A is an important marker for DEL phenotype in East Asians. The aim of this study was to develop a method for RHD c.1227G>A genotyping by single-tube PCR with melting curve analysis.

METHODS

Two GC-rich tails of different lengths were attached to the 5'-end of allele-specific primers for RHD 1227G and 1227A alleles, such that RHD c.1227G>A could be distinguished by the melting temperature. A total of 145 D-negative Chinese Han blood donors were genotyped for RHD c.1227G>A by melting curve analysis, conventional polymerase chain reaction with sequence-specific primers (PCR-SSP), and sequencing.

RESULTS

In 143 subjects (143/145, 98.6%), PCR-SSP and melting curve analysis produced consistent results with RHD exon 9 sequencings. Two samples were genotyped as RHD 1227G/A by PCR-SSP, but as RHD 1227A/A or A/- by melting curve analysis. These two samples were confirmed to be RHD 1227A/A or A/-. Based on RHD exon 9 sequencing, the accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of the melting curve analysis for detecting both RHD 1227A and 1227G were all 100%. In contrast, the accuracy, specificity and positive predictive value of PCR-SSP for RHD 1227G detection were 98.62%, 98.21% and 94.29%, respectively, which were lower than those observed with the melting curve analysis.

CONCLUSION

Melting curve analysis for RHD c.1227G>A genotyping is a simple, rapid, and reliable method, superior to conventional PCR-SSP.

Identification of Echinococcus granulosus Genotypes G1 and G3 by SNPs Genotyping Assays

Echinococcus granulosus sensu lato (s.l.) is the causative agent of cystic echinococcosis in animals and humans. Different E. granulosuss.l. genotypes exhibit great diversity in their life cycle, host selectivity and pathogenicity. For this reason, the study of genetic variation within Echinococcus species is of importance for their epidemiological implication. We employed two SNP genotyping technologies to distinguish G1 and G3 E. granulosus sensu stricto (s.s.). genotypes. The genotypes of DNA samples (n = 28) extracted from hydatid cysts of different animal species were identified by amplification and sequencing of a fragment of the mitochondrial nad5 gene. Two SYBR green and three TaqMan real time PCR assays were developed for targeting of three nad5 informative positions (SNP758, 1123, and 1380) known to be able to discriminate G1 from G3. Genotyping by SYBR Green PCR based on cycle threshold (Ct) with melting temperature (Tm) analysis and performed on SNP1123 and SNP1380 failed to identify one DNA sample. TaqMan assays for SNP758, 1123 and 1380 effectively confirmed genotype identification obtained by Sanger sequencing. Our results demonstrated that the combination of the three Taqman assays developed in this study represents a valuable and cost effective tool alternative to DNA sequencing for E. granulosus s.s. genotyping.

Design and characterization of a SYBR Green I-based melting curve method for investigation of HER2I655V polymorphism in breast cancer

Background

Breast cancer is a disease in which cell grows rapidly forming a mass in the breast. HER2 polymorphisms Ile655Val have been studied as biomarkers for breast cancer and may comprise a risk factor of cardiac toxicity for breast cancer-consuming trastuzumab. Aim of work: In this study, we developed a simple, low cost, and rapid test to detect polymorphism at HER2 gene using SYBR Green I-based melting curve method.

Subjects and methods

In this report, we performed allelic discrimination with real-time temperature melting (Tm) Shift SYBR Green I-based melting curve method. The melting profiles of amplified DNA HER-2 Ile655Val and its characteristics were analyzed.

Result

Tm value of HER2 GG and AA alleles were 85 ± 0.14 °C and 82.5 ± 0.23 °C, respectively, while cycle threshold (Ct) value of GG, AG, and AA alleles were 19.6 ± 0.27, 22.5 ± 0.23, 18.6 ± 0.22 correspondingly; furthermore, no template control has shown consisting Ct value at 31.18 ± 0.27. The developed methods’ characteristics were optimum annealing at 62 °C and Kappa coefficient value 1 with the mean almost consistent with PCR-sequencing. The coefficient of variability for intra-assay of GG, AG, and AA was in the range of 0.2–1%, while the coefficient of variability for inter-assay for each were in the range 0.7–1%. Further, based on PCR, shelf-life assay has shown stability for 3 months of storage observation.

Conclusion

This approach may be considered as simple, rapid, and low cost supporting the rapid study of HER2 epidemiology. Furthermore, the developed methods potentially facilitate clinicians in dealing with breast cancer patients, especially in considering about the cardiotoxicity effect of trastuzumab.

Genome-Wide Association Mapping of bc-1 and bc-u Reveals Candidate Genes and New Adjustments to the Host-Pathogen Interaction for Resistance to Bean Common Mosaic Necrosis Virus in Common Bean

Bean common mosaic necrosis virus (BCMNV) is a major disease in common bean (Phaseolus vulgaris L.). Host plant resistance is the primary disease control. We sought to identify candidate genes to better understand the host-pathogen interaction and develop tools for marker-assisted selection (MAS). A genome-wide association study (GWAS) approach using 182 lines from a race Durango Diversity Panel (DDP) challenged by BCMNV isolates NL-8 [Pathogroup (PG)-III] and NL-3 (PG-VI), and genotyped with 1.26 million single-nucleotide polymorphisms (SNPs), revealed significant peak regions on chromosomes Pv03 and Pv05, which correspond to bc-1 and bc-u resistance gene loci, respectively. Three candidate genes were identified for NL-3 and NL-8 resistance. Side-by-side receptor-like protein kinases (RLKs), Phvul.003G038700 and Phvul.003G038800 were candidate genes for bc-1. These RLKs were orthologous to linked RLKs associated with virus resistance in soybean (Glycine max). A basic Leucine Zipper (bZIP) transcription factor protein is the candidate gene for bc-u. bZIP protein gene Phvul.005G124100 carries a unique non-synonymous mutation at codon 14 in the first exon (Pv05: 36,114,516 bases), resulting in a premature termination codon that causes a nonfunctional protein. SNP markers for bc-1 and bc-u and new markers for I and bc-3 genes were used to genotype the resistance genes underpinning BCMNV phenotypes in the DDP, host group (HG) differentials, and segregating F₃ families. Results revealed major adjustments to the current host-pathogen interaction model: (i) there is only one resistance allele bc-1 for the Bc-1 locus, and differential expression of the allele is based on presence vs. absence of bc-u; (ii) bc-1 exhibits dominance and incomplete dominance; (iii) bc-1 alone confers resistance to NL-8; (iv) bc-u was absent from HGs 2, 4, 5, and 7 necessitating a new gene symbol bc-u ^d to reflect this change; (v) bc-u ^d alone delays susceptible symptoms, and when combined with bc-1 enhanced resistance to NL-3; and (vi) bc-u ^d is on Pv05, not Pv03 as previously thought. These candidate genes, markers, and adjustments to the host-pathogen interaction will facilitate breeding for resistance to BCMNV and related Bean common mosaic virus (BCMV) in common bean.

NF-κB2 and RELB offer prognostic information in colorectal cancer and NFKB2 rs7897947 represents a genetic risk factor for disease development

The Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) family of transcription factors plays an important role in immune responses and cancer development and progression. We have focused on NF-κB2 and RELB of the alternative pathway of NF-κB, which remains largely underexplored in colorectal cancer (CRC). We found that NF-κB2 and RELB protein levels were upregulated in tumour and surrounding stromal tissue compared to distant non-neoplastic tissue (NN) and associated stroma (p<0.001 in all associations). Moreover, low RELB protein expression was associated with decreased overall survival (p = 0.032). Lower RELB gene expression levels were observed in tumour compared to NN tissue (p = 0.003) and were associated with shorter time to progression (TTP) (p = 0.025). NF-κB2 gene expression levels were similar in tumour and NN tissue, but higher tumour levels were prognostic for improved survival (p = 0.038) and TTP (p<0.001). We also assessed the significance of two NF-κB2 genetic polymorphisms, rs12769316 and rs7897947. Both polymorphisms were associated with lymph node infiltration (p = 0.045 and p = 0.009, respectively). In addition, rs12769316 AA homozygotes relapsed less often compared to G allele carriers (p = 0.029). Moreover, rs7897947 allele frequencies differed significantly between CRC patients and healthy controls (p<0.001) and the minor allele (G) was associated with reduced risk for developing CRC (p<0.001, OR: 0.527, 95% CI: 0.387-0.717). In conclusion, the alternative NF-κB pathway appears deregulated in CRC. Moreover, NF-κB2 and RELB expression levels seem to be significant for the clinical outcome of CRC patients and rs7897947 appears to be a risk factor for CRC development.

Comparison Between Three Molecular Diagnostics for the Identification of Heterozygous Hemoglobin E

BACKGROUND AND OBJECTIVES

Hemoglobin E is a variant hemoglobin caused due to the base substitution G→A at codon 26 in the β-globin-coding gene that is followed by the alteration of glutamic acid (GAG) to lysine (AAG). Various types of molecular analysis methods such as tetra-primer amplification refractory mutation system (T-ARMS-PCR), Tm-shift real-time polymerase chain reaction (Tm-shift qPCR) and high-resolution melting analysis (HRMA) are commonly used to detect several mutations in the β-globin-coding gene. This study was conducted to compare the detection result of Cd 26 (G→A) mutation in the β-globin-coding gene of heterozygous HbE between the above-mentioned methods.

MATERIALS AND METHODS

DNA samples were isolated from blood archive of heterozygous HbE and analyzed for the detection of the mutation using HRMA and Tm-shift on a real-time PCR instrument, whereas T-ARMS analysis was performed on a conventional PCR equipment. High resolution melt v3.1 software and Bio-Rad CFX Manager software were used to analyze the result of HRMA and Tm-shift qPCR, whereas the T-ARMS-PCR result was analyzed by observing the number and size of DNA bands on gel electrophoresis.

RESULTS

Among 21 samples, the Cd 26 mutation was detected in numbers 18, 19 and 21 by HRMA, Tm-shift qPCR and T-ARMS-PCR. DNA Sequencing confirmed Cd 26 mutation on 5 ambiguous samples and revealed two homozygous mutation.

CONCLUSION

The Cd 26 (G→A) mutation was detected in proportions 100, 91 and 86% by T-ARMS-PCR, Tm-shift qPCR and HRMA, respectively.

Single nucleotide polymorphisms in transcription factor genes associated with susceptibility to oral cancer

Oral cancer is a major public health concern in the Asian countries predominated by India which accounts for 33.81% of the annual global oral cancer burden. The well-established high-risk factors associated with oral cancer include tobacco, areca nut, alcohol consumption, and high-risk human papilloma virus types 16/18. Additionally, in the past two decades, the critical role of the genomic constitution of individuals in oral cancer susceptibility has emerged. Accumulating evidence indicates the association of several single nucleotide polymorphisms (SNPs) with oral cancer risk. Thus in the current study, we assessed the association of thirteen SNPs in seven transcription factor genes along with HBB (a control SNP) to identify high-risk genotypes associated with increased oral cancer risk in an Indian cohort of tobacco habitués. Fourteen SNPs were investigated in 500 patients with oral cancer and 500 clinically healthy long-term tobacco users as controls of Indian ethnicity. Allelic discrimination real-time polymerase chain reaction was the method of choice for genotyping the samples. Logistic regression analysis was performed and the association of SNPs with oral cancer risk was estimated using odds ratio (OR) and 95% confidence interval (CI). We observed five SNPs-rs2051526 (ETV6), rs6021247 (NFATC2), rs3757769 (SND1), rs7085532 (TCF7L2), and rs7778413 (SND1) indicating increased oral cancer risk with OR ranging from 1.61 to 34.60. Further, as a proof of concept, the coinheritance of high-risk genotypes in rs6021247 (NFATC2) GG (OR, 2.77; CI, 2.09-3.69) and rs7778413 (SND1) CC (OR, 34.60; CI, 17.32-69.13) reflected further increase in the risk with OR-49.94 (CI, 16.25-153.48). The present study indicates the association of transcription factor SNPs with increased oral cancer risk constituting "predictive biomarkers" in oral cancers.

Fine-mapping of angular leaf spot resistance gene Phg-2 in common bean and development of molecular breeding tools

KEY MESSAGE

The Common Bean Angular Leaf Spot Resistance Gene Phg-2 was fine-mapped to a 409-Kbp region, and molecular markers for breeders were developed and validated in field experiments. Common bean (Phaseolus vulgaris L.) is an important food legume in Latin America, Asia and Africa. It is an important source of protein, carbohydrates and micro-minerals, particularly for smallholder farmers. Common bean productivity is affected by angular leaf spot (ALS) disease caused by the pathogenic fungus Pseudocercospora griseola, resulting in significant yield losses, particularly in low-input smallholder farming systems in the tropics. The ALS resistance gene Phg-2, which was found in several highly resistant common bean genotypes, was investigated in crosses between Mesoamerican pre-breeding lines and elite Andean breeding lines. Next-generation sequencing (NGS) data sets were used to design new SNP-based molecular markers. The Phg-2 locus was confirmed to be the major locus providing ALS resistance in these crosses. The locus was fine-mapped to a 409-Kbp region on chromosome 8. Two clusters of highly related LRR genes were identified in this region, which are the best candidate genes for Phg-2. Molecular markers were identified that are closely linked to the Phg-2 resistance gene and also highly specific to the donor germplasm. Marker-assisted selection (MAS) was used to introgress the Phg-2 resistance locus into Andean breeding germplasm using MAB lines. The usefulness of molecular markers in MAS was confirmed in several field evaluations in complex breeding crosses, under inoculation with different ALS pathotypes. This project demonstrates that NGS data are a powerful tool for the characterization of genetic loci and can be applied in the development of breeding tools.

Establishment of a Tm-shift Method for Detection of Cat-Derived Hookworms

Melting temperature shift (T_m-shift) is a new detection method that analyze the melting curve on real-time PCR thermocycler using SYBR Green I fluorescent dye. To establish a T_m-shift method for the detection of Ancylostoma ceylanicum and A. tubaeforme in cats, specific primers, with GC tail of unequal length attached to their 5′ end, were designed based on 2 SNP loci (ITS101 and ITS296) of the internal transcribed spacer 1 (ITS1) sequences. The standard curve of T_m-shift was established using the standard plasmids of A. ceylanicum (AceP) and A. tubaeforme (AtuP). The T_m-shift method stability, sensitivity, and accuracy were tested with reference to the standard curve, and clinical fecal samples were also examined. The results demonstrated that the 2 sets of primers based on the 2 SNPs could accurately distinguish between A. ceylanicum and A. tubaeforme. The coefficient of variation (CV) of T_m-values of AceP and AtuP was 0.07% and 0.06% in ITS101 and was 0.06% and 0.08% in ITS296, respectively. The minimum detectable DNA concentration was 5.22×10⁻⁶ and 5.28×10⁻⁶ ng/μl samples of AceP and AtuP, respectively. The accuracy of T_m-shift method reached 100% based on examination of 10 hookworm DNA samples with known species. In the clinical detection of hookworm in 69 stray cat fecal sample, the T_m-shift detection results were consistent with the microscopic examination and successfully differentiated between the 2-hookworm species. In conclusion, the developed method is a rapid, sensitive and accurate technique and can provide a promising tool for clinical detection and epidemiological investigation of cat-derived hookworms.

Allele-Specific Isothermal Amplification Method Using Unmodified Self-Stabilizing Competitive Primers

Rapid and specific detection of single nucleotide polymorphisms (SNPs) related to drug resistance in infectious diseases is crucial for accurate prognostics, therapeutics and disease management at point-of-care. Here, we present a novel amplification method and provide universal guidelines for the detection of SNPs at isothermal conditions. This method, called USS-sbLAMP, consists of SNP-based loop-mediated isothermal amplification (sbLAMP) primers and unmodified self-stabilizing (USS) competitive primers that robustly delay or prevent unspecific amplification. Both sets of primers are incorporated into the same reaction mixture, but always targeting different alleles; one set specific to the wild type allele and the other to the mutant allele. The mechanism of action relies on thermodynamically favored hybridization of totally complementary primers, enabling allele-specific amplification. We successfully validate our method by detecting SNPs, C580Y and Y493H, in the Plasmodium falciparum kelch 13 gene that are responsible for resistance to artemisinin-based combination therapies currently used globally in the treatment of malaria. USS-sbLAMP primers can efficiently discriminate between SNPs with high sensitivity (limit of detection of 5 × 101 copies per reaction), efficiency, specificity and rapidness (<35 min) with the capability of quantitative measurements for point-of-care diagnosis, treatment guidance, and epidemiological reporting of drug-resistance.

Selection criteria for SNP loci to maximize robustness of high-resolution melting analysis for plant breeding

DNA markers are useful for identifying genes and developing new genetic materials for breeding and genetic research. High-resolution melting (HRM) analysis can detect a single nucleotide polymorphism (SNP) in two polymerase chain reaction (PCR) fragments as a melting temperature (Tm) difference without additional experimental steps, such as gel electrophoresis. To design a method for developing reliable HRM markers that discriminate between homozygous alleles containing SNPs, we tested new evaluation indexes related to the thermodynamics of double-stranded DNA to find one that maximizes the difference in Tm values between PCR fragments. We found that differences in the change in Gibbs free energy (ΔG°) correlated with actual differences in Tm values. Optimization of the nearest neighboring nucleotide (NNN) of a SNP by nucleotide substitution in the primer and reducing the size of the PCR fragment both enlarged the actual differences in Tm. The genetic DNA markers we developed by NNN substitution, termed NNNs-HRM markers, could be precisely mapped within soybean chromosomes by linkage analysis. We developed a Perl script pipeline to enable the automatic design of a massive number of NNNs-HRM markers; these scripts are freely available and would be useful for practical breeding programs for other plant species.

Resequencing of Common Bean Identifies Regions of Inter-Gene Pool Introgression and Provides Comprehensive Resources for Molecular Breeding

Common bean ( L.) is the most important grain legume for human consumption and is a major nutrition source in the tropics. Because bean production is reduced by both abiotic and biotic constraints, current breeding efforts are focused on the development of improved varieties with tolerance to these stresses. We characterized materials from different breeding programs spanning three continents to understand their sequence diversity and advance the development of molecular breeding tools. For this, 37 varieties belonging to , (A. Gray), and L. were sequenced by whole-genome sequencing, identifying more than 40 million genomic variants. Evaluation of nuclear DNA content and analysis of copy number variation revealed important differences in genomic content not only between and the two other domesticated species, but also within , affecting hundreds of protein-coding genomic regions. A large number of inter-gene pool introgressions were identified. Furthermore, interspecific introgressions for disease resistance in breeding lines were mapped. Evaluation of newly developed single nucleotide polymorphism markers within previously discovered quantitative trait loci for common bacterial blight and angular leaf spot provides improved specificity to tag sources of resistance to these diseases. We expect that this dataset will provide a deeper molecular understanding of breeding germplasm and deliver molecular tools for germplasm development, aiming to increase the efficiency of bean breeding programs.

Insecticide susceptibility status of invasive Aedes albopictus across dengue endemic districts of Odisha, India

BACKGROUND

Aedes albopictus is currently the most invasive mosquito species in the world. Keeping in view the wide emergence of insecticide resistance, it is imperative to focus on the current susceptibility status for various insecticides in Ae. albopictus. This study focused on understanding the insecticide resistance mechanism of Ae. albopictus collected from dengue-endemic districts of Odisha.

RESULTS

Insecticide resistance was evaluated by using standardized bioassay kits (WHO) and biochemical analysis. Larval bioassays revealed the highest level of resistance from Jaipur (JP) population with a RR₅₀ of 15.3 and LC₅₀ of 1.177 ppm compared with an LC₅₀ of 0.077 for the susceptible strain LabS. Results indicated the presence of dichlorodiphenyltrichloroethane resistance in the majority of adult populations. Elevated activity of nonspecific esterases and cytochrome P450s MFO indicated probable resistance to organophosphates and pyrethroids. Molecular screening for common insecticide target-site mutations confirmed the absence of the 'knockdown resistance' response for pyrethroid insecticide in Ae. albopictus population, suggesting its continual effectiveness as the major insecticide of significant importance in future vector-control programmes.

CONCLUSION

This is the first report of a kdr mutation in Ae. albopictus in India and highlights the need for intensive research on other unexplored target-site mutations that might also contribute to pyrethroid resistance. Effective management and sustainable use of insecticides can be implemented by understanding resistance mechanisms and development of appropriate diagnostic tools. © 2017 Society of Chemical Industry.

Tm-Shift Detection of Dog-Derived Ancylostoma ceylanicum and A. caninum

To develop a T_m-shift method for detection of dog-derived Ancylostoma ceylanicum and A. caninum, three sets of primers were designed based on three SNPs (ITS71, ITS197, and ITS296) of their internal transcribed spacer 1 (ITS1) sequences. The detection effect of the T_m-shift was assessed through the stability, sensitivity, accuracy test, and clinical detection. The results showed that these three sets of primers could distinguish accurately between A. ceylanicum and A. caninum. The coefficient of variation in their T_m values on the three SNPs was 0.09% and 0.15% (ITS71), 0.18% and 0.14% (ITS197), and 0.13% and 0.07% (ITS296), respectively. The lowest detectable concentration of standard plasmids for A. ceylanicum and A. caninum was 5.33 × 10⁻⁶ ng/μL and 5.03 × 10⁻⁶ ng/μL. The T_m-shift results of ten DNA samples from the dog-derived hookworms were consistent with their known species. In the clinical detection of 50 fecal samples from stray dogs, the positive rate of hookworm detected by T_m-shift (42%) was significantly higher than that by microscopic examination (34%), and the former can identify the Ancylostoma species. It is concluded that the T_m-shift method is rapid, specific, sensitive, and suitable for the clinical detection and zoonotic risk assessment of the dog-derived hookworm.

NF-kB2 Genetic Variations are Significantly Associated with Non-Small Cell Lung Cancer Risk and Overall Survival

During the last decade, a growing number of publications implicate NF-kB2 in NSCLC pathogenesis. Here, we investigated the clinical relevance of NF-kB2 single nucleotide polymorphisms (SNPs) rs7897947, rs11574852 and rs12769316 in NSCLC and their association with NF-kB2 protein and mRNA levels. Our data show that TT (rs7897947T >G) and AA (rs12769316G >A) genotypes were strongly associated with an increased risk for NSCLC (P = 0.019 and P = 0.003, respectively). Additionally, in multivariate analysis, TT (rs7897947T >G) homozygosity was associated with worse 2- and 3-year survival rates (P = 0.030 and P = 0.028, respectively), especially among patients with stages III/IV, who had worse 2, 3 and 5-year survival (P = 0.001, P = 0.022 and P = 0.035, respectively). In chemotherapy-treated patients, TT (rs12769316G >A) homozygosity was also associated with worse 2- and 3-year survival compared to G allele carriers (P = 0.006 and P = 0.014, respectively). Furthermore, rs12769316 was correlated with survival outcome of stage I and II patients (P = 0.031 and P = 0.006, respectively). Interestingly, amongst the patients who developed metastases, A allele carriers had better 5-year survival (P = 0.020). In addition, rs12769316 was associated with NF-kB2 protein (P = 0.001) and mRNA expression (P = 0.017) as well as with tumor maximum diameter (P = 0.025). Overall, this study suggests that rs7897947 and rs12769316 are involved in NSCLC susceptibility, in treatment response and in clinical outcome.

Germline variations at JAK2, TERT, HBS1L-MYB and MECOM and the risk of myeloproliferative neoplasms in Taiwanese population

Germline variations at JAK2, TERT, HBS1L-MYB and MECOM have been found to associate with myeloproliferative neoplasms (MPNs) in European populations. Whether these germline variations are associated with MPNs in Taiwanese population is obscure. Here we aimed to evaluate the association of five germline variations (JAK2 46/1 haplotype tagged by rs12343867, JAK2 intron 8 rs12339666, TERT rs2736100, HBS1L-MYB rs9376092 and MECOM rs2201862) and the risk of MPNs in Taiwanese population. A total of 178 MPN patients (109 essential thrombocythemia, 54 polycythemia vera and 15 primary myelofibrosis) were enrolled into this study. The information of 17033 control subjects was obtained from Taiwan Biobank database. The JAK2 46/1 haplotype, JAK2 rs12339666 and TERT rs2736100 were significantly associated with Taiwanese MPNs (P = 3.6×10^-19, 1.9×10^-19 and 3.1×10^-6, respectively), and JAK2^V617F-positive MPNs (n=121) (P = 5.6×10^-21, 4.4×10^-21 and 8.6×10^-7, respectively). In JAK2^V617F-negative cases (n=55), only the JAK2 46/1 haplotype and JAK2 rs12339666 remained statistically significant (P= 0.009 and 0.007, respectively). When stratified by disease subtypes, the JAK2 46/1 haplotype and JAK2 rs12339666 were significantly associated with all three MPN subtypes, but TERT rs2736100 was only associated with essential thrombocythemia and polycythemia vera. We did not find any association of these five SNPs with CALR mutations in our cohort. Furthermore, the risk alleles of MECOM rs2201862 and HBS1L-MYB rs9376092 were demonstrated to be negatively associated with the risk of developing polycythemia vera. In conclusion, germline variations at JAK2 (both the 46/1 haplotype and rs12339666) and TERT rs2736100 were associated with MPNs in Taiwanese population.

Whole-Genome Resequencing Identifies the Molecular Genetic Cause for the Absence of a Gy5 Glycinin Protein in Soybean PI 603408

During ongoing proteomic analysis of the soybean (Glycine max (L.) Merr) germplasm collection, PI 603408 was identified as a landrace whose seeds lack accumulation of one of the major seed storage glycinin protein subunits. Whole genomic resequencing was used to identify a two-base deletion affecting glycinin 5 The newly discovered deletion was confirmed to be causative through immunological, genetic, and proteomic analysis, and no significant differences in total seed protein content were found to be due to the glycinin 5 loss-of-function mutation per se In addition to focused studies on this one specific glycinin subunit-encoding gene, a total of 1,858,185 nucleotide variants were identified, of which 39,344 were predicted to affect protein coding regions. In order to semiautomate analysis of a large number of soybean gene variants, a new SIFT 4G (Sorting Intolerant From Tolerated 4 Genomes) database was designed to predict the impact of nonsynonymous single nucleotide soybean gene variants, potentially enabling more rapid analysis of soybean resequencing data in the future.

First report of the Phe1534Cys kdr mutation in natural populations of Aedes albopictus from Brazil

Background

Knockdown resistance (kdr), caused by alterations in the voltage-gated sodium channel (Na_V), is one of the mechanisms responsible for pyrethroid (PY) resistance. In the Asian tiger mosquito, Aedes albopictus, at least four different mutations were described in the IIIS6 Na_V segment in populations from Asia, North America and Europe. In contrast, in Aedes aegypti at least 12 non-synonymous mutations have been reported at nine different codons, mostly in the IIS6 and IIIS6 Na_V segments. The Phe1534Cys kdr mutation in the IIIS6 Na_V segment is the most prevalent in populations of Ae. aegypti worldwide, also found in Ae. albopictus from Singapore. Herein, we investigated the DNA diversity corresponding to the IIS6 and IIIS6 Na_V segments in natural populations of Ae. albopictus from Brazil.

Methods

DNA from eight Brazilian Ae. albopictus natural populations were individually extracted and pooled by states of origin, amplified, cloned and sequenced for the corresponding IIS6 and IIIS6 Na_V segments. Additionally, samples from each location were individually genotyped by an allelic specific PCR (AS-PCR) approach to obtain the genotypic and allelic frequencies for the 1534 Na_V site.

Results

No non-synonymous substitutions were observed in the IIS6 sequences. However, the Phe1534Cys kdr mutation was evidenced in the Ae. albopictus Na_V IIIS6 segment sequences from Paraná (PR) and Rondônia (RO) states, but not from Mato Grosso (MT) state. The 1534Cys^kdr allele varied from 3% (Marilena/PR and Porto Velho/RO) to 10% (Foz do Iguaçu/PR). To our knowledge, this paper reports the first occurrence and provides distribution data of a possible kdr mutation in Ae. albopictus in South America.

Conclusion

The emergence of a likely kdr mutation in Ae. albopitus natural populations is a signal of alert for vector control measures since PY are the most popular insecticides adopted by residents. Additionally, once the kdr allele is present, its frequency tends to increase faster under exposition to those compounds. Although the Asian tiger mosquito is not incriminated as an important vector of dengue, chikungunya and Zika viruses in South America, its importance in this regard has been extensively discussed since Ae. albopictus is rapidly spreading and can also migrate between sylvatic and urban environments. Therefore, insecticide resistance monitoring initiatives should also be extended to Ae. albopictus in Brazil in order to maintain chemical compounds as an efficient vector control tool when needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2089-5) contains supplementary material, which is available to authorized users.

Analysis of Association of Angiotensin II Type 1 Receptor Gene A1166C Gene Polymorphism with Essential Hypertension

The A/C transversion at 1166 of the angiotensin II Type 1 Receptor (AT1R) gene per se does not characterize any functional diversity but has been associated with expression of the AT1R, consequently molecular variants of the gene may modulate the possible risk of essential hypertension. The present study was performed to determine the genotypic frequency of the A1166C polymorphism of the AT1R gene in essential hypertensive patients with the aim to assess the effect of variants of this polymorphism in hypertension. AT1R gene amplification was performed by PCR and A1166C polymorphism was determined by enzyme digestion methodologies in 224 consecutively enrolled essential hypertensive patients and 257 controls. Suitable descriptive statistics was used for different variables. Results revealed that genotype and allele distribution of the A1166C variant differed significantly in hypertensives and normotensives. Allele frequency at the A1166C position was 61%A and 39%C for control and 52%A and 48%C for patients. Observed frequencies were compatible with HWE expected frequencies in cases as well as in controls. rs5186 was found to be associated with hypertension (95% CI 1.1453-2.7932, p: 0.0106). The difference remained statistically significant after the multivariate adjustment (p < 0.05), with C/C variant conferring a risk of 1.74-fold of essential hypertension. This association was confirmed by inter-genotypic variations in the mean systolic and diastolic blood pressure in patients. In conclusion, genetic variation at the AT1R gene influences the risk of hypertension stratification and might serve as a predictive marker for the susceptibility to hypertension among affected families.

Development of T m -shift genotyping method for detection of cat-derived Giardia lamblia

To develop T _m -shift genotyping method for detection of cat-derived Giardia lamblia, two sets of primers with two GC-rich tails of unequal length attached to their 5'-end were designed according to two SNPs (BG434 and BG170) of β-giardin (bg) gene, and specific PCR products were identified by inspection of a melting curve on real-time PCR thermocycler. A series of experiments on the stability, sensitivity, and accuracy of T _m -shift method was tested, and clinical samples were also detected. The results showed that two sets of primers based on SNP could distinguish accurately between assemblages A and F. Coefficient of variation of T _m values of assemblage A and F was 0.14 and 0.07% in BG434 and 0.10 and 0.11% in BG170, respectively. The lowest detection concentration was 4.52 × 10^-5 and 4.88 × 10^-5 ng/μL samples of assemblage A and F standard plasmids. The T _m -shift genotyping results of ten DNA samples from the cat-derived G. lamblia were consistent with their known genotypes. The detection rate of clinical samples by T _m -shift was higher than that by microscopy, and their genotyping results were in complete accordance with sequencing results. It is concluded that the T _m -shift genotyping method is rapid, specific, and sensitive and may provide a new technological mean for molecular detection and epidemiological investigation of the cat-derived G. lamblia.

Modified low cost SNP genotyping technique using cycle threshold (Ct) & melting temperature (Tm) values in allele specific real-time PCR

Background & objectives:

Genotyping has now become one of the major diagnostic means for almost all diseases. Among the advanced techniques that are used to study single nucleotide polymorphisms (SNPs), only a few are applicable for routine disease diagnosis. Their applicability mainly depends on three factors: cost, time, and accuracy. The primary objective of this study was to propose allele-specific real-time PCR as a rapid, low cost and simple genotyping method for routine diagnostics.

Methods:

Two SNPs, rs3014866 and rs2149356 were analysed using allele-specific real-time PCR. The polymerase chain reaction was carried out using RealQ PCR master mix containing SYBR Green DNA I dye followed by melt curve analysis. The results were validated by agarose gel electrophoresis and DNA sequencing.

Results:

The allelic discrimination and zygosity of the two SNPs were assessed by combined cycle threshold (Ct) and melting temperature (T_m) values. Variations in Ct and T_m values among the two alleles were observed in both rs3014866 (Ct: C allele - 24±1, T allele - 27±1; T_m: C allele - 82.5±0.3, T allele - 86.3±0.2) and rs2149356 (Ct: C allele - 24±1, A allele - 26±1; T_m: C allele - 79.4±0.2, A allele - 80.4±0.3). Based on the variations, homozygous and heterozygous alleles were detected. Agarose gel electrophoresis and DNA sequencing also confirmed the allelic variation and zygosity observed in real-time PCR.

Interpretation & conclusions:

In diagnostic settings where a large number of samples are analysed daily, allele-specific real-time PCR assay may serve as a simple, low cost and efficient method of genotyping.

Anxiety and depression with neurogenesis defects in exchange protein directly activated by cAMP 2-deficient mice are ameliorated by a selective serotonin reuptake inhibitor, Prozac

Intracellular cAMP and serotonin are important modulators of anxiety and depression. Fluoxetine, a selective serotonin reuptake inhibitor (SSRI) also known as Prozac, is widely used against depression, potentially by activating cAMP response element-binding protein (CREB) and increasing brain-derived neurotrophic factor (BDNF) through protein kinase A (PKA). However, the role of Epac1 and Epac2 (Rap guanine nucleotide exchange factors, RAPGEF3 and RAPGEF4, respectively) as potential downstream targets of SSRI/cAMP in mood regulations is not yet clear. Here, we investigated the phenotypes of Epac1 (Epac1(-/-)) or Epac2 (Epac2(-/-)) knockout mice by comparing them with their wild-type counterparts. Surprisingly, Epac2(-/-) mice exhibited a wide range of mood disorders, including anxiety and depression with learning and memory deficits in contextual and cued fear-conditioning tests without affecting Epac1 expression or PKA activity. Interestingly, rs17746510, one of the three single-nucleotide polymorphisms (SNPs) in RAPGEF4 associated with cognitive decline in Chinese Alzheimer's disease (AD) patients, was significantly correlated with apathy and mood disturbance, whereas no significant association was observed between RAPGEF3 SNPs and the risk of AD or neuropsychiatric inventory scores. To further determine the detailed role of Epac2 in SSRI/serotonin/cAMP-involved mood disorders, we treated Epac2(-/-) mice with a SSRI, Prozac. The alteration in open field behavior and impaired hippocampal cell proliferation in Epac2(-/-) mice were alleviated by Prozac. Taken together, Epac2 gene polymorphism is a putative risk factor for mood disorders in AD patients in part by affecting the hippocampal neurogenesis.

A protocol of homozygous haploid callus induction from endosperm of Taxus chinensis Rehd. var. mairei

Obtainment and characterization of the novel endosperm callus of Taxus chinensis Rehd. var. mairei are valuable for haploid breeding, genome, and functional genome in Taxus. Callus was obtained by hydropriming with sterile water for 3 days and suitable medium composition. The highest callus induction (70.89 %) and lower browning ratio (7.95 %) were obtained from Gamborg (B5) medium supplemented with 30 g l(-1) of sucrose, 2.5 mg l(-1) of 2,4-dichlorophenoxyacetic (2,4-D), 0.5 mg l(-1) of 6-benzylademine (6-BA) and 7 g l(-1) of agar under dark conditions. The auxin of 2,4-D had a better efficiency of callus induction than naphthylacetic acid, and over 1 mg l(-1) of 6-BA was inhibitory to the callogensis of endosperm. The endosperm callus was haploid which was detectable by the flow cytometry. The genome block of homozygosity of callus was homozygous which was indicated by PCR-based SNP marks. The homozygous haploid of endosperm callus in vitro culture may be useful tools for taxoid-metabolism of gene engineering and bio-fermentation engineering.

Association of gene expression and methylation of UQCRC1 to the predisposition of Alzheimer's disease in a Chinese population

DNA methylation is an important epigenetic mechanism for gene regulation and it is well established there is association between aging and DNA methylation. Alzheimer's disease (AD) is the most common neurodegenerative disease, characterized by amyloid plaque deposition and formation of neurofibrillary tangles. In this study, we examined the correlation between DNA methylation and gene expression of seven genes including CTSB, CTSD, DDT, TSC1, NRD1, UQCRC1 and NDUFA6 and its effect on the risk of AD in a Chinese population. Our finding showed significantly increased gene expression of these 7 genes in AD patients (2.7-fold-8.6-fold). UQCRC1 was highly methylated in AD patients and there was strong positive correlation between gene expression level and methylation status of UQCRC1 (p < 0.001). Further analysis showed the methylation status of UQCRC1 was significantly associated with gene expression of NRD1, DDT, CTSB and CTSD, suggested the regulatory mechanism on these 4 genes by UQCRC1. Our study further suggested the role of methylation in gene regulation and the role in AD.

Development of a Melting Curve-Based Allele-Specific PCR of Apolipoprotein E (APOE) Genotyping Method for Genomic DNA, Guthrie Blood Spot, and Whole Blood

Genetic polymorphisms of apolipoprotein E (APOE) are associated with various health conditions and diseases, such as Alzheimer's disease, cardiovascular diseases, type 2 diabetes, etc. Hence, genotyping of APOE has broad applications in biomedical research and clinical settings, particularly in the era of precision medicine. The study aimed to develop a convenient and accurate method with flexible throughput to genotype the APOE polymorphisms. A melting curve-based allele-specific PCR method was developed to genotype two single nucleotide polymorphisms (SNPs) of APOE, i.e. rs429358 at codon 112 and rs7412 at codon 158. These two SNPs determine the genotype of APOE2, E3, and E4. PCR-based Sanger sequencing was used as the reference method for APOE genotyping. A 100% concordance rate was obtained in 300 subjects between the melting curve-based allele-specific PCR method and the Sanger sequencing method. This method was applied to a genetic association analysis of APOE and schizophrenia consisting of 711 patients with schizophrenia and 665 control subjects from Taiwan. However, no significant differences in the allele and genotype frequencies were detected between these two groups. Further experiments showed that DNA dissolved from blood collected on Guthrie filter paper and total blood cell lysate without DNA extraction can be used in the melting curve-based allele-specific PCR method. Thus, we suggest that this is a fast, accurate and robust APOE genotyping method with a flexible throughput and suitable for DNA template from different preparations. This convenient method shall meet the different needs of various research and clinical laboratories.

Detection of HER2 Gene Polymorphism in Breast Cancer: PCR Optimization Study

Cancers are the most deadly diseases in the world and their incidences continue to increase over time. Particularly, breast cancer in females places 1^st rank among other types of cancers in term of cancer cases (23%) and death incidence (14%). Recent findings support the correlation between ^Ile655^Val SNP in the HER2 gene with breast cancer risk. Moreover, the ^Ile655^Val HER2 gene polymorphism could be a predictive factor in a neoadjuvant therapy setting. Precise detection of the ^Ile655^Val HER2 gene SNP in early breast cancer patients will be beneficial in designing the most suitable treatment and in increasing the efficacy of anticancer drugs. Here we develop a rapid and inexpensive method for ^Ile655^Val SNP detection in the HER2 gene based on allele-specific PCR technology. Two forward primers and one common reverse primer were designed to anneal specifically either on the HER2 gene fragment containing the GG genotype or to the HER2 gene fragment containing the AA genotype where one of these primers had been added with poly-GC at 5’ upstream. Moreover, to increase discrimination level, mismatch bases at the SNP site and the 3^rd base of each forward primers from 3’end were added. To test the performance of the designed primers in discriminating a polymorphism and its annealing temperature, breast cancer specimen-derived genomic DNA (with GG genotype) and pGEM_HER2/AA (with AA genotype) were used as templates in the PCR reaction. The optimal annealing temperature for SNP detection was at 51.5°C as showed by the appearance of a 150 base pair (bp) band as AA genotype (pGEM_HER2/AA template), 116bp band as GG genotype (genomic DNA template), and both types of bands as AG genotype (mix of pGEM_HER2/AA and genomic DNA template). Allelic types of breast cancer patients were also determined using this optimized method compared to sanger sequencing. The 100% accordance was shown for all types of genotypes in both methods. The allele-specific PCR in this study may have application in determining polymorphisms of the breast cancers-originated ^Ile655^Val HER2 gene.

Gender-Specific Association of ATP2B1 Variants with Susceptibility to Essential Hypertension in the Han Chinese Population

Previous genome-wide association studies (GWASs) found that several ATP2B1 variants are associated with essential hypertension (EHT). But the "genome-wide significant" ATP2B1 SNPs (rs2681472, rs2681492, rs17249754, and rs1105378) are in strong linkage disequilibrium (LD) and are located in the same LD block in Chinese populations. We asked whether there are other SNPs within the ATP2B1 gene associated with susceptibility to EHT in the Han Chinese population. Therefore, we performed a case-control study to investigate the association of seven tagSNPs within the ATP2B1 gene and EHT in the Han Chinese population, and we then analyzed the interaction among different SNPs and nongenetic risk factors for EHT. A total of 902 essential hypertensive cases and 902 normotensive controls were involved in the study. All 7 tagSNPs within the ATP2B1 gene were retrieved from HapMap, and genotyping was performed using the Tm-shift genotyping method. Chi-squared test, logistic regression, and propensity score analysis showed that rs17249754 was associated with EHT, particularly in females. The MDR analysis demonstrated that the interaction of rs2070759, rs17249754, TC, TG, and BMI increased the susceptibility to hypertension. Crossover analysis and stratified analysis indicated that BMI has a major effect on the development of hypertension, while ATP2B1 variants have a minor effect.

Primer design for PCR reactions in forensic biology

The polymerase chain reaction (PCR) is a popular method to copy DNA in vitro. Its invention revolutionized fields ranging from clinical medicine to anthropology, molecular biology, and forensic biology. The method employs one of many available heat-stable DNA polymerases in a reaction that is repeated many times in situ. The DNA polymerase reads a template DNA strand and using the components of the reaction mix, catalyzes the addition of free 2'-deoxynucleotide triphosphate nitrogenous bases to short segment of DNA that forms a complement with the template via Watson-Crick base pairing. This short segment of DNA is referred to as a PCR primer and it is essential to the success of the reaction. The most widely used application of PCR in forensic labs is the amplification of short tandem repeat (STR) loci used in DNA typing. The STRs are routinely evaluated in concert with 16 or more reactions, a multiplex, run in one test tube simultaneously. In a multiplex, it is essential that the primers work specifically and accurately on the intended reactions without hindering the other reactions. The primers, which are very specific, also can be used to probe single nucleotide polymorphisms (SNPs) in a DNA sequence of interest by single base extension. Primers are often designed using one of many available automated software packages. Here the process of manually designing PCR primers for forensic biology using no-cost software is described.

Variant of BCL3 gene is strongly associated with five-year survival of non-small-cell lung cancer patients

OBJECTIVES

BCL3, a known atypical IκB family member, has been documented to be upregulated in hematological malignancies and in some solid tumors, functioning as a crucial player in tumor development. Recently, rs8100239, a tag-Single Nucleotide Polymorphism (SNP) in BCL3 (T>A) has been identified, but there are no data regarding its involvement in non-small-cell lung cancer (NSCLC) initiation and progression.

MATERIALS AND METHODS

To study the possible association of BCL3 with NSCLC, 268 patients and 279 healthy controls were genotyped for rs8100239. Moreover, BCL3 protein expression was also investigated in 112 NSCLC cases through an immunohistochemical analysis.

RESULTS

NSCLC patients with AA genotype displayed significantly worse prognosis compared to T allele carriers (P<0.001), who had less frequent intermediate nuclear BCL3 expression (P=0.042). In addition, overexpression of BCL3 was detected in tumor specimens, compared to normal tissue (P<0.001). Furthermore, BCL3 protein levels were associated with five-year survival (P=0.039), maximum diameter of lesion (P=0.012), grade (P=0.002) and relapse frequency (P=0.041).

CONCLUSIONS

The present study is the first to show a relationship between the genetic variation rs8100239 of BCL3 and cancer patients' survival. It also represents the first quantitative evaluation of BCL3 expression in NSCLC. Our findings indicate that rs8100239 may be considered as a novel prognostic indicator, demonstrating also the overexpression of BCL3 protein in NSCLC and implicating this pivotal molecule in the pathogenesis of NSCLC.

Fine-mapping of a major QTL controlling angular leaf spot resistance in common bean (Phaseolus vulgaris L.)

KEY MESSAGE

A major QTL for angular leaf spot resistance in the common bean accession G5686 was fine-mapped to a region containing 36 candidate genes. Markers have been developed for marker-assisted selection. Common bean (Phaseolus vulgaris L.) is an important grain legume and an essential protein source for human nutrition in developing countries. Angular leaf spot (ALS) caused by the pathogen Pseudocercospora griseola (Sacc.) Crous and U. Braun is responsible for severe yield losses of up to 80%. Breeding for resistant cultivars is the most ecological and economical means to control ALS and is particularly important for yield stability in low-input agriculture. Here, we report on a fine-mapping approach of a major quantitative trait locus (QTL) ALS4.1(GS, UC) for ALS resistance in a mapping population derived from the resistant genotype G5686 and the susceptible cultivar Sprite. 180 F3 individuals of the mapping population were evaluated for ALS resistance and genotyped with 22 markers distributed over 11 genome regions colocating with previously reported QTL for ALS resistance. Multiple QTL analysis identified three QTL regions, including one major QTL on chromosome Pv04 at 43.7 Mbp explaining over 75% of the observed variation for ALS resistance. Additional evaluation of 153 F4, 89 BC1F2 and 139 F4/F5/BC1F3 descendants with markers in the region of the major QTL delimited the region to 418 kbp harboring 36 candidate genes. Among these, 11 serine/threonine protein kinases arranged in a repetitive array constitute promising candidate genes for controlling ALS resistance. Single nucleotide polymorphism markers cosegregating with the major QTL for ALS resistance have been developed and constitute the basis for marker-assisted introgression of ALS resistance into advanced breeding germplasm of common bean.

A lack of association between the IKZF2 rs12619285 polymorphism and coronary heart disease

The IKZF2 rs12619285 polymorphism is associated with the eosinophil count, which has multidimensional functions in the pathogenesis of coronary heart disease (CHD). The aim of the present study was to investigate the contribution of the IKZF2 rs12619285 polymorphism to the risk of CHD in a Han Chinese population. In total, 721 CHD cases and 631 non-CHD controls were recruited for an association study of the IKZF2 rs12619285 polymorphism. Genotyping was performed using the melting temperature-shift polymerase chain reaction method. No statistically significant association was observed between the IKZF2 rs12619285 polymorphism and CHD (odds ratio, 1.139, 95% confidence interval, 0.927-1.334; P=0.17). In addition, subgroup analyses by gender or age were unable to identify any association between IKZF2 rs12619285 and CHD (P>0.05), and there was no significant correlation between IKZF2 rs12619285 and the severity of CHD (P>0.05). The power of the case-control study was determined to be 63.3%. In addition, the G allele frequency was calculated as 63.6% in the Han Chinese population, which was similar to the 59.3% recorded for the HapMap Chinese population of Han Chinese individuals living in Beijing, compared with 24.3% in European descendents (HapMap-CEU). Therefore, the results indicated that the IKZF2 rs12619285 polymorphism was not associated with CHD in a Han Chinese population. The discrepancy in the association between rs12619285 and CHD may be due to the ethnic differences between Han Chinese and European populations.

PPARD rs2016520 polymorphism and circulating lipid levels connect with brain diseases in Han Chinese and suggest sex-dependent effects

The PPARD polymorphisms were shown to be associated with circulating lipoprotein metabolism in various diseases. We aimed to check the contribution of PPARD rs2016520 and lipid concentration to the risk of intracerebral hemorrhages (ICH) and brain tumors (BT) in Han Chinese. A total of 864 participants were included in the case-control study. The melting temperature shift (Tm-shift) method was used for rs2016520 genotyping. Under the recessive model, PPARD rs2016520 was shown to be associated with the risk of ICH (P=0.029, odds ratio (OR)=2.72), specifically in males (P=0.045, OR=3.98). Additionally, we also found that the levels of TC and LDL-C were significantly higher in participants with brain diseases than in the controls (TC: P<0.0001; LDL-C: P<0.0001). Significantly higher HDL-C and lower ApoA-I levels were observed in the male patients with brain diseases (HDL-C: P<0.0001; ApoA-I: P=0.008), in contrast of a higher TG level in female ICH (P=0.023). Subsequent interaction analysis between PPARD rs2016520 and lipoprotein metabolism showed that the LDL-C level was positively correlated with ICH in the rs2016520-AA carriers (P<0.0001), but not in the other genotype carriers (AG or GG, P=0.300). Our results showed that PPARD rs2016520 displayed a strong relationship with ICH risk in the male Han Chinese. The TC and LDL-C levels were positively higher in the patients with brain diseases than in the controls. The levels of TG, HDL-C and ApoA-I were shown to affect brain disease in a gender-dependent model. The genotype rs2016520-AA showed significant interaction with the circulating LDL-C levels in ICH.

BDNF mediates improvements in executive function following a 1-year exercise intervention

Executive function declines with age, but engaging in aerobic exercise may attenuate decline. One mechanism by which aerobic exercise may preserve executive function is through the up-regulation of brain-derived neurotropic factor (BDNF), which also declines with age. The present study examined BDNF as a mediator of the effects of a 1-year walking intervention on executive function in 90 older adults (mean age = 66.82). Participants were randomized to a stretching and toning control group or a moderate intensity walking intervention group. BDNF serum levels and performance on a task-switching paradigm were collected at baseline and follow-up. We found that age moderated the effect of intervention group on changes in BDNF levels, with those in the highest age quartile showing the greatest increase in BDNF after 1-year of moderate intensity walking exercise (p = 0.036). The mediation analyses revealed that BDNF mediated the effect of the intervention on task-switch accuracy, but did so as a function of age, such that exercise-induced changes in BDNF mediated the effect of exercise on task-switch performance only for individuals over the age of 71. These results demonstrate that both age and BDNF serum levels are important factors to consider when investigating the mechanisms by which exercise interventions influence cognitive outcomes, particularly in elderly populations.

The relationship between SNPs in the genes of TLR signal transduction pathway downstream elements and rheumatoid arthritis susceptibility

Toll-like receptors (TLRs) play an important role in the induction and regulation of the innate immune system or adaptive immune responses. Genetic variations within human TLRs have been reported to be associated with rheumatoid arthritis (RA). This study was conducted to investigate correlation between SNP of downstream mononucleotide in signal transduction of Toll-like receptors and predisposing genes of RA. There was obviously correlative between single nucleotide polymorphism and predisposing genes of RA. G-type of IL-1RAP rs766442 may be protecting genes of RA, while T-type alleles of IL-6R rs11265618 and IL-1RAP rs766442 may be susceptible genes of RA. In conclusion, the studies on the nucleis acid polymorphism in TLRs signal pathway contribute to disclose genes' influence on the attack mechanism of RA, early diagnosis and treatment of RA.