PCR-based Genotyping Method Research Articles

Shotgun DNA sequencing for human identification: Dynamic SNP selection and likelihood ratio calculations accounting for errors

Shotgun sequencing is a DNA analysis method that potentially determines the nucleotide sequence of every DNA fragment in a sample, unlike PCR-based genotyping methods that is widely used in forensic genetics and targets predefined short tandem repeats (STRs) or predefined single nucleotide polymorphisms (SNPs). Shotgun DNA sequencing is particularly useful for highly degraded low-quality DNA samples, such as ancient samples or those from crime scenes. Here, we developed a statistical model for human identification using shotgun sequencing data and developed formulas for calculating the evidential weight as a likelihood ratio (LR). The model uses a dynamic set of binary SNP loci and takes the error rate from shotgun sequencing into consideration in a probabilistic manner. To our knowledge, the method is the first to make this possible. Results from replicated shotgun sequencing of buccal swabs (high-quality samples) and hair samples (low-quality samples) were arranged in a genotype-call confusion matrix to estimate the calling error probability by maximum likelihood and Bayesian inference. Different genotype quality filters may be applied to account for genotyping errors. An error probability of zero resulted in the commonly used LR formula for the weight of evidence. Error probabilities above zero reduced the LR contribution of matching genotypes and increased the LR in the case of a mismatch between the genotypes of the trace and the person of interest. In the latter scenario, the LR increased from zero (occurring when the error probability was zero) to low positive values, which allow for the possibility that the mismatch may be due to genotyping errors. We developed an open-source R package, wgsLR, which implements the method, including estimation of the calling error probability and calculation of LR values. The R package includes all formulas used in this paper and the functionalities to generate the formulas.

A novel PCR-based genotyping method for Proteus mirabilis – Intergenic region polymorphism analysis

Proteus mirabilis is a predominant species in cases of food poisoning associated with meat products and is also an opportunistic pathogen causing numerous infections in humans. This study aimed to differentiate P. mirabilis isolates using intergenic region polymorphism analysis (IRPA). The IRPA typing scheme was developed to amplify polymorphic fragments in intergenic regions (IGRs). The presence, absence, or size change of amplified products were identified and utilized as genetic markers for rapid differentiation of strains. A total of 75 P. mirabilis isolates were isolated from 63 fresh poultry and pork samples were subtyped using the IRPA and ERIC-PCR methods, and their antibiotic resistance profiles were tested. The majority of P. mirabilis isolates showed resistance to tetracycline (85.3%), doxycycline (93.3%), chloramphenicol (82.7%), streptomycin (92.0%), spectinomycin (80.0%), trimethoprim (97.3%); trimethoprim-sulfalleth (82.7%), and erythromycin (100.0%). In contrast, resistance rates to ceftriaxon, cefoxitin, cefepime, and cefotaxim were lower at only 17.3%, 5.3%, 6.7%, and 13.3%, respectively, among P. mirabilis isolates. Eleven loci were selected for analysis of the genetic diversity of 75 P. mirabilis isolates. A combination of 4 loci was determined as the optimal combination. The results compared to those obtained using ERIC-PCR for the same isolates. The Simpson's index of diversity was 0.999 for IRPA and 0.923 for ERIC-PCR, indicating that IRPA has a higher discriminatory power than ERIC-PCR. The concordance between IRPA and ERIC-PCR methods was low, primarily because IRPA classified isolates from the same ERIC cluster into separate clusters due to its high resolution. The IRPA method presented in this study offers a rapid, simple, reproducible, and economical approach for genotyping P. mirabilis.

Antimicrobial resistance profile and prevalence of Mycobacterium tuberculosis complex in Western Iran using spoligotyping method

Tuberculosis (TB) is a chronic infectious disease with multiple manifestations and gradual progression that remains a major health problem and a leading cause of death worldwide. In recent years, a number of DNA fingerprinting techniques have been developed to identify strains of the Mycobacterium tuberculosis (MTB) complex. Spoligotyping is one of the first PCR-based genotyping methods. Information on the number and identification of common strains among MTB complex samples in clinical samples from Kermanshah city is needed to develop more effective therapeutic strategies.This is a descriptive cross-sectional study of 41 sample patients with TB referred to Kermanshah Tuberculosis Centre between December 2021 and June 2022, including sputum, aspiration, urine, etc. First, the susceptibility of the developed bacteria to culture media was compared with that of isoniazid using the proportional method, and rifampin was determined according to the standard protocol. Demographic data of patients referred to the Centre for the Control of Lung Diseases were also recorded.In the next step, spoligotyping was carried out using the standard method and each strain pattern was recorded as an OCTAL code and compared with the information available at the World Bank on spoligotyping and its strains. Forty-one patients with pulmonary TB were tested using spoligotyping. Four MTB strains were identified, including H4, CAS, T1 and H1.The H4 strain also had the highest frequency with 16 samples (39%) among the MTB complex strains isolated using spoligotyping.The highest frequency of strains isolated using spoligotyping was associated with the H4 strain. It can be concluded that spoligotyping is very cost effective, simple, repeatable and highly sensitive.

DEVELOPMENT OF PCR-BASED GENOTYPING METHOD FOR FAT MASS OBESITY-ASSOCIATED (FTO) GENE POLYMORPHISM RS9939609

Malaysia has the highest obesity rate in Southeast Asia and is growing. Environmental and genetic factors influence weight increase and obesity, leading to numerous diseases and mortality. This study aimed to develop a genotyping method to detect FTO gene variant rs9939609, known for its association with body mass index (BMI) and obesity. In-house primers detected rs9939609. Two common primers flanked the variation region, and two more primers identified the wild type and alternative allele. Capillary sequencing verified results. We developed FTO gene variant rs9939609 genotyping. This method can be used to genotype FTO variant rs9939609 in any research.

Genotyping of Salmonella enterica strains from animal and human origin using three molecular techniques

This study aims to characterize different Salmonella enterica subsp molecularly. enterica strains (n=49) were isolated from human gastrointestinal cases in the Tolima region and poultry from Santander and Tolima regions using PCR-RFLP, PCR-ribotyping, and PCR-SSCP. The band patterns obtained with each technique were analyzed by building dendrograms based on the Unweighted Pair Group Method with Arithmetic mean (UPGMA) method and using the Dice coefficient. On the other hand, the discriminatory power of each technique was assessed using Simpson's discriminatory index. The genetic profiles of the gnd gene obtained with AciI restriction enzyme and the PCR-SSCP carried out with groEL gene allowed the inter-and intraserovar differentiation. Finally, the PCR-ribotyping method exhibited the highest discriminatory power (0.8571). In conclusion, we show three PCR-based genotyping methods providing an alternative for identifying similarities and differences within Salmonella enterica strains from different geographic and biological regions.

A simple and rapid method for fish sex identification based on recombinase-aided amplification and its use in Cynoglossus semilaevis

Fish sex identification is a basic technique of great importance for both fish genetic studies and fisheries. Due to the sexual reversal phenomenon in many fish species, a simple and rapid molecular identification method for fish genetic sex is urgently needed to suit versatile detection scenarios, such as point-of-need applications. In this study, we took Cynoglossus semilaevis as an example, established a recombinase-aided amplification (RAA)-based method for sex identification, and combined the RAA-detection with two result visualization approaches with distinct features, capillary electrophoresis (CE) and lateral flow dipstick (LFD). Specific primers and probe were designed to specifically detect the sex chromosome W of C. semilaevis in order to distinguish the genetic sex between males, pseudo-males and females. To evaluate the performance of our methods, the genetic sex for twenty-eight males, sixty-eight pseudo-males and fifty-four females were examined with the RAA-based method and classical PCR-based genotyping method, demonstrating the consistent results of sex identification between both methods. The RAA-LFD method is operationally simple, rapid (~ 30 min) and holds great potential for point-of-need applications of fish sex identification, including fishery fields. The method presented here could be effective for identifying fish gender with the ZW karyotype.

Sequencing of the Canine Cytochrome P450 CYP2C41 Gene and Genotyping of Its Polymorphic Occurrence in 36 Dog Breeds.

Cytochrome P450 (CYP) drug metabolizing enzymes play an important role in efficient drug metabolism and elimination. Many CYPs are polymorphic and, thereby, drug metabolism can vary between individuals. In the case of canine CYP2C41, gene polymorphism was identified. However, as the first available canine genome sequences all were CYP2C41 negative, this polymorphism could not be clarified at the genomic level. The present study provides an exact characterization of the CYP2C41 gene deletion polymorphism at the genomic level and presents a PCR-based genotyping method that was used for CYP2C41 genotyping of 1,089 individual subjects from 36 different dog breeds. None of the Bearded Collie, Bernese Mountain, Boxer, Briard, French Bulldog or Irish Wolfhound subjects had the CYP2C41 gene in their genomes. In contrast, in the Chinese Char-Pei, Siberian Husky, Schapendoes and Kangal breeds, the CYP2C41 allele frequency was very high, with values of 67, 57, 43, and 34%, respectively. Interestingly, the site of gene deletion was identical for all CYP2C41 negative dogs, and all CYP2C41 positive dogs showed highly homologous sequence domains upstream and downstream from the CYP2C41 gene. CYP2C41 genotyping can now be routinely used in future pharmacokinetic studies in canines, in order to identify genetically-based poor or extensive drug metabolizers. This, together with more extensive in vitro drug screening for CYP2C41 substrates will help to determine the clinical relevance of CYP2C41, and to optimize drug treatment. Although the relative abundance of the CYP2C41 protein in the canine liver seems to not be very high, this CYP could substantially contribute to hepatic drug metabolism in dogs expressing CYP2C41 from both alleles and, when CYP2C41 shows higher catalytic activity to a given drug than other hepatic metabolic enzymes.

Полимеразная цепная реакция в реальном времени как метод быстрого генотипирования пациенток с миомой матки на примере трех генетических полиморфизмов

Study Objective: To assess the efficacy of methods for DNA gene typing (direct sequencing and two variants of real-time PCR) for routine analysis of large groups; to compare the prevalence of genotypes of three single nucleotide polymorphisms in groups of women with uterine leiomyoma (with a separate analysis of a group with a family history of the disease) and in controls. Study Design: comparative study. Materials and Methods. Subjects were divided into groups using the case-control principle. DNA gene typing results for two groups of patients were analysed. Also, we analysed prevalence of genotypes in study group (patients with uterine leiomyoma) and in controls (patients without a history of uterine leiomyoma and a family history of the disease). The primary method used for genotyping was direct sequencing with genotype imaging. On the second stage, we tested two different PCR-based genotyping methods. Study Results. Patients with uterine leiomyoma were subject to genotyping using three single nucleotide polymorphisms (rs3020434, rs124577644, rs12637801) in ESR1, FBN2, and KCWMB2 introns. We have identified significant differences in prevalence of genotypes between the study group and controls. Polymorphism prevalence is statistically different between patients with leiomyomas, controls and women with a family history of the disease. It is demonstrated that the use of the two variants of real-time PCR testing instead of direct sequencing speeds up results; these methods are a less expensive and less labour-intensive tool for genotyping of single nucleotide polymorphisms in large groups. Conclusion. Real-time PCR testing can be used for express and efficient analysis of single nucleotide polymorphisms associated with uterine leiomyoma. Both methods (PCR genotyping with the use of oligonucleotide probes and analysis of high-resolution melting profiles) tested in this paper make it possible to get unambiguous results in 97–99% of samples. Keywords: uterine leiomyoma, single nucleotide polymorphisms, family proneness.

Ectopic germline recombination activity of the widely used Foxp3-YFP-Cre mouse: a case report.

Regulatory T (Treg) cell-specific deletion of a gene of interest is a procedure widely used to study mechanisms controlling Treg development, homeostasis and function. Accordingly, several transgenic mouse lines have been generated that bear the Cre recombinase under control of the Foxp3 promoter either as a random transgene insertion or knocked into the endogenous Foxp3 locus, with the Foxp3YFP-Cre strain of mice being one of the most widely used. In an attempt to generate Treg cells that lacked expression of the insulin receptor (Insr), we crossed Foxp3YFP-Cre mice with Insrfl/fl mice. Using a conventional two-band PCR genotyping method we found that offspring genotypes did not correspond to the expected Mendelian ratios. We therefore developed a quantitative PCR-based genotyping method to investigate possible ectopic recombination outside the Treg lineage. With this method we found that ~50% of the F1 -generation mice showed evidence of ectopic recombination and that ~10% of the F2 -generation mice had germline Cre recombination activity leading to a high frequency of offspring with global Insr deletion. Use of the quantitative PCR genotyping method enabled accurate selection of mice without ectopic recombination and only the desired Treg cell-specific Insr deletion. Our data highlight the need to use genotyping methods that allow for assessment of possible ectopic recombination driven by the Foxp3YFP-Cre allele, particularly when studying genes that are systemically expressed.

Reverse Genetic Analysis of Antiviral Resistance Signaling and the Resistance Mechanism in Arabidopsis thaliana.

Antiviral RNA silencing and the resistance gene-conferred defense response are major antiviral immune systems in plants. Several of the components involved have been genetically or biochemically identified in Arabidopsis thaliana. One powerful tool to dissect antiviral immune systems involves a reverse genetic approach that analyzes Arabidopsis mutant lines with impaired antiviral defense responses. In particular, to better understand the signaling networks involved in the resistance gene-conferred antiviral response in host plants, establishment of mutant lines carrying the homozygous mutant allele and antiviral resistance gene is required. The information on well-characterized defense-related signaling mutant alleles and the PCR-based genotyping method provided in this chapter allows the efficient selection of Arabidopsis mutant lines that can be used to study antiviral resistance signaling networks and resistance mechanisms.

Phylogenetic Characterization of Salmonella enterica Serovar Typhimurium and Its Monophasic Variant Isolated from Food Animals in Japan Revealed Replacement of Major Epidemic Clones in the Last 4 Decades.

Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) and its monophasic variant (Salmonella 4,[5],12:i:-) are the major causes of gastroenteritis in both humans and animals. Pulsed-field gel electrophoresis and multilocus variable-number tandem-repeat analysis have been used widely as subtyping methods for these pathogens in molecular epidemiological analyses, but the results do not precisely reflect phylogenetic information. In this study, we performed a phylogenetic analysis of these serovars using whole-genome sequencing data and identified nine distinct genotypic clades. Then, we established an allele-specific PCR-based genotyping method detecting a clade-specific single nucleotide polymorphism to rapidly identify the clade of each isolate. Among a total of 815 isolates obtained from cattle in Japan between 1977 and 2017, clades 1, 7, and 9 contained 77% of isolates. Obvious replacement of the dominant clone was observed five times in this period, and clade 9, which mostly contains Salmonella 4,[5],12:i:-, is currently dominant. Among 140 isolates obtained from swine in Japan between 1976 and 2017, clades 3 and 9 contained 64% of isolates. Clade 9 is the latest clone as is the case in cattle isolates. Clade 9 is similar to an epidemic clone from Europe, which is characterized by sequence type 34 (ST34), chromosomal Salmonella genomic island 3, and a composite transposon containing antimicrobial resistance genes. The increased prevalence of clade 9 among food animals in Japan might be a part of the pandemic of the European Salmonella 4,[5],12:i:- clone.

Impact of inter-genotypic recombination and probe cross-reactivity on the performance of the Abbott RealTime HCV Genotype II assay for hepatitis C genotyping

The Abbott RealTime HCV Genotype II assay (Abbott-RT-HCV assay) is a real-time PCR based genotyping method for hepatitis C virus (HCV). This study measured the impact of inter-genotypic recombination and probe cross-reactivity on the performance of the Abbott-RT-HCV assay. 517 samples were genotyped using the Abbott-RT-HCV assay over a one-year period, 34 (6.6%) were identified as HCV genotype 1 without further subtype designation raising the possibility of inaccurate genotyping. These samples were subjected to confirmatory sequencing. 27 of these 34 (79%) samples were genotype 1b while five (15%) were genotype 6. One HCV isolate was an inter-genotypic 1a/4o recombinant. This is a novel natural HCV recombinant that has never been reported. Inter-genotypic recombination and probe cross-reactivity can affect the accuracy of the Abbott-RT-HCV assay, both of which have significant implications on antiviral regimen choice. Confirmatory sequencing of ambiguous results is crucial for accurate genotyping.

Genotypic and phenotypic characterization of Salmonella enterica subsp. enterica serovar Typhimurium monophasic variants isolated in Thailand and Japan.

Monophasic variants of Salmonella enterica serovar Typhimurium isolated in Thailand and Japan were characterized to elucidate the genetic basis of the monophasic phenotype, genetic relatedness, and antimicrobial resistance. A total of 20 Salmonella isolates agglutinated with anti-O4 and anti-H:i serum and not agglutinated with either anti-H:1 or anti-H:2 serum were identified as monophasic variants of Salmonella serovar Typhimurium because they harbored IS200, specific to this serovar, and lacked the fljB gene. An allele-specific PCR-based genotyping method that detects a clade-specific single nucleotide polymorphism indicated that seven swine isolates and one human isolate from Thailand were grouped into clade 1; five isolates from layer chicken houses and layer chicken feces from Japan were grouped into clade 8, together with two Salmonella serovar Typhimurium isolates from chicken houses in Japan; and five isolates from swine feces from Thailand and two isolates from layer chicken feces from Japan were grouped into clade 9. Multilocus sequencing typing demonstrated that sequence type (ST) 34 isolates were solely grouped into clade 9. Clade 1 and 8 isolates were assigned as ST19. Pulsed-field gel electrophoresis revealed multiple types within each of the clades. The presence of antimicrobial resistance genes and plasmid replicon type, of the clade 1 and 9 isolates were comparable to those reported for epidemic strains of monophasic variants. Our results suggest that monitoring monophasic variants of serovar Typhimurium is important for understanding of the spread of these variants in Thailand and Japan.

A High-Throughput Standard PCR-Based Genotyping Method for Determining Transgene Zygosity in Segregating Plant Populations.

In crop research programs that implement transgene-based strategies for trait improvement it is necessary to distinguish between transgene homozygous and hemizygous individuals in segregating populations. Direct methods for determining transgene zygosity are technically challenging, expensive, and require specialized equipment. In this report, we describe a standard PCR-based protocol coupled with capillary electrophoresis that can identify transgene homozygous and hemizygous individuals in a segregating population without knowledge of transgene insertion site. PCR primers were designed to amplify conserved T-DNA segments of the 35S promoter, OCS terminator, and NPTII kanamycin resistance gene in the pHellsgate-8 RNAi construct for the Gossypium hirsutum phytochrome A1 gene. Using an optimized multiplexed reaction mixture and an amplification program of only 10 cycles we could discriminate between transgene homozygous and hemizygous cotton control DNA samples based on PCR product peak characteristics gathered by capillary electrophoresis. The protocol was refined by evaluating segregating transgenic progeny from nine BC1S1 populations derived from crosses between the transgenic cotton parent ‘E-1-7-6’ and other cotton cultivars. OCS PCR product peak height and peak area, normalized by amplification of the native cotton gene GhUBC1, revealed clear bimodal distributions of OCS product characteristics for each BC1S1 population indicating the presence of homozygous and hemizygous clusters which was further confirmed via K-means clustering. BC1S1 plants identified as homozygous or hemizygous were self-fertilized to produce BC1S2 progeny. For the homozygous class, 19/20 BC1S2 families confirmed the homozygous BC1S1 prediction while 21/21 BC1S2 families confirmed the hemizygous prediction of the original parent. This relatively simple protocol provides a reliable, rapid, and high-throughput way of evaluating segregating transgenic populations using methods and equipment common to crop molecular breeding labs.

VacA and cagA genotypes status and antimicrobial resistance properties of Helicobacter pylori strains isolated from meat products in Isfahan province, Iran.

Although Helicobacter pylori has a significant impact on the occurrence of severe clinical syndromes, its exact ways of transmission and origin have not been identified. According to the results of some previously published articles, foods with animal origins play a substantial role in the transmission of H. pylori to humans. The present investigation was carried out to study the vacuolating cytotoxin A (vacA) and cytotoxin associated gene A (cagA) genotypes status and antibiotic resistance properties of H. pylori strains recovered from minced-meat and hamburger samples. A total of 150 meat product samples were collected from supermarkets. All samples were cultured and the susceptive colonies were then subjected to nested-PCR, PCR-based genotyping and disk diffusion methods. 11 out of 150 samples (7.33%) were positive for H. pylori. All the isolates were further identified using the nested-PCR assay. Prevalence of H. pylori in hamburger and minced-meat samples was 1.42% and 12.5%, respectively. S1a, m1a and cagA were the most commonly detected genotypes. The most commonly detected combined genotypes in the H. pylori strains of minced-meat were s1am1a (10%), s1am1b (10%) and s2m1a (10%). Helicobacter pylori strains of meat products harbored the highest levels of resistance against ampicillin (90.90%), erythromycin (72.72%), amoxicillin (72.72%), trimethoprim (63.63%), tetracycline (63.63%), and clarithromycin (63.63%). Hamburger and minced-meat samples may be the sources of virulent and resistant strains of H. pylori. Meat products are possible sources of resistant and virulent strains of H. pylori similar to those vacA and cagA genotypes. Using healthy raw materials and observation of personal hygiene can reduce the risk of H. pylori in meat products.

High-Throughput Genotyping with TaqMan Allelic Discrimination and Allele-Specific Genotyping Assays.

Real-time PCR-based genotyping methods, such as TaqMan allelic discrimination assays and allele-specific genotyping, are particularly useful when screening a handful of single nucleotide polymorphisms in hundreds of samples; either derived from different individuals, tissues, or pre-amplified DNA. Although real-time PCR-based methods such as TaqMan are well-established, alternative methods, like allele-specific genotyping, are powerful alternatives, especially for genotyping short tandem repeat (STR) length polymorphisms. Here, we describe all relevant aspects when developing an assay for a new SNP or STR using either TaqMan or allele-specific genotyping, respectively, such as primer and probe design, optimization of reaction conditions, the experimental procedure for typing hundreds of samples, and finally the data evaluation. Our goal is to provide a guideline for developing genotyping assays using these two approaches that render reliable and reproducible genotype calls involving minimal optimization.

Giving IDs to turtles: SNP markers for assignment of individuals to lineages of the geographically structured Phrynops geoffroanus (Chelidae: Testudines)

We developed forensic nuclear SNPs for the side-necked turtle, Phrynops geoffroanus, using next-generation sequencing-based genotyping. We created a reduced-representation library for 23 individuals representing four previously identified lineages of P. geoffroanus using the ddRAD methodology for sequencing on the IonTorrent PGM. We analyzed the sequence data using the Stacks pipeline. We found 811 loci containing 1380 private SNPs. Of these, 473 were fixed in lineages 1, 2 and 3, or with frequency >0.91 in lineage 4. Seventy-three SNPs could be useful for forensics purpose (assignment of individuals to lineage of origin) using traditional PCR-based genotyping methods.

The Incidence of Tuberculosis Transmission among Family Members and outside Households

The risk of Mycobacterium tuberculosis complex (MTBC) infection is correlated with the concentration of infectious particles and exposure time. In closed populations, healthy people staying in very frequent, close and prolonged contact with a smear-positive person, become infected and represent another link in the chain of transmission of the disease. Therefore, in the fight against tuberculosis, an important element is quick identification of the patient and potentially infected people from his environment. In epidemiological investigation of tuberculosis (TB), family members are brought under special control as they are particularly exposed to transmission of infectious diseases. The study included 150 patients with bacteriologically confirmed tuberculosis who were members of 59 families. In the years 2003-2013 this population represented all TB cases detected in Poland in a family environment.Three PCR-based genotyping methods: spoligotyping, IS6110-Mtb1-Mtb2 PCR and MIRU-VNTR typing were used. Of 150 patients, 138 could be assigned to intra-household transmission on the basis of identical DNA fingerprints upon a combined typing approach. For 12 patients in 6 households, the M. tuberculosis isolates were clearly distinct in individual analysis - IS6110-Mtb1-Mtb2 PCR, spoligotyping or MIRU-VNTR typing or in three genotyping methods, suggesting that these patients were infected by the sources in the community. The analysis confirmed the transmission of tuberculosis among members of 53 families. In the remaining 6 families the source of infection were people outside the households. In all families with young children, strains isolated from them have identical DNA patterns as strains obtained from their adult caregivers. To confirm the transmission of TB in the study population of patients, epidemiological analysis required the addition of a genotyping methods characterised by high discriminatory power.

SNPs markers for the heavily overfished tambaqui Colossoma macropomum, a Neotropical fish, using next-generation sequencing-based de novo genotyping

We developed nuclear SNPs for the heavily overfished tambaqui/cachama negra Colossoma macropomum using next-generation sequencing-based genotyping. We created a reduced-representation library for 30 individuals from Orinoco and Amazon basins following the ddRAD methodology for sequencing on the IonTorrent PGM. We analyzed the sequence data using the software Stacks. We detected 22,476 tags characterized by 7,181 polymorphic sites, recovering 177 loci (268 SNPs) shared between both basins. A significant difference in the allelic frequencies was observed between basins for a subset of these SNPs. Thirty-nine SNPs could be useful for conservation/population genetics using traditional PCR-based genotyping methods.

De novo SNP markers development for the Neotropical gilded catfish Brachyplatystoma rousseauxii using next-generation sequencing-based genotyping

We generated for the first time nuclear SNP loci for the commercially exploited gilded catfish Brachyplatystoma rousseauxii using next-generation sequencing. We implemented double-digest-Restriction-Associated-DNA-based de novo SNP genotyping for 30 individuals (Orinoco and Amazon basins) using the IonTorrent PGM. It was analyzed the sequence reads using the Stacks pipeline. We detected 18,772 tags with 6170 polymorphic sites and 91 SNPs recovered for both basins. A significant divergence in the allele frequencies was observed between basins for some of those SNPs. Information about diversity and other statistics index are presented for these SNPs. Some of them (23) could be useful for population and conservation genetics of this species using traditional PCR-based genotyping methods.