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April 21, 2020

Microsatellite marker set for genetic diversity assessment of primitive Chitala chitala (Hamilton, 1822) derived through SMRT sequencing technology.

In present study, single molecule-real time sequencing technology was used to obtain a validated set of microsatellite markers for application in population genetics of the primitive fish, Chitala chitala. Assembly of circular consensus sequencing reads resulted into 1164 sequences which contained 2005 repetitive motifs. A total of 100 sequences were used for primer designing and amplification yielded a set of 28 validated polymorphic markers. These loci were used to genotype n?=?72 samples from three distant riverine populations of India, namely Son, Satluj and Brahmaputra, for determining intraspecific genetic variation. The microsatellite loci exhibited high level of polymorphism with PIC values ranging from 0.281 to 0.901. The genetic parameters revealed that mean heterozygosity ranged from 0.6802 to 0.6826 and the populations were found to be genetically diverse (Fst 0.03-0.06). This indicated the potential application of these microsatellite marker set that can used for stock characterization of C. chitala, in the wild. These newly developed loci were assayed for cross transferability in another notopterid fish, Notopterus notopterus.


April 21, 2020

The red bayberry genome and genetic basis of sex determination.

Morella rubra, red bayberry, is an economically important fruit tree in south China. Here, we assembled the first high-quality genome for both a female and a male individual of red bayberry. The genome size was 313-Mb, and 90% sequences were assembled into eight pseudo chromosome molecules, with 32 493 predicted genes. By whole-genome comparison between the female and male and association analysis with sequences of bulked and individual DNA samples from female and male, a 59-Kb region determining female was identified and located on distal end of pseudochromosome 8, which contains abundant transposable element and seven putative genes, four of them are related to sex floral development. This 59-Kb female-specific region was likely to be derived from duplication and rearrangement of paralogous genes and retained non-recombinant in the female-specific region. Sex-specific molecular markers developed from candidate genes co-segregated with sex in a genetically diverse female and male germplasm. We propose sex determination follow the ZW model of female heterogamety. The genome sequence of red bayberry provides a valuable resource for plant sex chromosome evolution and also provides important insights for molecular biology, genetics and modern breeding in Myricaceae family. © 2018 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.


April 21, 2020

Bioinformatic analysis of the complete genome sequence of Pectobacterium carotovorum subsp. brasiliense BZA12 and candidate effector screening

AbstractPectobacterium carotovorum subsp. brasiliense (Pcb) is a gram-negative, plant pathogenic bacterium of the soft rot Enterobacteriaceae (SRE) family. We present the complete genome sequence of Pcb strain BZA12, which reveals that Pcb strain BZA12 carries a single 4,924,809 bp chromosome with 51.97% GC content and comprises 4508 predicted protein-coding genes.Geneannotationofthese genes utilizedGO, KEGG,and COG databases.Incomparison withthree closely related soft-rot pathogens, strain BZA12 has 3797 gene families, among which 3107 gene families are identified as orthologous with those of both P. carotovorum subsp. carotovorum PCC21 and P. carotovorum subsp. odoriferum BCS7, as well as 36 putative Unique Gene Families. We selected five putative effectors from the BZA12 genome and transiently expressed them in Nicotiana benthamiana. Candidate effector A12GL002483 was localized in the cell nucleus and induced cell death. This study provides a foundation for a better understanding of the genomic structure and function of Pcb, particularly in the discovery of potential pathogenic factors and for the development of more effective strategies against this pathogen.


April 21, 2020

Physiological properties and genetic analysis related to exopolysaccharide (EPS) production in the fresh-water unicellular cyanobacterium Aphanothece sacrum (Suizenji Nori).

The clonal strains, phycoerythrin(PE)-rich- and PE-poor strains, of the unicellular, fresh water cyanobacterium Aphanothece sacrum (Suringar) Okada (Suizenji Nori, in Japanese) were isolated from traditional open-air aquafarms in Japan. A. sacrum appeared to be oligotrophic on the basis of its growth characteristics. The optimum temperature for growth was around 20°C. Maximum growth and biomass increase at 20°C was obtained under light intensities between 40 to 80 µmol m-2 s-1 (fluorescent lamps, 12 h light/12 h dark cycles) and between 40 to 120 µmol m-2 s-1 for PE-rich and PE-poor strains, respectively, of A. sacrum . Purified exopolysaccharide (EPS) of A. sacrum has a molecular weight of ca. 104 kDa with five major monosaccharides (glucose, xylose, rhamnose, galactose and mannose; =85 mol%). We also deciphered the whole genome sequence of the two strains of A. sacrum. The putative genes involved in the polymerization, chain length control, and export of EPS would contribute to understand the biosynthetic process of their extremely high molecular weight EPS. The putative genes encoding Wzx-Wzy-Wzz- and Wza-Wzb-Wzc were conserved in the A. sacrum strains FPU1 and FPU3. This result suggests that the Wzy-dependent pathway participates in the EPS production of A. sacrum.


April 21, 2020

Discovery of tandem and interspersed segmental duplications using high-throughput sequencing.

Several algorithms have been developed that use high-throughput sequencing technology to characterize structural variations (SVs). Most of the existing approaches focus on detecting relatively simple types of SVs such as insertions, deletions and short inversions. In fact, complex SVs are of crucial importance and several have been associated with genomic disorders. To better understand the contribution of complex SVs to human disease, we need new algorithms to accurately discover and genotype such variants. Additionally, due to similar sequencing signatures, inverted duplications or gene conversion events that include inverted segmental duplications are often characterized as simple inversions, likewise, duplications and gene conversions in direct orientation may be called as simple deletions. Therefore, there is still a need for accurate algorithms to fully characterize complex SVs and thus improve calling accuracy of more simple variants.We developed novel algorithms to accurately characterize tandem, direct and inverted interspersed segmental duplications using short read whole genome sequencing datasets. We integrated these methods to our TARDIS tool, which is now capable of detecting various types of SVs using multiple sequence signatures such as read pair, read depth and split read. We evaluated the prediction performance of our algorithms through several experiments using both simulated and real datasets. In the simulation experiments, using a 30× coverage TARDIS achieved 96% sensitivity with only 4% false discovery rate. For experiments that involve real data, we used two haploid genomes (CHM1 and CHM13) and one human genome (NA12878) from the Illumina Platinum Genomes set. Comparison of our results with orthogonal PacBio call sets from the same genomes revealed higher accuracy for TARDIS than state-of-the-art methods. Furthermore, we showed a surprisingly low false discovery rate of our approach for discovery of tandem, direct and inverted interspersed segmental duplications prediction on CHM1 (<5% for the top 50 predictions).TARDIS source code is available at https://github.com/BilkentCompGen/tardis, and a corresponding Docker image is available at https://hub.docker.com/r/alkanlab/tardis/.Supplementary data are available at Bioinformatics online. © The Author(s) 2019. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.


April 21, 2020

Long-Read Annotation: Automated Eukaryotic Genome Annotation Based on Long-Read cDNA Sequencing.

Single-molecule full-length complementary DNA (cDNA) sequencing can aid genome annotation by revealing transcript structure and alternative splice forms, yet current annotation pipelines do not incorporate such information. Here we present long-read annotation (LoReAn) software, an automated annotation pipeline utilizing short- and long-read cDNA sequencing, protein evidence, and ab initio prediction to generate accurate genome annotations. Based on annotations of two fungal genomes (Verticillium dahliae and Plicaturopsis crispa) and two plant genomes (Arabidopsis [Arabidopsis thaliana] and Oryza sativa), we show that LoReAn outperforms popular annotation pipelines by integrating single-molecule cDNA-sequencing data generated from either the Pacific Biosciences or MinION sequencing platforms, correctly predicting gene structure, and capturing genes missed by other annotation pipelines. © 2019 American Society of Plant Biologists. All Rights Reserved.


April 21, 2020

Novel trimethoprim resistance gene dfrA34 identified in Salmonella Heidelberg in the USA.

Trimethoprim/sulfamethoxazole is a synthetic antibiotic combination recommended for the treatment of complicated non-typhoidal Salmonella infections in humans. Resistance to trimethoprim/sulfamethoxazole is mediated by the acquisition of mobile genes, requiring both a dfr gene (trimethoprim resistance) and a sul gene (sulfamethoxazole resistance) for a clinical resistance phenotype (MIC =4/76?mg/L). In 2017, the CDC investigated a multistate outbreak caused by a Salmonella enterica serotype Heidelberg strain with trimethoprim/sulfamethoxazole resistance, in which sul genes but no known dfr genes were detected.To characterize and describe the molecular mechanism of trimethoprim resistance in a Salmonella Heidelberg outbreak isolate.Illumina sequencing data for one outbreak isolate revealed a 588?bp ORF encoding a putative dfr gene. This gene was cloned into Escherichia coli and resistance to trimethoprim was measured by broth dilution and Etest. Phylogenetic analysis of previously reported dfrA genes was performed using MEGA. Long-read sequencing was conducted to determine the context of the novel dfr gene.The novel dfr gene, named dfrA34, conferred trimethoprim resistance (MIC =32?mg/L) when cloned into E. coli. Based on predicted amino acid sequences, dfrA34 shares less than 50% identity with other known dfrA genes. The dfrA34 gene is located in a class 1 integron in a multiresistance region of an IncC plasmid, adjacent to a sul gene, thus conferring clinical trimethoprim/sulfamethoxazole resistance. Additionally, dfrA34 is associated with ISCR1, enabling easy transmission between other plasmids and bacterial strains.


April 21, 2020

Genome assembly and gene expression in the American black bear provides new insights into the renal response to hibernation.

The prevalence of chronic kidney disease (CKD) is rising worldwide and 10-15% of the global population currently suffers from CKD and its complications. Given the increasing prevalence of CKD there is an urgent need to find novel treatment options. The American black bear (Ursus americanus) copes with months of lowered kidney function and metabolism during hibernation without the devastating effects on metabolism and other consequences observed in humans. In a biomimetic approach to better understand kidney adaptations and physiology in hibernating black bears, we established a high-quality genome assembly. Subsequent RNA-Seq analysis of kidneys comparing gene expression profiles in black bears entering (late fall) and emerging (early spring) from hibernation identified 169 protein-coding genes that were differentially expressed. Of these, 101 genes were downregulated and 68 genes were upregulated after hibernation. Fold changes ranged from 1.8-fold downregulation (RTN4RL2) to 2.4-fold upregulation (CISH). Most notable was the upregulation of cytokine suppression genes (SOCS2, CISH, and SERPINC1) and the lack of increased expression of cytokines and genes involved in inflammation. The identification of these differences in gene expression in the black bear kidney may provide new insights in the prevention and treatment of CKD. © The Author(s) 2018. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.


April 21, 2020

Nodule bacteria from the cultured legume Phaseolus dumosus (belonging to the Phaseolus vulgaris cross-inoculation group) with common tropici phenotypic characteristics and symbiovar but distinctive phylogenomic position and chromid.

Phaseolus dumosus is an endemic species from mountain tops in Mexico that was found in traditional agriculture areas in Veracruz, Mexico. P. dumosus plants were identified by ITS sequences and their nodules were collected from agricultural fields or from trap plant experiments in the laboratory. Bacteria from P. dumosus nodules were identified as belonging to the phaseoli-etli-leguminosarum (PEL) or to the tropici group by 16S rRNA gene sequences. We obtained complete closed genomes from two P. dumosus isolates CCGE531 and CCGE532 that were phylogenetically placed within the tropici group but with a distinctive phylogenomic position and low average nucleotide identity (ANI). CCGE531 and CCGE532 had common phenotypic characteristics with tropici type B rhizobial symbionts. Genome synteny analysis and ANI showed that P. dumosus isolates had different chromids and our analysis suggests that chromids have independently evolved in different lineages of the Rhizobium genus. Finally, we considered that P. dumosus and Phaseolus vulgaris plants belong to the same cross-inoculation group since they have conserved symbiotic affinites for rhizobia.Copyright © 2018 Elsevier GmbH. All rights reserved.


April 21, 2020

Genome-Scale Sequence Disruption Following Biolistic Transformation in Rice and Maize.

Biolistic transformation delivers nucleic acids into plant cells by bombarding the cells with microprojectiles, which are micron-scale, typically gold particles. Despite the wide use of this technique, little is known about its effect on the cell’s genome. We biolistically transformed linear 48-kb phage lambda and two different circular plasmids into rice (Oryza sativa) and maize (Zea mays) and analyzed the results by whole genome sequencing and optical mapping. Although some transgenic events showed simple insertions, others showed extreme genome damage in the form of chromosome truncations, large deletions, partial trisomy, and evidence of chromothripsis and breakage-fusion bridge cycling. Several transgenic events contained megabase-scale arrays of introduced DNA mixed with genomic fragments assembled by nonhomologous or microhomology-mediated joining. Damaged regions of the genome, assayed by the presence of small fragments displaced elsewhere, were often repaired without a trace, presumably by homology-dependent repair (HDR). The results suggest a model whereby successful biolistic transformation relies on a combination of end joining to insert foreign DNA and HDR to repair collateral damage caused by the microprojectiles. The differing levels of genome damage observed among transgenic events may reflect the stage of the cell cycle and the availability of templates for HDR. © 2019 American Society of Plant Biologists. All rights reserved.


April 21, 2020

RADAR-seq: A RAre DAmage and Repair sequencing method for detecting DNA damage on a genome-wide scale.

RAre DAmage and Repair sequencing (RADAR-seq) is a highly adaptable sequencing method that enables the identification and detection of rare DNA damage events for a wide variety of DNA lesions at single-molecule resolution on a genome-wide scale. In RADAR-seq, DNA lesions are replaced with a patch of modified bases that can be directly detected by Pacific Biosciences Single Molecule Real-Time (SMRT) sequencing. RADAR-seq enables dynamic detection over a wide range of DNA damage frequencies, including low physiological levels. Furthermore, without the need for DNA amplification and enrichment steps, RADAR-seq provides sequencing coverage of damaged and undamaged DNA across an entire genome. Here, we use RADAR-seq to measure the frequency and map the location of ribonucleotides in wild-type and RNaseH2-deficient E. coli and Thermococcus kodakarensis strains. Additionally, by tracking ribonucleotides incorporated during in vivo lagging strand DNA synthesis, we determined the replication initiation point in E. coli, and its relation to the origin of replication (oriC). RADAR-seq was also used to map cyclobutane pyrimidine dimers (CPDs) in Escherichia coli (E. coli) genomic DNA exposed to UV-radiation. On a broader scale, RADAR-seq can be applied to understand formation and repair of DNA damage, the correlation between DNA damage and disease initiation and progression, and complex biological pathways, including DNA replication.Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.


April 21, 2020

Secretion of an Argonaute protein by a parasitic nematode and the evolution of its siRNA guides.

Extracellular RNA has been proposed to mediate communication between cells and organisms however relatively little is understood regarding how specific sequences are selected for export. Here, we describe a specific Argonaute protein (exWAGO) that is secreted in extracellular vesicles (EVs) released by the gastrointestinal nematode Heligmosomoides bakeri, at multiple copies per EV. Phylogenetic and gene expression analyses demonstrate exWAGO orthologues are highly conserved and abundantly expressed in related parasites but highly diverged in free-living genus Caenorhabditis. We show that the most abundant small RNAs released from the nematode parasite are not microRNAs as previously thought, but rather secondary small interfering RNAs (siRNAs) that are produced by RNA-dependent RNA Polymerases. The siRNAs that are released in EVs have distinct evolutionary properties compared to those resident in free-living or parasitic nematodes. Immunoprecipitation of exWAGO demonstrates that it specifically associates with siRNAs from transposons and newly evolved repetitive elements that are packaged in EVs and released into the host environment. Together this work demonstrates molecular and evolutionary selectivity in the small RNA sequences that are released in EVs into the host environment and identifies a novel Argonaute protein as the mediator of this. © The Author(s) 2019. Published by Oxford University Press on behalf of Nucleic Acids Research.


April 21, 2020

A 12-kb structural variation in progressive myoclonic epilepsy was newly identified by long-read whole-genome sequencing.

We report a family with progressive myoclonic epilepsy who underwent whole-exome sequencing but was negative for pathogenic variants. Similar clinical courses of a devastating neurodegenerative phenotype of two affected siblings were highly suggestive of a genetic etiology, which indicates that the survey of genetic variation by whole-exome sequencing was not comprehensive. To investigate the presence of a variant that remained unrecognized by standard genetic testing, PacBio long-read sequencing was performed. Structural variant (SV) detection using low-coverage (6×) whole-genome sequencing called 17,165 SVs (7,216 deletions and 9,949 insertions). Our SV selection narrowed down potential candidates to only five SVs (two deletions and three insertions) on the genes tagged with autosomal recessive phenotypes. Among them, a 12.4-kb deletion involving the CLN6 gene was the top candidate because its homozygous abnormalities cause neuronal ceroid lipofuscinosis. This deletion included the initiation codon and was found in a GC-rich region containing multiple repetitive elements. These results indicate the presence of a causal variant in a difficult-to-sequence region and suggest that such variants that remain enigmatic after the application of current whole-exome sequencing technology could be uncovered by unbiased application of long-read whole-genome sequencing.


April 21, 2020

Characterization of the genome of a Nocardia strain isolated from soils in the Qinghai-Tibetan Plateau that specifically degrades crude oil and of this biodegradation.

A strain of Nocardia isolated from crude oil-contaminated soils in the Qinghai-Tibetan Plateau degrades nearly all components of crude oil. This strain was identified as Nocardia soli Y48, and its growth conditions were determined. Complete genome sequencing showed that N. soli Y48 has a 7.3?Mb genome and many genes responsible for hydrocarbon degradation, biosurfactant synthesis, emulsification and other hydrocarbon degradation-related metabolisms. Analysis of the clusters of orthologous groups (COGs) and genomic islands (GIs) revealed that Y48 has undergone significant gene transfer events to adapt to changing environmental conditions (crude oil contamination). The structural features of the genome might provide a competitive edge for the survival of N. soli Y48 in oil-polluted environments and reflect the adaptation of coexisting bacteria to distinct nutritional niches.Copyright © 2018. Published by Elsevier Inc.


April 21, 2020

Fast and accurate genomic analyses using genome graphs.

The human reference genome serves as the foundation for genomics by providing a scaffold for alignment of sequencing reads, but currently only reflects a single consensus haplotype, thus impairing analysis accuracy. Here we present a graph reference genome implementation that enables read alignment across 2,800 diploid genomes encompassing 12.6 million SNPs and 4.0 million insertions and deletions (indels). The pipeline processes one whole-genome sequencing sample in 6.5?h using a system with 36?CPU cores. We show that using a graph genome reference improves read mapping sensitivity and produces a 0.5% increase in variant calling recall, with unaffected specificity. Structural variations incorporated into a graph genome can be genotyped accurately under a unified framework. Finally, we show that iterative augmentation of graph genomes yields incremental gains in variant calling accuracy. Our implementation is an important advance toward fulfilling the promise of graph genomes to radically enhance the scalability and accuracy of genomic analyses.


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