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Divergence between samples of chimpanzee and human DNA sequences is 5%, counting indels.

Five chimpanzee bacterial artificial chromosome (BAC) sequences (described in GenBank) have been compared with the best matching regions of the human genome sequence to assay the amount and kind of DNA divergence. The conclusion is the old saw that we share 98.5% of our DNA sequence with chimpanzee is probably in error. For this sample, a better estimate would be that 95% of the base pairs are exactly shared between chimpanzee and human DNA. In this sample of 779 kb, the divergence due to base substitution is 1.4%, and there is an additional 3.4% difference due to the presence of indels. The gaps in alignment are present in about equal amounts in the chimp and human sequences. They occur equally in repeated and nonrepeated sequences, as detected by REPEATMASKER (http://ftp.genome.washington.edu/RM/RepeatMasker.html).

Animals↗

Heterozygous indels as useful tools in the reconstruction of DNA sequences and in the assessment of ploidy level and genomic constitution of hybrid organisms.

In this paper we describe a simple approach using double peaks in chromatograms generated as artefacts in the vicinity of heterozygous indels, to identify the specific sequences present in individual strands of a given DNA fragment. This method is useful to assign bases in individuals that are heterozygous at multiple sites. In addition, the relative sizes of the double peaks help to determine the ploidy level and the relative contribution of the parental genomes in hybrids. Our interpretation was confirmed with the analysis of artificial mixtures of DNA of two different species. Results were robust with varying PCR and sequencing conditions. The applicability of this method was demonstrated in hybrids of the Squalius alburnoides complex and in heterozygotes of Chondrostoma oligolepis. Far from being limited to these fish models and the gene where it was tested (beta-actin), this sequence reconstruction methodology is expected to have a broader application.

Animals↗

Naturally occurring indel variation in the Brassica nigra COL1 gene is associated with variation in flowering time.

Previous QTL mapping identified a Brassica nigra homolog to Arabidopsis thaliana CO as a candidate gene affecting flowering time in B. nigra. Transformation of an A. thaliana co mutant with two different alleles of the B. nigra CO (Bni COa) homolog, one from an early-flowering B. nigra plant and one from a late one, did not show any differential effect of the two alleles on flowering time. The DNA sequence of the coding region of the two alleles was also identical, showing that nucleotide variation influencing flowering time must reside outside the coding region of Bni COa. In contrast, the nucleotide sequence of the B. nigra COL1 (Bni COL1) gene located 3.5 kb upstream of Bni COa was highly diverged between the alleles from early and late plants. One indel polymorphism in the Bni COL1 coding region, present in several natural populations of B. nigra, displayed a significant association with flowering time within a majority of these populations. These data indicate that a quantitative trait nucleotide (QTN) affecting flowering time is located within or close to the Bni COL1 gene. The intergenic sequence between Bni COL1 and Bni COa displayed a prominent peak of divergence 1 kb downstream of the Bni COL1 coding region. This region could contain regulatory elements for the downstream Bni COa gene. Our data suggest that a naturally occurring QTN for flowering time affects the function or expression of either Bni COL1 or Bni COa.

Base Sequence↗

Screening for dual sgRNAs with comparable indel efficiencies enhances CRISPR-mediated large-fragment deletion.

CRISPR-mediated large-fragment deletion provides a powerful approach for gene clusters, noncoding regions and structural variants, but its broader application is limited by low and variable deletion efficiency. Here, we systematically designed and evaluated 78 sgRNAs targeting nine representative gene clusters (ttn.1-ttn.2 cluster, 7 hox clusters and nppb-nppa cluster), containing 31 large fragments (5 kb-340 kb) to investigate the determinants of deletion efficiency. We found two key rules for achieving high deletion efficiency: (i) using dual sgRNAs with similar indel efficiencies, and (ii) applying a single sgRNA pair rather than multiple sgRNAs. Based on those rules, a 340 kb deletion is detected in the progenies of 95% of founders. Whereas the deletion size showed no significant linear correlation with deletion efficiency within the tested range. Implementing these rules resulted in an average of 70% of founders transmitting deletions across all tested sgRNA pairs. Therefore, screening sgRNAs can effectively enhance CRISPR utility in deletions, thereby facilitating the application of genomic manipulation in vertebrates and other species.

CRISPR↗

SNP2CAPS: a SNP and INDEL analysis tool for CAPS marker development.

With the influx of various SNP genotyping assays in recent years, there has been a need for an assay that is robust, yet cost effective, and could be performed using standard gel-based procedures. In this context, CAPS markers have been shown to meet these criteria. However, converting SNPs to CAPS markers can be a difficult process if done manually. In order to address this problem, we describe a computer program, SNP2CAPS, that facilitates the computational conversion of SNP markers into CAPS markers. 413 multiple aligned sequences derived from barley ESTs were analysed for the presence of polymorphisms in 235 distinct restriction sites. 282 (90%) of 314 alignments that contain sequence variation due to SNPs and InDels revealed at least one polymorphic restriction site. After reducing the number of restriction enzymes from 235 to 10, 31% of the polymorphic sites could still be detected. In order to demonstrate the usefulness of this tool for marker development, we experimentally validated some of the results predicted by SNP2CAPS.

Base Sequence↗

Unusual indelible enamel staining following fixed appliance treatment.

Two cases are described of indelible enamel staining following fixed appliance therapy. The acquired pigmentation occurred in patients with an identifiable enamel defect prior to treatment. The interaction of factors to cause the staining is discussed and it's prevention in future cases highlighted. Subsequent restoration of the affected teeth is shown.

Amelogenesis Imperfecta↗

Phylogenetic, amino acid content and indel analyses of the beta subunit of DNA-dependent RNA polymerase of gram-positive and gram-negative bacteria.

In this study, we have sequenced the rpoB gene, encoding the beta subunit of DNA-dependent RNA polymerase, from a selection of gram-positive and gram-negative bacteria. The presence of insertions and deletions (indels) in the beta subunit separate the gram-positive and gram-negative bacteria from each other and support the division of the gram-positive organisms into two clades based on DNA G+C content. Phylogenetic and amino acid content analyses further separate the clostridia from bacilli, leuconostocs, listeriae and relatives, forming an early branch after the common gram-positive ancestor. The occurrence in the beta subunit of Asn-Ala at positions 471-472 in Porphyromonas cangingivalis and Asn at position 372 in Weissella paramesenteroides are postulated to be the cause of the natural rifampicin resistance of these species.

Amino Acid Sequence↗

Conserved indels in protein sequences that are characteristic of the phylum Actinobacteria.

Gram-positive bacteria with a high G+C content are currently recognized as a distinct phylum, Actinobacteria, on the basis of their branching in 16S rRNA trees. Except for an insert in the 23S rRNA, there are no unique biochemical or molecular characteristics known at present that can distinguish this group from all other bacteria. In this work, three conserved indels (i.e. inserts or deletions) are described in three widely distributed proteins that are distinctive characteristics of the Actinobacteria and are not found in any other groups of bacteria. The identified signatures are a 2 aa deletion in cytochrome-c oxidase subunit 1 (Cox1), a 4 aa insert in CTP synthetase and a 5 aa insert in glutamyl-tRNA synthetase (GluRS). Additionally, the actinobacterial specificity of the large insert in the 23S rRNA was also tested. Using primers designed for conserved regions flanking these signatures, fragments of most of these genes were amplified from 23 actinobacterial species, covering many different families and orders, for which no sequence information was previously available. All the 61 sequenced fragments, except two in GluRS, were found to contain the indicated signatures. The presence of these signatures in various species from 20 families within this phylum provides evidence that they are likely distinctive characteristics of the entire phylum, which were introduced in a common ancestor of this group. The absence of all four of these signatures in Symbiobacterium thermophilum suggests that this species, which is distantly related to other actinobacteria in 16S rRNA and CTP synthetase trees, may not be a part of the phylum Actinobacteria. The identified signatures provide novel molecular means for defining and circumscribing the phylum Actinobacteria. Functional studies on them should prove helpful in understanding novel biochemical and physiological characteristics of this group of bacteria.

Actinobacteria↗

Conserved indels in essential proteins that are distinctive characteristics of Chlamydiales and provide novel means for their identification.

All known chlamydiae are either proven human or animal pathogens or possess such potential. Due to increasing reports of chlamydiae diversity in the environment, it is important to develop reliable means for identifying and characterizing Chlamydiales species. The identification of environmental chlamydiae at present relies on their branching pattern in 16S rRNA trees, as well as 16S/23S consensus motifs which display variability. At present, no reliable molecular signatures are known which are unique to all Chlamydiales species. Besides the rRNAs, sequence information for different Chlamydiales is not available for any other gene sequence. In this report, a number of molecular signatures are described that consist of conserved inserts and deletions (indels), in widely distributed proteins [RNA polymerase alpha subunit (RpoA), elongation factor (EF)-Tu, EF-P, DNA gyrase B subunit (GyrB) and lysyl-tRNA synthetase (LysRS)], that are distinctive characteristics of all available chlamydiae homologues (from Chlamydiaeceae species and Parachlamydiae sp. UWE25) and not found in any other bacteria. Using PCR primers for highly conserved regions in these proteins, the corresponding fragments of these genes from Simkania negevensis, Waddlia chondrophila, and in a number of cases for Neochlamydia hartmanellae, covering all families within the phylum Chlamydiae, have been cloned and sequenced. The shared presence of the identified signatures in these species provides strong evidence that these molecular signatures are distinctive characteristics of the entire order Chlamydiales and can be used to reliably determine the presence of chlamydiae or chlamydia-related organisms in environmental samples. The sequence information for these protein fragments was also used to determine the interrelationships among chlamydiae species. In a phylogenetic tree based on a combined dataset of sequences from RpoA, EF-Tu, EF-P and GyrB, the environmental chlamydiae (i.e. Simkania, Waddlia and Parachlamydia) and the traditional Chlamydiaceae (i.e. Chlamydophila and Chlamydia) formed two distinct clades. Similar relationships were also observed in individual protein phylogenies, as well as in a 16S rRNA tree for the same species. These results provide evidence that the divergence between the traditional Chlamydiaceae species and the other chlamydiae families occurred very early in the evolution of this group of bacteria.

Chlamydiales↗

Hereditary amyloidosis in early childhood associated with a novel insertion-deletion (indel) in the fibrinogen Aalpha chain gene.

BACKGROUND: Systemic amyloidosis occurring in early childhood is extremely rare, and is usually of AA type complicating chronic inflammatory diseases. We report the molecular basis of amyloidosis in a Korean girl who presented at 7 years of age with asymptomatic proteinuria and developed amyloid hepatomegaly and end-stage renal failure within 2 years. METHODS: Renal biopsy showed enlarged glomeruli virtually replaced by amyloid, but without interstitial or vascular involvement. The histologic appearance was identical to that seen in patients with hereditary fibrinogen Aalpha chain Glu526Val amyloidosis, and the amyloid deposits stained specifically with antibodies to fibrinogen. Mutations were sought in the genes of the amyloidogenic proteins, transthyretin, apolipoprotein AI, lysozyme and fibrinogen Aalpha chain genes by polymerase chain reaction (PCR) and sequencing. RESULTS: A unique frameshift insertion-deletion (indel) mutation was identified in one allele of her fibrinogen Aalpha chain gene, which encodes a partly novel peptide and a premature stop signal, similar to the two previously reported amyloidogenic point deletions at codons 522 and 524 in this molecule. The mutation was absent in samples verified to be from her parents, indicating that it had occurred de novo. CONCLUSION: This is the first description of hereditary fibrinogen Aalpha chain amyloidosis in an Asian individual, and the distinctive renal histology offered a strong clue to the diagnosis. The disease is potentially curable by combined hepatorenal transplantation.

Amino Acid Sequence↗

Variation in the 16S-23S rRNA intergenic spacer regions in Vibrio parahaemolyticus strains are due to indels nearby their tRNAGlu.

Vibrio parahaemolyticus contains 11 rRNA operons each including one of six 16S-23S rRNA gene intergenic spacer classes differing in size and nucleotide sequence. Some of the spacer classes may differ between isolates. We observed that the differences in the spacers between isolates are generally in two spacer classes present in single copies in the genome, one class containing tRNA(Ala) and tRNA(Glu) and the other tRNA(Glu) exclusively. Moreover, these differences are due to indels located nearby their tRNA(Glu). Comparison of the nucleotide sequence between spacer classes suggests that intragenomic nonreciprocal recombination causes the size variations observed in the spacer regions of V. parahaemolyticus strains.

Base Sequence↗

On the inference of parsimonious indel evolutionary scenarios.

Given a multiple alignment of orthologous DNA sequences and a phylogenetic tree for these sequences, we investigate the problem of reconstructing a most parsimonious scenario of insertions and deletions capable of explaining the gaps observed in the alignment. This problem, called the Indel Parsimony Problem, is a crucial component of the problem of ancestral genome reconstruction, and its solution provides valuable information to many genome functional annotation approaches. We first show that the problem is NP-complete. Second, we provide an algorithm, based on the fractional relaxation of an integer linear programming formulation. The algorithm is fast in practice, and the solutions it produces are, in most cases, provably optimal. We describe a divide-and-conquer approach that makes it possible to solve very large instances on a simple desktop machine, while retaining guaranteed optimality. Our algorithms are tested and shown efficient and accurate on a set of 1.8 Mb mammalian orthologous sequences in the CFTR region.

Algorithms↗

Evolutionary implications of matK indels in Poaceae.

Insertion/deletion events (indels) and nucleotide substitutions at the extreme 3' end of the chloroplast gene matK have been identified that distinguish certain major lineages of grasses. A 1-bp (base pair) deletion creating a shift in the open reading frame (ORF) and a point mutation support the positions of Streptochaeta and Anomochloa as the two most basal lineages in Poaceae. Another 1-bp deletion resulting in early termination of the ORF is unique to Ehrharta, a member of the taxonomically disputable tribe Ehrharteae. A 6-bp insertion supports monophyly of subfamilies Panicoideae, Arundinoideae, Centothecoideae, and Chloridoideae (PACC). This marker appears useful in defining PACC clade members and may have potential in providing insight into the sister-group relationship between PACC and other lineages. Alignment of deduced amino acid sequences from bryophytes, gymnosperms, and angiosperms shows that this region is relatively conserved, but variation is notably higher in Poaceae. The evolutionary implications of these changes in grasses and other plant families are addressed.

Journal Article↗

TriosCompass: a snakemake workflow for integrated detection of SNVs, indels, STRs, and structural de novo variants in parent-child trios.

MOTIVATION: The accurate and sensitive identification of de novo variants, which are unique to an individual and not found in the parents' germlines, is critical for understanding the genetic basis of rare diseases, developmental disorders, and evolutionary processes. Existing de novo variant detection pipelines often lack the flexibility to handle multiple variant types, struggle with speed and reproducibility across computational environments, demand extensive manual configuration, or require bioinformatics expertise for downstream curation and analysis, limiting their scalability and usability for large genomic studies. Accordingly, there is a pressing need to better address these challenges. RESULTS: We introduce TriosCompass, an open-source Snakemake workflow that addresses these challenges by providing a modular, accelerated, and environmentally-configurable end-to-end solution for comprehensive de novo variant discovery. It integrates state-of-the-art tools into a reproducible framework, empowering researchers to discover novel genetic insights with greater efficiency and reliability. AVAILABILITY: TriosCompass is implemented as a Snakemake workflow and is freely available at https://github.com/NCI-CGR/TriosCompass_v2 or on Zenodo (10.5281/zenodo.17981062). SUPPLEMENTARY INFORMATION: Supplementary data is available on GitHub at https://github.com/NCI-CGR/TriosCompass_v2/tree/manuscript/report_dashboards. Supplementary methods on DeepTrio benchmark runs can be viewed at: https://github.com/NCI-CGR/TriosCompass_v2/blob/manuscript/TriosCompass_Supp_Methods_deeptrio_benchmark.md.

Software↗