Giant tortoises are amongst the longest-lived vertebrate animals and as
such provide an excellent model to study traits like longevity and age-related
diseases. However, genomic and molecular evolutionary information on giant
tortoises is scarce. Here, we describe a global analysis of the genomes of
Lonesome George, the iconic last member of
Chelonoidis
abingdonii
, and the Aldabra giant tortoise (
Aldabrachelys
gigantea
). The comparison of these genomes to those of related
species, using both unsupervised and supervised analyses, led us to detect
lineage-specific variants affecting DNA repair genes, inflammatory mediators and
genes related to cancer development. Our study also hints at specific
evolutionary strategies linked to increased lifespan and expands our
understanding of the genomic determinants of ageing. These new genome sequences
also provide important resources to help the efforts for restoration of giant
tortoise populations.
Amplicon-based targeted next-generation sequencing assays are used widely to test for clinically relevant somatic mutations in cancer. However, accurate detection of large insertions and deletions (indels) via these assays remains challenging. Sequencing reads that cover these anomalies are, by definition, different from the reference sequence, and lead to variable performance of alignment algorithms. Reads with large indels may be aligned incorrectly, causing incorrect calls, or may remain unmapped and essentially ignored by downstream informatics pipeline sub-processes. Herein, we describe Amplicon Indel Hunter (AIH), a novel large (>5-bp) indel detection method that is reference genome independent and highly sensitive for the identification of somatic indels in amplicon-based, paired-end, next-generation sequencing data. We validated the algorithm for sensitivity and specificity using a set of clinical cancer samples with Clinical Laboratory Improvement Amendment-confirmed indels as well as in silico mutated data sets. The AIH detected 100% of tested large indels with relatively higher mutant allele frequencies compared with a variety of traditional aligners, which showed variably reduced sensitivity and specificity by comparison. The AIH especially outperformed alignment-based methods for detection of all tested FLT3 internal tandem duplications up to 102 bp. Because AIH runs in parallel to traditional alignment-based informatics pathways, it can be readily incorporated into nearly any analysis pipeline for somatic mutation detection in paired-end amplicon-based data.
"Candidatus Portiera aleyrodidarum" is the primary endosymbiont of whiteflies. We report two complete genome sequences of this bacterium from the worldwide invasive B and Q biotypes of the whitefly Bemisia tabaci. Differences in the two genome sequences may add insights into the complex differences in the biology of both biotypes.
ABSTRACT“CandidatusPortiera aleyrodidarum” is the obligate primary endosymbiotic bacterium of whiteflies, including the sweet potato whiteflyBemisia tabaci, and provides essential nutrients to its host. Here we report two complete genome sequences of this bacterium from the B and Q biotypes ofB. tabaci.
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