Since its first release in 2001 as mainly a software package for phylogenetic analysis, data analysis for molecular biology and evolution (DAMBE) has gained many new functions that may be classified into six categories: 1) sequence retrieval, editing, manipulation, and conversion among more than 20 standard sequence formats including MEGA, NEXUS, PHYLIP, GenBank, and the new NeXML format for interoperability, 2) motif characterization and discovery functions such as position weight matrix and Gibbs sampler, 3) descriptive genomic analysis tools with improved versions of codon adaptation index, effective number of codons, protein isoelectric point profiling, RNA and protein secondary structure prediction and calculation of minimum folding energy, and genomic skew plots with optimized window size, 4) molecular phylogenetics including sequence alignment, testing substitution saturation, distance-based, maximum parsimony, and maximum-likelihood methods for tree reconstructions, testing the molecular clock hypothesis with either a phylogeny or with relative-rate tests, dating gene duplication and speciation events, choosing the best-fit substitution models, and estimating rate heterogeneity over sites, 5) phylogeny-based comparative methods for continuous and discrete variables, and 6) graphic functions including secondary structure display, optimized skew plot, hydrophobicity plot, and many other plots of amino acid properties along a protein sequence, tree display and drawing by dragging nodes to each other, and visual searching of the maximum parsimony tree. DAMBE features a graphic, user-friendly, and intuitive interface and is freely available from http://dambe.bio.uottawa.ca (last accessed April 16, 2013).

https://www.ruor.uottawa.ca/bitstream/10393/31435/1/Mol%20Biol%20Evol-2013-Xia-1720-8.pdf

DAMBE5: a comprehensive software package for data analysis in molecular biology and evolution

Bacillus thuringiensis bacteria are insect pathogens that produce different Cry and Cyt toxins to kill their hosts. Here we review the group of three-domain Cry (3d-Cry) toxins. Expression of these 3d-Cry toxins in transgenic crops has contributed to efficient control of insect pests and a reduction in the use of chemical insecticides. The mode of action of 3d-Cry toxins involves sequential interactions with several insect midgut proteins that facilitate the formation of an oligomeric structure and induce its insertion into the membrane, forming a pore that kills midgut cells. We review recent progress in our understanding of the mechanism of action of these Cry toxins and focus our attention on the different mechanisms of resistance that insects have evolved to counter their action, such as mutations in cadherin, APN and ABC transporter genes. Activity of Cry1AMod toxins, which are able to form toxin oligomers in the absence of receptors, against different resistant populations, including those affected in the ABC transporter and the role of dominant negative mutants as antitoxins, supports the hypothesis that toxin oligomerization is a limiting step in the Cry insecticidal activity. Knowledge of the action of 3d-Cry toxin and the resistance mechanisms to these toxins will set the basis for a rational design of novel toxins to overcome insect resistance, extending the useful lifespan of Cry toxins in insect control programs.

Bacillus thuringiensis insecticidal three‐domain Cry toxins: mode of action, insect resistance and consequences for crop protection

https://pure.uva.nl/ws/files/2347122/161040_ABC_transporters_in_Arthropods.pdf

The ABC gene family in arthropods: Comparative genomics and role in insecticide transport and resistance

Arthropods were the first animalsto conquer land and air. They encompass more than three quarters of all described living species.Thisextraordinaryevolutionarysuccessisbasedonanastoundinglywidearrayofhighly adaptivebody organizations. A lackofrobustlyresolvedphylogeneticrelationships,however,currentlyimpedesthereliablereconstructionoftheunderlyingevolutionaryprocesses.Here,weshowthatphylogenomicdatacansubstantiallyadvanceourunderstandingofarthropod evolution and resolve several conflicts among existinghypotheses. We assembled a data set of 233 taxa and 775 genes from which an optimally informative data set of 117 taxa and 129 genes was finally selected using new heuristics and compared with the unreduced data set.We included novelexpressed sequencetag (EST) data for 11 species and allpublished phylogenomic data augmentedbyrecentlypublishedESTdata ontaxonomicallyimportantarthropodtaxa.This thorough sampling reduces the chance of obtainingspurious results due to stochastic effects of undersampling taxa and genes. Orthology prediction of genes, alignmentmasking tools, and selection of most informativegenes due to a balanced taxa–gene ratio using new heuristics were established.Our optimizeddata setrobustly resolves major arthropod relationships.We received strong supportforasistergrouprelationshipofonychophoransandeuarthropodsandstrongsupportforacloseassociationoftardigrades andcycloneuralia.Withinpancrustaceans,our analysesyieldedparaphyleticcrustaceansandmonophyletichexapods and robustly resolved monophyletic endopterygoteinsects.However, our analysesalsoshowed for few deep splitsthat were recently thought to be resolved,for example,the positionofmyriapods, a remarkable sensitivitytomethods of analyses.

/pdf/a-phylogenomic-approach-to-resolve-the-arthropod-tree-of-3nxzrze8l6.pdf

A Phylogenomic Approach to Resolve the Arthropod Tree of Life

Further use of nearly complete 28S and 18S rRNA genes to classify Ecdysozoa: 37 more arthropods and a kinorhynch.

The ATP-binding cassette (ABC) transporter superfamily is the largest transporter gene family responsible for transporting specific molecules across lipid membranes in all living organisms. In insects, ABC transporters not only have important functions in molecule transport, but also play roles in insecticide resistance, metabolism and development. From the genome of the silkworm, Bombyx mori, we have identified 51 putative ABC genes which are classified into eight subfamilies (A-H) by phylogenetic analysis. Gene duplication is very evident in the ABCC and ABCG subfamilies, whereas gene numbers and structures are well conserved in the ABCD, ABCE, ABCF, and ABCH subfamilies. Microarray analysis revealed that expression of 32 silkworm ABC genes can be detected in at least one tissue during different developmental stages, and the expression patterns of some of them were confirmed by quantitative real-time PCR. A large number of ABC genes were highly expressed in the testis compared to other tissues. One of the ABCG genes, BmABC002712, was exclusively and abundantly expressed in the Malpighian tubule implying that BmABC002712 plays a tissue-specific role. At least 5 ABCG genes, including BmABC005226, BmABC005203, BmABC005202, BmABC010555, and BmABC010557, were preferentially expressed in the midgut, showing similar developmental expression profiles to those of 20-hydroxyecdysone (20E)-response genes. 20E treatment induced the expression of these ABCG genes in the midgut and RNA interference-mediated knockdown of USP, a component of the 20E receptor, decreased their expression, indicating that these midgut-specific ABCG genes are 20E-responsive. In this study, a genome-wide analysis of the silkworm ABC transporters has been conducted. A comparison of ABC transporters from 5 insect species provides an overview of this vital gene superfamily in insects. Moreover, tissue- and stage-specific expression data of the silkworm ABCG genes lay a foundation for future analysis of their physiological function and hormonal regulation.

/pdf/genome-wide-identification-and-characterization-of-atp-5f4bucq5m0.pdf

Genome-wide identification and characterization of ATP-binding cassette transporters in the silkworm, Bombyx mori

This study combined complete 18S with partial 28S ribosomal RNA gene sequences ( approximately 2,000 nt in total) to investigate the relations of basal hexapods. Ten species of Protura, 12 of Diplura, and 10 of Collembola (representing all subgroups of these three clades) were sequenced, along with 5 true insects and 8 other arthropods, which served as out-groups. Trees were constructed with maximum parsimony, maximum likelihood, Bayesian analysis, and minimum-evolution analysis of LogDet-transformed distances. All methods yielded strong support for a clade of Protura plus Diplura, here named Nonoculata, and for monophyly of the Diplura. Parametric-bootstrapping analysis showed our data to be inconsistent with previous hypotheses (P 2,100 nt) showed monophyly of Campodeoidea and of Japygoidea, and most methods united Projapygoidea with Japygoidea.

The Phylogenetic Positions of Three Basal-Hexapod Groups (Protura, Diplura, and Collembola) Based on Ribosomal RNA Gene Sequences

Molecular phylogeny of Collembola inferred from ribosomal RNA genes

This study combined nearly complete 28S and 18S rRNA gene sequences (>4100 nt long) to investigate the phylogenetic relationships of basal hexapods (Protura, Collembola, and Diplura). It sequenced more 28S genes, to expand on a previous study from this lab that used 18S plus only a tiny part of the 28S gene. Sixteen species of basal hexapods, five insects, six crustaceans, two myriapods, and two chelicerates were included in the analyses. Trees were constructed with maximum likelihood, Bayesian analysis, and minimum-evolution analysis of LogDet-transformed distances. All methods yielded consistent results: (1) Hexapoda was monophyletic and nested in a paraphyletic Crustacea, and Hexapoda was divided into Entognatha [Collembola+Nonoculata (Protura plus Diplura)] and Insecta (=Ectognatha), but the Nonoculata clade must be accepted with caution because of its strong nonstationarity of nucleotide composition. (2) Within Diplura, the monophyly of Campodeoidea and of Japygoidea were supported respectively, and all methods united Projapygoidea with Japygoidea. (3) Within Protura, Sinentomidae was the sister group to Acerentomata. (4) Within Collembola, the modern taxonomical hierarchy of Collembola (Poduromorpha, Entomobryomorpha, Symphypleona and Neelipleona) was confirmed.

/pdf/phylogenetic-relationships-of-basal-hexapods-reconstructed-5p3kn7nelq.pdf

Phylogenetic Relationships of Basal Hexapods Reconstructed from Nearly Complete 18S and 28S rRNA Gene Sequences

The phylogenetic position of the Protura, traditionally considered the most basal hexapod group, is disputed because it has many unique morphological characters compared with other hexapods. Although mitochondrial genome information has been used extensively in phylogenetic studies, such information is not available for the Protura. This has impeded phylogenetic studies on this taxon, as well as the evolution of the arthropod mitochondrial genome. In this study, the mitochondrial genome of Sinentomon erythranum was sequenced, as the first proturan species to be reported. The genome contains a number of special features that differ from those of other hexapods and arthropods. As a very small arthropod mitochondrial genome, its 14,491 nucleotides encode 37 typical mitochondrial genes. Compared with other metazoan mtDNA, it has the most biased nucleotide composition with T = 52.4%, an extreme and reversed AT-skew of -0.351 and a GC-skew of 0.350. Two tandemly repeated regions occur in the A+T-rich region, and both could form stable stem-loop structures. Eighteen of the 22 tRNAs are greatly reduced in size with truncated secondary structures. The gene order is novel among available arthropod mitochondrial genomes. Rearrangements have involved in not only small tRNA genes, but also PCGs (protein-coding genes) and ribosome RNA genes. A large block of genes has experienced inversion and another nearby block has been reshuffled, which can be explained by the tandem duplication and random loss model. The most remarkable finding is that trnL2(UUR) is not located between cox1 and cox2 as observed in most hexapod and crustacean groups, but is between rrnL and nad1 as in the ancestral arthropod ground pattern. The "cox1-cox2" pattern was further confirmed in three more representative proturan species. The phylogenetic analyses based on the amino acid sequences of 13 mitochondrial PCGs suggest S. erythranum failed to group with other hexapod groups. The mitochondrial genome of S. erythranum shows many different features from other hexapod and arthropod mitochondrial genomes. It underwent highly divergent evolution. The "cox1-cox2" pattern probably represents the ancestral state for all proturan mitogenomes, and suggests a long evolutionary history for the Protura.

/pdf/the-mitochondrial-genome-of-sinentomon-erythranum-arthropoda-hd0axyjw6u.pdf

Yun-Xia Luan

Papers

Genome-wide identification and characterization of ATP-binding cassette transporters in the silkworm, Bombyx mori

The Phylogenetic Positions of Three Basal-Hexapod Groups (Protura, Diplura, and Collembola) Based on Ribosomal RNA Gene Sequences

Molecular phylogeny of Collembola inferred from ribosomal RNA genes

Phylogenetic Relationships of Basal Hexapods Reconstructed from Nearly Complete 18S and 28S rRNA Gene Sequences

The mitochondrial genome of Sinentomon erythranum (Arthropoda: Hexapoda: Protura): an example of highly divergent evolution