Phylogeny and mitochondrial gene order variation in Lophotrochozoa in the light of new mitogenomic data from Nemertea

<p>Abstract</p> <p>Background</p> <p>The new animal phylogeny established several taxa which were not identified by morphological analyses, most prominently the Ecdysozoa (arthropods, roundworms, priapulids and others) and Lophotrochozoa (molluscs, annelids, brachiopods and others). Lophotrochozoan interrelationships are under discussion, e.g. regarding the position of Nemertea (ribbon worms), which were discussed to be sister group to e.g. Mollusca, Brachiozoa or Platyhelminthes. Mitochondrial genomes contributed well with sequence data and gene order characters to the deep metazoan phylogeny debate.</p> <p>Results</p> <p>In this study we present the first complete mitochondrial genome record for a member of the Nemertea, <it>Lineus viridis</it>. Except two <it>trnP </it>and <it>trnT</it>, all genes are located on the same strand. While gene order is most similar to that of the brachiopod <it>Terebratulina retusa</it>, sequence based analyses of mitochondrial genes place nemerteans close to molluscs, phoronids and entoprocts without clear preference for one of these taxa as sister group.</p> <p>Conclusion</p> <p>Almost all recent analyses with large datasets show good support for a taxon comprising Annelida, Mollusca, Brachiopoda, Phoronida and Nemertea. But the relationships among these taxa vary between different studies. The analysis of gene order differences gives evidence for a multiple independent occurrence of a large inversion in the mitochondrial genome of Lophotrochozoa and a re-inversion of the same part in gastropods. We hypothesize that some regions of the genome have a higher chance for intramolecular recombination than others and gene order data have to be analysed carefully to detect convergent rearrangement events.</p

Mitochondrial genome deletions and minicircles are common in lice (Insecta: Phthiraptera)

Background The gene composition, gene order and structure of the mitochondrial genome are remarkably stable across bilaterian animals. Lice (Insecta: Phthiraptera) are a major exception to this genomic stability in that the canonical single chromosome with 37 genes found in almost all other bilaterians has been lost in multiple lineages in favour of multiple, minicircular chromosomes with less than 37 genes on each chromosome. Results Minicircular mt genomes are found in six of the ten louse species examined to date and three types of minicircles were identified: heteroplasmic minicircles which coexist with full sized mt genomes (type 1); multigene chromosomes with short, simple control regions, we infer that the genome consists of several such chromosomes (type 2); and multiple, single to three gene chromosomes with large, complex control regions (type 3). Mapping minicircle types onto a phylogenetic tree of lice fails to show a pattern of their occurrence consistent with an evolutionary series of minicircle types. Analysis of the nuclear-encoded, mitochondrially-targetted genes inferred from the body louse, Pediculus, suggests that the loss of mitochondrial single-stranded binding protein (mtSSB) may be responsible for the presence of minicircles in at least species with the most derived type 3 minicircles (Pediculus, Damalinia). Conclusions Minicircular mt genomes are common in lice and appear to have arisen multiple times within the group. Life history adaptive explanations which attribute minicircular mt genomes in lice to the adoption of blood-feeding in the Anoplura are not supported by this expanded data set as minicircles are found in multiple non-blood feeding louse groups but are not found in the blood-feeding genus Heterodoxus. In contrast, a mechanist explanation based on the loss of mtSSB suggests that minicircles may be selectively favoured due to the incapacity of the mt replisome to synthesize long replicative products without mtSSB and thus the loss of this gene lead to the formation of minicircles in lice

Arthropod Phylogenetics in Light of Three Novel Millipede (Myriapoda: Diplopoda) Mitochondrial Genomes with Comments on the Appropriateness of Mitochondrial Genome Sequence Data for Inferring Deep Level Relationships

Background Arthropods are the most diverse group of eukaryotic organisms, but their phylogenetic relationships are poorly understood. Herein, we describe three mitochondrial genomes representing orders of millipedes for which complete genomes had not been characterized. Newly sequenced genomes are combined with existing data to characterize the protein coding regions of myriapods and to attempt to reconstruct the evolutionary relationships within the Myriapoda and Arthropoda. Results The newly sequenced genomes are similar to previously characterized millipede sequences in terms of synteny and length. Unique translocations occurred within the newly sequenced taxa, including one half of the Appalachioria falcifera genome, which is inverted with respect to other millipede genomes. Across myriapods, amino acid conservation levels are highly dependent on the gene region. Additionally, individual loci varied in the level of amino acid conservation. Overall, most gene regions showed low levels of conservation at many sites. Attempts to reconstruct the evolutionary relationships suffered from questionable relationships and low support values. Analyses of phylogenetic informativeness show the lack of signal deep in the trees (i.e., genes evolve too quickly). As a result, the myriapod tree resembles previously published results but lacks convincing support, and, within the arthropod tree, well established groups were recovered as polyphyletic. Conclusions The novel genome sequences described herein provide useful genomic information concerning millipede groups that had not been investigated. Taken together with existing sequences, the variety of compositions and evolution of myriapod mitochondrial genomes are shown to be more complex than previously thought. Unfortunately, the use of mitochondrial protein-coding regions in deep arthropod phylogenetics appears problematic, a result consistent with previously published studies. Lack of phylogenetic signal renders the resulting tree topologies as suspect. As such, these data are likely inappropriate for investigating such ancient relationships

Plow

Patent for a technologically improved combination plow and cultivator which includes a "combined winged plow and cultivator with a specially constructed beam to ensure stability, and hold the plow and the wings in proper contact with the earth (lines 13-16)

Syntheses of high valent fac-[99mTcO3]+ complexes and [2+3] cycloadditions with alkenes in water as a direct labelling strategy

Reported herein is a new concept for the labelling of biomolecules with small [(99m)TcO(3)](+) complexes through a [3+2] cycloaddition with alkenes for radiopharmaceutical applications. We developed convenient reactions for the synthesis of small, water stable fac-[TcO(3)(tacn-R)](+) complexes ((99)Tc and (99m)Tc, tacn = 1,4,7-triazacyclononane, R = H, -CH(2)-C(6)H(5), -CH(2)-C(6)H(4)COOH). With alkenes, these high valent [(99m)TcO(3)](+) complexes undergo [3+2] cycloaddition with formation of the corresponding Tc(V)-glycolato complexes. The (99m)Tc(V) and (99m)Tc(VII) complexes are stable at 37 degrees C in water and in the presence of serum proteins. Therefore, new opportunities in technetium chemistry are enabled with a high potential for medicinal and biological applications. In contrast to classical labelling, the presented strategy is ligand and not metal-centred

N-Benzylisatin

In the title compound, C15H11NO2, two C&amp;#8212;H...O hydrogen bonds are observed in the crystal structure, as well as &amp;#960;&amp;#8211;&amp;#960; stacking with a centroid&amp;#8211;centroid distance of 3.623&amp;#8197;(2)&amp;#8197;&amp;#197;. The planarity of the two ring systems is illustrated by very small deviations of all the atoms from these planes [largest deviations = 0.003&amp;#8197;(3) and 0.010&amp;#8197;(3)&amp;#8197;&amp;#197; for the phenyl and fused-benzene rings, respectively]. The dihedral angle between these two planes is 77.65&amp;#8197;(9)&amp;#176;