Galactic Phylogenetics

Phylogenetics is a widely used concept in evolutionary biology. It is the reconstruction of evolutionary history by building trees that represent branching patterns and sequences. These trees represent shared history, and it is our intention for this approach to be employed in the analysis of Galactic history. In Galactic archaeology the shared environment is the interstellar medium in which stars form and provides the basis for tree-building as a methodological tool. Using elemental abundances of solar-type stars as a proxy for DNA, we built in Jofre et al 2017 such an evolutionary tree to study the chemical evolution of the solar neighbourhood. In this proceeding we summarise these results and discuss future prospects.Comment: Contribution to IAU Symposium No. 334: Rediscovering our Galax

Molecular Characterization and Differential Expression of an Olfactory Receptor Gene Family in the White-Backed Planthopper <i>Sogatella furcifera</i> Based on Transcriptome Analysis

<div><p>The white-backed planthopper, <i>Sogatella furcifera</i>, a notorious rice pest in Asia, employs host plant volatiles as cues for host location. In insects, odor detection is mediated by two types of olfactory receptors: odorant receptors (ORs) and ionotropic receptors (IRs). In this study, we identified 63 <i>SfurORs</i> and 14 <i>SfurIRs</i> in <i>S</i>. <i>furcifera</i> based on sequences obtained from the head transcriptome and bioinformatics analysis. The motif-pattern of 130 hemiptera ORs indicated an apparent differentiation in this order. Phylogenetic trees of the ORs and IRs were constructed using neighbor-joining estimates. Most of the ORs had orthologous genes, but a specific OR clade was identified in <i>S</i>. <i>furcifera</i>, which suggests that these ORs may have specific olfactory functions in this species. Our results provide a basis for further investigations of how <i>S</i>. <i>furcifera</i> coordinates its olfactory receptor genes with its plant hosts, thereby providing a foundation for novel pest management approaches based on these genes.</p></div

Motif analysis of ORs in the Hemipera.

<p>Parameters used for motif discovery were: minimum width = 6, maximum width = 10, maximum number of motif to find = 8. The upper parts listed the eight motifs discovered in the 130 ORs using MEME (version 4.9.1) on line server (<a href="http://meme.nbcr.net/meme/" target="_blank">http://meme.nbcr.net/meme/</a>). The lower parts of different colors indicate approximate locations of each motif on the predicted protein sequence. The numbers in the boxes correspond to the numbered motifs in the upper part of the figure, where small number indicates high conservation. The numbers on the bottom showed the approximate locations of each motif on the protein sequence, starting from the N-terminal.</p

Distribution of transcripts and unigene length in the <i>S</i>. <i>furcifera</i> transcriptome assembly.

<p>Distribution of transcripts and unigene length in the <i>S</i>. <i>furcifera</i> transcriptome assembly.</p

Unigenes of candidate odorant receptors.

<p>Unigenes of candidate odorant receptors.</p

Phylogenetic tree of <i>S</i>. <i>furcifera</i> SfurORs and other hemipteran ORs.

<p>Species abbreviations: Ap, <i>A</i>. <i>pisum</i>; Ago, <i>A</i>. <i>gossypii</i>; Rpro, <i>R</i>. <i>prolixus</i>; Sfur, <i>S</i>. <i>furcifera</i>; Llin, <i>Lygus lineolaris</i>; Alum, <i>Apolygus lucorum</i>; Save, <i>Sitobion avenae</i>.</p

Unigenes of candidate ionotropic receptors.

<p>Unigenes of candidate ionotropic receptors.</p

Comparison of ORs (A) and IRs (B) in the head according to Illumina read mapping.

<p>The asterisk indicates very low values. FPKM, expected number of fragments per kilobase of transcript sequence per million base pairs sequenced.</p

Phylogenetic tree of putative <i>S</i>. <i>furcifera</i> IRs, <i>Drosophila melanogaster</i> iGluRs and IRs, and other insect IRs.

<p>SfurIRs are highlighted in red letters. Bmor, <i>Bombyx mori</i>; Cpom, <i>Cydia pomonella</i>; Dmel, <i>D</i>. <i>melanogaster</i>; Dple, <i>Danaus plexippus</i>; Harm, <i>Helicoverpa armigera</i>; Msex, <i>Manduca sexta</i>; Slit, <i>Spodoptera littoralis</i>; Snon, <i>Sesamia nonagrioides</i>; Ago, <i>A</i>. <i>gossypii</i>.</p

Mesophase Separation and Rheology of Olefin Multiblock Copolymers

Chain shuttling polymerization enables an efficient production of ethylene–octene block copolymers (OBCs) that combine different mechanical properties in a polymer chain. However, this method results in molecular weight polydispersity and multiblock chain structure. The melt-phase behavior and mesophase transition of the polydisperse OBCs with low octene content but different molecular weight and block composition were investigated by rheology, differential scanning calorimetry (DSC), atomic force microscopic (AFM), polarized optical microscopy (POM), and small-angle X-ray scattering (SAXS). Three rheological methods, namely the deviation of the scaling dependence of zero shear viscosity on molecular weight, the terminal behavior and the failure of time–temperature superposition (TTS), and two-dimensional rheological correlation spectrum, are used to reveal the mesophase separation with increasing sensitivity. The occurrence of mesophase separation transitions (MST) was observed in such low octene content and low molecular weight OBC systems, with much lower degree of segregation than the theoretical predictions in diblock copolymers. The extent of mesophase separation is further justified by its effect on subsequent crystallization behaviors