A Molecular Phylogeny of the Chalcidoidea (Hymenoptera)

Chalcidoidea (Hymenoptera) are extremely diverse with more than 23,000 species described and over 500,000 species estimated to exist. This is the first comprehensive phylogenetic analysis of the superfamily based on a molecular analysis of 18S and 28S ribosomal gene regions for 19 families, 72 subfamilies, 343 genera and 649 species. The 56 outgroups are comprised of Ceraphronoidea and most proctotrupomorph families, including Mymarommatidae. Data alignment and the impact of ambiguous regions are explored using a secondary structure analysis and automated (MAFFT) alignments of the core and pairing regions and regions of ambiguous alignment. Both likelihood and parsimony approaches are used to analyze the data. Overall there is no impact of alignment method, and few but substantial differences between likelihood and parsimony approaches. Monophyly of Chalcidoidea and a sister group relationship between Mymaridae and the remaining Chalcidoidea is strongly supported in all analyses. Either Mymarommatoidea or Diaprioidea are the sister group of Chalcidoidea depending on the analysis. Likelihood analyses place Rotoitidae as the sister group of the remaining Chalcidoidea after Mymaridae, whereas parsimony nests them within Chalcidoidea. Some traditional family groups are supported as monophyletic (Agaonidae, Eucharitidae, Encyrtidae, Eulophidae, Leucospidae, Mymaridae, Ormyridae, Signiphoridae, Tanaostigmatidae and Trichogrammatidae). Several other families are paraphyletic (Perilampidae) or polyphyletic (Aphelinidae, Chalcididae, Eupelmidae, Eurytomidae, Pteromalidae, Tetracampidae and Torymidae). Evolutionary scenarios discussed for Chalcidoidea include the evolution of phytophagy, egg parasitism, sternorrhynchan parasitism, hypermetamorphic development and heteronomy

Overexpressing 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) in the lactococcal mevalonate pathway for heterologous plant sesquiterpene production.

Isoprenoids are a large and diverse group of metabolites with interesting properties such as flavour, fragrance and therapeutic properties. They are produced via two pathways, the mevalonate pathway or the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway. While plants are the richest source of isoprenoids, they are not the most efficient producers. Escherichia coli and yeasts have been extensively studied as heterologous hosts for plant isoprenoids production. In the current study, we describe the usage of the food grade Lactococcus lactis as a potential heterologous host for the production of sesquiterpenes from a local herbaceous Malaysian plant, Persicaria minor (synonym Polygonum minus). A sesquiterpene synthase gene from P. minor was successfully cloned and expressed in L. lactis. The expressed protein was identified to be a β-sesquiphellandrene synthase as it was demonstrated to be functional in producing β-sesquiphellandrene at 85.4% of the total sesquiterpenes produced based on in vitro enzymatic assays. The recombinant L. lactis strain developed in this study was also capable of producing β-sesquiphellandrene in vivo without exogenous substrates supplementation. In addition, overexpression of the strain's endogenous 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGR), an established rate-limiting enzyme in the eukaryotic mevalonate pathway, increased the production level of β-sesquiphellandrene by 1.25-1.60 fold. The highest amount achieved was 33 nM at 2 h post-induction

Sesquiterpenes produced by the recombinant PMSTS protein in <i>in vitro</i> enzymatic assay as detected by GC-MS.

<p>Sesquiterpenes produced by the recombinant PMSTS protein in <i>in vitro</i> enzymatic assay as detected by GC-MS.</p

HMGR assay using his-tag purified protein expressed from pNZ:<i>PMSTS</i>:<i>mvaA</i>.

<p>Protein expressed from his-tag purified pNZ:<i>PMSTS</i> was used as the negative control.</p

Schematic diagram of pNZ:<i>PMSTS</i> (A) and pNZ:<i>PMSTS</i>:<i>mvaA</i> (B) plasmids.

<p>Schematic diagram of pNZ:<i>PMSTS</i> (A) and pNZ:<i>PMSTS</i>:<i>mvaA</i> (B) plasmids.</p

GC-MS chromatogram showing sesquiterpenes produced from purified PMSTS protein.

<p>Summary of retention times, match score and percentages of sesquiterpenes produced are shown in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052444#pone-0052444-t001" target="_blank">Table 1</a>.</p

GC-MS chromatogram showing the <i>in vivo</i> production of β-sesquiphellandrene by clones harbouring the pNZ:<i>PMSTS</i> plasmid.

<p>The example shown here is for 40 ng/mL nisin induction at 2 h post-induction. B-sesquiphellandrene was detected at 7.24 min in the headspace of the induced culture (indicated by arrow) (A), which was undetected in the uninduced culture (B). Clones harbouring the pNZ:<i>PMSTS</i>:<i>mvaA</i> plasmid showed a similar GC-MS profile (data not shown).</p

Effect of a low-molecular-weight compatibilizer on the immiscible blends of cellulose acetate propionate and poly(butylene terephthalate)

[[abstract]]Blends of poly(butylene terephthalate) (PBT) and cellulose acetate propionate (CAP) were found to be immiscible. In order to improve the interfacial strength and miscibility of the PBT/CAP blends, a low-molecular-weight poly(ethylene glycol) (PEG) was thus pre-mixed with the CAP to form the P-CAP mixture. It was then blended with the PBT up to 15 wt% using a twin-screw extruder to prepare the PBT/P-CAP blends, and subsequently processed into the films and fibers by compression-molding and melt-spinning, respectively. The thermal and dynamic mechanical analyses suggested that the PBT and CAP became partially miscible and the interfacial strength was thus improved in the PBT/P-CAP blends, owing to the addition of PEG. The PEG was not only miscible with the CAP but also with the PBT, and it served as a plasticizer as well as a compatibilizer. From the observation of the fractured surface of the PBT/P-CAP films, the PBT component was present as dispersed particles in the P-CAP matrix with size ranging from 1.4 to 3.0 μm; yet it became nanofiber in the spun fibers. Successful fibers of the PBT/P-CAP blends with an average diameter of 20 μm could be spun, where the tensile strength and elongation at break were in the range of 0.6−0.7 g/denier and 12−16%, respectively. Finally, the ultra-fine PBT nanofibers with diameters in the range of 50−70 nm were observed after removing the P-CAP matrix with acetone from the fibers, owing to the formation of PBT nanofibers during spinning and orientation processes. This method thus could successfully produce nano-scale PBT fibers with fineness comparable with the nanofibers developed via electrospinning technology.[[notice]]補正完