The First Eight Mitogenomes of Leaf-Mining Dactylispa Beetles (Coleoptera: Chrysomelidae: Cassidinae) Shed New Light on Subgenus Relationships.

The taxonomic classification of Dactylispa, a large genus of leaf-mining beetles, is problematic because it is currently based on morphology alone. Here, the first eight mitochondrial genomes of Dactylispa species, which were used to construct the first molecular phylogenies of this genus, are reported. The lengths of the eight mitogenomes range from 17,189 bp to 20,363 bp. All of the mitochondrial genomes include 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and 1 A + T-rich region. According to the nonsynonymous/synonymous mutation ratio (Ka/Ks) of all PCGs, the highest and the lowest evolutionary rates were found for atp8 and cox1, respectively, which is a common phenomenon among animals. According to relative synonymous codon usage, UUA(L) has the highest frequency. With two Gonophorini species as the outgroup, mitogenome-based phylogenetic trees of the eight Dactylispa species were constructed using maximum likelihood (ML) and Bayesian inference (BI) methods based on the PCGs, tRNAs, and rRNAs. Two DNA-based phylogenomic inferences and one protein-based phylogenomic inference support the delimitation of the subgenera Dactylispa s. str. and Platypriella as proposed in the system of Chen et al. (1986). However, the subgenus Triplispa is not recovered as monophyletic. The placement of Triplispa species requires further verification and testing with more species. We also found that both adult body shape and host plant relationship might explain the subgeneric relationships among Dactylispa beetles to a certain degree.

The complete mitochondrial genome of Downesia tarsata (Coleoptera: Chrysomelidae: Cassidinae).

Downesia species are leaf-mining beetles mainly feed on Poaceae plants in the tropical and subtropical areas in Asia. In this study, we firstly sequenced and reported the complete mitochondrial genome for the genus. The complete mitogenome of Downesia tarsata is 18,557 bp in length, including 13 protein-coding genes (PCG), 22 transfer RNA (tRNA), two ribosomal RNA (rRNA), and one AT-rich region. Phylogenomic analysis indicated that D. tarsata is closely related to Agonita chinensis, and the two species belong to the same tribe of Gonophorini. The complete mitochondrial genome of D. tarsata could help clarify the phylogenetic relationship among Cassidinae species.

Melt-diffusion and ion-exchange methods: self-triggered O-rich groups on the surface of acetylene black using S-EDA solution to boost its sulfur content for lithium-sulfur batteries.

Only a few studies have described the use of H+-attacking S-EDA in nucleophilic substitution reactions to bind frameworks and sulfur in cathode materials, which is also known as the ion-exchange method. The pros and cons of this method are still unclear in relation to lithium-sulfur battery applications. Here, the influences of two synthetic routes, a melt-diffusion method and H+ reacting with S-EDA via nucleophilic substitution, on the morphologies and electrochemical properties of cathode materials are discussed in detail based on in situ XRD and other advanced technologies. Accordingly, high S-loading is achieved when H+ reacts with S-EDA via ion exchange on the surface of acetylene black, and capacities of 693.8, 644.5, and 638.9 mA h g-1 are obtained over the first three cycles when the C/S composite is used as a cathode in coin cells without the conductive additive Super P. In situ XRD data confirm that poor electrochemical properties can mainly be attributed to the conversion rate of S species being too rapid to thoroughly utilize the S molecules that are immobilized, which means that more fixed sulfur can form during the charge/discharge process when using the ion-exchange method to make the C/S composite. In addition, a long-chain polysulfide shuttling effect is directly noticed via AFM in tapping-KPFM mode in the C/S composite that was synthesized via the melt-diffusion method, even though polar S-O bonds exist in the composite. The increase in the cathodic surface potential from 102.8 to 141.1 mV and the increase in the morphological height from 547.7 to 829.7 nm during the discharge/charge process can be attributed to the process of S loss.

Synthesis of Methyl-Capped TiO2-SiO2 Janus Pickering Emulsifiers for Selective Photodegradation of Water-Soluble Dyes.

Recently, Pickering emulsion stabilized by Janus particles has received considerable attention for interfacial reactions and droplet manipulation. However, its potential interests have been rarely explored because of the difficulties in designing and fabricating Janus particles for Pickering emulsion with suitable applications. Also, photocatalytic materials are scarcely applied as emulsifiers in Pickering emulsions because of their photogenerated hydrophilicity. This work reports the synthesis of methyl-capped Janus TiO2-SiO2 particles (MJTSs), which can be used as a novel emulsifier and photocatalyst simultaneously. The MJTSs, composed of an anatase TiO2 sphere and silica rod, are prepared by inverse emulsion-based step-by-step growth. We demonstrate that the Pickering emulsion stabilized by MJTSs represents extraordinary ability of emulsification, excellent stability, and tunable emulsion type (water in oil or oil in water). In addition, the MJTSs exhibit photocatalytic activity in decomposition of pollutants in the water phase while maintaining the stability of the Pickering emulsion.

Complete Mitogenome of a Leaf-Mining Buprestid Beetle, Trachys auricollis, and Its Phylogenetic Implications.

A complete mitogenome of Trachys auricollis is reported, and a mitogenome-based phylogenetic tree of Elateriformia with all protein-coding genes (PCGs), rRNAs, and tRNAs is presented for the first time. The complete mitochondrial genome of T. auricollis is 16,429 bp in size and contains 13 PCGs, two rRNA genes, 22 tRNA genes, and an A + T-rich region. The A + T content of the entire genome is approximately 71.1%, and the AT skew and GC skew are 0.10 and -0.20, respectively. According to the the nonsynonymous substitution rate to synonymous substitution rates (Ka/Ks) of all PCGs, the highest and lowest evolutionary rates were observed for atp8 and cox1, respectively, which is a common finding among animals. The start codons of all PCGs are the typical ATN. Ten PCGs have complete stop codons, but three have incomplete stop codons with T or TA. As calculated based on the relative synonymous codon usage (RSCU) values, UUA(L) is the codon with the highest frequency. Except for trnS1, all 22 tRNA genes exhibit typical cloverleaf structures. The A + T-rich region of T. auricollis is located between rrnS and the trnI-trnG-trnM gene cluster, with six 72-bp tandem repeats. Both maximum likelihood (ML) and Bayesian (BI) trees suggest that Buprestoidea is close to Byrrhoidea and that Buprestoidea and Byrrhoidea are sister groups of Elateroidea, but the position of Psephenidae is undetermined. The inclusion of tRNAs might help to resolve the phylogeny of Coleoptera.