Identification and Functional Analysis of Differentially Expressed Genes in Myzus persicae (Hemiptera: Aphididae) in Response to Trans-anethole.

Plant essential oils, with high bioactivity and biodegradability, provide promising alternatives to synthetic pesticides for pest control. Trans-anethole is the major component of essential oil from star anise, Illicium verum Hook. The compound has a strong contact toxicity against the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), which is a major insect pest of many vegetables and crops. However, little information is known about how M. persicae responds to trans-anethole at the molecular level. We conducted a comparative transcriptome analysis of M. persicae in response to a LD50 dose of trans-anethole. A total of 559 differentially expressed genes were detected in the treated individuals, with 318 genes up-regulated, and 241 genes down-regulated. Gene ontology (GO) analysis revealed that these genes were classified into different biological processes and pathways. We also found that genes encoding ATP-binding cassette (ABC) transporters, DnaJ, and cuticle proteins were dramatically up-regulated in response to trans-anethole. To study the function of these genes, we performed RNA interference (RNAi) analysis. Knockdown of an ABC transporter gene (ABCG4) and a DnaJ gene (DnaJC1) resulted in a significantly increased mortality rate in M. persicae following trans-anethole exposure, indicating the involvement of these two genes in the toxicity response to trans-anethole. The findings provide new insights into the mechanisms of M. persicae in coping with plant essential oils.

Effect of Different Iron Sources on In-Situ Growth of Zeolitic Imidazolate Frameworks-8: For Efficient Oxygen Reduction Electrocatalysts.

Transition metal and nitrogen co-doped carbon-based catalysts (TM-N-C) have become the most promising catalysts for Pt/C due to their wide range of sources, low cost, high catalytic activity, excellent stability and strong resistance to poisoning, especially Fe-N-C metal-organic frameworks (MOFs), which are some of the most promising precursors for the preparation of Fe-N-C catalysts due to their inherent properties, such as their highly ordered three-dimensional framework structure, controlled porosity, and tuneable chemistry. Based on these, in this paper, different iron sources were added to synthesis a sort of zeolitic imidazole frameworks (ZIF-8). Then the imidazole salt in ZIF-8 was rearranged into high N-doped carbon by high-temperature pyrolysis to prepare the Fe-N-C catalyst. We studied the physical characteristics of the catalysts by different iron sources and their effects on the catalytic properties of the oxygen reduction reaction (ORR). From the point of morphology, various iron sources have a positive influence on maintaining the morphology of ZIF-8 polyhedron. Fe-N/C-Fe(NO3)3 has the same anion as zinc nitrate, and can maintain a polyhedral morphology after high-temperature calcination. It had the highest ORR catalytic activity compared to the other four catalyst materials, which proved that there is a certain relationship between morphology and performance. This paper will provide a useful reference and new models for the development of high-performance ORR catalysts without precious metals.

Various Morphology of WO3 Modified Activated Carbon Supported Pd Catalysts with Enhanced Formic Acid Electrooxidation.

Activated carbon support Pd nanoparticles (NPs) modified by various WO3-shaped catalysts were prepared and applied as an efficient anode catalyst for direct formic acid fuel cells. Three forms of WO3 (nanosheets, nanoparticles, nanobars) modified activated carbon hybrids were first prepared via different syntheses, and then used as supports to synthesize three types of Pd-WO3/C catalysts by a NaBH4 reduction method. The morphology, structure, and electrochemical performances of the as-prepared Pd-WO3/C catalysts were characterized and analyzed. We can see that the noble metal particles loaded with activated carbon modified by WO3 exhibit small particle size and uniform dispersion from the transmission electron microscope image. The synthesized composite catalysts was used for the formic acid electrooxidation and showed excellent catalytic performance. The oxidation peak current density of the Pd/WO3-Nanosheets/C (40.04 mA·cm-2 was the highest, approximately 1.2 times that of Pd/C (33.00 mA·cm-2. Additionally, the long-term stability (i-t) test results show that the Pd/WO3-Nanosheets/C catalyst exhibits superior stability during formic acid electrooxidation. The reason for the increase in performance can be attributed to the following: the large specific surface area of WO3 decreases the adsorption strength of intermediates such as COad on Pd and prevents the accumulation of poisonous intermediates, thereby promoting the oxidation reaction of formic acid in the direct pathway; the catalyst-support interaction between precious metal Pd and WO3, substantially improving the catalytic performance of Pd-WO3/C catalysts.