Immune signaling pathways and digestion-related proteins in the Manduca sexta larvae

M. sexta has been used as a biochemistry model to study insect immunity. While it is unclear how immune genes are specifically regulated by Toll or Imd pathway. We produced the recombinant Spätzle-1 and -2 precursors, activated them using prophenoloxidase activating protease-3 (PAP3), and separately injected them into hemocoel to trigger specific up-regulation of genes controlled by the Toll pathway. M. sexta cell line was treated with E. coli DAP-PG to specifically induce the Imd pathway. RNA-seq analysis of fat body tissues and cell samples indicated that diapausins and lebocins are predominantly regulated via Toll signaling, gallerimycin, X-tox and its splicing variants are synthesized in response to DAP-PG through Imd pathway, whereas attacins, cecropins, moricins, defensins, gloverin, lysozymes, transferrins, and WAPs are induced via both. Furthermore, we separately injected Enterococcus faecalis or Enterobacter cloacae into hemocoel, it showed that most antimicrobial peptides could be induced by both bacteria, such as lebocinD, which is a Toll-specific gene. However, diapausin1, gloverin and cecropin6 were more sensitive to Enterococcus faecalis, X-toxs was more sensitive to Enterobacter cloacae. Our results showed the injection of bacteria cannot separate Toll or Imd pathways properly in M. sexta, which is very different from D. melanogaster. Thus, it confirms the complexity of host-pathogen interactions and innate immune response pathways in other non-dipteran insects.Food digestion is vital for the survival and prosperity of insects. While digestive enzymes from pest species lacks a systematic analysis. In the genome of Manduca sexta, we identified 122 digestive enzymes including 85 proteases, 20 esterases, 16 carbohydrases, and 1 nuclease. We also further categorized 144 M. sexta serine esterases (SEs) and their homologs, 26 phospholipases and 13 thioesterases. Expression profiling of these genes in specific tissues and stages has provided insights into their functions including digestion, detoxification, hormone processing, neurotransmission, reproduction, and developmental regulation. In summary, these studies provide for the first time a holistic view of the digestion and SE-related proteins in a model lepidopteran insect and clues for comparative research in lepidopteran pests and beyond

The Genome of Rhyzopertha dominica (Fab.) (Coleoptera: Bostrichidae): Adaptation for Success

The lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), is a major global pest of cereal grains. Infestations are difficult to control as larvae feed inside grain kernels, and many populations are resistant to both contact insecticides and fumigants. We sequenced the genome of R. dominica to identify genes responsible for important biological functions and develop more targeted and efficacious management strategies. The genome was assembled from long read sequencing and long-range scaffolding technologies. The genome assembly is 479.1 Mb, close to the predicted genome size of 480.4 Mb by flow cytometry. This assembly is among the most contiguous beetle assemblies published to date, with 139 scaffolds, an N50 of 53.6 Mb, and L50 of 4, indicating chromosome-scale scaffolds. Predicted genes from biologically relevant groups were manually annotated using transcriptome data from adults and different larval tissues to guide annotation. The expansion of carbohydrase and serine peptidase genes suggest that they combine to enable efficient digestion of cereal proteins. A reduction in the copy number of several detoxification gene families relative to other coleopterans may reflect the low selective pressure on these genes in an insect that spends most of its life feeding internally. Chemoreceptor genes contain elevated numbers of pseudogenes for odorant receptors that also may be related to the recent ontogenetic shift of R. dominica to a diet consisting primarily of stored grains. Analysis of repetitive sequences will further define the evolution of bostrichid beetles compared to other species. The data overall contribute significantly to coleopteran genetic research

Binary Fe, Cu-doped bamboo-like carbon nanotubes as efficient catalyst for the oxygen reduction reaction

In this work, CuCl2 as a promoter was added into the mixture of polythiophene (PTh), FeCl3, and melamine for preparing Fe-Cu-N/C catalyst. The catalyst features one-dimensional bamboo-like carbon nanotubes with few metal oxide nanoparticles encapsulated into tubes. The catalyst exhibits excellent activity toward the oxygen reduction reaction (ORR) with half-wave potential 50 mV more positive than the commercial Pt/C in 0.1 M KOH. It also shows comparable ORR activity in 0.1 M HClO4 solution. Moreover, it exhibits superior long-term stability and excellent methanol tolerance in both alkaline and acidic solutions. The outstanding catalytic performance of Fe-Cu-N/C catalyst can be ascribed to the doping of Cu in the Fe-N-C architecture, which promotes the formation of bamboo-like nanotube structure and the generation of interaction among Cu and Fe-N-C. This synthetic strategy may open new avenues for constructing highly efficient electrocatalysts that adding of an inactive metal can obviously promote the catalytic performance of catalysts

Highly Selective Conversion of Carbon Dioxide to Lower Olefins

Conversion of CO₂ to value-added chemicals has been a long-standing objective, and direct hydrogenation of CO₂ to lower olefins is highly desirable but still challenging. Herein, we report a selective conversion of CO₂ to lower olefins through CO₂ hydrogenation over a ZnZrO/SAPO tandem catalyst fabricated with a ZnO-ZrO₂ solid solution and a Zn-modified SAPO-34 zeolite, which can achieve a selectivity for lower olefins as high as 80–90% among hydrocarbon products. This is realized on the basis of the dual functions of the tandem catalyst: hydrogenation of CO₂ on the ZnO-ZrO₂ solid solution and lower olefins production on the SAPO zeolite. The thermodynamic and kinetic coupling between the tandem reactions enable the highly efficient conversion of CO₂ to lower olefins. Furthermore, this catalyst is stable toward the thermal and sulfur treatments, showing the potential industrial application