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Surfactin has antiviral activity against various enveloped viruses by inhibiting viral membrane fusion. However, the potential utility of surfactin as an antiviral drug is limited by its cytotoxicity. In this study, 10 surfactin analogues were obtained by chemical synthesis and evaluated to determine their anti-PEDV activities, hemolytic activities, and critical micelle concentrations. The main goal of our study was to develop a safer drug; a surfactin analogue with high anti-PEDV activity and low hemolytic activity. Compared with surfactin, one of the analogues we developed, SLP5, has lower hemolytic activity, with the same antiviral activity. The selectivity index of SLP5 is 52, while the SI for surfactin is 4, in other words, the safe and effective concentration range of SLP5 is 12 times greater than that of surfactin. Like surfactin, SLP5 has a direct antiviral effect on PEDV. Structurally, SLP5 is a linear lipopeptide with three carboxyl groups. Surfactin derivatives similar to SLP5 could be obtained by lactone bond hydrolyzation of surfactin, as well as total synthesis. [ABSTRACT FROM AUTHOR]

Feeding preference is critical for insect adaptation and survival. However, little is known regarding the determination of insect feeding preference, and the genetic basis is poorly understood. As a model lepidopteran insect with economic importance, the domesticated silkworm, Bombyx mori, is a well-known monophagous insect that predominantly feeds on fresh mulberry leaves. This species-specific feeding preference provides an excellent model for investigation of host-plant selection of insects, although the molecular mechanism underlying this phenomenon remains unknown. Here, we describe the gene GR66, which encodes a putative bitter gustatory receptor (GR) that is responsible for the mulberry-specific feeding preference of B. mori. With the aid of a transposon-based, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 nuclease (Cas9) system, the GR66 locus was genetically mutated, and homozygous mutant silkworm strains with truncated gustatory receptor 66 (GR66) proteins were established. GR66 mutant larvae acquired new feeding activity, exhibiting the ability to feed on a number of plant species in addition to mulberry leaves, including fresh fruits and grain seeds that are not normally consumed by wild-type (WT) silkworms. Furthermore, a feeding choice assay revealed that the mutant larvae lost their specificity for mulberry. Overall, our findings provide the first genetic and phenotypic evidences that a single bitter GR is a major factor affecting the insect feeding preference. [ABSTRACT FROM AUTHOR]

Reference genes have been utilized in estimating gene expression levels using quantitative reverse transcriptase-quantitative polymerase chain reaction (qRT-PCR) analysis. Aphidius gifuensis Ashmaed is one of the most widely used biological control agents for aphids. The biological properties of this species have been studied in detail, and current investigations are focused on elucidating the regulatory mechanisms in its host However, the appropriate reference genes for target gene expression studies have not been identified. In this study, the expression profiles of 12 candidate reference genes were evaluated under different experimental conditions(development stage, sex, tissue type, diet) by using dedicated algorithms, including geNorm, Normfinder, BestKeeper, and ΔCt. In addition, RefFinder was used to rank the overall stability of the candidate genes. Finally, we recommend three optimal reference genes for the normalization of qRT-PCR data in the presence of specific variables, which include ACTB, RPL13, and PPI for different developmental stages; RPS18, ACTB, and RPL13 for sexes; RPL13, PRII3, and RPS18 in different tissue types; and RPL13, RPL27, and ACTB in diverse diets. The present study has identified optimal reference genes that could be used in estimating the expression levels of specific genes under these conditions following the Minimum Information for publication of Quantitative real-time PCR Experiments (MIQE) guidelines, which would facilitate in advancements in functional genomics research on A. gifuensis. [ABSTRACT FROM AUTHOR]