The 20S proteasome is a core component of the ubiquitin-proteasome system, participating in various biological processes such as cell cycle regulation, signal transduction, apoptosis, and protein homeostasis. However, its roles in mammals are well-documented, its function in the insect intestine remains largely unexplored. In this study, we identified 14 20S proteasome subunits, including 7 α-subunits and 7 β-subunits in Locusta migratoria , a worldwide agricultural pest. Phylogenetic tree revealed conservation of amino acid sequences among different species. While the conserved domains and motifs analysis exhibited both conservation and divergence among 20S proteasome subunits. The expression pattern of 20S proteasome subunits found that these subunits were expressed in all growth phases. Notably, a large number of 20S proteasome subunits were found to be expressed in ovary and midgut tissues. We further demonstrated that, except for increased expression of proteasome α7 and β5, other proteasome subunits were significantly reduced under 3 % dextran sulphate sodium condition. Additionally, the expression of 8 of 14 proteasome subunits were down-regulated after malathion treatment. However, the expression of most proteasome β subunits decreased significantly after deltamethrin treatment. RNAi targeting 20S proteasome subunits resulted in complete mortality in fifth-instar nymphs, midgut and gastric cecum atrophy, and significant reductions in body length and weight. Moreover, silencing of 20S proteasome subunits impaired ovarian growth. Furthermore, 20S proteasome subunits are also potential target genes for RNAi-based pest control strategies.
Ke Su,Guoqiang Xiang,Xinrong Jin,Xin Wang,Xiuming Jiang,Lijun He,Wenjie Zhao,Yaming Sun,Chen Cui
Locust powder was converted into water-soluble fluorescent nitrogen-doped carbon dots (N-CDs) with gram-scale yield through a self-exothermic reaction between nitric acid and diethylenetriamine (DETA) within 10 min. The morphology, elemental information, and optical properties of the N-CDs were characterized using high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared, ultraviolet–visible and fluorescence spectroscopy. Spectroscopic investigation indicated that the fluorescence emission behaviour of N-CDs is excitation wavelength dependent, with the strongest emission peak at 470 nm using a 390 nm excitation wavelength. The strong absorption peak of sunset yellow (SY) at 482 nm overlaps substantially with the blue emission peak (470 nm) of N-CDs. This enables the fluorescence emission of N-CDs to be obviously quenched by SY through the inner filter effect. There was a good linear relationship between the fluorescence quenching degree and the concentrations of SY within the range 0.5–40 μM. The detection limit of developed fluorescence assay for SY is 28 nM, and the relative standard deviation is 2.3% (c = 10 μM). The N-CDs derived from locusts by the self-exothermic reaction are highly selective and sensitive fluorescent probes for SY, which were applied to the fluorescence sensing of SY in different food samples with satisfactory results.
Ke Su,Guoqiang Xiang,Chen Cui,Xiuming Jiang,Yaming Sun,Wenjie Zhao,Lijun He
In this study, nitrogen-doped carbon dots ( N -CDs) with excellent peroxidase-like activity were prepared using locust powder as the carbon source by a self-exothermic reaction. The obtained N -CDs could catalyze the oxidation of the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H 2 O 2 to generate a blue oxidized product (TMB ox ) with a maximum absorption peak at 654 nm. The catalytic reaction conditions were optimized; furthermore, steady-state kinetic analysis indicated that N -CDs exhibited high affinity toward both TMB and H 2 O 2 , and the Michaelis-Menten constant (k m ) values were 0.115 mM (TMB) and 0.764 mM (H 2 O 2 ). A smartphone-based colorimetric method was developed for quantitative detection. The 1/L values (L stands for lightness in HSL color space) of the TMB ox solution were recorded via an iPhone application Color Analyzer. Since H 2 O 2 is the by-product of glucose (Glu) oxidation in the presence of glucose oxidase (GOx), a simple, sensitive, and selective smartphone-based colorimetric method was developed for the determination of Glu, and the detection limit was 1.09 μM. The smartphone-based method was successfully applied to determine Glu in different food samples with recoveries in the range of 88.5–109.0 %.
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