昆虫分子生物学合辑Insect Molecular Biology

Select

Identification and characterization of a TLR13 gene homologue from Laodelphax striatellus involved in the immune response induced by rice stripe virus

ZHOU Xue, HU Jia, FU Mei-li, JIN Ping, ZHANG Yun-ye, XIANG Ying, LI Yao, MA Fei

2020, 19 (1): 183-192. DOI: 10.1016/S2095-3119(19)62795-4

Abstract （196） PDF in ScienceDirect

Toll-like receptors (TLRs) are the critical superfamily homologues that initiate sensing of the invasion of pathogens by the Toll pathway. As one of several intracellular nucleic acid-sensing TLRs, TLR13 is activated by an unmethylated motif present in the large ribosomal subunit of bacterial RNA. However, little attention has been paid to the function of TLR13 gene homologue from Laodelphax striatellus (designated as LsToll-13) in the immune response to rice stripe virus (RSV). Herein, LsToll-13 was cloned and characterized using RACE-PCR. Phylogenetic analysis showed that LsToll-13 was clustered with the TLR13 from six insects. Real-time PCR analysis demonstrated that the expression level of LsToll-13 was significantly reduced in L.?striatellus with RSV infection compared with that in the naive strain. When the expression of LsToll-13 was significantly up-regulated at 6 h after bacterial infection, the expression of ribonucleoprotein (RNP) indicated that the RSV titer in the host insect was significantly suppressed. Upon knockdown of LsToll-13, using RNA interference (RNAi) in L.?striatellus, the expression level of RNP was significantly increased with enhanced RSV accumulation, suggesting that LsToll-13 potentially protects L.?striatellus from RSV infection. Taken together, our results indicated that LsToll-13 might be involved in the immune response of L.?striatellus to RSV infection, and provided a new insight into further elucidating the molecular mechanisms of complex pathogen-host interactions and integrative pest management.

Reference | Related Articles | Metrics

Select

Molecular characteristics and temperature tolerance function of the transient receptor potential in the native Bemisia tabaci AsiaII3 cryptic species

JI Shun-xia, SHEN Xiao-na, LIANG Lin, WANG Xiao-di, LIU Wan-xue, WAN Fang-hao, Lü Zhi-chuang

2020, 19 (11): 2746-2757. DOI: 10.1016/S2095-3119(20)63226-9

Abstract （109） PDF in ScienceDirect

Insects are poikilothermic animals, and temperature is one of the most important abiotic factors affecting their spread and distribution. For example, differences in thermal tolerance may underlie the significant differences in geographical distributions between the native AsiaII3 and invasive MED (Mediterranean) cryptic Bemisia tabaci species in China. Transient receptor potential (TRP) channels are key components of the insect temperature perception system and act as molecular thermometers since they can be activated by specific changes in temperature. In this study, we cloned and characterized the AsiaII3 BtTRP gene and revealed its functions in the response to thermal stress. The full-length cDNA of BtTRP was 3 821 bp, with a 3 501-bp open reading frame encoding a 132.05-kDa protein. Comparing the deduced amino acid sequences of AsiaII3 BtTRP and MED TRP revealed five amino acid differences. In situ hybridization indicated that BtTRP might be widely expressed throughout the AsiaII3 adult body. BtTRP mRNA expression reached the highest levels after exposure to mild thermal stimuli (12 and 35°C), showing that BtTRP expression can be induced by temperature stress. Furthermore, the thermal tolerance of AsiaII3 after BtTRP dsRNA feeding was significantly lower than that of the control. Taken together, the present study highlights the importance of TRP channels for B.?tabaci thermal resistance, and allows us to infer that the differences in amino acids between AsiaII3 and MED might cause the differences in thermal tolerance of these two cryptic species. This study provides a new direction for investigating geographic distribution differences between invasive and native insects.

Reference | Related Articles | Metrics

Select

Pancreatic triglyceride lipase is involved in the virulence of the brown planthopper to rice plants

YUAN Long-yu, HAO Yuan-hao, CHEN Qiao-kui, PANG Rui, ZHANG Wen-qing

2020, 19 (11): 2758-2766. DOI: 10.1016/S2095-3119(20)63188-4

Abstract （106） PDF in ScienceDirect

The brown planthopper (BPH), Nilaparvata lugens, an important rice insect pest, can enhance its virulence to BPH-resistant rice within as short a span as several generations. Here, we cloned a pancreatic triglyceride lipase (PTL) gene (NlPTL) in N. lugens, and found that its mRNA level was higher in the high virulence population (fed on variety Rathu Heenati, P-RH) than in the low virulence population (fed on variety Taichung Native 1, P-TN1). Knocking down NlPTL caused BPH individuals to spend more time in non-penetration and the pathway phases and less time feeding on the phloem of rice plants; these changes consequently decreased food intake, lipid content, survival rate, and fecundity in the insects. These findings reveal for the first time that PTL in BPH is involved in its virulence to rice plants.

Reference | Related Articles | Metrics

Select

Cloning and functional characterization of two peptidoglycan recognition protein isoforms (PGRP-LC) in Bactrocera dorsalis (Diptera: Tephritidae)

WEI Dong, WANG Zhe, XU Hui-qian, NIU Jin-zhi, WANG Jin-jun

2020, 19 (12): 3025-3034. DOI: 10.1016/S2095-3119(20)63202-6

Abstract （81） PDF in ScienceDirect

The innate immune system of insects is the front line of self-defense against pathogen invasion. Peptidoglycan recognition proteins (PGRPs) are important components and play key roles in insect immune systems by recognizing peptidoglycan (PGN) in bacterial cell walls. We characterized two isoforms of the PGRP-LC gene, BdPGRP-LCa and BdPGRP-LCb, from Bactrocera dorsalis (Hendel), an important fruit and vegetable pest worldwide. These two isoforms contain an open reading frames of 1 668 bp and 1 731 bp, encoding a protein of 555 and 576 amino acids, respectively. Quantitative real-time PCR results showed that both transcripts were prominently expressed in midgut and fat body of B. dorsalis adult. Inoculation of pathogens showed that both isoforms actively responded to Escherichia coli PGN. We also observed a light response to Staphylococcus aureus PGN. Upon Beauveria bassiana inoculation, the expression of BdPGRP-LCa was enhanced, but the expression of BdPGRP-LCb was suppressed. Suppression of both transcripts by RNA interference led to increased mortality of flies challenged by E. coli, indicating that the two isoforms are involved in sensing Gram-negative bacterial infections.

Reference | Related Articles | Metrics

Select

Cuticular protein gene LmACP8 is involved in wing morphogenesis in the migratory locust, Locusta migratoria

ZHAO Xiao-ming, YANG Jia-peng, GOU Xin, LIU Wei-min, ZHANG Jian-zhen

2021, 20 (6): 1596-1606. DOI: 10.1016/S2095-3119(20)63248-8

Abstract （111） PDF in ScienceDirect

Cuticular proteins (CPs) are major components of the insect cuticle-associated organs such as integument and wings, although the importance of CPs for wing development and function in hemimetabolous insects remains understudied. In the present study, a wing cuticular protein LmACP8 was identified from Locusta migratoria, which belongs to the RR-2 subfamily of cuticular protein R&R consensus (CPR) chitin-binding proteins. LmACP8 was mainly expressed in the wing pads and showed high expression levels before ecdysis of third-, fourth-, and fifth-instar nymphs, with its encoded protein located in the procuticle of wing pads and adult wings. Depletion of LmACP8 by RNA interference markedly reduced the amount of its protein, which consequently caused abnormal wing morphogenesis in the transition from nymph to adult of L. migratoria. We further demonstrated that the abnormal morphogenesis was caused by severe damage of the endocuticle in the wings. LmACP8 was suppressed by 20-hydroxyecdysone (20E) in vivo, however, its expression was significantly up-regulated after knocking down the hormone receptor gene LmHR39. Thus, the LmACP8 that is negatively regulated by the LmHR39-mediated 20E signaling pathway is involved in wing development during the nymph to adult transition.

Reference | Related Articles | Metrics

Select

Functional analysis of the orphan genes Tssor-3 and Tssor-4 in male Plutella xylostella

LI Tian-pu, ZHANG Li-wen, LI Ya-qing, YOU Min-sheng, ZHAO Qian

2021, 20 (7): 1880-1888. DOI: 10.1016/S2095-3119(21)63655-9

Abstract （129） PDF in ScienceDirect

Orphan genes are genes with no sequence homologues in other species. Here, we identified two orphan genes, namely, Tssor-3 and Tssor-4, in Plutella xylostella. Both genes contained a signal peptide sequence, suggesting their functions as secreted proteins. Expression pattern analysis based on real-time quantitative PCR (qPCR) showed that both orphan genes were specifically expressed in all male gonads except the testes. The expression of both the orphan genes peaked at the male adult stage. Immunofluorescence assays suggested that the two proteins were seminal proteins, indicating their potential roles in male reproductive regulation. To further explain their functions, we knocked down the expression of these two genes by RNA interference (RNAi). The results showed that the expression of Tssor-3 and Tssor-4 was significantly downregulated at 24 h after injection compared to that of the controls. Biological assays showed that the number of laid eggs and the hatching rate of offspring eggs were significantly reduced when the expression of Tssor-3 and Tssor-4 was reduced, suggesting that the two orphan genes played a role in male fertility in P. xylostella. Our results provide evidence that orphan genes are involved in male reproductive regulation, which is important for male fitness during evolution.

Reference | Related Articles | Metrics

Select

Identification and tissue distribution of odorant binding protein genes in Harmonia axyridis (Coleoptera: Coccinellidae)

QU Cheng, WANG Ran, CHE Wu-nan, LI Feng-qi, ZHAO Hai-peng, WEI Yi-yun, LUO Chen, XUE Ming

2021, 20 (8): 2204-2213. DOI: 10.1016/S2095-3119(20)63297-X

Abstract （119） PDF in ScienceDirect

The olfactory system of insects is crucial in modulating behaviors such as host seeking, mating, and oviposition. Odorant-binding proteins (OBPs) are involved in semiochemical recognition. OBPs recognize and bind odorants and transport them to odorant receptors located in olfactory neurons. Harmonia axyridis (Coleoptera: Coccinellidae) is a widely used predacious biological control agent for many agricultural and forestry pests. This study identified 19 OBPs in H.?axyridis based on the antennal and whole-body transcriptomes of adults and obtained all the full-length open reading frames, including 11 ‘Classic’ OBPs, 7 ‘Minus-C’ OBPs and 1 ‘Plus-C’ OBP. They encoded 125 to 241 amino acid proteins with molecular weights ranging from 13.75 to 27.75 kDa and isoelectric points ranging from 4.15 to 8.80. Phylogenetic analyses were used to study the relationships between H.?axyridis OBPs and OBPs from other species of Coleoptera. Quantitative real-time PCR (qPCR) analysis showed that HaxyOBP2, 3, 5, 8, 10, 12, 13, 14, and 15 were highly expressed in antennae of both adult females and males. Moreover, HaxyOBP2, 3, 5, 12, and 15 were more abundantly expressed in antennae than other body parts, while HaxyOBP13 and HaxyOBP14 were expressed predominantly, and at similar levels, in the head and antennae. The other OBP genes were highly expressed in non-olfactory tissues including the thorax, abdomen, legs, and wings. These results provide valuable information for further study of H.?axyridis olfaction, which may ultimately enhance its use as a biocontrol agent.

Reference | Related Articles | Metrics

Select

Stability evaluation of reference genes for real-time quantitative PCR normalization in Spodoptera frugiperda (Lepidoptera: Noctuidae)

SHU Ben-shui, YU Hai-kuo, DAI Jing-hua, XIE Zi-ge, QIAN Wan-qiang, LIN Jin-tian

2021, 20 (9): 2471-2482. DOI: 10.1016/S2095-3119(20)63298-1

Abstract （150） PDF in ScienceDirect

Real-time quantitative PCR (qPCR) is a reliable and widely used technique for analyzing the expression profiles of target genes in different species, and reference genes with stable expressions have been introduced for the normalization of the data. Therefore, stability evaluation should be considered as the initial step for qPCR experiments. The fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is a polyphagous pest that consumes many plant species and seriously threatens corn production around the world. However, no studies thus far have examined the stability of reference genes in this pest. In this study, the expression profiles of the eight candidate reference genes of Actin, elongation factor 1 alpha (EF1α), elongation factor 2 (EF2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ribosomal protein L3 (RPL3), ribosomal protein L13 (RPL13), alpha-tubulin (α-TUB), and beta-1-tubulin (β-1-TUB) were obtained from S. frugiperda in different samples and the stability was evaluated by ΔCt, BestKeeper, geNorm, NormFinder, and RefFinder methods. The results of pairwise variation (V) calculated by GeNorm indicated two reference genes could be selected for normalization. Therefore, the combinations of the most stable reference genes for different experimental conditions of S. frugiperda were shown as follows: EF2 and RPL13 for developmental stages, RPL3 and β-1-TUB for larval tissue samples, EF2 and EF1α for the larval samples treated with different temperatures, RPL3 and EF1α for the larval samples under starvation stress, and RPL13 and EF1α for all the samples. Our results lay the foundation for the normalization of qPCR analyses in S. frugiperda and could help guarantee the accuracy of subsequent research.

Reference | Related Articles | Metrics

Select

Functional identification of C-type lectin in the diamondback moth, Plutella xylostella (L.) innate immunity

LI Jin-yang, LIN Jun-han, G. Mandela FERNáNDEZ-GRANDON, ZHANG Jia-yu, YOU Min-sheng, XIA Xiao-feng

2021, 20 (12): 3240-3255. DOI: 10.1016/S2095-3119(21)63650-X

Abstract （160） PDF in ScienceDirect

C-type lectins (CTLs) are a superfamily of Ca²⁺-dependent carbohydrate-recognition proteins, and an important pattern recognition receptor (PRR) in insect innate immunity which can mediate humoral and cellular immunity in insects. In this study, we report a novel dual carbohydrate-recognition domain (CRD) CTL from Plutella xylostella which we designate PxIML. PxIML is a protein with a 969 bp open reading frame (ORF) encoding 322 amino acids, containing a signal peptide and a dual-CRD with EPN (Glu₁₂₄-Pro₁₂₅-Asn₁₂₆) and QPD (Gln₂₇₄-Pro₂₇₅-Asp₂₇₆) motifs. The expression of PxIML mRNA in the fat body was significantly higher than in hemocytes and midgut. The relative expression levels of PxIML in the whole insect and the fat body were significantly inhibited after infection with Bacillus thuringiensis 8010 (Bt8010) at 18 h, while they were significantly upregulated after infection with Serratia marcescens IAE6 or Pichia pastoris. The recombinant PxIML (rPxIML) protein could bind to the tested pathogen-associated molecular patterns (PAMPs), and the bacteria of Enterobacter sp. IAE5, S. marcescens IAE6, Staphylococcus aureus, Escherichia coli BL21, and Bt8010 in a Ca²⁺-dependent manner, however, it showed limited binding to the fungus, P. pastoris. The rPxIML exhibited strong activity in the presence of Ca²⁺ to agglutinate Bt8010, Enterobacter sp. IAE5 and S. aureus, but it only weakly agglutinated with E. coli BL21, and could not agglutinate with S. marcescens IAE6 or P. pastoris. Furthermore, the rPxIML could bind to hemocytes, promote the adsorption of hemocytes to beads, and enhance the phenoloxidase (PO) activity and melanization of P. xylostella. Our results suggest that PxIML plays an important role in pathogen recognition and in mediating subsequent humoral and cellular immunity of P. xylostella.

Reference | Related Articles | Metrics

Virtual Issue

About JIA

Editorial board

For authors