The basic helix–loop–helix transcription factors in the Colorado potato beetle Leptinotarsa decemlineata

Kai-Yun Fu,Qing-Wei Meng,Feng-Gong Lüa,Wen-Chao Guo,Tursun Ahmat,Guo-Qing Li 한국응용곤충학회 2015 Journal of Asia-Pacific Entomology Vol.18 No.2

The basic helix–loop–helix (bHLH) transcription factors possess crucial functions in cell proliferation, determination, differentiation, cell cycle maintenance and homeostasis or stress response pathways. Since a few juvenile hormone analogues such as hydroprene, methoprene and pyriproxyfen targeting a bHLH member Met are already registered for pest management, there is a potential to develop more insecticides targeting various bHLHs. The identification of bHLH members is the first step. Based on the transcriptome and the genome of the Colorado potato beetle Leptinotarsa decemlineata, the most important pest in potato, 49 bHLH members were identified. All LdbHLH memberswere defined by their names and families according to various phylogenetic analyses with bHLH homologues of Drosophila melanogaster, Apis mellifera, Bombyx mori and Tribolium castaneum. Among these LdbHLHs, 17, 10, 10, 1, 10 and 1 members belonged to A, B, C, D, E and F high-order groups, respectively. The results would provide useful background information for future studies on functions of bHLH proteins in the regulation of L. decemlineata development. Moreover, the bHLHs could serve as potential insecticide targets. These proteins could be used in small molecule screen, or in the development of RNAi-based pest management methods.

The complete mitochondrial genome of Tuta absoluta (Lepidoptera: Gelechiidae) and genetic variation in two newly invaded populations in China

Li Xiao-wei,Fu Kai-Yun,Guo Wen-Chao,Wang Tian-zhen,Lu Yao-bin 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.4

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a devastating invasive pest worldwide, causing severe damage to tomatoes. Recently, it has been recorded in the northwestern and southwestern parts of China. Here, the mitogenomes and genetic variation of two newly invaded T. absoluta populations in Xinjiang and Yunnan, were determined. The results showed that the complete mitogenome size of T. absoluta is 15298 bp for the in dividual from Xinjiang and 15296 bp for the individual from Yunnan, which were both longer than the reported mitogenome from Spain (15290 bp). The mitogenome sequences of individuals collected from three locations showed high levels of sequence similarity, except for 8 polymorphic sites, which were in genes cox2 (1 site), cox3 (2 sites), cob (1 site), atp6 (1 site), nad1 (2 sites) and nad5 (1 site). Tuta absoluta mitogenomes share many features with other 6 Gelechiidae mitogenomes, except for several differences in the start and stop codons of protein-coding genes and the length of intergenic spacers. Seven partial mitochondrial genes (cox1, cox2, cox3, atp6, cob, nad1, and nad5) were used for genetic variation analysis, and significant population differentiation was found between the two populations based on cox2, atp6, nad1, and nad5. The complete mitogenomes and sen sitive mitochondrial gene markers reported here provide useful data for further population genetics study of this pest.

Two Androstane Derivatives from the Cultures of Fungus Marasmiellus ramealis (Bull.) Singer

Ning-Ning Yang,Qing-Yun Ma,Sheng-Zhuo Huang,Hao-Fu Dai,Zhi-Kai Guo,Zhi-Fang Yu,You-Xing Zhao 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.11

A new androstane derivative, 4β-methyl-15-oxa-14β-androstane-7-ene-4α-carboxylic acid (1) and a known one 4β-methyl-15-oxa-14β-androstane-7-ene-4α-hydroxyl (2) were isolated from the EtOAc extract of the cultures of the fungus Marasmiellus ramealis (Bull.) Singer. Their structures were elucidated on the basis of 1D and 2D NMR as well as MS spectroscopic data analysis. The inhibitory activity of two isolates against acetylcholinesterase (AChE) revealed that compound 1 exhibited definitely inhibitory activity.

Two New Phenolic Compounds from the Fruiting Bodies of Ganoderma tropicum

Li-Li Hu,Qing-Yun Ma,Sheng-Zhuo Huang,Zhi-Kai Guo,Jianchun Guo,Hao Fu Dai,You-Xing Zhao 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.3

Chemical investigation of the fruiting bodies of Ganoderma tropicum led to the isolation of two new phenolic compounds, ganodermatropins A (1) and B (2). Their structures were elucidated by spectroscopic techniques (MS, 1D and 2D NMR). Ganodermatropin A exhibited antimicrobial activity against Staphylococcus aureus.

Eclosion hormone functions in larva-pupa-adult ecdysis in Leptinotarsa decemlineata

Shen Chen-Hui,Jin Lin,Fu Kai-Yun,Guo Wen-Chao,Li Guo-Qing 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.1

In Drosophila melanogaster, ecdysis-triggering hormone (ETH) and eclosion hormone (EH) mutually enhance the release of each other through a positive feedback loop. Both are involved in the stimulation of ecdysis behavior series and molting-related physiological preparations. However, whether 20-hydroxyecdysone (20E) controls eh expression and whether EH plays a similar role in non-Drosophilid insects remain to be determined. In Lep tinotarsa decemlineata, we found that Ldeh mRNA levels were high in the early and/or late stages and low in the intermediate period within each larval instar, indicating that the mRNA peaks positively correlate with 20E pulses. Consistent with the indication, we confirmed that 20E signaling stimulated the transcription of Ldeh. RNA interference (RNAi)-aided knockdown of Ldeh at the final instar stage slightly impaired pupation and signifi cantly affected wing expansion. Around 20% of the Ldeh RNAi larvae remained as prepupae, completely wrapped in the old larval cuticles. These prepupae gradually darkened, dried and withered, and finally died. The remaining (about 80%) Ldeh hypomorphs became pupae and emerged as abnormal adults, bearing smaller and wrinkle elytra and hindwings. The adult tracheae in the Ldeh hypomorphs were full of liquid. In addition, the low pupation rate and high deformed adult proportion cannot be rescued by ingestion of either 20E or juvenile hormone. Thus, EH is critical for ecdysis and trachea clearance in L. decemlineata. The failure of trachea clearance may disenable air-swallowing during larva-pupa-adult transition and thus impacts wing growth and expansion.

Two Androstane Derivatives from the Cultures of Fungus Marasmiellus ramealis (Bull.) Singer

Yang, Ning-Ning,Ma, Qing-Yun,Huang, Sheng-Zhuo,Dai, Hao-Fu,Guo, Zhi-Kai,Yu, Zhi-Fang,Zhao, You-Xing Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.11

A new androstane derivative, $4{\beta}$-methyl-15-oxa-$14{\beta}$-androstane-7-ene-$4{\alpha}$-carboxylic acid (1) and a known one $4{\beta}$-methyl-15-oxa-$14{\beta}$-androstane-7-ene-$4{\alpha}$-hydroxyl (2) were isolated from the EtOAc extract of the cultures of the fungus Marasmiellus ramealis (Bull.) Singer. Their structures were elucidated on the basis of 1D and 2D NMR as well as MS spectroscopic data analysis. The inhibitory activity of two isolates against acetylcholinesterase (AChE) revealed that compound 1 exhibited definitely inhibitory activity.

Two New Phenolic Compounds from the Fruiting Bodies of Ganoderma tropicum

Hu, Li-Li,Ma, Qing-Yun,Huang, Sheng-Zhuo,Guo, Zhi-Kai,Guo, Jian-Chun,Dai, Hao-Fu,Zhao, You-Xing Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.3

Chemical investigation of the fruiting bodies of Ganoderma tropicum led to the isolation of two new phenolic compounds, ganodermatropins A (1) and B (2). Their structures were elucidated by spectroscopic techniques (MS, 1D and 2D NMR). Ganodermatropin A exhibited antimicrobial activity against Staphylococcus aureus.

Silencing downstream of receptor kinase gene (drk) impairs larval-pupal ecdysis in Leptinotarsa decemlineata (Say)

Pan Deng,Jun-Li Du,Li-Li Mu,Kai-Yun Fu,Wen-Chao Guo,Guo-Qing Li 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.1

In insects, an insulin-like peptide (ILP) triggers the formation of the insulin receptor (InR)/the insulin receptor substrate Chico complex. The complex then recruits downstream of receptor kinase (Drk) and phosphatidylinositol-3-kinase (PI3K) to initiate two signaling branches, i.e., Drk-mitogen-activated protein kinase (MAPK) and Pi3K-protein kinase B subdivisions. Previous findings reveal that RNA interference (RNAi) of LdILP2 or Ldchico, rather than Ldpi3k92E, impairs larval-pupal and pupal-adult molting in the Colorado potato beetle Leptinotarsa decemlineata. It is accordingly hypothesized that the Drk-MAPK branch regulates larval metamorphosis. In the present paper, we first found that silencing LdILP2, Ldchico or Ldpi3k92E did not decrease the expression level of Lddrk, indicating other receptor tyrosine kinases’ signaling except insulin pathway is not affected in the RNAi larvae. Moreover, two InRs and Torso were highly expressed in the final larval instars. Furthermore, RNAi of either Lddrk or Ldchico, or both of them equally affected larval-pupal and pupal-adult molts, and similarly repressed the expression of representative MAPK (Ldras and Ldraf), ecdysteroidogenesis (Ldphm and Ldsad), and 20E signaling (LdEcR, LdUSP, LdHR3 and LdE75) genes. 20E feeding by Lddrk RNAi larvae completely restored the reduced mRNA levels of LdEcR, LdHR3 and LdE75, but did not rescued the decreased Lddrk and LdUSP levels and the lowered pupation and emergence rates. Therefore, our findings suggest that the Drk-MAPK branch is involved in metamorphosis regulation in L. decemlineata.

Transcriptional response of Methoprene-tolerant (Met) gene to three insect growth disruptors in Leptinotarsa decemlineata (Say)

Qing-Wei Meng,Qing-Yu Xu,Pan Deng,Kai-Yun Fu,Wen-Chao Guo,Guo-Qing Li 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.2

Some insect growth disruptors (IGDs), such as pyriproxyfen and halofenozide, may be used to control Leptinotarsa decemlineata. However, their mechanism of action remains elusive. Methoprene-tolerant (Met) mediates juvenile hormone (JH) signal to control numerous essential physiological processes. In the present paper, we identified a Met gene (LdMet). LdMet protein was a typical basic helix-loop-helix/Per-Arnt-Sim (bHLHPAS) transcription factor with a bHLH domain, two PAS domains (PAS-A and PAS-B) and a region called PAS associated C terminal (PAC). Eight conserved amino acids critical for JH binding were located in PAS-B and PAC domains. The temporal expression pattern of LdMet was in accordance with the variation of circulating JH titers. Feeding of juvenoid methoprene or pyriproxyfen, or provide for JH dose-dependently stimulated the expression of LdMet. RNA interference-mediated knockdown of two JH degradation genes increased the transcription of LdMet, while silencing of a JH biosynthesis gene repressed the transcription. Conversely, ingestion of an ecdysteroid agonist halofenozide or 20-hydroxyecdysone (20E) reduced the mRNA levels of LdMet, in a dosedependent manner, whereas knockdown of either ecdysteroidogenesis or 20E signaling genes increased the mRNA accumulation. Providing that the expression of LdMet can be disturbed by methoprene, pyriproxyfen and halofenozide, LdMet may be a potential target of these IGDs in L. decemlineata larvae.

Disruption of ecdysis in Leptinotarsa decemlineata by knockdown of chitin deacetylase 1

Jian-Jian Wu,Li-Li Mu,Zhong-Chao Chen,Kai-Yun Fu,Wen-Chao Guo,Chao Li,Guo-Qing Li 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.2

Chitin deacetylases (CDAs) catalyze N-deacetylation of chitin, a crucial process for chitin modification. In the present paper, LdCDA1 was identified in Leptinotarsa decemlineata. It was copiously expressed in larval foregut, hindgut and epidermis. Just before the molt in the first, second and third larval instars, the mRNA levels of LdCDA1 were high. In the fourth (final)-instar larvae, a peak occurred 4 days after ecdysis. In vivo results revealed that LdCDA1 transcriptionally responded, positively and negatively respectively, to 20-hydroxyecdysone and juvenile hormone titers. Moreover, knockdown of LdCDA1 significantly reduced foliage consumption, lengthened developing period and prevented growth in the final instar larvae. Three distinct lethal phenotypes were noted in the LdCDA1 RNAi larvae. About 30% of the RNAi larvae became moribund and finally died; approximately 50% of deformed pupae died as pharate adults; and around 20% of LdCDA1 depleted pupae finally emerged as abnormal adults and eventually died within 1 week after emergence. Furthermore, chitin content was low and the mRNA levels of five chitin biosynthesis transcripts (LdUAP1, LdUAP2, LdChSAa, LdChSAb and LdChSB) were significantly declined in the LdCDA1 RNAi larvae. In addition, glucose, trehalose and glycogen contents were increased in the LdCDA1 depleted hypomorphs, along with highly expressed genes coding for trehalose and glycogen synthesis enzymes. The findings provide a compelling piece of evidence that CDA1 is critical for chitin deposition in L. decemlineata. Moreover, LdCDA1 may be a potential target for control of the larvae.