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14 pages, 5010 KiB

Open AccessArticle

Sterol Regulation of Development and 20-Hydroxyecdysone Biosynthetic and Signaling Genes in Drosophila melanogaster

by Di Wen, Zhi Chen, Jiamin Wen and Qiangqiang Jia

Cells 2023, 12(13), 1739; https://doi.org/10.3390/cells12131739 - 28 Jun 2023

Cited by 2 | Viewed by 1385

Abstract

Ecdysteroids are crucial in regulating the growth and development of insects. In the fruit fly Drosophila melanogaster, both C₂₇ and C₂₈ ecdysteroids have been identified. While the biosynthetic pathway of the C₂₇ ecdysteroid 20-hydroxyecdysone (20E) from cholesterol is relatively [...] Read more.

Ecdysteroids are crucial in regulating the growth and development of insects. In the fruit fly Drosophila melanogaster, both C₂₇ and C₂₈ ecdysteroids have been identified. While the biosynthetic pathway of the C₂₇ ecdysteroid 20-hydroxyecdysone (20E) from cholesterol is relatively well understood, the biosynthetic pathway of C₂₈ ecdysteroids from C₂₈ or C₂₉ dietary sterols remains unknown. In this study, we found that different dietary sterols (including the C₂₇ sterols cholesterol and 7-dehydrocholesterol, the C₂₈ sterols brassicasterol, campesterol, and ergosterol, and the C₂₉ sterols β-sitosterol, α-spinasterol, and stigmasterol) differentially affected the expression of 20E biosynthetic genes to varying degrees, but similarly activated 20E primary response gene expression in D. melanogaster Kc cells. We also found that a single dietary sterol was sufficient to support D. melanogaster growth and development. Furthermore, the expression levels of some 20E biosynthetic genes were significantly altered, whereas the expression of 20E signaling primary response genes remained unaffected when flies were reared on lipid-depleted diets supplemented with single sterol types. Overall, our study provided preliminary clues to suggest that the same enzymatic system responsible for the classical C₂₇ ecdysteroid 20E biosynthetic pathway also participated in the conversion of C₂₈ and C₂₉ dietary sterols into C₂₈ ecdysteroids. Full article

(This article belongs to the Special Issue Cellular Events in Insect Development, Immunity, and Reproduction)

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13 pages, 8251 KiB

Open AccessArticle

Functional Analysis of Pheromone Biosynthesis Activating Neuropeptide Receptor Isoforms in Maruca vitrata

by Wook Hyun Cha, Boyun Kim and Dae-Weon Lee

Cells 2023, 12(10), 1410; https://doi.org/10.3390/cells12101410 - 17 May 2023

Viewed by 1341

Abstract

Insect sex pheromones are volatile chemicals that induce mating behavior between conspecific individuals. In moths, sex pheromone biosynthesis is initiated when pheromone biosynthesis-activating neuropeptide (PBAN) synthesized in the suboesophageal ganglion binds to its receptor on the epithelial cell membrane of the pheromone gland. [...] Read more.

Insect sex pheromones are volatile chemicals that induce mating behavior between conspecific individuals. In moths, sex pheromone biosynthesis is initiated when pheromone biosynthesis-activating neuropeptide (PBAN) synthesized in the suboesophageal ganglion binds to its receptor on the epithelial cell membrane of the pheromone gland. To investigate the function of PBAN receptor (PBANR), we identified two PBANR isoforms, MviPBANR-B and MviPBANR-C, in the pheromone glands of Maruca vitrata. These two genes belong to G protein-coupled receptors (GPCRs) and have differences in the C-terminus but share a 7-transmembrane region and GPCR family 1 signature. These isoforms were expressed in all developmental stages and adult tissues. MviPBANR-C had the highest expression level in pheromone glands among the examined tissues. Through in vitro heterologous expression in HeLa cell lines, only MviPBANR-C-transfected cells responded to MviPBAN (≥5 µM MviPBAN), inducing Ca²⁺ influx. Sex pheromone production and mating behavior were investigated using gas chromatography and a bioassay after MviPBANR-C suppression by RNA interference, which resulted in the major sex pheromone component, E10E12-16:Ald, being quantitatively reduced compared to the control, thereby decreasing the mating rate. Our findings indicate that MviPBANR-C is involved in the signal transduction of sex pheromone biosynthesis in M. vitrata and that the C-terminal tail plays an important role in its function. Full article

(This article belongs to the Special Issue Cellular Events in Insect Development, Immunity, and Reproduction)

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16 pages, 3358 KiB

Open AccessArticle

Oxalic Acid Inhibits Feeding Behavior of the Brown Planthopper via Binding to Gustatory Receptor Gr23a

by Kui Kang, Mengyi Zhang, Lei Yue, Weiwen Chen, Yangshuo Dai, Kai Lin, Kai Liu, Jun Lv, Zhanwen Guan, Shi Xiao and Wenqing Zhang

Cells 2023, 12(5), 771; https://doi.org/10.3390/cells12050771 - 28 Feb 2023

Cited by 4 | Viewed by 1717

Abstract

Plants produce diverse secondary compounds as natural protection against microbial and insect attack. Most of these compounds, including bitters and acids, are sensed by insect gustatory receptors (Grs). Although some organic acids are attractive at low or moderate levels, most acidic compounds are [...] Read more.

Plants produce diverse secondary compounds as natural protection against microbial and insect attack. Most of these compounds, including bitters and acids, are sensed by insect gustatory receptors (Grs). Although some organic acids are attractive at low or moderate levels, most acidic compounds are potentially toxic to insects and repress food consumption at high concentrations. At present, the majority of the reported sour receptors function in appetitive behaviors rather than aversive taste responses. Here, using two different heterologous expression systems, the insect Sf9 cell line and the mammalian HEK293T cell line, we started from crude extracts of rice (Oryza sativa) and successfully identified oxalic acid (OA) as a ligand of NlGr23a, a Gr in the brown planthopper Nilaparvata lugens that feeds solely on rice. The antifeedant effect of OA on the brown planthopper was dose dependent, and NlGr23a mediated the repulsive responses to OA in both rice plants and artificial diets. To our knowledge, OA is the first identified ligand of Grs starting from plant crude extracts. These findings on rice–planthopper interactions will be of broad interest for pest control in agriculture and also for better understanding of how insects select host plants. Full article

(This article belongs to the Special Issue Cellular Events in Insect Development, Immunity, and Reproduction)

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17 pages, 8446 KiB

Open AccessArticle

Tandem Multimerization Can Enhance the Structural Homogeneity and Antifungal Activity of the Silkworm Protease Inhibitor BmSPI39

by Youshan Li, Yuan Wang, Rui Zhu, Xi Yang, Meng Wei, Zhaofeng Zhang, Changqing Chen and Ping Zhao

Cells 2023, 12(5), 693; https://doi.org/10.3390/cells12050693 - 22 Feb 2023

Viewed by 1333

Abstract

Previous studies have shown that BmSPI39, a serine protease inhibitor of silkworm, can inhibit virulence-related proteases and the conidial germination of insect pathogenic fungi, thereby enhancing the antifungal capacity of Bombyx mori. The recombinant BmSPI39 expressed in Escherichia coli has poor structural [...] Read more.

Previous studies have shown that BmSPI39, a serine protease inhibitor of silkworm, can inhibit virulence-related proteases and the conidial germination of insect pathogenic fungi, thereby enhancing the antifungal capacity of Bombyx mori. The recombinant BmSPI39 expressed in Escherichia coli has poor structural homogeneity and is prone to spontaneous multimerization, which greatly limits its development and application. To date, the effect of multimerization on the inhibitory activity and antifungal ability of BmSPI39 remains unknown. It is urgent to explore whether a BmSPI39 tandem multimer with better structural homogeneity, higher activity and a stronger antifungal ability can be obtained by protein engineering. In this study, the expression vectors of BmSPI39 homotype tandem multimers were constructed using the isocaudomer method, and the recombinant proteins of tandem multimers were obtained by prokaryotic expression. The effects of BmSPI39 multimerization on its inhibitory activity and antifungal ability were investigated by protease inhibition and fungal growth inhibition experiments. In-gel activity staining and protease inhibition assays showed that tandem multimerization could not only greatly improve the structural homogeneity of the BmSPI39 protein, but also significantly increase its inhibitory activity against subtilisin and proteinase K. The results of conidial germination assays showed that tandem multimerization could effectively enhance the inhibitory ability of BmSPI39 on the conidial germination of Beauveria bassiana. A fungal growth inhibition assay showed that BmSPI39 tandem multimers had certain inhibitory effects on both Saccharomyces cerevisiae and Candida albicans. The inhibitory ability of BmSPI39 against these the above two fungi could be enhanced by tandem multimerization. In conclusion, this study successfully achieved the soluble expression of tandem multimers of the silkworm protease inhibitor BmSPI39 in E. coli and confirmed that tandem multimerization can improve the structural homogeneity and antifungal ability of BmSPI39. This study will not only help to deepen our understanding of the action mechanism of BmSPI39, but also provide an important theoretical basis and new strategy for cultivating antifungal transgenic silkworms. It will also promote its exogenous production and development and application in the medical field. Full article

(This article belongs to the Special Issue Cellular Events in Insect Development, Immunity, and Reproduction)

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12 pages, 3597 KiB

Open AccessArticle

Diallyl Trisulfide, a Biologically Active Component of Garlic Essential Oil, Decreases Male Fertility in Sitotroga cerealella by Impairing Dimorphic Spermatogenesis, Sperm Motility and Lipid Homeostasis

by Sakhawat Shah, Karam Khamis Elgizawy, Chun-Mei Shi, Hucheng Yao, Wen-Han Yan, Yu Li, Xiao-Ping Wang, Gang Wu and Feng-Lian Yang

Cells 2023, 12(4), 669; https://doi.org/10.3390/cells12040669 - 20 Feb 2023

Cited by 4 | Viewed by 1718

Abstract

Diallyl trisulfide (DAT) is a biologically active component of garlic essential oil and exhibits multi-targeted activity against many organisms. The current study tested the capacity of DAT to decrease the male fertility of Sitotroga cerealella. The effects on testis morphology, sperm number, [...] Read more.

Diallyl trisulfide (DAT) is a biologically active component of garlic essential oil and exhibits multi-targeted activity against many organisms. The current study tested the capacity of DAT to decrease the male fertility of Sitotroga cerealella. The effects on testis morphology, sperm number, motility, and lipid homeostasis were observed in adult males fumigated with DAT at a dose of 0.01 μL/L in air. The results indicated that the DAT significantly decreased the dimorphic sperm number. Meanwhile, the ultrastructural analysis of the sperm showed that the DAT caused malformed and aberrant structures of mitochondrial derivatives of dimorphic sperm. Additionally, the lipid homeostasis and ATP contents in the male adults were significantly decreased after treatment. Moreover, the total sperm motility was reduced, while the wave-propagation velocity, amplitude, frequency, and wavelength were significantly decreased compared with the controls. Overall, this study reported, for the first time, that DAT impairs energy metabolism, inhibits dimorphic spermatogenesis, and decreases sperm motility, while these abnormalities in sperm lead to adult-male infertility. Full article

(This article belongs to the Special Issue Cellular Events in Insect Development, Immunity, and Reproduction)

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18 pages, 3675 KiB

Open AccessArticle

Functional Analysis of a Multiple-Domain CTL15 in the Innate Immunity, Eclosion, and Reproduction of Tribolium castaneum

by Suisui Wang, Huayi Ai, Yonglei Zhang, Jingxiu Bi, Han Gao, Peng Chen and Bin Li

Cells 2023, 12(4), 608; https://doi.org/10.3390/cells12040608 - 13 Feb 2023

Cited by 3 | Viewed by 1652

Abstract

C-type lectin X (CTL-X) plays critical roles in immune defense, cell adhesion, and developmental regulation. Here, a transmembrane CTL-X of Tribolium castaneum, TcCTL15, with multiple domains was characterized. It was highly expressed in the early and late pupae and early adults and [...] Read more.

C-type lectin X (CTL-X) plays critical roles in immune defense, cell adhesion, and developmental regulation. Here, a transmembrane CTL-X of Tribolium castaneum, TcCTL15, with multiple domains was characterized. It was highly expressed in the early and late pupae and early adults and was distributed in all examined tissues. In addition, its expression levels were significantly induced after being challenged with pathogen-associated molecular patterns (PAMPs) and bacteria. In vitro, the recombinant TcCTL15 could recognize bacteria through binding PAMPs and exhibit agglutinating activity against a narrow range of bacteria in the presence of Ca²⁺. RNAi-mediated TcCTL15-knockdown-larvae infected with Escherichia coli and Staphylococcus aureus showed less survival, had activated immune signaling pathways, and induced the expression of antimicrobial peptide genes. Moreover, silencing TcCTL15 caused eclosion defects by impairing ecdysone and crustacean cardioactive peptide receptors (CCAPRs). Suppression of TcCTL15 in female adults led to defects in ovary development and fecundity, accompanied by concomitant reductions in the mRNA levels of vitellogenin (TcVg) and farnesol dehydrogenase (TcFDH). These findings imply that TcCTL15 has extensive functions in developmental regulation and antibacterial immunity. Uncovering the function of TcCTL15 will enrich the understanding of CTL-X in invertebrates. Its multiple biological functions endow the potential to be an attractive target for pest control. Full article

(This article belongs to the Special Issue Cellular Events in Insect Development, Immunity, and Reproduction)

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12 pages, 2475 KiB

Open AccessArticle

The LIM Domain Protein BmFHL2 Inhibits Egg Production in Female Silkworm, Bombyx mori

by Qian Yuan, Xiaoning Sun, Riming Lu, Zhigang Qu, Xueyan Ding, Taiming Dai, Jianfeng Qiu, Yumei Tan, Ruihong Zhu, Zhonghua Pan, Shiqing Xu and Yanghu Sima

Cells 2023, 12(3), 452; https://doi.org/10.3390/cells12030452 - 31 Jan 2023

Cited by 1 | Viewed by 1690

Abstract

The female Bombyx mori accumulates a large amount of egg proteins, mainly Vg and 30K, during egg formation to provide nutrition for embryo development. The synthesis and transport of Vg have been extensively studied, particularly the regulation of Vg transcription induced by 20E; however, [...] Read more.

The female Bombyx mori accumulates a large amount of egg proteins, mainly Vg and 30K, during egg formation to provide nutrition for embryo development. The synthesis and transport of Vg have been extensively studied, particularly the regulation of Vg transcription induced by 20E; however, the mechanism of 30K protein synthesis is poorly studied. As a model organism of the order Lepidoptera, B. mori has high reproduction potential. In the present study, we found that the FHL2 homologous gene (BmFhl2) in B. mori is involved in inhibiting female egg formation by influencing the synthesis of 30K protein. Interference of BmFhl2 expression in silkworm females increased 30K protein synthesis, accelerated ovarian development, and significantly increased the number of eggs produced and laid; however, the 20E pathway was inhibited. The transcription levels of Vg and 30Kc19 were significantly downregulated following BmFhl2 overexpression in the silkworm ovarian cell line BmN. The Co-IP assay showed that the potential binding protein of BmFHL2 included three types of 30K proteins (30Kc12, 30Kc19, and 30Kc21). These results indicate that BmFHL2 participates in egg formation by affecting 30K protein in female B. mori. Full article

(This article belongs to the Special Issue Cellular Events in Insect Development, Immunity, and Reproduction)

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19 pages, 5986 KiB

Open AccessArticle

Aspirin Inhibition of Prostaglandin Synthesis Impairs Mosquito Egg Development

by Duyeol Choi, Md. Abdullah Al Baki, Shabbir Ahmed and Yonggyun Kim

Cells 2022, 11(24), 4092; https://doi.org/10.3390/cells11244092 - 16 Dec 2022

Cited by 3 | Viewed by 2422

Abstract

Several endocrine signals mediate mosquito egg development, including 20-hydroxyecdysone (20E). This study reports on prostaglandin E₂ (PGE₂) as an additional, but core, mediator of oogenesis in a human disease-vectoring mosquito, Aedes albopictus. Injection of aspirin (an inhibitor of cyclooxygenase [...] Read more.

Several endocrine signals mediate mosquito egg development, including 20-hydroxyecdysone (20E). This study reports on prostaglandin E₂ (PGE₂) as an additional, but core, mediator of oogenesis in a human disease-vectoring mosquito, Aedes albopictus. Injection of aspirin (an inhibitor of cyclooxygenase (COX)) after blood-feeding (BF) inhibited oogenesis by preventing nurse cell dumping into a growing oocyte. The inhibitory effect was rescued by PGE₂ addition. PGE₂ was found to be rich in nurse cells and follicular epithelium after BF. RNA interference (RNAi) treatments of PG biosynthetic genes, including PLA₂ and two COX-like peroxidases, prevented egg development. Interestingly, 20E treatment significantly increased the expressions of PG biosynthetic genes, while the RNAi of Shade (which is a 20E biosynthetic gene) expression prevented inducible expressions after BF. Furthermore, RNAi treatments of PGE₂ receptor genes suppressed egg production, even under PGE₂. These results suggest that a signaling pathway of BF-20E-PGE₂ is required for early vitellogenesis in the mosquito. Full article

(This article belongs to the Special Issue Cellular Events in Insect Development, Immunity, and Reproduction)

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Review

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11 pages, 446 KiB

Open AccessReview

Beyond Cellular Immunity: On the Biological Significance of Insect Hemocytes

by David Stanley, Eric Haas and Yonggyun Kim

Cells 2023, 12(4), 599; https://doi.org/10.3390/cells12040599 - 12 Feb 2023

Cited by 11 | Viewed by 2368

Abstract

Insect immunity is assorted into humoral and cellular immune reactions. Humoral reactions involve the regulated production of anti-microbial peptides, which directly kill microbial invaders at the membrane and intracellular levels. In cellular immune reactions, millions of hemocytes are mobilized to sites of infection [...] Read more.

Insect immunity is assorted into humoral and cellular immune reactions. Humoral reactions involve the regulated production of anti-microbial peptides, which directly kill microbial invaders at the membrane and intracellular levels. In cellular immune reactions, millions of hemocytes are mobilized to sites of infection and replaced by hematopoiesis at a high biological cost after the immune defense. Here, we considered that the high biological costs of maintaining and replacing hemocytes would be a better investment if hemocytes carried out meaningful biological actions unrelated to cellular immunity. This idea allows us to treat a set of 10 hemocyte actions that are not directly involved in immunity, some of which, so far, are known only in Drosophila melanogaster. These include (1) their actions in molting and development, (2) in surviving severe hypoxia, (3) producing phenoloxidase precursor and its actions beyond immunity, (4) producing vitellogenin in a leafhopper, (5) recognition and responses to cancer in Drosophila, (6) non-immune actions in Drosophila, (7) clearing apoptotic cells during development of the central nervous system, (8) developing hematopoietic niches in Drosophila, (9) synthesis and transport of a lipoprotein, and (10) hemocyte roles in iron transport. We propose that the biological significance of hemocytes extends considerably beyond immunity. Full article

(This article belongs to the Special Issue Cellular Events in Insect Development, Immunity, and Reproduction)

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