“…We also performed eosin staining and chitin staining in the midgut by injecting at 48 h and 72 h, respectively, and observed a significant decrease in chitin content in the midgut of the siCHSB group (Fig. 6c) [33]. Fig.…”
BackgroundThe growth and development of insects is strictly dependent on the precise regulation of chitin synthase (CHS), which is absent in vertebrates and plants. Therefore, CHS represents an attractive target for insecticides. At present, the research on the CHS gene in mosquitoes, especially its biological functions, remains limited.ResultsThe full-length cDNA of the chitin synthase B gene in Culex pipiens pallens (CpCHSB) was prepared and consists of 5158 nucleotides with an open reading frame (ORF) of 4722 nucleotides encoding a protein of 1573 amino acid residues. Among different tissues, CpCHSB gene is mainly expressed in the midgut tissue with the highest expression in adult mosquitoes. Knockdown of CpCHSB in the larval stage significantly lowered the chitin content (16.5%) decreased body size (reduced by 25.6% in the larval stage and by 25.6% in the adult stage), and diminished reproduction (20%). Injecting siCHSB into adult mosquito mainly decreased reproduction (27%).ConclusionsCpCHSB plays essential roles in growth and development, by severely reducing larval chitin content, midgut permeability, and reducing the number of female mosquito offspring. These results indicate that CHSB may serve as a potential novel target for exploring biosafe insecticides.
“…We also performed eosin staining and chitin staining in the midgut by injecting at 48 h and 72 h, respectively, and observed a significant decrease in chitin content in the midgut of the siCHSB group (Fig. 6c) [33]. Fig.…”
BackgroundThe growth and development of insects is strictly dependent on the precise regulation of chitin synthase (CHS), which is absent in vertebrates and plants. Therefore, CHS represents an attractive target for insecticides. At present, the research on the CHS gene in mosquitoes, especially its biological functions, remains limited.ResultsThe full-length cDNA of the chitin synthase B gene in Culex pipiens pallens (CpCHSB) was prepared and consists of 5158 nucleotides with an open reading frame (ORF) of 4722 nucleotides encoding a protein of 1573 amino acid residues. Among different tissues, CpCHSB gene is mainly expressed in the midgut tissue with the highest expression in adult mosquitoes. Knockdown of CpCHSB in the larval stage significantly lowered the chitin content (16.5%) decreased body size (reduced by 25.6% in the larval stage and by 25.6% in the adult stage), and diminished reproduction (20%). Injecting siCHSB into adult mosquito mainly decreased reproduction (27%).ConclusionsCpCHSB plays essential roles in growth and development, by severely reducing larval chitin content, midgut permeability, and reducing the number of female mosquito offspring. These results indicate that CHSB may serve as a potential novel target for exploring biosafe insecticides.
“…MLX56 was previously identified as an anti-herbivory defense protein of mulberry against lepidopteran herbivores [5,11]. Although the molecular mechanism of MLX56 has not been fully determined, the protein is known to cause abnormal swelling of the PM, probably through its binding to chitin of the membrane, and the swollen PM is suggested to function as a barrier to the digestive processes of insects.…”
Section: Discussionmentioning
confidence: 99%
“…A recent study showed that not only the MLX56 structure, but also the mode of the anti-insect action of MLX56 is unique [11]. Specifically, the study showed that the peritrophic membrane (PM; a thin membrane wrapping food material in the midgut of insects) in the midgut of the Eri silkworm, S. ricini, exhibited abnormal swelling when fed a diet containing MLX56.…”
Section: Introductionmentioning
confidence: 99%
“…Specifically, the study showed that the peritrophic membrane (PM; a thin membrane wrapping food material in the midgut of insects) in the midgut of the Eri silkworm, S. ricini, exhibited abnormal swelling when fed a diet containing MLX56. The findings suggested that the hevein domains of MLX56 bind to chitin containing PM, that the swelling of PM is induced by the swelling activity of the extensin domain, and that the swollen thick PM suppresses insect growth by functioning as a barrier against the movement of nutrient and digestive enzymes in the midgut of insects [11,12]. MLX56 may inhibit the growth of insects belonging to taxa other than Lepidopteran in similar ways, because insects belonging to most insect taxa have PM in their midgut.…”
Insect pests cause serious damage in crop production, and various attempts have been made to produce insect-resistance crops, including the expression of genes for proteins with anti-herbivory activity, such as BT toxins. However, the number of available genes with sufficient anti-herbivory activity is limited. MLX56 is an anti-herbivory protein isolated from the latex of mulberry plants, and has been shown to have a strong growth-suppressing activity against the larvae of a variety of lepidopteran species. As a model of herbivore-resistant plants, we produced transgenic tomato lines expressing the gene for MLX56. The transgenic tomato lines showed strong anti-herbivory activities against the larvae of the common cutworm, Spodoptera litura. Surprisingly, the transgenic tomato lines also exhibited strong activity against the attack of the western flower thrips, Frankliniera occidentalis. Further, growth of the hadda beetle, Henosepilachna vigintioctopunctata fed on leaves of transgenic tomato was significantly retarded. The levels of damage caused by both western flower thrips and hadda beetles were negligible in the high-MLX56-expressing tomato line. These results indicate that introduction of the gene for MLX56 into crops can enhance crop resistance against a wide range of pest insects, and that MLX56 can be utilized in developing pest-resistance GM crops.
“…The normal growth and development of insect is inseparable from the process of molting [11]. Many researchers investigated growth metabolic regulation and metabolism strategies in insects to identify novel targets for insect control [12][13][14][15][16][17].…”
Background: The pathogens transmitted by mosquitoes (Culex pipiens pallens) to humans and animals cause several emerging and resurgent infectious diseases. Increasing insecticide resistance requires rational action to control the target vector population. Chitin is indispensable for insect growth and development and absent from vertebrates and higher plants. Chitin synthase A (CHSA) represents a crucial enzyme in chitin synthesis; therefore, identifying and characterizing how CHSA determines the chitin content might help with novel vector control strategies. Results: The injection of small interfering RNA targeting CHSA (siCHSA) to knock down CHSA transcripts of in larval, pupal, and adult stages, showed different lethal phenotypes. In the larval and pupal stages, CHSA knockdown prevented larval molting, pupation, and adult eclosion, and affected the production of chitin and chitin degradation, which resulted in an ecdysis defect phenotype of mosquitoes. In the adult stage, it also affected the laminar organization of mesoderm and the formation of pseudo orthogonally large fibers of the endoderm. Conclusion: The present study provides a systematic and comprehensive description of the effects of CHSA on morphogenesis and metamorphosis. The results showed that CHSA not only affects chitin synthesis during molting, but also might be involved in chitin degradation. Our result further showed that CHSA is important for the structural integrity of the adult mosquito cuticle.
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