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1.
World J Clin Cases ; 11(17): 4194-4201, 2023 Jun 16.
Article in English | MEDLINE | ID: mdl-37388800

ABSTRACT

BACKGROUND: Hourglass-like constriction neuropathy is a rare neurological disorder. The main clinical manifestation is peripheral nerve injury with no apparent cause, and the pathomorphological change is an unexplained narrowing of the diseased nerve. The diagnosis and treatment of the disease are challenging and there is no accepted diagnostic or therapeutic approach. CASE SUMMARY: This report describes a rare hourglass constriction of the anterior interosseous nerve in the left forearm in a 47-year-old healthy male who was treated surgically and gradually recovered function over a 6-mo follow-up period. CONCLUSION: Hourglass-like constriction neuropathy is a rare disorder. With the development of medical technology, more examinations are now available for diagnosis. This case aims to highlight the rare manifestations of Hourglass-like constriction neuropathy and provides a reference for enriching the clinical diagnosis and treatment experience.

2.
Ecotoxicol Environ Saf ; 252: 114617, 2023 Mar 01.
Article in English | MEDLINE | ID: mdl-36758510

ABSTRACT

Bisphenol A (BPA) is putatively regarded as an environmental neurotoxicant found in everyday plastic products and materials, however, the possible neurobehavioral adverse consequences and molecular mechanisms in animals have not been clearly characterized. The nematode Caenorhabditis elegans has become a promising animal model for neurotoxicological researches. To investigate the dose-effect relationships of BPA-induced neurotoxicity effects, the locomotion behavior and developmental parameters of the nematode were determined after BPA exposure. The present data demonstrated that BPA caused neurobehavioral toxicities, including head thrashes and body bends inhibition. In addition, when C. elegans was exposed to BPA at a concentration higher than 2 µM, growth and survival rate were decreased. The serotonergic, dopaminergic and GABAergic neurons were damaged by BPA. Furthermore, lower levels of mRNA expression related to dopamine, serotonin and GABA were detected in the worms exposed to 50 µM BPA. Increased SOD-3 expression might be adaptive response to BPA exposure. Moreover, oxidative damage triggered by BPA was manifested by changes in GST-4 expression, accompany with abnormity of ATP synthesis, but not nuclear localization of DAF-16/FOXO. Finally, we showed that epigallocatechin-3-gallate partially rescued BPA-induced reactive oxygen species (ROS) production and neurobehavioral toxicity. Altogether, the neurobehavioral and developmental toxicity of BPA may be induced by neurotransmission abnormity and oxidative damage. The present data imply that oxidative stress is linked to neuronal damage and neurobehavioral harm resulting from developmental BPA exposure.


Subject(s)
Caenorhabditis elegans Proteins , Caenorhabditis elegans , Animals , Caenorhabditis elegans/metabolism , Caenorhabditis elegans Proteins/genetics , Caenorhabditis elegans Proteins/metabolism , Oxidative Stress , Benzhydryl Compounds/metabolism , Reactive Oxygen Species/metabolism , Neurotransmitter Agents/metabolism
3.
World J Clin Cases ; 10(28): 10227-10235, 2022 Oct 06.
Article in English | MEDLINE | ID: mdl-36246824

ABSTRACT

BACKGROUND: Myeloid sarcoma (MS) is relatively rare, occurring mainly in the skin and lymph nodes, and MS invasion of the ulnar nerve is particularly unusual. The main aim of this article is to present a case of MS invading the brachial plexus, causing ulnar nerve entrapment syndrome, and to further clinical understanding of the possibility of MS invasion of peripheral nerves. CASE SUMMARY: We present the case of a 46-year-old man with a 13-year history of well-treated acute nonlymphocytic leukaemia who was admitted to the hospital after presenting with numbness and pain in his left little finger. The initial diagnosis was considered a simple case of nerve entrapment disease, with magnetic resonance imaging showing slightly abnormal left brachial plexus nerve alignment with local thickening, entrapment, and high signal on compression lipid images. Due to the severity of the ulnar nerve compression, we surgically investigated and cleared the entrapment and nerve tissue hyperplasia; however, subsequent pathological biopsy results revealed evidence of MS. The patient had significant relief from his neurological symptoms, with no postoperative complications, and was referred to the haemato-oncology department for further consultation about the primary disease. This is the first report of safe treatment of ulnar nerve entrapment from MS. It is intended to inform hand surgeons that nerve entrapment may be associated with extramedullary MS, as a rare presenting feature of the disease. CONCLUSION: MS invasion of the brachial plexus and surrounding tissues of the upper arm, resulting in ulnar nerve entrapment and degeneration with significant neurological pain and numbness in the little finger, is uncommon. Surgical treatment significantly relieved the patient's nerve entrapment symptoms and prevented further neurological impairment. This case is reported to highlight the rare presenting features of MS.

4.
Nat Commun ; 13(1): 5619, 2022 09 24.
Article in English | MEDLINE | ID: mdl-36153338

ABSTRACT

The silkworm Bombyx mori is an important economic insect for producing silk, the "queen of fabrics". The currently available genomes limit the understanding of its genetic diversity and the discovery of valuable alleles for breeding. Here, we deeply re-sequence 1,078 silkworms and assemble long-read genomes for 545 representatives. We construct a high-resolution pan-genome dataset representing almost the entire genomic content in the silkworm. We find that the silkworm population harbors a high density of genomic variants and identify 7308 new genes, 4260 (22%) core genes, and 3,432,266 non-redundant structure variations (SVs). We reveal hundreds of genes and SVs that may contribute to the artificial selection (domestication and breeding) of silkworm. Further, we focus on four genes responsible, respectively, for two economic (silk yield and silk fineness) and two ecologically adaptive traits (egg diapause and aposematic coloration). Taken together, our population-scale genomic resources will promote functional genomics studies and breeding improvement for silkworm.


Subject(s)
Bombyx , Diapause , Animals , Bombyx/genetics , Domestication , Genomics , Silk/genetics
5.
Pest Manag Sci ; 78(12): 5334-5346, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36039742

ABSTRACT

BACKGROUND: Lepidoptera is one of the largest orders of insects, some of which are major pests of crops and forests. The cuticles of lepidopteran pests play important roles in defense against insecticides and pathogens, and are indispensable for constructing and maintaining extracellular structures and locomotion during their life cycle. Lepidopteran-specific cuticular proteins could be potential targets for lepidopteran pest control. But information on this is limited. Our research aimed to screen the lepidopteran-specific cuticular proteins using the lepidopteran model, the silkworm, to explore the molecular mechanism underlying the involvement of cuticular proteins in body shape construction. RESULTS: Positional cloning showed that BmLSPMP-like, a gene encoding a lepidopteran-specific peritrophic matrix protein (PMP) like protein which includes a peritrophin A-type chitin-binding domain (CBM_14), is responsible for the stick (sk) mutation. BmLSPMP-like is an evolutionarily conserved gene that exhibits synteny in Lepidoptera and underwent purifying selection during evolution. Expression profiles demonstrated that BmLSPMP-like is expressed in chitin-forming tissues, testis and ovary, and accumulates in the cuticle. BmLSPMP-like knockout, generated with CRISPR/Cas9, resulted in a stick-like larval body shape phenotype. Over-expression of BmLSPMP-like in the sk mutant rescued its abnormal body shape. The results showed that BmLSPMP-like may be involved in assemblage in the larval cuticle. CONCLUSION: Our results suggested that the dysfunction of BmLSPMP-like may result in a stick body shape phenotype in silkworm, through the regulation of the arrangement of the chitinous laminae and cuticle thickness. Our study provides new evidence of the effects of LSPMP-likes on lepidopteran body shape formation, metamorphosis and mortality, which could be an eco-friendly target for lepidopteran pest management. © 2022 Society of Chemical Industry.


Subject(s)
Bombyx , Animals , Female , Male , Bombyx/metabolism , Insect Proteins/genetics , Somatotypes , Chitin , Larva/genetics , Mutation
6.
Insect Sci ; 29(1): 65-77, 2022 Feb.
Article in English | MEDLINE | ID: mdl-33822467

ABSTRACT

The development of insect appendages requires the expression of multiple genes in a strict spatial and temporal order. The odd-skipped family genes are vital transcriptional factors involved in embryonic development. The development and morphogenesis of the insect wing requires multiple transcription factors to regulate the expression of wing patterning genes at the transcriptional level. However, the function of odd-related genes in insect wing morphogenesis and development during postembryonic stages is unclear. We focused on the roles of the sister of odd and bowl (sob) gene, a member of odd-skipped family genes, during the wing morphopoiesis in Bombyx mori using the clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9 system and in Tribolium castaneum by RNA interference. The results showed that the wings were significantly smaller and degenerated, and wing veins were indistinct in the sob gene loss-of-function group in both B. mori and T. castaneum. Quantitative real-time polymerase chain reaction revealed that the Tcsob gene regulated the expression of wing development genes, such as the cht 7 and the vg gene. The findings suggest the importance of sob gene in insect wing morphology formation during postembryonic stages.


Subject(s)
Bombyx , Tribolium , Animals , Bombyx/genetics , Insect Proteins/genetics , Morphogenesis , Tribolium/genetics , Wings, Animal
8.
J Proteomics ; 238: 104155, 2021 04 30.
Article in English | MEDLINE | ID: mdl-33610826

ABSTRACT

Wing discs of Bombyx mori (B. mori) are transformed into wings during metamorphosis via dramatic morphological and structural changes. Mutations in genes related to the wings cause the adults to have altered wing shapes or abnormal wing colour. At present, there are more than 20 wing mutants recorded in the silkworm. However, the key factors that influence B. mori wing development are still unclear. Here, we used the strains +Wes/+Wes and Wes/+Wes that are typical for the normal wing and shriveled wing phenotypes, respectively, to identify differentially expressed proteins by label-free data-independent acquisition (DIA). Ten enriched GO terms and 9 KEGG pathways were identified based on the 3993 proteins in the wings. Among the identified and quantified proteins, 370 differentially expressed proteins (DEPs) were detected (P-value <0.01, |log2FC| > 0.58). Mapping of the DEPs to the reference canonical pathways in KEGG showed that the top 20% of the pathways were related to fatty acid, cutin, suberin and wax biosynthesis, protein processing in endoplasmic reticulum, protein export, etc. Of the 370 DEPs, 238 were down-regulated, and 132 were up-regulated of Wes/+Wes compared with +Wes/+Wes. Numerous cuticular proteins were down-regulated, and fatty metabolism enzymes were up-regulated, in Wes/+Wes compared with +Wes/+Wes. SIGNIFICANCE: The comparative analysis of proteomes suggested that cuticular proteins and fatty metabolism enzymes are the main abnormally expressed proteins in the pupal wings of Wes/+Wes, leading to curly and shrunken wings after moth transformation. Our results also identify the substances affecting the development of silkworm wings from the perspective of proteins. The information from this study is important for further research on the molecular mechanisms of wing development in lepidopteran insects, and these differentially expressed genes may be targets for Lepidoptera pest control.


Subject(s)
Bombyx , Animals , Bombyx/genetics , Insect Proteins/genetics , Lipids , Proteome , Wings, Animal
9.
Insect Sci ; 28(5): 1290-1299, 2021 Oct.
Article in English | MEDLINE | ID: mdl-32918398

ABSTRACT

The coloration and hatchability of insect eggs can affect individual and population survival. However, few genetic loci have been documented to affect both traits, and the genes involved in regulating these two traits are unclear. The silkworm recessive mutant rel shows both red egg color and embryo mortality. We studied the molecular basis of the rel phenotype formation. Through genetic analysis, gene screening and sequencing, we found that two closely linked genes, BGIBMGA003497 (Bm-re) and BGIBMGA003697 (BmSema1a), control egg color and embryo mortality, respectively. Six base pairs of the Bm-re gene are deleted in its open reading frame, and BmSema1a is expressed at abnormally low levels in mutant rel . BmSema1a gene function verification was performed using RNA interference and clustered randomly interspersed palindromic repeats (CRISPR)/CRISPR-associate protein 9. Deficiency of the BmSema1a gene can cause the death of silkworm embryos. This study revealed the molecular basis of silkworm rel mutant formation and indicated that the Sema1a gene is essential for insect embryo development.


Subject(s)
Bombyx , Insect Proteins , Ovum/pathology , Semaphorins/genetics , Animals , Bombyx/embryology , Bombyx/genetics , Embryo, Nonmammalian , Embryonic Development/genetics , Insect Proteins/genetics , Phenotype , Pigmentation
10.
PLoS Genet ; 16(9): e1009004, 2020 09.
Article in English | MEDLINE | ID: mdl-32986696

ABSTRACT

Many insects spin cocoons to protect the pupae from unfavorable environments and predators. After emerging from the pupa, the moths must escape from the sealed cocoons. Previous works identified cocoonase as the active enzyme loosening the cocoon to form an escape-hatch. Here, using bioinformatics tools, we show that cocoonase is specific to Lepidoptera and that it probably existed before the occurrence of lepidopteran insects spinning cocoons. Despite differences in cocooning behavior, we further show that cocoonase evolved by purification selection in Lepidoptera and that the selection is more intense in lepidopteran insects spinning sealed cocoons. Experimentally, we applied gene editing techniques to the silkworm Bombyx mori, which spins a dense and sealed cocoon, as a model of lepidopteran insects spinning sealed cocoons. We knocked out cocoonase using the CRISPR/Cas9 system. The adults of homozygous knock-out mutants were completely formed and viable but stayed trapped and died naturally in the cocoon. This is the first experimental and phenotypic evidence that cocoonase is the determining factor for breaking the cocoon. This work led to a novel silkworm strain yielding permanently intact cocoons and provides a new strategy for controlling the pests that form cocoons.


Subject(s)
Bombyx/enzymology , Life Cycle Stages/physiology , Animals , Animals, Genetically Modified , Bombyx/genetics , CRISPR-Cas Systems , Gene Knockout Techniques , Homozygote , Mutation , Phylogeny , Selection, Genetic , Species Specificity
11.
PLoS Genet ; 16(7): e1008907, 2020 07.
Article in English | MEDLINE | ID: mdl-32667927

ABSTRACT

Holometabolous insects have distinct larval, pupal, and adult stages. The pupal stage is typically immobile and can be subject to predation, but cocoon offers pupal protection for many insect species. The cocoon provides a space in which the pupa to adult metamorphosis occurs. It also protects the pupa from weather, predators and parasitoids. Silk protein is a precursor of the silk used in cocoon construction. We used the silkworm as a model species to identify genes affecting silk protein synthesis and cocoon construction. We used quantitative genetic analysis to demonstrate that ß-1,4-N-acetylglucosaminidase 1 (BmGlcNase1) is associated with synthesis of sericin, the main composite of cocoon. BmGlcNase1 has an expression pattern coupled with silk gland development and cocoon shell weight (CSW) variation, and CSW is an index of the ability to synthesize silk protein. Up-regulated expression of BmGlcNase1 increased sericin content by 13.9% and 22.5% while down-regulation reduced sericin content by 41.2% and 27.3% in the cocoons of females and males, respectively. Genomic sequencing revealed that sequence variation upstream of the BmGlcNase1 transcriptional start site (TSS) is associated with the expression of BmGlcNase1 and CSW. Selective pressure analysis showed that GlcNase1 was differentially selected in insects with and without cocoons (ω1 = 0.044 vs. ω2 = 0.154). This indicates that this gene has a conserved function in the cocooning process of insects. BmGlcNase1 appears to be involved in sericin synthesis and silkworm cocooning.


Subject(s)
Acetylglucosaminidase/genetics , Bombyx/genetics , Breeding , Domestication , Animals , Bombyx/physiology , Female , Gene Expression Regulation/genetics , Larva/genetics , Larva/growth & development , Male , Protein Biosynthesis/genetics , Silk/genetics
12.
Cell Cycle ; 18(18): 2293-2306, 2019 09.
Article in English | MEDLINE | ID: mdl-31322047

ABSTRACT

Cytosine arabinoside (Ara-c) is a pyrimidine anti-metabolite that is capable of interfering with cellular proliferation by inhibiting DNA synthesis. Each inhibitor of cyclin-dependent kinase 4 (INK4) family member has the ability to bind to cyclin-dependent kinase 4 (CDK4) and inhibit the formation of the cell cycle-dependent CDK4/cyclin D1 complex, subsequently leading to cell cycle arrest in the G1/S phase. In this study, the expression of INK4 family genes in kidney cancer and the impact of these genes on patient prognosis were examined. Additionally, the effects of INK4 family genes and Ara-c on cell proliferation and tumor formation and development were examined. Finally, a potential association between Ara-c-induced cell cycle arrest and INK4-associated gene expression was evaluated. An upregulation of INK4 family genes was found to be positively correlated with the prognosis of patients with kidney cancer. Both the INK4 family genes and Ara-c were shown to induce cell cycle arrest and inhibit tumor formation and development. Moreover, Ara-c-induced cell cycle arrest was found to be associated with an Ara-c-induced upregulation of INK4 family gene expression, which ultimately inhibited the formation of the CDK4/cyclin D1 complex. These findings suggested that an upregulation of INK4 family genes has a positive effect on kidney cancer prognosis and can inhibit the formation and development of tumors. Moreover, Ara-c was shown to promote the upregulation of INK4 family genes, at the same time, Ara-c could directly regulate the cell cycle-dependent genes CDK4 and cyclin D1 (CCND1), independent of the INK4 family genes.


Subject(s)
Carcinoma, Renal Cell/metabolism , Cyclin D1/metabolism , Cyclin-Dependent Kinase 4/metabolism , Cyclin-Dependent Kinase Inhibitor Proteins/genetics , Cytarabine/pharmacology , G1 Phase Cell Cycle Checkpoints/drug effects , Kidney Neoplasms/metabolism , S Phase Cell Cycle Checkpoints/drug effects , Up-Regulation/drug effects , Animals , Carcinoma, Renal Cell/pathology , Cell Line, Tumor , Cell Proliferation/drug effects , Cyclin D1/antagonists & inhibitors , Cyclin D1/genetics , Cyclin-Dependent Kinase 4/antagonists & inhibitors , Cyclin-Dependent Kinase 4/genetics , Cyclin-Dependent Kinase Inhibitor Proteins/metabolism , Gene Expression Regulation, Neoplastic/drug effects , Heterografts , Humans , Kidney Neoplasms/pathology , Mice , Mice, Nude , Prognosis , Transfection
13.
Sci Rep ; 7(1): 17985, 2017 12 21.
Article in English | MEDLINE | ID: mdl-29269837

ABSTRACT

Mechanisms that regulate silk protein synthesis provide the basis for silkworm variety breeding and silk gland bioreactor optimization. Here, using the pooling sequencing-based methodology, we deciphered the genetic basis for the varied silk production in different silkworm strains. We identified 8 SNPs, with 6 on chromosome 11 and 1 each on chromosomes 22 and 23, that were linked with silk production. After conducting an association analysis between gene expression pattern, silk gland development and cocoon shell weight (CSW), BMGN011620 was found to be regulating silk production. BMGN011620 encodes the 60S ribosomal protein, L18, which is an indispensable component of the 60S ribosomal subunit; therefore we named it BmRPL18. Moreover, the clustering of linked SNPs on chromosome 11 and the analysis of differentially expressed genes reported in previous Omics studies indicated that the genes regulating silk protein synthesis may exhibit a clustering distribution in the silkworm genome. These results collectively advance our understanding of the regulation of silk production, including the role of ribosomal proteins and the clustered distribution of genes involved in silk protein synthesis.


Subject(s)
Bombyx/genetics , Genes, Insect/genetics , Quantitative Trait Loci/genetics , Animals , Chromosomes, Insect/genetics , Gene Expression Regulation , Genetic Linkage , Polymorphism, Single Nucleotide/genetics , Ribosomes/genetics , Sequence Analysis, DNA , Silk/genetics
14.
Genetics ; 207(3): 1053-1066, 2017 11.
Article in English | MEDLINE | ID: mdl-28923848

ABSTRACT

The genetic basis of body shape and coloration patterns on caterpillars is often assumed to be regulated separately, but it is possible that common molecules affect both types of trait simultaneously. Here we examine the genetic basis of a spontaneous cuticle defect in silkworm, where larvae exhibit a bamboo-like body shape and decreased pigmentation. We performed linkage mapping and mutation screening to determine the gene product that affects body shape and coloration simultaneously. In these mutant larvae we identified a null mutation in BmorCPH24, a gene encoding a cuticular protein with low complexity sequence. Spatiotemporal expression analyses showed that BmorCPH24 is expressed in the larval epidermis postecdysis. RNAi-mediated knockdown and CRISPR/Cas9-mediated knockout of BmorCPH24 produced the abnormal body shape and the inhibited pigment typical of the mutant phenotype. In addition, our results showed that BmorCPH24 may be involved in the synthesis of endocuticle and its disruption-induced apoptosis of epidermal cells that accompanied the reduced expression of R&R-type larval cuticle protein genes and pigmentation gene Wnt1 Strikingly, BmorCPH24, a fast-evolving gene, has evolved a new function responsible for the assembly of silkworm larval cuticle and has evolved to be an indispensable factor maintaining the larval body shape and its coloration pattern. This is the first study to identify a molecule whose pleiotropic function affects the development of body shape and color patterns in insect larvae.


Subject(s)
Body Size , Bombyx/genetics , Insect Proteins/genetics , Skin Pigmentation , Animals , Bombyx/anatomy & histology , Bombyx/metabolism , Insect Proteins/metabolism , Larva/anatomy & histology , Larva/metabolism , Loss of Function Mutation , Wnt1 Protein/genetics , Wnt1 Protein/metabolism
15.
Sci Rep ; 6: 18956, 2016 Jan 07.
Article in English | MEDLINE | ID: mdl-26738847

ABSTRACT

The morphological diversity of insects is important for their survival; in essence, it results from the differential expression of genes during development of the insect body. The silkworm apodal (ap) mutant has degraded thoracic legs making crawling and eating difficult and the female is sterile, which is an ideal subject for studying the molecular mechanisms of morphogenesis. Here, we confirmed that the infertility of ap female moths is a result of the degradation of the bursa copulatrix. Positional cloning of ap locus and expression analyses reveal that the Bombyx mori sister of odd and bowl (Bmsob) gene is a strong candidate for the ap mutant. The expression of Bmsob is down-regulated, while the corresponding Hox genes are up-regulated in the ap mutant compared to the wild type. Analyses with the dual luciferase assay present a declined activity of the Bmsob promoter in the ap mutant. Furthermore, we demonstrate that Bmsob can inhibit Hox gene expression directly and by suppressing the expression of other genes, including the BmDsp gene. The results of this study are an important contribution to our understanding of the diversification of insect body plan.


Subject(s)
Bombyx/genetics , Genes, Insect , Animals , Chromosome Mapping , Female , Gene Expression , Gene Expression Regulation, Developmental , Genetic Association Studies , Genetic Linkage , Infertility, Female , Insect Proteins/genetics , Insect Proteins/metabolism , Male , Mutation , Promoter Regions, Genetic
16.
Funct Integr Genomics ; 15(5): 511-22, 2015 Sep.
Article in English | MEDLINE | ID: mdl-25893708

ABSTRACT

The forkhead box (Fox) transcription factor family has a characteristic of forkhead domain, a winged DNA-binding domain. The Fox genes have been classified into 23 subfamilies, designated FoxA to FoxS, of which the FoxR and FoxS subfamilies are specific to vertebrates. In this review, using whole-genome scanning, we identified 17 distinct Fox genes distributed on 13 chromosomes of the silkworm, Bombyx mori. A phylogenetic tree showed that the silkworm Fox genes could be classified into 13 subfamilies. The FoxK subfamily is specifically absent from the silkworm, although it is present in other lepidopteran insects, including Danaus plexippus and Heliconius melpomene. Microarray data revealed that the Fox genes have distinct expression patterns in the tissues on day 3 of the 5th instar larva. A Gene Ontology analysis suggested that the Fox genes have roles in cellular components, molecular functions, and biological processes, except in pore complex biogenesis. An analysis of the selective pressure on the proteins indicated that most of the amino acid sites in the Fox proteins are undergoing strong purifying selection. Here, we summarize the general characteristics of the Fox genes in the silkworm, which should support further functional studies of the silkworm Fox proteins.


Subject(s)
Bombyx/genetics , Forkhead Transcription Factors/genetics , Insect Proteins/genetics , Amino Acid Sequence , Animals , Chromosome Mapping , Chromosomes, Insect/genetics , Gene Expression , Gene Ontology , Genome, Insect , Humans , Molecular Sequence Data , Phylogeny , Selection, Genetic
17.
Genetics ; 196(4): 1103-15, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24514903

ABSTRACT

Cuticular proteins (CPs) are crucial components of the insect cuticle. Although numerous genes encoding cuticular proteins have been identified in known insect genomes to date, their functions in maintaining insect body shape and adaptability remain largely unknown. In the current study, positional cloning led to the identification of a gene encoding an RR1-type cuticular protein, BmorCPR2, highly expressed in larval chitin-rich tissues and at the mulberry leaf-eating stages, which is responsible for the silkworm stony mutant. In the Dazao-stony strain, the BmorCPR2 allele is a deletion mutation with significantly lower expression, compared to the wild-type Dazao strain. Dysfunctional BmorCPR2 in the stony mutant lost chitin binding ability, leading to reduced chitin content in larval cuticle, limitation of cuticle extension, abatement of cuticle tensile properties, and aberrant ratio between internodes and intersegmental folds. These variations induce a significant decrease in cuticle capacity to hold the growing internal organs in the larval development process, resulting in whole-body stiffness, tightness, and hardness, bulging intersegmental folds, and serious defects in larval adaptability. To our knowledge, this is the first study to report the corresponding phenotype of stony in insects caused by mutation of RR1-type cuticular protein. Our findings collectively shed light on the specific role of cuticular proteins in maintaining normal larval body shape and will aid in the development of pest control strategies for the management of Lepidoptera.


Subject(s)
Bombyx/anatomy & histology , Chitin/metabolism , Insect Proteins/genetics , Insect Proteins/metabolism , Adaptation, Biological , Animals , Bombyx/genetics , Bombyx/growth & development , Bombyx/physiology , Cloning, Molecular , Genetic Loci , Genome, Insect , Larva/anatomy & histology , Larva/genetics , Mutation , Organ Specificity , Phenotype
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