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1.
Sci Rep ; 14(1): 17879, 2024 Aug 02.
Article in English | MEDLINE | ID: mdl-39095549

ABSTRACT

Odours used by insects for foraging and mating are carried by the air. Insects induce airflows around them by flapping their wings, and the distribution of these airflows may strongly influence odour source localisation. The flightless silkworm moth, Bombyx mori, has been a prominent insect model for olfactory research. However, although there have been numerous studies on antenna morphology and its fluid dynamics, neurophysiology, and localisation algorithms, the airflow manipulation of the B. mori by fanning has not been thoroughly investigated. In this study, we performed computational fluid dynamics (CFD) analyses of flapping B. mori to analyse this mechanism in depth. A three-dimensional simulation using reconstructed wing kinematics was used to investigate the effects of B. mori fanning on locomotion and pheromone capture. The fanning of the B. mori was found to generate an aerodynamic force on the scale of its weight through an aerodynamic mechanism similar to that of flying insects. Our simulations further indicate that the B. mori guides particles from its anterior direction within the ~ 60° horizontally by wing fanning. Hence, if it detects pheromones during fanning, the pheromone can be concluded to originate from the direction the head is pointing. The anisotropy in the sampling volume enables the B. mori to orient to the pheromone plume direction. These results provide new insights into insect behaviour and offer design guidelines for robots for odour source localisation.


Subject(s)
Bombyx , Flight, Animal , Pheromones , Wings, Animal , Animals , Wings, Animal/physiology , Bombyx/physiology , Bombyx/chemistry , Pheromones/metabolism , Flight, Animal/physiology , Computer Simulation , Smell/physiology , Biomechanical Phenomena , Odorants/analysis , Hydrodynamics
2.
Commun Biol ; 7(1): 786, 2024 Jun 29.
Article in English | MEDLINE | ID: mdl-38951579

ABSTRACT

Fibroins' transition from liquid to solid is fundamental to spinning and underpins the impressive native properties of silk. Herein, we establish a fibroin heavy chain fold for the Silk-I polymorph, which could be relevant for other similar proteins, and explains mechanistically the liquid-to-solid transition of this silk, driven by pH reduction and flow stress. Combining spectroscopy and modelling we propose that the liquid Silk-I fibroin heavy chain (FibH) from the silkworm, Bombyx mori, adopts a newly reported ß-solenoid structure. Similarly, using rheology we propose that FibH N-terminal domain (NTD) templates reversible higher-order oligomerization driven by pH reduction. Our integrated approach bridges the gap in understanding FibH structure and provides insight into the spatial and temporal hierarchical self-assembly across length scales. Our findings elucidate the complex rheological behaviour of Silk-I, solutions and gels, and the observed liquid crystalline textures within the silk gland. We also find that the NTD undergoes hydrolysis during standard regeneration, explaining key differences between native and regenerated silk feedstocks. In general, in this study we emphasize the unique characteristics of native and native-like silks, offering a fresh perspective on our fundamental understanding of silk-fibre production and applications.


Subject(s)
Bombyx , Fibroins , Bombyx/metabolism , Bombyx/chemistry , Animals , Fibroins/chemistry , Fibroins/metabolism , Rheology , Silk/chemistry , Silk/metabolism , Hydrogen-Ion Concentration
3.
J Chromatogr A ; 1730: 465168, 2024 Aug 16.
Article in English | MEDLINE | ID: mdl-39018739

ABSTRACT

In recent years, some insects have become foods due to their high nutritional value. In order to solve the problem of the lack of quality control methods for insect foods, this study proposes a comprehensive control model using silkworm chrysalis (SC) as an example. Firstly, five-wavelength mean fusion fingerprints (FWMFF) and UV quantum fingerprints of 21 batches of SC were established. And the 21 batches of SC were classified into different grades from different perspectives by using the comprehensive linear quantified fingerprint method (CLQFM) as a quality evaluation method for qualitative and quantitative analysis. Secondly, this paper fully considered the issue of the reliability of fingerprint evaluation, which guaranteed the accuracy of the evaluation results. On this basis, the antioxidant capacity of the samples was used in vitro 1,1-Diphenyl-2-picrylhydrazylradical (DPPH) scavenging assay using IC50. The relationship between fingerprints and antioxidant activity was also discussed. Finally, the content of endogenous neurotransmitter (ACh) in SC determined by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in the range of 0.25-2.11µg/g. Overall, the present study proposes a comprehensive quality control strategy for functional foods based on the quality assessment of SC.


Subject(s)
Acetylcholine , Antioxidants , Bombyx , Quality Control , Tandem Mass Spectrometry , Animals , Antioxidants/analysis , Antioxidants/chemistry , Bombyx/chemistry , Chromatography, High Pressure Liquid/methods , Tandem Mass Spectrometry/methods , Acetylcholine/analysis , Acetylcholine/chemistry , Reproducibility of Results
4.
Int J Mol Sci ; 25(11)2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38892315

ABSTRACT

The traditional production mode of the sericulture industry is no longer suitable for the development requirements of modern agriculture; to facilitate the sustainable development of the sericulture industry, factory all-age artificial diet feeding came into being. Understanding the structural characteristics and properties of silk fibers obtained from factory all-age artificial diet feeding is an important prerequisite for application in the fields of textiles, clothing, biomedicine, and others. However, there have been no reports so far. In this paper, by feeding silkworms with factory all-age artificial diets (AD group) and mulberry leaves (ML group), silk fibers were obtained via two different feeding methods. The structure, mechanical properties, hygroscopic properties, and degradation properties were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Structurally, no new functional groups appeared in the AD group. Compared with the ML group, the structure of the two groups was similar, and there was no significant difference in mechanical properties and moisture absorption. The structure of degummed silk fibers is dominated by crystalline regions, but α-chymotrypsin hydrolyzes the amorphous regions of silk proteins, so that after 28 d of degradation, the weight loss of both is very small. This provides further justification for the feasibility of factory all-age artificial diets for silkworms.


Subject(s)
Bombyx , Silk , Animals , Silk/chemistry , Bombyx/chemistry , X-Ray Diffraction , Spectroscopy, Fourier Transform Infrared , Thermogravimetry , Morus/chemistry
5.
PeerJ ; 12: e17490, 2024.
Article in English | MEDLINE | ID: mdl-38903886

ABSTRACT

Background: Pathogenic bacteria are the cause of most skin diseases, but issues such as resistance and environmental degradation drive the need to research alternative treatments. It is reported that silk cocoon extract possesses antioxidant properties. During silk processing, the degumming of silk cocoons creates a byproduct that contains natural active substances. These substances were found to have inhibitory effects on bacterial growth, DNA synthesis, the pathogenesis of hemolysis, and biofilm formation. Thus, silk cocoon extracts can be used in therapeutic applications for the prevention and treatment of skin pathogenic bacterial infections. Methods: The extract of silk cocoons with pupae (SCP) and silk cocoons without pupae (SCWP) were obtained by boiling with distilled water for 9 h and 12 h, and were compared to silkworm pupae (SP) extract that was boiled for 1 h. The active compounds in the extracts, including gallic acid and quercetin, were determined using high-performance liquid chromatography (HPLC). Furthermore, the total phenolic and flavonoid content in the extracts were investigated using the Folin-Ciocalteu method and the aluminum chloride colorimetric method, respectively. To assess antioxidant activity, the extracts were evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Additionally, the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of silk extracts and phytochemical compounds were determined against skin pathogenic bacteria. This study assessed the effects of the extracts and phytochemical compounds on growth inhibition, biofilm formation, hemolysis protection, and DNA synthesis of bacteria. Results: The HPLC characterization of the silk extracts showed gallic acid levels to be the highest, especially in SCP (8.638-31.605 mg/g extract) and SP (64.530 mg/g extract); whereas quercetin compound was only detected in SCWP (0.021-0.031 mg/g extract). The total phenolics and flavonoids in silk extracts exhibited antioxidant and antimicrobial activity. Additionally, SCP at 9 h and 12 h revealed the highest anti-bacterial activity, with the lowest MIC and MBC of 50-100 mg/mL against skin pathogenic bacteria including Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Cutibacterium acnes and Pseudomonas aeruginosa. Hence, SCP extract and non-sericin compounds containing gallic acid and quercetin exhibited the strongest inhibition of both growth and DNA synthesis on skin pathogenic bacteria. The suppression of bacterial pathogenesis, including preformed and matured biofilms, and hemolysis activity, were also revealed in SCP extract and non-sericin compounds. The results show that the byproduct of silk processing can serve as an alternative source of natural phenolic and flavonoid antioxidants that can be used in therapeutic applications for the prevention and treatment of pathogenic bacterial skin infections.


Subject(s)
Anti-Bacterial Agents , Antioxidants , Bombyx , Silk , Animals , Bombyx/chemistry , Antioxidants/pharmacology , Antioxidants/chemistry , Silk/chemistry , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/isolation & purification , Biofilms/drug effects , Pupa/drug effects , Free Radicals/metabolism , Microbial Sensitivity Tests , Hemolysis/drug effects
6.
J Mater Chem B ; 12(26): 6351-6370, 2024 Jul 03.
Article in English | MEDLINE | ID: mdl-38864220

ABSTRACT

Surface wrinkling provides an approach to modify the surfaces of biomedical devices to better mimic features of the extracellular matrix and guide cell attachment, proliferation, and differentiation. Biopolymer wrinkling on active materials holds promise but is poorly explored. Here we report a mechanically actuated assembly process to generate uniaxial micro-and nanosized silk fibroin (SF) wrinkles on a thermo-responsive shape-memory polymer (SMP) substrate, with wrinkling demonstrated under both dry and hydrated (cell compatible) conditions. By systematically investigating the influence of SMP programmed strain magnitude, film thickness, and aqueous media on wrinkle stability and morphology, we reveal how to control the wrinkle sizes on the micron and sub-micron length scale. Furthermore, as a parameter fundamental to SMPs, we demonstrate that the temperature during the recovery process can also affect the wrinkle characteristics and the secondary structures in the silk network. We find that with increasing SMP programmed strain magnitude, silk wrinkled topographies with increasing wavelengths and amplitudes are achieved. Furthermore, silk wrinkling is found to increase ß-sheet content, with spectroscopic analysis suggesting that the effect may be due primarily to tensile (e.g., Poisson effect and high-curvature wrinkle) loading modes in the SF, despite the compressive bulk deformation (uniaxial contraction) used to produce wrinkles. Silk wrinkles fabricated from sufficiently thick films (roughly 250 nm) persist after 24 h in cell culture medium. Using a fibroblast cell line, analysis of cellular response to the wrinkled topographies reveals high viability and attachment. These findings demonstrate use of wrinkled SF films under physiologically relevant conditions and suggest the potential for biopolymer wrinkles on biomaterials surfaces to find application in cell mechanobiology, wound healing, and tissue engineering.


Subject(s)
Fibroins , Fibroins/chemistry , Animals , Biopolymers/chemistry , Mice , Biocompatible Materials/chemistry , Biocompatible Materials/pharmacology , Protein Structure, Secondary , Bombyx/chemistry , Surface Properties , Silk/chemistry , Fibroblasts/cytology , Smart Materials/chemistry
7.
ACS Biomater Sci Eng ; 10(7): 4552-4561, 2024 Jul 08.
Article in English | MEDLINE | ID: mdl-38922676

ABSTRACT

Silkworms have provided valuable byproducts (spanning from high-quality textiles to health supplements) to humans for millennia. Despite their importance in sericultural economy and biotechnology, manifold possibilities inherent in the myriad natural or artificially generated silk varieties have been underestimated. In this paper, we report that the Yeonnokjam silk strain, which shows light-green color, contains quercetin fluorochrome (QueF) in sericin, and QueF can be used as a fluorescence dye with a large Stokes shift and high sensitivity to environmental temperature and pH, thus functioning as an environmental sensing material. A Stokes shift exceeding 180 nm, a quantum efficiency of 1.28%, and a rapid fluorescence decay of 0.67 ns are obtained, which are influenced by solvent polarities. Moreover, QueF can be used as a UV blocker as well, and its low cytotoxicity and biocompatibility further suggest promising prospects for diverse application in cosmetics and medical materials in the future.


Subject(s)
Bombyx , Fluorescent Dyes , Sericins , Silk , Fluorescent Dyes/chemistry , Animals , Silk/chemistry , Bombyx/chemistry , Humans , Sericins/chemistry , Quercetin/chemistry , Hydrogen-Ion Concentration , Temperature , Biocompatible Materials/chemistry
8.
Int J Biol Macromol ; 274(Pt 1): 132770, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38834121

ABSTRACT

Degumming is the most critical step for the silk textile industry and the process of silk-based advanced materials. However, current common degumming techniques are largely limited because of insufficient efficiency, obvious hydrolysis damage and difficulty in long-term storage. Here, deep eutectic solvent (DES) constituted of choline chloride (ChCl) and urea was explored to Bombyx mori silk fibers degumming without combining any further treatment. Compared to traditional alkali methods, DES could quickly remove about 26.5 % of sericin in just 40 min, and its degumming efficiency hardly decrease after seven cycles. Owing to the "tear off" degumming mechanism of DES molecules with "large volume", the resulted sericin has a large molecular weight of 250 kDa. In addition, because of antibacterial activity and stabilizing effect, no aggregation occurred and strong bacterial growth inhibition was triggered in the obtained sericin/DES solution. Furthermore, thanks to the good retention of crystalline region and slight swelling of amorphous area, the sericin-free fibroin showed significant increases in moisture absorption and dye uptake, while maintaining good mechanical properties. Featured with high efficiency, reduction in water pollution, easy storage of sericin as well as high quality fibers, this approach is of great potential for silk wet processing.


Subject(s)
Bombyx , Deep Eutectic Solvents , Sericins , Silk , Animals , Sericins/chemistry , Deep Eutectic Solvents/chemistry , Bombyx/chemistry , Silk/chemistry , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Choline/chemistry , Molecular Weight , Urea/chemistry
9.
Int J Biol Macromol ; 272(Pt 1): 132702, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38810851

ABSTRACT

Fibroin is a structural protein derived from silk cocoons, which may be used in a variety of biomedical applications due to its high biocompatibility and controllable material properties. Conversely, fibroin solution is inherently unstable in solution, which limits its potential utility. Fibroin hydrolysates possess enhanced aqueous solubility and stability, with known anti-inflammatory bioactivity. Here, silk-derived protein (SDP) was produced through controlled time, temperature, and pressure conditions to generate a novel and reproducible hydrolysate population. Both regenerated fibroin and SDP solution stability were characterized for MWD, amino acid content, solubility, viscosity, surface interaction, secondary structure formation, and in vitro assessment of NF-kB pathway activity. Mechanistic studies indicate that hydrolysis processing is required to enhance material stability by abolishing fibroin's ability to self-associate. In vitro assays using HCLE cells indicate SDP has dose dependent potency for inhibiting NF-kB driven gene expression of TNF-α and MMP-9. Collectively, the results support SDP's use as an anti-inflammatory wetting agent compatible with a wide range of both biomedical and industrial applications. Furthermore, the conditions used to generate SDP hydrolysates are readily accessible, produce a highly consistent material from batch-to-batch, and permit widespread investigation of this novel population for these purposes.


Subject(s)
Fibroins , NF-kappa B , Fibroins/chemistry , NF-kappa B/metabolism , Hydrolysis , Kinetics , Animals , Humans , Gels/chemistry , Solubility , Viscosity , Bombyx/chemistry , Bombyx/metabolism , Matrix Metalloproteinase 9/metabolism , Tumor Necrosis Factor-alpha/metabolism
10.
Poult Sci ; 103(7): 103812, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38735098

ABSTRACT

The present experiment was conducted to test the effect of a 4% defatted silkworm (Bombyx mori) pupae meal (SWM) incorporation into chickens' diets at different growth phases on meat quality characteristics and sensory traits. Ninety ROSS 308 day-old male broiler chickens were randomly assigned to 3 dietary groups, with 5 replicated pens/diet: the first group received a control (C) diet throughout the growing period of 42 d, the second group received a diet with 4% SWM (SWM1) during the starter phase (1-10 d) and the C diet up to slaughter, whereas the third group was fed the C diet during the starter phase and 4% SWM during the grower and finisher phases (SWM2). Diets were isonitrogenous and isoenergy, and birds had free access to feed and water throughout the experimental trial. At 42 d of age, 15 chickens/treatment were slaughtered at a commercial abattoir. Fatty acid (FA) and amino acid (AA) profiles and contents of meat, as well as its oxidative status, were determined in both breast and leg meat cuts. Also, a descriptive sensory analysis was performed on breast meat by trained panelists. Results highlighted that the SWM2 treatment increased the n-3 proportion and content in both breast and leg meat, thereby improving the omega-6/omega-3 (n-6/n-3) ratio in both cuts (P < 0.001). However, the dietary treatment had no significant effect on the oxidative status of either breast or leg meat (P > 0.05). The SWM had a limited impact on overall sensory traits of breast meat, but it contributed to improve meat tenderness in SWM-fed chickens (P < 0.01). Furthermore, SWM1 meat exhibited higher juiciness (P < 0.05) and off flavor intensity (P < 0.05) compared to the control meat. Overall, the present experiment indicated that defatted SWM holds promise as an alternative ingredient in chicken rations, ensuring satisfactory meat quality. Furthermore, administering SWM during the grower-finisher phase demonstrated beneficial effects on meat healthiness, ultimately enhancing n-3 fatty acids content and reducing the n-6/n-3 ratio.


Subject(s)
Animal Feed , Bombyx , Chickens , Diet , Meat , Animals , Chickens/physiology , Chickens/growth & development , Animal Feed/analysis , Diet/veterinary , Male , Meat/analysis , Bombyx/chemistry , Random Allocation , Pupa/growth & development , Animal Nutritional Physiological Phenomena , Fatty Acids/analysis , Fatty Acids/metabolism
11.
Ultrason Sonochem ; 107: 106927, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38820934

ABSTRACT

A novel technique was proposed for processing silkworm pupae by combining plasma- activated water (PAW) with ultrasound (US). The microbial diversity and quality characteristics of the silkworm pupae were also evaluated. The results of the microbial diversity analysis indicated that PAW combined with US treatment significantly reduced the relative abundance of Streptococcaceae, Leuconostocaceae, and Acetobacteraceae from 32%, 18% and 16% to 27%, 11% and 11%, respectively. Microstructural analysis demonstrated that the collapse of the internal structure of chitin in silkworm pupae facilitated the release of nutrients and flavour compounds including fatty acids, water-soluble proteins (WSP), amino acids, phenolics, and volatile compounds. Furthermore, the increase in antioxidant capacity and the decrease in catalase activity and malondialdehyde content confirmed the mechanism of quality change. These findings provide new insights into the possible mechanism of PAW combined with US to improve the quality of edible insects.


Subject(s)
Bombyx , Pupa , Water , Animals , Pupa/microbiology , Water/chemistry , Bombyx/chemistry , Ultrasonic Waves , Chemical Phenomena , Antioxidants/chemistry , Antioxidants/pharmacology , Biodiversity
12.
Molecules ; 29(9)2024 Apr 23.
Article in English | MEDLINE | ID: mdl-38731405

ABSTRACT

Chitin, a ubiquitous biopolymer, holds paramount scientific and economic significance. Historically, it has been primarily isolated from marine crustaceans. However, the surge in demand for chitin and the burgeoning interest in biopolymers have necessitated the exploration of alternative sources. Among these methods, the mulberry silkworm (Bombyx mori) has emerged as a particularly intriguing prospect. To isolate chitin from Bombyx mori, a chemical extraction methodology was employed. This process involved a series of meticulously orchestrated steps, including Folch extraction, demineralization, deproteinization, and decolorization. The resultant chitin was subjected to comprehensive analysis utilizing techniques such as attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), 13C nuclear magnetic resonance (NMR) spectroscopy, and wide-angle X-ray scattering (WAXS). The obtained results allow us to conclude that the Bombyx mori represents an attractive alternative source of α-chitin.


Subject(s)
Bombyx , Chitin , Bombyx/chemistry , Animals , Chitin/chemistry , Chitin/isolation & purification , Spectroscopy, Fourier Transform Infrared , X-Ray Diffraction , Magnetic Resonance Spectroscopy , Morus/chemistry
13.
Biomed Chromatogr ; 38(8): e5906, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38807034

ABSTRACT

The application of traditional Chinese medicine dispensing granules is becoming increasingly prevalent. However, the consistency of dispensing granules with traditional decoction remains controversial. In this study, the consistency of peptide composition and pharmacodynamics between dispensing granules and traditional decoction of Bombyx batryticatus (BB) were assessed. A peptidomics method based on LC-tandem mass spectrometry technology was used to evaluate peptide composition similarity between BB traditional decoction and dispensing granules. The results revealed notable differences in peptide sequences between the two dosage forms, with only 8.55% of peptides shared between them. To evaluate the potential pharmacodynamic effects of the two dosage forms on epilepsy, virtual screening was used to identify potential active peptides, including blood-brain barrier permeability, toxicity prediction, and molecular docking. BB traditional decoction demonstrated a higher number and greater abundance of potential active peptides than BB dispensing granules, suggesting that BB traditional decoction may have a more favorable effect in treating epilepsy compared with BB dispensing granules. Moreover, molecular docking and molecular dynamics simulation studies confirmed the mechanism of action of active peptides to γ-aminobutyric acid transporter 1 (GAT-1). This study provides a scientific basis for the evaluation of quality consistency between BB traditional decoction and dispensing granules.


Subject(s)
Bombyx , Molecular Docking Simulation , Tandem Mass Spectrometry , Animals , Tandem Mass Spectrometry/methods , Bombyx/chemistry , Medicine, Chinese Traditional , Peptides/chemistry , Peptides/analysis , Proteomics/methods , Drugs, Chinese Herbal/chemistry , Drugs, Chinese Herbal/analysis , Drugs, Chinese Herbal/pharmacology , Computer Simulation , Chromatography, Liquid/methods , Molecular Dynamics Simulation
14.
Int J Biol Macromol ; 269(Pt 1): 131748, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38670194

ABSTRACT

Bio-based shape memory materials have attracted wide attention due to their biocompatibility, degradability and safety. However, designing and manufacturing wearable bio-based shape memory films with excellent flexibility and toughness is still a challenge. In this work, silk fibroin substrate with a ß-sheet structure was combined with a tri-block shape memory copolymer to prepare a transparent composited shape memory film. The silk fibroin-based film showed a dual-responsive shape memory function, which can respond to both temperature and water stimuli. This film has a sensitive water-responsive shape memory, which starts deforming after exposure to water for 3 s and fully recovers in 30 s. In addition, the composite film shows highly stretchable (>300 %) and could maintain its high tensile properties after 5 cycles of regeneration. The films also exhibited rapid degradation ability. This study provides new insights for the design of dual-responsive shape memory materials by combining biocompatible matrix and multi-block SMP to simultaneously enhance the mechanical properties, which can be used for intelligent packaging, medical supplies, soft actuators and wearable devices.


Subject(s)
Biocompatible Materials , Fibroins , Fibroins/chemistry , Biocompatible Materials/chemistry , Smart Materials/chemistry , Tensile Strength , Temperature , Water/chemistry , Bombyx/chemistry
15.
Nature ; 629(8010): 228-234, 2024 May.
Article in English | MEDLINE | ID: mdl-38447670

ABSTRACT

Animals crave sugars because of their energy potential and the pleasurable sensation of tasting sweetness. Yet all sugars are not metabolically equivalent, requiring mechanisms to detect and differentiate between chemically similar sweet substances. Insects use a family of ionotropic gustatory receptors to discriminate sugars1, each of which is selectively activated by specific sweet molecules2-6. Here, to gain insight into the molecular basis of sugar selectivity, we determined structures of Gr9, a gustatory receptor from the silkworm Bombyx mori (BmGr9), in the absence and presence of its sole activating ligand, D-fructose. These structures, along with structure-guided mutagenesis and functional assays, illustrate how D-fructose is enveloped by a ligand-binding pocket that precisely matches the overall shape and pattern of chemical groups in D-fructose. However, our computational docking and experimental binding assays revealed that other sugars also bind BmGr9, yet they are unable to activate the receptor. We determined the structure of BmGr9 in complex with one such non-activating sugar, L-sorbose. Although both sugars bind a similar position, only D-fructose is capable of engaging a bridge of two conserved aromatic residues that connects the pocket to the pore helix, inducing a conformational change that allows the ion-conducting pore to open. Thus, chemical specificity does not depend solely on the selectivity of the ligand-binding pocket, but it is an emergent property arising from a combination of receptor-ligand interactions and allosteric coupling. Our results support a model whereby coarse receptor tuning is derived from the size and chemical characteristics of the pocket, whereas fine-tuning of receptor activation is achieved through the selective engagement of an allosteric pathway that regulates ion conduction.


Subject(s)
Bombyx , Insect Proteins , Receptors, G-Protein-Coupled , Sugars , Taste , Animals , Allosteric Regulation , Binding Sites , Bombyx/metabolism , Bombyx/chemistry , Cryoelectron Microscopy , Fructose/metabolism , Fructose/chemistry , Insect Proteins/chemistry , Insect Proteins/genetics , Insect Proteins/metabolism , Insect Proteins/ultrastructure , Ligands , Models, Molecular , Molecular Docking Simulation , Protein Binding , Receptors, G-Protein-Coupled/chemistry , Receptors, G-Protein-Coupled/genetics , Receptors, G-Protein-Coupled/metabolism , Receptors, G-Protein-Coupled/ultrastructure , Sorbose/chemistry , Sorbose/metabolism , Substrate Specificity , Sugars/metabolism , Sugars/chemistry , Taste/physiology
16.
Int J Biol Macromol ; 264(Pt 2): 130687, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38462112

ABSTRACT

Silk fibroin derived from silkworm cocoons exhibits excellent mechanical properties, good biocompatibility, and low immunogenicity. Previous studies showed that silk fibroin had an inhibitory effect on cells, suppressing proliferation and inducing apoptosis. However, the source of the toxicity and the mechanism of apoptosis induction are still unclear. In this study, we hypothesized that the toxicity of silk fibroin might originate from the crystalline region of the heavy chain of silk fibroin. We then verified the hypothesis and the specific induction mechanism. A target peptide segment was obtained from α-chymotrypsin. The potentially toxic mixture of silk fibroin peptides (SFPs) was separated by ion exchange, and the toxicity was tested by an MTT assay. The results showed that SFPs obtained after 4 h of enzymatic hydrolysis had significant cytotoxicity, and SFPs with isoelectric points of 4.0-6.8 (SFPα II) had a significant inhibitory effect on cell growth. LC-MS/MS analysis showed that SFPα II contained a large number of glycine-rich and alanine-rich repetitive sequence polypeptides from the heavy-chain crystallization region. A series of experiments showed that SFPα II mediated cell death through the apoptotic pathway by decreasing the expression of Bcl-2 protein and increasing the expression of Bax protein. SFPα II mainly affected the p53 pathway and the AMPK signaling pathway in HepG2 cells. SFPα II may indirectly increase the expression of Cers2 by inhibiting the phosphorylation of EGFR, which activated apoptotic signaling in the cellular mitochondrial pathway and inhibited the Akt/NF-κB pathway by increasing the expression of PPP2R2A.


Subject(s)
Bombyx , Fibroins , Animals , Fibroins/pharmacology , Fibroins/chemistry , Chromatography, Liquid , Tandem Mass Spectrometry , Peptides/pharmacology , Peptides/chemistry , Bombyx/chemistry , Apoptosis , Silk/chemistry
17.
J Sci Food Agric ; 104(9): 5407-5418, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38345737

ABSTRACT

BACKGROUND: Silkworm (Bombyx moil L.) Pupa protein (SPP) is a high-quality insect protein and is considered a sustainable alternative source for traditional animal food protein. However, the utilization of SPP is limited because of its low solubility and emulsifying ability. In the present study, the synergistic effect of hydration and pulsed ultrasound on the physicochemical properties of SPP and SPP-stabilized Pickering emulsions was evaluated. RESULTS: Pulsed ultrasound changed the particle size of SPP and its conformation. As the pulsed ultrasound increased from 0 s to 5 s, the α-helix and SS contents of SPP decreased, whereas the ß-sheet and SH contents increased, which in turn improved its solubility and amphiphilicity. As a result, the SPP treated by a combination of 12 h of hydration and 3 s of ultrasound exhibited a contact angle of 74.95°, hydrophobicity of 904.83, EAI of 6.66 m2 g-1 and ESI of 190.69 min. Compared with the combination of 1 h of hydration and 5 s of ultrasound, the combination of 12 h of hydration and 3 s of ultrasound exerted more soluble and hydrophobic SPP, whereas the EAI and ESI of the samples were higher. Notably, the ultrasound-treated SPP can form a stable gel-like emulsion (oil fraction ranging from 70% to 80%). CONCLUSION: The combination of hydration and ultrasound can effectively improve the physicochemical characteristics of SPP as well as its emulsion stability. Sufficient hydration is a cost-effective method for facilitating the modification of proteins by ultrasound treatment. © 2024 Society of Chemical Industry.


Subject(s)
Bombyx , Emulsions , Hydrophobic and Hydrophilic Interactions , Insect Proteins , Particle Size , Pupa , Solubility , Animals , Emulsions/chemistry , Bombyx/chemistry , Insect Proteins/chemistry , Pupa/chemistry , Ultrasonic Waves , Emulsifying Agents/chemistry , Water/chemistry
18.
Small ; 20(29): e2310851, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38334256

ABSTRACT

Inspired by the timely emergence of silkworm pupae from their cocoons, silkworm chrysalis-like probiotic composites (SCPCs) are developed for the comprehensive therapy of inflammatory bowel disease (IBD), in which probiotics are enveloped as the "pupa" in a sequential layering of silk sericin (SS), tannic acid (TA), and polydopamine, akin to the protective "cocoon". Compared to unwrapped probiotics, these composites not only demonstrate exceptional resistance to the harsh gastrointestinal environment and exhibit over 200 times greater intestinal colonization but also safeguard probiotics from the damage of IBD environment while enabling probiotics sustained release. The probiotics, in synergy with SS and TA, provide a multi-crossed comprehensive therapy for IBD that simultaneously addresses various pathological features of IBD, including intestinal barrier disruption, elevated pro-inflammatory cytokines, heightened oxidative stress, and disturbances in the intestinal microbiota. SCPCs exhibit remarkable outcomes, including a 9.7-fold reduction in intestinal permeability, an 8.9-fold decrease in IL-6 levels, and a 2.9-fold reduction in TNF-α levels compared to uncoated probiotics. Furthermore, SCPCs demonstrate an impressive 92.25% reactive oxygen species clearance rate, significantly enhance the richness of beneficial intestinal probiotics, and effectively diminish the abundance of pathogenic bacteria, indicating a substantial improvement in the overall therapeutic effect of IBD.


Subject(s)
Bombyx , Inflammatory Bowel Diseases , Probiotics , Animals , Bombyx/chemistry , Inflammatory Bowel Diseases/therapy , Inflammatory Bowel Diseases/drug therapy , Intestines , Polymers/chemistry , Gastrointestinal Microbiome/drug effects , Sericins/chemistry , Sericins/pharmacology , Indoles/chemistry , Tannins/chemistry , Tannins/pharmacology , Mice
19.
Int J Biol Macromol ; 264(Pt 1): 130374, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38408575

ABSTRACT

Silk is a natural engineering material with a unique set of properties. The major constituent of silk is fibroin, a protein widely used in the biomedical field because of its mechanical strength, toughness and elasticity, as well as its biocompatibility and biodegradability. The domestication of silkworms allows large amounts of fibroin to be extracted inexpensively from silk cocoons. However, the industrial extraction process has drawbacks in terms of sustainability and the quality of the final medical product. The heterologous production of fibroin using recombinant DNA technology is a promising approach to address these issues, but the production of such recombinant proteins is challenging and further optimization is required due to the large size and repetitive structure of fibroin's DNA and amino acid sequence. In this review, we describe the structure-function relationship of fibroin, the current extraction process, and some insights into the sustainability of silk production for biomedical applications. We focus on recent advances in molecular biotechnology underpinning the production of recombinant fibroin, working toward a standardized, successful and sustainable process.


Subject(s)
Bombyx , Fibroins , Animals , Bombyx/chemistry , Fibroins/chemistry , Biocompatible Materials/chemistry , Biotechnology , Silk/chemistry
20.
Food Chem ; 445: 138761, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38367561

ABSTRACT

The silkworm (Bombyx mori) has long been valued food and feed in East Asia for its abundant nutritional and medicinal attributes, conversely, it can elicit allergic responses in susceptible individuals. Therefore, the development of silkworm detection method is required to avert allergenic incidents. In this study, two methodologies, tandem mass spectrometry (LC-MS/MS) and real-time PCR, were developed to achieve effective silkworm detection. These methods exhibited exceptional sensitivity in identifying silkworm presence in processed foods. Furthermore, model cookies spiked with silkworm were used to validate the sensitivities of LC-MS/MS (0.0005%) and real-time PCR (0.001%). Overall, these techniques were useful for trace silkworm detection in food products; therefore, they may help prevent allergic reactions. To the best of our knowledge, this study represents the first comparison of LC-MS/MS and real-time PCR methods for silkworm detection, marking an important contribution to the field. Data are available from ProteomeXchange under identifier PXD042494.


Subject(s)
Bombyx , Hypersensitivity , Animals , Humans , Bombyx/genetics , Bombyx/chemistry , Liquid Chromatography-Mass Spectrometry , Tandem Mass Spectrometry , Chromatography, Liquid , Real-Time Polymerase Chain Reaction , Allergens/genetics
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