Silkworm Bombyx Mori Research Articles

Influence of the chemical composition of mulberry on the growth dynamics of silkworm larvae

In countries where sericulture is well-developed, there is a pressing need to create new systems, varieties, and hybrids of the Morus alba L. species, which is the only food source for the mulberry silkworm Bombyx mori L. These new systems should be suitable for the care of silkworms, and their nutritional and chemical composition should be studied. The introduction of these new systems into production is considered a crucial problem that needs to be addressed. Research experiments were carried out in 2013-2017 at the Tashkent State Agrarian University and the Silk Research Institute. The results showed that in 2017, the new varieties contained 75.1-74.3% water, while in 2018, the water content was 76.0-77.3%. Meanwhile, the Tajikskaya bezsemyannaya variety showed an increase in this indicator, reaching 75.2-76.2%. However, these results were still lower than the benchmark of 98.8-101.4%. The amount of protein is one of the most important indicators of mulberry leaf composition.

Molecular weight and molecular weight distribution of sericin protein extracted from cocoon waste of <i>Bombyx mori</i>

Silk sericin comprises a globular water-soluble protein that surrounds silk fibres, sticking them together and providing cocoon adhesion. Sericin was isolated from the extract solution in two ways: the first sample was obtained by concentrating the filtered extract at low pressure (SLP); the second sample was obtained by ultrafiltration (SUF) using a membrane. In this work, the size exclusion-high-performance liquid chromatography involving viscometry and refractive index detectors was used to determine the molecular weight and conformation of sericin polypeptides obtained from cocoons of the Bombyx mori silkworm. The aggregation processes of silk sericin protein under various isolation conditions from the solution were considered. It was shown that sericin macromolecules are present as a monodisperse polypeptide at low concentrations, which aggregates at concentrations greater than 1–2 mg/ml. The obtained data indicate that, along with the parameters of the extraction process, the conditions for its isolation from the solution, including temperature, pressure and degree of concentration, affect the molecular weight and aggregative behaviour of the protein. The results confirm and complement previously obtained data on the influence of various factors on the association of protein macromolecules in solution. The resulting sericin fractions can find many applications, including materials for tissue engineering, coatings for surface modification, cell culture media, cosmetics, as well as food additives and medical biomaterials.

Effects of magnetic field on the histology of silk gland of silkworm, Bombyx mori L. (Lepidoptera, Bombycidae)

Magnetic field influences the physiology and development of living organisms, depending up on the strength of magnetic field. In silkworm, it enhances enzymes, proteins and nucleic acids of silk gland. On this line, histology of silk gland of silkworm Bombyx mori L. (Lepidoptera, Bombycidae) was studied after its magnetization, at 3500 G and 4000 G separately. Exposure of silkworm to magnetic field resulted in increase in diameter of its silk gland/lumen of silk gland/space occupied by secretory substance (silk protein-fibroin). The studies showed 46.15 and 21.19 per cent increase in diameter of silk gland of larvae exposed to 3500 G and 4000 G magnetic field respectively than that in control larvae. Larvae treated with 3500 G magnetic field and 4000 G magnetic field exhibited 51 per cent gain and 1.29 per cent loss in the size of secretory substance respectively than that of control group larvae. Cellular thickness is more in magnetized larvae than that of control larvae. This is favourable for sericulture.

Comparison of Long-Read Methods for Sequencing and Assembly of Lepidopteran Pest Genomes

Lepidopteran species are mostly pests, causing serious annual economic losses. High-quality genome sequencing and assembly uncover the genetic foundation of pest occurrence and provide guidance for pest control measures. Long-read sequencing technology and assembly algorithm advances have improved the ability to timeously produce high-quality genomes. Lepidoptera includes a wide variety of insects with high genetic diversity and heterozygosity. Therefore, the selection of an appropriate sequencing and assembly strategy to obtain high-quality genomic information is urgently needed. This research used silkworm as a model to test genome sequencing and assembly through high-coverage datasets by de novo assemblies. We report the first nearly complete telomere-to-telomere reference genome of silkworm Bombyx mori (P50T strain) produced by Pacific Biosciences (PacBio) HiFi sequencing, and highly contiguous and complete genome assemblies of two other silkworm strains by Oxford Nanopore Technologies (ONT) or PacBio continuous long-reads (CLR) that were unrepresented in the public database. Assembly quality was evaluated by use of BUSCO, Inspector, and EagleC. It is necessary to choose an appropriate assembler for draft genome construction, especially for low-depth datasets. For PacBio CLR and ONT sequencing, NextDenovo is superior. For PacBio HiFi sequencing, hifiasm is better. Quality assessment is essential for genome assembly and can provide better and more accurate results. For chromosome-level high-quality genome construction, we recommend using 3D-DNA with EagleC evaluation. Our study references how to obtain and evaluate high-quality genome assemblies, and is a resource for biological control, comparative genomics, and evolutionary studies of Lepidopteran pests and related species.

Dietary Inclusion of Defatted Silkworm (Bombyx mori L.) Pupa Meal for Broiler Chickens at Different Ages: Growth Performance, Carcass and Meat Quality Traits.

The present study was conducted to assess the effects of a 4% defatted silkworm (SWM-DEF) meal dietary incorporation into chickens' diet at different growth stages on growth performances, carcass, and meat quality traits. A total of 90 Ross 308 one-day-old male broiler chickens were randomly allocated into 3 dietary groups of 5 replicated pens/diet (6 chickens/pen). One group was fed a standard soybean-based diet (C); group SWM1 consumed a starter diet (1-10 days of age) including 4% SWM-DEF and then the C diet up to slaughter (11-42 days of age); group SWM2 was fed with the C diet in the starter phase and the 4% SWM-DEF diet up to slaughter. Individual live weight and pen feed intake were determined at the end of each feeding phase: starter, grower, and finisher. Weight gain and FCR were then calculated. At 42 days of age, chickens were slaughtered and carcass traits determined. Leg and breast physico-chemical meat quality was also evaluated. Results confirmed that SWM-DEF could be a possible alternative feed source for chickens since growth performance, carcass, and meat physical traits were overall comparable in the three treatment groups. The feeding stage seemed to play a relevant impact on the sole meat protein content (SWM1 < SMW2 and C; p < 0.001). Concluding, the results available to date indicate that 4% SWM-DEF can be provided to chickens in different growth phases, and the choice of the inclusion period is more an industrial cost-benefit evaluation. From the scientific point of view, however, an administration in the grower-finisher phase rather than in the starter one provided the best meat nutritional quality. Further investigations should focus on the impact on meat fatty acids profile and sensory traits, which are of utmost importance for consumers.

Sustainable Prebiotic Dessert with Sericin Produced by Bombyx mori Worms

(1) Background: The processing of silk threads secreted by the silkworm Bombyx mori leads to large amounts of sericin as textile waste. Its biochemical and medical properties open a new perspective for its use in the food industry and its authorization as a new food ingredient in the European Union, by the European Commission and the European Food Safety Authority. (2) Methods: Experimental and physico–chemical analyzes were carried out to obtain a sustainable prebiotic dessert with low energy value, containing Sericin produced by Bombyx Mori, which does not contain sugar and can be consumed both by people who want a healthy diet and people who need food for special nutritional conditions, such as diabetes, dysphagia or inflammatory diseases. (3) Results: The sustainable jelly was made from depectinized apple juice, pectin, sericin, lactoferrin, stevia and pectin. This dessert is natural and can be certified organic and HALAL. (4) Conclusions: Sericin can be used in the manufacture of a very wide range of foods. Being a glycoprotein, it can also be used to obtain jelling foods with low energy value, including foods for patients with dysphagia. This represents an important sustainable resource of essential amino acids for the normal homeostasis of the human body.

Sericin as a Nutritional Supplement to Enhance Cocoon, Pupal Parameters and Grainase Properties of Silkworm Bombyx mori L.

During the raw silk degumming process, the water-soluble natural protein sericin is discarded as waste material in the sericulture industry of Bangladesh. In this study, various amount of sericin (as nutritional supplement) treated mulberry leaves was fed to three different silkworm groups and its effect on cocoon, pupal parameters as well as grainase properties of the silkworms was evaluated. The results indicated that fecundity increased with the decrease of the concentration of sericin for all treatment groups. There was no significant difference among the treatment groups and the control group for fecundity value, but in the case of hatching percentage (%), all the treatment groups showed the reverse trend with fecundity. Cocoon production was increased by 23.91% when silkworm was fed with 0.50% sericin-treated mulberry leaves at chawki stage (first to the third instar) compared to the control group.

Silkworm pupae derivatives as source of high value protein intended for pasta fortification

Silkworm (Bombyx mori) pupae are recognized as novel nutritionally valuable food. Their use in pasta-making was considered with the intention of repositioning spaghetti shaped pasta supplemented with silkworm derivatives (10%db ) as a valuable product in sustainable diets besides upcycling a side stream from the silk industry. The principal objective of this study was to assess the cooking quality (i.e., imbibition kinetics, cooking loss) and texture of pasta supplemented with defatted silkworm powder or with its aqueous protein extract, which enabled to reduce the content of indigestible components supplying a similar protein intake. Pasta was produced on lab-scale, dried, and tested for chemical composition, mechanical properties before and during cooking, cooking behavior in terms of hydration kinetics, starch gelatinization, and cooking quality indexes. The structural roles on pasta protein network played by silkworm powder and proteins extract were investigated. The former behaves as a structural thickener while the second provides a steric hindrance effect with consequent different cooking performances. With regards to the fortified pasta perceived quality, a high level in total color difference (ΔE) was measured (ΔE>6). However, after fortification agents' addition, pasta color became closer to that of the whole wheat pasta already known by consumers. Structure fragility increased. The energy at break of the "extract pasta" was about one-third of the control (0.849 N*mm). Silkworm powder addition led to the highest pasta optimal cooking time (376 s) and the slowest imbibition rate (0.0001 s-1 ). After fortification, pasta had an almost doubled cooking loss than control pasta (2.97±0.18g/100gdb ). PRACTICAL APPLICATION: Silkworm pupae flour can be easily applied for pasta fortification in order to increase the protein daily intake of people in an easy and practical way.

Cell-based analysis reveals that sex-determining gene signals in Ostrinia are pivotally changed by male-killing Wolbachia.

Wolbachia, a maternally transmitted bacterium, shows male-killing, an adaptive phenotype for cytoplasmic elements, in various arthropod species during the early developmental stages. In lepidopteran insects, lethality of males is accounted for by improper dosage compensation in sex-linked genes owing to Wolbachia-induced feminization. Herein, we established Ostrinia scapulalis cell lines that retained sex specificity per the splicing pattern of the sex-determining gene doublesex (Osdsx). We found that Wolbachia transinfection in male cell lines enhanced the female-specific splice variant of Osdsx (OsdsxF ) while suppressing the male-specific variant (OsdsxM ), indicating that Wolbachia affects sex-determining gene signals even in vitro. Comparative transcriptome analysis isolated only two genes that behave differently upon Wolbachia infection. The two genes were respectively homologous to Masculinizer (BmMasc) and zinc finger-2 (Bmznf-2), male-specifically expressed sex-determining genes of the silkworm Bombyx mori that encode CCCH-type zinc finger motif proteins. By using cultured cells and organismal samples, OsMasc and Osznf-2 were found to be sex-determining genes of O. scapulalis that are subjected to sex-specific alternative splicing depending upon the chromosomal sex, developmental stage, and infection status. Overall, our findings expound the cellular autonomy in insect sex determination and the mechanism through which sex is manipulated by intracellular selfish microbes.

Effect of nucleopolyhedrosis virus on silkworm bombyx mori linn and its transmission from further generation

Effect of nucleopolyhedrosis virus on silkworm bombyx mori linn and its transmission from further generation

Silk Fibroin as an Efficient Biomaterial for Drug Delivery, Gene Therapy, and Wound Healing.

Silk fibroin (SF), an organic material obtained from the cocoons of a silkworm Bombyx mori, is used in several applications and has a proven track record in biomedicine owing to its superior compatibility with the human body, superb mechanical characteristics, and its controllable propensity to decay. Due to its robust biocompatibility, less immunogenic, non-toxic, non-carcinogenic, and biodegradable properties, it has been widely used in biological and biomedical fields, including wound healing. The key strategies for building diverse SF-based drug delivery systems are discussed in this review, as well as the most recent ways for developing functionalized SF for controlled or redirected medicines, gene therapy, and wound healing. Understanding the features of SF and the various ways to manipulate its physicochemical and mechanical properties enables the development of more effective drug delivery devices. Drugs are encapsulated in SF-based drug delivery systems to extend their shelf life and control their release, allowing them to travel further across the bloodstream and thus extend their range of operation. Furthermore, due to their tunable properties, SF-based drug delivery systems open up new possibilities for drug delivery, gene therapy, and wound healing.

Growth and Productivity of Silkworm Bombyx mori L. (Lepidoptera: Bombicidae) Given Mulberry (Morus sp.) It Contains Vitamin B1

The effect of mulberry leaves that contain vitamin B1on the growth and productivity of silkworms (Bombyx mori L.) was studied. This research used Completely Randomized Design (CRD) with the treatments were 10 silkworm feed with an untreated control leaves and an addition 0.1, 0.2, 0.3 and 0.4 mg/100ml of vitamin B1. Every treatment consisted of 3 replications. The results showed that an addition of vitamin B1 inhibited the growth, morphological structure of instars III, and IV such as head length, head diameter, body length, and body diameter, the weight of instars III, V, and the percentage of cocoon shell. Vitamin B1 has no effect on the morphological structures of instars V, the weight of instars IV, the pupae weight, the fiber length, the fiber percentage, the cocoon weight, and the cocoon shell weight. However, the frontal and posterior glands were decreased at the concentration 0.4 mg/100ml

Silk Sericin: A Promising Sustainable Biomaterial for Biomedical and Pharmaceutical Applications.

Silk is a natural composite fiber composed mainly of hydrophobic fibroin and hydrophilic sericin, produced by the silkworm Bombyx mori. In the textile industry, the cocoons of B. mori are processed into silk fabric, where the sericin is substantially removed and usually discarded in wastewater. This wastewater pollutes the environment and water sources. However, sericin has been recognized as a potential biomaterial due to its biocompatibility, immunocompatibility, biodegradability, anti-inflammatory, antibacterial, antioxidant and photoprotective properties. Moreover, sericin can produce hydrogels, films, sponges, foams, dressings, particles, fibers, etc., for various biomedical and pharmaceutical applications (e.g., tissue engineering, wound healing, drug delivery, cosmetics). Given the severe environmental pollution caused by the disposal of sericin and its beneficial properties, there has been growing interest in upcycling this biomaterial, which could have a strong and positive economic, social and environmental impact.

Haemolymph amylase activities in different silkworm (Bombyx mori L.) breeds during the last four days of 5th instar and correlation studies with economic traits

Haemolymph amylase activities in different silkworm (Bombyx mori L.) breeds during the last four days of 5th instar and correlation studies with economic traits

A Wolbachia factor for male killing in lepidopteran insects

Bacterial symbionts, such as Wolbachia species, can manipulate the sexual development and reproduction of their insect hosts. For example, Wolbachia infection induces male-specific death in the Asian corn borer Ostrinia furnacalis by targeting the host factor Masculinizer (Masc), an essential protein for masculinization and dosage compensation in lepidopteran insects. Here we identify a Wolbachia protein, designated Oscar, which interacts with Masc via its ankyrin repeats. Embryonic expression of Oscar inhibits Masc-induced masculinization and leads to male killing in two lepidopteran insects, O. furnacalis and the silkworm Bombyx mori. Our study identifies a mechanism by which Wolbachia induce male killing of host progeny.

The gut microbiota of silkworm are altered by antibiotic exposure.

In recent years, antibiotics have frequently been detected in soil, lakes, and rivers. Antibiotic residues in the environment may alter microbial structure and cause bacterial resistance, but their effect on interactions among host microbiota is still poorly understood. To investigate this issue, here we used silkworm (Bombyx mori) fed on antibiotic-treated mulberry leaf as a model to explore the effects of antibiotic exposure on gut bacteria and fungi. We observed that elimination of fungi significantly reduced bacterial richness and diversity in silkworm intestine after exposure to the antifungal amphotericin B, while the elimination of bacteria dramatically increased the richness and diversity of fungi after exposure to the antibacterial ampicillin-streptomycin. Thus, antibiotic-treated mulberry leaf significantly altered the community structure of microbiota in the gut of silkworm. Clearance of gut bacteria enhanced the correlation between gut fungi and leaf-derived fungi, while clearance of gut fungi promoted abnormal proliferation of gut bacteria. These data provide a simple model to explore the comprehensive effect of diet-derived bacteria, fungi, and antibiotics on gut microbiota.

Structural basis for the carotenoid binding and transport function of a START domain

STARD3, a steroidogenic acute regulatory lipid transfer protein, was identified as a key xanthophyll-binding protein in the human retina. STARD3 and its homologs in invertebrates are known to bind and transport carotenoids, but this lacks structural elucidation. Here, we report high-resolution crystal structures of the apo- and zeaxanthin (ZEA)-bound carotenoid-binding protein from silkworm Bombyx mori (BmCBP). Having a STARD3-like fold, BmCBP features novel elements, including the Ω1-loop that, in the apoform, is uniquely fixed on the α4-helix by an R173-D279 salt bridge. We exploit absorbance, Raman and dichroism spectroscopy, and calorimetry to describe how ZEA and BmCBP mutually affect each other in the complex. We identify key carotenoid-binding residues, confirm their roles by ZEA-binding capacity and X-ray structures of BmCBP mutants, and also demonstrate that markedly different carotenoid-binding capacities of BmCBP and human STARD3 stem from differences in the structural organization of their carotenoid-binding cavity.

Genome-wide screening of genes involved in programming diapause in the next generation in silkworm, Bombyx mori (Lepidoptera: Bombycidae)

Maternal silkworms (Bombyx mori) of bivoltine strains are destined to produce either diapause or non-diapause eggs depending on environmental factors, such as, temperature and photoperiod experienced during the egg and larval stages. However, the molecular mechanisms that program diapause, which depend on information about the environment, remain unclear. We aimed to identify genes that are involved in programming diapause in the next generation in bivoltine silkworms. We therefore screened differentially expressed genes (DEGs) in the larval brains of diapause- and non-diapause-egg producers kept under three different diapause-inducing conditions using cap analysis of gene expression. Under each condition, only temperature, illumination or photoperiod was changed during the egg or larval stage as a diapause-controlling stimulus to induce the production of diapause or non-diapause eggs. We then verified the expression of DEGs that were common to all the three conditions using real-time quantitative PCR. We investigated the functional involvement of candidate genes in programming diapause using double-stranded RNA interference (RNAi) for gene knockdown. The results showed more abundant juvenile hormone acid methyltransferase (Jhamt) and proton-coupled folate transporter (Pcft) gene expression in the brains of fifth instar larvae of producers of diapause eggs than those of non-diapause eggs under the three conditions. Furthermore, RNAi against either of these genes significantly decreased the incidence of diapause in the next generation. These findings indicate that both Jhamt and Pcft are involved in the programming of diapause in the silkworm brain. These genes could function in retaining information that leads to diapause in the next generation.

Studies on Synergistic Effects of Different Bio-Active Chemicals on Nuclearpolyherosis (Grasserie Disease) of Silkworm, Bombyx mori Linnaeus

Purpose: Larval hind gut of multivoltine breed silk worm Bombyx mori L. (Nistari) was studied in both favourable and unfavourable rearing seasons after Grasserie caused by Bombyx mori Nuclearpolyherosis Virus (BmNPV) using Histological Analysis, Scanning Electron Microscopy and Transmission Electronic Microscopy.
 Methodology: Chemical treatments using various bio active chemicals: Curcumin, Allicin and Azadirachtin were administered to minimize the extent of damage.
 Findings: The present study clearly indicates that Azadirachtin is more effective in comparison to its other counterparts and it is the major finding of this extensive study.
 Unique Contribution to Theory, Policy and Practice: The uniqueness of this type of bio chemical control of Grasserie disease which is not only a cost effective and eco-friendly technique, but also it is less hazardous and simple controlling procedure of Grasserie. Therefore, this extensive study may help the stakeholders to step ahead on the progression of sustainable agriculture while avoiding crop loss by means of cost-effective pathogen management technology.

Comparative Transcriptome Analysis Identifies Key Defense Genes and Mechanisms in Mulberry (Morus alba) Leaves against Silkworms (Bombyx mori).

As a consequence of long-term coevolution and natural selection, the leaves of mulberry (Morus alba) trees have become the best food source for silkworms (Bombyx mori). Nevertheless, the molecular and genomic basis of defense response remains largely unexplored. In the present study, we assessed changes in the transcriptome changes of mulberry in response to silkworm larval feeding at 0, 3, and 6 h. A total of 4709 (up = 2971, down = 1738) and 3009 (up = 1868, down = 1141) unigenes were identified after 3 and 6 h of silkworm infestation, respectively. MapMan enrichment analysis results show structural traits such as leaf surface wax, cell wall thickness and lignification form the first physical barrier to feeding by the silkworms. Cluster analysis revealed six unique temporal patterns of transcriptome changes. We predicted that mulberry promoted rapid changes in signaling and other regulatory processes to deal with mechanical damage, photosynthesis impairment, and other injury caused by herbivores within 3-6 h. LRR-RK coding genes (THE1, FER) was predicted participated in perception of cell wall perturbation in mulberry responding to silkworm feeding. Ca2+ signal sensors (CMLs), ROS (OST1, SOS3), RBOHD/F, CDPKs, and ABA were part of the regulatory network after silkworm feeding. Jasmonic acid (JA) signal transduction was predicted to act in silkworm feeding response, 10 JA signaling genes (such as OPR3, JAR1, and JAZ1) and 21 JA synthesis genes (such as LOX2, AOS, and ACX1) were upregulated after silkworm feeding for 3 h. Besides, genes of "alpha-Linolenic acid metabolism" and "phenylpropanoid biosynthesis" were activated in 3 h to reprogram secondary metabolism. Collectively, these findings provided valuable insights into silkworm herbivory-induced regulatory and metabolic processes in mulberry, which might help improve the coevolution of silkworm and mulberry.