Search Results (23)

Sexual reproduction is the predominant mode of reproduction in animals, and spermatogenesis is the fundamental step in this process. As the model organism for lepidopteran, the silkworm Bombyx mori exhibits typical dichotomous spermatogenesis, producing both nucleated (eupyrene) and anucleate (apyrene) sperm. Leucylaminopeptidases (LAPs), members of the M17 metalloprotease family, are characterized by their ability to cleave leucine residues from the N-terminus of peptides. In addition to this canonical function, they have been implicated in male fertility in mammals and Diptera. Nevertheless, whether LAPs are required for dimorphic spermatogenesis in Lepidoptera remains to be clarified. Here, we demonstrated that Sperm-Leucylaminopeptidase (S-LAP) plays vital roles in the silkworm eupyrene sperm development. Similar to the testis-specific expression pattern of eight S-LAPs in Drosophila melanogaster, BmS-LAP was also predominantly expressed in testis. Depletion of BmS-LAP via CRISPR/Cas9 system resulted in male sterility, while the fertility of female mutant was unaffected. Notably, male mutants displayed severe defects in the formation and migration of eupyrene sperm, whereas apyrene sperm development appeared normal. In addition, RNA-seq and qRT-PCR analyses demonstrated that spermatogenesis defects were associated with energy metabolism and flagellar assembly. Our study provides the first evidence that LAP is necessary for dimorphic spermatogenesis in Lepidopteran, offering new insights into the molecular basis of male infertility. Full article

Sericin is a major polypeptidic constituent of the silk in the cocoons produced by the Bombyx mori silkworm. Certain fractions isolated from sericin exhibited antioxidant properties in a variety of reported experimental settings. In a previous study, we found that only the non-protein fraction, extracted from crude sericin, displayed antioxidative activity in cultures of murine retinal photoreceptor cells (661W), a cell line that is highly sensitive to oxidative stress associated with diseases of the retina. In the same assay, the protein fraction (purified sericin) did not show any such activity. To check these findings, in the present study, two additional different assays were employed: an in vitro assay based on the dose-dependent mitigating effects exerted by each sericin fraction on the activity of antimycin A in cultures of 661W cells and an in vivo assay based on an animal (rat) model of retinal ischemia/reperfusion injury. In both assays, nitroxide was appended as a fluorometric molecular probe, and fluorescent intensity was monitored by either flow cytometry (in vitro) or the Micron IV retinal imaging system (in vivo). The in vitro assay indicated unequivocally antioxidative capacity for the non-protein fraction and a lack of it for the purified sericin. The in vivo assay indicated that each fraction was able to act as an antioxidant. We hypothesized that the ability of purified sericin to display antioxidative activity in vivo, but not in vitro, was the result of the metabolic degradation of sericin, a process that delivered serine, an amino acid with known antioxidant properties. However, this hypothesis needs experimental confirmation. Full article

Background/Objective: Platelet concentrates (PCs) are used in transfusion medicine to treat bleeding disorders. Staphylococcus aureus, a predominant PC contaminant, has been implicated in several adverse transfusion reactions. The aim of this study was to investigate the impact of PC storage on S. aureus resistance to quinolones, which are commonly used to treat S. aureus infections. Methods/Results: Four transfusion-relevant S. aureus strains (TRSs) were subjected to comparative transcriptome analyses when grown in PCs vs. trypticase soy broth (TSB). Results of these analyses revealed differentially expressed genes involved in antibiotic resistance. Of interest, the norB gene (encodes for the NorB efflux pump, which is implicated in quinolone resistance and is negatively regulated by MgrA) was upregulated (1.2–4.7-fold increase) in all PC-grown TRS compared to TSB cultures. Minimal Bactericidal Concentration (MBC) of ciprofloxacin and norfloxacin in PC-grown TRS compared to TSB showed increased resistance to both quinolones in PC cultures. Complementary studies with non-transfusion-relevant strains S. aureus RN6390 and its norB and mgrA deletion mutants were conducted. MBC of ciprofloxacin and norfloxacin and RT-qPCR assays of these strains showed that not only norB, but also norA and norC may be involved in enhanced quinolone resistance in PC-grown S. aureus. The role of norB in S. aureus virulence was also tested using the silkworm Bombyx mori animal model; lethal dose 50 (LD₅₀) assays revealed slightly higher virulence in larvae infected with the wild-type strain compared to the norB mutant. Conclusions: The PC storage environment enhances quinolone resistance in S. aureus and induces differential expression of efflux pump nor genes. Furthermore, our preliminary data of the involvement of NorB in virulence of S. aureus using a silkworm model merit further investigation with other systems such as a mammal animal model. Our results provide mechanistic insights to aid clinicians in the selection of antimicrobial treatment of patients receiving transfusions of S. aureus-contaminated PCs. Full article

Background: Osteoporosis is a bone remodeling disease characterized by an imbalance between bone formation and resorption, leading to bone fragility. Current treatments focus on bone resorption suppression but often have adverse effects. This study aimed to explore the potential of sericin, a silkworm-derived protein, as a dual-action therapeutic agent that enhances bone formation through its component L-serine and inhibits bone resorption via D-serine, which is derived from L-serine by the action of serine racemase. Methods: Cellular experiments were conducted to evaluate the effects of L-serine on osteoblast differentiation and D-serine on osteoclast inhibition. Serum levels of D-serine were measured following sericin administration in an osteoporosis animal model. μ-CT analysis assessed trabecular and cortical bone quality, and bone-related protein expression was analyzed using immunoprecipitation-based high-performance liquid chromatography (IP-HPLC). Results: L-serine significantly upregulated osteogenic markers, including alkaline phosphatase (ALP), Runx2, osterix, and Col1a1, in osteoblasts (p < 0.05). D-serine inhibited osteoclast activation by suppressing cathepsin K expression (p < 0.001). Sericin feeding elevated serum D-serine levels (p < 0.001) and upregulated bone-related proteins such as BMP-2, osterix, and Runx2. Micro-computed tomography (μ-CT) analysis revealed significant improvements in trabecular bone parameters in the OVX-sericin group, including increased trabecular bone volume (Tb.BV/TV; p < 0.05) and reduced trabecular separation (Tb.Sp; p < 0.05), compared to the OVX and OVX-amino acid groups. Cortical bone parameters, including cortical bone volume (Ct.BV/TV) and cortical area (Ct.Ar), did not significantly differ among OVX groups, but all were lower than in the sham group (p < 0.05). Conclusions: This study demonstrates that sericin modulates bone metabolism by enhancing osteoblast activity through L-serine and inhibiting osteoclastogenesis via D-serine. Sericin supplementation improved trabecular bone mass in an osteoporosis model, highlighting its potential for bone health. Full article

To contrast the rapid spread of antibiotic resistance in bacteria, new alternative therapeutic options are urgently needed. The use of nanoparticles as carriers for clinically relevant antibiotics represents a promising solution to potentiate their efficacy. In this study, we used Bombyx mori larvae for the first time as an animal model for testing a nanoconjugated glycopeptide antibiotic (teicoplanin) against Staphylococcus aureus infection. B. mori larvae might thus replace the use of mammalian models for preclinical tests, in agreement with the European Parliament Directive 2010/63/EU. The curative effect of teicoplanin (a last resort antibiotic against Gram-positive bacterial pathogens) conjugated to iron oxide nanoparticles was assessed by monitoring the survival rate of the larvae and some immunological markers (i.e., hemocyte viability, phenoloxidase system activation, and lysozyme activity). Human physiological conditions of infection were reproduced by performing the experiments at 37 °C. In this condition, nanoconjugated teicoplanin cured the bacterial infection at the same antibiotic concentration of the free counterpart, blocking the insect immune response without causing mortality of silkworm larvae. These results demonstrate the value and robustness of the silkworm as an infection model for testing the in vivo efficacy of nanoconjugated antimicrobial molecules. Full article

The increasing prevalence of diabetic reproductive complications has prompted the development of innovative animal models. The use of the silkworm Bombyx mori as a model for diabetic reproductive damage shows potential as a valuable research tool. This study employed silkworms as a novel model to investigate diabetic reproductive damage. The silkworms were fed a high-glucose diet containing 10% glucose to induce a diabetic model. Subsequently, the study concentrated on assessing the influence of diabetes on the reproductive system of male silkworms. The results indicate that diabetes resulted in reduced luteinizing hormone (LH) and testosterone (T) levels, as well as elevated triglyceride (TG) levels in male silkworms. Moreover, diabetes mellitus was associated with pathological testicular damage in male silkworms, accompanied by decreased glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) levels, along with increased malondialdehyde (MDA) levels in the testis. Additionally, diabetes mellitus reduced the expression of siwi1 and siwi2 genes in the testis of male silkworms. Overall, these results support using silkworms as a valuable model for studying diabetic reproductive damage. Full article

Diet plays a crucial role in shaping the gut microbiota and overall health of animals. Traditionally, silkworms are fed fresh mulberry leaves, and artificial diets do not support good health. The aim of this study was to explore the relationship between the dietary transition from artificial diets to mulberry leaves and the effects on the gut microbiota and physiological changes in silkworms as a model organism. With the transition from artificial diets to mulberry leaves, the diversity of the silkworm gut microbiota increased, and the proportion of Enterococcus and Weissella, the dominant gut bacterial species in silkworms reared on artificial diets, decreased, whereas the abundance of Achromobacter and Rhodococcus increased. Dietary transition at different times, including the third or fifth instar larval stages, resulted in significant differences in the growth and development, immune resistance, and silk production capacity of silkworms. These changes might have been associated with the rapid adaptation of the intestinal microbiota of silkworms to dietary transition. This study preliminarily established a dietary transition–gut microbial model in silkworms based on the conversion from artificial diets to mulberry leaves, thus providing an important reference for future studies on the mechanisms through which habitual dietary changes affect host physiology through the gut microbiome. Full article

Starvation imposes significant stress on animal survival and development, resulting in organ damage within the organism. The brain, being one of the most vital organs in animals, plays a crucial role in coordinating the physiological functions of other organs. However, performing brain experiments on the human body is challenging. In this work, we selected the silkworm, a model Lepidoptera organism, due to its favorable characteristics. A comprehensive transcriptome analysis was conducted on the brain of silkworm subjected to starvation treatment. The analysis of differentially expressed genes revealed significant alterations in 330 genes following the period of starvation. Through an enrichment analysis, we successfully identified pathways associated with metabolism, hormones, immunity, and diseases. Our findings highlight the transcriptional response of the brain to starvation, providing valuable insights for comprehending the impact of starvation stress in other animals. Full article

This work reports the biological toxicity of nano plastic particles (NPs) to silkworms fed on the bait dopped with polystyrene encapsulated luminescent nanoparticles. The processes of NPs intake and excretion were monitored by means of time-gated optical imaging (TGI) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), which allowed the quantification of the spatiotemporal deposition of NPs in an individual silkworm. The rates of NPs excretion and sequestration were found to be 99.92% and 0.08%, respectively, and the NPs retentate stayed mainly in the fat body (67.7%), digestive tract (18.0%), and head (7.54%). Adverse effects of NPs exposure were accordingly confirmed such as growth retardation and smaller physique. The results of the present work confirmed the possibility of nano-plastics accumulating and transmitting along the food chain in terrestrial ecosystems. The present work demonstrates the potential of employing silkworm as a model of full metamorphosed insects for exploring the biological impact of NPs on congeneric terrestrial animals, as well as the efficacy of the TGI-MS modality for in situ visualizing and quantifying the propagation of NPs via the primary food chain. Full article

Bombyx mori is an ideal lepidopteran species representative of many scientific studies, a model of studies for medicine and a significant insect from an ecological standpoint. This review was performed to summarize the fatty acids (FA) composition of silkworm pupae (SP) that are associated with other important compounds that could add value to SP, diversifying the ways of valorization. The proposal to complete plant-based feeds with insect-based feeds represents a viable option to beneficially impact human and animal health and the environment. The quality and quantity of fats consumed significantly impact the aetiology of certain diseases. The key compounds of fat named essential FA (EFA) substantially influence the prevention and treatment of several diseases through their nutraceutical functions. Due to its excellent profile in nutrients such as protein and fat, amino acids and fatty acids composition, SP has become an important alternative feed ingredient and source of EFA. SP is a by-product that was discarded in large quantities. Following the need to act to improve human health and reduce climate change impact, many researchers focused on studying SP applications in the medical and agricultural industries. Several authors noticed an improvement in the health markers by using SP. The feed cost for the animal was reduced with economic implications. Minimization of environmental impact was recorded. Few precautions were recommended regarding SP use, although they should not be ignored. The composition of SP and its potential for use in various industries provides us with persuasive arguments for continuing to develop the sericulture industry. Full article

Melanin has been reported to have potential applications in industries such as cosmetics and food due to its anti-UV and antioxidative qualities. However, the corresponding data on its safety evaluation or biological consequences are fairly limited; such data are critical given its widespread use. The effect of different concentrations (1, 2, 3, and 4%) of melanin on growth status (larvae length and weight, cocoon weight, and morphology), the microstructure of the various tissues (fat body, silk gland, and midgut), and silk properties was studied by using the silkworm (bombyx mori) as the model organism. The weight and length of silkworm larvae fed with melanin were lower than the control, indicating that melanin appears to have a negative effect on the growth status of silkworms; however, the histophysiology analysis indicates that the cell morphologies are not changed, the XRD and FTIR spectra indicate that the secondary and crystalline structures of silks are also well preserved, and the thermogravimetric analysis and tensile test indicate that the thermal stability and mechanical properties are well maintained and even improved to some extent. Generally, it indicates that melanin has a certain inhibitory effect on the growth of silkworm larva but causes no harm to the cell microstructures or silk properties; this demonstrates that the safety of melanin as a food addictive should be considered seriously. The increase of thermal stability and mechanical properties shows that melanin may be a good chemical modifier in textile industries. Full article

As one of the most widespread groups of Gram–negative bacteria, Pseudomonas bacteria are prevalent in almost all natural environments, where they have developed intimate associations with plants and animals. Pseudomonas fulva is a novel species of Pseudomonas with clinical, animal, and plant–associated isolates, closely related to human and animal health, plant growth, and bioremediation. Although genetic manipulations have been proven as powerful tools for understanding bacterial biological and biochemical characteristics and the evolutionary origins, native isolates are often difficult to genetically manipulate, thereby making it a time–consuming and laborious endeavor. Here, by using the CRISPR–Cas system, a versatile gene–editing tool with a two–plasmid strategy was developed for a native P. fulva strain isolated from the model organism silkworm (Bombyx mori) gut. We harmonized and detailed the experimental setup and clarified the optimal conditions for bacteria transformation, competent cell preparation, and higher editing efficiency. Furthermore, we provided some case studies, testing and validating this approach. An antibiotic–related gene, oqxB, was knocked out, resulting in the slow growth of the P. fulva deletion mutant in LB containing chloramphenicol. Fusion constructs with knocked–in gfp exhibited intense fluorescence. Altogether, the successful construction and application of new genetic editing approaches gave us more powerful tools to investigate the functionalities of the novel Pseudomonas species. Full article

The silk-spinning and Lepidopteran model insect Bombyx mori (Bombycidae) is a mulberry specialist. The BmSuc1 gene is the first β-fructofuranosidase (β-FFase) encoding gene identified in animals, and β-FFase acts as an essential sucrase for glycometabolism modulation in the silkworm larvae, involved in resistance to mulberry alkaloids. Glyphodes pyloalis Walker (Lepidoptera: Pyralidae) is an important mulberry pest leading to heavy economic loss of sericulture. However, no molecular or biochemical information is available about G. pyloalis β-FFase homologs. In this study, five β-FFase homologous genes in G. pyloalis were obtained. The genes GpSuc1a and GpSuc2c were expressed in the midgut; GpSuc2c encodes a truncated polypeptide. The expression and the localization of GpSUC1a in the midgut was characterized. Whereas recombinant GpSUC1a expressed in both Escherichia coli and BmN cells displayed little activity as compared with higher activity of BmSUC1, β-FFase activity in the larval midgut of G. pyloalis and GpSUC1a purified from the midgut were both confirmed. The data suggested that the activation of GpSUC1a is probably controlled by a more complicated post-translational regulation system in G. pyloalis larvae than that of BmSUC1 in B. mori. To study post-translational modifications (PTMs), GpSUC1a and BmSUC1 were purified from larval midguts using immunoprecipitation and subjected to LC-MS to perform PTMs analysis. Some putative N-glycosylated sites were found in GpSUC1a but none in BmSUC1, while there was more methylation in BmSUC1 than in GpSUC1a, indicating that such PTMs were supporting the differential β-FFases activities in these two mulberry feeding caterpillars. Full article

Sericulture generates different natural products with potential medical applications. Silk peptides, worms, or even pupae are commonly employed in traditional Asian medicine with a wide variety of purposes, and some scientific work has been focused on their antidiabetic properties. This work evaluates the postprandial antihyperglycemic activity of fibroin, sericin, and powder made from either larvae or pupae of silkworms, and Bombyx mori L. (Lepidoptera: Bombycidae), employing the silkworm itself as an animal model. The results indicate a reduction in the glucose levels in hemolymph after sucrose or glucose-induced hyperglycemia when these products are included in the diet of the worms. Full article

Mucormycosis, a rare but highly fatal infection, is caused by fungi of the order Mucorales. Due to their ubiquitous nature, reduced susceptibility to antifungals, acid tolerance, and ability to infect immunocompromised patients through rapid dissemination, these fungi have been frequently reported to infect the COVID-19 patients. In order to develop strategies to overcome mucormycosis, it is essential to understand and identify novel Mucorales present in the environment. In this study, we report the identification of four novel pathogenic Mucorales using the silkworm (Bombyx mori) model. The strains’ phylogeny was analyzed using the genome sequence of the large subunit ribosomal ribonucleic acid (LSU rRNA) and the internal transcribed spacer (ITS) region, where strains 1-3, 5-3, and S286-1101 claded with Mucor orantomantidis, and strain 827-14 claded with Backusella lamprospora. All the strains had a cold-sensitive phenotype with their inability to grow prominently at 4 °C. Mucor sp. 1-3 and 5-3 were characterized by their filamentous and yeast-like growth under aerobic and anaerobic conditions, respectively. The yeast colonies of Mucor sp. 5-3 had multipolar budding cells often observed with cleaved cell surfaces under a scanning electron microscope. We further found that these strains were able to kill immunocompromised mice suggesting their pathogenicity to mammals. Our study established an invertebrate model-based screening system to identify novel pathogenic Mucorales from the natural environment and provided a clue towards the rapid increase in COVID-19 related mucormycosis. Full article