Acute toxicity of Zinc Oxide nanoparticles to silkworm (Bombyx mori L.)

Comprehensive toxicity assessment of nanodiamond on Blaps polychresta: implications and novel findings

With the increasing development of nanomaterials, the use of nanodiamonds (NDs) has been broadly manifested in many applications. However, their high penetration into the ecosystem indubitably poses remarkable toxicological risks. This paper investigates the toxic effects of NDs on the darkling beetle, Blaps polychresta Forskal, 1775 (Coleoptera: Tenebrionidae). Survival analysis was carried out by monitoring the beetles for 30 d after the injection of four different doses of NDs. A dose of 10.0 mg NDs/g body weight, causing less than 50% mortality effect, was assigned in the analysis of the different organs of studied beetles, including testis, ovary, and midgut. Structural and ultrastructural analyses were followed using light, TEM, and SEM microscopes. In addition, a variety of stress markers and enzyme activities were assessed using spectrophotometric methods. Furthermore, cell viability and DNA damage were evaluated using cytometry and comet assay, respectively. Compared to the control group, the NDs-treated group was exposed to various abnormalities within all the studied organs as follows. Significant disturbances in enzyme activities were accompanied by an apparent dysregulation in the antioxidant system. The flow cytometry results indicated a substantial decrease of viable cells along with a rise of apoptotic and necrotic cells. The comet assay demonstrated a highly increased level of DNA damage. Likewise, histological analyses accentuated the same findings showing remarkable deformities in the studied organs. Prominently, the research findings substantially contribute for the first time to evaluating the critical effects of NDs on B. polychresta, adopted as the bioindicator in this paper.

In Vivo Efficacy of a Nanoconjugated Glycopeptide Antibiotic in Silkworm Larvae Infected by Staphylococcus aureus

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.

Green Synthesis, Characterization and Pharmaceutical Applications of Biocompatible Zinc Oxide Nanoparticles Using Heliotropium rariflorum Stocks

Background: Zinc oxide nanoparticles are safe, non-toxic, and biocompatible. These NPs are used in food packaging materials, self-cleaning glass, ceramics, deodorants, sunscreens, paints, coatings, ointments, lotions, and as preservatives. This study explored the biological potential of ZnO nanoparticles synthesized using H. rariflorum. Methods: In vitro antibacterial and antifungal activities against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Candida albicans, Penicillium notatum, Aspergillus flavus, Aspergillus niger and Aspergillus solani were determined. Antioxidant activity was explored using the DPPH radical scavenging method. In vivo analgesic, antipyretic and sedative potential of synthesized nanoparticles was investigated using a mouse model. Results: SEM with various magnification powers showed that some particles were spherical while some were aggregated, flake-shaped, and hexagonal with rough and irregular surfaces. The EDX analysis revealed Zn (12.63%), O (22.83%) and C (63.11%) with trace quantities of Si (0.40%), Ca (0.54%) and P (0.49%). The XRD pattern indicated an amorphous state, with no peaks observed throughout the spectrum. The UV-visible spectrophotometry revealed a characteristic absorption peak at 375 nm, indicating the presence of ZnO nanoparticles. Fourier Transform Infrared Spectroscopy (FTIR) displayed several small peaks between 1793 and 2370 cm-1, providing evidence of the presence of different kinds of organic compounds with different functional groups. ZnO-NPs showed dose-dependent antibacterial and antifungal potential against all strains. Staphylococcus aureus and Candida albicans were the most susceptible strains. The nanoparticles exhibited a maximum antioxidant effect of 85.28% at 100 μg/mL. In this study, the acute toxicity test showed no mortality, and normal behavior was observed in mice at ZnO-NP doses of 5, 10, and 20 mg/kg. For analgesic and antipyretic activities, a two-way ANOVA revealed that dose, time, and the interaction between dose and time were significant. In contrast, the samples had a non-significant effect on sedative activity. Conclusions: This innovative study suggests a potential use of plant resources for managing microbes and treating various diseases, providing a scientific basis for the traditional use of H. rariflorum.

Effect of acute exposure of Hg on physiological parameters and transcriptome expression in silkworms (Bombyx mori)

Mercury (Hg) contamination poses a global threat to the environment, given its elevated ecotoxicity. Herein, we employed the lepidopteran model insect, silkworm (Bombyx mori), to systematically investigate the toxic effects of Hg-stress across its growth and development, histomorphology, antioxidant enzyme activities, and transcriptome responses. High doses of Hg exposure induced evident poisoning symptoms, markedly impeding the growth of silkworm larvae and escalating mortality in a dose-dependent manner. Under Hg exposure, the histomorphology of both the midgut and fat body exhibited impairments. Carboxylesterase (CarE) activity was increased in both midgut and fat body tissues responding to Hg treatment. Conversely, glutathione S-transferase (GST) levels increased in the fat body but decreased in the midgut. The transcriptomic analysis revealed that the response induced by Hg stress involved multiple metabolism processes. Significantly differently expressed genes (DEGs) exhibited strong associations with oxidative phosphorylation, nutrient metabolisms, insect hormone biosynthesis, lysosome, ribosome biogenesis in eukaryotes, and ribosome pathways in the midgut or the fat body. The findings implied that exposure to Hg might induce the oxidative stress response, attempting to compensate for impaired metabolism. Concurrently, disruptions in nutrient metabolism and insect hormone activity might hinder growth and development, leading to immune dysfunction in silkworms. These insights significantly advance our theoretical understanding of the potential mechanisms underlying Hg toxicity in invertebrate organisms.

Oxidative stress and potential effects of metal nanoparticles: A review of biocompatibility and toxicity concerns

Metal nanoparticles (M-NPs) have garnered significant attention due to their unique properties, driving diverse applications across packaging, biomedicine, electronics, and environmental remediation. However, the potential health risks associated with M-NPs must not be disregarded. M-NPs' ability to accumulate in organs and traverse the blood-brain barrier poses potential health threats to animals, humans, and the environment. The interaction between M-NPs and various cellular components, including DNA, multiple proteins, and mitochondria, triggers the production of reactive oxygen species (ROS), influencing several cellular activities. These interactions have been linked to various effects, such as protein alterations, the buildup of M-NPs in the Golgi apparatus, heightened lysosomal hydrolases, mitochondrial dysfunction, apoptosis, cell membrane impairment, cytoplasmic disruption, and fluctuations in ATP levels. Despite the evident advantages M-NPs offer in diverse applications, gaps in understanding their biocompatibility and toxicity necessitate further research. This review provides an updated assessment of M-NPs' pros and cons across different applications, emphasizing associated hazards and potential toxicity. To ensure the responsible and safe use of M-NPs, comprehensive research is conducted to fully grasp the potential impact of these nanoparticles on both human health and the environment. By delving into their intricate interactions with biological systems, we can navigate the delicate balance between harnessing the benefits of M-NPs and minimizing potential risks. Further exploration will pave the way for informed decision-making, leading to the conscientious development of these nanomaterials and safeguarding the well-being of society and the environment.

Antibacterial Activity of ZnO Nanoparticles in a Staphylococcus-aureus-Infected Galleria mellonella Model Is Tuned by Different Apple-Derived Phytocargos

This research investigates pH changes during the green synthesis of ZnO nanoparticles (NPs) and emphasises its importance in their physicochemical, antibacterial, and biological properties. Varying the synthesis pH from 8 to 12 using "Bravo de Esmolfe" apple extracts neither affected the morphology nor crystallinity of ZnO but impacted NP phytochemical loads. This difference is because alkaline hydrolysis of phytochemicals occurred with increasing pH, resulting in BE-ZnO with distinct phytocargos. To determine the toxicity of BE-ZnO NPs, Galleria mellonella was used as an alternative to non-rodent models. These assays showed no adverse effects on larvae up to a concentration of 200 mg/kg and that NPs excess was relieved by faeces and silk fibres. This was evaluated by utilising fluorescence-lifetime imaging microscopy (FLIM) to track NPs' intrinsic fluorescence. The antibacterial efficacy against Staphylococcus aureus was higher for BE-ZnO12 than for BE-ZnO8; however, a different trend was attained in an in vivo infection model. This result may be related to NPs' residence in larvae haemocytes, modulated by their phytocargos. This research demonstrates, for the first time, the potential of green synthesis to modulate the biosafety and antibacterial activity of NPs in an advanced G. mellonella infection model. These findings support future strategies to overcome antimicrobial resistance by utilizing distinct phytocargos to modulate NPs' action over time.

Synthesis of an Environmentally Friendly Modified Mulberry Branch-Derived Biochar Composite: High Degradation Efficiency of BPA and Mitigation of Toxicity in Silkworm Larvae

In the present study, mulberry branch-derived biochar CuO (MBC/CuO) composite was successfully synthesized and used as a catalyst to activate persulfate (PS) for the degradation of bisphenol A (BPA). The MBC/CuO/PS system exhibited a high degradation efficiency (93%) of BPA, under the conditions of 0.1 g/L MBC/CuO, 1.0 mM PS, 10 mg/L BPA. Free radical quenching and electron spin-resonance spectroscopy (ESR) experiments confirmed that both free radicals ^•OH, SO₄^•- and O₂^•- and non-radicals ¹O₂ were involved in the MBC/CuO reaction system. Cl^- and NOM displayed negligible influence on the degradation of BPA, while HCO₃^- promoted the removal of BPA. In addition, the toxicity tests of BPA, MBC/CuO and the degraded BPA solution were conducted by the 5th instar silkworm larvae. The toxicity of BPA was reduced after the treatment in the MBC/CuO/PS system, and no obvious toxicity of the synthesized MBC/CuO composite was found in the toxicity evaluation experiments. This work provides a new value-added utilization of mulberry branches as a cost-effective and environmentally friendly PS activator.

An in-vivo microfluidic assay reveals cardiac toxicity of heavy metals and the protective effect of metal responsive transcription factor (MTF-1) in Drosophila model

Previous toxicity assessments of heavy metals on Drosophila are limited to investigating the survival, development rate, and climbing behaviour by oral administration while cardiac toxicity of these elements have not been investigated. We utilized a microfluidic device to inject known dosages of zinc (Zn) or cadmium (Cd) into the larvae's hemolymph to expose their heart directly and study their heart rate and arrhythmicity. The effect of heart-specific overexpression of metal responsive transcription factor (MTF-1) on different heartbeat parameters and survival of Drosophila larvae was investigated. The heart rate of wild-type larvae decreased by 24.8% or increased by 11.9%, 15 min after injection of 40 nL of 100 mM Zn or 10 mM Cd solution, respectively. The arrhythmicity index of wild-type larvae increased by 58.2% or 76.8%, after injection of Zn or Cd, respectively. MTF-1 heart overexpression ameliorated these effects completely. Moreover, it increased larvae's survival to pupal and adulthood stages and prolonged the longevity of flies injected with Zn and Cd. Our microfluidic-based cardiac toxicity assay illustrated that heart is an acute target of heavy metals toxicity, and MTF-1 overexpression in this tissue can ameliorate cardiac toxicity of Zn and Cd. The method can be used for cardiotoxicity assays with other pollutants in the future.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03336-7.

Metabolic response of earthworms (Pheretima guillemi) to silver nanoparticles in sludge-amended soil

Silver nanoparticles (AgNPs) can enter soils via the application of sludge and pose risks to soil invertebrates. However, current knowledge regarding the toxicity of AgNPs at environmentally relevant concentration is insufficient, especially at the molecular level. Therefore, we examined the effects of low-level AgNPs (7.2 mg kg^-1, dry weight) on the bioaccumulation, pathology and metabolism of earthworms (Pheretima guillemi). After exposure for 28 d, earthworms were dissected into digestive system and the rest of the body to explore the response of different body parts to AgNPs. Ag concentration in the digestive system of exposed group (2.5 mg kg^-1, dry weight) was significantly higher than that of the control group (0.5 mg kg^-1, dry weight). AgNPs exposure had no significant effects on the survival and growth, but induced intestinal damage and metabolic interference to earthworms relative to the control. Metabolomics analysis showed that AgNPs exposure disturbed the glycerophospholipid metabolism, glutathione metabolism and energy metabolism in the digestive system and the energy metabolism in the rest of the body. AgNPs exposure also induced lipid peroxidation in the digestive system. The different metabolic responses between two body parts highlighted the importance of the uptake routes of Ag. These results provide a biochemical insight for the risk assessment of low-level AgNPs in terrestrial environment.

Dietary exposure of copper and zinc oxides nanoparticles affect the fitness, enzyme activity, and microbial community of the model insect, silkworm Bombyx mori

Copper and Zinc oxides nanoparticles (CuO and ZnO NPs, respectively) are among the most produced and commonly used engineered nanomaterials. They can be released into the environment, thereby causing health concerns and risks to biodiversity that indicate a need to evaluate their toxicological effects in a complex situation. Here, we used the insect model organism silkworm Bombyx mori to address the concerns about the biological effects associated with dietary exposure of CuO and ZnO NPs. ICP-MS analysis revealed significant accumulation of Cu and Zn (the latter being more accumulated) in silkworms' tissues (gut, fat body, silk gland, and malpighian tubule), and some elimination through feces in the respective NPs-exposed groups. NPs-exposures led to a decrease in larval body mass, survivorship, and cocoon production, where the effects of ZnO NPs were more pronounced. We also found that NPs-exposure induced gene expression changes (Attacin, lysozyme, SOD, and Dronc) and altered the activities of antioxidant enzymes (SOD, GST, and CAT), as well as impaired nutrient metabolism (alpha-amylase). Given their antibacterial property, CuO and ZnO NPs decreased species richness and diversity of the gut bacterial community and shifted their configuration to overt microbiome i.e., decreased abundance of probiotics (e.g., Acetobacter) and increased pathobionts (e.g., Pseudomonas, Bacillus, Escherichia, Enterococcus, Ralstonia, etc.) proportions. Overall, this integrated study revealed the unintended negative effects of CuO and ZnO NPs on silkworms and highlighted the potential to inevitably affect all living things due to intensive and possible mishandling of nanomaterials.

Advances in Editing Silkworms (Bombyx mori) Genome by Using the CRISPR-Cas System

CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) represents a powerful genome editing technology that revolutionized in a short period of time numerous natural sciences branches. Therefore, extraordinary progress was made in various fields, such as entomology or biotechnology. Bombyx mori is one of the most important insects, not only for the sericulture industry, but for numerous scientific areas. The silkworms play a key role as a model organism, but also as a bioreactor for the recombinant protein production. Nowadays, the CRISPR-Cas genome editing system is frequently used in order to perform gene analyses, to increase the resistance against certain pathogens or as an imaging tool in B. mori. Here, we provide an overview of various studies that made use of CRISPR-Cas for B. mori genome editing, with a focus on emphasizing the high applicability of this system in entomology and biological sciences.

Genomics and proteomics combined analysis revealed the toxicity response of silkworm Bombyx mori to the environmental pathogen Bacillus cereus ZJ-4

Bacterial contamination has caused a major public health problem worldwide. Bacillus cereus is a conditional environmental pathogenic bacteria that can cause food poisoning. Whether environmental pathogens can cause widespread transmission in the insect kingdom is unclear. In this study, a Bacillus cereus ZJ-4 was isolated from the hospital environment of Zhenjiang City, Jiangsu Province, China. It was fatal by injection into the silkworm hemolymph. To investigated the potential toxic factors of ZJ-4 and clarified the toxicity response mechanism of silkworm by the ZJ-4 infection. Then, the whole genome of ZJ-4 was sequenced, and the immune mechanism of silkworm fat body to ZJ-4 pathogen was studied by HE pathological section and proteomics. Bacterial genome sequencing indicated that ZJ-4 had 352 drug resistance genes and 6 virulence genes. After 36 h of subcutaneous puncture with ZJ-4 suspension, the pathological changes were obviously found in HE pathological sections of fat body tissue. Comparative proteomic results indicated that differentially expressed proteins are mainly involved in stress reactions, biological regulation, and innate immunity. The qRT-PCR analysis showed that the expressions of β-GRP, Spaetzle, MyD88, Tube and Dorsal genes in Toll pathway were up-regulated, while Pell and Cactus genes were down-regulated; in the antimicrobial peptide pathway, Glv2, Lzm, Mor, and Leb3 genes were up-regulated, while attacin1 and defensin genes were down-regulated; Sod gene was up-regulated, while Cat gene was down-regulated in the antioxidant pathway; Ldh, Sdh, and Mdh genes were down-regulated in glucose metabolism pathway. These results indicated that ZJ-4 can damage the innate immune pathway of silkworm, and also affect the normal immune function of fat body cells.

Toxic effects of acute exposure to polystyrene microplastics and nanoplastics on the model insect, silkworm Bombyx mori

Microplastics and nanoplastics (MPs and NPs, respectively) are major contaminants of environmental concern due to their potentially detrimental effects on aquatic and terrestrial ecosystems. However, little is known about their potential toxicity in terrestrial organisms. Here, we used the model insect silkworm (Bombyx mori) to evaluate the potential hazardous effects of acute exposure (72 h) to polystyrene (PS) MPs and NPs at physiological, molecular, and biochemical levels as well as their impact on pathogen infection. Our results revealed no significant changes in larval body mass or survival. Nevertheless, exposure led to significant alterations in the expression of immunity-related genes (Cecropin A, Lysozyme, SOD, and GST) and antioxidant-mediated protective response (SOD, GST, and CAT enzymes) which differed in the PS-MP and PS-NP groups. Interestingly, PS-MPs induced a stronger immune response (higher expressions of Lysozyme, SOD, and GST genes along with increased activities of SOD, GST, and CAT enzymes) while the PS-NP response was more that of an inhibitory nature (decreased SOD activity and expression). As a result, upon infection with the natural pathogen Serratia marcescens Bm1, the PS-MP-exposed individuals survived the infection better whereas, PS-NP-exposed individuals exhibited significantly higher mortality. Thus, we infer that PS-MPs/NPs present ecological toxicity, which is closely related to their size, and that their exposure may render the organisms vulnerable or confer resistance to pathogen infections and ecotoxicants. Given the suitability of silkworm as a model organism, this study may promote its application for further investigation of the mechanism of adverse outcome pathways and in studies on bio-nano interactions.

Beauveria bassiana Ribotoxin (BbRib) Induces Silkworm Cell Apoptosis via Activating Ros Stress Response

The BbRib gene participates in the infection process of Beauveria bassiana (B. bassiana). It also helps pathogenic fungi to escape and defeat the insect host immune defense system by regulating the innate immune response. However, model insects are rarely used to study the mechanism of fungal ribosomal toxin protein. In this study, BbRib protein was produced by prokaryotic expression and injected into silkworm (Bombyx mori) larvae. The physiological and biochemical indexes of silkworm were monitored, and the pathological effects of BbRib protein on immune tissues of silkworm were examined by Hematoxylin and Eosin (HE) staining. BbRib protein can significantly affect the growth and development of the silkworm, causing poisoning, destroying the midgut and fat body and producing physiological changes. The ROS stress response in the adipose tissue and cells of the silkworm was activated to induce apoptosis. These results indicated that the BbRib gene not only participates in the infection process of B. bassiana, it also helps the pathogenic fungi escape the immune system by regulating the innate immune system of the silkworm, allowing it to break through the silkworm’s immune defense. This study reveals the potential molecular mechanism of BbRib protein to insect toxicity, and provides a theoretical basis and material basis for the development and use of novel insecticidal toxins.

A review on the biological effects of nanomaterials on silkworm (Bombyx mori)

The production of high-quality silkworm silk is of importance in sericulture in addition to the production of biomass, silk proteins, and animal feed. The distinctive properties of nanomaterials have the potential to improve the development of various sectors including medicine, cosmetics, and agriculture. The application of nanotechnology in sericulture not only improves the survival rate of the silkworm, promotes the growth and development of silkworm, but also improves the quality of silk fiber. Despite the positive contributions of nanomaterials, there are a few concerns regarding the safety of their application to the environment, in humans, and in experimental models. Some studies have shown that some nanomaterials exhibit toxicity to tissues and organs of the silkworm, while other nanomaterials exhibit therapeutic properties. This review summarizes some reports on the biological effects of nanomaterials on silkworm and how the application of nanomaterials improves sericulture.

Research progress on the carcinogenicity of metal nanomaterials

With the rapid development of nanotechnology, new nanomaterials with enormous potentials continue to emerge, especially metal nanomaterials. Metal nanomaterials possess the characteristics of metals and nanomaterials, so they are widely used in many fields. But at the same time, whether the use or release of metal nan4omaterials into the environment is toxic to human beings and animals has now attained widespread attention at home and abroad. Currently, it is an indisputable fact that cancer ranks among the top causes of death among residents worldwide. The properties of causing DNA damage and mutations possessed by these metal nanomaterials make them unpredictable influences in the body, subsequently leading to genotoxicity and carcinogenicity. Due to the increasing evidence of their roles in carcinogenicity, this article reviews the toxicological and carcinogenic effects of metal nanomaterials, including nano-metal elements (nickel nanoparticles, silver nanoparticles, and cobalt nanoparticles) and nano-metal oxides (titanium dioxide nanoparticles, silica nanoparticles, zinc oxide nanoparticles, and alumina nanoparticles). This article provides a reference for the researchers and policymakers to use metal nanomaterials rationally in modern industries and biomedicine.