Ortho-Vanillin Ameliorates Spinetoram-Induced Oxidative Stress in the Silkworm Bombyx mori: Biochemical and In Silico Insights.

This study investigates the toxic effects of the insecticide spinetoram on the model organism Bombyx mori (Linnaeus) and explores the potential ameliorative properties of O-Vanillin. Sub-lethal concentrations of spinetoram were given to silkworm larvae via oral feed, resulting in reduced body weight, larval length, and impaired cocoon characteristics. A study of the enzymatic and non-enzymatic antioxidants revealed oxidative stress in the gut, fat body, and silk gland tissues, characterized by decreased antioxidants and increased lipid peroxidation. However, post-treatment with O-Vanillin effectively mitigated these toxic effects, preserving antioxidant capacities and preventing lipid peroxidation. Additionally, O-Vanillin prevented the loss of body weight and improved cocoon characteristics. At the histological level, spinetoram exposure caused mild histological damage in the gut, fat body, and silk gland. However, O-Vanillin post-treatment had ameliorative effects and mitigated the histological damages. To delve deeper into the mechanism of amelioration of O-Vanillin, in silico studies were used to study the interaction between an important xenobiotic metabolism protein of the Bombyx mori, i.e., Cytochrome p450, specifically CYP9A19, and O-Vanillin. We performed blind molecular docking followed by molecular dynamic simulation, and the results demonstrated stable binding interactions between O-Vanillin and CYP9A19, a cytochrome P450 protein in silkworm, belonging to the subfamily CYP9A, suggesting a potential role for O-vanillin in modulating xenobiotic metabolism.

Isolation and characterization of bacteria associated with silkworm gut under antibiotic-treated larval feeding / Isolamento e caracterização de bactérias associadas ao trato intestinal do bicho-da-seda sob alimentação larval tratada com antibióticos

Abstract The impact of antibiotics on growth, cocoon production was assessed in addition to isolation and characterization of bacteria associated with silkworm gut of infected larvae. Larval rearing was maintained at recommended conditions of temperature and humidity. Silkworm larvae showing abnormal symptoms were collected from the control group and dissected for gut collection. Bacteria were isolated from the gut content by spreading on agar plates and incubated at 37 °C for 48 hrs. Bacterial identification and phylogenetic analysis were carried out by 16S rRNA gene sequencing. The isolated bacteria were subjected to antimicrobial susceptibility test (disc diffusion methods) by using Penicillin (10 µg/mL), Tetracycline (30 µg/mL), Amoxicillin (25 µg/mL), Ampicillin (10 µg/mL), and Erythromycin (15 µg/mL). All isolated strains showed positive results for the catalase test. We isolated and identified bacterial strains (n = 06) from the gut of healthy and diseased silkworm larvae. Based on the 16S rRNA gene sequence, isolated bacteria showed close relation with Serratia, Bacillus, and Pseudomonas spp. Notably, 83.3% of strains were resistant to Penicillin, Tetracycline, Amoxicillin, Ampicillin, and Erythromycin but 16.6% showed antibiotic susceptibility to the above-mentioned commonly used antibiotics. Silkworm larvae fed on penicillin-treated leaves showed significant improvement in larval weight, larval length, and cocoon production. Significantly higher larval weight (6.88g), larval length (5.84cm), and cocoon weight (1.33g) were recorded for larvae fed on leaves treated with penicillin as compared to other antibiotics. Isolated bacterial strains showed close relation with Serratia spp., Bacillus spp. and Pseudomonas spp.

Resumo O impacto dos antibióticos no crescimento e na produção do casulo foi avaliado, além do isolamento e caracterização das bactérias associadas ao intestino de larvas infectadas do bicho-da-seda. A criação das larvas foi mantida nas condições recomendadas de temperatura e umidade. As larvas do bicho-da-seda com sintomas anormais foram coletadas do grupo controle e dissecadas para coleta do intestino. As bactérias foram isoladas do conteúdo intestinal por espalhamento em placas de ágar e incubadas a 37° C durante 48 horas. A identificação bacteriana e a análise filogenética foram realizadas pelo sequenciamento do gene 16S rRNA. As bactérias isoladas foram submetidas a teste de sensibilidade antimicrobiana (métodos de difusão em disco) com penicilina (10 µg / mL), tetraciclina (30 µg / mL), amoxicilina (25 µg / mL), ampicilina (10 µg / mL) e eritromicina (15 µg / mL). Todas as cepas isoladas apresentaram resultados positivos para o teste da catalase. Isolamos e identificamos cepas bacterianas (n = 06) do intestino de larvas de bicho-da-seda saudáveis e doentes. Com base na sequência do gene 16S rRNA, as bactérias isoladas mostraram estreita relação com Serratia, Bacillus e Pseudomonas spp. Notavelmente, 83,3% das cepas eram resistentes a penicilina, tetraciclina, amoxicilina, ampicilina e eritromicina, mas 16,6% mostraram suscetibilidade aos antibióticos comumente usados mencionados acima. As larvas do bicho-da-seda alimentadas com folhas tratadas com penicilina apresentaram melhora significativa no peso larval, comprimento larval e produção de casulo. Peso larval significativamente maior (6,88g), comprimento larval (5,84cm) e peso do casulo (1,33g) foram registrados para larvas alimentadas com folhas tratadas com penicilina, em comparação com outros antibióticos. Cepas bacterianas isoladas mostraram estreita relação com Serratia spp., Bacillus spp. e Pseudomonas spp.

Composite resin reinforced with silk nanoparticles from Bombyx mori cocoon for dental applications.

The objective of this work was to evaluate the mechanical performance of Z350 resin composite modified with Bombyx mori cocoons silk nanoparticles for dental applications. Four experimental groups were analyzed G0% = Filtek Z350 resin composite (control); G1% = Filtek Z350 with 1% of silk nanoparticles; G3% = Filtek Z350 with 3% of silk nanoparticles; G5% = Filtek Z350 with 5% of silk nanoparticles. It was employed scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, 3-point flexural strength test, Knoop hardness test, and surface roughness. From 3-point flexural strength tests the control group presented the best results G0% = 113.33 MPa (±23.73). The higher flexural modulus was shown by groups G3% = 29.150 GPa (±5.191) and G5% = 34.101 GPa (±7.940), which are statistically similar. The Knoop microhardness test has shown statistical difference only among the G3% group between the top 80.78 (± 3.00) and bottom 68.80 (±3.62) and no difference between the groups. The roughness test presented no statistical difference between the groups. The incorporation of silk nanoparticles reduced the flexural strength of Z350 resin composite. The surface roughness and microhardness tests showed no changes in any of the groups studied.

Effect of environmental conditions on the changes of voltinism in three lines of Bombyx mori.

This work aims to estimate the voltinism differences in the studied lines and the influence of biological and environmental variables on this trait. Three Bombyx mori. lines were used. One polyvoltine (Indian, C. Nichi) and two bivoltine (Chinese6-C6 and Japanese7-J7). Silkworms were reared under controlled conditions of temperature (24±1, 26±1, 28±1°C) and photoperiod (8-16, 12-12, 16-8 light/darkness) during the life cycle. The measured biological characters were duration of larval period (DLP), larval weight on fifth day of V instar (LW(V-5)), rate of weight (RWV), duration of life cycle (DLC), fecunditiy (NE), fertility (F) and voltinism (V). Voltinism was estimated using a linear regression model; the variables that influence voltinism were found using a multiple regression analysis; and the effect of environmental conditions on change of voltinism employing an ANOVA. The results show that the variables that affect voltinism are different for each line, which demonstrates the effect of the line factor. Nichi voltinism was affected by the six measured variables, while in C6 and J7 where voltinisms depends on the duration of diapause, some variables were excluded from the model. In Indian tropical polyvoltine, the temperature was the influencing factor, while in Chinese and Japanese bivoltines lines was the photoperiod.

Lactobacillus for ribosome peptide editing cancer.

This study reviews newly discovered insect peptide point mutations as new possible cancer research targets. To interpret newly discovered peptide point mutations in insects as new possible cancer research targets, we focused on the numerous peptide changes found in the 'CSP' family on the sex pheromone gland of the female silkworm moth Bombyx mori. We predict that the Bombyx peptide modifications will have a significant effect on cancer CUP (cancers of unknown primary) therapy and that bacterial peptide editing techniques, specifically Lactobacillus combined to CRISPR, will be used to regulate ribosomes and treat cancer in humans.

Evaluation of chitosan and silver nanoparticles Against isolated pathogens from Mulberry Silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) under laboratory conditions.

This study aims to isolate and identify certain bactеrial and fungal pathogеns from silkworm, Bombyx mori L. such as promising chitosan, plus silvеr nanoparticlеs as its antimicrobial activity undеr laboratory condition. Silkworm, B. mori (H1xKKxG2xV2-Bolgaria) eggs werе attained from Sеriculture Rеsearch Cеntеr from Giza Governorate, Egypt. Chitosan and silvеr nanoparticlеs matеrials were assembled at the laboratory of Biochеmistry Departmеnt, Faculty of Agriculturе, Al-Azhar University, Cairo, Egypt. Herein total of 7 bactеrial and 5 fungal were isolatеd from the еxtеrnal and internal silkworm larvae. As a result, the mean percentage decrease in weight was elevated in diseased fifth instars (88%) compared to fourth diseased instars (62%). In addition, two bactеrial spеcies isolatеd from the infectеd larvae were identified as follows: Staphylococcus aurеus and Enterococcus faеcalis, whereas thrее fungal spеcies were isolatеd as follows: Aspergillus flavus, Aspergillus tamarii and Beauveria bassiana. Transmission elеctron microscopе imaging demonstrated the morphological propеrties and surfacе appеarance of silvеr and chitosan nanoparticlеs which havе a nеarly sphеrical shapе and smooth surfacе. The avеrage particlе size of 18.7 - 26.0 nm and 18.8 to 21.8 nm of silvеr and chitosan nanoparticles were recordеd. Furthermore, the highеst activity among nanoparticlеs tested against all pathogеnic bacteria and fungi isolatеd and idеntified in our study was rеcordеd by chitosan at 100 µg/ml in sеries, whilst silvеr nanoparticle еxhibitеd modеrate antibacterial and antifungal activity.

Effect of chemical dechorionation on silkworm embryo viability.

The chorion covering/protecting insect egg, which has some effective functions such as providing mechanical strength, protecting eggs from external environments, and keeping moisture adjustment, is one of the principal barriers to manipulation, cryopreservation, and study of insect embryos. Here we evaluated the silkworm embryo viability after dechorionation using chemical reagents. We have developed an easy and effective method for chemical dechorionation that enables embryos to develop in culture, so that the larvae could normally grow. Eggs attached to a nylon net were treated with potassium hydroxide (KOH) and sodium hypochlorite (NaClO) to remove the chorion, washed with the Grace's insect medium, and then cultured using a dry-moist method which we created. The most effective treatment with regard to embryonic development, hatching, and production of second instar larvae was 30% KOH for 7 min and 2% NaClO for 5 min at 27 °C. Embryos at later embryonic stages were more tolerant to chemical dechorionation and over 75% of embryos treated at 168 h-old (Stage 25, appearance of taenidium) survived to the second larval instar, moreover, the larvae derived from the dechorionated embryos have developed into the moths which can lay the fertilized eggs. Our method would contribute to the establishment of cryopreservation using embryos and analysis of silkworm embryogenesis and might also be applicable to other insect species.

Genetic parameters in traits of productive importance in lines of Bombyx mori L.

In the textile industry, complex cocoon traits are closely related to silk production. The aim of the present study was to estimate genetic parameters of economic importance traits-cocoon length (CL), cocoon weight (CW) and shell weight (SW)-in three B. mori lines-Chinese (C6), Japanese (J7) and Indian (C. Nichi)-reared under different temperature and photoperiod conditions. For each of these lines, data were collected from several generations with a full-sibling family structure and variance-covariance component were obtained via restricted maximum likelihood (REML) estimates based on a bi-trait animal model analysed through the multiple-trait derivative-free restricted maximum likelihood (MTDFREML) software. Genetic parameters of the traits varied between the silkworm lines were evaluated. Heritabilities were highest in J7 line (0.71, 0.89 and 0.93 for CL, CW and SW, respectively) followed by C6 (0.48, 0.54 and 0.50 for CL, CW and SW, respectively) and C. Nichi (0.36, 0.43 and 0.40 for CL, CW and SW, respectively). Phenotypic correlations among these lines were positive, with values ranging between 0.36 and 0.767. Similarly, genetic correlations between the analysed silkworm lines were observed to be positive, with high values ranging from 0.86 to 0.94. The evidence for environmental correlation in these lines was found only between CW-SW traits with moderate to high values ranging from 0.600 to 0.940. The magnitude of heritability and genetic correlations implies that phenotypic variations of the CL, CW and SW traits depend mainly on genotypic variation within the J7, C6 and C. Nichi lines, and that simultaneous genetic gains are possible by implementing selection processes for any of the evaluated traits.

Evaluation of chitosan and silver nanoparticles Against isolated pathogens from Mulberry Silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) under laboratory conditions / Avaliação de nanopartículas de quitosana e prata contra patógenos isolados de bicho-da-seda, Bombyx mori L. (Lepidoptera: Bombycidae), em condições de laboratório

This study aims to isolate and identify certain bactеrial and fungal pathogеns from silkworm, Bombyx mori L. such as promising chitosan, plus silvеr nanoparticlеs as its antimicrobial activity undеr laboratory condition. Silkworm, B. mori (H1xKKxG2xV2-Bolgaria) eggs werе attained from Sеriculture Rеsearch Cеntеr from Giza Governorate, Egypt. Chitosan and silvеr nanoparticlеs matеrials were assembled at the laboratory of Biochеmistry Departmеnt, Faculty of Agriculturе, Al-Azhar University, Cairo, Egypt. Herein total of 7 bactеrial and 5 fungal were isolatеd from the еxtеrnal and internal silkworm larvae. As a result, the mean percentage decrease in weight was elevated in diseased fifth instars (88%) compared to fourth diseased instars (62%). In addition, two bactеrial spеcies isolatеd from the infectеd larvae were identified as follows: Staphylococcus aurеus and Enterococcus faеcalis, whereas thrее fungal spеcies were isolatеd as follows: Aspergillus flavus, Aspergillus tamarii and Beauveria bassiana. Transmission elеctron microscopе imaging demonstrated the morphological propеrties and surfacе appеarance of silvеr and chitosan nanoparticlеs which havе a nеarly sphеrical shapе and smooth surfacе. The avеrage particlе size of 18.7 - 26.0 nm and 18.8 to 21.8 nm of silvеr and chitosan nanoparticles were recordеd. Furthermore, the highеst activity among nanoparticlеs tested against all pathogеnic bacteria and fungi isolatеd and idеntified in our study was rеcordеd by chitosan at 100 µg/ml in sеries, whilst silvеr nanoparticle еxhibitеd modеrate antibacterial and antifungal activity.

Este estudo visa isolar e identificar certos patógenos bacterianos e fúngicos do bicho-da-seda (Bombyx mori L.), como a promissora quitosana, além de nanopartículas de prata como sua atividade antimicrobiana em condições de laboratório. Ovos de B. mori (H1xKKxG2xV2-Bolgaria) foram obtidos do Centro de Pesquisa em Sericultura da Província de Gizé, Egito. Materiais de nanopartículas de quitosana e prata foram montados no laboratório do Departamento de Bioquímica, Faculdade de Agricultura, Universidade Al-Azhar, Cairo, Egito. Aqui, foi isolado um total de 7 bactérias e 5 fungos das larvas de bicho-da-seda externas e internas. Como resultado, a diminuição percentual média no peso foi elevada no quinto instar doente (88%) em comparação com o quarto instar doente (62%). Além disso, foram identificadas duas espécies bacterianas isoladas das larvas infectadas (Staphylococcus aureus e Enterococcus faecalis), enquanto três espécies fúngicas foram isoladas (Aspergillus flavus, Aspergillus tamarii e Beauveria bassiana). A imagem de microscopia eletrônica de transmissão demonstrou as propriedades morfológicas e aparência de superfície de nanopartículas de prata e quitosana que têm uma forma quase esférica e superfície lisa. Foi registrado o tamanho médio das partículas de 18,7-26,0 nm e 18,8-21,8 nm de nanopartículas de prata e quitosana, respectivamente. Além disso, a atividade mais alta entre as nanopartículas testadas contra todas as bactérias patogênicas e fungos isolados e identificados em nosso estudo foi registrada pela quitosana em 100 µg/ml em série, enquanto a nanopartícula de prata exibiu atividade antibacteriana e antifúngica moderada.

Isolation and characterization of bacteria associated with silkworm gut under antibiotic-treated larval feeding.

The impact of antibiotics on growth, cocoon production was assessed in addition to isolation and characterization of bacteria associated with silkworm gut of infected larvae. Larval rearing was maintained at recommended conditions of temperature and humidity. Silkworm larvae showing abnormal symptoms were collected from the control group and dissected for gut collection. Bacteria were isolated from the gut content by spreading on agar plates and incubated at 37 °C for 48 hrs. Bacterial identification and phylogenetic analysis were carried out by 16S rRNA gene sequencing. The isolated bacteria were subjected to antimicrobial susceptibility test (disc diffusion methods) by using Penicillin (10 µg/mL), Tetracycline (30 µg/mL), Amoxicillin (25 µg/mL), Ampicillin (10 µg/mL), and Erythromycin (15 µg/mL). All isolated strains showed positive results for the catalase test. We isolated and identified bacterial strains (n = 06) from the gut of healthy and diseased silkworm larvae. Based on the 16S rRNA gene sequence, isolated bacteria showed close relation with Serratia, Bacillus, and Pseudomonas spp. Notably, 83.3% of strains were resistant to Penicillin, Tetracycline, Amoxicillin, Ampicillin, and Erythromycin but 16.6% showed antibiotic susceptibility to the above-mentioned commonly used antibiotics. Silkworm larvae fed on penicillin-treated leaves showed significant improvement in larval weight, larval length, and cocoon production. Significantly higher larval weight (6.88g), larval length (5.84cm), and cocoon weight (1.33g) were recorded for larvae fed on leaves treated with penicillin as compared to other antibiotics. Isolated bacterial strains showed close relation with Serratia spp., Bacillus spp. and Pseudomonas spp.

Morus alba: Host reaction for Meloidogyne javanica, biological nematicides assessment and study of these relationships with yield and quality of leaves, cocoon and health of the silkworm.

Root-knot nematodes cause damage to several crops and the importance of each species can vary according with the crop and the agricultural region. In Brazil, Meloidogyne javanica is one of the most important nematode species parasitizing mulberry. To define management strategies, it is important to know if the crop species is damaged by the parasitism of the nematode and the best choices for control, as the use of nematicides. Biological nematicides have been extensively used in Brazil, but no information regarding its efficiency to control M. javanica in mulberry is available. Besides, it is not known if biological nematicides could improve the quality of leaves or if they alter the nutrient composition of leaves, which could interfere in the development of the silkworms that are feed with these leaves or in the quality of the silk produced. With the aim to address these questions, we propose a study that will start in the phenotyping of the main Brazilian mulberry cultivars to Meloidogyne species, passing through the test of efficiency of biological nematicides in the control of M. javanica in mulberry cultivar Miura, evaluation of the amount and quality of leaves produced and, using these leaves to feed silkworms, in the analyzes of the impact of these diet in the health of silkworms, and in the production and quality of the silk.

Protective effect of Bombyx mori gloverin on intestinal epithelial cells exposure to enterotoxigenic E. coli.

Bombyx mori gloverin A2 (BMGlvA2) is an induced antimicrobial insect protein isolated from Bombyx mori. This study was conducted to explore the effect and potential mechanisms of BMGlvA2 on inflammatory responses and cellular functions in intestinal epithelial cells (IPEC-J2) exposure to enterotoxigenic E. coli (ETEC). IPEC-J2 cells pretreated with or without BMGlvA2 (12.5 µg/mL) were challenged by ETEC K88 (1×106 CFU/well) or culture medium. We show that BMGlvA2 pretreatment increased the cell viability and improved the distribution and abundance of tight junction protein ZO-1 in IPEC-J2 cells exposure to ETEC (P < 0.05). Interestingly, BMGlvA2 not only decreased the expression levels of inflammatory cytokines such as the tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß), but also decreased the expression level of Caspase3 and the apoptosis rate in the ETEC-challenged cells (P < 0.05). Importantly, BMGlvA2 decreased the protein abundances of two critical inflammation-associated signaling proteins, phosphorylated nuclear factor-kappa-B inhibitor alpha (p-IκBα) and phosphorylated nuclear factor-kappa B (p-NF-κB), in the ETEC-challenged cells. These results indicate that BMGlvA2 attenuates ETEC-induced inflammation in the IPEC-J2 cells by regulating the NF-κB signaling pathway, resulting in decreased secretion of inflammatory cytokine and reduced cell apoptosis.

The Wild Silkmoths (Lepidoptera: Bombycoidea: Saturniidae) of Colombia: a database of occurrence points and taxonomic checklist.

Based on the review of literature and biological collections, information retrieved from public online databases, and from fieldwork conducted between 2015 and 2020, we provide more than 3500 occurrence records and an updated checklist of Colombian Saturniidae, annotated with distribution data for all species. In the first checklist of Colombian saturniids published two decades ago, a total of 184 species were cited; in the current update the number has risen to 653 species/subspecies classified in 55 genera, representing all six recognized Neotropical subfamilies. The Andean and Pacific regions are the richest, accounting for about three quarters of all species listed herein. We call attention to the fact that for most speciose saturniid genera in the Neotropics, there remains a significant need for further taxonomic and systematic research with objective and integrative approaches. Likewise, it is necessary to continue the study of Saturniidae moths in Colombia, strategically increasing the sampling efforts in specific under-sampled natural regions to further document the diversity of this family in the country.

Engineering of sustainable biomaterial composites from cellulose and silk fibroin: Fundamentals and applications.

This review addresses composites prepared from cellulose (Cel) and silk fibroin (SF) to generate multifunctional, biocompatible, biodegradable materials such as fibers, films and scaffolds for tissue engineering. First, we discuss briefly the molecular structures of Cel and SF. Their structural features explain why certain solvents, e.g., ionic liquids, inorganic electrolyte solutions dissolve both biopolymers. We discuss the mechanisms of Cel dissolution because in many cases they also apply to (much less studied) SF dissolution. Subsequently, we discuss the fabrication and characterization of Cel/SF composite biomaterials. We show how the composition of these materials beneficially affects their mechanical properties, compared to those of the precursor biopolymers. We also show that Cel/SF materials are excellent and versatile candidates for biomedical applications because of the inherent biocompatibility of their components.

Identification and characterization of three microsporidian genera concurrently infecting a silkworm, Bombyx mori, in Brazil.

Microsporidia are important entomopathogens known for infecting insects such as the silkworm (Bombyx mori) thus impairing global silk production. This study aimed to identify and characterize the microsporidia isolated from a diseased larva of silkworm, collected from a sericulture farm in southern Brazil. Identification was performed by phylogenetic analysis of the nucleotide sequences of the SSU rRNA genes. Characterization was performed by analyzing spore sizes, tissue tropism, internal and external symptoms, and pathogenicity against B. mori. Microsporidia belonging to three different genera were identified, namely, Endoreticulatus, Nosema and Tubulinosema. After inoculation of the mixed spores of the microsporidian isolates into B. mori larvae, a high prevalence of Tubulinosema spp. was observed. This isolate showed high prevalence on the silk glands and a late mortality, initially of around 10% until the 20th day post-inoculation but reaching 91.5% upon pupation. Therefore, we demonstrated that Tubulinosema spp. causes chronic infection with slow pathogenicity. We identified for the first time three different microsporidians concurrently infecting B. mori in Brazil. Tubulinosema is of particular interest because of its potential threat to silk production; it affects the formation of silk glands in B. mori while not presenting distinguishable external symptoms or causing the immediate death of these insects. Further studies focusing on this species, mainly regarding its life cycle within the host and the sublethal effects of surviving individuals, demonstrate the importance of describing it as a new species and improving the characterization of the disease in order to prevent its spread.

Novaluron impairs the silk gland and productive performance of silkworm Bombyx mori (Lepidoptera: Bombycidae) larvae.

This study investigates the effects of the insect growth regulator Novaluron on the silk gland (SG) and silk cocoon production in a nontarget insect, the silkworm Bombyx mori, which is a model research insect among Lepidoptera and of great economic importance for the commercial production of silk threads. Larvae were segregated into experimental groups: the control group (CG) and the treatment group (TG), which was exposed to a Novaluron concentration of 0.15 mL/L. Following exposure, we analyzed the cytotoxic effects on the epithelial cells of the anterior, middle and posterior regions of the SG of B. mori larvae in the 3rd, 4th, and 5th instars, as well as the quality of the cocoons from larvae in the 5th instar. Cytotoxic effects were observed in the TG, such as the dilation of cells, emission of cytoplasmic protrusions, extreme rarefaction of the cytoplasm and nuclei, dilation of the endoplasmic reticulum, intracellular and intercellular spaces, spacing between the epithelial cells and the basal lamina and detachment of some cells towards the lumen of the SG, and decreased protein in the lumen, with faults in its composition. In addition, we verified ultrastructural changes in the production of fibers and silk cocoons, including a reduction in the weight of the cocoons constructed by both males and females in the TG and the construction of defective cocoons. Novaluron exposure impairs the SG and may affect the physiological functions of this organ; additionally, it compromises the quality of silk cocoons, potentially causing serious damage to sericulture.

Interfacial water and its potential role in the function of sericin against biofouling.

Silk sericin is a globular protein whose resistance against fouling is important for applications in biomaterials and water-purification membranes. Here it is shown how sericin generates a water-exclusion zone that may facilitate antifouling behavior. Negatively charged microspheres were used to mimic the surface charge and hydrophobic domains in bacteria. Immersed in water, regenerated silk sericin formed a 100-µm-sized exclusion zone (for micron-size foulants), along with a proton gradient with a decrease of >2 pH-units. Thus, when in contact with sericin, water molecules near the surface restructure to form a physical exclusionary barrier that might prevent biofouling. The decreased pH turns the aqueous medium unviable for neutrophilic bacteria. Therefore, resistance to biofouling seems explainable, among other factors, on the basis of water-exclusionary phenomena. Furthermore, sericin may play a role in triggering the fibroin assembly process by lowering the pH to the required value.

Negative impact of Novaluron on the nontarget insect Bombyx mori (Lepidoptera: Bombycidae).

Due to increased use of agrochemicals and growing concerns about ecotoxicology, the development of new insecticides, moving away from those with neurotoxic and broad spectrum effects towards insecticides that are safer for the environment and nontarget beneficial species, has been a research priority. Novaluron stands out among these newer insecticides, is an insect growth regulator that is used for the control of insect pests in crops grown close to mulberry plantations. Mulberry serves as food for the silkworm Bombyx mori, which is a nontarget insect of great economic importance to silk production. We investigated the lethal and sublethal effects of Novaluron on the development of B. mori. Larvae were segregated into experimental groups: the control groups (CGs) and the treatment groups (TGs), which were treated with the Novaluron concentration of 0.15 mL/L. Following exposure, we analyzed: larval mortality, changes in the insect life cicle and cytotoxic effects on the midgut cells. This is the first report about the Novaluron's effects on B.mori. We detected rupture in the integument, complete cessation of feeding, late development, incomplete ecdysis and production of defective cocoons. After 240 h of exposure, there was 100% mortality in TG larvae exposed in the 3rd instar and 20% mortality from larvae exposed in the 5th instar. Cytotoxic effects was observed, such as dilation of cells, emission of cytoplasmic protrusions, extreme rarefaction of the cytoplasm and nuclei, dilation of the endoplasmic reticulum in addition to changes in mitochondria, the presence of large digestive vacuoles and intercellular spaces and the presence of active caspase. Novaluron exposure impairs the midgut and may affect the physiological functions of this organ. Novaluron additionally compromises several phases of insect development, indicating the importance of toxicology studies that utilize different life stages of nontarget species to evaluate the safe use of insecticides.

Silk fibroin hydrogels from the Colombian silkworm Bombyx mori L: Evaluation of physicochemical properties.

Hydrogel scaffolds are important materials in tissue engineering, and their characterization is essential to determine potential biomedical applications according to their mechanical and structural behavior. In this work, silk fibroin hydrogels were synthesized by two different methods (vortex and sonication), and agarose hydrogels were also obtained for comparison purposes. Samples were characterized by scanning electron microscopy, infrared analysis, thermo-gravimetrical analysis, confined compression test, and rheological test. The results indicate that nanofibers can be obtained via both silk fibroin and agarose hydrogels. The mechanical tests showed that the Young's modulus is similar to those found in the literature, with the highest value for agarose hydrogels. All the hydrogels showed a shear-thinning behavior. Additionally, the MTT test revealed that silk fibroin hydrogels had low cytotoxicity in THP-1 and HEK-293 cells, whereas the agarose hydrogels showed high toxicity for the THP-1 cell line. The results indicate that silk fibroin hydrogels obtained from a Colombian silkworm hybrid are suitable for the development of scaffolds, with potential applications in tissue engineering.

Antioxidant Systems as a Response to Midgut Cellular of Bombyx mori Lineu, 1758 (Lepidoptera: Bombycidae) Infection for Baculoviruses.

Bombyx mori nucleopolyhedrovirus (BmNPV) is a DNA virus that infects different tissues in Bombyx mori at immature stage. Caterpillars become infected after ingesting polyhedral occlusion bodies (POB) present in contaminated mulberry leaves and spread through the body after passing the epithelium of the midgut. As this organ is responsible for digestion, most absorption of nutrients requires an intact epithelium to maintain gastrointestinal physiology. Considering the importance of this organ in the feeding of caterpillars and in the production of quality silk threads, and because it is also the first barrier faced by the BmNPV, the study analyzed details of cytopathological events in the intestinal cells as well as evaluated the action of the antioxidant systems as a response to cellular infection. For this purpose, B. mori hybrid caterpillars of fifth instar were inoculated with a suspension of 7.8 × 107 POB ml-1 and, from the first to the eighth day post-inoculation (dpi), segments of the midgut were collected and processed for light and electronic microscopy. The nuclei of columnar cells showed polyhedric occlusion bodies in the seventh dpi and fragmentation of those cells, with peritrophic matrix disorganization. Analysis of antioxidant systems shows some moments of changes of the catalase enzymes and superoxide dismutase. Analysis of the cholinergic system revealed changes only at the beginning of the infection. Thus, the article acknowledges the antioxidant system as a barrier to stop viral infection, albeit it cannot stop infection from occurring, once a coevolutionary bond is maintained between virus and host.