Tissues Of Silkworm Research Articles

Impact of Surface Functionality on Biodistribution of Gold Nanoparticles in Silkworms

To date, animal models are still indispensable for studying biodistribution and elimination of nanomaterials. However, the use of mammals for in vivo experiments faces various challenges including increasing regulatory hurdles and costs. This study aims to validate larvae of the domestic silkworm Bombyx mori as an alternative invertebrate model for preliminary in vivo research. Organ distribution and elimination of gold nanoparticles (AuNPs) are compared with four different surface functionalities in silkworms after systemic administration: AuNPs coated with poly(ethylene glycol) (PEG), with polyglycidols (PGs) that are slightly hydrophobic (PG(alkyl)), positively charged (PG(+)), or negatively charged (PG(−)). Subsequent inductive coupled plasma mass spectrometry 6 or 24 h after AuNPs administration reveals the biodistribution in silkworm hemolymph, midgut, epidermis, and excrements. Even after 24 h incubation, hemolymph contains the highest AuNPs concentrations, independent of surface functionalization indicating a prolonged circulation time and slow distribution into different silkworm organs and tissues. Positively charged PG(+)AuNPs show three times higher concentrations in the midgut and are excreted at the fastest rate when compared to other AuNPs. In the findings, a surface‐dependent biodistribution and elimination of AuNPs are indicated in silkworms, and the feasibility of using this inexpensive animal model for time‐ and cost‐effective, preliminary in vivo studies of NPs is confirmed.

Relationship between Changes in Intestinal Microorganisms and Effect of High Temperature on the Growth and Development of Bombyx mori Larvae.

Temperature is an important environmental factor affecting the growth and development of silkworm (Bombyx mori). To analyze the effect of intestinal microbes on silkworm in response to a high-temperature environment, this study used a combination of high throughput sequencing and biochemical assays to detect silkworm intestinal microbes treated with high temperature for 72 h. The results show that high temperature affects the intestinal microbes of silkworm and that there are sex differences, specifically, females were more sensitive. The changes in the metabolism and transport ability of silkworm intestinal tissues under high temperature are related to the intestinal microbes. High temperatures may affect the intestinal microbes of silkworms, regulating the activity of related digestive enzymes and substance transport in the intestine, thereby affecting the silkworm’s digestion and absorption of nutrients, and ultimately affecting growth and development.

Proteomic and Targeted Metabolomic Studies on a Silkworm Model of Parkinson's Disease.

Parkinson's disease (PD) is a chronic and progressive movement disorder that is characterized by the loss of dopaminergic neurons in the brain. Animal models of PD have become very popular in the past two decades to understand the etiology, pathology, and molecular and cellular pathways associated with PD. In this study, we report the first neurotoxin-induced silkworm model for PD by chronic feeding with 6-hydroxydopamine (6-OHDA) and explore the possible molecular mechanisms associated with PD using proteomic and targeted metabolomic approaches. Although silkworm is phylogenetically distant from humans and rats, 6-OHDA treatment produced similar PD phenotypes, including motor dysfunction, dopaminergic neuron degeneration, and decreased levels of dopamine. Major neurotransmitters in the silkworm head tissue were profiled, revealing key molecules implicating neurodegenerative disorder. Proteomics analysis revealed a major downregulation of nearly 50 structural proteins constituting cuticles and microfilaments, indicating mechanical damage in the silkworm tissues. The results suggest that 6-OHDA treatment could induce PD-like symptoms in silkworms and activate similar proteomic and metabolic pathways to those in rats or higher animals. This study demonstrates the feasibility and value of the silkworm-based PD model, which may provide important clues for understanding the molecular and cellular mechanisms underlying PD. The mass spectrometry raw files have been deposited to iProx via the project ID IPX0004206000.

Characterization and functional analysis of BmSR-B1 for phytosterol uptake

Insects cannot synthesize sterols, such as cholesterol, and require sterols in their diet. Phytophagous insects use dietary phytosterols as a source of cholesterol. Sterols are transported from the midgut by the insect lipoprotein, lipophorin (Lp), although mechanisms for uptake of phytosterols into tissues are unclear. This study characterizes Scavenger Receptor class B type1 (SR-B1) from Bombyx mori (BmSR-B1) as molecules related to phytosterol uptake. According to sterol quantification using LC-MS/MS analysis, the midgut and fat body were phytosterol-rich relative to cholesterol-rich brain and prothoracic glands. Gene expression analysis of Bmsr-b1 in silkworm tissues showed that the genes Bmsr-b1_2, 3, 4, 6, and 10 were expressed in the midgut and fat body. To characterize the function of BmSR-B1, 11 BmSR-B1 homologs expressed in Bombyx ovary-derived BmN cells and Drosophila melanogaster embryo-derived Schneider 2 (S2) cells were incubated with purified Lp. Our analysis showed that BmSR-B1_3 induced the accumulation of campesterol and BmSR-B1_4 induced the accumulation of β-sitosterol and campesterol in culture cells. BmSR-B1 incorporated specific phytosterols into insect cells by selective uptake across the cell membrane where BmSR-B1 was localized. In conclusion, our study demonstrated that one function of BmSR-B1 is the uptake of phytosterols into silkworm tissues.

5'-Nucleotidase Plays a Key Role in Uric Acid Metabolism of Bombyx mori.

Uric acid (UA) is the end-product in the human purine metabolism pathway. The UA that accumulates in silkworm tissues is excreted as a nitrogen waste product. Here, we first validated that Bombyx mori has a homolog of the human gene that encodes the 5′-nucleotidase (5′N) involved in purine metabolism. The B. mori gene, Bm5′N, is located upstream of other genes involved in UA metabolism in the silkworm. Disruption of Bm5′N via the CRISPR/Cas9 system resulted in decreased UA levels in the silkworm epidermis and caused a translucent skin phenotype. When Bm5′N mutant silkworms were fed with the uric acid precursor inosine, the UA levels in the epidermis increased significantly. Furthermore, the metabolomic and transcriptomic analyses of Bm5′N mutants indicated that loss of the Bm5′N affected purine metabolism and the ABC transport pathway. Taken together, these results suggest that the UA pathway is conserved between the silkworm and humans and that the Bm5′N gene plays a crucial role in the uric acid metabolism of the silkworm. Thus, the silkworm may be a suitable model for the study of UA metabolism pathways relevant to human disease.

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.

Protective effects of pretreatment with Fe2+, Cu2+, and Rb+ on phoxim poisoning in silkworm, Bombyx mori

BackgroundPhoxim is a widely used organophosphorus pesticide in agriculture. People are paying more and more attention to its toxicity. At present, there is no appropriate way to solve the phoxim poisoning of silkworm, which severely affected the development of sericulture. Fe2+, Cu2+, Rb+ exerted their biological effects through various forms in vivo. MethodsTo evaluate the effect of Fe2+/Cu2+/Rb+ on phoxim poisoning in silkworm, Bombyx mori were treated with fresh mulberry leaves soaked in 2.5 mg/L phoxim for 2 min with 50 mg/L FeCl2, 150 mg/L CuCl2, or 0.5 mg/L RbCl from 5 days of the fifth-instar silkworm. ResultsFe2+, Cu2+, and Rb+ pretreatments significantly inhibited the phoxim-induced reduction of survival rate and alleviated the phoxim-induced poisoning symptoms. The protective effects of Fe2+, Cu2+, and Rb+ on phoxim poisoning might be due to their enhancement of superoxide dismutase (SOD), catalase (CAT), and carboxylesterase (CarE) in the hemolymph and fat body of silkworm. This enhancement might reduce reactive oxygen species (ROS) accumulation and oxidative stress (OS) caused by phoxim poisoning. Thereby it reduced the damage to silkworm tissues and cells. ConclusionsThese results showed that Fe2+, Cu2+, and Rb+ treatments protected the silkworm from phoxim poisoning by directly enhancing the activity of SOD, CAT, and CarE enzymes and reducing oxidative stress, but not dependent on the high expression of CYP genes. The use of Fe2+, Cu2+, and Rb+ to enhance the activity of SOD, CAT, and CarE enzymes may be an underlying effective way to solve phoxim poisoning in the silkworm industry.

Function of Polyamines in Regulating Cell Cycle Progression of Cultured Silkworm Cells.

Simple SummaryThe mechanism of the polyamine pathway in the lepidopteran silkworm is largely unknown. In the current study, we aimed to characterize the function of polyamines and polyamine pathway genes in silkworm cells as a regulator of cell cycle progression. For the first time, we identified the homologous genes of the polyamine pathway in silkworm, and analyzed their expression characteristics in different tissues and their subcellular localizations in cultured silkworm cells. We measured the abundant levels of polyamines in silkworm cells by HPLC analysis. We found that exogenous supplementation of spermidine in cells promoted DNA replication and cell cycle progression and, in contrast, treatment with polyamine biosynthesis inhibitors DFMO and MGBG prevented DNA replication and cell cycle progression. Indeed, the mechanism studies indicated that spermidine increased the expression of cell cycle-related genes, whereas this increase could be abolished by treatment with inhibitors. Taken together, our findings highlight that appropriate levels of polyamines have beneficial effects on the progression of the cell cycle by regulating cell cycle genes in silkworm.Background: Putrescine, spermidine, and spermine are polyamines that are ubiquitously distributed in prokaryotic and eukaryotic cells, which play important roles in cell proliferation and differentiation. Methods: We investigated the expression profiles of polyamine pathway genes by qRT-PCR in different tissues of the lepidopteran silkworm. The polyamine levels in cultured silkworm cells were measured by HPLC. Spermidine and polyamine biosynthetic inhibitors were used for treating the cultured silkworm cells in order to clarify their effects on cell cycle progression. Results: We identified the anabolic and catabolic enzymes that are involved in the polyamine biosynthetic pathway in silkworm. Transcriptional expression showed at least seven genes that were expressed in different silkworm tissues. Treatments of the cultured silkworm cells with spermidine or inhibitor mixtures of DFMO and MGBG induced or inhibited the expression of cell cycle-related genes, respectively, and thus led to changed progression of the cell cycle. Conclusions: The present study is the first to identify the polyamine pathway genes and to demonstrate the roles of polyamines on cell cycle progression via regulation of the expression of cell cycle genes in silkworm.

In vivo toxicity evaluation of boron nitride nanosheets in Bombyx mori silkworm model

Boron nitride nanosheets (BN NSs), a novel material with a structure similar to graphene, have attracted much attention due to their extraordinary properties. A deep in vivo study of the toxicity of BN NSs is indispensable, which can help to understand their potential risk and provide useful information for their safe application. However, so far as we know, the systematic in vivo toxicity evaluation of BN NSs hasn’t been reported. In this study, silkworm (Bombyx mori) was used as a model to investigate the toxicity of BN NSs, by continuously feeding silkworm larvae with BN NSs at various mass concentrations (1%, 2%, 3%, 4%). The toxicity was evaluated from the levels of animal entirety (mortality, silkworm growth, cocoons and silk properties), tissues (pathological examination) and genes (transcriptomic profiling). The results show that the exposure to BN NSs causes no obvious adverse effects on the growth, silk properties or tissues of silkworm, but the expressions of genes in midgut concerned with some specific functions and pathways are significantly changed, indicating that BN NSs may have potential danger to lead to dysfunction. This study has performed in vivo toxicity evaluation of BN NSs and provided useful safety information for the application of BN NSs.

Studies on enzymes Superoxide dismutase and Catalase in midgut of Samia ricini under thermal stress condition

In the present study, 5th instar larvae on Samia ricini were subjected into temperature stress (31.2 ± 1°C) every day for 5 hrs till mature stage to assess the enzymes superoxide dismutase (SOD) and catalase (CAT) in midgut tissue of different eco-races of eri silkworm viz., Borduar, Titabar and Mendipathar. Over generation of reactive oxygen species (ROS) can cause midgut cellular damage as a result it might affect the growth and production of eri silkworm. The temperature stress resulted significant increase in the enzyme SOD and CAT which indicated a defence mechanism to protect cellular damage against ROS. The results also showed that ROS level increased significantly under temperature stressed condition, compared with control. The study confirmed that thermal stress can be responsible for cellular damage and to overcome such stress, SOD and CAT play a key role in protecting oxidative damage in midgut tissue of eri silkworm.

Vacuolar protein sorting 4 is required for silkworm metamorphosis.

Vacuolar protein sorting 4 (Vps4) not only functions with its positive regulator vacuolar protein sorting 20-associated 1 (Vta1) in the multivesicular body (MVB) pathway but also participates alone in MVB-unrelated cellular processes. However, its physiological roles at the organism level remain rarely explored. We previously identified their respective homologues Bombyx mori Vps4 (BmVps4) and BmVta1 from the silkworm, a model organism for insect research. In this study, we performed fluorescence quantitative real-time PCR and Western blot to globally characterize the transcription and protein expression profiles of BmVps4 and BmVta1 during silkworm development and in different silkworm tissues and organs. The results showed that they were significantly up-regulated in metamorphosis, adulthood and embryogenesis relative to larval stages, and displayed a roughly similar tissue-and-organ specificity for transcriptions in silkworm larvae. Importantly, BmVps4 was down-regulated during the early period of the fifth instar, reaching the lowest level of transcription on Day 6, then up-regulated from Day 7 to the wandering, spinning and pupal stages, and down-regulated again in adulthood. Moreover, knocking down BmVps4 by RNA interference significantly inhibited silk gland growth, shortened spinning time, prolonged pupation, reduced pupal size and weight, and increased moth wing defects. Together, our data demonstrate the critical and broad requirements for BmVps4 in silkworm metamorphosis.

Cloning and function analysis of elongase of very long chain fatty acid gene Bmelo424 in silkworm

Genes belonging to the elongases of very long chain fatty acid (ELOVL) family affect many physiological functions in organism. In this paper, Bmelo424 gene, a member of the ELOVL family in silkworm, was cloned and its ORF was 558 bp. Its protein sequence was predicted to have four transmembrane domains, six serine phosphorylation sites, eight threonine phosphorylation sites and four tyrosine phosphorylation sites, and its subcellular localization was in the endoplasmic reticulum. Secondary structure analysis showed that the percentage of alpha-helix and beta-strand was 26.7% and 20% respectively. The results of fluorescence quantitative PCR showed that Bmelo424 gene was expressed in all tissues of silkworm, especially with the highest expression in head. By heterologous expression of Bmelo424 gene in Saccharomyces cerevisiae, the effect of Bmelo424 gene on fatty acid elongation was studied. GC-MS results indicated that the fatty acid content of C16:1n-7 in S. cerevisiae with pYES2-Bmelo424 recombinant plasmid increased significantly, whereas the content of C16:0, C18:0 and C18:1n-9 decreased. The results of temperature stress revealed that Bmelo424 gene could improve the low temperature adaptability of S. cerevisiae, but its high temperature adaptability decreased. This provides a reference for exploring the function of Bmelo424 gene in silkworm.

The fungal-resistance factors BmSPI38 and BmSPI39 predominantly exist as tetramers, not monomers, in Bombyx mori.

Previous studies have indicated that trypsin inhibitor-like cysteine-rich domain (TIL)-type protease inhibitors, BmSPI38 and BmSPI39, suppress conidial germination and integument penetration of entomopathogenic fungi by inhibiting their cuticle-degrading proteases and might functions as fungal-resistance factors in the silkworm. To date, the physiological forms and functional significance of multimerization of BmSPI38 and BmSPI39 remain unknown. In this study, we investigated the physiological forms of BmSPI38 and BmSPI39 in Bombyx mori silkworms using multiple complementary methods, including activity staining, reducing and nonreducing sodium dodecyl sulfate polyacrylamide gel electrophoresis, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, western blotting and immunofluorescence. We found that recombinant BmSPI38 and BmSPI39 tend to form homologous multimers, and their dimers, trimers and tetramers possessed intense inhibitory activity against subtilisinA from Bacillus licheniformis. In contrast, their monomers showed no detectable inhibitory activity. Both BmSPI38 and BmSPI39 also exist mainly as stable tetramers in silkworm tissues, and they also predominantly function as a tetramer in these tissues. This study is the first to demonstrate this preferred quaternary form of a TIL-type protease inhibitor and will likely help to elucidate the mechanisms of BmSPI38 and BmSPI39 in the innate immune response of the silkworm.

Host plant-derived allelochemicals and metal components are associated with oxidative predominance and antioxidant plasticity in the larval tissues of silkworm, Antheraea mylitta: Further evidence of joint effects hypothesis.

Tasar silkworm, Antheraea mylitta is a polyphagous insect that primarily feeds on Terminalia arjuna, Terminalia tomentosa and Shorea robusta. However, larval rearing on S. robusta results in poor performance for the reasons unexplored. Oxidative burden imposed by host plants is presumed to be a determining factor for larval fitness. With this hypothesis we have analyzed the foliar constituents of the respective host plants, the levels of oxidative stress and antioxidant protection in the larval tissues in response to their altered feeding on different host plants for different durations (2 and 10 days). Results indicate that S. robusta leaves contain the highest amount of tannin and redox active metals compared to those of other host plants. Consequently, hemolymph and midgut tissues of the larvae shifted to S. robusta exhibited oxidative predominance. Increased activities of superoxide dismutase, catalase and glutathione S-transferase in the larval tissues indicated an adaptive response to host plant driven oxidative assault. Our in vitro study also strongly supplements the in vivo findings indicating S. robusta foliages as a strong inducer of lipid peroxidation (LPx). Copper and Iron were found to be more potent in inducing LPx in the midgut tissues of the larvae compared to Zinc and Manganese. This study for the first time demonstrates the combined implications of host plant derived allelochemicals and elements on oxidative stress and antioxidant plasticity in this insect. The overall findings also brace up the newly emerging concept on joint effects hypothesis (organic and elemental defence) for enhanced plant defence.

Molecular cloning and characterization of C1 tetrahydrofolate (C1-THF) synthase in Bombyx mori, silkworm

Folate metabolism pathway is mainly associated with syntheses of nucleic acids and proteins as well as DNA methylation and repair. Cytoplasmic C1 tetrahydrofolate (C1-THF) synthase is a central enzyme in folate metabolism and plays an important role in C1-THF conversion. The full-length sequence of silkworm (Bombyx mori) cytoplasmic C1-THF synthase (BmC1-THF synthase) gene including an open reading frame (ORF) of 932 amino acid residues was cloned. Phylogenetic analysis indicated that BmC1-THF synthase shares 84% and 81% identity with C1-THF synthase of Papilio Xuthus and Danaus plexippus, respectively. Conserved sequence analysis showed that the 330 to 710 amino acid residues of BmC1-THF synthase were highly conserved among various organisms. Recombinant BmC1-THF synthase protein with a molecular weight of about 105.5 kDa was expressed in E. coli cells and identified using SDS-PAGE and western blot analysis. The expression of BmC1-THF synthase gene in eight silkworm tissues revealed that BmC1-THF synthase gene is widely expressed in various tissues of silkworm and highly expressed in the fat body. The expression characteristics of BmC1-THF synthase gene in response to oxidative stress were conducted under phoxim and high temperature (30 °C) exposure. The results showed that the transcriptional level of BmC1-THF synthase gene was upregulated by 3.435-fold and 6.845-fold after phoxim and high temperature (30 °C) exposure, respectively, indicating that BmC1-THF synthase gene may play a significant role in response of silkworm to oxidative stresses.

DNA methylation in silkworm genome may provide insights into epigenetic regulation of response to Bombyx mori cypovirus infection

DNA methylation is an important epigenetic modification that regulates a wide range of biological processes including immune response. However, information on the epigenetics-mediated immune mechanisms in insects is limited. Therefore, in this study, we examined transcriptomes and DNA methylomes in the fat body and midgut tissues of silkworm, Bombyx mori with or without B. mori cytoplasmic polyhedrosis virus (BmCPV) infection. The transcriptional profile and the genomic DNA methylation patterns in the midgut and fat body were tissue-specific and dynamically altered after BmCPV challenge. KEGG pathway analysis revealed that differentially methylated genes (DMGs) could be involved in pathways of RNA transport, RNA degradation, nucleotide excision repair, DNA replication, etc. 27 genes were shown to have both differential expression and differential methylation in the midgut and fat body of infected larvae, respectively, indicating that the BmCPV infection-induced expression changes of these genes could be mediated by variations in DNA methylation. BS-PCR validated the hypomethylation of G2/M phase-specific E3 ubiquitin-protein ligase-like gene in the BmCPV infected midgut. These results demonstrated that epigenetic regulation may play roles in host-virus interaction in silkworm and would be potential value for further studies on mechanism of BmCPV epithelial-specific infection and epigenetic regulation in the silkworm.

Characterization of an inhibitor of apoptosis gene (BmSurvivin-2) from the silkworm, Bombyx mori

The inhibitor of apoptosis proteins (IAP) plays an important role in maintaining the balance between cell proliferation and cell death. Here, we describe an IAP named BmSurvivin-2 isolated from tissues of Bombyx mori that contains only one baculoviral IAP repeat (BIR) domain and lacks a really interesting new gene (RING) finger domain. Cell viability and DNA fragment analysis showed that over-expression of BmSurvivin-2 could inhibit actinomycin D (ActD)-induced apoptosis in Sf9 cells, and its anti-apoptotic activity was dependent on its N-terminal BIR domain. Real-time PCR analyses indicated that BmSurvivin-2 mRNA was expressed in all tissues of silkworm and the highest expression level was found in testis and head. Expression of BmSurvivin-2 was found to gradually increase during the wandering stage of silkworm and decreased after wandering. Similar to deterin but not survivin, BmSurvivin-2 was primarily located in the cytoplasm. All these results provide insight into the role of a novel IAP in the silkworm, B. mori.

Changes in the total protein, carbohydtate and lipid contents in selected tissues of silkworm, Bombyx mori L. under the influence of a juvenoid R394

A juvenoid. R394 (Ethyl 9-cyclohexyl-3,7-dimethyl-2,4-nonadienoate) was applied topically to 5th instar silkworm, Bombyx mori L. larvae (Hybrid: KA x NB4D2) at a dose of 0.039 nl/larva at 24, 48, 72 and 96 h, for silk yield improvement. Three major selected tissues viz., posterior silk gland (PSG), haemolymph and fat body were collected from fully-grown larvae and the total protein, total carbohydrate and total lipid contents were estimated following standard procedures. The result indicated that the content of these primary metabolites varied significantly in the selected tissues depending on the time of juvenoid application. The highest protein content was observed in the haemolymph and silk gland in the larvae treated at 72 h whereas the fat body protein content was lowest for the same treatment. The total carbohydrate was recorded lowest in the 72 h treated larvae as against the highest in the control both in haemolymph and fat body with no significant change in PSG. The total lipid content did not show any notable variation in the concentration on juvenoid administration except in the silk gland treated up to 72 h which showed a decline. The results indicate that the juvenoid induces tissue-specific responses in terms of turnover in primary metabolites which commensurates with the corresponding changes observed in the cocoon weight and cocoon shell weight.

Identification and Characterization of BmVta1, a Bombyx mori (Lepidoptera: Bombycidae) Homologue for Vta1 That is Up-Regulated in Development.

Vps20-associated 1 (Vta1) positively regulates Vacuolar protein sorting 4 (Vps4) to disassemble endosomal sorting complex required for transport III (ESCRT-III) for repeated uses in multivesicular body (MVB) pathway, virus budding and other processes. Currently, these proteins have mainly been studied in yeast and mammalian cells, while identities of them in insects remain largely unknown. We previously identified BmVps4, a Vps4 homologue from Bombyx mori. Here, we report the identification of a homologue for Vta1, designated as BmVta1. The BmVta1 cDNA contains an open reading frame of 933 bp and encodes a protein of 311 amino acid residues. We cloned BmVta1, expressed it in Escherichia coli, and prepared mouse polyclonal antibodies. Like BmVps4, BmVta1 is well conserved as shown by sequence analysis. Both proteins are localized in cytoplasm as revealed by subcellular location analysis. Interestingly, as revealed by semi-quantitative reverse transcription polymerase chain reaction (sqRT-PCR), transcriptions of BmVta1 and BmVps4 are highly up-regulated during silkworm metamorphosis and embryogenesis but down-regulated during larva stages, and are of higher levels in head, silk gland and testis than in Malpighian tube, fat body and ganglion, indicating important and similar roles of them in silkworm development and in silkworm tissues and organs. However, compared to BmVps4, the transcription of BmVta1 changes less drastically during development and is of much higher levels in midgut, ovary and hemolymph, suggesting the existence of distinct requirements of them in silkworm development and in certain tissues and organs.

Determination of Metal Contents in the Tissues of Silkworm after Fed with Nanoparticles Using Inductively Coupled Plasma-Mass Spectrometry

Determination of Metal Contents in the Tissues of Silkworm after Fed with Nanoparticles Using Inductively Coupled Plasma-Mass Spectrometry