Space flight experiment on Chinese silkworm on board the Russian 10th Biosatellite

The Evaluation of the Biological Effects of Melanin by Using Silkworm as a Model Animal

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.

Subchronic toxicity of magnesium oxide nanoparticles to Bombyx mori silkworm

Despite many research efforts devoted to the study of the effects of magnesium oxide nanoparticles (MgO NPs) on cells or animals in recent years, data related to the potential long-term effects of this nanomaterial are still scarce. The aim of this study is to explore the subchronic effects of MgO NPs on Bombyx mori silkworm, a complete metamorphosis insect with four development stages (egg, larva, pupa, month). With this end in view, silkworm larvae were exposed to MgO NPs at different mass concentrations (1%, 2%, 3% and 4%) throughout their fifth instar larva. Their development, survival rate, cell morphology, gene expressions, and especially silk properties were compared with a control. The results demonstrate that MgO NPs have no significant negative impact on the growth or tissues. The cocooning rate and silk quality also display normal results. However, a total of 806 genes are differentially expressed in the silk gland (a vital organ for producing silk). GO (Gene Ontology) results show that the expression of many genes related to transporter activity are significantly changed, revealing that active transport is the main mechanism for the penetration of MgO NPs, which also proves that MgO NPs are adsorbed by cells. KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis demonstrates that the longevity regulating pathway-worm, peroxisome and MAPK signaling pathway are closely involved in the biological effects of MgO NPs. Overall, subchronic exposure to MgO NPs induced no apparent negative impact on silkworm growth or silks but changed the expressions of some genes.

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.