To investigate the structure of silk and its degradation properties, we have monitored the structure of silk using scanning electron microscopy and frozen sections. Raw silk and degummed raw silk were immersed in four types of degradation solutions for 156 d to observe their degradation properties. The subcutaneous implants in rats were removed after 7, 14, 56, 84, 129, and 145 d for frozen sectioning and subsequent staining with hematoxylin and eosin (H.E.), DAPI, Beta-actin and Collagen I immunofluorescence staining. The in vitro weight loss ratio of raw silk and degummed raw silk in water, PBS, DMEM and DMEM containing 10% FBS (F-DMEM) were, respectively, 14%/11%, 12.5%/12.9%, 11.1%/14.3%, 8.8%/11.6%. Silk began to degrade after 7 d subcutaneous implantation and after 145 d non-degraded silk was still observed. These findings suggest the immunogenicity of fibroin and sericin had no essential difference. In the process of in vitro degradation of silk, the role of the enzyme is not significant. The in vivo degradation of silk is related to phagocytotic activity and fibroblasts may be involved in this process to secrete collagen. This study also shows the developing process of cocoons and raw silk.
The body often appears unwell after habitual dietary changes. The domestic silkworm (
Bombyx mori
) raised on artificial diets is a good model to explore the relationship between dietary changes and the balance of intestinal microbes.
This study assessed the effect of processing including boiling, roasting and fermenting on bioaccessibility of carotenoids (lutein, zeaxanthin, β-cryptoxanthin, α-carotene and β-carotene) from orange maize. Bioaccessibility of carotenoids was analysed using a three-stage in vitro digestion. High-performance liquid chromatography was used to analyse the contents of carotenoid compounds in the processed orange maize products and digesta. On average, boiled maize had the highest retention rate (79.0%) of carotenoids followed by fermented porridge (73.8%), fermented maize (68.4%) and unfermented porridge (59.0%). Roasted maize had the lowest retention rate of 56.1%. Without further processing, carotenoids recovery from raw orange maize ranged from 73.0% to 100.5%. After treatments, carotenoids recovery showed varying levels of increase except for fermented maize. The average recovery of carotenoids in whole digesta of boiled maize, roasted maize, fermented porridge and unfermented porridge was 108.5%, 116.9%, 101.9% and 110.7%, respectively.
The high adaptability of insects to food sources has contributed to their ranking among the most abundant and diverse species on Earth. However, the molecular mechanisms underlying the rapid adaptation of insects to different foods remain unclear. We explored the changes in gene expression and metabolic composition of the Malpighian tubules as an important metabolic excretion and detoxification organ in silkworms (Bombyx mori) fed mulberry leaf and artificial diets. A total of 2436 differentially expressed genes (DEGs) and 245 differential metabolites were identified between groups, with the majority of DEGs associated with metabolic detoxification, transmembrane transport, and mitochondrial function. Detoxification enzymes, such as cytochrome P450 (CYP), glutathione-S-transferase (GST), and UDP-glycosyltransferase, and ABC and SLC transporters of endogenous and exogenous solutes were more abundant in the artificial diet group. Enzyme activity assays confirmed increased CYP and GST activity in the Malpighian tubules of the artificial diet-fed group. Metabolome analysis showed increased contents of secondary metabolites, terpenoids, flavonoids, alkaloids, organic acids, lipids, and food additives in the artificial diet group. Our findings highlight the important role of the Malpighian tubules in adaptation to different foods and provide guidance for further optimization of artificial diets to improve silkworm breeding.
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