Establishment of a gnotobiotic silkworm model

Abstract

Gnotobiotic animals are useful for investigation of the effects of specific lactic acid bacteria on individual animals. Here we report that lactic acid bacteria colonize and proliferate in the intestinal tract of germ-free silkworms. When silkworms hatching from formalin-treated eggs were reared to fifth-instar larvae with an artificial diet containing antibiotics, bacteria and fungi were not observed in their intestines. An antibiotic-free diet supplemented with viable lactic acid bacteria, such as Enterococcus faecalis 0831-07, Lactococcus lactis 11/19-B1, or Leuconostoc carnosum #7-2, was fed to the germ-free silkworms for 1 day. After feeding the larvae on a diet without lactic acid bacteria for 5 days, each type of lactic acid bacterium was found in the intestine. Moreover, an increase in the number of Enterococcus faecalis 0831-07 was observed in the intestine 2-5 days after ingestion. These findings suggest that we successfully established a method to construct a gnotobiotic silkworm model.

The Response of the Estrogen-Related Receptor to 20-Hydroxyecdysone in Bombyx mori: Insight Into the Function of Estrogen-Related Receptor in Insect 20-Hydroxyecdysone Signaling Pathway

“…Since the completion of the genome sequence, the silkworm ( Bombyx mori ) has become a widely used model insect for lepidopteran research, and a general model organism for life sciences, toxicology, and fungal infections ( International Silkworm Genome, 2008 ; Suetsugu et al, 2013 ; Meng et al, 2017 ; Abdelli et al, 2018 ; Nakajima et al, 2018 ; Matsumoto and Sekimizu, 2019 ). In previous research, we have demonstrated that the Bombyx mori ERR (BmERR) is involved in the growth and development of silkworm embryos and larvae by regulating the expression of glucose metabolism-related genes ( Long et al, 2020 ; Shen et al, 2021 ).…”