RRC ID 22821
Author Matsui H, Kakei M, Iwami M, Sakurai S.
Title Hormonal regulation of the death commitment in programmed cell death of the silkworm anterior silk glands.
Journal J Insect Physiol
Abstract During larval-pupal transformation, the anterior silk glands (ASGs) of the silkworm Bombyx mori undergo programmed cell death (PCD) triggered by 20-hydroxyecdysone (20E). Under standard in vitro culture conditions (0.3 ml of medium with 1 μM 20E), ASGs of the fourth-instar larvae do not undergo PCD in response to 20E. Similarly, larvae of the fifth instar do not respond to 20E through day 5 of the instar (V5). However, ASGs of V6 die when challenged by 20E, indicating that the glands might be destined to die before V6 but that a death commitment is not yet present. When we increased the volume of culture medium for one gland from 0.3 to 9 ml, V5 ASGs underwent PCD. We examined the response of ASGs to 20E every day by culturing them in 9 ml of medium and found that ASGs on and after V2 were fully responsive to 20E. Because pupal commitment is associated with juvenile hormone (JH), the corpora allata (a JH secretory organ) were removed on day 3 of the fourth larval instar (IV3), and their ASGs on V0 were cultured with 20E. Removal of the corpora allata allowed the V0 larval ASGs to respond to 20E with PCD. In contrast, topical application of a JH analogue inhibited the response to 20E when applied on or before V5. We conclude that the acquisition of responsiveness to 20E precedes the loss of JH sensitivity, and that the death commitment in ASGs occurs between V5 and 6.
Volume 58(12)
Pages 1575-81
Published 2012-12-1
DOI 10.1016/j.jinsphys.2012.09.012
PII S0022-1910(12)00239-9
PMID 23063728
MeSH Animals Bombyx / growth & development* Cell Death Ecdysone / analogs & derivatives* Ecdysone / physiology Exocrine Glands / physiology Glucose Oxidase / metabolism Juvenile Hormones / physiology* Kruppel-Like Transcription Factors / metabolism Metamorphosis, Biological* Silk
IF 2.246
Times Cited 12