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Juvenile hormone restores larval pattern of sericin gene transcripts
Author(s) -
Yang Changsong,
Sehnal František,
Scheller Klaus
Publication year - 1996
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/(sici)1520-6327(1996)32:3/4<353::aid-arch8>3.0.co;2-t
Subject(s) - biology , moulting , instar , ecdysteroid , juvenile hormone , hemolymph , manduca sexta , larva , gene expression , gene , microbiology and biotechnology , galleria mellonella , metamorphosis , medicine , endocrinology , genetics , biochemistry , botany , virulence
The transcripts of sericin‐type genes MG1 and MG2 accumulate in Galleria mellonella silk glands during feeding and decline during molting. Three MG1 (1.9, 3.2, and 4.2 kb) and two MG2 (dominant 3.4 kb and minor 5.2 kb) transcripts are detectable from the penultimate instar until the end of cocoon spinning. Experiments with isolated larval abdomens showed that the dramatic change in the ratio of 1.9 and 4.2 kb MG1 transcripts in the last larval instar is due to lack of JH. Transient rise of ecdysteroid titre in the wandering larvae (day 5 of the last instar) is associated with appearance of additional MG1 transcripts (10.0, 7.2, and 5.0 kb), while the molt‐inducing ecdysteroid surge on day 7 causes a drop of all transcripts. The drop is prevented and the profile of transcripts is reverted to a larval‐like pattern when the last instar larvae are treated with a juvenoid. The profile of MG1 transcripts is affected only when the treatment is applied prior to the start of cocoon spinning (day 6), whereas the decline of the 3.4 kb MG2 transcript is averted with applications up to day 7. Presented results are interpreted as showing that JH causes a “status quo” effect by preventing the disappearance of certain transcripts during molting, exerts a “juvenilizing” effect by restoring the larval pattern of splicing, and affects developmental “programming,” presumably by affecting the future pattern of gene expression. © 1996 Wiley‐Liss, Inc.