Hormonal regulation and developmental role of Krüppel homolog 1, a repressor of metamorphosis, in the silkworm Bombyx mori

Feb 11, 2014Developmental biology

Hormone control and development role of Krüppel homolog 1, a metamorphosis blocker, in the silkworm Bombyx mori

AI simplified

CRISPR Gene Editing on OpenScience ↗PubMed ↗DOI ↗

Abstract

The expression of Krüppel homolog 1 (Kr-h1) in the epidermis of silkworm larvae is induced by juvenile hormone (JH) secreted by the corpora allata.

Kr-h1 mediates the antimetamorphic effect of JH during larval development.
A transient induction of Kr-h1 occurs at the prepupal stage, likely influenced by JH from sources other than the corpora allata and the surge of ecdysteroid.
Transgenic silkworms overexpressing Kr-h1 experienced growth until the spinning stage, but their development was arrested at the prepupal stage.
Removal of the corpora allata in transgenic silkworms led to prepupal arrest without precocious pupation or larval-larval molt.
Kr-h1 is involved in repressing metamorphosis, but it does not independently facilitate normal larval molt.

AI simplified

Juvenile hormone (JH) has an ability to repress the precocious metamorphosis of insects during their larval development. Krüppel homolog 1 (Kr-h1) is an early JH-inducible gene that mediates this action of JH; however, the fine hormonal regulation of Kr-h1 and the molecular mechanism underlying its antimetamorphic effect are little understood. In this study, we attempted to elucidate the hormonal regulation and developmental role of Kr-h1. We found that the expression of Kr-h1 in the epidermis of penultimate-instar larvae of the silkworm Bombyx mori was induced by JH secreted by the corpora allata (CA), whereas the CA were not involved in the transient induction of Kr-h1 at the prepupal stage. Tissue culture experiments suggested that the transient peak of Kr-h1 at the prepupal stage is likely to be induced cooperatively by JH derived from gland(s) other than the CA and the prepupal surge of ecdysteroid, although involvement of unknown factor(s) could not be ruled out. To elucidate the developmental role of Kr-h1, we generated transgenic silkworms overexpressing Kr-h1. The transgenic silkworms grew normally until the spinning stage, but their development was arrested at the prepupal stage. The transgenic silkworms from which the CA were removed in the penultimate instar did not undergo precocious pupation or larval-larval molt but fell into prepupal arrest. This result demonstrated that Kr-h1 is indeed involved in the repression of metamorphosis but that Kr-h1 alone is incapable of implementing normal larval molt. Moreover, the expression profiles and hormonal responses of early ecdysone-inducible genes (E74, E75, and Broad) in transgenic silkworms suggested that Kr-h1 is not involved in the JH-dependent modulation of these genes, which is associated with the control of metamorphosis.

Full Text

Full text is available at the source.

View full text (XML) ↗View full text ↗

Hormonal regulation and developmental role of Krüppel homolog 1, a repressor of metamorphosis, in the silkworm Bombyx mori

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the crispr gene editing brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the crispr gene editing brief