Development of Drosophila imaginal discs in vitro: Effects of ecdysone concentration and insulin

Abstract

A detailed scoring system was used to determine the effects of a variety of factors on the evagination and differentiation of Drosophila imaginal discs cultured in vitro. In modified Schneider's Drosophila medium, P-ecdysone induced development a t concentrations approximately 1 0 0~ lower than aecdysone. The metamorphosis of imaginal discs consists of two processes, evagination and differentiation, which were found to be differentially sensitive to hormone concentration. Optimal differentiation occurred at relatively low P-ecdysone concentrations (30 ngiml), while complete evagination required higher levels (500 ng/ml). Even at the optimal hormone concentration for differentiation, not all discs differentiated completely, and each region of the eye, antenna, wing, and leg exhibited a characteristic frequency of differentiation. In addition, a strong negative correlation between the extent of evagination and the quality of differentiation was observed. Bovine insulin stimulated P-ecdysone induced evagination, but at the same time it inhibited differentiation.The imaginal discs of Drosophila melanogaster can be maintained in vitro, and, if the culture medium is supplemented with a molting hormone, will undergo metamorphic development and differentiate the complete range of adult cuticular structures. This culture system promises to be a useful tool in the investigation of developmental processes of imaginal discs.

Expression of the gene encoding an insulin‐related peptide inLocusta (Insecta, Orthoptera)

“…Considering the presence of apparent low levels of T2 transcripts in all tissues investigated, we hypothesize that they are related to the existence of an autocrine/paracrine control of cell growth and division, a function which is generally observed with insulin molecules, at least in vitro (Seecof and Dewhurst, 1974;Martin and Shearn, 1980;Barrett and Loughton, 1987;Vanhems et al, 1990). A comparison of the intensities of the bands obtained after primer-extension experiments on LIRP brain RNA suggests that T1 transcripts are 10-50-times more abundant than T2 transcripts.…”

Effect of bombyxin-II, an insulin-related peptide of insects, on Bombyx mori hemocyte division in single-cell culture

“…The growth-promoting activity of insulin and insulin-like growth factors has been amply documented in both vertebrate cells and organ cultures. In insect cell cultures, exogenous insulin and insulin-like growth factors provoke physiological effects (Seecof and Dewhurst, 1974;Davis and Shearn, 1977;Martin and Shearn, 1980;Mosna, 1981;Wyss, 1982;Cullen and Milner, 1991;Hatt et al, 1994Hatt et al, , 1997 and mammalian insulin is presently a routine additive to Drosophila culture media (Wyss, 1988;Echalier, 1997). Nijhout and Grunert (2002) reported that bombyxin-II stimulates cell division and growth of wing imaginal disks of Precis coenia.…”

Isolation and structural characterization of an insulin‐related molecule, a predominant neuropeptide from Locusta migratoria

“…They indicate that locusla corporu cnrcliuca contain remarkably large amounts of one single insulin form, in contrast to multiple insulin isoforms of Bornby.\-nzori, the only other insect species from which insulin-related peptides have been isolated and characterized [Nagasawa, H., Kataoka, H., Isogai, A., Tamura, S., Suzuki, A., Mizoguchi, A., Fujiwara, Y., Suzuki The presence in insects of molecules structurally related to mammalian insulin has been inferred for more than 20 years on the basis of two types of results: (A) antibodies directed against mammalian insulins reacted positively with antigenic determinants present in the brain and other tissues of several insect species [ 11; (B) injections ofmammalian insulins affected blood sugar and lipid levels [I -51. In addition, mamnalian insulin also stimulates growth and differentiation in cell c dtures [6,71 and cultures of imaginal disks [8]. The efforts aimed at the isolation and full structural characterization of insect insulin-related molecules were unsuccessful until the unexpected finding of a prothoracicotropic factor from B. rizori with structural homologies to mammalian insulins [9 -1 I].…”