Action of 24-epibrassinolide on a cell line of the beet armyworm,Spodoptera exigua

Abstract

The Spodoptera exigua cell line Se4 is sensitive for ecdysteroid activity stimulated by the insect molting hormone, 20-hydroxyecdysone (20E), showing a cease in cell proliferation (with 50% inhibition around 1 microM) and characteristic cell morphology changes with aggregation and formation of long filamentous cytoplasmic extensions. The bisacylhydrazine tebufenozide also triggered such typical cellular effects in Se4, and in addition, it showed an affinity for binding in competition with 3H-ponasterone A (PoA) that was similar to 20E (with 50% competition around 1 microM), confirming that such non-ecdysteroids display an ecdysteroid agonist activity. In contrast, when Se4 cells were incubated with the native plant hormone 24-epibrassinolide (24BR), none of the effects triggered by 20E were observed. Hence, a competition binding experiment with 3H-PoA demonstrated no affinity of 24BR for binding to the ecdysteroid receptor in the Se4 cell line. In another series of experiments, the Se4 cell line was tested in sensitivity response to increased acetylcholinesterase (AchE) activity after treatment with ecdysteroid active compounds. The AchE activity measured in the cell line is discussed in relation to inhibition by eserine. The obtained results suggest that 24BR exerted no ecdysteroid activity.

Steroid plant hormones: Effects outside plant kingdom

“…The first experiments showed that steroidal phytohormones could affect normal growth and development of insects. A number of BS effects were revealed at different levels [22], including intact animals [15,23,24], isolated tissues [23,25,26], cultured cells [27,28], particular insect neurons [29], and protein molecules (ecdysteroid receptors) [23,28,30,31]. However, the results of these experiments are not always consistent with each other.…”

“…However, the affinity in most experiments was 10-to 1000 fold lower than that observed for binding to radiolabeled ponasterone A, and no competition at all was observed for EcR in intact Se4 cells even at relatively high (100 lM) concentration of EBl [28]. A number of synthetic hybrids of BS and ecdysteroids were prepared and assessed for their activities in the Drosophila melanogaster B II cell bioassay [33].…”

Insecticidal properties of Sclerotinia sclerotiorum agglutinin and its interaction with insect tissues and cells

“…After incubation, the cell numbers were counted using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) (SigmaeAldrich) as a substrate according to Decombel et al (2005). The MTT assay is based on the enzymatic conversion of a yellow tetrazolium salt to an insoluble formazan product by the mitochondria of viable cells.…”

Selection for resistance to methoxyfenozide and 20‐hydroxyecdysone in cells of the beet armyworm, Spodoptera exigua

“…The Se4 cell line is sensitive for ecdysteroid activity stimulated by 20E and tebufenozide (Decombel et al, 2005) and can be used as a model to study the mode of action of ecdysteroids and their agonists. First, we investigated the relative potency of the four ecdysteroid agonists on cell proliferation in comparison with 20E.…”

“…After incubation, the cell numbers were counted with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) technique according to Decombel et al (2005). Briefly, 100 µl of cell solution was transferred to a microtube (Eppendorf) and 100 µl of 1 mg/ml MTT solution was added.…”