Effects of Hormone Agonists on Sf9 Cells, Proliferation and Cell Cycle Arrest

Methoxyfenozide and methoprene are two insecticides that mimic the action of the main hormones involved in the control of insect growth and development, 20-hydroxyecdysone and juvenile hormone. We investigated their effect on the Spodoptera frugiperda Sf9 cell line. Methoxyfenozide was more toxic than methoprene in cell viability tests and more potent in the inhibition of cellular proliferation. Cell growth arrest occurred in the G2/M phase after a methoprene treatment and more modestly in G1 after methoxyfenozide treatment. Microarray experiments and real-time quantitative PCR to follow the expression of nuclear receptors ultraspiracle and ecdysone receptor were performed to understand the molecular action of these hormone agonists. Twenty-six genes were differentially expressed after methoxyfenozide treatment and 55 genes after methoprene treatment with no gene in common between the two treatments. Our results suggest two different signalling pathways in Sf9 cells

Ripening and dehiscence of the anther in some Crocus(Iridaceae) species

Abstract The anther development was examined in some Crocus species, by light and scanning electron microscopy. Epidermal cells develop a longitudinal stomium which is connected to the interlocular septum by cells with wide intercellular spaces.Endothecial cells are mono or bilayered, and they develop annular wall thickenings.Middle layer cells degenerate shortly after the microspore release. Tapetal cells are secretory with orbicules, and they form the tapetal membrane. The stomium disjoins from the interlocular septum after the lysis of the middle lamellae in the abscission region. The stomial cells break long before the flower opening, and in C. boryithey show signs of programmed cell death. Following the flower opening, the locular walls shrink tangentially, with flattening of epidermal cells and shortening of endothecial cells, and they bend up to turn inside out, exposing the pollen grains. The results are discussed in relation to the dehiscence mechanism