No abstract

The patterns of puffing activity in the salivary gland polytene chromosomes have been studied during the late larval and prepupal stages of the medfly Ceratitis capitata. A total of 128 loci, with significant changes in puffing activity during this developmental period, were assigned to the five autosomes of the medfly. Two waves of puffing activity were observed, the first during the late larval stage and the second during the prepupal development. Overall puffing activity can be divided into four groups, group-IV activity being most conspicuous with 58 active loci. The major changes in puffing activity take place around jumping, a characteristic event occurring about 6 h before puparium formation, at puparium formation, and during midprepupal development. The overall puffing activity shows a positive correlation to the ecdysone titer in the hemolymph, suggesting that most of the changes in the activity of the puffs during the late larval and prepupal stages of the medfly may be regulated by ecdysone.Résumé : La nodulation des chromosomes polytènes de la glande salivaire a été étudiée au cours du développement de la larve et de la prépupe chez la mouche méditerranéenne Ceratitis capitata. Un total de 128 loci montrant des changements significatifs au niveau de la nodulation lors de cette période du développement ont été assignés aux cinq autosomes de la mouche méditerranéenne. Deux épisodes de nodulation ont été observés, le premier survenant au stade larvaire tardif et le second se produisant durant le développement de la prépupe. Globalement, on peut reconnaître quatre groupes de loci en fonction de leur nodulation, le groupe quatre étant le plus important avec 58 loci actifs. Les principaux changements surviennent autour du « jumping », un événement caractéristique qui s'observe environ 6 h avant la formation du puparium, lors de la formation du puparium ainsi qu'à mi-chemin du développement de la prépupe. Globalement, la nodulation est corrélée positivement avec le titre d'ecdysone dans l'hémolymphe, ce qui suggère que la plupart des changements observés au niveau de la nodulation durant ces stades de développement chez la mouche méditerranéenne pourraient être régulés par l'ecdysone.

No abstract

The promoter of the hsp70 gene of Drosophila melanogaster has been widely used for the expression of foreign genes in other insects. It has been generally assumed that because this gene is highly conserved, its promoter will function efficiently in other species. We report the results of a quantitative comparison of the activities of the medfly and D. melanogaster hsp70 promoters in vivo in transformed medflies. We constructed transformed lines containing the lacZ reporter gene under the control of the two promoters by using Minos-mediated germ-line transformation. The activity of each promoter was evaluated in 15 transformed lines by beta-galactosidase quantitative assays. The heat-inducible activity of the medfly promoter was found several times higher than the respective activity of the heterologous D. melanogaster promoter. These results were confirmed by northern blot analysis and indicate that the D. melanogaster promoter does not work efficiently in medfly. The -263/+105 medfly promoter region that was used in this study was found able to drive heat shock expression of the lacZ reporter gene in all stages of medfly, except early embryonic stages, in a similar fashion to the endogenous hsp70 genes. However the heat inducible RNA levels driven from this promoter region were significantly lower than the endogenous hsp70 RNA levels, suggesting that additional upstream and/or downstream sequences to the -263/+105 region may be necessary for optimum function of the medfly hsp70 promoter in vivo.

No abstract