Patterns of puffing activity in the salivary gland polytene chromosomes of the medflyCeratitis capitata, during larval and prepupal development

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.

cDNA cloning, characterization, and developmental expression of the 20S proteasome α5 subunit in the Mediterranean fruit fly Ceratitis capitata

“…This strain has been maintained in our laboratory for more than 25 years under standard conditions (25 ± 1°C, 40-50% relative humidity and 12 h light:12 h dark photoperiod) as previously described (Mintzas et al, 1983). Precise staging of the medfly cultures was obtained according to a procedure described previously (Gariou-Papalexiou et al, 1999). Following this procedure, the embryonic, larval, and prepupal stages last 49 ± 1, 150 ± 2, and 40 ± 2 h, respectively, while the pupal stage lasts about 8 days.…”

“…The numbers indicate the age of each developmental stage in hours. J represents the stage during which the larvae jump off the food and occurs 6 h before white puparium formation (WP) (Gariou-Papalexiou et al, 1999). Ethidium bromide staining of rRNA is showing under the Northern blots as a control for even RNA loading.…”

Cloning, characterization, and developmental expression of the ribosomal protein S21 gene of the Mediterranean fruit fly Ceratitis capitata

“…This strain has been maintained in our laboratory for more than 30 years under standard conditions (25 ± 1°C, 40-50% relative humidity and 12 h light:12 h dark photoperiod) as previously described (Mintzas et al, 1983). Precise staging of the medfly cultures was obtained according to a procedure described previously (Gariou-Papalexiou et al, 1999). Following this procedure, the embryonic, larval, and prepupal stages last 49 ± 1, 151 ± 2, and 40 h, respectively while the pupal stage lasts about 8 days.…”

Developmental profiles and ecdysone regulation of the mRNAs for two ecdysone receptor isoforms in the Mediterranean fruit flyCeratitis capitata

“…This higher dipteran species has a similar life cycle to D. melanogaster and presents several important advantages for studying 20E regulation. It has well characterized salivary gland polytene chromosomes (Zacharopoulou, 1990) and can be staged precisely during the last hours of larval development because of the jumping event, which takes place about 6 h before puparium formation and coincides with the onset of the first 20E induced puffing cycle (Gariou‐Papalexiou et al ., 1999). Furthermore, C. capitata is the best‐studied fruit fly species of economic importance at the genetic and molecular levels.…”

“…In previous studies we have determined the puffing patterns of 128 loci in the salivary gland polytene chromosomes during medfly metamorphosis and demonstrated that 20E regulates the activity of most of these puffs (Gariou‐Papalexiou et al ., 1999, 2001). We also have cloned and characterized a medfly ecdysone receptor (CcEcR), the homologue of the Drosophila EcR‐B1 isoform (Verras et al ., 1999).…”