DEVELOPMENTAL REGULATION OF GRANULE SIZE AND NUMBERS IN LARVAL SALIVARY GLANDS OF DROSOPHILA BY STEROID HORMONE ECDYSONE

Authors

  • Robert Farkaš,

    Corresponding author
    1. Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlárska 3, 833 06, Bratislava
      To whom correspondence should be addressed: Robert Farkaš, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlárska 3, 833 06 Bratislava, Slovakia. E-mail:ueenfark@savba.savba.sk
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  • Gabriela Šuáková

    1. Institute of Experimental Phytopathology and Entomology, Slovak Academy of Sciences, Nádražná 52, 900 28, Ivanka pri Dunaji, Slovakia
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To whom correspondence should be addressed: Robert Farkaš, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlárska 3, 833 06 Bratislava, Slovakia. E-mail:ueenfark@savba.savba.sk

Abstract

The size and number of secretory granules in late larval salivary glands of Drosophila melanogaster have been related to interecdysial and early metamorphic development represented by well-known puffs in polytene chromosomes. Interecdysial period (puff stage 1 (PS1)) is characterized by presence of numerous small granules (11,000 per cell). The transition from PSI to early metamorphic phase (PS2 and upwards), induced by rapid elevation in endogenous steroid hormone ecdysone, is accompanied by continuous growth of granule diameter with concomitant reduction in their number per cell. In the PS4, just prior to secretion, ∼3000 mature granules occur per cell. The mature state is associated with the change from hyperbolic to Gaussian distribution of granule number over their size range. Similar changes in secretory granule parameters were observed in interecdysial salivary glands explanted from 3rd instar larvae and cultured in vitro in medium containing 5×10−6m ecdysone.

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