Physiological requirements for 20-hydroxyecdysone-induced rectal sac distention in the pupa of the silkworm, Bombyx mori.
نویسندگان
چکیده
Successful insect development is achieved via appropriate fluctuation of ecdysteroid levels. When an insect's ecdysteroid level is disrupted, physiological and developmental defects occur. In the pupa of the silkworm, Bombyx mori, the rectal sac is an essential organ that operates as a repository for degraded ecdysteroids, and it can be distended by administration of 20-hydroxyecdysone (20E). Our previous study showed that rectal sac distention appears 4 days after 20E administration. Hemolymph ecdysteroid levels, however, decrease to lower level during this period. Thus, the timing of the rectal sac distention does not match with that of ecdysteroid elevation. Here, we examine how 20E induces rectal sac distention. A ligature experiment and ecdysteroid quantification showed that continuous 20E stimulation induces rectal sac distention. Thorax tissue contributed to the continuous 20E stimulation needed to induce distention. Ecdysteroid released from the thorax tissue may be converted to 20E by ecdysone 20-hydroxylase to produce continuous 20E stimulation. Thus, the ecdysone metabolic pathway plays a critical role in rectal sac distention.
منابع مشابه
Rectal sac distention is induced by 20-hydroxyecdysone in the pupa of Bombyx mori.
Holometabolous insects do not excrete but store metabolic wastes during the pupal period. The waste is called meconium and is purged after adult emergence. Although the contents of meconium are well-studied, the developmental and physiological regulation of meconium accumulation is poorly understood. In Bombyx mori, meconium is accumulated in the rectal sac; thereby, the rectal sac distends at ...
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ورودعنوان ژورنال:
- Journal of insect physiology
دوره 56 6 شماره
صفحات -
تاریخ انتشار 2010