Correlation among corpus allatum volume, cell size, and juvenile hormone biosynthesis in ovariectomized adult <i>Blattella germanica</i>

Schal

1996

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Juvenile hormone (JH) biosynthesis by corpora allata (CAI from embryos of the cockroach Diploptera punctata was measured at four stages during the latter half of embryogenesis. Individual glands from 32-day-old embryos that had completed 49% of embryonic development synthesized 0.3 pmol JH Ill h-'. By day 46 (70% development) gland activity rose to 1.1 pmol J H h-', but on subsequent days JH synthetic rates declined, measuring only 0.8 pmol h-' on day 56 (86% development) and 0.5 pmol h-' on day 60 (92% development). Differences in JH biosynthesis by CA from different-aged embryos were more evident when gland activity was corrected for either corpus allatum cell number, which increased progressively from fewer than 200 cells per gland on day 32 to almost 700 cells per gland on day 60, or embryo mass, which increased from 1.6 mg per embryo on day 32 to 10.8 mg per embryo on day 60. J H biosynthetic rates were significantly inhibited in a medium containing M Dip-allatostatin 7 which suppressed CA activity by 68, 83, 76, and 51°% o n days 32, 46, 56, and 60, respectively. In all embryonic stages JH production was significantly stimulated by incubation of glands with 200 pM farnesol, a late precursor in the J H biosynthetic pathway. D 1~9 6Wcy-Liss, Inc.

Section: Activity Of Embryonic Corpora Allatamentioning

confidence: 99%

Allatostatin inhibition and farnesol stimulation of corpus allatum activity in embryos of the viviparous cockroach, Diploptera punctata

Schal

1996

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Control of cell proliferation in the corpora allata during the reproductive cycle of the cockroachDiploptera punctata

Tsai

et al. 1996

Unlike in Blettella germanica and Supella longipalpa, the corpora allata (CA) of Diploptera punctata exhibited cyclic changes in cell number during the reproductive cycle. In mated females, a wave of DNA synthesis followed by mitosis resulted in a significant increase in CA cell number from about 9,000 cells on day 0 to 12,000 cells at ovulation on day 8. Subsequently, the number of cells per CA underwent a gradual decline to about 10,000 cells by day 64. During this long period of gestation, mitotic activity was undetectable (by colchicine arrest) and pycnotic nuclei were frequently observed by transmission electron microscopy. Just before parturition on day 72 another mitotic wave was detected and CA cell number increased again. The early wave of CA cell proliferation could be postponed by delaying mating or abolished by maintaining females as virgins. Neural disconnection of the CA from the brain mimicked the effect of mating, suggesting that enhanced cell proliferation is permitted by the removal of inhibitory signals from cerebral neurosecretory cells. The proliferative activities after mating were neither abolished by ovariectomy, which suppressed the normal increase in JH synthesis, nor elevated by unilateral allalectomy, which doubled the rates of JH synthesis in the remaining CA. These data corroborate previous results (Szibbo and Tobe, 1981a; Tobe et al., 1984; Johnson et al., 1993) and suggest that waves of cell proliferation and JH synthesis, though simultaneous, are regulated independently by inhibitory signals from cerebral neurosecretory cells. © 1996 Wiley‐Liss, Inc.

Allatostatin inhibition and farnesol stimulation of corpus allatum activity in embryos of the viviparous cockroach,Diploptera punctata

Schal

1996

Juvenile hormone (JH) biosynthesis by corpora allata (CA) from embryos of the cockroach Diploptera punctata was measured at four stages during the latter half of embryogenesis. Individual glands from 32‐day‐old embryos that had completed 49% of embryonic development synthesized 0.3 pmol JH III h−1. By day 46 (70% development) gland activity rose to 1.1 pmol JH h−1, but on subsequent days JH synthetic rates declined, measuring only 0.8 pmol h−1 on day 56 (86% development) and 0.5 pmol h−1 on day 60 (92% development). Differences in JH biosynthesis by CA from different‐aged embryos were more evident when gland activity was corrected for either corpus allatum cell number, which increased progressively from fewer than 200 cells per gland on day 32 to almost 700 cells per gland on day 60, or embryo mass, which increased from 1.6 mg per embryo on day 32 to 10.8 mg per embryo on day 60. JH biosynthetic rates were significantly inhibited in a medium containing 10−8 M Dip‐allatostatin 7 which suppressed CA activity by 68, 83, 76, and 51% on days 32, 46, 56, and 60, respectively. In all embryonic stages JH production was significantly stimulated by incubation of glands with 200 μM farnesol, a late precursor in the JH biosynthetic pathway. © 1996 Wiley‐Liss, Inc.