The molting gland of the cockroach Periplaneta americana: secretory activity and its regulation

Richter, Klaus; Böhm, Gustav‐Adolf

doi:10.1016/s0306-3623(96)00521-6

Cited by 16 publications

(6 citation statements)

References 13 publications

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“…By contrast, the only PG-innervating neurons in Drosophila produce PTTH, which functions as a hormone in many other insects, to upregulate ecdysteroidogenesis (Siegmund and Korge, 2001; McBrayer et al, 2007). Positive regulation of ecdysteroidogenesis by direct innervation of the PG has also been reported in the American cockroach (Richter and Gersch, 1983; Richter and Bohm, 1997). These reports from different insects clearly indicate a more complex role of the innervation of the PG than initially thought.…”

Section: Discussionmentioning

confidence: 65%

Bombyx orcokinins are brain‐gut peptides involved in the neuronal regulation of ecdysteroidogenesis

Yamanaka

Roller

Žitňan

et al. 2010

J of Comparative Neurology

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Biosynthesis of ecdysteroids, the insect steroid hormones controlling gene expression during molting and metamorphosis, takes place primarily in the prothoracic gland (PG). The activity of the PG is regulated by various neuropeptides. In the silkworm Bombyx mori, these neuropeptides utilize both hormonal and neuronal pathways to regulate the activity of the PG, making the insect an excellent model system to investigate the complex signaling network controlling ecdysteroid biosynthesis. Here we report another group of neuropeptides, orcokinins, as neuronal prothoracicotropic factors. Using direct mass spectrometric profiling of the axons associated with the PG, we detected several peptide peaks which correspond to orcokinin gene products in addition to the previously described Bommo-FMRFamides (BRFas). In situ hybridization and immunohistochemistry revealed that orcokinins are produced in the prominent neurosecretory cells in the ventral ganglia, as well as in numerous small neurons throughout the central nervous system and in midgut endocrine cells. One of the two pairs of BRFa-expressing neurosecretory cells in the prothoracic ganglion coexpresses orcokinin, and these neurons project axons through the transverse nerve and terminate on the surface of the PG. Using an in vitro PG bioassay, we show that orcokinins have a clear prothoracicotropic activity and are able to cancel the static effect of BRFas on ecdysteroid biosynthesis, whereas the suppressive effect of BRFas on cAMP production remained unchanged in the presence of orcokinins. The discovery of a second regulator of PG activity in these neurons further illustrates the potential importance of the PG innervation in the regulation of insect development. Additional supporting information may be found in the online version of this article. Insects are an ideal model system for studying how the regulatory mechanisms of developmental timing are coordinated with growth. The developmental transitions of insects (i.e., molting and metamorphosis) are strictly regulated by the steroid hormones known as ecdysteroids. The biosynthesis of ecdysteroids, referred to as ecdysteroidogenesis, occurs predominantly in the prothoracic gland (PG) (Gilbert et al., 2002). The activity of the PG is regulated by various neuropeptides including the prothoracicotropic hormone (PTTH), which is produced in cerebral neurosecretory cells (Ishizaki and Suzuki, 1994;Gilbert et al., 2002;Marchal et al., 2010). The loss of PTTH in Drosophila melanogaster, for example, leads to a delay in metamorphosis due to a low ecdysteroid titer, and the extended feeding period gives rise to bigger pupae and adults (McBrayer et al., 2007;Rewitz et al., 2009b). Identification of the regulators of the PG activity and investigation of their functions are thus important for understanding the regulatory mechanisms of growth and developmental timing in insects. Such studies may also shed light on the developmental transition mechanisms of metazoans in general. HHS Public AccessThe silkworm Bombyx mori,...

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Section: Discussionmentioning

confidence: 65%

Bombyx orcokinins are brain‐gut peptides involved in the neuronal regulation of ecdysteroidogenesis

Yamanaka

Roller

Žitňan

et al. 2010

J of Comparative Neurology

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“…The release of PTTH from the brain controls the biosynthesis of ecdysone in both holometabolous and hemimetabolous insects (Ishizaki and Suzuki 1994;Richter and Böhm 1997;Steel and Vafopoulou 2006). PTTH has a high Fig.…”

Section: Discussionmentioning

confidence: 99%

Putative regulatory mechanism of prothoracicotropic hormone (PTTH) secretion in the American cockroach, Periplaneta americana as inferred from co-localization of Rab8, PTTH, and protein kinase C in neurosecretory cells

2009

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Small GTPases of the Rab family act as essential regulators of vesicle transport pathways, including the exocytosis of neurohormones. These processes are not well-understood in insects. To address the physiological function of Rab proteins and their phosphorylation in insect neurosecretion, Rab8-like, prothoracicotropic hormone (PTTH)-like, and protein kinase C (PKC)-like immunohistochemical reactivities (-ir) were investigated in the brain of the American cockroach, Periplaneta americana. All the antibodies tested reacted with neurons in the pars intercerebralis, corpora cardiaca, and nervi corporis allati I. Double-labeling experiments demonstrated that all PTTH-ir were colocalized with Rab8-ir and PKC-ir in the pars intercerebralis, although exclusive reactivity was present to antisera against Rab8 or PKC. These findings support the notion that Rab8-like antigen is phosphorylated by PKC, and that this phosphorylation is involved in the axonal transport and secretion of PTTH in this species.

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“…At all time points examined in the last instar of the cockroach, the amount of 3DE released by the prothoracic gland exceeded that of ecdysone. The largest differences in 3DE and ecdysone content (6-8:1) produced by the prothoracic gland are in the middle of the last nymphal stage (14th to 17th day, near the head critical period; Richter et al, 1995), and after the 25th day (before the main peak of ecdysteroid production; Richter and Böhm, 1997). In the last instar larvae of S. littoralis, the ratio of 3DE to ecdysone at the end of the larval stage is 4:1 (Chen et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

3-dehydroecdysone secretion by the molting gland of the cockroach,Periplaneta americana (L.)

Richter

Böhm

Leubert

1999

Arch. Insect Biochem. Physiol.

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Prothoracic glands of Periplaneta americana were tested under in vitro conditions for their ability to release 3‐dehydroecdysone (3DE) besides ecdysone. 3DE was identified by RIA after conversion to ecdysone by a ketoreductase‐containing hemolymph preparation as well as in HPLC fractions of incubation medium by an antiserum with affinity to 3DE and ecdysone. The ratio of 3DE to ecdysone secreted into the culture medium was found to vary between 2:1 and 7:1, depending on the period in the last nymphal instar. Enzyme activity of 3β‐ketoreductase showed fluctuations that coincided with the hemolymph ecdysteroid titre. Homogenates of prothoracic glands do not contain ecdysone but contain 3DE. Nevertheless the glands release 3DE as well as ecdysone under in vitro conditions. Different sites where conversion of 3DE to ecdysone takes place are discussed. Arch. Insect Biochem. Physiol. 41:107–116, 1999. © 1999 Wiley‐Liss, Inc.

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The molting gland of the cockroach Periplaneta americana: secretory activity and its regulation

Cited by 16 publications

References 13 publications

Bombyx orcokinins are brain‐gut peptides involved in the neuronal regulation of ecdysteroidogenesis

Bombyx orcokinins are brain‐gut peptides involved in the neuronal regulation of ecdysteroidogenesis

Putative regulatory mechanism of prothoracicotropic hormone (PTTH) secretion in the American cockroach, Periplaneta americana as inferred from co-localization of Rab8, PTTH, and protein kinase C in neurosecretory cells

3-dehydroecdysone secretion by the molting gland of the cockroach,Periplaneta americana (L.)

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