Prothoracicotropic hormone in Manduca sexta: localization by a larval assay (original) (raw)
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Proceedings of the National Academy of Sciences, 1979
The distribution of prothoracicotropic hormone in the pupal brain of Manduca sexta has been determined by an in vitro assay for prothoracic gland activation. Prothoracicotropic activity was observed in both the brain and retrocerebral complex, but predominantly in the dorosolateral regions of the protocerebrum. Of the two groups of neurosecretory cells present in this area of the brain, only the two lateral type III neurosecretory cells exhibited significant prothoracicotropic hormone activity. Further analysis revealed that the neurohormone was localized in only one of the two type III cells, suggesting that a single neurosecretory cell in each hemisphere is the source of the hormone at the stage examined (day 0). Prothoracicotropic hormone activity was detected in both the corpora allata and the corpora cardiaca, but the corpora allata contained 2 to 9 times the activity of the corpora cardiaca, depending on developmental stage. The significantly higher level of activity in the co...
Journal of Insect Physiology, 1986
A titre of the total prothoracicotropic hormone (PTTH) activity in the brain of Marzduca sextu was determined at 24-h intervals during the 4th and Sth-larval instars, and early pupal-adult development using an in vitro assay which monitors stimulation of ecdysone synthesis by prothoracic glands in response to FTTH. The titre increases during development in a stepwise manner at those times when PITH release occurs, suggesting that regulation of the synthesis and/or transport of the neurohormone may be linked to its releiise. By contrast, significant decreases in the F'TTH titre were not observed just after times of its release. The relative amounts of the two molecular forms of PTTH, big and small, in brains were determined at times during development just prior to periods of PTTH release, i.e. day 3 of the last-larval instar and day 1 of the pupal period. In the larval brain big PTTH is the principal hormone present, giving it a ratio to small PTTH of 3.9: 1. In the pupal brain, where total PTTH activity has increased about 5-fold over that of the larval brain, the amount of big PTTH was not significantly greater than in larval brains, whereas the amount of small PTTH has increased by 6-fold. This results in a big to small ratio of 0.95 : 1. These changes in the ratios of the two neuropeptides, which appear to be modulated by the light-dark cycle under which the insect develops, may be involved in the regulation of the postembryonic development of Munduca.
Physical characteristics of the cerebral big prothoracicotropic hormone fromManduca sexta
Experientia, 1994
The prothoracicotropic hormones (PTTHs) are cerebral peptides that control insect postembryonic development by stimulating the prothoracic glands to synthesize ecdysteroids. In Manduca sexta, the tobacco hornworm, two classes of PTTH are distinguished by their Mr, small (ca. 7 kDa) and big PTTH (ca. 25-30 kDa). Little is known about the physical nature of the PTTHs and this study takes a first step towards defining characteristics of the Manduca big PTTH. The neurohormone has a Stokes radius of 2.59 nm and a sedimentation coefficient of 2.76 S. Based on these data, an Mr of 29,443.7 and an fifo of 1.27 were calculated. Combined, the physical data reveal Manduca big PTTH is an asymmetrical acidic homodimeric peptide with intra-and intermolecular disulfide bonds.
The Biology of the Prothoracicotropic Hormone Peptidergic Neurons in an Insect
Integrative and Comparative Biology, 1993
SYNOPSIS. The prothoracicotropic hormone and the cerebral peptidergic neurons that produce it have traditionally been thought to have the singular function of acting as a primary effector of insect postembryonic development. Recent investigations of this neuroendocrine axis in the tobacco hornworm, Manduca sexta, are leading to a new view that these peptidergic neurons and their peptide phenotypes may be multifunctional. They may act in different ways depending upon the animal's developmental stage and site of phenotype release. The possibility for this functional diversity of the prothoracicotropic hormone is possibly even greater due to multiple neuronal sites of peptide expression within the central nervous system. Similarly, the L-NSC III may have more functions due to the expression of multiple peptide phenotypes. The data, thus far, have not enabled us to identify additional physiological roles for the peptide, but they have provided insight into the experimental approaches that might be effective in resolving these functions.
A monoclonal antibody to the insect prothoracicotropic hormone
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1988
The prothoracicotropic hormone (PTTH) is an insect cerebral peptide that stimulates the prothoracic glands to produce the steroid hormone ecdysone thus initiating molting and metamorphosis. "Big" PTTH, one of several molecular forms of the neurohormone, was isolated from brains of the tobacco hornworm Manduca sexta, and fractionated by high-pressure liquid chromatography (HPLC) for use in antibody production. A murine polyclonal antiserum and a monoclonal antibody (MAb) have been generated using this highly purified preparation of big PTTH. Antisera and hybridoma supernatants were screened with an indirect, brain whole-mount immunocytological assay, and antibody specificity was confirmed by immunocytological, ELISA, and functional criteria. In brain whole-mount preparations, the MAb (A2H5) and antiserum specifically immunostained the lateral protocerebral neurosecretory cells (L-NSC III), the prothoracicotropes, which produce PTTH. This immunostaining was blocked by preads...
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2012
Prothoracicotropic hormone (PTTH) is a brain neurohormone that has been studied for over 80 years. The only known target of PTTH is the prothoracic glands (PGs) of larvae, which synthesize the insect molting hormones (ecdysteroids) and a massive literature exists on this axis. The PGs degenerate around the time of adult emergence, yet presence of PTTH has been reported in the brains of several adult insects. Using an in vitro bioassay system, we confirm that PTTH is present in the adult female brain of Rhodnius prolixus. The material is electrophoretically, immunologically and biologically indistinguishable from larval PTTH. The amount of PTTH in the brain shows a daily rhythm during egg development. We show that brains in vitro release PTTH with a daily rhythm over this period of time. PTTH is released at each scotophase. This is the first report that PTTH is released from the adult brain and functions as a hormone, inviting explanation of its function. Larval PTTH is also known to be released with a daily rhythm, and the clock in the brain controls both larval and adult rhythms. The potential significance of rhythmic PTTH release in female adults is discussed in relation to the regulation of ecdysteroids, egg development and the concept of internal temporal order.
In vitro activation of insect prothoracic glands by the prothoracicotropic hormone
Proceedings of the National Academy of Sciences, 1979
An in vitro assay for the prothoracicotropic hormone has been developed that utilizes an ecdysone radioimmunoassay to quantify the increase in the rate of ecdysone synthesis elicited by the neurohormonal activation of the prothoracic glands. The rapidity, reproducibility, and accuracy of the assay were maximized by using one member of a gland pair as the control and the other as the test gland. This was possible because the basal rates of ecdysone synthesis by the members of a gland pair were equivalent. Activation was demonstrated to be dose dependent and specific, with prothoracicotropic hormone activity present only in homogenates of brain. The in vitro activation of the prothoracic glands was verified with the Manduca bioassay for the prothoracicotropic hormone in which the morphological responses to the hormone were correlated with increased in vivo ecdysone titers. These results provide unequivocal evidence that the activation of the prothoracic glands by the prothoracicotropi...