Prothoracicotropic hormone

A related role of the insect corpora allata is to store and release the prothoracicotropic hormone, a... 

Bioassays commonly provide the initial means of detecting neuropeptide activity. The factor(s) responsible for this activity are assigned names reflecting the functions detected with the bioassay (e.g., adipoianetic hormone, AKH diuretic hormone, DH eclosion hormone, EH pheromone biosynthesis activating neuropeptide, PBAN prothoracicotropic hormone, PTTH and so forth). As more of these factors are discovered and characterized, not only are biologic ... 

Prothoracicotropic hormone (Bombyx PTTH) of the silkworm, Bombyx mori, was extracted from adult heads. Bombyx PTTH is suggested to be a glyco-peptide and consists of two essentially identical subunits. Amino acid sequencing and cDNA analysis revealed the whole amino acid sequence of the subunit, composed of 104-109 residues. Bombyx PTTH stimulated adult development in brainless Bombyx pupae at a dose of ca. 0.1 ng and also enhanced the release of ecdysone in vitro at a concentration of 10 M. Immunohistochemistry and in situ hybridization showed that Bombyx PTTH was transcribed and translated in two pairs of dorso-lateral neurosecretory cells in the brain. 

The pupation factor, discovered by Kopec (1.21 was subsequently demonstrated in the commercial silkworm, Bornbyx mori, and eventually isolated and sequenced (see review by Kataoka et al., this volume). It is now known as the prothoracicotropic hormone (PTTH), and it exists as a family of neuropeptides with two molecular mass ranges in B. mori (small, ca. 4 kD and large, ca. 22 kD). The small forms have recently been named "bombyxins" C. Anotiier lepidopteran, the tobacco homworm, Manduca sexta, has received considerable attention in the isolation, mode of action, and cellular localization of PTTH (10-141 Studies with... 

The prothoracicotropic hormones that activate the synthesis of ecdysone in Lepidoptera are highly species-specific, unlike other insect neuropeptides. If something can... 

Molting, which is defined as the shedding of an outer covering as part of a periodic process of growth, is central to the development of insects. Release of ecdysteroids, or molting hormones, from the prothoracic glands is controlled by a neuropeptide called the prothoracicotropic hormone (PTTH) produced by neurosecretory cells and released by corpora cardiaca. 

In insects and in crustaceans, the synthesis of both ecdysteroids and JH/MF are subject to control by neuropeptides. Although ecdysteroids are considered to be growth promoting hormones in both insects and crustaceans, these steroid hormones are differently regulated in the two taxa. In insects, the synthesis and release of ecdysteroids from the prothoracic gland is positively regulated by the prothoracicotropic hormone (PTTH) which is synthesized in neurosecretory cells of the brain and released from the CA [37]. PTTH was first completely identified in B. 

Bombyxin, an insect brain peptide (Mr 5 kDa) with structural similarity to insulin. Bombyxin exists in various molecular forms (I-V). The heterodimers of the A and B chains show about 50% and 30% identity to the A and B chains of human insulin. Bombyxin stimulates, together with the prothoracicotropic hormone (PTTH), the synthesis and release of ecdysone. It has been reported that bombyxin is a growth factor for wing imaginal disks in Lepi-doptera [M. Iwami, Zool. Sci. 2000,17,1035 ... 

---