Purification and primary structure of glucagon from ostrich pancreas splenic lobes

The origin and function of the pituitary adenylate cyclase-activating polypeptide (PACAP)/glucagon superfamily

The pituitary adenylate cyclase-activating polypeptide (PACAP)/ glucagon superfamily includes nine hormones in humans that are related by structure, distribution (especially the brain and gut), function (often by activation of cAMP), and receptors (a subset of seven-transmembrane receptors). The nine hormones include glucagon, glucagon-like peptide-1 (GLP-1), GLP-2, glucose-dependent insulinotropic polypeptide (GIP), GH-releasing hormone (GRF), peptide histidine-methionine (PHM), PACAP, secretin, and vasoactive intestinal polypeptide (VIP). The origin of the ancestral superfamily members is at least as old as the invertebrates; the most ancient and tightly conserved members are PACAP and glucagon. Evidence to date suggests the superfamily began with a gene or exon duplication and then continued to diverge with some gene duplications in vertebrates. The function of PACAP is considered in detail because it is newly (1989) discovered; it is tightly conserved (96% over 700 million years); and it is probably the ancestral molecule. The diverse functions of PACAP include regulation of proliferation, differentiation, and apoptosis in some cell populations. In addition, PACAP regulates metabolism and the cardiovascular, endocrine, and immune systems, although the physiological event(s) that coordinates PACAP responses remains to be identified.

Neuropeptide families: evolutionary perspectives

Examination of neuropeptide families can provide information about phyletic relationships and evolutionary processes. In this article the oxytocin/vasopressin family, growth hormone releasing factor (GRF) superfamily and the substance P/tachykinin family have been considered in detail because they have been isolated from an extraordinarily diverse array of species from several vertebrate classes and invertebrate phyla. More important is that the nucleotide sequence of mRNA or cDNA encoding many of these peptides has been determined, which has allowed evolutionary distances to be estimated based on the DNA mutation rate. The origin of a given family lies in a primordial gene that arose many millions of years ago, and through time, exon duplication and insertion, gene duplication, point mutation and exon loss, the family developed into the forms that are now recognised. For example, in birds, GRF and pituitary adenylate cyclase activating peptide (PACAP) are encoded by the same gene, which probably arose as a result of exon duplication and tandem insertion of the ancestral GRF gene. In mammals GRF is the sole product on one gene, and PACAP is the product of a gene that also produces PACAP-related peptide (PRP), which is homologous to GRF. Thus it appears that between birds and mammals the GRF/PACAP gene duplicated: exon loss gave rise to the mammalian GRF gene, while mutation led to the formation of the mammalian PRP/PACAP gene. The neuropeptide Y superfamily is considered briefly, as is cionin, which is an invertebrate peptide that is closely related to the mammalian gastrin/cholecystokinin family.

Developmental changes in serum insulin-like growth factor-I and insulin-like growth factor binding proteins in the turkey embryo

The ontogeny of insulin-like growth factor-I (IGF-I) and ontogeny as well as the molecular nature of the insulin-like growth factor binding proteins (IGFBP) as they relate to embryogenesis and posthatch growth in the turkey have not been reported. In this study, serum samples were harvested from turkey embryos incubated under shell-less and shelled conditions from Day 12 to 28 of incubation. Samples from 3, 6, and 8 wk posthatch were also evaluated. Significant changes in serum IGF-I in shelled embryos were observed in that IGF-I was low in early incubation, peaked at mid-incubation, and returned to levels equivalent to early incubation at hatching. No mid-embryogenesis (Days 14 to 18) increase in serum IGF-I was noted in the shell-less cultures. Embryo weights diverge at Day 18 of incubation, with shell-less embryos being significantly lighter than their age-matched shelled embryos, suggesting a possible relationship between total circulating IGF-I and body weight gain. Three distinct IGFBP were identified in serum from turkey embryos, exhibiting molecular weights of 27, 29, and 69 kDa. During embryonic development, the 29 kDa IGFBP appeared to be the predominant species, with levels peaking on Day 24 of incubation, and being minimally detectable at hatching. Ontogeny of the 29 kDa IGFBP was similar in the shelled and shell-less embryos. The 69-kDa IGFBP-like protein did not appear in the circulation until late in embryogenesis, Day 22 in shell-less and Day 26 in shelled embryos. The 27-kDa IGFBP appeared in late incubation. Similar IGFBP (28, 30, and 69 kDa) were observed in the growing male turkey. The 69-kDa protein did not vary across ages studied, whereas the 28-kDa IGFBP appeared to increase with age. This is the first report describing serum IGF-I and IGFBP in the developing turkey. Turkey IGFBP appear to be regulated by independent events during incubation and posthatch growth.