Darren B. Parker

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A cDNA that codes for two peptides in the glucagon superfamily has been isolated from sockeye salmon brain. The first peptide is related to growth hormone-releasing hormone (GHRH), which has high sequence similarity with PACAP-related peptide. The second peptide is structurally related to vasoactive intestinal peptide, which is also related to a newly(More)
Growth hormone-releasing hormone (GHRH) and pituitary adenylate cyclase activating polypeptide (PACAP) are two neuropeptides that are associated with the release of pituitary growth hormone. Here a cDNA of 2501 base pairs encoding both a PACAP and a GHRH-like peptide was isolated from a brain cDNA library made from Thai catfish (Clarias macrocephalus). The(More)
The purification of NPY from brains of the American alligator (Alligator mississippiensis) was achieved using reverse-phase high performance liquid chromatography (HPLC). The amino acid sequence was determined using automated Edman degradation as Tyr-Pro-Ser-Lys-Pro-Asp-Asn-Pro-Gly-Glu-(More)
Two forms of gonadotropin-releasing hormone (GnRH) have been purified from brains of the American alligator, Alligator mississippiensis, using reverse-phase high-pressure liquid chromatography (HPLC). The concentration of total GnRH was 8.8 ng/g of frozen brain tissue or 21.1 ng per brain. The amino acid sequence of each form of GnRH was determined using(More)
In the context of two-path convexity, we study the rank, Helly number, Radon number, Caratheodory number, and hull number for multipartite tournaments. We show the maximum Caratheodory number of a multipartite tournament is 3. We then derive tight upper bounds for rank in both general multipartite tournaments and clone-free multipartite tournaments. We show(More)
We present some results on two-path convexity in clone-free regular multipartite tournaments. After proving a structural result for regular multipartite tournaments with convexly independent sets of a given size, we determine tight upper bounds for their size (called the rank) in clone-free regular bipartite and tripartite tournaments. We use this to(More)
We study two-path convexity in bipartite tournaments. For a bipartite tournament , we obtain both a necessary condition and a sufficient condition on the adjacency matrix for its rank to be two. We then investigate 4-cycles in bipartite tournaments of small rank. We show that every vertex in a bipartite tournament of rank two lies on a four cycle, and(More)
We investigate the convex invariants associated with two-path convexity in clone-free multipartite tournaments. Specifically, we explore the relationship between the Helly number, Radon number and rank of such digraphs. The main result is a structural theorem that describes the arc relationships among certain vertices associated with vertices of a given(More)
The collection of convex subsets of a multipartite tournament T forms a lattice C(T). Given a lattice structure for C(T), we deduce properties of T. In particular, we find conditions under which we can detect clones in T. We also determine conditions on the lattice which will imply that T is bipartite, except for a few cases. We classify the ambiguous(More)
An antiserum with conformational specificity to human growth hormone-releasing hormone (hGH-RH 1-44 NH2) was produced and used to develop a radioimmunoassay to detect immunoreactive (ir) GH-RH in brain extracts of salmon, guinea pig, and mouse. Evidence of an immunoreactive GH-RH from salmon brain extracts with a retention time on reverse-phase(More)