A vertical array of five hydrophones was used to measure the acoustic field in the vertical plane of singing humpback whales. Once a singer was located, two swimmers with snorkel gear were deployed to determine the orientation of the whale and position the boat so that the array could be deployed in front of the whale at a minimum standoff distance of at least 10 m. The spacing of the hydrophones was 7 m with the deepest hydrophone deployed at a depth of 35 m. An eight-channel TASCAM recorder with a bandwidth of 24 kHz was used to record the hydrophone signals. The location (distance and depth) of the singer was determined by computing the time of arrival differences between the hydrophone signals. The maximum source level varied between individual units in a song, with values between 151 and 173 dB re 1 microPa. One of the purposes of this study was to estimate potential sound exposure of nearby conspecifics. The acoustic field determined by considering the relative intensity of higher frequency harmonics in the signals indicated that the sounds are projected in the horizontal direction despite the singer being canted head downward anywhere from about 25 degrees to 90 degrees. High-frequency harmonics extended beyond 24 kHz, suggesting that humpback whales may have an upper frequency limit of hearing as high as 24 kHz.

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The identification of potent, highly selective orally bioavailable ghrelin receptor inverse agonists from a spiro-azetidino-piperidine series is described. Examples from this series have promising in vivo pharmacokinetics and increase glucose-stimulated insulin secretion in human whole and dispersed islets. A physicochemistry-based strategy to increase lipophilic efficiency for ghrelin receptor potency and retain low clearance and satisfactory permeability while reducing offtarget pharmacology led to the discovery of 16h. Compound 16h has a superior balance of ghrelin receptor pharmacology and off-target selectivity. On the basis of its promising pharmacological and safety profile, 16h was advanced to human clinical trials.

Peptidic glucagon antagonists have been shown to lower blood glucose levels in diabetic models (1-3), but attempts to identify small molecular weight glucagon receptor-binding antagonists have met with little success. Skyrin, a fungal bisanthroquinone, exhibits functional glucagon antagonism by uncoupling the glucagon receptor from adenylate cyclase activation in rat liver membranes (1). We have examined the effects of skyrin on cells transfected with the human glucagon receptor and on isolated rat and human hepatocytes. The skyrin used was isolated from Talaromyces wortmanni American Type Culture Collection 10517. In rat hepatocytes, skyrin (30 µmol/l) inhibited glucagon-stimulated cAMP production (53%) and glucose output (IC 50 56 µmol/l). There was no detectable effect on epinephrine or glucagon-like peptide 1 (GLP-1) stimulation of these parameters, which demonstrates skyrin's selective activity. Skyrin was also evaluated in primary cultures of human hepatocytes. Unlike cell lines, which are largely unresponsive to glucagon, primary human hepatocytes exhibited glucagon-dependent cAMP production for 14 days in culture (EC 50 10 nmol/l). Skyrin (10 µmol/l) markedly reduced glucagon-stimulated cAMP production (55%) and glycogenolysis (27%) in human hepatocytes. The inhibition of glucagon stimulation was a specific property displayed by skyrin and oxyskyrin but not shared by other bisanthroquinones. Skyrin is the first small molecular weight nonpeptidic agent demonstrated to interfere with the coupling of glucagon to adenylate cyclase independent of binding to the glucagon receptor. The data presented in this study indicate that functional uncoupling of the human glucagon receptor from cAMP production results in metabolic effects that could reduce hepatocyte glucose production and hence alleviate diabetic hyperglycemia.

The maintenance of genome stability is a fundamental requirement for normal cell cycle progression. The budding yeast Saccharomyces cerevisiae is an excellent model to study chromosome maintenance due to its well-defined centromere and kinetochore, the region of the chromosome and associated protein complex, respectively, that link chromosomes to microtubules. To identify genes that are linked to chromosome stability, we performed genome-wide synthetic lethal screens using a series of novel temperaturesensitive mutations in genes encoding a central and outer kinetochore protein. By performing the screens using different mutant alleles of each gene, we aimed to identify genetic interactions that revealed diverse pathways affecting chromosome stability. Our study, which is the first example of genome-wide synthetic lethal screening with multiple alleles of a single gene, demonstrates that functionally distinct mutants uncover different cellular processes required for chromosome maintenance. Two of our screens identified APQ12, which encodes a nuclear envelope protein that is required for proper nucleocytoplasmic transport of mRNA. We find that apq12 mutants are delayed in anaphase, rereplicate their DNA, and rebud prior to completion of cytokinesis, suggesting a defect in controlling mitotic progression. Our analysis reveals a novel relationship between nucleocytoplasmic transport and chromosome stability.

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Suleske. R T (1998) Structurefunction analysis of a series of glucagon-like peptide-i analogs I Peptide Res 5 1 , 398-409 Abstract We have used NMR in conjunction with measurements of functional bioactivity t o define the receptor-binding structure of glucagon-like peptide-1 (GLP-1.) Identification of the important residues for binding was accomplished by the substitution of amino acids at sites that seemed likely, from an examination of the amino acid sequence and from previously published observations, to be important in the three-dimensional (3D) structure of the molecule. Identification of the receptor-bound conformation of GLP-1, because it is a flexible peptide, required constraint of the peptide backbone into a predetermined 3D structure. Constraint was achieved by the introduction of disulfide bonds and specific side chain-side chain cross-links. The biological relevance of the synthetic structure of each rigidified peptide was assessed by measurement of its ability to bind t o the receptor present on RINm5F cells and to elicit a functional response, cyclic AMP production. NMR solution structures were obtained for the most biologically relevant of these analogs. The results of this study indicated that the residues necessary for the biological activity of GLP-1 occupy approximately three equally-spaced regions of the peptide 3D structure, at the corners of an equilateral triangle whose sides are, at a minimum estimate, 12-15 A. Abbreviations: Acetic acid (AcOH), acetic anhydride (Ac20), acetonitrile (MeCN), Applied Biosystems Inc. (ABI), 2-(I Hbenzotriazol-1 -yl)-1 ,I ,3,3-tetramethyluronium tetrafluoroborate (TBTU), benzotriazole-I -yl-oxy-tris-(dimethylamino)-phosphonium hexafluorophosphate (BOP), t-Butyloxycarbonyl (Boc), correlation spectroscopy (COSY), 1.8-diazabicyclo(5.4.0)undec-7-ene (DBU), dichloromethane (DCM), diethyl ether (ether), 3.4-dihydro-4-0~0benzotriazine-3-oxy ester (DHBT), diisopropylethylamine (DIEA). dimethylformamide (DMF), dimethyl sulfide (DMS). double-Parker et d . Clucagon-like peptide 1 analogs quantum spectroscopy (DQ), double-quantum filtered correlation spectroscopy (DQF-COSY), electrospray mass spectroscopy (ESMS), 9-fluorenylmethoxycarbonyl (Fmoc), 2-( 1 H-benzotriazole-lyl)l,1,3,3,-tetramethyluronium tetrafluoroborate (HBTU), hydrogen fluoride (HF), I-hydroxybenzotriazole (HOBT) p-methyl benzhydrylamine (mBHA), nuclear Overhauser effect spectroscopy (NOESY), N-methylpyrrolidone (NMP), nuclear magnetic resonance (NMR), Root-mean-square deviation (RMSD), reverse-phase high performance liquid chromatography (RP-HPLC), sodium dodecyl sulfate (SDS), triethyl amine (TEA), trifluoroacetic acid (TFA), total correlation spectroscopy (TOCSY), tris(hydroxymethy1)aminomethane (TRIS).GLP-1 is a naturally occurring peptide product of the proglucagon gene. GLP-1 and the closely-related glycineextended peptide GLP-i(7-37), appear to function in vivo as incretins, that is, naturally occurring substances which are released in response to food, and which promote the secretion of insulin (1...