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A G Scott

Publications and source records attributed to A G Scott.

At least 19 recordsLinked to original sources
PubMed1995

The sulfakinins of the blowfly Calliphora vomitoria. Peptide isolation, gene cloning and expression studies.

The nonapeptide, Phe-Asp-Asp-Tyr(SO3)-Gly-His-Met-Arg-Phe-NH2 was isolated from heads of the blowfly Calliphora vomitoria. Designated callisulfakinin I, the peptide is identical to the earlier known drosulfakinin I of Drosophila melanogaster and to neosulfakinin I of Neobellieria bullata. It belongs to the sulfakinin family, all known members of which (from flies, cockroaches and locusts) have the C-terminal heptapeptide sequence Asp-Tyr(SO3)-Gly-His-Met-Arg-Phe-NH2. The callisulfakinin gene of C. vomitoria was cloned and sequenced. In addition to callisulfakinin I, the DNA revealed a coding sequence for the putative tetradecapeptide. Gly-Gly-Glu-Glu-Gln-Phe-Asp-Asp-Tyr-Gly-His- Met-Arg-Phe-NH2, callisulfakinin II. However, this peptide was not identified in the fly head extracts. Confocal laser scanning immunocytochemical studies with antisera raised against the synthetic undecapeptide C-terminal fragment of drosulfakinin II from D. melanogaster, Asp-Gln-Phe-Asp-Asp-Tyr(SO3)- Gly-His-Met-Arg-Phe-NH2, revealed only four pairs of sulfakinin neurones in the brain of C. vomitoria and no others anywhere else in the neural, endocrine or gut tissues. In situ hybridisation studies with a digoxigenin-labelled sulfakinin gene probe (from the blowfly Lucilia cuprina) also revealed only four pairs of neurones in the brain. The perikarya of two pairs of cells are situated medially in the caudo-dorsal region, close to the roots of the ocellar nerve. The other perikarya are slightly more posterior and lateral. Although it has been suggested by several authors that the insect sulfakinins are homologous to the vertebrate peptides gastrin and cholecystokinin, such arguments (based essentially on C-terminal structural similarities) do not take account of important differences in the C-terminal tetrapeptide. His-Met-Arg-Phe-NH2 in the sulfakinins, compared with Trp-Met-Asp-Phe-NH2 in gastrin and cholecystokinin. Furthermore, whereas the sulfakinin neurons of C. vomitoria are small in number and have a very specialised location, a greater number of cells throughout the nervous system react positively to gastrin/cholecystokinin antisera. Chromatographic profiles of the present study also revealed peaks of gastrin/cholecystokinin-immunoreactive material separate from the sulfakinin peptides. This evidence suggests that the insect and vertebrate peptides may not necessarily be homologous.

Amino Acid Sequence↗
PubMed1995

Isolation, identification and functional significance of [Hyp2]Met-callatostatin and des Gly-Pro Met-callatostatin, two further post-translational modifications of the blowfly neuropeptide Met-callatostatin.

Two post-translationally modified neuropeptides of the Met-callatostatin (Gly-Pro-Pro-Tyr-Asp-Phe-Gly-Met-NH2) family have been identified from head extracts of the blowfly Calliphora vomitoria. They are the octapeptide, [Hyp2]Met-callatostatin, (Gly-Hyp-Pro-Tyr-Asp-Phe-Gly-Met-NH2) and the truncated hexapeptide, des Gly-Pro Met-callatostatin (Pro-Tyr-Asp-Phe-Gly-Met-NH2). The existence of the [Hyp2]Met-callatostatin variant, in addition to the previously identified [Hyp3]Met-callatostatin peptide, suggests that the motif for prolyl hydroxylation in C. vomitoria is more variable than those known from mammalian and other invertebrate studies where, in those regulatory peptides containing a pair of adjacent prolyl residues so far studied, e.g., bradykinin, and the mosquito peptide Aea HP-I, only one of the pair (the second) is known to undergo hydroxylation. The truncated hexapeptide, des Gly-Pro Met-callatostatin could be produced as a result of the action of a dipeptidyl peptidase II type of enzyme which is known from mammalian studies to be unique in its ability to cleave between the two prolyl residues of an Xaa-Pro-Pro- sequence, where Xaa is any unprotected NH2-terminal amino acid. This enzyme is, however, considered unlikely to be able to cleave the Gly-Hyp-Pro-sequence, which would suggest a functional significance for such a post-translational modification. For this reason, it is of interest that [Hyp2]Met-callatostatin (and earlier, [Hyp3]Met-callatostatin) have been shown to be potent inhibitors of the spontaneous contractions of the hindgut of C. vomitoria (biphasic dose-response curve with IC50 values of 10(-14) M and 10(-7) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Isolation, structure, and activity of -Phe-Met-Arg-Phe-NH2 neuropeptides (designated calliFMRFamides) from the blowfly Calliphora vomitoria.

Thirteen neuropeptides varying in length from 7 to 11 residues and ending C-terminally in -Phe-Met-Arg-Phe-NH2 (calliFMRFamides 1-13) and one dodecapeptide ending in -Met-Ile-Arg-Phe-NH2 (calliMIRFamide 1) have been isolated from thoracic ganglia of the blowfly Calliphora vomitoria. Different repeating patterns of amino acid sequences enable the peptides to be arranged into distinct groups. One such group of five nonapeptides has the sequence Xaa-Pro-Xaa-Gln-Asp-Phe-Met-Arg-Phe-NH2. Three peptides in this group, with the N-terminal tripeptide sequences Thr-Pro-Gln-, Thr-Pro-Ser-, and Ser-Pro-Ser-, are able to induce fluid secretion from the isolated salivary gland of Calliphora at a concentration of 0.1 to 1 nM. However, two other members of this group with the N-terminal tripeptide sequences Lys-Pro-Asn- and Ala-Pro-Gly-, the latter being the most abundant peptide isolated, were inactive in this assay, as were all the other peptides isolated. This indicates that the N terminus (in addition to the C terminus as previously found for FMRFamides of other organisms) is crucial for at least some biological activities.

Amino Acid Sequence↗
PubMed1992

Site characterization for radon supply potential: a progress review.

"Radon-resistant" house foundations were developed by 1981, but additional construction costs made it undesirable to require them unless necessary. The survey methods used then were labor-intensive and cost so much that it was impractical to identify "radon-prone" areas by nationwide surveys. A cheaper method was required to show where radon-resistant foundations were needed. Information available in 1981 suggested that unusual soil conditions were needed to produce high radon concentrations in houses. If these conditions could be identified, elevated radon concentration levels could be predicted from soil measurements at a lower cost than a radon-in-housing survey. Recent radon surveys show that near-surface bedrock or clay soils, which cover most of the continent, are radon-prone. The measurement methods cannot be used in these soils. The cost of radon surveys has been greatly reduced over the past 10 y. Radon-prone areas can now be identified by radon surveys at a lower cost than soil measurements, and the cost of radon-resistant foundations has been reduced. These developments have removed most of the financial incentive for developing soil-based site classification methods. The priority task now is to encourage the adoption of radon-resistant foundations in radon-prone areas.

Air Pollutants, Radioactive↗
PubMed1991

Chromatographic characterisation and biological activity of neuropeptides immunoreactive to antisera against Met5-enkephalin-Arg6-Phe7 (YGGFMRF) extracted from the blowfly Calliphora vomitoria (Diptera).

Neuropeptides identified with a radioimmunoassay specific for the C-terminus of Met5-enkephalin-Arg6-Phe7 (YGGFMRF) have been extracted from nervous tissues of the blowfly Calliphora vomitoria and also from whole flies. Chromatographic characterisation, based on criteria of molecular weight, charge and hydrophobicity, reveals a complex multiplicity of immunoreactive peptides. Variations in the amounts and types of peptides found within different nervous tissues is evidence that the cellular precursor processing is selective. Physiological studies on the isolated blowfly salivary gland show that synthetic YGGFMRF is a potent secretagogue with a maximal rate of fluid secretion induced at a concentration of between 10(-13) and 10(-12) M. The tetrapeptide comprising the last four residues of the C-terminus of YGGFMRF, Phe-Met-Arg-Phe, is equally potent. However, the carboxyamidated variants, YGGFMRF-NH2 and the molluscan cardioacceleratory peptide FMRF-NH2, as well as the opioid peptides Met5- and Leu5-enkephalin, have no activity. Partially purified YGGFMRF-immunoreactive peptides from the blowfly have ED50 values in the bioassay approximating to 0.3 thoracic ganglion, 2.1 hypocerebral ganglion and 3.0 brain equivalents.

Amino Acid Sequence↗
PubMed1989

Effects of [D-Ala2] Met-enkephalinamide, a Met-enkephalin analog, on delayed response by squirrel monkeys.

Squirrel monkeys were tested on an indirect spatial delayed response task after subcutaneous injections of either physiological saline, 100, or 500 microgram/kg [D-Ala2] methionine enkephalinamide (DAME). During Experiment 1 monkeys completed two-choice delayed response problems with 0-, 6-, 12- and 18- sec delays; DAME significantly enhanced performance at 18-sec delays but not for the shorter delay. During Experiment 2, monkeys performed a nine-choice spatial delayed response task with 0-, 4- and 8-sec delays. In Experiment 2, low but not high doses of DAME impaired performance. Memory functions represented by a bias-free performance measure paralleled percentage correct in both experiments. Therefore, DAME effect, in enhancing and in impairing performance, were not attributable to changes in the relative number of systematic spatial errors (positional win-shift; lose-stay, position perseveration, and position preference).

Animals↗
PubMed1983

Polynesian bronchiectasis.

Six Polynesian children aged 8-14 years with recurrent lower respiratory infections and abnormal lung mucociliary clearance were assessed for immuno-deficiency. Measurements were made in these 6 children and in 21 healthy Polynesians of serum immunoglobulins (IgG, IgM, IgA) and complement components (C3, C4), leucocyte function tests, and T and B cell populations. A further 8 Polynesian bronchiectatics were tested for sputum secretory-IgA. There was no evidence of S-IgA deficiency and 4 had high levels. There was no evidence of immunodeficiency. Nasal epithelium was obtained from 6 children using a cytology brush and ciliated epithelium was obtained in only 4. The ultrastructure was normal although few cilia were examined.

Adolescent↗
PubMed1983

Radon daughter deposition velocities estimated from field measurements.

The surface deposition rate (plateout) of unattached radon daughters was estimated from simple surface activity measurements in a number of occupied buildings, and found to be about one third of the lowest value measured in diffusion tube experiments. This low value was confirmed by surface deposition and activity measurements made in a commercial building with high radon levels, which also showed that the deposition rate was higher on walls than on floors or tables. Predictions of the ratio between airborne and surface-deposited radon daughter activity using the estimated surface deposition rate were close to the ratios observed in occupied homes. Refinements to existing models are required to explain the variability of deposition rate with surface orientation.

Housing↗
PubMed1980

Endoscopic biopsy in the diagnosis of peripheral denervation of the bladder.

Endoscopic biopsies of the bladder were stained using a simple neurohistochemical technique to demonstrate the normal cholinergic innervation. The same technique was used on patients in whom a peripheral neuropathic bladder was suspected and clear evidence of denervation obtained. It is suggested that the technique be applied to all cases where peripheral denervation is a possibility to assist in diagnosis and to select cases where long-term urological follow-up is mandatory.

Aged↗