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Biomedical subjects

A Thorpe

Publications and source records attributed to A Thorpe.

At least 55 records · Page 3Linked to original sources
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

Kynurenine identified as the short-wave absorbing lens pigment in the deep-sea fish Stylephorus chordatus.

A number of deep-sea fish have bright yellow lenses whose coloration is attributable to a variety of largely unidentified short-wave absorbing pigments. Here the pigment of the deep-sea fish Stylephorus chordatus has been isolated and identified by NMR and mass spectroscopy as kynurenine; a pigment also found in the human lens. The degree of this pigmentation is greater in older animals. The fact that the lenses of both a deep-sea fish and man contain the same pigment is of interest, given the vastly different light environments they inhabit.

Animals↗
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↗
PubMed1991

Immunocytochemical mapping of neuronal pathways from brain to corpora cardiaca/corpora allata in the cockroach Diploptera punctata with antisera against Met-enkephalin-Arg6-Gly7-Leu8.

Neuronal circuits in the brain and retrocerebral complex of the cockroach Diploptera punctata have been mapped immunocytochemically with antisera directed against the extended enkephalin, Met-enkephalin-Arg6-Gly7-Leu8 (Met-8). The pathways link median and lateral neurosecretory cells with the corpus cardiacum corpus allatum complex. In females, nerve fibres penetrate the corpora allata and varicosities or terminals, immunoreactive to Met-8, surround the glandular cells. Males differ in having almost no Met-8 immunoreactivity in the corpora allata. The corpora cardiaca of both males and females are richly supplied with Met-8 immunoreactive material, in particular in the 'cap' regions immediately adjacent to the corpora allata. A similarity in the amino-acid sequences of Met-8 and the C-terminus of the recently characterised allatostatins of D. punctata suggests that the pathways identified with the Met-8 antisera may be the same as those by which the allatostatins are transported from the brain to the corpus allatum. In comparative studies on the blowfly Calliphora vomitoria, similar neuronal pathways have been identified except that no sexual dimorphism with respect to amounts of immunoreactive material within the corpus allatum has been observed. These results suggest a possible homology in the neuropeptide regulation of the gland.

Amino Acid Sequence↗
PubMed1991

Ultraviolet-sensitive cones in the goldfish.

Goldfish have been shown behaviourally to have ultraviolet sensitivity. We have now identified by microspectrophotometry a population of small single cones in the goldfish retina that contain a visual pigment maximally sensitive around 355-360 nm.

Animals↗
PubMed1990

Distribution of functional significance of Met-enkephalin-Arg6-Phe7- and Met-enkephalin-Arg6-Gly7-Leu8-like peptides in the blowfly Calliphora vomitoria. II. Immunocytochemical mapping of neuronal pathways in the retrocerebral complex and thoracic ganglion.

Neuronal pathways in the retrocerebral complex and thoracico-abdominal ganglionic mass of the blowfly Calliphora vomitoria have been identified immunocytochemically with antisera against the extended-enkephalins, Met-enkephalin-Arg6-Phe7 (Met-7) and Met-enkephalin-Arg6-Gly7-Leu8 (Met-8). Neurons of the hypocerebral ganglion, immunoreactive to Met-8, have axons in the crop duct nerve and terminals in muscles of the crop and its duct. Certain neurons of the hypocerebral ganglion are also immunoreactive to Met-7, and axons from these cells innervate the heart. Met-8 immunoreactive nerve terminals invest the cells of the corpus allatum. The source of this material is believed to be a single pair of lateral neurosecretory cells in the brain. There is no Met-7 immunoreactive material in the corpus allatum. In the corpus cardiacum neither Met-7 nor Met-8 immunoreactivity is present in the cells. However, in the neuropil of the gland certain fibres, with their origins elsewhere, do contain Met-8 immunoreactivity. The most prominent neurons in the thoracic ganglion are the Met-7 immunoreactive ventral thoracic neurosecretory cells, axons from which project to neurohaemal areas in the dorsal neural sheath and also, via the ventral connective, to the brain. Co-localisation studies show that the perikarya of these cells are immunoreactive to antisera raised against several vertebrate-type peptides, such as Met-7, gastrin/cholecystokinin and pancreatic polypeptide. However, their axons and terminals show varying amounts of the peptides, suggesting differential transport and utilisation. Only a few cells in the thoracic ganglion are immunoreactive to Met-8 antisera. These lie close to the nerve bundles supplying the legs. In the abdominal ganglion, Met-8 immunoreactive neurons project to the muscles of the hindgut. This study suggests that the extended enkephalin-like peptides of Calliphora may have a variety of different roles: as neurotransmitter or neuromodulator substances; in the direct innervation of effector organs; and as neurohormones.

Animals↗
PubMed1989

Distribution and functional significance of Met-enkephalin-Arg6-Phe7- and Met-enkephalin-Arg6-Gly7-Leu8-like peptides in the blowfly Calliphora vomitoria. I. Immunocytochemical mapping of neuronal pathways in the brain.

Neuronal pathways immunoreactive to antisera against the extended-enkephalins, Met-enkephalin-Arg6-Phe7 (Met-7) and Met-enkephalin-Arg6-Gly7-Leu8 (Met-8), have been identified in the brain of the blowfly Calliphora vomitoria. Co-localisation with other enkephalins in certain neurons suggests that a precursor similar to preproenkephalin A exists in insects and that differential enzymatic processing occurs as in vertebrates. Co-localisations of the extended-enkephalin-like peptides with other vertebrate-type peptides, including cholecystokinin and pancreatic polypeptide, also occur. The enkephalinergic pathways are specific, comprising a few groups of highly characteristic neurons and areas of neuropil. Of special interest is the finding that parts of the antennal chemosensory and the optic lobe visual systems contain Met-8 immunoreactive neurons. Within the median neurosecretory cell groups, some of the giant neurons show immunoreactivity to Met-8 and others to both Met-8 and Met-7. Fibres from these cells project to the corpus cardiacum and also to the suboesophageal ganglion, where arborisations occur in the tritocerebral neuropil. Co-localisation studies of these cells have shown that at certain terminals, one particular type of peptide is the dominant neuroregulator, whilst at other terminals, within the same cell, a different co-synthesised peptide predominates. Several groups of lateral neurosecretory cells show clearly defined enkephalinergic pathways, most of which have connections with the central body. The complex patterns of immunoreactivity seen in terminals in the different parts of the central body, suggest an important role for the enkephalin-like peptides in the integration of multimodal sensory inputs. The physiological functions of the extended-enkephalin-like peptides in the brain of Calliphora is still unknown, but the anatomical evidence suggests they may have a role similar to that in mammals, where they are thought to control aspects of feeding behaviour.

Animals↗
PubMed1988

Mapping of enkephalin-related peptides in the nervous system of the blowfly, Calliphora vomitoria, and their co-localization with cholecystokinin (CCK)- and pancreatic polypeptide (PP)-like peptides.

The distribution of enkephalin-like immunoreactive material has been studied in the CNS of C. vomitoria. The presence of both Met- and Leu-enkephalin-related peptides is suggested by differential immunostaining with a variety of antisera. Comparisons made between certain of the enkephalin-immunoreactive perikarya, nerve fibres and terminals with cells in corresponding positions as evidenced in previously published neuroanatomical studies of the dipteran brain have suggested specific enkephalinergic pathways. As examples, one Met-enkephalin-immunoreactive neuron appears to link the lobula with the dorsal protocerebrum, and a group of Leu-enkephalin cells in the pars intercerebralis appear to have arborisations in both the central body (fan-shaped body) and the tritocerebral neuropil around the oesophageal foramen. Neuronal pathways of this type indicate that the enkephalin-like peptides of the fly brain are functioning as neurotransmitters and/or neuromodulators. In the thoracic ganglia, symmetrically arranged cells, immunoreactive to both Met- and Leu-enkephalin antisera, are positioned ventrally in pairs on either side of the mid-line in a sagittal plane. Very little immunoreactive material is observed in the neuropil, however, and the source of the accumulation of Leu-enkephalin-immunoreactivity in the dorsal neural sheath is not certain. It is suggested that this material, in contrast to that present in areas of the brain, acts as a neurohormone and that it may have a physiological role following its release into the haemolymph. The enkephalin-like immunoreactive material of certain neurons identified within the brain and thoracic ganglion shows a complex pattern of co-existence with pancreatic polypeptide- and gastrin/cholecystokinin-like peptides.

Animals↗
PubMed1988

Light- and electron-microscopic immunocytochemistry of peptidergic neurons innervating thoracico-abdominal neurohaemal areas in the blowfly.

Ventral thoracic neurosecretory cells (VTNCs) of the blowflies, Calliphora erythrocephala and C. vomitoria, innervating thoracic neuropil and the dorsal neural sheath of the thoracico-abdominal ganglion have been shown to be immunoreactive to a variety of mammalian peptide antisera. In the neural sheath the VTNC terminals form an extensive neurohaemal network that is especially dense over the abdominal ganglia. The same areas are invaded by separate, but overlapping serotonin-immunoreactive (5-HT-IR) projections derived from neuronal cell bodies in the suboesophageal ganglion. Immunocytochemical studies with different antisera, applied to adjacent sections at the light-microscopic level, combined with extensive cross-absorption tests, suggest that the perikarya of the VTNCs contain co-localized peptides related to gastrin/cholecystokinin (CCK), bovine pancreatic polypeptide (PP), Met- and Leu-enkephalin and Met-enk-Arg6-Phe7 (Met-enk-RF). Electron-microscopic immunogold-labeling shows that some of the terminals in the dorsal sheath react with several of the individual peptide antisera, whilst others with similar cytology are non-immunoreactive. In the same region, separate terminals with different cytological characteristics contain 5-HT-IR. Both 5-HT-IR and peptidergic terminals are localized outside the cellular perineurium beneath the acellular permeable sheath adjacent to the haemocoel. Hence, we propose that various bioactive substances may be released from thoracic neurosecretory neurons into the circulating haemolymph to act on peripheral targets. The same neurons may also interact by synaptic or modulatory action in the CNS in different neuropil regions of the thoracic ganglion.

Abdomen↗
PubMed1986

Identification of hormone-producing cells of the endocrine pancreas of the sea bass, Dicentrarchus labrax, by ultrastructural immunocytochemistry.

The hormone-producing cells of the endocrine pancreas of the sea bass Dicentrarchus labrax have been identified by ultrastructural immunocytochemistry. The glucagon cells have "clear" cytoplasm and contain characteristic electron-dense polygonal granules surrounded by a "halo" of electron-lucent material. The insulin cells have numerous, tightly packed, electron-dense granules that are almost twice as large as the peripherally located granules of the somatostatin cells. The pancreatic polypeptide cells have granules with variable electron density. When specific antisera are applied in the peroxidase-anti-per-oxidase immunocytochemical method at the electron microscope level, each of the four types of granule is identified by the resultant overlying immunoreaction deposit. Especially in older fish, a fifth, nonclassified type of cell has been identified within the endocrine pancreatic tissue. These cells have many ramifying processes and contain a mixture of the granules of the four endocrine cell types as well as granules from the exocrine tissue. It is suggested that these cells may be undertaking macrophage activities. A distinct patterned arrangement of the endocrine cell types in both small pancreatic islets and Brockmann bodies is observed. There is a central core of insulin and somatostatin cells surrounded by an outer peripheral layer of glucagon and pancreatic polypeptide cells. A definite functional interrelationship is suggested by this arrangement.

Animals↗
PubMed1984

Immunocytochemical mapping of gastrin/CCK-like peptides in the neuroendocrine system of the blowfly Calliphora vomitoria (Diptera).

The distribution of gastrin/CCK-like immunoreactive material has been studied in the retrocerebral complex of Calliphora. The material reacts with antisera specific for the common COOH terminus of gastrin and CCK but not with N-terminal antisera. The three thoracic ganglia and the fused abdominal ganglia each contain a specific number of symmetrically arranged immunoreactive cells both dorsally and ventrally in pairs on either side of the midline in a sagittal plane. The neuropil of these ganglia also contains a considerable amount of immunoreactive fibres and droplets. Reconstructed axonal pathways suggest that some of the nerve fibres have their origins within the brain and/or the suboesophageal ganglion. Immunoreactive material may also be seen apparently leaving the thoracic ganglion posteriorly via the abdominal nerves, and there is strong evidence of a neurohaemal organ within the dorsal sheath in the region of the metathoracic and abdominal ganglia. There appears to be a direct correlation between the content of peptidergic material of cells and fibres and the age and diet of the flies. The corpus cardiacum contains COOH-terminal specific gastrin/CCK-like material within the intrinsic cells and in the neuropil. It is present also in the cardiac-recurrent nerve entering the corpus cardiacum anteriorly and in the nerves leaving the gland dorsoposteriorly, the aortic or cardiac nerves. It is not observed, however, in the nerves leaving the corpus cardiacum ventroposteriorly, the so-called oesophageal, gastric or crop-duct nerves. The corpus allatum and the hypocerebral ganglion do not contain immunoreactive material of this type. Gastrin/CCK-like and secretin-like immunoreactive materials appear to co-exist in the cells of the corpus cardiacum and co-existence of gastrin/CCK-like and pancreatic polypeptide-like substances occurs within certain cells of the thoracic ganglion.

Animals↗
PubMed1983

Immunocytochemical identification of alpha-endorphin-like material in neurones of the brain and corpus cardiacum of the blowfly, Calliphora vomitoria (Diptera).

A group of the 24-26 paraldehyde fuchsin-positive median neurosecretory cells (MNC) in the pars intercerebralis of the brain of the blowfly, Calliphora vomitoria, has shown immunoreactivity towards three different antibodies to alpha-endorphin, a peptide that corresponds to the amino acid sequence present between residues 61 and 76 of the precursor molecule, beta-lipotropin (beta-LPH). The immunoreactive material could be followed in axons within the median bundle, the tract through which neurosecretory material from the MNC is passed down to the corpus cardiacum (CC). The alpha-endorphin-immunoreactive material was observed leaving the CC in the cardiac-recurrent nerve, dorsal to the proventriculus, in the direction of the abdomen. The cells that contain the alpha-endorphin-like material are different from those of the MNC that contain insulin-, pancreatic polypeptide-, and gastrin/CCK-like peptides. This finding demonstrates the considerable complexity and peptidergic nature of the MNC and constitutes further evidence that morphinomimetic-like peptides are present in the nervous system of invertebrates.

Animals↗
PubMed1983

Cobalt-immunocytochemical identification of peptidergic neurons in Calliphora innervating central and peripheral targets.

Certain neurons of the blowfly, Calliphora erythrocephala, show immunoreactivity to anti-gastrin/cholecystokinin (CCK) COOH terminal specific antisera. However, as is common to immunocytochemical staining, much of the structure of the immunoreactive neurons escapes detection. We describe here whole-neuron identification by backfilling with Co2+ and subsequent silver reduction, combined with immunocytochemistry of the filled cells. Cobalt-silver filled neurons can be examined directly by fluorescence microscopy for the presence of a secondary, rhodamine-conjugated antibody linked to the primary one. Two peptide-containing pathways have been resolved, one leading out of the brain to the corpus cardiacum, the other innervating certain higher brain centres, such as the central body. Both arise from neurosecretory cells of the mid-brain. Immunoreactive peptidergic neurons leading, respectively, to the corpus cardiacum and to the central body have been matched to single nerve cells visualized by Golgi impregnation, cobalt backfilling or focal injection of cobalt into the brain.

Animals↗