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S D Morley

Publications and source records attributed to S D Morley.

At least 37 records · Page 2Linked to original sources
PubMed1992

In situ hybridization of corticotropin-releasing factor-encoding messenger RNA in the hypothalamus of the white sucker, Catostomus commersoni.

In situ hybridization procedure with a 32P-labelled synthetic oligonucleotide probe was used to detect corticotropin-releasing factor-encoding messenger RNA (CRF mRNA) in the hypothalamus of the white sucker, Catostomus commersoni. Adjacent sections were immunostained by a sucker CRF-specific antiserum. CRF mRNA-containing neurons were identified by autoradiography in the magnocellular and parvocellular subdivisions of the preoptic nucleus (PON). Many of these neurons were also immunostained by sucker antiserum, showing the same distribution patterns. These results confirm the presence of CRF mRNA and CRF peptide in the white sucker hypothalamus and support the view that the magnocellular and parvocellular neurons of the PON may be involved in the control of adrenocorticotropic hormone secretion from the pituitary in the white sucker.

Animals↗
PubMed1991

COSMIC(90): an improved molecular mechanics treatment of hydrocarbons and conjugated systems.

Four modifications to the COSMIC molecular mechanics force field are described, which greatly increase both its versatility and the accuracy of calculated conformational energies. The Hill non-bonded van der Waals potential function has been replaced by a two-parameter Morse curve and a new H-H potential, similar to that in MM3, incorporated. Hydrocarbon energies in particular are much improved. A simple iterative Hückel pi-electron molecular orbital calculation allows modelling of conjugated systems. Calculated bond lengths and rotational barriers for a series of conjugated hydrocarbons and nitrogen heterocycles are shown to be as accurate as those determined by the MM2 SCF method. Explicit hydrogen-bonding potentials for H-bond acceptor-donor atom pairs have been included to give better hydrogen bond energies and lengths. The van der Waals radii of protonic hydrogens are reduced to 0.5 A and the energy well depth is increased to 1.0 kcal mol-1. Two new general atom types, N+sp2 and O-sp3, have been introduced which allow a wide variety of charged conjugated systems to be studied. A minimum of parameterisation is required, as the new types are easily included in the Hückel scheme which automatically adjusts bond and torsional parameters according to the defined bond-order relationships.

Computer Simulation↗
PubMed1991

Sodium and potassium ATPase of the teleost fish Catostomus commersoni. Sequence, protein structure and evolutionary conservation of the alpha-subunit.

The alpha-subunit of a Na+/K+ ATPase has been cloned by analysing a lambda gt11 library constructed from polyA+ RNA from the hypothalamic region of the teleost fish Catostomus commersoni (white sucker). The cDNA clone consists of 3853 bp and predicts a protein of 1027 amino-acid residues. Alignment of the sucker sequence with protein sequences previously published for alpha-subunits from various species reveals a high degree of homology throughout the entire sequence containing five potential sites for N-glycosylation, a phosphorylation site and a site for binding fluorescein 5'-isothiocyanate (FITC). A hydropathy profile predicts a secondary structure of the Na+/K+ ATPase alpha-subunit with at least eight membrane-spanning domains. Northern and southern blot analyses suggest the existence of two distinct Na+/K+ ATPase alpha-subunit genes in the sucker genome.

Amino Acid Sequence↗
PubMed1991

Neuropeptide hormone receptors: strategies for identification.

Study of the structure--function relationship of neuropeptide hormone receptors presents a number of technical difficulties associated with the isolation of a given receptor protein in a purified form. A variety of molecular approaches has enabled corresponding cDNA clones to be isolated without the need to embark on protein purification procedures. However, the molecular cloning approach requires that appropriate tools for identifying cDNAs encoding the respective receptor be available. Strategies designed to address this problem will be discussed and include functional expression of neuropeptide hormone receptors in frog oocytes, hybrid depletion and inactivation of receptor-encoding mRNAs by RNase H digestion, polymerase chain reaction (PCR) amplification of cDNAs encoding putative receptors, and expression of transfected receptor genes in cell cultures followed by identification using a cell sorter.

Amino Acid Sequence↗
PubMed1991

Corticotropin-releasing factor (CRF) gene family in the brain of the teleost fish Catostomus commersoni (white sucker): molecular analysis predicts distinct precursors for two CRFs and one urotensin I peptide.

Molecular cloning experiments indicate the presence of two distinct CRF genes in the sucker genome encoding independent 162-amino-acid precursors, which both consist of a signal sequence, succeeded by a cryptic peptide and subsequently by the hormone moiety. The two 41-amino-acid CRF peptides differ by an Ala-->Val substitution at amino acid position 28. CRF transcripts are primarily found in the sucker pre-optic nucleus (PON), to a much lesser extent in the lateral tuberal nucleus (LTN). In contrast, urotensin I (U I) encoding mRNA is equally present in both tissues. In urophysectomized fish, U I mRNA is elevated especially in LTN tissue, while CRF mRNA levels remain more or less constant in the PON and LTN regions.

Amino Acid Sequence↗
PubMed1990

Vasotocin genes of the teleost fish Catostomus commersoni: gene structure, exon-intron boundary, and hormone precursor organization.

cDNA clones encoding two members of the vasotocin hormone precursor gene family have been isolated from the white sucker Catostomus commersoni. The hormone is encoded by at least two distinct genes, both of which are expressed, as indicated by Northern blot analysis. Genomic DNA amplified by the polymerase chain reaction has been used to define exon-intron boundaries. Both vasotocin genes contain introns in positions corresponding to those found in the gene of their mammalian counterpart vasopressin. The predicted vasotocin precursors show a surprising degree of sequence divergence, amounting to 45% at the amino acid level, of which only approximately half can be accounted for by conservative amino acid changes. The precursors include a hormone moiety followed by a putative neurophysin sequence that is longer at the C-terminus by a tract of some 30 amino acids by comparison to their mammalian counterpart. Each of these sequences contains a leucine-rich core segment resembling that found in copeptin, a glycopeptide moiety present in mammalian vasopressin precursors.

Amino Acid Sequence↗
PubMed1990

Molecular cloning of two distinct vasotocin precursor cDNAs from chum salmon (Oncorhynchus keta) suggests an ancient gene duplication.

The structures of two different vasotocin precursors from chum salmon brain have been elucidated through the molecular cloning of their corresponding cDNAs. Although the predicted precursors, consisting respectively of 153 and 158 amino acids, have the same structural organisation, they show 35% amino acid sequence divergence, of which only approximately half are isofunctional substitutions. Remarkably, while the C terminal segments of both precursors resemble the glycopeptide moiety of the related mammalian vasopressin precursor, both salmon precursors lack consensus sequences for N-glycosylation.

Amino Acids↗
PubMed1989

Two isotocin genes are present in the white sucker Catostomus commersoni both lacking introns in their protein coding regions.

Two genes each encoding a distinct precursor protein to the hormone isotocin and a neurophysin-related protein are present in the teleost fish Catostomus commersoni. These precursors are referred to as isotocin 1 and 2. As shown by the polymerase chain reaction technique, both genes lack introns in their protein-coding sequences. Both genes are transcribed giving rise to mRNAs of 920 (isotocin 1) and 1020 (isotocin 2) bases, respectively. Based on the nucleotide sequences, the predicted isotocin precursors contain, besides the hormone moiety, a neurophysin-like protein that, in contrast to its mammalian counterpart, is extended at its C-terminus by a peptide which includes a leucine-rich core segment. This segment shows similarities to the copeptin of the mammalian vasopressin precursor that is known to possess prolactin-releasing activity. The data imply that the mammalian copeptin sequence was initially part of a larger ancestral neurophysin molecule.

Amino Acid Sequence↗
PubMed1989

Vasotocin and isotocin precursors from the white sucker, Catostomus commersoni: cloning and sequence analysis of the cDNAs.

The nucleotide sequences of cloned cDNAs encoding the precursors for vasotocin and isotocin have been elucidated by analyzing a lambda gt11 library constructed from poly(A)+ RNA from the hypothalamic region of the teleost fish Catostomus commersoni. Screening of the library was carried out with synthetic oligonucleotide probes deduced from the amino acid sequences of the nonapeptides vasotocin and isotocin. The cDNA nucleotide sequences predict isotocin and vasotocin prohormone precursors each consisting of a signal peptide, a hormone moiety, and a neurophysin-like molecule. However, in comparison to their mammalian counterparts, both fish neurophysins are extended at their C termini by an approximately 30 amino acid sequence with a leucine-rich core segment. These extensions show striking similarities with the glycopeptide moiety (the so-called copeptin) present in mammalian vasopressin precursors, except that they lack the consensus sequence for N-glycosylation. These data suggest that mammalian copeptin is derived from the C terminus of an ancestral neurophysin.

Amino Acid Sequence↗
PubMed1988

Expression and electrophysiological identification of the receptor for bombesin and gastrin-releasing peptide in Xenopus laevis oocytes injected with polyA+ RNA from rat brain.

The receptor for bombesin and the related peptide, gastrin-releasing peptide (GRP) has been induced in frog oocytes by injection of polyA+ RNA from rat brain. The primed oocytes responded to peptides of the bombesin family (GRP, neuromedin C of bombesin) by showing dose-dependent oscillations in membrane currents as recorded by the voltage-clamp method. The induced membrane changes were suppressed when oocytes were pretreated with a bombesin-receptor antagonist.

Animals↗
PubMed1988

Cloning and sequence analysis of cDNA for corticotropin-releasing factor precursor from the teleost fish Catostomus commersoni.

The sequence of a cDNA encoding the corticotropin-releasing factor precursor has been identified by screening lambda gt11 libraries constructed from poly(A)+ RNA of the hypothalamic region of the white sucker Catostomus commersoni brain with synthetic oligonucleotide probes deduced from the sequence of the rat corticotropin-releasing factor. The amino acid sequence of corticotropin-releasing factor of the sucker is strikingly conserved when compared to its counterpart from rat and differs only in two positions at the carboxyl terminus; in contrast, there is little similarity between their cryptic regions.

Amino Acid Sequence↗
PubMed1988

Functional expression of the oxytocin receptor in Xenopus laevis oocytes primed with mRNA from bovine endometrium.

Synthesis of the uterine receptor for the hypothalamic hormone oxytocin has been induced in oocytes from Xenopus laevis previously primed with bovine endometrium mRNA. The injected oocytes responded to oxytocin by showing dose-dependent oscillations in membrane currents as recorded by the voltage-clamp method. The response was specific in that it was not elicited by several other peptides tested. The oxytocin-induced membrane changes were suppressed when oocytes were pretreated with an oxytocin receptor antagonist.

Animals↗
PubMed1987

Vasopressin gene transcripts in the bovine corpus luteum are defective.

cDNA clones corresponding to vasopressin gene transcripts were isolated from a lambda gt11 library made using mRNA extracted from a bovine corpus luteum of the early non-pregnant cycle. None of the characterized clones included the vasopressin-encoding exon A sequence, instead two of these clones included sequence from the first intron. Together these data and controls indicate that vasopressin gene transcription in this tissue does not yield translatable mRNA and that positive RNA-DNA hybridization signals are not necessarily evidence for local biosynthesis of the neuropeptide.

Animals↗
PubMedDate not supplied

Adrenal-specific transgene expression and derivation of conditionally immortal rat adrenocortical cell lines.

Conditional immortalisation of cells is a powerful tool for establishing in vitro models maintaining a differentiated phenotype. We are utilising this approach to derive cell lines that maintain the characteristics of glomerulosa and fasciculata cells of the adrenal cortex. Such cell lines should provide a system in which to study aspects of adrenocortical function that are relevant to hypertension, such as the effects of the renin-angiotensin system on steroidogenesis.

Adrenal Cortex↗
PubMedDate not supplied

StAR protein is expressed in both medulla and cortex of the bovine and rat adrenal gland.

We have employed polyclonal antibodies to a peptide sequence of bovine steroidogenic acute regulatory (StAR) protein and human placental 3beta-hydroxysteroid dehydrogenase (3beta-HSD) to determine the localisation and distribution of these proteins in rat and bovine adrenal glands. Immunohistochemical staining demonstrated the presence of StAR protein in the zona glomerulosa (ZG), zona fasciculata (ZF), zona reticularis (ZR) and in the medulla of both species. For 3beta-HSD, immunostaining was observed in the ZG, ZF and ZR of the rat adrenal and was absent in the medulla. Immunoblotting experiments showed intense bands for StAR protein (30 kDa, 37 kDa) in the mitochondria of bovine ZG, ZF and medulla and a less intense band (30 kDa) in the microsomes. In rat ZG and ZF/R mitochondria only the 30 kDa protein was present. For 3beta-HSD, an intense band (42 kDa) was found in microsomes and mitochondria of rat and bovine ZG and ZFR. A very faint signal for 3beta-HSD was seen in adrenal medulla. In conclusion, StAR (or a closely related) protein is present throughout the adrenal gland in rat and bovine species in contrast to 3beta-HSD which is confined to the steroidogenic zones. The possible function of StAR protein in the adrenal medulla merits investigation.

3-Hydroxysteroid Dehydrogenases↗
PubMedDate not supplied

The expression of steroidogenic acute regulatory protein (StAR) in bovine adrenocortical cells.

StAR protein may facilitate rapid transfer of cholesterol from the outer to the inner mitochondrial membrane, the site at which cholesterol is converted to pregnenolone by the cholesterol side chain cleavage complex. We have studied the effect of ACTH treatment on StAR mRNA and protein levels in bovine adrenocortical cells in primary culture. Cells were initially cultured for 3 days after isolation, and then treated with ACTH (10(-8) M) for various times up to 24 hours. Northern analysis of total BAC mRNA, using a [alpha32P]-labelled cDNA probe encoding a 5' region of bovine StAR mRNA, revealed two principal hybridising species of 1.6 and 3.0 kb. Western immunoblot analysis revealed a principal band at 30 kDa. Levels of both StAR mRNA and protein showed an increase at 1 hour, reached a maximum at around 6 hours and declined to basal levels at 24 hours. Cortisol secretion (measured by RIA) showed a similar change over the same period. From these results it appears that StAR mRNA and protein levels in BAC are acutely regulated in concert with ACTH-stimulated cortisol secretion.

Adrenal Cortex↗