A protease inhibitor of the serpin family is a major protein in carp perimeningeal fluid: I. Protein purification and characterization

Two isoforms of a protease inhibitor of the serpin family (p62) have been purified from bighead carp perimeningeal fluid. Both isoforms migrate with an apparent molecular mass of 62 kDa on reducing and nonreducing sodium dodecyl sulfate-polyacrylamide gels. Both proteins inhibited the activities of bovine trypsin, bovine chymotrypsin, and porcine pancreatic elastase. They also formed complexes with these proteases that were resistant to sodium dodecyl sulfate treatment. p62 exists in the extracts of all tissues examined, including brain, head kidney, kidney, liver, muscle, ovary, pituitary, and spleen. It is also present in serum, ovarian fluid, and milt as well as perimeningeal fluid. The protease inhibitor is a glycoprotein, and its carbohydrate moiety could be removed by endoglycosidase F. Because p62 resembles mammalian alpha 1-antitrypsin in many aspects, it is likely a fish equivalent of alpha 1-antitrypsin.

A protease inhibitor of the serpin family is a major protein in carp perimeningeal fluid: II. cDNA cloning, sequence analysis, and Escherichia coli expression

A cDNA clone, pCP9, has been isolated from a common carp liver cDNA library by immunoscreening with polyclonal antiserum raised against purified bighead carp alpha 1-antitrypsin. This clone is 1,396 bp in length and has an open reading frame encoding a protein of 410 amino acid residues. The deduced amino acid sequence shows moderate homology to human alpha 1-antitrypsin (38%), guinea pig contrapsin (35%), human alpha 1-antichymotrypsin (34%), and human proteinase C inhibitor (31%), all members of the serine protease inhibitor (serpin) family. To confirm further that the cDNA clone was derived from the authentic carp alpha 1-antitrypsin gene, the presumptive mature protein of pCP9 was expressed in Escherichia coli. The molecular mass of the recombinant protein matched that predicted from the nucleotide sequence. This recombinant protein, which was recognized by antiserum against native alpha 1-antitrypsin, was capable of formation of serpin-enzyme complexes with trypsin, chymotrypsin, and elastase. Therefore, we conclude that the protein encoded by the pCP9 clone is indeed carp alpha 1-antitrypsin. Expression of alpha 1-antitrypsin in brain was confirmed by reverse transcription and polymerase chain reaction performed on mRNA derived from both common carp and bighead carp brain.

Differential responses of protein kinase C substrates (MARCKS, neuromodulin, and neurogranin) phosphorylation to calmodulin and S100

Phosphorylation of three physiological substrates of protein kinase C (PKC), MARCKS, neuromodulin (Nm), and neurogranin (Ng), was analyzed to determine their relative efficacy as substrates of PKC alpha, beta, and gamma and sensitivities to inhibition by calmodulin (CaM) and S100. Comparison of the Vmax/Km of the phosphorylation of each individual substrate indicated the order of efficacy as PKC substrate was MARCKS > Nm > Ng. Phosphorylation of these proteins in a mixture by PKC beta and gamma was indistinguishable from that when each individual substrate was phosphorylated by these two isozymes. In contrast, the rates of PKC alpha-catalyzed phosphorylation of Nm and Ng in a mixture also containing MARCKS were significantly reduced as compared to that when Nm or Ng was individually phosphorylated by this isozyme. When these substrates were present in a mixture, both CaM and S100 inhibited the PKC-catalyzed phosphorylation of MARCKS to a higher degree than that of Nm or Ng. Protease-activated catalytic fragment of PKC (PKM) was used to determine the effects of Ca2+ and phospholipid on the CaM and S100-mediated inhibition of PKC substrate phosphorylation. CaM and S100 inhibited the PKM-catalyzed phosphorylation of MARCKS only in the presence of Ca2+ and addition of phosphatidylserine (PS)/dioleoylglycerol (DG) did not influence the inhibitory effect. Phosphorylation of Nm or Ng by PKM was inhibited by CaM to a higher degree in the absence than in the presence of Ca2+. S100 was ineffective in inhibiting the phosphorylation of Nm and Ng without Ca2+ and only poorly effective in the presence of Ca2+. The CaM-mediated inhibition of Nm or Ng phosphorylation by PKM was also not affected by PS/DG either with or without Ca2+. The results presented here demonstrate that MARCKS is a preferred substrate of PKC and its phosphorylation by PKC is most sensitive to inhibition by regulatory proteins such as CaM and S100.

Potentiation by endogenously released ATP of spontaneous transmitter secretion at developing neuromuscular synapses in Xenopus cell cultures

1. Previously we have shown that extracellular application of ATP, a substance co-stored and co-released with acetylcholine (ACh) in the peripheral nervous system, markedly potentiated the frequency of spontaneous synaptic currents (SSCs) produced by ACh. In the present study, we have further characterized the purinoceptor which mediates the potentiation effect of ATP and the role of endogenously released ATP. 2. Pretreatment with a P2-purinoceptor antagonist, suramin (0.3 mM), but not a P1-purinoceptor antagonist, 8-phenyltheophylline (0.1 mM), prevented the potentiating effect of ATP. 3. We studied the role of endogenously released ATP by examining the effect of a specific P2-purinoceptor antagonist on the frequency of spontaneous synaptic events at high-activity synapses (> or = 3 Hz) and found that suramin, but not 8-phenyltheophylline markedly reduced the frequency of SSCs at these high-activity synapses. In addition, desensitizing the P2-purinoceptor with alpha,beta-methylene ATP also produced similar effects to suramin. 4. Extracellular application of the L-type Ca2+ channel blockers, verapamil, nifedipine or diltiazem (10 microM each) reduced SSC frequency of high-activity synapses, while the N-type Ca2+ channel blocker, omega-conotoxin had no appreciable effect. The potentiating effect of ATP was further prevented by pretreatment with the L-type Ca2+ channel blockers. On the other hand, Bay K 8644, which is a depolarization-dependent L-type Ca2+ channel agonist, potentiated SSC frequency at these high-activity synapses. 5. These results suggest that endogenous release of ATP at developing neuromuscular synapses is responsible for the maintenance of high levels of spontaneous ACh release, which is known to play a crucial role in regulating postsynaptic differentiation.

Peripheral deafferentation alters calcitonin gene-related peptide mRNA expression in visceral sensory neurons of the nodose and petrosal ganglia

Visceral sensory neurons of the glossopharyngeal and vagus nerves are located in the petrosal and nodose ganglia, respectively. Our previous studies showed that peripheral axotomy which removes afferent input to visceral sensory perikarya decreased the number of calcitonin gene-related peptide (CGRP)-immunoreactive (ir) neurons in the petrosal but not the nodose ganglion. To evaluate axotomy-induced changes in CGRP mRNA expression, we used in situ hybridization histochemistry with 35S-labeled oligonucleotide probes. CGRP mRNA-containing neurons were studied 1, 3, 7 and 14 days after peripheral deafferentation of the left nodose and petrosal ganglia via transection of the left cervical vagus, superior laryngeal, glossopharyngeal and carotid sinus nerves. The numbers of CGRP mRNA-containing neurons in the deafferented petrosal ganglion were significantly reduced at 3, 7 and 14 days compared to either intact or sham-operated control ganglia. However, the density of hybridization product in the positively-labeled petrosal ganglion cells was not significantly changed. The numbers of CGRP mRNA-containing neurons in the deafferented nodose ganglion were significantly reduced at 3 and 7 days. These data suggest that axotomy-induced changes in CGRP-ir neurons of the petrosal ganglion correlate with changes in CGRP mRNA and probably result from altered CGRP gene expression. In addition, in situ hybridization histochemistry revealed changes in CGRP neurons of the nodose ganglion which were not apparent with immunocytochemistry.

The complete nucleotide sequence and gene organization of carp (Cyprinus carpio) mitochondrial genome

The complete sequence of the carp mitochondrial genome of 16,575 base pairs has been determined. The carp mitochondrial genome encodes the same set of genes (13 proteins, 2 rRNAs, and 22 tRNAs) as do other vertebrate mitochondrial DNAs. Comparison of this teleostean mitochondrial genome with those of other vertebrates reveals a similar gene order and compact genomic organization. The codon usage of proteins of carp mitochondrial genome is similar to that of other vertebrates. The phylogenetic relationship for mitochondrial protein genes is more apparent than that for the mitochondrial tRNA and rRNA genes.

Molecular cloning and sequencing of a carp cDNA encoding mitogen-activated protein kinase kinase

We have cloned a full-length cDNA encoding the mitogen-activated protein kinase kinase (MKK) from a carp liver cDNA library. The cDNA contains 1970 bp with a single open reading frame encoding a 397 amino acid protein. By comparing with known MKK sequences from other species, carp MKK is 78%, 80%, 76% and 58% identical to rat MKK1, rat MKK2, Xenopus MKK and Drosophila MKK.

L-type Ca2+ channel is involved in the regulation of spontaneous transmitter release at developing neuromuscular synapses

Involvement of an L-type Ca2+ channel in the regulation of spontaneous transmitter release was studied in Xenopus nerve-muscle cultures. The frequency of spontaneous synaptic currents, which reflects impulse-independent acetylcholine release from the nerve terminals, showed a marked increase in high-K+ medium or after treatment with a phorbol ester, 12-O-tetradecanoyl-phorbol 13-acetate, a drug that activates protein kinase C and depolarizes the presynaptic neuron. The potentiation effect of high K+ and 12-O-tetradecanoyl-phorbol 13-acetate requires Ca2+ influx through the L-type Ca2+ channel in the plasma membrane, since it was significantly reduced by the presence of nifedipine, verapamil or diltiazem and enhanced by Bay K 8644, an L-type Ca2+ channel agonist. It was shown recently that adenosine 5'-triphosphate markedly potentiates the spontaneous acetylcholine release at these synapses through the binding of P2-purinoceptors and the activation of protein kinase C. We found in the present study that potentiation effects of adenosine 5'-triphosphate are inhibited by L-type Ca2+ channel blockers, suggesting that the L-type Ca2+ channel is responsible for the positive regulation of spontaneous acetylcholine secretion by adenosine 5'-triphosphate at the developing neuromuscular synapses. Our data suggest that modulation of the L-type Ca2+ channel in embryonic motor nerve terminals is important for the regulation of spontaneous transmitter release.

Tailored syringes as "bridging skeleton" in delayed sternal closure of complex congenital heart operation

We propose a new technique using trimmed plastic syringes as a "bridging skeleton" in delayed sternal closure for complex congenital heart surgery. The technique achieves at low cost good stability and the necessary compliance vital for ultimate survival.

Characterization of a 7.5-kDa protein kinase C substrate (RC3 protein, neurogranin) from rat brain

A 7.5-kDa heat- and acid-stable rat brain protein kinase C (PKC) substrate was purified to near homogeneity by a two-step procedure using DEAE-cellulose and hydroxylapatite column chromatography. This 78-amino-acid protein has a sequence identical to that deduced from rat brain RC3 cDNA identified with a cortex-minus-cerebellum subtracted cDNA probe (J. B. Watson et al., J. Neurosci. Res. 26, 397-408, 1990) and exhibits extensive sequence identity to bovine brain neurogranin (J. Baudier et al., J. Biol. Chem. 266, 229-237, 1991). On sodium dodecyl sulfate-polyacrylamide gel electrophoresis this protein, RC3, migrated as a M(r) 15-18K species in the presence of reducing agent and as heterogeneous species of M(r) 13-28K in the absence of reducing agent. Phosphorylation of RC3 by PKC alpha, beta, or gamma was stimulated by Ca2+, phospholipid, and diacylglycerol. A single site, Ser36, which is adjacent to the predicted calmodulin (CaM)-binding domain, was phosphorylated by these enzymes. Phosphorylation of RC3 by PKC or PKM, a protease-degraded PKC, was inhibited by CaM. The effect of CaM apparently targets at RC3, as phosphorylation of protamine sulfate by PKM was not inhibited by CaM. In the absence of Ca2+, RC3 formed a stoichiometric complex with CaM as evidenced by an increase in the M(r) determined by gel filtration chromatography. In the presence of Ca2+, the affinity of RC3 toward CaM is greatly reduced and Ca2+/CaM becomes less inhibitory of the PKM-catalyzed phosphorylation of RC3. Phosphorylation of RC3 by PKM prevented the interaction of this protein with CaM even in the absence of Ca2+. A 20-amino-acid synthetic peptide (AS-20F-W) containing the PKC phosphorylation site and CaM-binding domain of RC3 (Ala29-Ser48) with a substitution of Phe37 with tryptophan was used to monitor the interaction of this peptide with CaM by spectrofluorometry. In the absence of Ca2+, CaM caused negligible change in tryptophan fluorescence of the peptide; however, an enhancement and blue-shift of the emission fluorescence was observed in the presence of Ca2+. It seems that this synthetic peptide, as well as RC3 holoprotein, interacts with CaM through electrostatic interaction in the absence of Ca2+ but through hydrophobic interaction in the presence of Ca2+. In rat brain homogenate, RC3 formed a stable complex with CaM in the presence of Ca2+, as demonstrated by immunoblot analysis following gel filtration chromatography.(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular cloning and relationship of highly repetitive Hind III sequences in three cyprinid species: silver carp, bighead carp and grass carp

The genomes of three cyprinid species, silver carp, bighead carp and grass carp, all contain highly repetitive Hind III sequences. There are two types of repeated sequences found in the genome of bighead carp but only one type of repeated sequence found in the genomes of silver carp and grass carp. Their lengths are from 186 to 201 bp. These sequences are arranged tandemly in the genomes. Their copy numbers are about 3.65 x 10(5) per haploid genome and total contents are about 5% of the genomes. The Hind III repetitive sequences of silver carp, bighead carp and grass carp are very similar to one another but completely different from those known repetitive DNAs of common carp, tilapia, pollock and salmon.

How is protein kinase C activated in CNS

Protein kinase C (PKC) enzyme family consists of the Ca(2+)-dependent and -independent subgroups of phospholipid/diacylglycerol (DAG)-stimulated serine/threonine protein kinases. These enzymes exhibit distinct cellular and subcellular localizations in CNS and subtle differences in their biochemical characteristics and substrate specificities. It is believed that each of these isoenzymes respond differently to different input signals. However, detailed mechanism for the functioning of these enzymes in vivo is largely unknown; this is in part due to the absence of specific activator, inhibitor, or substrate for each of these enzymes. Recent advances in biochemical, biophysical, and molecular characterizations have defined certain structural features important to confer the stimulatory responses of these enzymes to Ca2+, DAG or phorbol ester, and Zn2+; other features important for the binding of anionic phospholipids, Ca2+/phospholipid complexes, and cis-unsaturated fatty acids have not yet been characterized. Activation of PKC requires the increase in [Ca2+]i and DAG and/or cis-unsaturated fatty acids. Ca2+ promotes the interactions of the Ca(2+)-dependent subgroup of PKCs with membrane phosphatidylserine (PS) and the enzymes become partially active when simultaneously associated with phosphatidylinositol 4,5-bisphosphate or fully active when DAG is available. Free fatty acids such as arachidonic acid, generated by the activation of phospholipase A2, could synergize with DAG to activate the enzyme maximally. The Ca(2+)-independent subgroup of PKCs also become active when associated with PS at elevated level of DAG. Sustained activation of PKCs leads to the conversion of these enzymes into membrane-inserted and membrane protein-associated forms, which may be responsible for certain long-term neural responses. Activation of PKC results in the phosphorylation of cellular proteins; among them, several calmodulin (CaM)-binding proteins are the prominent substrates of these kinases. Phosphorylation of these proteins by PKC favors the release of CaM, which is required for the Ca2+/CaM-dependent enzymes. Thus, activation of PKCs can lead to diverse cellular responses through such amplification steps. Future studies should be directed at the elucidation of the activation of each PKC isoform in vivo to correlate with the physiological responses.

C-type natriuretic peptide mediates the hypothalamic actions of the natriuretic peptides to inhibit luteinizing hormone secretion

Both A- and C-type natriuretic peptides (ANP and CNP, respectively) significantly reduce LH secretion when injected into the third cerebral ventricle of conscious rats. To establish which natriuretic peptide receptor subtype transduces these inhibitory messages, we have employed novel cytotoxin cell targeting techniques to selectively destroy cells in the hypothalamus that respond to ANP or CNP. Rats pretreated with ANP conjugated to the toxic A-chain of the plant cytotoxin ricin failed 1 week later to respond to central injection of ANP with the normal inhibition of LH secretion. These rats did, however, respond with significant inhibition of LH secretion to central injection of CNP. In fact, the LH inhibition observed after CNP injection was significantly greater than that expressed after similar injection of CNP in rats pretreated with unconjugated ricin A-chain (toxin control). Those control rats displayed significant reduction of LH levels in response to ANP injection as well. Plasma LH levels were not significantly affected by central administration of either ANP or CNP in rats pretreated with ricin A-chain conjugated to CNP. These results further demonstrate the power of this novel technology and provide positive evidence supporting our hypothesis that ANP exerts its LH-inhibiting effect by displacing endogenous CNP from clearance receptors within the brain. This endogenous CNP, then, like exogenously applied CNP, activates the guanyl cyclase-B receptors on cells, which are part of the network controlling the release of LHRH.

Protein kinase C phosphorylates Ser152, Ser156 and Ser163 but not Ser160 of MARCKS in rat brain

MARCKS is one of the major physiological substrates of PKC and was reported to be phosphorylated by PKC at 4 serine residues that are within the CaM-binding region (Graff et al., J. Biol. Chem. 264, 11912, 1989). Using MARCKS from rat brain and a synthetic peptide of 25 amino acids containing all 4 of the serine residues, we investigate the differences in phosphorylation by PKC isozymes I, II and III. Tryptic peptide analysis of PKC phosphorylated MARCKS or peptide, we found 32P was in peptides of (K)S152FK, (R)FS156FK and LS160GFS163FK. Further digestion of LSGFSFK with alpha-chymotrypsin revealed that 32P incorporation occurred only at Ser163 but not at Ser160. The initial rates and stoichiomatry of phosphorylation of Ser152 and Ser156 were twice as those of Ser163 using either one of the three PKC isozymes. These results indicate that in vitro, PKC phosphorylates MARCKS only at three sites, but not at Ser160 as that reported previously, and there was no preferential phosphorylation of MARCKS by either PKC isozyme I, II or III.

C-type natriuretic Peptide stimulates prolactin secretion by a hypothalamic site of action

The most recently discovered member of the family of natriuretic peptides, C-type natriuretic peptide (CNP), exerts many pharmacologic actions similar to its structural homolog A-type natriuretic peptide (ANP). Like ANP it failed to significantly alter prolactin release from dispersed, rat anterior pituitary cells incubated under static or dynamic conditions. Unlike ANP, however, which inhibits prolactin secretion in vivo by a hypothalamic action, CNP injection into the third cerebroventricle significantly stimulated prolactin secretion in ovariectomized, conscious rats. The effect was highly significant 15 min after injection and transient, lasting 30 min in animals injected with 2 nmole CNP. In a companion group of rats, significant inhibition of plasma prolactin levels was observed after central administration of similar doses of ANP. These results suggest differing hypothalamic actions of the CNP and ANP perhaps mediated by multiple natriuretic peptide receptors present in the tissue. Further, they provide additional support for unique roles exerted within the central nervous system by these structural homologs.

The primary structures of growth hormones of three cyprinid species: bighead carp, silver carp, and grass carp

The primary structures of growth hormone (GH) of three cyprinid species, bighead carp, silver carp, and grass carp, were determined by a chemical method and/or by molecular cloning. The bighead carp GH was extracted from pituitary tissue by use of an alkaline medium, then successively purified by gel filtration, hydrophobic interaction column chromatography, and reverse-phase high-pressure liquid chromatography. The primary structure of bighead carp GH determined chemically is identical to that deduced from the cDNA nucleotide sequence. By molecular cloning, the primary structures of silver carp and grass carp GHs were also determined. The GHs of these three cyprinid species all contain 188 amino acid residues and their sequences are identical. When four of the five cysteines of cyprinid GHs were arranged to match the same positions of cysteines of other vertebrate GHs, a maximally matched alignment was achieved. Among fishes, GHs are relatively conserved within the same order (82 to 100% identity) but they are more diversified between orders (49 to 68% identity). In further comparison, fish GHs are even more different from tetrapod GHs (37 to 58% identity). Although the primary structures of vertebrate GHs are relatively variable, four homologous sequences, notably one located at the C-terminal, are found.

Molecular cloning of silver carp and bighead carp prolactin

The cDNAs encoding the prolactin of silver carp (scPRL) and bighead carp (bcPRL) have been cloned. Deduced from the nucleotide sequences, both scPRL and bcPRL are composed of 187 amino acid residues. Only one residue is different between scPRL and bcPRL. Homology analysis indicates that scPRL and bcPRL are highly homologous to carp PRL (97%), relatively conserved in relation to PRLs of salmon, trout, and tilapia (64-69%), and diversified from avian and mammalian PRL (30-35%). Similar to PRLs of other species of fish, scPRL and bcPRL lack the first 12 N-terminal residues of avian and mammalian PRLs.

Hypothalamic effects of C-type natriuretic Peptide on luteinizing hormone secretion

Previous studies have demonstrated hypothalamic sites of action of A-type natriuretic peptide (ANP) in the inhibition of luteinizing hormone (LH) secretion, acting at least in part, via an opiatergic mechanism. C-type natriuretic peptide (CNP) was identified recently and is thought to be the predominant brain form of the family of natriuretic peptides. Third cerebroventricular injection of CNP in doses of either 0.1, 1.0 or 2.0 nmole significantly inhibited, in a dose-related fashion, plasma LH levels when compared to levels present in saline-injected controls. When compared to the LH-inhibiting action of ANP, CNP appeared more potent (effective at lower doses) and efficacious (longer duration of action for the maximum effective doses). The LH-inhibiting effect of CNP was blocked by prior treatment with the δ-opioid receptor antagonist naltrindole (50 μg), suggesting an enkephalinergic mechanism of action. CNP in log doses ranging from 0.01 to 1,000 nM did not significantly alter LH release from dispersed pituitary cells harvested from random cycle female rats, either under static or dynamic (perifusion) incubation conditions. These results indicate that CNP, like ANP, acts at the hypothalamic level to alter LH secretion and suggest that CNP may be the preferential neuroactive members of this family of peptides.

Central peptidergic mechanisms controlling reproductive hormone secretion: novel methodology reveals a role for the natriuretic peptides

A variety of neural factors can influence reproductive hormone secretion by neuromodulatory actions within the hypothalamus or neuroendocrine actions within the anterior pituitary gland. Passive immunoneutralization and antagonist administration protocols have suggested physiological roles for a number of these factors; however, both experimental approaches have severe technical limitations. We have developed novel methodology utilizing cytotoxin cell targeting with neuropeptides linked to the toxic A chain of the plant cytotoxin ricin. With this methodology we can target and destroy in vivo or in vitro cells bearing receptors for that peptide. Ricin A chain conjugated to atrial natriuretic peptide (ANP), a neuropeptide known to pharmacologically inhibit luteinizing hormone-releasing hormone (LHRH) release, was injected into the cerebroventricular system of intact, cycling rats and ovariectomized rats. Cytotoxin conjugate treatment significantly lengthened the estrous cycle. In ovariectomized rats the luteinizing hormone surge induced by steroid priming was completely inhibited. LHRH content of the median eminences of these rats was not significantly altered. These data suggest that ANP binding to clearance receptors in the hypothalamus displaces the C-type natriuretic peptide (CNP) from the shared clearance receptor, making more CNP available to inhibit LHRH release. In the absence of cells bearing the clearance receptor all available CNP binds to the ANPR-B receptor and exerts its effect via an inhibitory interneuron, since LHRH fibers are spared by this treatment.

A prolactin release inhibiting activity isolated from neurointermediate lobe extracts is an endothelin-like peptide

A prolactin release-inhibiting factor has been reported in extracts of rat and bovine neurointermediate lobes of the pituitary gland. This material when isolated by Sephadex G-25 chromatography or by C-8 high pressure liquid chromatography coelutes with synthetic forms of all members of the mammalian endothelin family of peptides and with their immediate precursors, big-ET-1 and big-ET-3. The endogenous material crossreacts in an endothelin radioimmunoassay. Immunohistochemical analysis of endothelin-like immunoreactivity in the neurointermediate lobe revealed a predominantly intermediate lobe localization. Individual immunopositive cells were visualized in the intermediate lobe. Preabsorption of chromatographically isolated prolactin release-inhibiting activity with an endothelin antiserum which recognizes all members of the ET family of peptides abolishes its in vitro bioactivity. These results suggest that a prolactin release-inhibiting activity present in the neurointermediate lobe is endothelin or an endothelin-like peptide.

Isolation and sequence analysis of carp gonadotropin beta-subunit gene

Using the cDNA encoding the beta subunit of carp gonadotropin (cGTH-beta) as a probe, 14 clones containing cGTH-beta gene have been isolated from a carp genomic library. Nucleotide sequence analysis indicated that the transcriptional unit of the cGTH-beta gene is 1.2 Kb. Similar to mammalian GTH-beta genes, cGTH-beta gene contains three exons and two introns. The locations of the exon/intron junctions also correspond to those of mammalian GTH-beta gene. Using the primer extension assay, the start site of transcription was determined to be 35 or 37 bp upstream from the translation initiation codon. The TATAA box is present in the 5' flanking region of the gene, 21 bp upstream from the start site of transcription. Three polyadenylation signals, AATAAA, are located in the 3' noncoding region, 111, 430, and 442 bp downstream from the stop codon of translation, respectively.

The occurrence of three isoenzymes of protein kinase C (alpha, beta and gamma) in retinas of different species

The localisation and immunochemical identification of 3 different forms of protein kinase C (PKC-alpha, PKC-beta and PKC-gamma) in retinas of different species were analysed by immunohistochemistry and SDS-PAGE-Western blotting, respectively. Only in some cases was there a correlation between the findings from each procedure. One reason for the lack of correlation could be the small amounts of PKC present in some retinas, which made detection possible only by first concentrating the antigen by SDS-PAGE and then carrying out Western blotting. Another possible reason is that an antibody recognises unknown antigens immunohistochemically, but, because of their specific characteristics, they are denatured when subjected to SDS-PAGE and Western blotting and therefore remain undetected. PKC-beta immunoreactivity is present in rabbit, frog and goldfish retinas but absent from the rat retina. However, SDS-PAGE and Western blotting experiments showed that the PKC-beta isoenzyme is absent from the fish retina but present in the rat retina. PKC-beta immunoreactivity in rabbit retina is present in ganglion and/or amacrine cells; in the frog retina the enzyme is associated with some bipolar cells. In the goldfish retina, PKC-beta is associated with a large population of cells in the ganglion cell layer as well as with some amacrine cell bodies. PKC-alpha is present primarily in bipolar cells of rat, fish and rabbit retinas and was not detected by immunohistochemistry or blotting experiments in the frog retina. SDS-PAGE and Western blotting of retinal extracts from different species showed that PKC-gamma occurs in the rabbit where it was associated with ganglion and/or amacrine cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Organization and nucleotide sequence of carp gonadotropin α subunit genes

We have used PCR to amplify and align the sequence of two genes encoding cGTH alpha. Both genes comprise four exons and three introns. The organization of cGTH alpha genes is very similar to that of mammalian GTH alpha genes. However, the cGTH alpha genes only span a region of 1.2 kb which is much smaller than those mammalian GTH alpha genes.

CNP-22 stimulates, rather than inhibits, water drinking in the rat: evidence for a unique biological action of the C-type natriuretic peptides

C-type natriuretic peptide (CNP) shares structural homology with A-type natriuretic peptide (ANP). Unlike ANP, which inhibits experimentally induced water drinking, CNP stimulates intake under similar conditions. The action of CNP to stimulate water drinking is not due to competition with ANP for the clearance receptor which recognizes both peptides since the ligand specific for that binding site, C-ANF 4-23, like ANP, inhibits water drinking under the same conditions.