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At least 19 recordsLinked to original sources
PubMed1993

Distribution and activity of dogfish NPY and peptide YY in the cardiovascular system of the common dogfish.

Neuropeptide Y is present in sympathetic nerves in the mammalian cardiovascular system. This study has investigated the distribution of neuropeptide Y in the cardiovascular and gastrointestinal systems and the effect of dogfish neuropeptide Y and related peptides on cardiovascular tissue of an elasmobranch fish, the common dogfish (Scyliorhinus canicula). Neuropeptide Y-like immunoreactivity is present in varicose nerve fibers innervating dogfish gut and cardiovascular tissue and in endocrine cells of the dogfish spiral intestine. Dogfish neuropeptide Y, dogfish peptide YY, and porcine neuropeptide Y contract the dogfish afferent branchial artery in a concentration-dependent manner. The effect is not inhibited by the presence of tetrodotoxin or by removal of the endothelium. The mammalian Y1 receptor selective agonist [Leu31Pro34]NPY but not the mammalian Y2 receptor selective agonist neuropeptide Y-(13-36) peptide has vasoconstrictor properties in this system, suggesting that the receptor mediating the vasoconstriction resembles the mammalian Y1 receptor more than the Y2 receptor.

Absorption↗
PubMed1993

Cardiovascular actions of dogfish urotensin II in the dogfish Scyliorhinus canicula.

Bolus injections of synthetic dogfish urotensin II (0.1-1.0 nmol) into the celiac artery of the conscious dogfish Scyliorhinus canicula (n = 8) resulted in sustained and dose-dependent increases in arterial blood pressure and pulse pressure. A maximum rise in mean arterial pressure of 10.5 +/- 1.2 mmHg (equivalent to 38.6 +/- 4.2% over mean basal values) and a maximum increase in pulse pressure of 3.9 +/- 0.8 mmHg was elicited by injection of 0.5 nmol of peptide. In comparison, a bolus injection of epinephrine (5 nmol) elicited a rise of 24.8 +/- 3.3% in mean arterial pressure. Bolus injection of 0.5 nmol synthetic goby (Gillichthys mirabilis) urotensin II under the same conditions did not elicit a significant hypertensive response. When dogfish urotensin II (0.5 nmol) was administered 3 min after an intra-arterial injection of phentolamine, the rise in arterial blood pressure was completely abolished. Dogfish urotensin II produced a dose-dependent contraction (pD2 = 6.58 +/- 0.07; n = 8) of isolated rings of vascular muscle prepared from the first afferent branchial artery of the dogfish. A maximum contractile force of 1.3 mN was produced by 10(-5) M peptide. The urotensin II-induced contraction of the vascular rings was unaffected by pretreatment with tetrodotoxin (1 microM) or indomethacin (14 microM). It is concluded that urotensin II has potent hypertensive activity in the dogfish that is mediated, at least in part, through release of catecholamines, but the sustained nature of the pressor response suggests that the peptide may have a direct action on the heart.

Animals↗
PubMed1980

Effects of synthetic mammalian gonadotrophin releasing hormone and dogfish hypothalamic extracts on levels of androgens and oestradiol in the circulation of the dogfish (Scyliorhinus canicula L.).

Intravenous injection of synthetic mammalian gonadotrophin releasing hormone (GnRH; 5 microgram per fish) induced a significant increase in androgen levels in the circulation of male dogfish within 4 h. Female dogfish injected with 10 microgram GnRN in November showed significantly raised plasma levels of androgens and oestradiol-17 beta after 90 min as well as an increase in the rat of oviposition. Twice this dose of GnRH failed to produce significant increases in plasma levels of oestradiol in female dogfish in February and the androgen response in these animals was less than that seen after injection of GnRH in November. Injection of an acid extract of dogfish hypothalamus significantly increased plasma levels of androgen and oestradiol in female fish when they were compared with control fish injected with extracts of dogfish cerebellum and the latency of response was similar to that encountered when GnRH was injected. It was concluded that the dogfish hypothalamus contains a factor capable of increasing plasma sex steroid levels in the same species and which is similar in its effects to mammalian GnRH.

Androgens↗
PubMed1998

Cardiovascular actions of dogfish urotensin I in the dogfish, Scyliorhinus canicula.

A synthetic replicate of dogfish urotensin 1 (U-I), a 41-amino-acid residue peptide isolated from an extract of the caudal spinal cord region of the European spotted dogfish Scyliorhinus canicula was prepared in order to study its cardiovascular actions in the species of origin. Bolus intraarterial injections of dogfish U-I (0.3-30 nmol/kg body wt) into the celiac artery of unanesthetized dogfish produced a transient fall in arterial blood pressure (P < 0.05 in the dose range 1-3 nmol/kg) followed by a sustained and dose-dependent rise in pressure (P < 0.05 in the dose range 1-30 nmol/kg). The maximum depressor response (to 3 nmol/kg) was 0.25 +/- 0.08 kPa and the maximum pressor response (to 30 nmol/kg) was 1.08 +/- 0.09 kPa. There was no significant effect on heart rate at any dose tested. Pretreatment of the animals with the alpha-adrenergic receptor antagonist phentolamine significantly (P < 0.05) attenuated the pressor response to injections of dogfish U-I (1 nmol/kg and 10 mol/kg), demonstrating that the effects of the peptide are mediated, at least in part, through release of catecholamines. The data suggest that U-I, released together with potent pressor peptide urotensin II from the caudal neurosecretory system, may play a physiological role in cardiovascular regulation in elasmobranchs.

Amino Acid Sequence↗
PubMed1994

Effects of dogfish urotensin II on lipid mobilization in the fasted dogfish, Scyliorhinus canicula.

Previous studies, both in vitro and in vivo, have shown that urotensin II stimulates hepatic release of nonesterified fatty acids in teleost fish, but the effects of the peptide on lipid mobilization in elasmobranchs are unknown. Infusions of synthetic dogfish urotensin II (40 pmol/min/kg for 30 min followed by 400 pmol/min/kg for 30 min) into the first afferent gill artery of the fasted, unrestrained dogfish, Scyliorhinus canicula (n = 6), produced no significant change in the circulating concentrations of acetoacetate, 3-hydroxybutyrate, and triacylglycerols. Circulating nonesterified fatty acids were undetectable (< 0.1 mmol/liter) both before and after the urotensin II infusions. There was no significant change in the circulating concentrations of glucose and lactate during either the low- or the high-dose infusions. The data support the hypothesis that lipid is converted primarily to ketone bodies in the livers of elasmobranch fish and do not indicate a role for urotensin II in regulating either lipid or glycogen mobilization.

3-Hydroxybutyric Acid↗
PubMed1995

Neural cells from dogfish embryos express the same subtype-specific antigens as mammalian neural cells in vivo and in vitro.

Neural cells are classically identified in vivo and in vitro by a combination of morphological and immunocytochemical criteria. Here, we demonstrate that antibodies used to identify mammalian oligodendrocytes, neurons, and astrocytes recognize these cell types in the developing spiny dogfish central nervous system and in cultures prepared from this tissue. Oligodendrocyte-lineage-specific antibodies O1, O4, and R-mAb labeled cells in the 9 cm dogfish brain stem's medial longitudinal fascicle (MLF) and in areas lateral to it. Process-bearing cells, cultured from the dogfish brain stem, were also labeled with these antibodies. An anti-lamprey neurofilament antibody (LCM), which recognized 60 and 150 kDa proteins in dogfish brain stem homogenates, labeled axons and neurons in the brain stem and axons in the cerebellum of the dogfish embryo. It also labeled cell bodies and/or processes of some cultured cerebellar cells. An anti-bovine glial fibrillary acidic protein antibody, which recognized 42-44 kDa protein(s) in dogfish brain stem homogenates, labeled astrocyte-like processes in the brain stem and cerebellum of the dogfish embryo and numerous large and small flat cells in the cerebellar cultures. These results demonstrate that dogfish oligodendrocytes, neurons, and astrocytes express antigens that are conserved in mammalian neural cells. The ability to culture and identify neural cell types from cartilaginous fish sets the stage for studies to determine if proliferation, migration, and differentiation of these cell types are regulated in a similar fashion to mammalian cells.

Animals↗
PubMed1987

A comparison of dogfish and bovine chymotrypsins.

Bovine and dogfish chymotrypsins were compared to determine if chymotrypsin from a poikilothermic organism (spiny dogfish (Squalus acanthias] adapted to low temperatures possessed catalytic properties different from those of the same enzyme from a warm-blooded animal. An improved procedure was developed for isolating dogfish pancreatic chymotrypsin. The least hydrophobic and smallest substrate used, p-nitrophenyl acetate, had similar enthalpies of association (delta Ha) with both enzymes, whereas larger, more hydrophobic substrates had delta Ha values that were of opposite sign for the two enzymes. As the temperature increased, the association constants (1/Ks) for p-nitrophenyl valerate and p-nitrophenyltrimethyl acetate increased for dogfish chymotrypsin and decreased for bovine chymotrypsin, while the free energies of association (delta Ga) remained relatively constant. Acylation of chymotrypsin was 1.5-2.5 times slower in the dogfish enzyme than in the bovine enzyme except below 15 degrees C with p-nitrophenyltrimethyl acetate. delta H++ for acylation by p-nitrophenyltrimethyl acetate were 2.0 kcal/mol for the dogfish enzyme and 10.2 kcal/mol for the bovine, whereas delta H++ values were only slightly lower in the dogfish enzyme for the other two substrates. For all substrates, the deacylation rate constant (kcat) was greater with dogfish chymotrypsin than bovine. However, the free energies of activation (delta G++) for deacylation were nearly equal between the two enzymes for each of the substrates.

Acylation↗
PubMed1994

Analysis of the secretory glycoproteins of the subcommissural organ of the dogfish (Scyliorhinus canicula).

The subcomissural organ (SCO) is an ancient and conserved brain gland secreting glycoproteins into the cerebrospinal fluid which condense to form Reissner's fiber (RF). The SCO of an elasmobranch species, the dogfish Scyliorhinus canicula, was investigated applying morphological and biochemical methods. The SCO of 34 dogfishes were processed for the following techniques: (1) conventional transmission electron microscopy; (2) light and electron microscopy lectin histochemistry (Concanavalin A, Con A; wheat germ agglutinin, WGA; Limax flavus agglutinin, LFA); (3) light and electron microscopy immunocytochemistry using antisera raised against the glycoproteins of the bovine RF (anti-bovine RF), and the secretory material of the dogfish SCO (anti-dogfish SCO). The former reacts with the SCO of virtually all vertebrate species [19] (conserved epitopes); the latter reacts only with the SCO of elasmobranchs [Cell Tissue Res., 276 (1994) 515-522] (class-specific epitopes). At the light microscopic level both antisera immunoreacted selectively with the SCO and RF; no other structure of the central nervous system was reactive. Within the SCO the binding sites for WGA (affinity = glucosamine, sialic acid) and LFA (affinity = sialic acid) displayed the same density and intracellular distribution. At the ultrastructural level two types of granules were distinguished. Type I granules (200-400 nm) were numerous, reacted with both antisera, bound WGA but not Con A. Type II granules (0.8-1.8 microns) reacted with the anti-bovine RF serum but not with the anti-dogfish SCO serum, bound Con A and WGA. The content of dilated cisternae of the rough endoplasmic reticulum reacted with both antisera and bound Con A; it did not bind WGA. The SCOs of 4500 dogfishes were extracted in ammonium bicarbonate. This extract was used for SDS-PAGE and blotting. Blots were processed for immunolabeling using anti-bovine RF and anti-dogfish SCO sera, and for lectin binding (Con A, WGA and LFA). The anti-bovine RF revealed four compounds with apparent molecular weights of 750, 380, 145 and 35 kDa. The two former also reacted with the anti-dogfish SCO serum and bound Con A. Only the 380 kDa compound bound WGA and LFA. The findings indicate that both the conserved and the class-specific epitopes are part of the same compounds (780, 380 kDa), which would be stored in type I granules. The lectin binding properties of these compounds point to the 780 kDa compound as a precursor form and the 380 kDa polypeptide as a processed form.

Animals↗
PubMed2002

Purification, characterization, and biological activity of insulins from the spotted dogfish, Scyliorhinus canicula, and the hammerhead shark, Sphyrna lewini.

Insulin was purified from pancreatic extracts of two elasmobranch species belonging to different families in the order Carcharhiniformes, the European spotted dogfish, Scyliorhinus canicula (Scyliorhinidae), and the hammerhead shark, Sphyrna lewini (Carcharhinidae). The amino acid sequence of dogfish insulin was established as A-chain GIVDHCCRNT(10)CSLYDLEGYC(20)NQ and B-chain LPSQHLCGSH(10)LVETLYFVCG(20)QKGFYYVPKV(30). The primary structure of hammerhead shark insulin was similar to that of dogfish insulin with only 2 amino acid substitutions at A8 (R --> H) and B30 (V --> I). The elasmobranch insulins were markedly different from human insulin (17 amino acid substitutions) but all the residues in human insulin that are believed to be important in determining the receptor binding conformation (B6, B8, B11, B13, B23, B24, B25, A2, A3, and A19) have been conserved in the elasmobranch insulins with the exception of the conservative substitution Phe --> Tyr at B25. Consistent with this, dogfish and human insulin showed almost identical binding affinity to the recombinant solubilized human insulin receptor (K(D) values of 14.0 and 18.6 pM, respectively; relative potency 133%). Previous studies have shown that bovine insulin produces severe and sustained hypoglycemia in elasmobranchs but the effect is of slow onset. Bolus arterial injections of dogfish insulin (10 nmol x kg(-1)) into unanesthetized, fasting dogfish (n = 9) produced no changes in blood glucose, 3-hydroxybutyrate, and acetoacetate concentrations over a 4-h period. In a second series of experiments (n = 7), dogfish insulin (10 nmol x kg(-1)) produced a significant (P < 0.05) fall in blood glucose after 12 h that persisted for at least 48 h, but no change in ketone body concentrations. The data indicate that the metabolic actions of an endogenous elasmobranch insulin in an elasmobranch are similar to those previously described for mammalian insulin.

3-Hydroxybutyric Acid↗
PubMed1981

Laser-light scattering diffusion measurements on brain microtubule protein from dogfish (Squalus acanthus) and beef.

Laser photon correlation spectroscopy and analytical ultracentrifugation were used to compare the equilibrium properties of disassembled, assembly-competent, brain microtubule protein from dogfish (Squalus acanthus) and beef. Analytical ultracentrifugation confirmed that assembly-competent bovine material at 4 degrees C, purified in the presence of glycerol through 2 cycles of assembly and disassembly, consisted of 6 S (dimer) and 35 S (ring) components, whereas assembly-competent dogfish material prepared in the same way was composed primarily of 6 S protein. By means of photon correlation spectroscopy, z-average diffusion coefficients (D'20, w) of 0.55 (+/- 0.04) x 10(-11) m2 s-1 (beef) and 1.27 (+/- 0.11) x 10(-11) m2 s-1 (dogfish) were measured at 4 degrees C for the twice-cycled assembly competent microtubule protein. Although D'20, w values for dogfish material are significantly higher than those for beef, they depart from the calculated value of 5.0 x 10(-11) m2 s-1 for a pure 6 S (dimer) solution. Microtubule accessory proteins were detectable on sodium dodecyl sulphate/polyacrylamide gels of dogfish microtubule protein. By fitting photocount autocorrelation functions to a 2-particle (dimer-ring) model it was estimated that the presence in a solution of assembly-competent dogfish microtubule protein of less than 1 ring per 250 dimers could account for the measured z-average diffusion coefficient. The temperature sensitivity of D'20, w showed that dogfish brain microtubule protein polymerized at lower temperatures than samples prepared by the same methods from beef brain.

Animals↗
PubMed1999

Cardiovascular control via angiotensin II and circulating catecholamines in the spiny dogfish, Squalus acanthias.

The contributions of circulating angiotensin II (Ang II) and catecholamines to cardiovascular control in the spiny dogfish were investigated by monitoring the effects of exogenous and endogenous dogfish [Asn1, Pro3, Ile5]-Ang II (dfAng II) on plasma catecholamine levels and blood pressure regulation. Bolus intravenous injections of dfAng II (30-1200 pmol kg-1) elicited dose-dependent increases in plasma adrenaline and noradrenaline concentrations, caudal artery pressure (PCA), and systemic vascular resistance (RS), and a decrease in cardiac output (Q). Similar injections of Ang II in dogfish pre-treated with the alpha-adrenoceptor antagonist yohimbine (4 mg kg-1) also elicited dose-dependent increases in plasma catecholamine levels yet the cardiovascular effects were abolished. Dogfish treated with yohimbine were hypotensive and had elevated levels of plasma Ang II and catecholamines. Intravenous injection of the smooth muscle relaxant papaverine (10 mg kg-1) elicited a transient decrease in PCA and RS, and increases in plasma Ang II and catecholamine levels. In dogfish first treated with lisinopril (10(-4) mol kg-1), an angiotensin converting enzyme inhibitor, papaverine treatment caused a more prolonged and greater decrease in PCA and RS, an attenuated increase in plasma catecholamines, and no change in plasma Ang II. By itself, lisinopril treatment had little effect on PCA, and no effect on RS, plasma Ang II or catecholamines. In yohimbine-treated dogfish, papaverine treatment elicited marked decreases in PCA, RS, and Q, and increases in plasma Ang II and catecholamines. Among the three papaverine treatments, there was a positive linear relationship between plasma Ang II and catecholamine concentrations, and the cardiovascular and hormonal changes were most pronounced in the yohimbine + papaverine treatment. Therefore, under resting normotensive conditions, while Ang II does not appear to be involved in cardiovascular control, catecholamines play an important role. However, during a hypotensive stress elicited by vascular smooth muscle relaxation. Ang II indirectly contributes to cardiovascular control by dose-dependently stimulating catecholamine release.

Adrenergic alpha-Antagonists↗
PubMed1997

Digestion of the 1-O-alkyl diacylglycerol ethers of Atlantic dogfish liver oils by Atlantic salmon Salmo salar.

Dogfish (Squalus acanthias) liver poses a waste disposal problem in Canada because it is not utilized for any commercial purpose. The liver of Atlantic dogfish, which is often up to 20% of the weight of the fish, contains 40-70% oil. The oil contains about 30-40% 1-O-alkyl diacylglycerol ethers (DAGE) which render it unacceptable for human use, and it has also not been considered satisfactory for animal feed use. Polyunsaturated fatty acids (20:5n-3 and 22:6n-3) are present in dogfish liver oils at levels comparable to those in herring oil. Dogfish liver oil could be a source of essential fatty acids for Atlantic salmon (Salmo salar), but their ability to hydrolyze DAGE from dogfish oil has not been examined. Experiments were designed to measure the digestibility of fatty acids of DAGE in salmon. The fatty acid moieties were liberated by the digestive enzymes of the fish and made readily available as a source of energy. The 1-O-alkylglycerol ether moiety was absorbed to a small extent but should not constitute a health problem in either the fish or the human fish consumer. The long-chain polyunsaturated fatty acids were particularly well absorbed, with an apparent digestibility in salmon of 87-95% when feeding on dogfish liver oil. The total fatty acids and other lipids were in fact both absorbed to the extent of approximately 85%.

Animals↗
PubMed1984

The effect of adenyl compounds on the heart of the dogfish, Scyliorhinus canicula.

The effects of adenyl compounds were examined on dogfish atria and ventricles. Adenosine, ATP, beta, gamma-methylene ATP ( APPCP ) and 2-chloroadenosine produced negative inotropic and chronotropic effects on the dogfish atrium, which were antagonized by 8-phenyltheophylline, a P1- purinoceptor antagonist. alpha-beta-Methylene ATP ( APCPP ), which is resistant to degradation, did not produce a similar inhibitory response in the dogfish atrium. Atropine did not affect the responses to adenosine, indicating that adenosine did not produce its effects indirectly by the release of acetylcholine. The effects of adenosine and ATP were not potentiated by dipyridamole, which blocks adenosine uptake; and 2-chloroadenosine, which is reported to be resistant to uptake and deamination, was equipotent with adenosine; this suggests the absence of an adenosine uptake system. Dogfish ventricles were insensitive to adenyl compounds. Adrenaline, noradrenaline and acetylcholine produced positive inotropic effects on the ventricle. It is concluded that inhibitory P1- purinoceptors are present in the dogfish atrium. However, adenyl compounds had no direct action on the contractility of the dogfish ventricle.

Adenosine↗
PubMed1984

Changes in activity and ventilation in response to hypoxia in unrestrained, unoperated dogfish (Scyliorhinus canicula L.).

daily activity cycles, together with changes in activity and ventilation frequency in response to hypoxia (PO2 about 8 kPa), have been measured in unrestrained, unoperated dogfish. Continuous recording of activity over 48 h reveals that dogfish are essentially nocturnal, being three to four times more active at night than during the day. In relatively inactive, diurnal dogfish, rapid reduction of environmental PO2 does not cause any significant increase in swimming activity, whereas prolonged hypoxia actually appears to suppress activity. In more active, nocturnal dogfish, rapid reduction of environmental PO2 causes an immediate reduction in activity which remains suppressed throughout the hypoxic period. It is concluded therefore that increases in circulating catecholamines in response to hypoxia are the result of hypoxia alone, rather than of any increase in locomotory activity. In resting diurnal dogfish, ventilation frequency is lower than has previously been reported for this species and, contrary to previous reports, increases markedly by 49% in response to hypoxia. It appears that in previous studies on confined dogfish, respiratory frequency, and probably ventilation volume, may have been elevated to near maximum levels even in 'resting' normoxic fish. This may have profound effects on so-called resting values for oxygen transfer in this species.

Animals↗
PubMed1991

Identification and localization of a dogfish homolog of human cystic fibrosis transmembrane conductance regulator.

Chloride channels in the apical plasma membrane of cells in the dogfish rectal gland have served as a model system for the study of regulation of chloride flux by changes in intracellular cyclic AMP levels. Similar regulation by cyclic AMP has been described for channels in cells of human secretory epithelia where defective regulation by cyclic AMP-dependent protein phosphorylation is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). We have isolated a cDNA clone from the rectal gland encoding a protein that is 72% identical to the human CFTR. One of the major phosphorylation sites in CFTR is absent in the dogfish protein. The dogfish protein has, however, four additional putative substrate sites for the cyclic AMP-dependent protein kinase. A peptide antibody, which was raised against an amino acid sequence common to both the human and dogfish CFTR sequences, recognizes proteins with similar molecular masses (160 kDa) in the dogfish gland and in mammalian lung. Immunolocalization studies with this antibody show that the putative dogfish CFTR is localized to the apical membrane of cells lining the lumen of the rectal gland.

Amino Acid Sequence↗
PubMed1982

Glucose transport across ocular barriers of the spiny dogfish, Squalus acanthias.

Evidence is presented demonstrating that in the dogfish, Squalus acanthias, D-glucose is transported from the blood to the ocular fluid compartments by a mechanism that is consistent with carrier-facilitated transport. Across the dogfish aqueous barrier D-glucose is transported 8.4 times faster than L-glucose, whereas this D/L transport ratio is only 5.5 in the rat. Similarly, the D/L transport ratio is 12.7 across the dogfish vitreous barrier and only 6.1 across this barrier in the rat. It is estimated that per unit area of vitreous barrier, the rat transports D-glucose faster than the dogfish but also has a greater passive permeability, as measured by L-glucose, and transport is therefore less efficient. Urea transport was found to be faster than L-glucose transport, suggesting a transport mechanism for urea other than simple diffusion. The sectional analysis of frozen vitreous humor indicated that the lens of the dogfish is supplied with D-glucose from both the ciliary epithelium and across the retinal pigment epithelium, while the retina receives D-glucose primarily across the pigment epithelium.

Animals↗
PubMed2002

Structure and expression of three Emx genes in the dogfish Scyliorhinus canicula: functional and evolutionary implications.

We report the characterization of three Emx genes in a chondrichthyan, the dogfish Scyliorhinus canicula. Comparisons of these genes with their osteichthyan counterparts indicate that the gnathostome Emx genes belong to three distinct orthology classes, each containing one of the dogfish genes and either the tetrapod Emx1 genes (Emx1 class), the osteichthyan Emx2 genes (Emx2 class) or the zebrafish Emx1 gene (Emx3 class). While the three classes could be retrieved from the pufferfish genome data, no indication of an Emx3-related gene in tetrapods could be found in the databases, suggesting that this class may have been lost in this taxon. Expression pattern comparisons of the three dogfish Emx genes and their osteichthyan counterparts indicate that not only telencephalic, but also diencephalic Emx expression territories are highly conserved among gnathostomes. In particular, all gnathostomes share an early, dynamic phase of Emx expression, spanning presumptive dorsal diencephalic territories, which involves Emx3 in the dogfish, but another orthology class, Emx2, in tetrapods. In addition, the dogfish Emx2 gene shows a highly specific expression domain in the cephalic paraxial mesoderm from the end of gastrulation and throughout neurulation, which suggests a role in the segmentation of the cephalic mesoderm.

Amino Acid Sequence↗
PubMed2001

The effects of endothelin-1 on the cardiorespiratory physiology of the freshwater trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias).

The aim of the present study was to evaluate the effects of endothelin-l-elicited cardiovascular events on respiratory gas transfer in the freshwater rainbow trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias). In both species, endothelin-1 (666 pmol kg(-1)) caused a rapid (within 4 min) reduction (ca. 30-50 mmHg) in arterial blood partial pressure of O2. The effects of endothelin-1 on arterial blood partial pressure of CO2 were not synchronised with the changes in O2 partial pressure and the responses were markedly different in trout and dogfish. In trout, arterial CO2 partial pressure was increased transiently by approximately 1.0 mmHg but the onset of the response was delayed and occurred 12 min after endothelin-1 injection. In contrast, CO2 partial pressure remained more-or-less constant in dogfish after injection of endothelin-1 and was increased only slightly (approximately 0.1 mmHg) after 60 min. Pre-treatment of trout with bovine carbonic anhydrase (5 mg ml(-1)) eliminated the increase in CO2 partial pressure that was normally observed after endothelin-1 injection. In both species, endothelin-1 injection caused a decrease in arterial blood pH that mirrored the changes in CO2 partial pressure. Endothelin-1 injection was associated with transient (trout) or persistent (dogfish) hyperventilation as indicated by pronounced increases in breathing frequency and amplitude. In trout, arterial blood pressure remained constant or was decreased slightly and was accompanied by a transient increase in systemic resistance, and a temporary reduction in cardiac output. The decrease in cardiac output was caused solely by a reduction in cardiac frequency; cardiac stroke volume was unaffected. In dogfish, arterial blood pressure was lowered by approximately 10 mmHg at 6-10 min after endothelin-1 injection but then was rapidly restored to pre-injection levels. The decrease in arterial blood pressure reflected an increase in branchial vascular resistance (as determined using in situ perfused gill preparations) that was accompanied by simultaneous decreases in systemic resistance and cardiac output. Cardiac frequency and stroke volume were reduced by endothelin-1 injection and thus both variables contributed to the changes in cardiac output. We conclude that the net consequences of endothelin-1 on arterial blood gases result from the opposing effects of reduced gill functional surface area (caused by vasoconstriction) and an increase in blood residence time within the gill (caused by decreased cardiac output.

Animals↗