The corpuscles of Stannius and calcium regulation in the North American eel (Anguilla rostrata LeSueur)

1974 ◽  
Vol 23 (2) ◽  
pp. 127-135 ◽  
Author(s):  
James C. Fenwick
Keyword(s):  
North American ◽  
Calcium Regulation ◽  
Anguilla Rostrata ◽  
American Eel ◽  
Corpuscles Of Stannius ◽  
The North

Description and first occurrence of Myxidium zealandicum (Protozoa: Myxosporidia) in the North American eel Anguilla rostrata LeSueur

1977 ◽  
Vol 55 (1) ◽  
pp. 52-59 ◽  
Author(s):  
M. P. Komourdjian ◽  
W. C. Hulbert ◽  
J. C. Fenwick ◽  
T. W. Moon
Keyword(s):  
North American ◽  
Kidney Tissue ◽  
Quebec City ◽  
Anguilla Rostrata ◽  
Fast Green ◽  
American Eel ◽  
The North ◽  
First Occurrence ◽  
Scanning Electron ◽  
St Lawrence River

Myxidium zealandicum Hine, 1975 is described from gills and kidney of the North American eel Anguilla rostrata collected from the St. Lawrence River near Quebec City and Cornwall. Cysts of M. zealandicum on gills measured up to 1 by 2 mm and in kidneys up to 15 by 20 mm. In addition to single spherical cysts, several polymorphous forms were also observed on the gills. Polymorphous cysts were not found in the kidney. Different stages of spore development were evident in gill cysts and were differentiated by means of a lead hematoxylin – fast green stain. Number and pattern of spore striations were examined by scanning electron microscopy and were highly variable. The invasion of the parasite into kidney tissue appeared to result in less physiological damage to the host than did gill invasion. The existence of this parasite, previously found in eel species in New Zealand, in a North American eel species is discussed.

The fine structure of sporogony in Myxidium zealandicum (Protozoa: Myxosporidia)

1977 ◽  
Vol 55 (2) ◽  
pp. 438-447 ◽  
Author(s):  
W. C. Hulbert ◽  
M. P. Komourdjian ◽  
T. W. Moon ◽  
J. C. Fenwick
Keyword(s):  
Fine Structure ◽  
Germ Cell ◽  
North American ◽  
Polar Capsule ◽  
Anguilla Rostrata ◽  
Transport Function ◽  
American Eel ◽  
The North ◽  
Spherical Structures ◽  
Asynchronous Maturation

Studies of the ultrastructure of the trophozoite (plasmodium) and the process of sporogony and polar capsule development of Myxidium zealandicum from gill and kidney of the North American eel Anguilla rostrata are described. Although the basic steps and characteristics of sporogony are similar to those previously reported for other myxosporidians, we report three new and significant observations in this study: (1) the identification of a uninucleate germ cell for the binucleate sporocyst; (2) the asynchronous maturation of polar capsules within a single sporocyst; and (3) the existence of a mitochondrial layer at the periphery of the Plasmodium that may have a transport function. We also observed cylindrical and spherical structures, either of which might be the primordium of the polar capsule, but we were unable to resolve this problem. These observations are discussed with reference to previous descriptions of myxosporidians.

scholarly journals Depression Of Whole-Body Calcium Uptake During Acute Hypercalcaemia In American Eel, Anguilla Rostrata, is Mediated Exclusively by Corpuscles of Stannius

1989 ◽  
Vol 147 (1) ◽  
pp. 249-261 ◽  
Author(s):  
S. F. PERRY ◽  
D. SEGUIN ◽  
F. P. J. G. LAFEBER ◽  
S. E. WENDELAAR BONGA ◽  
J. C. FENWICK
Keyword(s):  
Calcium Influx ◽  
Whole Body ◽  
Magnesium Concentration ◽  
Anguilla Rostrata ◽  
American Eel ◽  
Arterial Infusion ◽  
Rapid Reduction ◽  
Corpuscles Of Stannius ◽  
Total Magnesium

1. The role of the corpuscles of Stannius (CS) in acute modulation of wholebody calcium influx (JinCa) in American eel, Anguilla rostrata, was investigated by (i) assessing the effects of stanniectomy on JinCa and plasma total calcium concentration ([Catot]), (ii) comparing the abilities of sham-operated and stanniectomized eels to reduce JinCa during artificially induced hypercalcaemia, and (iii) monitoring the effects of homologous hypocalcin (a 54×103Mr glycoprotein injection on JinCa 2. Stanniectomy (STX) caused a pronounced elevation of JinCa and hypercalcaemia measured 7 days after surgery. 3. When hypercalcaemia was induced by intra-arterial infusion of CaCl2, a treatment known to cause degranulation of the CS and the specific release of hypocalcin, JinCa was reduced significantly within 1 h in intact fish. NaCl infusion did not affect plasma [Catot] or JinCa in any group tested. 4. Stanniectomy prevented the reduction of JinCa associated with the hypercalcaemia induced by CaCl2 infusion. 5. Intra-arterial infusion of MgCl2 caused a significant elevation of plasma total magnesium concentration [Mgtot] but did not alter JinCa. 6. Intra-arterial infusion of hypocalcin (l8.5 nmolkg−1 body mass) into intact eels decreased JinCa to an extent similar to that seen following artificially induced hypercalcaemia. 7. We conclude that the rapid reduction of JinCa during experimental hypercalcaemia is mediated by hypocalcin released from the corpuscles of Stannius and suggest that calcitonin, another putative hypocalcaemic hormone, is not involved. The results are discussed with respect to the relative importance of hypocalcin and calcitonin as hypocalcaemic hormones in fish.

A detailed investigation of the cytoplasmic cortisol-binding receptor of North American eel (Anguilla rostrata) tissues

1984 ◽  
Vol 62 (10) ◽  
pp. 991-997 ◽  
Author(s):  
John A. DiBattista ◽  
A. Z. Mehdi ◽  
Thomas Sandor
Keyword(s):  
Glucocorticoid Receptor ◽  
North American ◽  
Glucocorticoid Receptors ◽  
Thermodynamic Characteristics ◽  
Relative Mass ◽  
Anguilla Rostrata ◽  
Hydroxyl Groups ◽  
American Eel ◽  
Receptor Complexes

The in vitro binding of tritiated cortisol to ammonium sulfate precipitate (35% saturation) prepared from the gill and gut mucosal cytosol of the North American eel (Anguilla rostrata) was investigated. The sodium molybdate stabilized cytoplasmic preparations bound tritiated cortisol with the following parameters: gill, equilibrium dissociation constant (KD) = 3.7 ± 0.4 nM, (± SEM; n = 4), the maximum concentration of binding sites (Nmax) = 294 ± 26 fmol/mg protein; gut, KD = 5.2 ± 0.4 nM, Nmax = 1085 ± 288 fmol/mg protein. The [3H]cortisol–receptor complexes sedimented on linear (16–41% w/v) glycerol density gradients in single peaks at 6.7S–7.0S or 3.0S–3.6S in hypo- or hyper-tonic (± 0.4 M KCl) gradients, respectively. Sephacryl S-300 column chromatography of the hormone–receptor complex yielded the following hydrodynamic parameters: gill, relative mass (Mr) = 292 000 daltons, Stokes radius (Rs) = 78.7 Å(1 Å = 0.1 nm), frictional ratio (f/f0) = 1.79; gut, Mr = 242 000 daltons, Rs = 68.8 Å, f/f0 = 1.66. Competition studies revealed the following competitive hierarchies of radioinert steroids vis-à-vis the inhibition of [3H]cortisol binding to the receptor with both tissues: cortisol > 11-deoxycortisol > 21-deoxycortisol > 17α-hydroxyprogesterone [Formula: see text] corticosterone [Formula: see text] 11-deoxycorticosterone > 11β-hydroxyprogesterone. Aldosterone, cortisone, progesterone, or promegestone (R5020) hardly competed. These findings underline the importance of the C-17, C-21, and C-11 hydroxyl groups in receptor binding. Hydroxylation of progesterone in positions C-17, C-21, and C-11 contributed free energy changes (ΔG) of −5.8 to −6.2, −3.1 to −3.9, and −1.3 kJ/mol, respectively, to the binding of steroids to the eel glucocorticoid receptor. From these data we conclude that the piscine cortisol receptor is different from other vertebrate glucocorticoid receptors because of its physical and thermodynamic characteristics and its function in mediating electrolyte homeostatic action of a typical glucocorticoid in the transport epithelia. It is conceivable that the fish glucocorticoid receptor is an ancestral form of the glucocorticoid and (or) mineralocorticoid receptors of vertebrates.

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