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.

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.

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.

Occurrence of American Eels, Anguilla rostrata, in Waters Overlying the Eastern North American Continental Shelf

1973 ◽  
Vol 30 (11) ◽  
pp. 1752-1755 ◽  
Author(s):  
Charles A. Wenner
Keyword(s):  
Continental Shelf ◽  
Chesapeake Bay ◽  
North American ◽  
Cape Cod ◽  
Anguilla Rostrata ◽  
American Eel ◽  
Morphometrical Analysis ◽  
Assateague Island ◽  
American Eels

Eleven reproductively maturing specimens of the American eel, Anguilla rostrata, were collected during three independent off-shore trawling operations. Three females were taken on December 5, 1967 southeast of the mouth of Chesapeake Bay in 10–13 fathoms, one male and one female on November 5, 1969 southeast of Cape Cod in 35–45 fathoms, and six females east of Assateague Island on December 22, 1971 in 5 fathoms. Morphometrical analysis showed that the specimens were within the range of "silver" phase of Anguilla rostrata. Gonadal observations were made on all specimens.

Ultrastructural study of the adrenocortical homologue in freshwater and seawater adapted eels

1978 ◽  
Vol 36 (2) ◽  
pp. 586-587
Author(s):  
Tapan Kumar Bhattacharyya ◽  
David Gordon Butler
Keyword(s):  
Fine Structure ◽  
Experimental Studies ◽  
Mature Female ◽  
American Eel ◽  
Endocrine Organ ◽  
The North ◽  
Metabolic Role ◽  
Silver Eels ◽  
Cacodylate Buffer

The teleost fishes have been extensively utilized to explore the biochemical nature of adrenocortical steroids, pathways of steroidogenesis and the metabolic role of adrenocortical steroids. The adrenocortical homologue (AH) has been localized in more than two hundred species of teleosts, although the fine structure of teleost AH has been studied only in the goldfish. It seemed to be of interest to investigate the normal fine structure of this endocrine organ in another zoologically important teleost species, the north American eel (Anguilla rostrata) as a baseline for experimental studies. This animal being a euryhaline species, the AH ultrastructure of animals exposed to artificial seawater for a long period (1 1/2 years) was also examined.Mature female silver eels held in freshwater(FW) and seawater(SW) aquaria were anesthetized and perfused with glutaraldehyde in phosphate buffer or formaldehyde-glutaraldehyde in cacodylate buffer, and glutaraldehyde containing 0. 2% digitonin for demonstration of cholesterol.

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