Directional and frequency saccular sensitivity of the little skate, Raja erinacea.

2011 ◽  
Vol 129 (4) ◽  
pp. 2472-2472
Author(s):  
Joseph A. Sisneros ◽  
Richard R. Fay
Keyword(s):  
Raja Erinacea

Cupula Motion in the Semicircular Canal of the Skate,RAJA ERINACEA An Experimental Investigation

1979 ◽  
Vol 87 (3-6) ◽  
pp. 528-538 ◽  
Author(s):  
Charles M. Oman ◽  
Lawrence S. Frishkopf ◽  
Moise H. Goldstein
Keyword(s):  
Experimental Investigation ◽  
Semicircular Canal ◽  
Raja Erinacea

Motor corollary discharge activity and sensory responses related to ventilation in the skate vestibulolateral cerebellum: implications for electrosensory processing

1996 ◽  
Vol 199 (3) ◽  
pp. 673-681 ◽  
Author(s):  
G Hjelmstad ◽  
G Parks ◽  
D Bodznick
Keyword(s):  
Noise Cancellation ◽  
Second Order ◽  
Corollary Discharge ◽  
Parallel Fiber ◽  
Large Percentage ◽  
Principal Function ◽  
Raja Erinacea ◽  
Dorsal Nucleus ◽  
Sensory Responses ◽  
Electrosensory Processing

The dorsal granular ridge (DGR) of the elasmobranch vestibulolateral cerebellum is the source of a parallel fiber projection to the electrosensory dorsal nucleus. We report that the DGR in Raja erinacea contains a large percentage of units with activity modulated by the animal's own ventilation. These include propriosensory and electrosensory units, responding to either ventilatory movements or the resulting electroreceptive reafference, and an additional population of units in which activity is phase-locked to the ventilatory motor commands even in animals paralyzed to block all ventilatory movements. A principal function of processing in the dorsal nucleus is the elimination of ventilatory noise in second-order electrosensory neurons. The existence of these ventilatory motor corollary discharge units, along with other DGR units responsive to ventilatory movements, suggests that the parallel fiber projection is involved in the noise cancellation mechanisms.

scholarly journals NOTES ON THE ATROPHY OF THE EYE OF RAJA ERINACEA

Science ◽  
1908 ◽  
Vol 28 (730) ◽  
pp. 930-931
Author(s):  
W. M. Smallwood
Keyword(s):  
Raja Erinacea

Carrier-mediated urea transport across the mitochondrial membrane of an elasmobranch (Raja erinacea) and a teleost (Oncorhynchus mykiss) fish

2008 ◽  
Vol 294 (6) ◽  
pp. R1947-R1957 ◽  
Author(s):  
T. M. Rodela ◽  
J. S. Ballantyne ◽  
P. A. Wright
Keyword(s):  
Oncorhynchus Mykiss ◽  
Mitochondrial Membrane ◽  
Liver Mitochondria ◽  
Reverse Direction ◽  
Maximal Velocity ◽  
Urea Transport ◽  
Submitochondrial Particles ◽  
Raja Erinacea ◽  
Urea Uptake ◽  
High Concentrations

In osmoregulating teleost fish, urea is a minor nitrogen excretory product, whereas in osmoconforming marine elasmobranchs it serves as the major tissue organic solute and is retained at relatively high concentrations (∼400 mmol/l). We tested the hypothesis that urea transport across liver mitochondria is carrier mediated in both teleost and elasmobranch fishes. Intact liver mitochondria in rainbow trout ( Oncorhynchus mykiss) demonstrated two components of urea uptake, a linear component at high concentrations and a phloretin-sensitive saturable component [Michaelis constant ( Km) = 0.58 mmol/l; maximal velocity ( Vmax) = 0.12 μmol·h−1·mg protein−1] at lower urea concentrations (<5 mmol/l). Similarly, analysis of urea uptake in mitochondria from the little skate ( Raja erinacea) revealed a phloretin-sensitive saturable transport ( Km= 0.34 mmol/l; Vmax= 0.054 μmol·h−1·mg protein−1) at low urea concentrations (<5 mmol/l). Surprisingly, urea transport in skate, but not trout, was sensitive to a variety of classic ionophores and respiration inhibitors, suggesting cation sensitivity. Hence, urea transport was measured in the reverse direction using submitochondrial particles in skate. Transport kinetics, inhibitor response, and pH sensitivity were very similar in skate submitochondrial particle submitochondrial particles ( Km= 0.65 mmol/l, Vmax= 0.058 μmol·h−1·mg protein−1) relative to intact mitochondria. We conclude that urea influx and efflux in skate mitochondria is dependent, in part, on a bidirectional proton-sensitive mechanism similar to bacterial urea transporters and reminiscent of their ancestral origins. Rapid equilibration of urea across the mitochondrial membrane may be vital for cell osmoregulation (elasmobranch) or nitrogen waste excretion (teleost).

Examination of Structural Differences in Gill Vasculature Among Some Batiod Elasmobranchs Using Corrosion Casting and SEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 1208-1209
Author(s):  
R.L. Sherman
Keyword(s):  
Corpus Cavernosum ◽  
Circulatory System ◽  
Gross Anatomy ◽  
Corrosion Casting ◽  
Mixed Species ◽  
Raja Erinacea ◽  
Scyliorhinus Canicula ◽  
Structural Differences ◽  
Vascular Arcade ◽  
Gill Structure

Classic studies of gill vasculature indicate the gross anatomy of elasmobranch gills is similar in most species, and in general, resembles those of teleosts. However, studies of fine gill structure examining arterio-arterial pathways in several species of batoid elasmobranchs (Order: Rajiiformes, Suborder: Myliobatoidei) have reported some structural differences. These differences include the presence, in urolophids (Urolophus jamaicensis, U. mucosus, U. paucimaculatus), of 1) a tip channel, possibly an extension of the afferent filament artery that runs along the top of the filament corpus cavernosum, and 2) a vascular arcade, a vessel which connects the afferent filament arteries of a hemibranch near the tip of each filament (FIG. I). Until recently these structures were believed to be unique to the urolophids as they were not previously found in either rajids (Raja erinacea, R. clavata) or the shark Scyliorhinus canicula. Animals of mixed species and sexes were collected, perfused, and acrylic casts made of the circulatory system.

Intracellular osmoregulatory role of amino acids and urea in marine elasmobranchs

1976 ◽  
Vol 230 (4) ◽  
pp. 925-931 ◽  
Author(s):  
RP Forster ◽  
L Goldstein
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Extracellular Fluid ◽  
Raja Erinacea ◽  
Urea Content ◽  
Intracellular Amino Acid ◽  
Trimethylamine Oxide ◽  
Total Amino Acids ◽  
Positive Materials

Little skates, Raja erinacea, and stingrays, Dasyatis americana, were gradually transferred over a period of 4-5 days from full strength to approximatley 50% seawater. Plasma and muscle osmolarity fell. Hematocrits were essentially unchanged. Extracellular fluid volume (ECF) of muscle, estimated as the chloride space, increased 70% during this period. Regulation of muscle cell volume was associated with sharp declines in cellular concentrations of total amino acids (ninhydrin-positive materials) and urea. The osmoregulatory importance of the free amino acid pool in erythrocytes and muscle was a particularly prominent feature in both species. Intracellular amino acid concentration in R. erinacea muscle fell from 214 to 144 mmol/liter during transfer to 50% seawater, urea from 398 to 264, and trimethylamine oxide (TMAO) dropped from 63.9 to 35.8 mmol/liter. TMAO plasma levels were similar in stingray and skate, but muscle TMAO concentrations were much higher in the former. Urea content in stingray plasma greatly exceeded that in R. erinacea-630 and 574 mmol/liter in two specimens-perhaps the highest recorded.

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