scholarly journals Developmental changes in the half-life of acetylcholine receptors in the myotomal muscle of Xenopus laevis.

1990 ◽  
Vol 426 (1) ◽  
pp. 281-296 ◽  
Author(s):  
M W Cohen ◽  
P F Frair ◽  
C Cantin ◽  
G Hébert
Keyword(s):  
Xenopus Laevis ◽  
Half Life ◽  
Acetylcholine Receptors ◽  
Developmental Changes ◽  
Myotomal Muscle

scholarly journals Developmental changes of purinergic control of intestinal motor activity during metamorphosis in the African clawed frog, Xenopus laevis

2007 ◽  
Vol 292 (5) ◽  
pp. R1916-R1925 ◽  
Author(s):  
Monika Sundqvist
Keyword(s):  
Xenopus Laevis ◽  
Motor Activity ◽  
Receptor Antagonist ◽  
Circular Muscle ◽  
Developmental Changes ◽  
Disulfonic Acid ◽  
Developmental Phase ◽  
African Clawed Frog ◽  
Low Concentrations ◽  
Clawed Frog

Little is known about the purinergic regulation of intestinal motor activity in amphibians. Purinergic control of intestinal motility is subject to changes during development in mammals. The aim of this study was to investigate purinergic control of intestinal smooth muscle in the amphibian Xenopus laevis and explore possible changes in this system during the developmental phase of metamorphosis. Effects of purinergic compounds on mean force and contraction frequency in intestinal circular muscle strips from prometamorphic, metamorphic, and juvenile animals were investigated. Before metamorphosis, low concentrations of ATP reduced motor activity, whereas the effects were reversed at higher concentrations. ATP-induced relaxation was not inhibited by the P2-receptor antagonist pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS) but was blocked by the ecto-nucleotidase inhibitor 6- N, N-diethyl-d-β,γ-dibromomethylene ATP ( ARL67256 ), indicating that an ATP-derived metabolite mediated the relaxation response at this stage. Adenosine induced relaxation before, during, and after metamorphosis, which was blocked by the A1-receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX). The stable ATP-analog adenosine 5′-[γ-thio]-triphosphate (ATPγS) and 2-methylthioATP (2-MeSATP) elicited contractions in the circular muscle strips in prometamorphic tadpoles. However, in juvenile froglets, 2-MeSATP caused relaxation, as did ATPγS at low concentrations. The P2Y11/P2X1-receptor antagonist NF157 antagonized the ATPγS-induced relaxation. The P2X-preferring agonist α-β-methyleneadenosine 5′-triphosphate (α-β-MeATP) evoked PPADS-sensitive increases in mean force at all stages investigated. This study demonstrates the existence of an adenosine A1-like receptor mediating relaxation and a P2X-like receptor mediating contraction in the X. laevis gut before, during, and after metamorphosis. Furthermore, the development of a P2Y11-like receptor-mediated relaxation during metamorphosis is shown.

scholarly journals The effects of environmental temperature on the properties of myofibrillar adenosine triphosphatase from various species of fish

1973 ◽  
Vol 133 (4) ◽  
pp. 735-738 ◽  
Author(s):  
Ian A. Johnston ◽  
Neil Frearson ◽  
Geoffrey Goldspink
Keyword(s):  
Low Temperatures ◽  
Half Life ◽  
Adenosine Triphosphatase ◽  
Environmental Temperature ◽  
Cold Water ◽  
Warm Water ◽  
Adenosine Triphosphatase Activity ◽  
Water Fish ◽  
Different Temperatures ◽  
Myotomal Muscle

1. Myofibrillar adenosine triphosphatase (ATPase) activities were measured for white myotomal muscle of 19 species of fish. 2. The activity was measured at different temperatures and after periods of preincubation at 37°C. 3. The inactivation half-life at 37°C depended on environmental temperature, increasing as the temperature increased. 4. Cold-water fish had higher myofibrillar adenosine triphosphatase activity at low temperatures than had warm-water fish. 5. The significance of these results is discussed.

scholarly journals Developmental Changes in Lectin-Binding Patterns of Three Nasal Sensory Epithelia in Xenopus laevis

2011 ◽  
Vol 294 (5) ◽  
pp. 839-846 ◽  
Author(s):  
Daisuke Endo ◽  
Yoshio Yamamoto ◽  
Nobuaki Nakamuta ◽  
Kazuyuki Taniguchi
Keyword(s):  
Xenopus Laevis ◽  
Lectin Binding ◽  
Developmental Changes ◽  
Sensory Epithelia

scholarly journals Wall following in Xenopus laevis is passive

2017 ◽  
Author(s):  
Sara Hänzi ◽  
Hans Straka
Keyword(s):  
Xenopus Laevis ◽  
Shallow Water ◽  
Spatial Learning ◽  
Developmental Stages ◽  
Confounding Factor ◽  
Developmental Changes ◽  
Infrared Light ◽  
Total Distance ◽  
Summary Statement ◽  
Wall Following

AbstractThe tendency of animals to follow boundaries within their environment can serve as a strategy for spatial learning or defence. We examined whether animals of Xenopus laevis employ such a strategy by characterizing their swimming behaviour. We also investigated potential developmental changes, the influence of tentacles, which some of the developmental stages possess, and whether wall-following is active (animals seek out wall contact) or passive. Animals’ swimming movements were recorded with a camera from above in a square tank with shallow water and their trajectories were analysed especially for proximity to the nearest wall. With the exception of young larvae, in which wall following was less strong, the vast majority of animals – tadpoles and froglets – spent more time near the wall than what would be expected from the proportion of the area near the wall. The total distance covered was not a confounding factor. Wall following was also not influenced by whether the surrounding of the tank was black or white, illuminated by infrared light, or by the presence or absence of tentacles. Animals were stronger wall followers in smaller tanks. When given a choice in a convex tank to swim straight and leave the wall or turn to follow the wall, the animals consistently left the wall, indicating that wall following in Xenopus laevis is passive. This implies that wall following behaviour in Xenopus derives from constraints imposed by the environment (or the experimenter) and is unlikely a strategy for spatial learning or safety-seeking.Summary statement:Xenopus laevis tadpoles and froglets tend to swim along the walls of a square tank; but this wall following is passive – in a convex tank, they leave the wall.

scholarly journals Stabilization of Acetylcholine Receptors by Exogenous ATP and Its Reversal by cAMP and Calcium

1997 ◽  
Vol 138 (1) ◽  
pp. 159-165 ◽  
Author(s):  
James P. O'Malley ◽  
Charlotte T. Moore ◽  
Miriam M. Salpeter
Keyword(s):  
Neuromuscular Junction ◽  
Half Life ◽  
Acetylcholine Receptors ◽  
Muscle Cells ◽  
Muscle Membrane ◽  
Intracellular Camp ◽  
Signaling Systems ◽  
Camp Analogue ◽  
Degradation Rates ◽  
The Stability

Innervation of the neuromuscular junction (nmj) affects the stability of acetylcholine receptors (AChRs). A neural factor that could affect AChR stabilization was studied using cultured muscle cells since they express two distinct populations of AChRs similar to those seen at the nmjs of denervated muscle. These two AChR populations are (in a ratio of 9 to 1) a rapidly degrading population (Rr) with a degradation half-life of ∼1 d and a slowly degrading population (Rs) that can alternate between an accelerated form (half-life ∼3–5 d) and a stabilized form (half-life ∼10 d), depending upon the state of innervation of the muscle. Previous studies have shown that elevation of intracellular cAMP can stabilize the Rs, but not the Rr. We report here that in cultured rat muscle cells, exogenous ATP stabilized the degradation half-life of Rr and possibly also the Rs. Furthermore, pretreatment with ATP caused more stable AChRs to be inserted into the muscle membrane. Thus, in the presence of ATP, the degradation rates of the Rr and Rs overlap. This suggests that ATP released from the nerve may play an important role in the regulation of AChR degradation. Treatment with either the cAMP analogue dibutyryl-cAMP (dB-cAMP) or the calcium mobilizer ryanodine caused the ATP-stabilized Rr to accelerate back to a half-life of 1 d. Thus, at least three signaling systems (intracellular cAMP, Ca2+, and extracellular ATP) have the potential to interact with each other in the building of an adult neuromuscular junction.

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