Left-right positioning of the adult rudiment in sea urchin larvae is directed by the right side

Development ◽  
2001 ◽  
Vol 128 (24) ◽  
pp. 4935-4948 ◽  
Author(s):  
Mizuki Aihara ◽  
Shonan Amemiya
Keyword(s):  
Cell Fate ◽  
Sea Urchin ◽  
Normal Development ◽  
Sea Urchins ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Larval Stages ◽  
Adult Rudiment ◽  
The Right ◽  
Pluteus Stage

Indirect-developing sea urchins eventually form an adult rudiment on the left side through differential left-right development in the late larval stages. Components of the adult rudiment, such as the hydropore canal, the hydrocoel and the primary vestibule, all develop on the left side alone, and are the initial morphological traits that exhibit left-right differences. Although it has previously been shown that partial embryos dissected in cleavage stages correctly determine the normal left-right placement of the adult rudiment, the timing and the mechanism that determine left-right polarity during normal development remain unknown. In order to determine these, we have carried out a series of regional operations in two indirect-developing sea urchin species. We excised all or a part of tissue on the left or right side of the embryos during the early gastrula stage and the two-armed pluteus stage, and examined the left-right position of the adult rudiment, and of its components. Excisions of tissues on the left side of the embryos, regardless of stage, resulted in formation of a left adult rudiment, as in normal development. By contrast, excisions on the right side of the embryos resulted in three different types of impairment in the left-right placement of the adult rudiment in a stage-dependent manner. Generally, when the adult rudiment was definitively formed only on the right side of the larvae, no trace of basic development of the components of the adult rudiment was found on the left side, indicating that a right adult rudiment results from reversal of the initial left-right polarity but not from a later inhibitory effect on the development of an adult rudiment. Thus, we suggest that determination of the left-right placement of the adult rudiment depends on a process, which is directed by the right side, of polarity establishment during the gastrula and the prism stages; however, but commitment of the cell fate to initiate formation of the adult rudiment occurs later than the two-armed pluteus stage.

Cerebrovascular characterization of clazosentan, the first nonpeptide endothelin receptor antagonist clinically effective for the treatment of cerebral vasospasm. Part I: Inhibitory effect on endothelinA receptor—mediated contraction

2005 ◽  
Vol 102 (6) ◽  
pp. 1101-1107 ◽  
Author(s):  
Hartmut Vatter ◽  
Michael Zimmermann ◽  
Veronika Tesanovic ◽  
Andreas Raabe ◽  
Lothar Schilling ◽  
...  
Keyword(s):  
Receptor Antagonist ◽  
Cerebral Vasospasm ◽  
Isometric Force ◽  
Inhibitory Effect ◽  
Affinity Constant ◽  
Dependent Manner ◽  
Content Type ◽  
The Right ◽  
Fine Print

Object. The central role of endothelin (ET)—1 in the development of cerebral vasospasm after subarachnoid hemorrhage is indicated by the successful treatment of this vasospasm in several animal models by using selective ETA receptor antagonists. Clazosentan is a selective ETA receptor antagonist that provides for the first time clinical proof that ET-1 is involved in the pathogenesis of cerebral vasospasm. The aim of the present investigation was, therefore, to define the pharmacological properties of clazosentan that affect ETA receptor—mediated contraction in the cerebrovasculature. Methods. Isometric force measurements were performed in rat basilar artery (BA) ring segments with (E+) and without (E−) endothelial function. Concentration effect curves (CECs) were constructed by cumulative application of ET-1 or big ET-1 in the absence or presence of clazosentan (10−9, 10−8, and 10−7 M). The inhibitory potency of clazosentan was determined by the value of the affinity constant (pA2). The CECs for contraction induced by ET-1 and big ET-1 were shifted to the right in the presence of clazosentan in a parallel dose-dependent manner, which indicates competitive antagonism. The pA2 values for ET-1 were 7.8 (E+) and 8.6 (E−) and the corresponding values for big ET-1 were 8.6 (E+) and 8.3 (E−). Conclusions. The present data characterize clazosentan as a potent competitive antagonist of ETA receptor—mediated constriction of the cerebrovasculature by ET-1 and its precursor big ET-1. These functional data may also be used to define an in vitro profile of an ET receptor antagonist with a high probability of clinical efficacy.

Reversible arrest of Artemia development by cadmium

1986 ◽  
Vol 64 (8) ◽  
pp. 1633-1641 ◽  
Author(s):  
Parvaneh Rafiee ◽  
Christopher O. Matthews ◽  
Joseph C. Bagshaw ◽  
Thomas H. MacRae
Keyword(s):  
Normal Development ◽  
Developmental Process ◽  
Inhibitory Effect ◽  
Microtubule Assembly ◽  
Abnormal Development ◽  
Dependent Manner ◽  
Physiological Changes ◽  
Molecular Aspects ◽  
Reduced Rate ◽  
Dose Dependent

Under normal conditions, an encysted Artemia embryo undergoes a developmental process that culminates in the gradual, uninterrupted emergence of the prenauplius from the cyst. The hatching membrane surrounding the emerged organism is then ruptured, usually beginning at the posterior end, and a motile nauplius is released. We have observed this process microscopically in the presence and absence of cadmium and report that cadmium disrupts Artemia development in a dose–dependent manner. At 0.1 μM, cadmium slows emergence but nauplii eventually resume rellatively normal development. Emergence and hatching are either delayed considerably or almost entirely prevented at 1 μM cadmium. Cadmium at 10 μM, completely arrests emergence but development continues at a reduced rate, eventually resulting in hatching of some organisms without need for complete emergence. If organisms exposed to 10 μM cadmium are washed, abnormally shaped emerged forms are released and many of these eventually hatch, although in an unusual manner. Cadmium at 10 μM causes complete, rapid precipitation of purified Artemia tubulin at 0 °C but cadmium at the lower concentrations tested has no apparent inhibitory effect on microtubule assembly. Although we do not know the actual cadmium–induced physiological changes that result in abnormal development of Artemia, our results indicate that we can now examine the interdependence of morphological and molecular aspects of Artemia development in a way not previously possible.

The Centriole-Centrosome Complex is Affected by Microgravity During Cell Division and in Cilia of Sea Urchin Embryos: Results from Space Flight Experiments

1998 ◽  
Vol 4 (S2) ◽  
pp. 1132-1133
Author(s):  
Heide Schatten ◽  
Amitabha Chakrabarti ◽  
Meghan Taylor ◽  
Michael Crosser ◽  
Kirk Mitchell
Keyword(s):  
Cell Division ◽  
Sea Urchin ◽  
Space Flight ◽  
Space Shuttle ◽  
Sea Urchins ◽  
Culture Conditions ◽  
Model System ◽  
Research Facility ◽  
Cilia Formation ◽  
Pluteus Stage

Sea urchins have been used for over a century as a remarkable animal model system in which to study cell, molecular, and developmental biology. The studies presented here have used sea urchin eggs and embryos for pioneering experiments to explore the effects of microgravity on the cytoskeleton during a space flight on the space shuttle Endeavor. The culture conditions followed those described previously utilizing the Aquatic Research Facility (ARF) to fertilize and culture eggs and embryos up to the pluteus stage under controlled temperature (12°C) and fixation conditions. To achieve a final fixation with 0.5% glutaraldehyde and 4μM taxol, concentrated fixation fluid was injected at preselected time points to preserve microtubules, centrioles, centrosomes, microfilaments, mitochondria, and cell membranes.The analysis of the results revealed that the centriole-centrosome complex during cell division and cilia formation showed alterations in samples that had been exposed to microgravity while control cells cultured in a centrifuge at lg in space and those cultured on ground appeared normal.

Effects of extracellular ATP on ICa, [Ca2+]i, and contraction in isolated ferret ventricular myocytes

1993 ◽  
Vol 264 (3) ◽  
pp. C702-C708 ◽  
Author(s):  
Y. Qu ◽  
H. M. Himmel ◽  
D. L. Campbell ◽  
H. C. Strauss
Keyword(s):  
Action Potential ◽  
Ventricular Myocytes ◽  
Ventricular Myocardium ◽  
Inhibitory Effect ◽  
Extracellular Atp ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
The Right

The effects of extracellular ATP on the voltage-activated "L-type" Ca current (ICa), action potential, resting and transient intracellular Ca2+ levels, and cell contraction were examined in enzymatically isolated myocytes from the right ventricles of ferrets. With the use of the whole cell patch-clamp technique, extracellular ATP (10(-7) to 10(-3) M) inhibited ICa in a time- and concentration-dependent manner. ATP decreased the peak amplitude of ICa without altering the residual current at the end of 500-ms clamp steps. The concentration-response relationship for ATP inhibition of ICa was well described by a conventional Michaelis-Menten relationship with a half-maximal inhibitory concentration of 1 microM and a maximal effect of 50%. Consistent with its inhibitory effect on ICa, ATP hyperpolarized the plateau phase and shortened the action potential duration. In fura-2-loaded myocytes, extracellular ATP did not change the resting myoplasmic Ca2+ levels; however, when current was elicited under voltage-clamp conditions, ATP both decreased the myoplasmic intracellular Ca2+ transient and inhibited the degree of cell shortening. Our results suggest that ATP could be a genuine and potent extracellular modulator of cardiac function in ferret ventricular myocardium.

scholarly journals Inhibitory Effects of Echinochrome A, Isolated from Shell of the Sea Urchin Anthocidaris crassispina, on Antigen-Stimulated Degranulation in Rat Basophilic Leukemia RBL-2H3 Cells through Suppression of Lyn Activation

2016 ◽  
Vol 11 (9) ◽  
pp. 1934578X1601100
Author(s):  
Tomohiro Itoh ◽  
Azusa Fujiwara ◽  
Masayuki Ninomiya ◽  
Toshimichi Maeda ◽  
Masashi Ando ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Intracellular Signaling ◽  
Immunoglobulin E ◽  
Inhibitory Effect ◽  
Biologically Active ◽  
Type I ◽  
Dependent Manner ◽  
Echinochrome A ◽  
Basophilic Leukemia ◽  
Anthocidaris Crassispina

Echinochrome A (Echi-A) was isolated from the sea urchin Anthocidaris crassispina and its structure determined using 1D and 2D-NMR. In the present study, we examined the inhibitory effect of Echi-A on antigen-stimulated degranulation in rat basophilic leukemia RBL-2H3 cells, which were suppressed in a dose dependent manner. The antigens bind to the high affinity immunoglobulin E receptor, which is expressed on the surface of mast cells and basophils and activate intracellular signal transduction, resulting in the release of biologically active mediators such as histamine. In order to disclose the inhibitory mechanisms of degranulation by Echi-A, we examined the elevation in intracellular Ca2+ concentration ([Ca2+]i), production levels of intracellular reactive oxygen species (ROS) and early intracellular signaling events. Both elevation of [Ca2+]i and intracellular ROS production were markedly suppressed in cells treated with Echi-A. Echi-A also suppressed the activation of Lyn, Syk, and PLCγ1/2 in antigen-stimulated cells. These results indicated that inhibition of antigen-stimulated degranulation in RBL-2H3 cells by Echi-A is mainly due to the inactivation of Lyn/Syk/PLCγ signaling pathways. Our findings suggest that Echi-A could be a beneficial agent for alleviating the symptoms of type I allergy.

A comparison of the effects of acute verses chronic administration of phenoxybenzamine on pressor responses elicited by the selective α1-adrenoceptor agonist cirazoline in the pithed rat preparation

1992 ◽  
Vol 70 (6) ◽  
pp. 916-921 ◽  
Author(s):  
Reza Tabrizchi ◽  
Christopher R. Triggle
Keyword(s):  
Pressor Response ◽  
Chronic Administration ◽  
Inhibitory Effect ◽  
Acute Administration ◽  
Dependent Manner ◽  
Pithed Rat ◽  
Inhibitory Effects ◽  
Receptor Reserve ◽  
Pressor Responses ◽  
The Right

The effects of nifedipine on the pressor responses to cirazoline were examined in the pithed rat preparation that had received either acute or chronic phenoxybenzamine treatment. Phenoxybenzamine was administered, i.v., to conscious rats, either acutely at 0.01, 0.03, and 0.1 mg/kg, 60 min prior to the commencement of the experiments or chronically at 0.1, 0.3, and 1.0 mg/kg, once daily for 7 days. Nifedipine was administered i.a. (1.0 mg/kg) after the animals had been pithed. The acute or chronic administration of phenoxybenzamine alone displaced the dose–response curve to cirazoline to the right in a dose-dependent manner, while reducing the slope function and maximum response to the agonist. The combined effects of acute phenoxybenzamine and nifedipine produced an additive inhibitory effect on the pressor response elicited by cirazoline, which was most apparent following the removal of receptor reserve by acute phenoxybenzamine. The inhibitory effects of nifedipine and chronically administered phenoxybenzamine were additive at the lower administered doses of the alkylating agent but, in contrast with the effects of acute phenoxybenzamine, the enhanced inhibitory effects of nifedipine were reduced following the removal of receptor reserve. These results indicate that the chronic administration of phenoxybenzamine reduces the additive inhibitory effects of nifedipine and phenoxybenzamine that were observed following the acute administration of phenoxybenzamine.Key words: α1-adrenoceptors, vasoconstriction, subtypes, pithed rat, calcium channel antagonist.

A Comparative Study of the Effects of Adrenoceptor Antagonists on Platelet Aggregation and Thromboxane Generation

1985 ◽  
Vol 54 (02) ◽  
pp. 480-484 ◽  
Author(s):  
I A Greer ◽  
J J Walker ◽  
M McLaren ◽  
A A Calder ◽  
C D Forbes
Keyword(s):  
Platelet Aggregation ◽  
Vascular Disease ◽  
Platelet Rich Plasma ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Wide Range ◽  
The Right

SummaryPlatelet aggregation and thromboxane A2 have been implicated in the pathogenesis of several forms of vascular disease. The aim of this study was to determine the effect of a wide range of adrenoceptor antagonists on platelet aggregation, and thromboxane A2 production, from normal human platelet rich plasma in vitro. Labetalol, pindolol and propranolol inhibited platelet aggregation to collagen in a dose dependent manner. Increasing the concentration of collagen “shifted” the dose response curve to the right. These 3 drugs also significantly inhibited thromboxane A2 generation in response to collagen but not to arachidonic acid. This effect was independent of any inhibitory effect of these drugs on platelet aggregation, and occurred at a drug concentration close to that obtained in vivo. Atenolol, metoprolol, prazosin and timolol were similarly assessed but had no effect on either platelet aggregation or thromboxane A2 generation. This ability of labetalol, pindolol, and propranolol to inhibit platelet aggregation and thromboxane generation, may be of clinical benefit in view of the increasing evidence implicating thromboxane A2 in the pathogenesis of vascular disease.

What is a juvenile sea urchin? A comparative and phylogenetic survey of post-metamorphic juveniles

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S44-S45
Author(s):  
Richard B. Emlet
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Trait Variation ◽  
Adult Form ◽  
Additional Information ◽  
Larval Stages ◽  
Classical Studies ◽  
Phylotypic Stage ◽  
Taxonomic Range ◽  
Test Shape

Echinoid development progresses through embryonic and larval stages to metamorphosis and the adult form. Despite vast differences in embryos and larval forms, including bilaterally symmetric echinopluteus larvae, ovoid non-feeding larvae and brooded embryos, all metamorphose into juvenile sea urchins with pentaradial symmetry. The adult sea urchin body plan is initiated as the juvenile rudiment. The rudiment has been called the phylotypic stage for the class Echinoidea, a designation that implies little variation at this midpoint in development (e.g. Raff et al., 1991; Richardson, 1995; Raff, 1996). However, right at metamorphosis (upon eversion of the juvenile rudiment), variations in test symmetry, shape and number of spines, and number of skeletal plates, podia and pedicellariae are present in juveniles. This variation suggests either that there is no phylotypic stage or that such a stage occurs earlier in rudiment formation. To distinguish between these possibilities, I explored the patterns by which the juvenile rudiment is formed as well as the variation among juveniles approximately 1 day after metamorphosis in 19 echinoid taxa covering a broad taxonomic range including cidaroids, diadematids, irregular echinoids (spatangoids and clypeasteroids), arbaciids, temnopleurids, echinometrids and strongylocentrotids. Most of the material for analysis of juveniles was obtained by the author. Additional information was gathered from classical studies of metamorphosis. Data were collected on the number and shape of dorsal pedicellariae, juvenile and adult spines, primary and secondary podia, and juvenile test shape. When possible multiple individuals within a species were examined, revealing no or only minor trait variation. These data were mapped on a well-resolved phylogeny established from adult characters.

Distribution of apoptosis-like cells in sea urchin early embryogenesis

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S76-S76 ◽  
Author(s):  
Hazime Mizoguchi ◽  
Dai Kudo ◽  
Yumi Shimizu ◽  
Keiko Hirota ◽  
Shinobu Kawai ◽  
...  
Keyword(s):  
Comet Assay ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Early Embryogenesis ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Gastrula Stage ◽  
Tunel Method ◽  
Dapi Staining ◽  
Pluteus Stage ◽  
Number Of Cells

It has been reported that the number of cells per embryo increases from the cleavage stage to the pluteus stage. Also, it has been reported that the number of cells per embryo from the early gastrula stage to the mid-gastrula stage increases very slightly (Mizoguchi, 1999). A detailed analysis of cell proliferation during this period would thus seem to be necessary.On the other hand, Roccheri et al. (1997) reported spontaneous apoptosis at the early pluteus stage, especially in the regions of arm and intestine. However, it is unknown whether apoptosis occurs before the pluteus stage.Using the Tumor, Neuro and/or Cardio TACS in situ apoptosis detection kit (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling: TUNEL method, Trevigen, USA), the Comet assay kit (Trevigen, USA) and DAPI (4,6-diamidino-2-phenylinodole dihydrochloride) staining, we investigated the distribution of apoptosis-like cells in sea urchins during early embryogenesis to clarify the relationship between cell death and morphogenesis.The embryos of the sea urchin Hemicentrotus pulcherrimus were used in the present study. Three methods of detection of apoptosis signals in the embryos were performed: (1) defects in chromosomes and punctured nuclear envelopes of cells were detected by DAPI staining; (2) apoptosis-like cells were stained a brown colour by the TUNEL method; (3) some clear tails which detected the fragmentation of DNA were found by the Comet assay. These signals indicate apoptosis-like cells.

scholarly journals Chemosensitivity in the Sea Urchin Paracentrotus lividus (Echinodermata: Echinoidea) to Food-Related Compounds: An Innovative Behavioral Bioassay

2021 ◽  
Vol 9 ◽  
Author(s):  
Paolo Solari ◽  
Viviana Pasquini ◽  
Marco Secci ◽  
Angelica Giglioli ◽  
Roberto Crnjar ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Paracentrotus Lividus ◽  
Arthrospira Platensis ◽  
Point Of View ◽  
Dependent Manner ◽  
Chemical Sensitivity ◽  
Blue Green Algae ◽  
Related Compounds

Like other animals, echinoderms rely on chemical senses to detect and localize food resources. Here, we evaluate the chemical sensitivity of the sea urchin Paracentrotus lividus to a number of stimuli possibly related to food, such as a few sugars, compared to the blue-green algae Spirulina (Arthrospira platensis). To do this we developed a simple, innovative method based on the recording of “urchinograms” estimating the movements of spines, pedicellariae, tube feet, and eventually of the whole sea urchin, in response to chemicals, while keeping both the whole animal and the stimulus in their natural environment, underwater. Our results show that Spirulina is a highly stimulating compound for the sea urchin, by acting in a dose-dependent manner. The animals resulted also sensitive, even if to a lesser extent, to some sugars, such as the monosaccharide glucose, but not to its isomer fructose, while among disaccharides, they sensed cellobiose, but not sucrose or trehalose. From an applied point of view, any insight into the chemical sensitivity of sea urchins toward potential food-related compounds may lead to the discovery of key chemicals that would help improve the efficiency and reduce the costs of dietary substrates for optimization of intensive rearing strategies. Although this method has been developed for P. lividus, it will be suitable to evaluate the chemical sensitivity of other echinoderms and other marine invertebrates characterized by low mobility.

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