scholarly journals The Flavor Enhancer Maltol Increases Pigment Aggregation in Dermal and Neural Melanophores in Xenopus laevis Tadpoles

2019 ◽  
Vol 39 (2) ◽  
pp. 381-395
Author(s):  
Lara I. Dahora ◽  
Ashley Fitzgerald ◽  
Matthew Emanuel ◽  
Alexa F. Baiges ◽  
Zahabiya Husain ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Pigment Aggregation ◽  
Flavor Enhancer

scholarly journals “The flavor enhancer maltol increases pigment aggregation in dermal and neural melanophores in Xenopus laevis tadpoles”

2019 ◽  
Author(s):  
Lara I. Dahora ◽  
Ashley Fitzgerald ◽  
Matthew Emanuel ◽  
Alexa F. Baiges ◽  
Zahabiya Husain ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Time Course ◽  
Dependent Manner ◽  
Adaptation Mechanism ◽  
Toxicological Effect ◽  
Similar Dose ◽  
Dynamic Cell ◽  
Pigment Aggregation ◽  
Dose Dependent ◽  
Flavor Enhancer

ABSTRACTMelanophores are pigmented cells that change the distribution of pigmented melanosomes, enabling animals to appear lighter or darker for camouflage, thermoregulation, and UV-protection. A complex series of hormonal and neural mechanisms regulates melanophore pigment distribution, making these cells a valuable tool to screen toxicants as a dynamic cell type that responds rapidly to the environment. We found that maltol, a naturally occurring flavor enhancer and fragrance agent, induces melanophore pigment aggregation in a dose-dependent manner in Xenopus laevis tadpoles. To determine if maltol affects camouflage adaptation, we placed tadpoles into maltol baths situated over either white or black background. Maltol induced pigment aggregation in a similar dose-dependent pattern regardless of background color. We also tested how maltol treatment compares to melatonin treatment and found that the degree of pigment aggregation induced by maltol is similar to treatment with melatonin, but the time course differs significantly. Last, maltol had no effect on mRNA expression of pro-opiomelanocortin or melanin concentrating hormone receptor in the brain, both of which regulate camouflage-related pigment aggregation. Our results suggest that maltol does not exert its effects via the camouflage adaptation mechanism nor via melatonin-based mechanisms. These results are the first to identify a specific toxicological effect of maltol exposure and rules out several mechanisms by which maltol may exert its effects on pigment aggregation.

scholarly journals Protein kinase C activation antagonizes melatonin-induced pigment aggregation in Xenopus laevis melanophores.

1992 ◽  
Vol 119 (6) ◽  
pp. 1515-1521 ◽  
Author(s):  
D Sugden ◽  
S J Rowe
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Xenopus Laevis ◽  
Pigment Granule ◽  
Melatonin Receptors ◽  
Kinase C ◽  
Pigment Granules ◽  
Slow Aggregation ◽  
Pigment Aggregation ◽  
Induced Aggregation

The pineal hormone, melatonin (5-methoxy N-acetyltryptamine) induces a rapid aggregation of melanin-containing pigment granules in isolated melanophores of Xenopus laevis. Treatment of melanophores with activators of protein kinase C (PKC), including phorbol esters, mezerein and a synthetic diacylglycerol, did not affect pigment granule distribution but did prevent and reverse melatonin-induced pigment aggregation. This effect was blocked by an inhibitor of PKC, Ro 31-8220. The inhibitory effect was not a direct effect on melatonin receptors, per se, as the slow aggregation induced by a high concentration of an inhibitor of cyclic AMP-dependent protein kinase (PKA), adenosine 3',5'-cyclic monophosphothioate, Rp-diastereomer (Rp-cAMPS), was also reversed by PKC activation. Presumably activation of PKC, like PKA activation, stimulates the intracellular machinery involved in the centrifugal translocation of pigment granules along microtubules. alpha-Melanocyte stimulating hormone (alpha-MSH), like PKC activators, overcame melatonin-induced aggregation but this response was not blocked by the PKC inhibitor, Ro 31-8220. This data indicates that centrifugal translocation (dispersion) of pigment granules in Xenopus melanophores can be triggered by activation of either PKA, as occurs after alpha-MSH treatment, or PKC. The very slow aggregation in response to inhibition of PKA with high concentrations of Rp-cAMPS, suggests that the rapid aggregation in response to melatonin may involve multiple intracellular signals in addition to the documented Gi-mediated inhibition of adenylate cyclase.

THE ROLE OF ADENOSINE 3′,5′-CYCLIC MONOPHOSPHATE AND CATECHOLAMINES IN THE PIGMENT MIGRATION PROCESS IN XENOPUS LAEVIS

1970 ◽  
Vol 64 (2) ◽  
pp. 364-376 ◽  
Author(s):  
F. C. G. van de Veerdonk ◽  
Th. M. Konijn
Keyword(s):  
Xenopus Laevis ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Pigment Dispersion ◽  
Migration Process ◽  
Receptor Blocking ◽  
Mediating Role ◽  
Pigment Migration ◽  
Pigment Aggregation

ABSTRACT The mediating role of 3,5-AMP in the MSH induced pigment dispersion, is demonstrated in several ways. The amount of 3,5-AMP in darkened skins is about twice the amount present in lightened skins. Inhibition of 3,5-AMP degradation by theophylline results in a dispersion of the pigment granules. Inhibition of 3,5-AMP synthesis by acetylcholine prevents dispersion of the granules in the presence of MSH. In Xenopus laevis the dispersion reaction is stimulated by catecholamines. This stimulation is brought about by adrenergic receptors. Using adrenergic receptor blocking agents, some insight in the stimulation has been obtained in larval as well as in adult animals. Finally, an attempt has been made to explain the pigment aggregation by an intensified breakdown of 3,5-AMP by the enzyme phosphodiesterase.

Height Changes Associated with Pigment Aggregation in Xenopus laevis Melanophores

2004 ◽  
Vol 24 (3) ◽  
pp. 203-214
Author(s):  
Charlotte Immerstrand ◽  
Harriet M. Nilsson ◽  
Margaretha Lindroth ◽  
Tommy Sundqvist ◽  
Karl-Eric Magnusson ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Xenopus Laevis ◽  
Leading Edge ◽  
Pigment Cells ◽  
Cell Height ◽  
Lower Vertebrates ◽  
Brownish Black ◽  
Height Increase ◽  
Pigment Aggregation ◽  
Cell Centre

Melanophores are pigment cells found in the skin of lower vertebrates. The brownish-black pigment melanin is stored in organelles called melanosomes. In response to different stimuli, the cells can redistribute the melanosomes, and thereby change colour. During melanosome aggregation, a height increase has been observed in fish and frog melanophores across the cell centre. The mechanism by which the cell increases its height is unknown. Changes in cell shape can alter the electrical properties of the cell, and thereby be detected in impedance measurements. We have in earlier studies of Xenopus laevis melanophores shown that pigment aggregation can be revealed as impedance changes, and therefore we were interested in investigating the height changes associated with pigment aggregation further. Accordingly, we quantified the changes in cell height by performing vertical sectioning with confocal microscopy. In analogy with theories explaining the leading edge of migrating cells, we investigated the possibility that the elevation of plasma membrane is caused by local swelling due to influx of water through HgC12-sensitive aquaporins. We also measured the height of the microtubule structures to assess whether they are involved in the height increase. Our results show that pigment aggregation in X. laevis melanophores resulted in a significant height increase, which was substantially larger when aggregation was induced by latrunculin than with melatonin. Moreover, the elevation of the plasma membrane did not correlate with influx of water through aquaporins or formation of new microtubules, Rather, the accumulation of granules seemed to drive the change in cell height.

Androgen-induced plasticity at a “vocal” neuromuscular synapse

1994 ◽  
Vol 52 ◽  
pp. 32-33
Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman
Keyword(s):  
Xenopus Laevis ◽  
Motor Neurons ◽  
Sexual Differentiation ◽  
Molecular Basis ◽  
Neuromuscular Synapse ◽  
Sexually Dimorphic ◽  
Intracellular Protein ◽  
Developmental Program ◽  
Androgen Action ◽  
Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

PENGETAHUAN PENGGUNAAN MONOSODIUM GLUTAMATE (MSG) IBU RUMAH TANGGA

2018 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Siti Nur Rochimiwati ◽  
Sukmawati Sukmawati ◽  
Budiman Budiman
Keyword(s):  
Health Hazard ◽  
Monosodium Glutamate ◽  
Food Additives ◽  
Descriptive Study ◽  
Interview Method ◽  
Level Of Knowledge ◽  
Lower Intelligence ◽  
Use Of Knowledge ◽  
Health Objective ◽  
Flavor Enhancer

Background : flavor enhancing food additives are often added as a flavor enhancer known as MSG that exceed the dose . if the addition of the additive is often done to cause dependence , so it will pose a health hazard to the consumer , such as stomach disorders, allergies , hypertension , asthma , cancer , diabetes , and lower intelligence. Most housewives do not know the information would adversely affect health. Objective : This study aims to describe the level of knowledge of the use of monosodium glutamate ( MSG ) housewife in backwoods village sauleya timbuseng Polongbangkeng northern districts Kab.Takalar. Methods : This is a descriptive study. samples are all housewives in the hamlet village sauleya timbuseng Polongbangkeng northern districts Kab. Takalar , who meet the criteria as much as 49 people . Data on the use MSG knowledge samples obtained by the interview method which uses a questionnaire instrument.the data presented in the from of frequency distribution graphic and narrative. Result : Results of research on the use of knowledge MSG housewives generally less category as many as 25 ( 51.0 % ) , use of MSG housewives generally can not be tolerated as many as 36 ( 73.5 % ). Conclusion : Knowledge of the use of MSG housewife classified as less and use MSG can not be tolerated.

THE EFFECT OF THE SKIN SECRETION OF XENOPUS LAEVIS ON ITS DERMAL MELANOPHORES

1956 ◽  
Vol 23 (3) ◽  
pp. 265-273 ◽  
Author(s):  
A. C. J. Burgers ◽  
G. J. van Oordt
Keyword(s):  
Xenopus Laevis ◽  
Skin Secretion
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