montanabay
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<a href=showthread.php?s=&postid=12672559#post12672559 target=_blank>Originally posted</a> by Skeptic_07
so, corals are like people in that they dont make thier own vitamin C and have to absorb it from the water like humans who must ingest it.
is that right? :lol:
Are suggesting that because they naturally produce it, they couldnââ"šÂ¬Ã¢"žÂ¢t benefit from supplementation? Iââ"šÂ¬Ã¢"žÂ¢m confused why this so funnyââ"šÂ¬Ã‚¦
I did reduce my light time, but saw no results<a href=showthread.php?s=&postid=12672559#post12672559 target=_blank>Originally posted</a> by Skeptic_07
If too much light causes overactive zooxanthellae resulting in oxidative stress. the solution seems very simple to me since we are the ones who control the lights on our tanks. :lol:
<a href=showthread.php?s=&postid=12672559#post12672559 target=_blank>Originally posted</a> by Skeptic_07
what else you got?
If it wasnââ"šÂ¬Ã¢"žÂ¢t for your antagonizing I probably wouldnââ"šÂ¬Ã¢"žÂ¢t have done a lit review this farââ"šÂ¬Ã‚¦but, its actually interesting stuff and this article seems to support my theory. For those who just want the gist of the article, read the bold red at the end.
Cheers,
Josh
http://ir.lib.u-ryukyu.ac.jp/bitstream/123456789/794/1/2005PG-18.pdf
PG-18 Preliminary studies on the bleaching mechanism using coral cell aggregates
Badrun Nesa and Michio Hidaka
Department of Chemistry, Biology and Marine Science
University of the Ryukyus, Nishihara, Okinawa 903-0213
INTRODUCTION
To investigate bleaching mechanisms of coral-zooxanthella symbiotic systems, it is important to study response of corals to stress conditions at cellular or tissue level. We attempted to establish an experimental system to study response of coral cells to stress treatment and chemical reagents such as antioxidant. Dissociated coral cells aggregate to form spherical bodies, which start to rotate by ciliary movement. These spherical bodies (tissue balls) stop their rotation and become disintegrated when exposed to stress. The first objective of our study is to evaluate the use of tissue balls for bleaching studies. The second objective is to test the hypothesis that zooxanthellae produce harmful substances such as active oxygen when exposed to high temperature under light.
MATERIALS AND METHODS
We exposed tissue balls containing various numbers of zooxanthellae to high temperature and examined the relationship between the zooxanthella density and survival time of the tissue balls. Tissue balls were prepared from dissociated cells of Fungia sp. Dissociated cells were allowed to form cell aggregates (tissue balls) in a petridish for one night. Tissue balls of similar size were put in each well of a 96 multi-well plate containing 300 ul FSW and allowed to recover overnight. The volume of tissue balls was estimated from video print assuming that they are ellipsoid. Tissue balls were then exposed to thermal stress (31Ã"šÃ‚°C) or control condition (25Ã"šÃ‚°C). Tissue balls were observed at 2-6 h intervals during the daytime until all the tissue balls died. In some cases, antioxidants (125 uM ascorbic acid and 250 Uml-1 catalase) were added during high temperature treatment. Tissue balls were scored as healthy, stopped, or degraded at each observation to make survival curves under high and normal temperature conditions. After the tissue balls disintegrated, the number of zooxanthellae within each tissue ball was counted to calculate zooxanthella densities of the tissue balls.
RESULTS AND DISCUSSION
Survival curves of tissue balls were markedly different between 31 and 25Ã"šÃ‚°C. At 31Ã"šÃ‚°C tissue balls, died more quickly than those kept at 25Ã"šÃ‚°C. Addition of antioxidants extended the survival time of tissue balls at 31Ã"šÃ‚°C. There was a negative correlation between the survival time and zooxanthella density of tissue balls at 31Ã"šÃ‚°C, while no significant correlation between survival time and zooxanthellae density was found at 25Ã"šÃ‚°C or at 31 Ã"šÃ‚°C in the presence of the antioxidants. There was no significant correlation between the survival time and the size of tissue balls at both temperatures. The present results showed that the higher the zooxanthellae density was the more quickly the tissue balls died and supported our hypothesis that zooxanthellae produce harmful substances and cause damage to coral cells under stressful condition.The finding that the antioxidants extended the survival time of tissue balls at high temperature suggests that zooxanthellae produce active oxygen species under the stress condition. This study also showed that tissue balls provide us a good experimental system to study the effect of stress condition and various chemical reagents on corals cells.
Key words: coral, bleaching, active oxygen, zooxanthellae, symbiosis
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