Toxic effects of <i>Heterosigma akashiw</i>o do not appear to be mediated by hydrogen peroxide
Bibliographic record
Abstract
The ichthyotoxic red tide organism Heterosigma akashiwo (Raphidophyceae) has been associated with fish kill events within the aquaculture industry for many years. The precise toxicological mechanism involved in these fish kills is unclear; however, much research attention has focused on the production of reactive oxygen species (ROS) by these toxic algae. In this study, we investigated the production of hydrogen peroxide (H 2 O 2 ) by isolates of H. akashiwo and the nontoxic chlorophyte Tetraselmis apiculata . Subsequently, we tested those concentrations of H2O2 on vertebrate cell lines and the invertebrate Artemia salina (brine shrimp) to investigate mortality. Net production rates for the H. akashiwo isolates ranged from 0.46 to 7.89 pmol H 2 O 2 min −1 (10 4 cells) −1 while obtaining maximum concentrations between 0.14 and 0.91 µM H 2 O 2 . Conversely, T. apiculata produced only 0.03 pmol H 2 O 2 min ±1 (10 4 cells with a maximum level on 0.04 µM. However, toxic effects on UMRߚ106 and HEKߚ293 cells were only induced by acute and protracted exposure to concentrations of H 2 O 2 >= 0.1 mM. Additionally, significant mortality of A. salina in the presence or absence of ferric and ferrous iron was induced by H 2 O 2 levels >= 1 mM. Iron is a redox metal that reduces H 2 O 2 to hydroxy radicals. These data collectively indicate that production of H 2 O 2 by multiple isolates of H. akashiwo is orders of magnitude less than that required for mortality of either the vertebrate cell lines or the invertebrate A. salina . Other nonichthyotoxic roles for extracellular ROS are proposed.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".