Activation of extracellular signal-regulated kinases during dehydration in the African clawed frog, <i>Xenopus laevis</i>
Bibliographic record
Abstract
In its native environment the African clawed frog, Xenopus laevis, can experience seasonally arid conditions that impose dehydration stress. Activation of intracellular signal transduction cascades can mediate and coordinate biochemical responses to ameliorate dehydration stress. This study examines the extracellular signal-regulated kinase (ERK) signaling cascade, analyzing responses of both upstream and downstream components in six tissues of X. laevis experiencing medium and high levels of dehydration, 16.6+/-1.59 and 28.0+/-1.6% of total body water lost, respectively. Immunoblotting was used to assess the three tiers in this mitogen-activated protein kinase (MAPK) cascade: the initiating MAPK kinase kinases (c-Raf, MEKK), the MAPK kinase (MEK1/2), and finally the MAPK (ERK1/2). The amount of active phosphorylated c-Raf(Ser338) rose by 2- to 2.5-fold under high dehydration in muscle, lung and skin whereas MEKK protein levels rose in these organs and also increased 4-fold in liver. As a result, phosphorylated active MEK1/2(Ser217/221) increased significantly by 2- to 6-fold during dehydration which, in turn, led to 2- to 6-fold increases in phospho-ERK(Thr202/Tyr204) content in all tissues except skin. Given this clear demonstration of ERK cascade activation, two downstream targets of ERK2 were then evaluated. The amount of phosphorylated active transcription factor, STAT3(Ser727) and p90 ribosomal S6 kinase (RSK(Ser380)) increased particularly in muscle, lung and kidney. Furthermore, RSK activation was correlated with a 5- to 8-fold increase in phosphorylation of its target, S6 ribosomal protein. Overall, the results show a strong conserved activation of the ERK cascade in X. laevis tissues in response to dehydration.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".