Identification, evolution and expression of three olfactory gene families in Atlantic salmon (Salmo salar)
Bibliographic record
Abstract
It has been hypothesized that salmonids use olfactory cues to return to their natal rivers and streams. However, the key components of the molecular pathway involved in imprinting and homing are still unknown. If odorants are involved in salmon homing migration then olfactory receptors should play a critical role in the dissipation of information from the environment to the fish. To understand the molecular basis for imprinting and homing in Atlantic salmon (Salmo salar), it is important to identify and characterize the olfactory receptors in the Atlantic salmon genome. Aquatic chemical cues are received through the salmon nares and into the nasal cavity that contains a single olfactory organ, olfactory rosette. The olfactory rosette contains sensory neurons, which are thought to express only one olfactory receptor. In this study, three major superfamilies of fish olfactory receptors (MOR, ora and OlfC) were examined. To identify the olfactory genes in Atlantic salmon several genomic and bioinformatic techniques were used. First, an Atlantic salmon bacterial artificial chromosome (BAC) library was screened with probes designed from previously identified fish olfactory receptor sequences. Then a selected number of hybridization positive BACs containing olfactory receptors were shotgun cloned and sequenced. From these BAC sequences, two ora genes and 55 OlfC genes were identified in Atlantic salmon. The second technique used to identify olfactory receptors in Atlantic salmon was a bioinformatic approach that involved screening a 3-fold Atlantic salmon genome sequence for olfactory receptors. Using this approach, 24 MOR and the remaining five ora genes were identified, as well as another 24 partial genes or pseudogenes. As a first step to understand how olfactory receptors are involved in imprinting and homing, a suite of olfactory receptors were selected to examine the expression profiles of these genes across different life stages and life histories of wild Atlantic salmon from Newfoundland, Canada. Seven differentially expressed OlfC genes were identified in juvenile anadromous salmon compared to returning adult salmon. From this research, I hypothesize that OlfC genes may play an important role in the imprinting of home stream water olfactory cues in anadromous Atlantic salmon.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".