Localization of a Female-Specific Marker on the Chromosomes of the Brown Seaweed Saccharina japonica Using Fluorescence In Situ Hybridization
Bibliographic record
Abstract
BACKGROUND: There is a heteromorphic alternative life in the brown seaweed, Saccharina japonica (Aresch.) C. E. Lane, C. Mayes et G. W. Saunders ( = Laminaria japonica Aresch.), with macroscopic monoecious sporophytes and microscopic diecious gametophytes. Female gametophytes are genetically different from males. It is very difficult to identify the parent of a sporophyte using only routine cytological techniques due to homomorphic chromosomes. A sex-specific marker is one of the best ways to make this determination. METHODOLOGY/PRINCIPAL FINDINGS: To obtain clear images, chromosome preparation was improved using maceration enzymes and fluorochrome 4', 6-diamidino-2-phenylindole (DAPI). The chromosome number of both male and female haploid gametophytes was 31, and there were 62 chromosomes in diploid sporophytes. Although the female chromosomes ranged from 0.77 µm to 2.61 µm in size and were larger than the corresponding ones in the males (from 0.57 µm to 2.16 µm), there was not a very large X chromosome in the females. Based on the known female-related FRML-494 marker, co-electrophoresis and Southern blot profiles demonstrated that it was inheritable and specific to female gametophytes. Using modified fluorescence in situ hybridization (FISH), this marker could be localized on one unique chromosome of the female gametophytes as well as the sporophytes, whereas no hybridization signal was detected in the male gametophytes. CONCLUSIONS/SIGNIFICANCE: Our data suggest that this marker was a female chromosome-specific DNA sequence. This is the first report of molecular marker localization on algal chromosomes. This research provides evidence for the benefit of using FISH for identifying molecular markers for sex identification, isolation of specific genes linked to this marker in the females, and sex determination of S. japonica gametophytes in the future.
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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 | 0.000 | 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) | 0.002 | 0.001 |
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".