Molecular mechanism of nutrient uptake in developing embryos of oviparous cloudy catshark (Scyliorhinus torazame)
Bibliographic record
Abstract
Forms of embryonic nutrition are highly diverse in cartilaginous fishes, which contain oviparity, yolk-sac viviparity and several types of matrotrophic viviparity (histotrophy, oophagy, and placentotrophy). The molecular mechanisms of embryonic nutrition are poorly understood in these animals as few species are capable of reproducing in captivity. Oviparous cartilaginous fishes solely depend on yolk nutrients for their growth and development. In the present study, we compared the contribution to embryonic nutrition of the embryonic intestine with the yolk sac membrane (YSM). RNA-seq analysis was performed on the embryonic intestine and YSM of the oviparous cloudy catshark Scyliorhinus torazame to identify candidate genes involved in nutrient metabolism to further the understanding of nutrient utilization of developing embryos. RNA-seq discovery was subsequently confirmed by quantitative PCR analysis and we identified increases in several amino acid transporter genes (slc3a1, slc6a19, slc3a2, slc7a7) as well as genes involved in lipid absorption (apob and mtp) in the intestine after 'pre-hatching', which is a developmental event marked by an early opening of the egg case about 4 months before hatching. Although a reciprocal decrease in the nutritional role of YSM was expected after the intestine became functional, we observed similar increases in gene expression among amino acid transporters, lipid absorption molecules, and lysosomal cathepsins in the extraembryonic YSM in late developmental stages. Ultrastructure of the endodermal cells of YSM showed that yolk granules were incorporated by endocytosis, and the number of granules increased during development. Furthermore, the digestion of yolk granules in the YSM and nutrient transport through the basolateral membrane of the endodermal cells appeared to be enhanced after pre-hatching. These findings suggest that nutrient digestion and absorption is highly activated in both intestine and YSM after pre-hatching in catshark embryos, which supports the rapid growth at late developmental stages.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 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".