Characterization of the «Smpec» Knock-out mouse
Bibliographic record
Abstract
The Smpec gene is expressed solely in the chondrocytes at the resting and proliferating zones but not in the hypertrophic chondrocytes. The SMPEC protein is a chondroitin sulfate proteoglycan (CS PG) composed of 121 amino acids. In silico analysis suggests it is a transmembrane protein. The purpose of this study was to characterize the Smpec knockout (KO) mouse and identify its role in skeletogenesis in vivo. To confirm the suggested topology for the SMPEC protein, immunofluorescence (IF) was performed on 4 days post natal (P4) distal femur. The protein was localized to the cell surface of resting and proliferating chondrocytes, but also accumulated in intercolumnar septum of hypertrophic chondrocytes, suggesting its shed. Alcian blue /alizarin red staining, which stains cartilage and bone respectively, was performed on arms of P4 wild-type (WT) and KO mice and there were no qualitative differences in staining intensity neither in bone nor in cartilage of KO compared to WT. However, quantitative measurement indicated that the humeri were all statistically reduced in length by 10.4% in the KO compared to the WT. As it is wellknown that the longitudinal growth of long bones is mediated through the growth plate, thereby we focused our study on this region. Safranin O/Fast green staining in P4 distal femur revealed that the chondrocyte cell density of the resting and proliferating zones appeared less in the KO than in WT littermates. Quantitative analysis confirmed the hypocellularity of these zones. However, the thickness of the hypertrophic zone was normal. The expression profile of genes known to be important in skeletogenesis and mineralization was assessed by real-time qPCR. No statistically significant changes were detected in the Smpec KO as compared to WT at the three ages analyzed (day 4, day 28 and12 months). Similarly, primary chondrocytes cultures established from KO and WT rib cages, did not present any significant changes in expression of Col2a1, Col10a1, Sox9, and Acan. Furthermore, in such cultures, extracellular matrix deposition of proteoglycanaggrecan as assessed by alcian blue staining, was not significantly altered, indicating similarity in the metabolic activity of the chondrocytes. This indicates for the first time that loss of Smpec results in mild dwarfism in mice and that its function cannot be compensated by other genes at least at neonatal ages. The mechanism by which the lack of SMPEC causes dwarfism is still unclear.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.007 | 0.003 |
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".