Sarco/Endoplasmic Reticulum Ca2+‐ATPase 2 (SERCA2) is Present at Tubulobulbar Complexes
Bibliographic record
Abstract
Endocytic structures known as tubulobulbar complexes (TBCs) internalize intact intercellular junction proteins at sites of intercellular attachment between spermatids and Sertoli cells prior to sperm release. TBCs are highly specialized clathrin‐based endocytosis machines. They also resemble podosomes which have an elongated membrane tube and an associated dendritic actin network. However, unlike podosomes that have a membrane core of a single plasma membrane, the core of TBCs consists of two plasma membranes: the membrane of the Sertoli cell which the structure is invaginated into and the membrane of a spermatid. TBCs have a bulb region in the distal third part of the complex which does not have the cuff of actin but is closely associated with a cisterna of endoplasmic reticulum (ER). We hypothesize that the plasma membrane/ER junction is involved in Ca 2+ signaling. If this is true then we would expect to find molecular machinery involved in calcium signaling mechanisms in other systems. In this study, we used immunofluorescence to probe for the calcium pump, sarco/endoplasmic reticulum Ca 2+ ‐ATPase 2 (SERCA2), which pumps Ca 2+ into the ER. Cryosections and epithelial fragments from perfusion‐fixed rat testes were probed with antibodies against SERCA2 and an appropriate fluorescent secondary antibody. The SERCA2 antibody has a labeling pattern that extends from the base of the epithelium to the apex which is consistent with a Sertoli cell pattern. As seen in both epithelial fragments and cryosections, the SERCA2 antibody labels regions where we would expect TBCs to be. Our results show that one possible component of a calcium signaling mechanism is present in regions containing TBCs. Support or Funding Information Supported by the Natural Sciences and Engineering Research Council of Canada Discovery Grants program.
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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".