The developmental origin and compartmentalization of glutathione-s-transferase omega 2 isoforms in the perinuclear theca of eutherian spermatozoa†
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Bibliographic record
Abstract
The perinuclear theca (PT) is a condensed, nonionic detergent resistant cytosolic protein layer encapsulating the sperm head nucleus. It can be divided into two regions: the subacrosomal layer, whose proteins are involved in acrosomal assembly during spermiogenesis, and the postacrosomal sheath (PAS), whose proteins are implicated in sperm-oocyte interactions during fertilization. In continuation of our proteomic analysis of the PT, we have isolated two prominent PT-derived proteins of 28 and 31 kDa from demembranated bovine sperm head fractions. These proteins were identified by mass spectrometry as isoforms of glutathione-s-transferase omega 2 (GSTO2). Immunoblots probed with anti-GSTO2 antibodies confirmed the presence of the GSTO2 isoforms in these fractions while fluorescent immunocytochemistry localized the isoforms to the PAS region of the bull, boar, and murid PT. In addition to the PAS labeling of GSTO2, the performatorium of murid spermatozoa was also labeled. Immunohistochemistry of rat testes revealed that GSTO2 was expressed in the third phase of spermatogenesis (i.e., spermiogenesis) and assembled in the PAS and perforatorial regions of late elongating spermatids. Fluorescent immunocytochemistry performed on murine testis cells co-localized GSTO2 and tubulin on the transient microtubular-manchette of elongating spermatids. These findings imply that GSTO2 is transported and deposited in the PAS region by the manchette, conforming to the pattern of assembly found with other PAS proteins. The late assembly of GSTO2 and its localization in the PAS suggests a role in regulating the oxidative and reductive state of covalently linked spermatid/sperm proteins, especially during the disassembly of the sperm accessory structures after fertilization.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 it