Bibliographic record
Abstract
Spermatogenesis is a complex process of male germ cell development in which the diploid spermatogonia undergo series of mitotic divisions and differentiation steps culminating into the preleptotene spermatocytes which then enter into the meiotic prophase following a single replication cycle. This phase is characterized by meiotic recombination and is followed by reduction division resulting in haploid round spermatids. These cells then undergo extensive morphological and nuclear changes to form a unique cell, spermatozoa. This entire germ cell differentiation process occurs in a unique environment present inside the seminiferous tubules which is created by the Sertoli cells, the somatic cells in the tubules by forming junctions with each other thus providing unique milieu to the developing germ cells. Within the tubule, the germ cells are also arranged in an orderly manner called stages of spermatogenesis indicating a complex mechanism of germ cell differentiation. This complex differentiation process is a consequence of developmentally and precisely regulated differential gene expression (Eddy, 2002). Unraveling the molecular mechanisms involved in the male germ cell development is an uphill task due to the complexity of the cyto-architecture existing in the tubules and further complicated by unavailability of established germ cell lines and lack of cell culture systems that facilitate the germ cell differentiation in vitro. Comparative gene expression analysis of spermatogenesis in nematodes, flies and rodents revealed highly conserved transcriptomes and have provided some insights into its regulation (Schlecht and Primig, 2003). However, these data fail to represent the genetic and biological complexity of human spermatogenesis. In the present study, an attempt has been made to identify the genes that are differentially expressed in human tetraploid and haploid germ cells and to investigate the mechanism of regulation of the genes expressed in the post-meiotic germ cells. To identify the cell type specific genes, expression profiling of the human tetraploid and haploid germ cells was carried out using cDNA microarray. These cells were purified by centrifugal elutriation (Meistrich et al., 1981; Shetty et al., 1996) from the human testicular tissues obtained from the patients undergoing orchidectomy as treatment for prostate cancer. Purity of the enriched population of the germ cells was ascertained by DNA flow cytometry and by RT-PCR analysis using the known cell-specific markers and ruling out contamination of the somatic cells such as the Sertoli cells and the Leydig cells. Microarray experiments were carried out with the RNA isolated from each cell type and labeling the cDNA with Cy3/Cy5-dUTP and hybridizing to the human 19K array chip (University Health Network, Toronto, Canada) containing 19,200 ESTs. Two independent hybridizations were carried out using the germ cells isolated from two individuals and the microarray data were analyzed using Avadis 3.1 software (Strand Life Sciences, India). Analysis of…
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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 | 0.001 | 0.001 |
| 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".