Human Spermatogenesis : Differential Gene Expression And Regulation
Notice bibliographique
Résumé
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…
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».