No abstract

The IVM of mammalian cumulus–oocyte complexes (COCs) yields reduced oocyte developmental competence compared with oocytes matured in vivo. Altered cumulus cell function during IVM is implicated as one cause for this difference. We have conducted a microarray analysis of cumulus cell mRNA following IVM or in vivo maturation (IVV). Mouse COCs were sourced from ovaries of 21-day-old CBAB6F1 mice 46 h after equine chorionic gonadotrophin (5 IU, i.p.) or from oviducts following treatment with 5 IU eCG (61 h) and 5 IU human chorionic gonadotrophin (13 h). IVM was performed in α-Minimal Essential Medium with 50 mIU FSH for 17 h. Three independent RNA samples were assessed using the Affymetrix Gene Chip Mouse Genome 430 2.0 array (Affymetrix, Santa Clara, CA, USA). In total, 1593 genes were differentially expressed, with 811 genes upregulated and 782 genes downregulated in IVM compared with IVV cumulus cells; selected genes were validated by real-time reverse transcription–polymerase chain reaction (RT-PCR). Surprisingly, haemoglobin α (Hba-a1) was highly expressed in IVV relative to IVM cumulus cells, which was verified by both RT-PCR and western blot analysis. Because haemoglobin regulates O2 and/or nitric oxide availability, we postulate that it may contribute to regulation of these gases during the ovulatory period in vivo. These data will provide a useful resource to determine differences in cumulus cell function that are possibly linked to oocyte competence.

Three novel gene products have been cloned by differential screening of a dog epididymis cDNA library as part of a global appraisal of specific gene expression in the epididymis. The predicted proteins were provisionally named CE8-CE10 (for canine epididymal gene products 8-10). Northern blot analyses and in situ transcript hybridization confirmed that the cDNAs were all derived from tissue-specific, moderately to highly abundant mRNAs of the epididymal epithelium, showing a distinct regionalized expression pattern within the epididymal duct. Their sequences predict (i) a novel 19 kDa member of the Ly-6-domain protein superfamily (CE8), (ii) an approximately 30 kDa protein with multiple membrane-spanning regions (CE9), and (iii) a novel approximately 13 kDa single whey acidic protein domain protein (CE10). Closely related, cross-hybridizing gene products were abundant in the epididymis of stallions and bulls, but not in rodents or men. Changes in mRNA frequency were observed that specifically correlated with a cryptorchid situation and with the age of the dogs. Gene products restricted to the caput epididymidis were affected by both conditions, while those with a wider regional distribution were not.

No abstract