Transcriptome Analysis of Bull Semen with Extreme Nonreturn Rate: Use of Suppression-Subtractive Hybridization to Identify Functional Markers for Fertility

• Published in: Biology of reproduction 2008-04, Vol.78 (4), p.618-635
• Main Authors: Lalancette, C, Thibault, C, Bachand, I, Caron, N, Bissonnette, N
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cattle; Cattle Diseases - genetics; Fertility - genetics; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Profiling; Gene Library; Infertility, Male - genetics; Infertility, Male - veterinary; Male; Molecular and cellular biology; Molecular genetics; Nucleic Acid Hybridization - methods; Oligonucleotide Array Sequence Analysis; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - analysis; Semen - chemistry
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.106.059030

Spermatozoa are terminally differentiated cells produced during the complex process of spermatogenesis. Although the role of their residual RNA content is still being debated, this transcriptome may represent a fingerprint of spermatogenesis quality. In the present study, we undertook differential transcript profiling of spermatozoa from fertile bulls with extreme nonreturn rates (NRRs): a low-fertile group, and a high-fertile group. Using the suppression-subtractive hybridization technique in combination with macroarray analysis, we also identified novel genes. Both extreme NRR index groups retained redundant identity, such as ribosomal and mitochondrial sequences, at a statistically significant level. An elevated number of 12S, 18S, and Large Chain R rRNA gene copies were found in low-fertile bulls and validated in spermatozoa by quantitative RT-PCR for a small cohort of bulls with known fertility index. Whereas the high-NRR library exhibited a large proportion (29%) of transcripts associated with known functions (e.g., metabolism, signal transduction, translation, glycosylation, and protein degradation), only 10% of the low-NRR sequences did. This difference is also conveyed by two other categories: 17% Bovine Genome and 48% unknown in the high-NRR library, compared with 3% and 80%, respectively, in the low-NRR library. Some of the unknown transcripts are similar to expressed sequence tags detected in the male reproductive organ of certain plants and retain homology to a putative human protein. Whereas the individual transcriptome profiles may be useful in fertility assessment, these findings also suggest cross-species conservation, could contribute to a better understanding of spermatogenesis, and provide new insights regarding idiopathic infertility.