Anwar Khurshaid, Thaller Georg, Saeed-Zidane Mohammed
Molecular Genetics Group, Institute of Animal Breeding and Husbandry, Christian-Albrechts-University Kiel, 24118 Kiel, Germany.
Int J Mol Sci. 2024 Dec 5;25(23):13064. doi: 10.3390/ijms252313064.
Sperm mitochondria are vital organelles for energy production and pre- and post-fertilization sperm functions. The potential influence of the age of the bull and season on the sperm-borne mitochondrial copy number and the transcription activity has not yet been investigated. Therefore, the expression patterns of all protein-coding mitochondrial genes were identified throughout the year along with mitochondrial copy numbers in young and old bulls' spermatozoa. For that, high-quality semen samples ( = 32) with more than 80% quality for the morphological parameters, from young ( = 4, aged 18-24 months old) and old ( = 4, aged 40-54 months old) Holstein bulls, were collected during the four seasons ( = 4 samples each animal/season). The DNA and RNA were isolated from sperm cells and subjected to the DNA copy number and expression analyses using qPCR. Furthermore, an in silico analysis using gene ontology online tools for the abundantly expressed genes was utilized. The data were statistically analyzed using Prism10 software. There was a significant reduction in the mitochondria copy number of young bulls' spermatozoa compared to their old counterparts during the summer (29 ± 3 vs. 51 ± 6, < 0.001) and winter (27 ± 3 vs. 43 ± 7, < 0.01) seasons. However, sperm-borne mitochondrial protein-coding genes were transcriptionally higher in young bulls throughout the year. Within the same group of bulls, unlike the old bulls, there was a significant ( < 0.05) induction in the transcription activity accompanied by a significant ( < 0.05) reduction in the mitochondrial copy numbers in the summer (29 ± 3) and winter (27 ± 3) compared to the spring (42 ± 9) and autumn (36 ± 5) seasons in young bulls. Additionally, the pathway enrichment of the top six expressed genes differed between age groups and seasons. In conclusion, under the same quality of semen, the early stages of age are associated with mitochondrial biogenesis and transcription activity dysregulation in a season-dependent manner.
精子线粒体是能量产生以及受精前后精子功能的重要细胞器。种公牛年龄和季节对精子携带的线粒体拷贝数及转录活性的潜在影响尚未得到研究。因此，本研究确定了全年年轻和老龄种公牛精子中所有蛋白质编码线粒体基因的表达模式以及线粒体拷贝数。为此，从年轻（n = 4，年龄18 - 24个月）和老龄（n = 4，年龄40 - 54个月）的荷斯坦种公牛中收集了形态学参数质量超过80%的高质量精液样本（n = 32），在四个季节（每个动物/季节n = 4个样本）进行采集。从精子细胞中分离DNA和RNA，并使用qPCR进行DNA拷贝数和表达分析。此外，利用基因本体在线工具对高表达基因进行了计算机分析。使用Prism10软件对数据进行统计分析。在夏季（29 ± 3 vs. 51 ± 6，P < 0.001）和冬季（27 ± 3 vs. 43 ± 7，P < 0.01），年轻种公牛精子的线粒体拷贝数相比老龄种公牛显著减少。然而，年轻种公牛全年精子携带的线粒体蛋白质编码基因转录水平更高。在同一组公牛中，与老龄公牛不同，年轻公牛在夏季（29 ± 3）和冬季（27 ± 3）的转录活性相比春季（42 ± 9）和秋季（36 ± 5）季节有显著（P < 0.05）诱导，同时线粒体拷贝数显著（P < 0.05）减少。此外，年龄组和季节之间前六个表达基因的通路富集情况不同。总之，在精液质量相同的情况下，年龄早期阶段与线粒体生物发生和转录活性的失调存在季节依赖性关联。
