Document Type : Original Article
Authors
1
Department of Medical Biotechnology, Faculty of Biotechnology, Al-Qadisiyah University, Al-Diwaneyah, Iraq
2
Department of Agricultural Biotechnology, Faculty of Biotechnology, Al-Qadisiyah University, Al-Diwaneyah, Iraq
Abstract
Introduction: Exposure to heavy metals is linked to impaired animal fertility through disruptions in gene expression in spermatozoa. However, the mechanisms behind these effects are not fully understood. This study aimed to assess the impact of long-term consumption of shallow well water contaminated with heavy metals on semen quality and mRNA expression of genes related to sperm tail formation in rams.
Materials and Methods: Eighty sexually mature rams were enrolled, including 40 from four locations in Al-Diwaniyah governorate (Al-Shamiya, Al-Dughara, Al-Hamza, and Al-Shanafiya), which had been drinking shallow well water since birth (experimental group), and 40 drinking municipal tap water (control group). Water samples were analyzed for pH, total dissolved solids, salinity, turbidity, and heavy metal content (cadmium, lead, mercury). Semen was collected using an artificial vagina and evaluated by computer-assisted sperm analysis (CASA). Total RNA was extracted from spermatozoa, and the expression of CATSPER, AKAP4, and SPAG6 genes was quantified using one-step real-time PCR with SYBR Green.
Results: Shallow well water had significantly higher turbidity, salinity, dissolved solids, and heavy metal concentrations compared to tap water (p ≤ 0.05). Rams drinking well water showed a significantly lower percentage of motile sperm (p < 0.001). Additionally, the expression levels of CATSPER, AKAP4, and SPAG6 genes were significantly reduced in the well water group compared to the control group (p < 0.001). Specifically, CATSPER expression decreased by 85.5%, AKAP4 by 82.8%, and SPAG6 by 87.4% in the well water group relative to controls.
Conclusions: Chronic exposure to contaminated shallow well water markedly impairs sperm motility and downregulates key genes involved in tail formation in rams, emphasizing the reproductive risks of heavy metal pollution.
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