Haploid selection in Equus caballus: Effect of sperm fitness on sperm 1 morphology, DNA and chromatin structure

Hesketh, Ella Frances (2024) Haploid selection in Equus caballus: Effect of sperm fitness on sperm 1 morphology, DNA and chromatin structure. Masters thesis, University of East Anglia.

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Abstract

Haploid selection during sexual reproduction occurs naturally through sperm competition within the ejaculate of a male. Mimicking selection in vitro involves a solid understanding of sperm fitness, and methods to select for fitness qualities. This current study developed a sperm selection assay in horses (Equus caballus) using a viscous medium, methylcellulose, to select sperm based on penetration ability, deeming it as “fitter”. Sperm which did not penetrate the media is referred to as less fit or un-fit. Penetrating sperm (outer condition) and non-penetrating sperm (centre condition) was isolated and selected, post 2 hour incubation, for staining to compare morphological and DNA integrity differences between the two conditions. Initial sperm prior to incubation was also stained for comparison. Employing the selection method, SpermBlue® staining was used to determine morphologically normal and abnormal sperm and toluidine blue to identify DNA fragmentation and chromatin packaging. Selected sperm which penetrated methylcellulose (outer condition) showed higher numbers of morphologically normal sperm but less DNA integrity compared to sperm that did not penetrate methylcellulose during incubation. Fitter sperm also showed lower levels of viability post-incubation. The results from the study suggest fitter sperm has better morphology, allowing them to penetrate the media. However, longevity of this sperm is compromised, leading to higher levels of DNA damage. This study provides an important insight into the consequences and trade-offs between fitness and DNA quality in stallion sperm, with potential applications for improving equine artificial insemination methods and research.

Item Type:	Thesis (Masters)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	20 Mar 2025 14:27
Last Modified:	20 Mar 2025 14:27
URI:	https://ueaeprints.uea.ac.uk/id/eprint/98831
DOI:

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