Browsing by Author "Coleman, Stephen, advisor"

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Open Access
Equine fecal microbiota changes associated with anthelmintic administration
(Colorado State University. Libraries, 2018) Kunz, Isabelle, author; Coleman, Stephen, advisor; Hess, Tanja, committee member; Hassel, Diana, committee member; Metcalf, Jessica, committee member
The equine gastrointestinal tract contains a complex ecosystem comprised of microorganisms and intestinal helminth parasites. Increasing evidence suggests that horses rely on their gastrointestinal microbial populations for many aspects of metabolic and immune function. Furthermore, interactions between the microbes, helminths, and their host may impact these functions, which are vital to maintaining gastrointestinal homeostasis. The use of anthelmintic drugs is a common practice of intestinal helminth parasite control in domestic horse health management. The use of anthelmintic drugs is very effective for controlling the burden of parasitic infection and associated clinical signs, however anthelmintic administration has also been associated with gastrointestinal disturbances in the horse. The potential effects of anthelmintic drug administration on the equine gastrointestinal microbiota and its' role in homeostasis is not yet understood. The objective of research presented in this thesis is to investigate the impact of anthelmintic administration on the equine gastrointestinal microbiota. This goal was addressed in two main studies, which used 16S rRNA amplicon sequencing to identify and describe the microbial populations present in equine fecal samples. The first study described is a pilot project which aimed to characterize the impact of anthelmintic treatment on the fecal microbiota of horses without an observable helminth infection. The results of this study indicated that subtle differences in the microbial community composition and structure are detectable between samples collected before and after anthelmintic treatment. A second study was then conducted as a follow-up to the pilot which included horses with varying detectable levels of helminth infection as determined by fecal egg counts. Results of the second study further demonstrated microbiota changes following anthelmintic treatment, while also suggesting that the most notable effects of anthelmintic treatment may be observed in fecal samples between 48 and 72 hours post-treatment. The results of these studies suggest that anthelmintic treatment may be associated with changes in the equine fecal microbiota.
Embargo
Transposable elements and early pregnancy in the horse
(Colorado State University. Libraries, 2024) Southerland, Sierra L., author; Coleman, Stephen, advisor; Bruemmer, Jason, committee member; Fedorka, Carleigh, committee member; Pinedo, Pablo, committee member; Chicco, Adam, committee member
Understanding the molecular events and physiological dynamics in the endometrium during early pregnancy is crucial for improving our understanding of reproductive outcomes in horses. Much of the work investigating early pregnancy in the horse has focused on maternal recognition of pregnancy (MRP). This critical signal, which initiates the pathways and regulatory changes to help make the endometrium receptive to pregnancy, remains elusive in the horse. Transposable elements (TEs), once overlooked components of the genome, have been implicated in regulating gene expression during critical stages of embryo and placental development. The current study investigated the expression of TEs during the early phase of pregnancy post-ovulation. The hypothesis tested was that pregnancy status would impact the expression patterns of TE-derived transcripts in the endometrium around the time of maternal recognition. It was anticipated that the TE transcripts would increase in the endometrium of pregnant mares either in response to or as a part of the maternal recognition signal. RNA sequencing data was generated from endometrial biopsies at days 9, 11, and 13 in pregnant and non-pregnant mares. Bioinformatics analyses identified distinct patterns of TE expression across the duration of early pregnancy. Contrary to expectations, these findings did not reveal the accumulation of TE transcripts in the pregnant endometrium compared to the non-pregnant endometrium during early pregnancy. Instead, there was a significant decrease in the number of differentially expressed transcripts over the time points studied. These results challenge the initial assumption and suggest that the regulation of TE transcriptional activity during early pregnancy may be more complex than previously thought, highlighting the need for further research into the roles of TEs in equine reproductive physiology. An alternative explanation for the results of this analysis is that maternal recognition of pregnancy may involve the downregulation of transcripts expressed from TEs, potentially serving as a switch to prevent luteolysis and maintain pregnancy. This study underscores TEs as potential biomarkers and regulators in equine reproduction, providing insights into endometrial processes and offering avenues for improving fertility outcomes and breeding efficiency in horses.