The Impact of a PGYM Variant on Myophosphorylase Deficiency in Red Angus Composite Cattle and Changes in the Skeletal Muscle Transcriptome Due to the Intramuscular Administration of Lidocaine in Wether Lambs

Authors

Mackenzie Christin Batt, University of Nebraska-LincolnFollow

First Advisor

Jessica L. Petersen

Date of this Version

5-2024

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial tulfillment of requirements for the degree of Master of Science

Major: Biological Sciences

Under the Supervision of Professor Jessica L. Petersen

Lincoln, Nebraska, May 2024

Comments

Copyright 2024, Mackenzie Christin Batt. Used by permission

Abstract

Project 1 focused on eight calves in a Nebraska herd (composite Simmental, Red Angus, Gelbvieh) that displayed exercise intolerance during forced activity. Available sire pedigrees contained a paternal ancestor within 2-4 generations in all affected calves. Pedigrees of the calves’ dams were unavailable, however, the cows were ranch-raised and retained from prior breeding seasons, where bulls used for breeding occasionally had a common ancestor. Therefore, it was hypothesized that a de novo autosomal recessive variant was causative of exercise intolerance in these calves. A genome-wide association analysis followed by whole-genome sequencing led to the identification of a variant in the gene PYGM (BTA29:g.42989581G>A). The variant, confirmed to be present in the skeletal muscle transcriptome, was predicted to produce a premature stop codon (p.Arg650*). The protein product of PYGM, myophosphorylase, breaks down glycogen in skeletal muscle. Myophosphorylase deficiency poses welfare concerns for affected animals and negatively impacts the final product.

Project 2 examined the impact of lidocaine usage on muscle used to study the transcriptome. Lidocaine acts by blocking sodium channels necessary for sensory neurons to relay pain signals to the brain. In animal research, lidocaine is used to ensure animal comfort during tissue biopsy. Biopsied samples may then be used to study the transcriptome, assuming that lidocaine-treated tissue reflects genomic activity of untreated tissue. The objective of this study was to determine the effect of intramuscular lidocaine injection on skeletal muscle gene expression in sheep. RNA sequencing analysis was performed on muscle samples collected from lidocaine-treated and untreated limbs. Lidocaine administration led to differential expression of genes associated with immune response modulation, inflammatory suppression, and muscular function. Despite variations in gene expression profiles between validation samples, commonalities were observed in pathways related to inflammation and muscular function, emphasizing the need for cautious interpretation of transcriptomic data in the presence of pharmacological interventions like lidocaine.

Advisor: Jessica L. Petersen