Sex-Related Differences in UT-B Urea Transporter Abundance in Fallow Deer Rumen

Abstract

Rumen studies have focused almost exclusively on livestock species under strictly regimented diets. This means that the ruminal condition of free-living and free-feeding wildlife remains practically unstudied. Urea nitrogen salvaging, a process by which urea is passed into the rumen, to both provide a valuable source of nitrogen for bacterial growth and to buffer the potentially harmful acidic effects of bacterial short chain fatty acids, has remained unexplored in wild ruminants, such as deer. UT-B2 transporters are the key proteins reported to facilitate the transepithelial ruminal urea transport. In this study, we investigate the expression, abundance and localisation of urea transporters in the rumen of a semi-wild fallow deer (Dama dama) population. Physical measurements confirmed that males had larger rumen than females, while adults had longer papillae than juveniles. Initial RT-PCR experiments confirmed the expression of UT-B2, while immunolocalisation studies revealed that strong UT-B staining was present in the stratum basale of deer rumen. Western blotting analysis demonstrated that a 50 kDa UT-B2 protein was significantly more abundant in adult females compared to adult males. This study confirms the presence of UT-B2 urea transporters in deer rumen and suggests that sex-related differences occur, bringing new insight into our understanding of rumen physiology.

Dietary regulation of ruminal UT-B2 urea transporters in adult male fallow deer bucks: effects of season and wildlife feeding activity.

“…Next, immunolocalization studies confirmed that both MCT1 and UT-B2 transporter proteins were predominantly located in stratum basale, in agreement with our previous studies (Zhong et al, 2022c). For MCT1, our staining confirmed MCT1 protein was found in the stratum basale of all the male adult deer rumen, except M3.…”

“…Our recent investigations of the epithelial transporters with the rumen of a wild population of fallow deer, living in Phoenix Park in Dublin, have added new insight into the processes regulating these ruminal UT-B2 transporters. We have found that levels of the 50 kDa UT-B2 protein were significantly greater in the rumen of female adults compared to male adults that had recently been through the rutting season (Zhong et al, 2022c). Since these males had minimal food intake during that time (Apollonio & Di Vittorio 2004), these findings were interpreted as further evidence that UT-B2 abundance was highly regulated by its' role in SCFA buffering rather than just nitrogen requirements per se -as had been already reported in cows (Simmons et al, 2009) and goats (Lu et al, 2015).…”

“…For the animal feeding behaviour study, we compared 3 male adult animals from the consistent beggar and rare beggar groups, plus one male juvenile consistent beggar and one female consistent beggar. This was important to do because our previous studies had shown that UT-B2 abundance was comparatively low in male adults (Zhong et al, 2022c). We therefore wanted an indication if this was still the same in consistent beggars.…”

“…The aim of this pilot study was therefore to further investigate the effect of feeding behaviour on the abundance of ruminal UT-B2 urea transporters -at both tissue and cellular levels. Since our previous research showed sex-related differences (Zhong et al, 2022c), this study was restricted to focusing on the potential effects of dietary regulation in male adult deer only. In order to achieve this, two key comparisons were made: (i) between male adult rumen taken from animals culled less than one month after the rutting season (i.e.…”

Regional investigation of UT-B urea transporters in the rat brain

“…This difference suggests that our UTBc19 antibodies (i) may not detect rat UT-B protein as effectively as other species (e.g human), and (ii) are more effective for Western blotting rather than immunolocalization analysis. Indeed, this second observation has also been reported in a recent study on deer rumen samples using the UTBc19 antibodies [ 30 ]. Additionally, it should also be noted that all the animals investigated in this current study were male.…”