Giraffe’s urine: from urinalysis to proteomics and metabolomics

This thesis focused on defining the urinary reference values and investigating the urinary proteome and metabolome of captive giraffes (Giraffa camelopardalis) by using a non-invasive sampling method. Urine samples were collected with a syringe from the ground, immediately after spontaneous voiding, by aspirating the upper part of samples, to avoid them to come into contact with the soil contaminants as much as possible. To prove the sampling’s reliability, cow urines were used and the results of both types of samples (those collected in sterile urine cups and those collected from the ground with a syringe) were compared. This experiment revealed no statistical differences in the variables investigated (urine total protein, uTP; urine creatinine, uCrea; urine protein:creatinine ratio, UPC; number of protein bands and band protein quantification detected by 1D-electrophoresis-SDS-PAGE), which proved the reliability of this sampling technique. By establishing the urinary reference values as well as by identifying the urinary proteome, it was possible to obtain information about the renal function in giraffes for the first time. Just like other ruminants, urine of giraffes contains low quantity of proteins, the majority of which shows low molecular mass (MM). The proteins identified in their urines might act as a defence against microbes and play a role in the ability of giraffes to concentrate urine. A first insight into the urinary metabolome allowed to identify and quantify 39 molecules; this provided some information on some physiological adaptations of giraffes and were influenced by sex and age.