Serum Protein Electrophoresis Reference Intervals for Six Species of Wild-Sampled Sharks in South Florida

Abstract

Serum proteins found in the blood have been used as diagnostic markers in both human and animal medicine. Evaluating proteins in the blood of sharks may be a valuable way to assess shark health. The purpose of this study was to perform serum protein electrophoresis from non-lethal blood samples of wild sharks and establish baseline values for six species off South Florida: blacknose (Carcharhinus acronotus), blacktip (Carcharhinus limbatus), bull (Carcharhinus leucas), lemon (Negaprion brevirostris), sandbar (Carcharhinus plumbeus), and tiger shark (Galeocerdo cuvier). Two hundred and fifty-one serum samples were collected between 2015-2018 along with sex determination and morphometric measurements. Agarose gel analysis was performed using mammalian protein fraction delimits albumin, alpha 1-globulins, alpha 2-globulins, beta globulins, and gamma globulins alternatively defined as fractions 1-5. Reference electrophoretic profiles were established for each species, revealing the dominance of protein fractions 3 and 4. The fraction 3:4 ratio was determined for each shark and reference intervals for total solids, protein fractions, and fraction 3:4 ratio are reported for each species. There were no significant differences in total solids or protein fractions between males and females of any species. In both blacktip sharks and bull sharks, total solids was positively correlated with body size, but not in the other species evaluated. In blacknose sharks, the fraction 3:4 ratio was positively correlated with body condition. Results suggest that there may be differences in total solids values across dry and wet seasons for some species. Newly established reference intervals can now be utilized in future research to evaluate the health of captive sharks and to investigate the health status of individuals in the wild as well as relate health measures to environmental conditions.

Increasing the data on elasmobranch plasma protein electrophoresis: electrophoretogram reference values determination in the undulate skate (Raja Undulata) and the nursehound shark (Scyliorhinus stellaris) maintained under human care

“…Proteins migrating in this region in different avian, reptile, and mammal species, have been characterized as alpha-2 macroglobulin, hapto-globulin, and ceruloplasmin; though the composition of these fractions in elasmobranchs has not been yet determined [ 4 , 22 ]. As previously described in other elasmobranchs species such as the blacknose shark ( Carcharhinus acronotus ), the blacktip shark ( Carcharhinus limbatus ), the bull shark ( Carcharhinus leucas ), the lemon shark ( Negaprion brevirostris ), the sandbar shark ( Carcharhinus plumbeus ), the tiger shark ( Galeocerdo cuvier ), the cownose ray, the bamboo shark and the bonnethead shark, alpha-1 fraction was smaller than alpha-2 fraction also in undulate skates and nursehounds [ 3 , 4 , 9 , 23 ]. Fraction 2 (equivalent to alpha-1 globulin) was significantly higher in undulate skates (median 12.75%, 1.47 g/l) compred to nursehounds (median 1.81% and 0.43 g/l), s both values between those reported for this fraction in other elasmobranch species such as the sand tiger shark (0.28% and 0.13 g/l), amboo shark (median 1.42% and 1.00 g/l) o bonnethead shark (4.82%, 2.80 g/l) showgreat interspecific variations.…”

“…However, this difference, even if statistically relevant, remains very tiny and even not relevant on concentration values. Despite variations in some electrophoretogram fractions have been related to sex and season in humans and domestic animal species, previous PPE studies with elasmobranchs did not detect statistically significant variations related to sex in different shark species including the blacknose, the blacktip, the nurse, bull, lemon, sandbar, and the tiger shark [ 11 , 22 , 23 ]. Fraction 4 (equivalent to beta-globulins) resulted significantly higher in female bamboo shark compared to male individuals, though the study did not determine shark reproductive status and the protein composition of this fraction [ 9 ].…”

“…Furthermore, the remaining fraction showing statistically significant differences in nursehound (fraction 8), corresponded to proteins migrating in the gamma-globulin region, which has been considered to represent IgM in teleost and has also been described to vary significantly not only during infection, but also with age and season in different animal species [ 11 ]. While our study followed ASVCP guidelines for the determination of reference values in clinically healthy populations, it is important to consider that within the few PPE studies performed with elasmobranchs, there is sometimes a mix of healthy and diseased individuals, which should be reflected and considered as this can significantly influence the reliability of the values provided [ 3 – 5 , 9 , 22 , 23 ]. Understanding which electrophoretic changes are related with sex or developmental stage in elasmobranchs is key for the correct interpretation of plasma protein fraction values and to differentiate which abnormalities are due to ongoing pathologic processes or to physiological variations.…”

“…Samples were selected to form part of the RI after the detailed evaluation of every animal’s medical history and the completion of physical examinations (which included a hematological and biochemical analysis) to evaluate the condition of each individual sampled. For this study, we divided the electrophoretogram into several fractions following the guidelines established in previous studies with elasmobranchs, which already defined five different fractions in ray and shark species [ 3 , 4 , 9 , 22 , 23 ]. Caution was taken to delete the injection peak and the end delimiter produced by the urine buffer before electrophoretogram interpretation and division into fractions for its analysis.…”