Molecular cloning and expression of bottlenose dolphin CD34

CD34 Protein: Its expression and function in inflammation

CD34 has spear-headed the field of basic research and clinical transplantation since the first reports of its expression on hematopoietic stem cells (HSCs). Expressed in mice, humans, rats and other species, CD34 has been used for more than 40 years as a hematopoietic stem and progenitor cell marker. It was later found that muscle satellite cells and epidermal precursors can also be identified with the aid of CD34. Despite the usefulness of CD34 as a marker of HSCs, its overall purpose in animal physiology has remained unclear. This review recaptures CD34 structure, evolutionary conservation, proposed functions, and role in lung inflammation, to describe current research findings and to provide guidance for future studies on CD34.

Cloning and characterization of bottlenose dolphin (Tursiops truncatus) interleukin-10

The function of cytokines in cetaceans has so far only been determined for the proinflammatory cytokines. In this study, we cloned bottlenose dolphin (Tursiops truncatus) interleukin-10 (IL-10) cDNA from concanavalin A (Con A)-stimulated peripheral blood mononuclear cells (PBMC), and investigated the mRNA expression levels in various tissues and the bioactivity of recombinant dolphin (rd) IL-10. The gene encodes a polypeptide of 178 amino acids which encompasses the mature protein sequence of 158 amino acids. Quantitative expression analysis of dolphin IL-10 revealed that the highest mRNA levels are found in the spleen. To assess its function, rdIL-10 was produced in human embryonic kidney 293 cells and its bioactivity was demonstrated through IL-10-induced inhibition of proinflammatory cytokine mRNA expression IFN-γ, TNF-α, and IL-2 of Con A-stimulated PBMC. These results indicated that the structure and function of bottlenose dolphin IL-10 is similar to that of other animals. This is the first report of the characterization of an anti-inflammatory cytokine in cetaceans.

Molecular characterization and validation of commercially available methods for haptoglobin measurement in bottlenose dolphin

Haptoglobin (Hp) is a positive acute-phase protein and a valuable marker of inflammation in both human and veterinary medicine. The aim of this study was to validate the molecular characterization of Hp in dolphins and to validate commercially available Hp measurement methods such as Hp-ELISA (originally designed for pigs) and Hp-hemoglobin (Hb) binding assay. The dolphin Hp (dHp) amino acid sequence appeared most similar to pig Hp by sequence homology and phylogenetic clustering. Amino acid sequence analysis revealed that dHp comprises the Hp1 form of α1 and β chains. The anti-pig Hp antibody cross-reacted with both recombinant dHp, expressed by Escherichia coli, and dHp from serum. The intra- and inter-assay levels of imprecision of pig Hp-ELISA and the Hp-Hb binding assay were found to be tolerable for the determination of Hp in dolphin, and there was no significant discrepancy between the two determination methods. The ability of the assay to differentiate between healthy and inflammation groups was investigated, and a significant increase in Hp concentration was detected in inflammatory conditions. Thus, Hp is a useful inflammation marker for dolphin, and the Hp concentration in dolphin serum samples can be reliably measured using commercially available pig Hp-ELISA and Hp-Hb binding assay.

Characterization of the circulating serum amyloid A in bottlenose dolphins

Several isoforms of serum amyloid A (SAA) have been identified so far and because the plasma concentration of it increases dramatically, it is used as an indicator of inflammation in animals. In many terrestrial mammals, the circulating isoforms are SAA1 and SAA2, which are synthesized in the liver. Extra-hepatically synthesized SAA3, however, is a predominantly local SAA isoform with a characteristic N-terminal TFLK motif and a highly alkaline isoelectric point (pI). The aim of this study was to characterize the circulating SAA isoforms in bottlenose dolphins (dSAA) by determining the deduced amino acid sequence isolated from liver and the pI of plasma from healthy dolphins and those with inflammation. The deduced amino acid sequences of dSAA showed characteristics of SAA3 with an N-terminal TFLK motif, a predicted alkaline pI and were phylogenetically clustered with the SAA3 group rather than the SAA1 and SAA2 groups. Various tissues contained dSAA mRNA with the highest levels being detected in the liver. Isoelectric focusing and western blot analysis showed that one highly alkaline SAA was markedly detected in plasma obtained from dolphins affected by inflammation. These results suggest that, unlike other mammals, the circulating SAA in dolphins exhibits SAA3 properties, as is the case in pigs.