Date of Graduation

12-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Cell & Molecular Biology (PhD)

Degree Level

Graduate

Department

Cell & Molecular Biology

Advisor/Mentor

Rath, Narayan C.

Committee Member

Wideman, Robert F. Jr.

Second Committee Member

Lay, Jackson O. Jr.

Third Committee Member

Dridi, Sami

Keywords

Biomarkers; Femoral head separation; Glucocorticoids; Lipopolyscahharides; Mass Spectrometry; Proteomics

Abstract

During the last 50 years, animal breeding programs in commercial poultry have made significant progress in the bodyweight gain of broilers but led to several metabolic and skeletal disorders. Lameness associated with proximal femur known as femoral head separation (FHS) or femoral head necrosis (FHN) is one of the major metabolic disorders in poultry industry. In order to select for healthy chickens, markers that can distinguish between healthy and affected birds are required. Biomarkers from blood represent an ideal and rich source of markers which can be obtained using minimally invasive methods. The biomarkers were explored in an experimental model for FHS where samples from spontaneously affected broilers and lipopolysaccharides (LPS) injected broilers were analyzed using matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). In the plasma of glucocorticoid induced FHS, there was an increase in apolipoprotein A-I (Apo-AI), whereas proteins such as vascular endothelial growth factor-C-isoform-1 (VEGF-C-1) and Protocadherin-15 (PCDH-15) were absent in FHS predisposed chickens. The increase in Apo AI may lead to vascular thromboembolism, and the lack of VEGF and PCDH-15 can be associated with vascular insufficiency and cell-adhesion problems, respectively. In spontaneously FHS affected birds, decrease in fetuin, fibrinogen, alpha-1 acid glycoprotein (AGP), and increases in Apo-AI, gallinacin-9, and hemoglobin chains were observed. These proteins could be related to skeletal mineralization disorders, coagulation problems, platelet aggregation, dyslipidemia, hemorrhage and erythrolysis. Due to the involvement of one or more acute phase proteins such as AGP and defensin, we tested the changes in protein profile of chicken plasma in response to LPS. Proteins AGP, cathelicidin-2, heperanase, chemokine CCLI10 were increased in response to LPS, which was different and distinct from FHS affected birds. Hence, the distinct protein profile of FHS affected birds could be useful as candidate biomarkers for distinguishing healthy birds from susceptible or affected chickens.

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