Thielen, Maria: mRNA expression of the acute phase protein haptoglobin in blood and milk somatic cells and cellular localisation within the mammary gland of dairy cows. - Bonn, 2006. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc:
author = {{Maria Thielen}},
title = {mRNA expression of the acute phase protein haptoglobin in blood and milk somatic cells and cellular localisation within the mammary gland of dairy cows},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2006,
note = {The haptoglobin (Hp) concentration in blood and milk is increasingly discussed as a diagnostic marker for bovine mastitis. This acute phase protein is mainly synthesised in the liver, however, Hp mRNA was also discovered in tissue homogenates of the bovine mammary gland. The aim of this study was to advance this finding by allocating Hp mRNA expression within the bovine mammary gland at the cellular level. Possible candidates are, firstly, cells of the mammary gland itself and, secondly, circulating leukocytes infiltrating the udder. The presence of the Hp mRNA in the latter cells was investigated by RT-PCR carried out with RNA extracted from bovine blood leukocytes as well as from milk somatic cells. In order to localise Hp mRNA expression at the cellular level within the mammary gland a protocol for in situ hybridisation was developed. Subsequently, this was applied to bovine mammary tissues infected with Escherichia coli (E. coli) or Staphylococcus aureus (Staph. aureus) by intracisternal inoculation 0, 6, 12 or 24 h pre-slaughter. In addition, blood and milk samples from these cows were analysed for the concentration of Hp protein collected during the 24 h infection and immediately pre-slaughter, respectively. In comparison to cattle, human leukocytes and mammary gland tissue were evaluated for Hp mRNA by RT PCR, because of existing, however contradicting evidence on Hp expression in man.
The results demonstrate that Hp mRNA is present in bovine leukocytes as well as milk somatic cells. Within the bovine mammary gland Hp mRNA expression could generally be assigned to the alveolar epithelial cells. In addition, E. coli pathogens caused a marked upregulation of Hp mRNA expression within hours after start of infection, whereas Hp mRNA expression in response to Staph. aureus infection appeared unchanged during the initial 24 h post-infection. These differences in mRNA presence between the pathogen types were matched by Hp protein concentrations measured in blood and milk. In humans, Hp mRNA was also evident in the mammary gland and in 50% of the leukocytes samples tested. In conclusion, this study identified novel cellular sites of Hp mRNA expression in dairy cows and, thus, possible sources of the Hp protein found in milk.},

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