The Effect of Stage of Lactation and Parturition on Galectin Expression in Cow Blood

The aim of this study was to evaluate the expression of galectins in cow blood and evaluate their modulation in periparturient cows at different stages of lactation. Galectins are multipotent, evolutionarily conserved, carbohydrate- binding proteins that, by crosslinking cell surface glyco-conjugates, trigger a cascade of transmembrane signaling events such as cell activation, cytokine secretion, migration, and apoptosis There are 15 galectin protein subtypes that all share the shared characteristic of amino acid sequences and affinity for β-galactoside sugars. Galectins are known to have an impact on immuno-modulation and are involved in uterine immunoregulation during pregnancy.. The cows were grouped into three lactation periods (1^st,2^nd and 3^rdlactations). Blood was taken 2 weeks close to parturition (close up), and 7 days after parturition(c+7) at Michigan State University dairy farm and shipped in Paxgene tubes for analysis. Total RNA was isolated, reverse transcribed to cDNA, and then used in real time PCR experiments. With the use of Primer-Blast from NCBI, specific primers for galectins 1, 2, 3, 4, 7,8, 9,12 and Beta actin (forward and reverse) were sequenced and used for this project. Beta actin was used as internal control. Fold change in transcript abundance was calculated using the Livak method.

In first lactation cows, Galectin 1 was turned off after parturition. Galectin 2 was absent in both close up and c+7 cows. Galectins 3 and 7 were present in both close-up and c+7 cows but levels did not change after parturition (Fold change< 2). Galectin 4 was present before parturition but absent a week after parturition, Galectin 9 expression increased after parturition (fold change =2). Galectin 12 was turned off after parturition. In 2^nd lactation, cows, Galectin 1 was turned off after parturition, and Galectins 2, 3 ,7 and 9 increased in transcription after parturition (fold change >2). Galectins 1,4,8 and 12 were present before and after parturition but their fold changes were not significant. In 3^rdlactation cows, all 8 galectins except for galectin 8 were detected in both close ups and c+7 cows. Expression levels for these galectin genes did not change (fold change<2).

All genes tested were expressed in cow blood at varying levels. It is clear from this study that galectin gene expression is affected by stage of lactation and parturition. Further studies are needed to determine the factors that contribute to the different galectin expressions in cow blood during the periparturient period.