Bactericidal activity of lachrymal secretion and complement system in copper deficient bovines.

Copper deficiency in humans and animals has been related to increased susceptibility to infections. Neutrophils are one of the most studied components of the immune response; however, to the best of our knowledge, other defenses of the innate immune system have not been analyzed in copper-deficient animals. Our previous studies in copper-deficient bovines have shown increased susceptibility to infectious keratoconjunctivitis, an ocular disease caused by Moraxella bovis. The objective of this work was to evaluate the bactericidal activity of lachrymal secretion and complement system, two main mechanisms of the innate immune response against M. bovis, in copper-deficient cattle. Our results indicate that copper deficiency has no effect on bactericidal activity of complement system and lachrymal secretion against M. bovis in calves. Other components of local and systemic ocular defense mechanisms that could explain the increased susceptibility to infectious keratoconjunctivitis observed in copper-deficient bovines should be investigated.

Dietary calcium deficiency increases Ca2+ uptake and Ca2+ extrusion mechanisms in chick enterocytes.

Ca2+ uptake and Ca2+ extrusion mechanisms were studied in enterocytes with different degree of differentiation from chicks adapted to a low Ca2+ diet as compared to animals fed a normal diet. Chicks adapted to a low Ca2+ diet presented hypocalcemia, hypophosphatemia and increased serum 1,25(OH)2D3 and Ca2+ absorption. Low Ca2+ diet increased the alkaline phosphatase (AP) activity, independently of the cellular maturation, but it did not alter gamma-glutamyl-transpeptidase activity. Ca2+ uptake, Ca2+-ATPase and Na(+)/Ca2+ exchanger activities and expressions were increased by the mineral-deficient diet either in mature or immature enterocytes. Western blots analysis shows that vitamin D receptor (VDR) expression was much higher in crypt cells than in mature cells. Low Ca2+ diet decreased the number of vitamin D receptor units in both kinds of cells. In conclusion, changes in Ca2+ uptake and Ca2+ extrusion mechanisms in the enterocytes by a low Ca2+ diet appear to be a result of enhanced serum levels of 1,25(OH)2D3, which would promote cellular differentiation producing cells more efficient to express vitamin D dependent genes required for Ca2+ absorption.