Variations among unbred heifers in the activities of polymorphonuclear leucocytes from the mammary gland and blood

The phenotypic characteristics are described for the activity of polymorphonuclear leucocytes NMN) obtained by either lavage of the cavity system of juvenile mammary glands stimulated with a synthetic muramyl dipeptide analogue or isolation from the peripheral blood. Attention was paid to the variability of characteristics and its sources, and to correlations among them. The following characteristics were investigated in 27 clinically healthy, unbred Bohemian Red Pied x Holstein heifers: migration activity in situ, number of phagocytosing PMN, phagocytotic index, bactericidal activity of PMN and unstimulated and zymosan-stimulated luminol-dependent chemiluminescence. Considerable individual variation was found in the characteristics. Significant differences between blood PMN and PMN from lavages after influx induction were found for bactericidal activity (P < 0.05) and chemiluminescence (P < 0.01). A significant correlation between blood PMN and mammary gland PMN was found only for the number of phagocytosing cells (r = 0.329; P < 0.01). Highly significant positive correlations (P < 0.01) were demonstrated between the number of phagocytosing PMN [a], phagocytotic index [b], and bactericidal activity [c] in both blood PMN (r(ab) = 0.602; r(ac) = 0.565; r(bc) = 0.529) and mammary gland PMN (r(ab) = 0.730, r(ac) = 0.618, r(bc) = 0.589). No significant correlation was demonstrated for non-stimulated (NS), zymosan-stimulated (ZS), or opsonized zymosan-stimulated (OZS) chemiluminescence with any of the other characteristics of phagocytotic activity, in either blood PMN or mammary gland PMN (P > 0.05). The animal was a highly significant source of variability for all the phagocytotic activity characteristics (P < 0.01). Udder quarter was a non-significant source of variability for all the characteristics of phagocytotic activity except for NS chemiluminescence (P < 0.05) and ZS or OZS chemiluminescence (P < 0.01). However, udder quarter was a non-significant source of variability of chemiluminescence indices ZS/NS and OZS/NS (P > 0.05). It has been demonstrated that in situ migration activity, the number of phagocytosing PMN, phagocytotic index, bactericidal activity of PMN and chemiluminescence indices of PMN collected from juvenile mammary glands of unbred heifers after influx induction can be regarded as candidate early markers of resistance to mammary infections.     

Agriculture. Variety spices up Chinese rice yields

The results of Chinese field trials reinforce the accepted scientific wisdom that planting different varieties of a crop in the same field holds down the spread of certain diseases and improves yields. And this time researchers seem to have convinced farmers, too.     

Ninth International Coral Reef Symposium. Reef migrations, bleaching effects stir the air in Bali

More than 1500 marine biologists, ecologists, conservationists, and community activists met at this Bali resort from 23 to 27 October for the Ninth International Coral Reef Symposium. Topics included the dynamics of reef fish communities and the lingering impacts of coral bleaching.     

ELECTION 2000: Uncertainty Wins by a Landslide

Scientists seeking order from the chaos of the U.S. election results may have a long wait. With the closest presidential election in a generation still undecided as Science went to press and the winners in several closely watched Senate and House races also unknown, it may be months before researchers and science lobbyists know who will fill influential posts in Congress and the new Administration for shaping science policies and budgets.