Phagocytosis and killing of Brucella by human polymorphonuclear leukocytes.

Although cellular immunity involving activated macrophages is important in resistance to Brucella, serum factors and polymorphonuclear leukocytes (PMNLs) play some role in the initial response to infection. The interaction between human PMNLs and virulent and attenuated strains of Brucella abortus and Brucella melitensis was studied by in vitro techniques. Virulent and attenuated strains of both species were rapidly phagocytosed after opsonization with normal human serum (NHS); nonopsonized bacteria were not phagocytosed.

Polypeptide profiles of chlorophyll . protein complexes and thylakoid membranes of spinach chloroplasts.

In addition to the major chlorophyll . protein complexes I and II, two minor chlorophyll proteins have been observed in sodium dodecyl sulfate (SDS))-polyacrylamide gels of spinach chloroplast membranes. These minor pigmented zones appeared to be derived from the light-harvesting chlorophyll a/b .

The effect of rodent seed predation on four species of California annual grasses.

The effect of seed predation by Microtus californicus and Mus musculus on plant numbers of four species of California annual grasses was investigated for one year period on a grassland near Davis, California. In winter, mice utilized dead star thistle plants for cover when grasses in open areas were short, but moved into open areas when grass grew tall in spring.Using exclosures and plots sown with known quantities of seed, it was estimated that a mouse population (approximate density 120/acre) consumed 75% of Avena fatua seed, 44% of Hordeum leporinum seed, and 37% of Bromus diandrus seed.