Determination of progesterone directly in milk fat as an improved method for fertility control in cattle

A simple and reliable method for the determination of progesterone in milk fat by radioimmunoassay has been developed. Application of the assay under field conditions has shown that all samples diagnosed " questionable" in the former milk progesterone test (MPT) could be characterized as positive or negative. Thus the total figure of animals daignosed correctly rose from 72.3% to 85.8%. The borderlines (ng progesterone / 10 mcl milk fat) set up for this assay were (1) pregnant and (1) nonpregnant (Day 20) and (.3) in estrus and (.3) not in estrus ( Day 0). Within the application for diagnosis of pregnancy, 81.4% were diagnosed correctly as pregnant while 96.3% were diagnosed correctly as not pregnant. The latter figure is somewhat lower than in the MPT (100%), but under the practical conditions the error lies within the range of false diagnosis due to problems with sample identification.     

Alternative complement pathway in bovine serum: lysis of human erythrocytes.

The hemolysis of unsensitized human erythrocytes by fresh bovine serums was investigated. Lysis occurred in ethylene glycol bis-amino tetraacetate buffers and with serums depleted of Clq. Serums extensively absorbed with packed human erythrocytes at 0 C effectively lysed human erythrocytes, but optimal lytic capacity required target cells "sensitized" with a heat-stable serum factor. Lysis did not occur with serums absorbed with zymosan at 17 C or heat inactivated at 50 C. These results indicate that human erythrocytes can activate the alternative pathway of complement in bovine serums. Lysis can proceed in the apparent absence of antibodies, although their presence may enhance the reaction.     

Tiering in suspension-feeding communities on soft substrata throughout the phanerozoic

Tiering of benthic marine suspension-feeding communities on soft substrata has varied throughout the Phanerozoic. Epifaunal tiering was most developed during the middle and late Paleozoic and the Triassic to Jurassic, with large-scale reductions in tiering occurring during the Permian-Triassic extinctions and after the Jurassic. Infaunal tiering reached its highest level of organization after the Paleozoic.