Mouse embryo cells cultured in vitro in serum-supplemented media undergo growth crisis, resulting in the loss of genomically normal cells prior to the appearance of established, aneuploid cell lines. Mouse embryo cells established and maintained for multiple passages in the absence of serum did not exhibit growth crisis or gross chromosomal aberration. Cells cultured under these conditions were dependent on epidermal growth factor for survival. Proliferation was reversibly inhibited by serum or platelet-free plasma, suggesting that mouse embryo cultures maintained by conventional procedures are under the influence of inhibitory factors.

Human serum spreading factor, an animal cell adhesion-promoting glycoprotein, bound Staphylococcus aureus in an assay in which association of bacteria to protein-precoated microtiter wells was quantitated. Interaction of human serum spreading factor with S. aureus suggests that this protein may play a role in host defenses and in the invasiveness and pathogenicity of microbial infections.

Semen characteristics and egg production of male and female commercial broiler breeders maintained in cages or on litter floors were evaluated over a 24-week period. Semen was collected from males caged singly or in pairs on a schedule of 3, 5, and 10 times (3X, 5X, and 10X) weekly from 36 through 59 weeks of age. Semen volume and concentration were determined once weekly for each male. Fertility and hatchability data of semen from males of the various treatment groups were obtained at 4 week intervals. Body weights and leg and foot problems were recorded at 28-day intervals and mortalities noted. No significant differences in semen volume, sperm concentration, percent fertility, and percent hatchability were found between males ejaculated 3X and 5X weekly or between males caged individually or as pairs. Total sperm per ejaculate was highest in birds ejaculated 5X weekly. Males ejaculated 10X weekly showed excessive cumulative mortality. The data suggest that although frequent semen collection (10X weekly) is feasible for up to 15 consecutive weeks, intensive use of males will be dependent upon proper management conditions.Broiler breeders, 36 through 59 weeks of age, were maintained on litter floors in groups based on male to female ratios of 1:25, 2:25, and 3:25 in individual pens. Fertility and hatchability data were obtained at 4 week intervals from hatching eggs produced by natural mating. Percent egg production, mortality, and female body weights at 28-day intervals were recorded. Percent fertility and hatchability were not significantly different among male to female ratios of 1:25, 2:25, and 3:25.

No abstract

Because of the scarcity of literature on the successful use of serological methods for differentiation of * Corresponding author. t Oregon Agricultural Experiment Station Technical Paper no. 6916.