A survey of the aerobic bacteria in the feces of captive raptors

Feces of 47 captive raptors belonging to the order Falconiformes or Strigiformes were cultured for bacteria. Gram-negative bacteria, which were cultured from the feces of 45 of the 47 raptors, were the most common isolates. A wide variety of species were identified, including a newly described genus (Moellerella wisconsensis), two newly described species (Escherichia fergusonii and Proteus penneri), and a member of a newly described enteric group (CDC Enteric group 41). Additional organisms identified that have not been reported in previous bacteriological surveys of raptors were Salmonella heidelberg, Salmonella braenderup, Morganella morganii, Yersinia ruckeri, Serratia spp., and Kluyvera sp. Escherichia coli, isolated from the feces of 42 of the 47 raptors, was the most frequently recovered. Streptococcus faecalis, the second most common isolate, was cultured from 30 birds. Several differences were observed between fecal bacteria isolated from raptors fed commercially prepared chicken and those isolated from raptors not fed chicken. The most obvious difference was that birds fed chicken had more varied gram-negative bacterial species and in greater numbers per fecal sample. The potential for the isolated bacteria from raptors as pathogens in humans and avian species is discussed.     

A mathematical model of the United States beef production system

Dynamic linear programming was used to model the US beef production system, to determine the cattle cycle effects on feeder cattle supplies and to select feeding options that would maximise USDA choice and prime quality grade beef production. The model represented the US as a five-region beef production system with inter-regional transportation of offspring for feeding purposes. Cow weights, offspring weaning weights and feed efficiency were different for each region, but the feeding activities were the same in each region except for region two. In region two the feeding of grain to steer and heifer offspring was not an industry practice. Dynamic properties of the model were achieved through constraints that transferred animals from year zero (initial condition) to year five using calving, cow culling, replacement heifer and death loss rates as controlling parameters. The results of model exercises that used historical parameter values indicate that there will be a significant decrease in the supply of beef at all grade levels over the next five years. They also suggest that it is more economically efficient to feed calves from the southeastern and northern parts of the USA if they are transported to the southwestern region.     

Methane formation in living trees: a microbial origin

Visibly healthy hardwood trees located on poorly drained soils contained high pressures of methane. Heartwood from these trees was water-soaked, neutral to alkaline in pH, fetid in odor, and infested with a diverse population of obligately anaerobic bacteria. the bacterium responsible for methane formation in tree. was isolated and characterized as a member of the genus Methanobacterium.     

Mouse hepatoblastomas: a histologic, ultrastructural, and immunohistochemical study

Hepatoblastomas from B6C3F1 and BALB/c mice were examined by light and electron microscopy and by immunohistochemical reactions for alpha-fetoprotein, keratin, and vimentin. Tumors occurred in one group of a chronic bioassay for the interaction of diet, genetic strain, and the carcinogen, 2-acetylaminofluorene. Tumors had several populations (including epithelial and mesenchymal cells) in various stages of differentiation. Neoplastic epithelial cells had features of embryonal hepatocytes, such as sparse cytoplasmic organelles, absence of glycogen, abundant free ribosomes, occasional bile canaliculi, and peroxisome-like dense bodies. Embryonal fibroblast-like cells had pleomorphic and folded nuclei with prominent perinuclear chromatin and dispersed cytoplasmic organelles. Fibroblast-like cells were surrounded by bundles of collagen fibrils. Intermediate or transitional types of cells were seen. No tumor cells were immunoreactive for mouse alpha-fetoprotein (AFP) antibody, unlike those in hepatocellular adenomas or carcinomas. Epithelial and mesenchymal tumor cells contained intermediate filaments throughout the cytoplasm; some of these cells stained for keratin but not for vimentin. These findings suggest that mouse hepatoblastomas are derived from bipotential liver blastema cells and are composed of a mixture of several cell populations.     

Increased levels of DNA synthesis in hyperplastic renal tubules of aging nephropathy in female F344/NCr rats

Histoautoradiography was done to evaluate cell turnover by measuring levels of DNA synthesis in the different anatomic areas of the kidney in aging (76 to 103 weeks of age) female F344/NCr rats after injection of tritiated thymidine (3H-thymidine). All areas showed increased 3H-thymidine labeling indices (LI), including cortical and medullary tubules and interstitium. The extent of increase was directly correlated with increasing severity of the nephropathy. Atrophic, degenerative, and hyperplastic cortical tubules in areas of nephropathy had LI eight to nine times greater than nonaffected areas and more normal kidneys. These observations suggest that the hyperplastic responses of renal tubules to the unknown etiologic agents of aging nephropathy may be similar to those of tubules responding to chemical toxins.