Abnormal bone development and lameness associated with secondary copper deficiency in young cattle

Lameness in a group of 5- to 12-month-old calves was found to be clinically, radiographically, and pathologically associated with abnormal bone development of the distal growth plates of the metacarpus and metatarsus. Copper concentrations in serum and liver were low. Serum calcium, phosphorus, and alkaline phosphatase values were normal. In pasture forage samples, sulfate, zinc, and molybdenum concentrations were high, whereas copper, calcium, and phosphorus concentrations were normal. Red blood cell (RBC) counts and hemoglobin values were within normal limits. Radiographic findings included a widened zone of cartilage and lipping of the medial and lateral areas of the physeal plate. Histologic findings included focal widenings of the growth plate consisting of tongues of uncalcified cartilage.

Genetic control of radiation sensitivity in Schizosaccharomyces pombe

Genetic analysis of a large number of radiation-sensitive mutants of S. pombe, isolated in different laboratories, showed that these isolates represent 22 non-allelic loci. The mutants were shown to fall into three distinct classes concerning response to UV and ionizing radiation, including two mutants which are primarily sensitive to ionizing radiation but not to UV. Single-gene mutants were crossed to obtain supersensitive double mutants. Such double mutants showed a marked increase in sensitivty to a variety of inactivating agents as compared to the parental strains. The isolation of three classes of radiation-sensitive mutants and the construction of double mutants implies the presence of multiple pathways in S. pombe for repair of radiation-induced damage. The bearing of these data on cellular repair mechanisms in eukaryotes is discussed.

Prediction of carcass fat from body measurements made on live rats differing in age, sex and strain

1. Individual body fat and body measurements such as lengths, girths and selected skinfold thicknesses were determined in our laboratory strain (BHE), a highly inbred strain (IN) of BHE rats and in a strain of Wistar rats. Measurements were made on unconscious rats in less than 5 min per rat just before autopsy; body fat content was determined in individual rats of both sexes at 50, 100 and 300 days of age.

2. Among the strains, mean total body fat was highest in BHE rats at each age; IN rats of similar average body size were leanest. Statistically significant differences in body fat among the strains were due primarily to differences among the male rats at 300 days. Total protein and skeletal mass increased with increases in age and body size, as did body fat in rats after maturity. IN rats had the largest fat-free weights. Although significant age differences in body fat and body measurements occurred, they were in part dependent upon changes in body- weight, sex and strain of the animals. Female rats had more fat per unit body-weight than males at each age studied. Females, though fatter than males, had smaller skinfold thicknesses, indi- cating that female fat increases are primarily in visceral fat.

3. Large variation in fat among individuals within strains of the same body-weight and age suggests a genetic influence in fat potential in rats not associated with age or body-weight.

4. Results from multiple regression analyses showed differences among adjusted means and partial regression coefficients due to strain and sex of the animals. Although final body-weight was the predictor common to all equations, body length, abdominal girth and subscapular skinfold were common to all but one set of equations. Chest girth, tibia length, triceps and abdominal skinfolds decreased in frequency of appearance in that order. Some of the measurements were more effective predictors at one age than at another. It was clearly necessary to take into account body dimensions other than weight to obtain an optimal prediction of body fat.

5. Differences in characteristics of the rats support the concept of genetic influences in fat deposition in individuals and indicate the complex nature of these influences.