James L. Carmon

Response of Wild Rodents to Acute Gamma Radiation

Recent reports have shown that some species of small wild rodents, pocket mice (Perognathus longimembris and Perognathus formosus) (1) and cotton rats (Sigmodon hispidus) (2), given an acute dose of y-radiation have an LD50o(3o) that ranges between 1200 and 1500 r. This level of lethality is considerably higher than that of the laboratory mouse (544 to 665 r) (3) and the laboratory rat (665 r) (4), animals of approximately the same body size as the pocket mouse and cotton rat. Since it has been suggested that resistance to radiation is a criterion of general fitness (5), it might be concluded that wild rodents that are genetically diverse and as adults have passed through a period of rigorous natural selection are more fit and also more resistant than laboratory rodents. Alternatively, these data may represent exceptional species. Our studies have been designed to obtain evidence on these questions of comparative radiation sensitivity. Since a large number of variables such as age, sex, kind and intensity of radiation, previous treatment, length of time in captivity, genetic background, and environment affect lethality and make comparison of the results from different experiments and laboratories difficult, the procedure in these studies has been to collect adult wild small mammals by live-trapping and to compare their response to acute y-radiation with that of domestic mice under both laboratory and field conditions. Where possible, both wild and domestic forms of the same species have been used. In the laboratory experiments the wild mammals must adjust to the unusually stabile laboratory environment; in the field experiments the domestic mammals must adjust to a constantly fluctuating environment. Thus, the experimental design compares wild and domestic forms within a species and between

Pelage Color Polymorphism in Peromyscus polionotus

In addition to the normal dark brown old-field mice, a pale brown phenotype occurs on the Savannah River Plant in South Carolina. A linear model can be used to describe the reflectance spectrum of the dorsal pelage of the two color variants. The reflectance spectrum of pale brown adults had a higher intercept and slope than the darker adults. The paler mice occurred in high frequency only on the lighter, Lakeland Sand soils. Pleiotrophic effects of the autosomal pale brown gene were noted in reproductive performance in the laboratory, trappable life span, and number of captures per unit time, but not in the growth rate of the two variants. Under field conditions, presence or absence of supplementary food also modifies the expression of the phenotype. The complex interaction of genetic and environmental factors and inadequate knowledge about the environment of the two phenotypes makes their distribution difficult to interpret. It is apparent, however, that the simple hypothesis of predators selecting mice that contrast with their background is not sufficient to explain all of the data.

Influence of High Environmental Temperature on Fertility and Hatchability of Eggs of Domestic Fowl

C OMPARATIVELY little information has been published to indicate the effect of high environmental temperatures on fertility and hatchability in chickens. Upp and Thompson (1927), Funk (1935), and Hewang (1944) reported that fertility and hatchability decreased during the hot summer months. Wilson (1949) showed that fertility in the female was not seriously affected by high temperatures. It has been demonstrated by others, however, that the fertilizing capacity of the cock declines during hot weather (Parker and McSpadden, 1943; Huston and Wheeler, 1949). Ota, McNally, and Wilson (1955) found that fertility was reduced in a variable environment and that fertility and hatchability were improved by keeping the hens at a constant temperature of 65. F. The experiment reported here was designed to study the fertility and hatchability of eggs of fowl exposed continuously from time of hatch through the laying year to a controlled high environmental temperature.

A discriminant function index for information system evaluation

A Discriminant Function Index is proposed for use in the evaluation of information storage and retrieval systems which takes into account the interdependencies between the measured variables and the relative value placed on these variables by the system evaluator. The single number which results, the Index, is proportional to the true value of the individual information system and provides a means of comparing components of individual systems or independent systems. The proposed index is of the form I =b1x1 + b2x2 + b3x3 +…+ bnxn where the xi are measured variables of system performance (e.g., precision, recall, rank recall, log precision, cost, etc.) and the bi take values that will maximize the correlation, rIG, between the index, I, and the true value of the system, G. The prediction of G from the variables is obtained through multiple regression techniques. Application of the index is illustrated through use of data reported in the literature.

INFLUENCE OF TEMPERATURE ON THE SUSCEPTIBILITY OF THE OLD-FIELD MOUSE (PEROMYSCUS POLIONOTUS) TO ACUTE RADIATION.

The

Breed Differences in Egg Production of Domestic Fowl Held at High Environmental Temperatures

{\rm LD}_{50(30)}

The Influence of High Environmental Temperature on Thyroid Size of Domestic Fowl

was 1147 ± 15 R for the old-field mouse, Peromyscus polionotus. Radioresistance, as measured by this value, was not affected by sex or temperature over the range of 16° to 32° C. The variance of the

Studies on the Cholesterol Content of Eggs from Various Breeds and/or Strains of Chickens

{\rm LD}_{50(30)}

REPRODUCTIVE PERFORMANCE OF A LABORATORY COLONY OF PEROMYSCUS POLIONOTUS.

for the 16° C group was significantly higher than that of the other two groups. The time until death after irradiation of the mice that died within 30 days was significantly affected by temperature and radiation level, and their interaction, but not by sex.