Life Sciences Commons^™

The Hairless-Obese Mouse, William D. Stansfield

Biological Sciences

Viable mice homozygous for two recessive autosomal genes, hairless (hr) and obese (ob) were produced with an average life span of 538 ± 34.1 days. On the average, hairless-obese mice weighed about 73 percent as much as obese mice. Since obese mice consumed approximately 73 percent as much oxygen per gram body weight per hour as hairless-obese mice at about 24°C, the weight averages appear to be closely inversely related to the oxygen consumption averages. The presence or absence of pelage seems to make a negligible contribution to oxygen consumption in these two types of obese …

Systematics Of Isocarpha (Compositae: Eupatorieae), David J. Keil, Tod F. Stuessy

Biological Sciences

Isocarpha comprises five species ranging from southern Texas and the Bahamas to northern Peru and northeastern Brazil. The genus belongs in Eupatorieae rather than Heliantheae, but structure of the head of Isocarpha with its elongate, chaffy receptacle is anomalous within Eupatorieae. An hypothesis is presented suggesting the evolutionary derivation of this type of head through formation of floral buds in the axils of the involucral bracts. Generic ties of Isocarpha within Eupatorieae are unclear, but the closest affinities appear to be with Ayapana and relatives.

The Pzc Of Mercury In The Presence Of Humic Acids And Their Complexes With Aluminium, Geraldine S.P. Ritchie, Alan M. Posner, Ian M. Ritchie

Food Science and Nutrition

Variation of the lifetime of a mercury drop with potential was used to determine the pzc of mercury in the presence of soil humic acids and their aluminium complexes. In all cases there was an overall net shift in the pzc in the cathodic direction. Variation in the extent of the shift with pH and concentration indicated greater adsorption of negatively charged species. The shift was smaller in the presence of aluminium humates, probably due to a decrease in the negative charge of the humic acid molecules after complexing. The use of electroanalytical techniques for metal speciation studies in soils …

Heat Tolerance Of Kentucky Bluegrasses, Perennial Ryegrasses, And Annual Bluegrass, David J. Wehner, T. L. Watschke

Office of the Dean (CAFES) Scholarship

Use of cool-season turfgrasses in transitional environments is limited, in part, by their heat tolerance. Development of a rapid heat tolerance screening technique would be of value in determining the potential of turf•grasses for use in warmer areas.

The heat tolerance of 22 Kentucky bluegrass (Poa pratensis L.) cultivars, Poa annua L., and four perennial ryegrass cultivars (Lolium perenne L.) was evaluated by exposing plants for 30 min to temperatures ranging from 41 to 49 C in single degree intervals. Ten-week-old plants, which had been grown under a low level of N fertilization and watered infrequently to maximize …