Zone Precipitation Chromatography: Its Use in the Isolation of Different Collagen Types

Zone Precipitation Chromatography is useful tech-nique for the initial isolation of the different colla-gen types in their native configuration. Small quan-tities of collagen mixtures can be rapidly separated into different collagen types with relatively high degree of purity, based upon stained protein patterns on sodium dodecyl sulfate polyacrylamide gel electro-phoresis (SDS-PAGE) slab gels. Tn the commonly used bulk salt preparative method for isolating the different collagens, 50 mg of starting material was needed. Three days were required to complete the procedure. The stained protein patterns on SDS-PAGE slab gels showed about 25% contamination with the bulk purified Type III fraction and 20% contamination with the bulk purified type AB collagen. With Zone Precipitation Chromatography 5 mg of starting material was used and in less than 4 hours the mixture was separated with Types III and AB fractions showing less than 10% contamination from other collagen types. The technique is patterned after the Zone Precinitation method reported by Porath seventeen years ago and utilizes a step-wise sodium chloride gradient to precipitate and redissolve the collagens, eluting from the interbead spaces of a molecular sieve column.     

Ecology and the War on Hunger

This interdisciplinary activity promotes science, technology, and language arts and is well suited for upper elementary grade students. In the activity, students' research about a teacher-assigned weather phenomenon facilitates their study of the weather. When they have completed their research, students word process a paper summarizing their findings and generate graphical representations of a weather phenomenon using Microsoft Paint software. The paper and the computer-generated graphical representation measure learning and provide insight into the level of student understanding that other assessment tools, such as quizzes, tests, and questioning techniques, do not provide.     

Book review

Biomineralization and Biological Metal Accumulation: Biological and Geological Perspectives. Papers presented at the Fourth International Symposium on Biomineralization, Renesse, The Netherlands, June 2–5, 1982. P. Westbroek and E. W. De Jong, eds. R. Reidel Publishing Company, Dodrecht, the Netherlands; Boston, U.S.A.; and London, England. 1983, 533 pp, $69.50.     

Experience of violence and socioeconomic position in South Africa: a national study

Background

Violence is a leading cause of morbidity and mortality in South Africa and needs to be researched from a public health perspective. Typically in violence research, socioeconomic position is used in the analysis to control for confounding. Social epidemiology approaches this variable as a primary determinant of interest and is used in this research to better understand the aetiology of violence in South Africa. We hypothesised that measures of socioeconomic position (employment, education and household wealth) would be inversely related to violence at the individual and household levels.

Methodology/Principal Findings

Data came from the1998 South African Demographic and Health Survey (SADHS). Measures of socioeconomic position used were employment, education and household wealth. Eighty-eight people (0.2%) received treatment for a violent injury in the previous 30 days and 103 households (0.9%) experienced a violent death in the previous year. Risk factors for violence at the individual level included employment (41% of those who experienced violence were employed vs. 27% of those who did not, p = 0.02), and education (those who experienced violence had on average, one year more education than those who did not, p = 0.04). Belonging to a household in the wealthiest quintile was protective against violence (OR: 0.32; 95% CI: 0.12–0.89). In contrast, at the household level all three measures of socioeconomic position were protective against the experience of a violent death. The only association to persist in the multivariate analysis was that between the wealth of the household and violence at the individual level.

Conclusions/Significance

Our hypothesis was supported if household wealth was used as the measure of socioeconomic position at the individual level. While more research is needed to inform the conflicting results observed between the individual and household levels, this analysis has begun to identify the disparities across the socioeconomic structure with respect to violent outcomes.     

Adult emergence phenology in checkerspot butterflies: the effects of macroclimate,topoclimate, and population history

The prediction of adult emergence times in insect populations can be greatly complicated by microclimatic gradients, especially in circumstances where distributions of juveniles along those gradients vary from year to year. To investigate adult emergence patterns in topographically heterogeneous habitats, we built a model of postdiapause development of the Bay checkerspot butterfly, Euphydryas editha bayensis. The model uses slope-specific insolation as the rate-controlling variable, and accounts for both solar exposure of the habitat and cloud cover. Instar-specific larval mass gains per unit of insolation were determined from mark-recapture experiments. A small correction for daily low temperatures was used to calibrate the model to five years of field data on larval mass. The model predicted mean mass of 90% of larval samples within 4 clear days over a 70–120 day growing season. The magnitude of spatial variation in emergence times across habitat slopes is greater than annual variation in emergence times due to yearly weather conditions. Historical variation (yearly shifts in larval distributions across slopes) is an important determinant of mean population emergence dates. All of these factors need to be considered in understanding adult emergence phenology in this butterfly and in other insects inhabiting heterogeneous thermal environments. Such an understanding can be useful in managing insect populations for both pest control and conservation.