An aeroponic culture system for the study of root herbivory on Arabidopsis thaliana

<p>Abstract</p> <p>Background</p> <p>Plant defense against herbivory has been studied primarily in aerial tissues. However, complex defense mechanisms have evolved in all parts of the plant to combat herbivore attack and these mechanisms are likely to differ in the aerial and subterranean environment. Research investigating defense responses belowground has been hindered by experimental difficulties associated with the accessibility and quality of root tissue and the lack of bioassays using model plants with altered defense profiles.</p> <p>Results</p> <p>We have developed an aeroponic culture system based on a calcined clay substrate that allows insect herbivores to feed on plant roots while providing easy recovery of the root tissue. The culture method was validated by a root-herbivore system developed for <it>Arabidopsis thaliana </it>and the herbivore <it>Bradysia </it>spp. (fungus gnat)<it>. Arabidopsis </it>root mass obtained from aeroponically grown plants was comparable to that from other culture systems, and the plants were morphologically normal. <it>Bradysia </it>larvae caused considerable root damage resulting in reduced root biomass and water absorption. After feeding on the aeroponically grown root tissue, the larvae pupated and emerged as adults. Root damage of mature plants cultivated in aeroponic substrate was compared to that of <it>Arabidopsis </it>seedlings grown in potting mix. Seedlings were notably more susceptible to <it>Bradysia </it>feeding than mature plants and showed decreased overall growth and survival rates.</p> <p>Conclusions</p> <p>A root-herbivore system consisting of <it>Arabidopsis thaliana </it>and larvae of the opportunistic herbivore <it>Bradysia </it>spp. has been established that mimics herbivory in the rhizosphere. <it>Bradysia </it>infestation of <it>Arabidopsis </it>grown in this culture system significantly affects plant performance. The culture method will allow simple profiling and <it>in vivo </it>functional analysis of root defenses such as chemical defense metabolites that are released in response to belowground insect attack.</p

Cell Growth Paramenters and Sister Chromatid Exchange Level in Fibroblasts from a Patient Diagnosed with Bloom Syndrome

v, 77 leaves. Advisor: Michael E. MyszewskiThe problem. A patient, KB, diagnosed with the autosomal recessive genetic disorder Bloom Syndrome on the basis of clinical features, had failed to display the characteristic cytogenetic features of the syndrome. This research compared the growth response to bovine pituitary fibroblast growth factor, the mitotic index, and the sister chromatid exchange level of the KB fibroblasts with normal and known Bloom Syndrome control fibroblasts. Procedure. The growth responses of the KB, normal, and Bloom Syndrome cell lines to fibroblast qrowth factor were determined by culturing the fibroblasts over a seven-day period in the presence of three concentrations of fibroblast growth factor in medium supplemented with two levels of fetal bovine serum. Cell concentrations were measured at regular intervals over the culture period using a Coulter counter. Sister chromatid exchange levels were determined by culturing the fibroblasts for 72 hours in medium supplemented with the thymidine analog 5-bromo-2'- deoxyuridine. Following culture, cells were harvested and stained for differentiation of the sister chromatids using a fluorescence plus Giemsa technique, A mitotic index for each cell line was determined by counting the number of cells in division per 1000 cells on the slides prepared for sister chromatid exchange analysis. Findings. Like the normal cells, the KB fibroblasts utilized fibroblast growth factor for growth based on measurements of the population doubling time in the first 48 hours of culture. Unlike either of the control cell lines, however, the KB fibroblasts exhibited no response to fibroblast growth factor as measured by maximum cell concentration attained. The mitocic index for the KB cell line was considerably lower than that determined for either control line. The sister chromatid exchange level seen in the KB fibroblasts corresponded with that seen in the normal control fibrobLasts and was unlike the elevated level seen in the Bloom Syndrome cells. Conclusion. The diagnosis of Bloom Syndrome in the patient, KB, is not supported an the basis of the growth responses of the patient's fibroblasts to fibroblast growth factor, the mitotic index, and the sister chromatid exchange rate

Travel and Parking Behavior in the United States

This paper looks at the connection between the regulation of parking by cities, transit service levels, and travel and parking behavior in the United States. Travel behavior information comes from the 1990 Nationwide Personal Transportation Survey (NPTS) and the Federal Urban Mass Transportation Administration’s 1990 Section 15 Report. Data on the current state of parking programs in place in central business districts of the U.S. is identified through telephone interviews of local officials responsible for parking policies from the twenty cities identified in the NPTS. The travel behavior analyses and the data from the parking officials interviews were combined with data from the Federal Highway Administration’s Journey-to-Work data to group cities according to their parking policies, transit service, and ridership levels on a continuum of “Transit-Accommodating Cities” and “Auto-Accomodating Cities”. A key finding is that cities with interventionist parking policies, high parking prices and limited supply, frequent transit service, and a high probability that travelers will pay to park are the most likely to have high transit ridership figures

THE IN VITRO DIFFERENTIATION OF MONONUCLEAR PHAGOCYTES : IV. THE ULTRASTRUCTURE OF MACROPHAGE DIFFERENTIATION IN THE PERITONEAL CAVITY AND IN CULTURE

The structure of unstimulated mouse peritoneal phagocytes has been examined by electron microscopy and compared to cells obtained from the inflamed peritoneum and from cultures maintained in vitro. The unstimulated cell resembles the blood monocyte and contains a moderate amount of rough surfaced endoplasmic reticulum, a small but well defined Golgi apparatus and a few, small, electron-opaque granules in the cytoplasm. During in vitro cultivation there are marked changes in cell ultrastructure. Most prominent is the formation of large electron-opaque granules, some of which have a complex matrix containing both electron-opaque and lucent vesicles. In addition, there is an increase in size of the Golgi apparatus with the appearance of new lamellae and tiny, smooth surfaced vesicles. With continued cultivation, large lipid droplets are found in apposition to the rough endoplasmic reticulum. The formation and size of electron-opaque granules as well as the enlargement of the Golgi region is stimulated by high concentrations of serum in the medium. Cells obtained from the peritoneal cavity of lipopolysaccharide stimulated animals demonstrated changes in ultrastructure similar to those seen in cells cultured in vitro