Abstract : We have developed a high-throughput miniature bioprocess array for the cultivation of microorganisms in a controlled, reproducible environment. The miniature bioprocess array is based on an array of 150-microliters wells, each one of which incorporates MEMS for the closed-loop control of cell culture parameters such as temperature, pH, and dissolved oxygen. The wells incorporate a suite of sensors, including interdigitated capacitors for cell density, thermopile temperature sensors, and oxygen sensors. Deep reactive-ion etched (DRIE) capacitive sensors enable new capabilities, such as the measurement of cell density in the bulk of the solution. Oxygen is generated by electrolysis, which also provides a means of mixing the solution in the well. Data acquisition, communication, and control will be implemented in foundry CMOS. A four-wire bus connects the electronic interface at each well to each other and to a battery, a clock serial input/output, and ground.
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Earthquakes and laboratory experience show that columns with inadequate transverse reinforcement are vulnerable to damage including shear and axial load failure. To study this behavior, four full-scale columns with light transverse reinforcement were tested quasistatically under unidirectional lateral load with either constant or varying axial loads. Test results show that responses of columns with nominally identical properties vary considerably with magnitude and history of axial and lateral loads. Observed behavior is compared with expected behavior based on available analytical models. The FEMA 356 assessment model predicted the column strengths well, but underestimated the displacements.
The original goal of this award was to develop a proteoglycan “chip” containing suitable oligosaccharides that could be used as substrates for glycosyltransferases involved in synthesis or proteoglycans in higher plant cell walls. We had previously developed a suite of cloned enzymes that could be used to cleave most of the relevant glycosidic linkages in plant cell walls. The next step, supported by the previous award and this award, was to produce a series of transgenic plants in which synthetic proteins were introduced that contained each of the known sequence motifs that induce prolyl hydroxylation, and subsequent glycosylation. This work was completed and published in Estevez et al (2006). We then engaged on a series of experiments to define the properties of the prolyl hydroxylases that convert certain prolyl resides to hydroxyproline for subsequent glycosylation. This proved to be a challenging goal that required recruitment of an international team of complementary skills and several additional years or research. However, the effort was successful and has been published in Science recenty (Velasquez et al., 2011). In the course of this project, the postdoc supported by the award (Jose Estevez) was asked to provide technical assistance to a colleague at Stanford because of his expertise in marine polysaccharides. This led to the important discovery that marine algae have compounds that could be classified as lignin (Martone et al., 2009). Publications supported by the award Estévez, J.M., Kieliszewski, M.J., Khitrov, N., Somerville, C. (2006) Characterization of synthetic hydroxyproline-rich proteoglycans with AGP- and extensin-motifs in Arabidopsis. Plant Physiol., 142,458-470 Martone, P.T., Estevez, J.M., Lu, F., Ruel, K., Ralph, J., Denny, M.W., Somerville, C.R. (2009) Discovery of lignin in seaweed reveals convergent evolution of cell-wall architecture. Curr. Biol., 19, 169-175 Velasquez, S.M., M. Ricardi, M.M., Dorosz, J.G., Fernandez, P.V., Nadra, A.D., Pol-Fachin, L., Egelund, J., Gille, S., Harholt, J., Ciancia, M., Verli, H., Pauly, M., Bacic, A., Olsen, C.E., r Ulvskov, P., Petersen, B.L., Somerville, C., Iusem, N.D. & Estevez, J.M. (2011) O-glycosylated cell wall proteins are essential in root hair growth. Science 332,1401-1403
Microbial biofilms impact economically important processes ranging from water treatment to nosocomial infections. Understanding their ecology is a key step in learning how to manipulate them. A feature that changed scientists' understanding of microbial biofilms was the discovery of their three-dimensional heterogeneous structure, which occurred primarily with the advent of the confocal laser scanning microscope (CLSM) (1). It was recognized that handling attached populations of cells prior to imaging would distort their structure, principally owing to shear forces at the air-liquid interface tearing the biofilm (2). Consequently, flow cells that facilitated nondestructive imaging of biofilms were developed by several groups.
