Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Indian Ocean 1964

Mercator projection.; Shows configuration of ocean bottom by pictorial representation and indicated depths.; Scale ca. 1:10,000,000 at the Equator.Color;1:10,000,00

Subsurface studies of the Detroit River series

Master of ScienceGeologyUniversity of Michiganhttps://deepblue.lib.umich.edu/bitstream/2027.42/115412/2/39015003275073.pd

Imaging System for Monitoring Calcium Flux in Parabolic Flight

This year’s Boise State Microgravity University team is building a system which will excite osteocyte mono-cultures and osteocyte-osteoblast co-cultures with 350nm light and then image the emission for free calcium or bound calcium at 485nm and 405nm, respectively. In order to image these wavelengths, the system built needed enough resolution to image a 5mm diameter well of a microtiter 96 well plate and to differentiate between wells in close proximity since all 96 wells fit into a 3x5 inch area. This made imaging and image post processing difficult due to bleed over from one well to the next. Another complexity of the system is that it needed to image these wells during a 30s period of micro or hyper gravity, requiring the exposure time and time between captures to be small. The imager itself needed to be sensitive enough that it can capture the specific wavelengths without introducing unnecessary noise even though the signal will not have significant luminosity. The team used two different mono-chrome imagers using C-mount band-pass filters in order to isolate both 405nm and 485nm emissions simultaneously with one imager per wavelength. After capturing the images, post-processing will be performed utilizing digital image filtering and manipulation methods to determine how much luminosity from each well was caused by unbound or bound dye, allowing a quantification of free calcium. The team expects that, as with last year’s cells, there will be a definite correlation between the gravitational stress on the cells to the amount of free calcium in each well

Heezen-Tharp map and papers collection.

Consists of a wide variety of materials relating to an effort to map ocean floors carried out by the Lamont-Doherty Earth Science Observatory of Columbia University. This work was accomplished by geologist Bruce C. Heezen and oceanographer/cartographer Marie Tharp. The materials included maps, preliminary drawings, earth science data, precision depth recordings, scientific and technical reports, papers, correspondence, cruise logbooks, printing masters, reproducibles, and globes.Register in Geography and Map Division Reading Room

[Manuscript painting of Heezen-Tharp "World ocean floor" map by Berann].

Relief shown by land form drawings, shading, and gradient tints. Depths shown by land form drawings, shading, gradient tints, and soundings.Also covers land areas of the world.Title supplied by cataloger.Hand painted map by Heinrich C. Berann

Bone Cell Signaling in Parabolic Flight

Osteocytes integrate mechanical information into chemical signals relayed to osteoclast and osteoblast cell populations. In effect, these signals orchestrate bone resorption and formation by the osteoclasts and osteoblasts, respectively. While these activities are essential for the maintenance of healthy bone, imbalances in these processes by exposure to extreme environments, such as microgravity, are hypothesized to lead to highly detrimental bone loss. Changes in free calcium concentration, known as calcium flux, is an intermediate step in the chemical signaling processes of the osteoctyes. To determine how environments of continually alternating forces affect the bones of the human body, it is important to study how those environments affect calcium flux. To this end, this experiment examines how osteocyte and osteoblast mono- and co-cultures respond to the periods of micro-and hyper-gravity experienced onboard NASA’s Weightless Wonder. Calcium flux will be fluorescently monitored through the use of a lens and imaging-based system which will monitor a 96-well microtiter plate containing the cell cultures. From a previous study by the 2010-2011 BSU Microgravity University team, it is expected that cellular calcium concentrations will increase during periods of hyper-gravity and decrease during periods of microgravity