Validation of a Fluorescence-Based Bacteria Enumeration and Viability Determination Method Using Image Cytometry

Craft beer production in the United States has been increasing significantly in recent years. As production and participation in the industry increases, so have consumer demands for more beer options. Breweries have met this call with experimentation of ingredients in their beer and also the styles they brew. One such beer, the sour beer, is an example of this experimentation and new product development. Sour beers are a style that differ from most other beers by how they are manufactured. Instead of being fermented with only yeast, both a lactic acid-producing bacteria and yeast are used. With increased competition amongst breweries and demand for consistent beer, new methods have been and are being developed to aid in quality control. Recent research has focused on the monitoring of yeast during fermentation enabled by fast and accurate assays, but there is a need for this same level of monitoring for bacteria in fermentation. In consideration of this, a method was developed to monitor lactobacilli concentration in a kettle sour environment, which may improve the production efficiency and consistency of kettle sour beers. This study developed counting methods using the fluorescent stains Syto BC and Syto 9 with image-based cytometry using three lactobacilli strains: L. plantarum, L. bulgaricus, and L. brevis. A method for viability determination was also evaluated in this study. These Lactobacilli species were grown and concentrations were compared using image cytometry with fluorescent stain and cultural enumeration. This procedure was completed in vitro at different dilutions and in a kettle sour environment at different time points. Results indicated that the method developed using fluorescence-based image cytometry to evaluate Lactobacillus spp. concentration is comparable to the standard method of plating in both a controlled setting and in a kettle sour fermentation. The objective for validation of a viability determination method using fluorescence-based image cytometry was not met in this study and requires future work. While the Cellometer X2 was able to provide total and dead bacteria counts, the data was inconsistent and deviated from plate counts significantly in the lower viability ranges. Determination of why the data did not line up with expected viabilities is an opportunity for further work. The use of the method described herein offer brewers a much faster means for analyzing lactobacilli concentration in soured wort. This not only will provide an opportunity to control the growth in kettle sour beer production, but also allow for the production of a standardized product due to the availability of near instantaneous information for quality control, greatly reducing potential for batch-to-batch variability

The ERK MAP Kinase Cascade Mediates Tail Swelling and a Protective Response to Rectal Infection in C. elegans

AbstractThe nematode Caenorhabditis elegans is proving to be an attractive model organism for investigating innate immune responses to infection [1]. Among the known pathogens of C. elegans is the bacterium Microbacterium nematophilum, which adheres to the nematode rectum and postanal cuticle, inducing swelling of the underlying hypodermal tissue and causing mild constipation [2]. We find that on infection by M. nematophilum, an extracellular signal-regulated kinase (ERK) mitogen-activated protein (MAP) kinase cascade mediates tail swelling and protects C. elegans from severe constipation, which would otherwise arrest development and cause sterility. Involvement in pathogen defense represents a new role for ERK MAP kinase signaling in this organism

Direct Detection of Galactic Halo Dark Matter

The Milky Way Galaxy contains a large, spherical component which is believed to harbor a substantial amount of unseen matter. Recent observations indirectly suggest that as much as half of this ``dark matter'' may be in the form of old, very cool white dwarfs, the remnants of an ancient population of stars as old as the Galaxy itself. We conducted a survey to find faint, cool white dwarfs with large space velocities, indicative of their membership in the Galaxy's spherical halo component. The survey reveals a substantial, directly observed population of old white dwarfs, too faint to be seen in previous surveys. This newly discovered population accounts for at least 2% of the halo dark matter. It provides a natural explanation for the indirect observations, and represents a direct detection of Galactic halo dark matter.Comment: 13 pages, 4 figures, 1 table. Note added after Science Express online publication: This text reflects the correction of a few typographical errors in the online version of the table. It also includes the new constraint on the calculation of d_max which accounts for the fact that the survey could not have detected stars with proper motions below 0.33 arcseconds per year. Published online at ScienceExpress www.sciencemag.org 22 March 2001; 10.1126/science.1059954; To appear in Science 27 April 200

What about the men? Perinatal experiences of men of color whose partners were at risk for preterm birth, a qualitative study.

BACKGROUND:Preterm birth in the United States is associated with maternal clinical factors such as diabetes, hypertension and social factors including race, ethnicity, and socioeconomic status. In California, 8.7% of all live births are preterm, with African American and Black families experiencing the greatest burden. The impact of paternal factors on birth outcomes has been studied, but little is known about the experience of men of color (MOC). The purpose of this study was to explore the experiences of MOC who are partners to women at medical and social risk for preterm birth. METHODS:This study used a qualitative research design and focus group methods. The research was embedded within an existing study exploring experiences of women of color at risk for preterm birth conducted by the California Preterm Birth Initiative. RESULTS:Twelve MOC participated in the study and among them had 9 preterm children. Four themes emerged from thematic analysis of men's experiences: (1) "Being the Rock": Providing comfort and security; (2) "It's a blessing all the way around": Keeping faith during uncertainty; (3) "Tell me EVERYTHING": Unmet needs during pregnancy and delivery; (4) "Like a guinea pig": Frustration with the healthcare system. Participants identified many barriers to having a healthy pregnancy and birth including inadequate support for decision making, differential treatment, and discrimination. CONCLUSIONS:This study shows novel and shared narratives regarding MOC experiences during pregnancy, birth, and postpartum periods. Healthcare providers have an essential role to acknowledge MOC, their experience of discrimination and mistrust, and to assess needs for support that can improve birth outcomes. As MOC and their families are at especially high social and medical risk for preterm birth, their voice and experience should be central in all future research on this topic

Brown Dwarfs in the Pleiades Cluster. III. A deep IZ survey

We present the results of a deep CCD-based IZ photometric survey of a ~1 sq. deg area in the central region of the Pleiades Galactic open cluster. The magnitude coverage of our survey (from I~17.5 down to 22) allows us to detect substellar candidates with masses between 0.075 and 0.03 Msol. Details of the photometric reduction and selection criteria are given. Finder charts prepared from the I-band images are provided.Comment: 11 pages with 8 figures, 4 of them are finder charts given in gif format. Accepted for publication in A&AS. Also available at http://www.iac.es/publicaciones/preprints.htm