Friday, October 25, 2013

Chemically Defined Medium as a Set Standard for Growth of Leuconostoc

Leuconostoc is a non-pathogenic, aero-tolerant anaerobic bacterial genus that lives on vegetation.
Leuconostoc plays an important role in industrial and food fermentations. Leuconostoc is often used for physiological and genetic studies related to polymer production.  Typically, a complex nutrient source comprised of beef and yeast extracts is used to support the growth of Leuconostoc, however, the exact chemical composition of the nutrient source remains uncertain and therefore may result in less desirable growth patterns than a defined nutrient source.  WIU undergraduate student, Megan McGlone has risen to the challenge for her undergraduate honors research project to determine if a defined nutrient source can serve as a suitable alternative to a complex nutrient source for growth of Leuconostoc.  To accomplish the research goal, Megan will cultivate Leuconostoc species for 12 hours in a defined nutrient source and a complex nutrient source. Bacterial growth in each nutrient source will be determined through two methods called viable plate count (quantitative) and spectrophotometry (qualitative). Growth rates (m h-1) and bacterial colonies formed per milliliter of culture broth (CFU/ml) will be calculated from the quantitative viable plate count. Spectrophotometry will be used as a real-time growth assessment to monitor the progress of each growth experiment. Data indicating that there is no statistical difference in growth between each nutrient source would support the use of defined as a suitable alternative to complex. In addition, data indicating an increase in growth for the defined would also support its use as an alternative to complex.  Megan's research advisor is Dr. Scott Holt.

Friday, August 23, 2013

Do Reduced Parasite Loads Contribute to Higher Abundances of Deer Mice?

Jonathan working overtime in the lab

Parasites are known to harm their hosts as they derive benefit, but are they capable of influencing the density and dynamics of their host populations?  Deer mice (Peromyscus maniculatus) are known to increase in abundance 2-5 times after a fire, but explanations for this increase remained unknown.  WIU graduate student, Jonathan Vaughn recently completed a study to investigate whether parasite load may be a factor to explain increased abundance of deer mice in post-burned forest.  Jonathan conducted an exhaustive survey for all ectoparasites (fleas, ticks and lice) and endoparasites (i.e., nematodes and cestodes) of specimens collected from a burned and unburned area of forest in western Montana.  Although no significant difference was found between the endoparasites from the two areas, the mean abundance of ectoparasites was lower in burned forest than unburned forest, especially for fleas, which exhibited a 70% reduction.  It’s possible that the improved healthy condition of deer mice from burned forest results in increases in abundance relative to their more heavily parasitized brethren from the unburned forest.   This study was conducted in collaboration with Rafal Zwolak and Sylwia Dziemian of the Adam Mickiewicz University (Poland) and Elizabeth Crone of Harvard Forest, Harvard University and under the guidance and mentorship of Jonathan’s graduate advisor, Dr. Shawn Meagher.   Jonathan has recently graduated and accepted a position as adjunct faculty at the WIU School of Agriculture.
A female flea, Aetheca wagneri

Sunday, April 21, 2013

Fungal Communities in Bats at Risk of White-Nose Syndrome in Caves and Mines in Southern Illinois

Indiana bat with white-nosed syndrome

Tabitha Williams
     WIU graduate student, Tabitha Williams recently conducted a study in an attempt to identify, characterize and compare psychrophilic fungal communities associated with seven different bat species commonly found in southern Illinois.  The purpose of the study is to provide important base-line data for bats, which live in caves that have not yet been infected with a relatively new and emerging fungus Geomyces destructans, which causes white-nose syndrome.  White-nose syndrome infects hibernating bats and has been responsible for major declines of bat populations in eastern North America due to an increase in frequency of arousals from torpor during hibernation leading to depletion of the fat reserves and subsequent starvation.  Using the genetic ITS rDNA barcode, fungal communities in southern Illinois were found to be dominated mostly by Ascomycota, followed by Zygomycota, and Basidomycota.  Nineteen isolates were identified as Geomyces strains with a high genetic similarity to G. destructans.   Most studies only examine bats in caves after they have been infected with G. destructans, but it is important to understand fungal community structure before bats are infected to provide a framework for how communities are altered after infection.  This study was conducted in collaboration with Robert McCleery of the University of Florida and Rod McClanahan of the United States Forest Service, Shawnee National Forest and under the guidance and and mentorship of Tabitha’s graduate advisor, Andrea Porras-Alfaro.

Friday, April 19, 2013

Forest Bee Diversity in Relation to Habitat and Vertical Stratification

Augochlora pura, an abundant species

       Many studies in tropical rain forests have shown that insect diversity in the canopy can differ markedly from diversity in the understory.  Surprisingly, relatively few studies have explored such diversity in temperate deciduous forests.  WIU graduate student, Jared Ruholl recently completed a study investigating differences in bee species composition between the canopy and in the understory and between early successional and oak/hickory Midwestern forest habitats.  He and his collaborator James Zweep, an undergraduate honors student,  collected 4,611 bee specimens comprised of 76 species.  Agapostemon virescens, Lasioglossum macoupinense, and L. smilacinae were associated with oak’/hickory understory, while Certina calcarata and L. versatum were associated with oak/hickory canopy.  This study is the first to document that bee diversity in Midwestern deciduous forests exhibits substantial spatial variation.  This study was conducted under the guidance and mentorship of Jared’s graduate advisor, Dr. Kenneth McCravy.
Jared Ruholl working with two  undergraduate students, Angela Walker (left) and Jamela Thompson (right)