Introduction of ethoxy-resorufin-o-deethylase activity by halogenated aromatic hydrocarbons and polycyclic aromatic hydrocarbons in primary hepatocytes of the green frog (Rana esculenta)

In this study, we measured the ethoxy-resorufin-O-deethylase (EROD) activity in primary hepatocytes of the common green frog Rana esculenta as a biomarker for cytochrome P4501A induction. We exposed hepatocytes derived from male and female frogs to several halogenated aromatic hydrocarbons, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PCDF), polychlorinated biphenyls (PCB-126, PCB-118). and polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BaP), chrysene, anthracene, and pyrene. Exposure to PCB-118, anthracene, and pyrene, up to 1 μ M, did not induce EROD activity, whereas TCDD and PCDF induced EROD activity maximally. In our primary frog hepatocytes, exposure to chrysene and BaP resulted in median effective concentration values (EC50) in the high nM range (82-1035 nM). Exposure to TCDD, PCDF and PCB-126 resulted in EC50 values of 0.4 to 8, 0.07 to 0.7, and 3 to 133 nM, respectively, which is in the same range as EC50 values found in primary hepatocytes of birds. Compared to our frog hepatocytes, primary rat hepatocytes seem to be more sensitive to TCDD, chrysene. and BaP

Determination of Genes Involved in Hygienic Behavior in the Honey Bee, Apis mellifera

Honeybees are an integral part of the agricultural industry, especially in the Midwestern United States. Honeybees serve as pollinators of crops, an invaluable job of honeybees, as well as producers of honey. Diseases that kill members of the colony threaten honeybee colonies, and there are few options available to treat these diseases. Some honeybees exhibit a behavior—termed hygienic behavior—in which the bees clean out diseased brood from the hive, thus conferring a natural resistance to three diseases of bees: American foulbrood, chalkbrood, and varroa mite. However, it is not found in all colonies and only a certain number of honeybees contain this behavior in a given colony. This desirable behavior can be traced to genetics—meaning hygienic honeybees exhibit this behavior partly due to information they carry in their DNA (genetic material). We have undertaken a large genetic screen in cooperation with Dr. Marla Spivak of the Entomology department at the University of Minnesota. We have identified differences between genes in brains from hygienic honeybees vs. non-hygienic honeybees using a technique called microarray, and are now validating these differences using a secondary biochemical technique. Identifying specific genes that allow these bees to protect their colonies is a critical step towards implementing this behavior in unprotected honeybee colonies

Effect of infill pattern in Fused Filament Fabrication (FFF) 3D Printing on materials performance

Fused Filament Fabrication (FFF) is an Additive Manufacturing process popularized in the last decade due to its easiness of use and lower costs. However, despite its increasing popularity, the process itself has several gaps in knowledge, hindering further uses on more advanced objects. Also, the freedom of design allows significant variances in the printed parts, many influencing production and mechanical properties. This work studies the influences of the infill patterns in the mechanical response of printed parts. Using poly (lactic acid) (PLA), a widely used polymer in FFF process, the mechanical responses of parts printed with different infill patterns were analyzed. Rectilinear, Honeycomb, Triangle and Grid patterns were tested on impact resistance and tensile strength. Additionally, samples masses were measured and compared to the mechanical response. Results shown significant differences in the on tested properties. Tensile strength varied from 2.4 to 1.1 MPa, and impact resistance from 3.8 to 1.5 kJ/m² Also, measured mass was found to be significantly higher on the Honeycomb pattern. Considering mechanical response from both tensile and impact tests along with printed mass, Rectilinear pattern can be considered the most advantageous from the economic point of view