Now showing 1 - 5 of 535
- ItemCHARACTERIZATION OF MORPHOLOGICAL CHANGES IN ACTIVATED NEUTROPHILS(2005-05) DaSilva, Rhonda; Hood College Biology; Biomedical and Environmental ScienceNeutrophils leave the vasculature and migrate along a chemotactic gradient to an infectious focus where they ingest invading microorganisms. To accomplish this myriad of functions, neutrophils undergo considerable morphological changes. Treatment of neutrophils with the chemotactic peptide, formyl-methionyl-leucyl-phenylalanine (fMLF), 5 x 10(-9) M, results in a change in cellular morphology that includes formation of agranular projections and polarization of the cell. As determined by flow cytometric analysis these morphological change occurs within 5 min, peaks by 30 min, and are accompanied by a change in forward and right angle light scatter. Fibrinogen prolongs the fMLF-induced response through 4 h. Changes in right angle light scatter parallel morphological change observed by light microscopy, indicating that flow cytometry can also be used to evaluate changes in cell morphology. Other chemoattractants were less effective at inducing a change in morphology — fMLF >> LTB4 = C5a > 1L-8 > PAF = LPS. Disruption of microtubules with colchicine altered forward light scatter and cell polarization while the disruption of microfilaments with cyto B abrogates all morphological alterations, demonstrating the involvement of the cytoskeleton in the chemotactic process of neutrophils.
- ItemCASPAR DAVID FRIEDRICH'S DEVELOPMENT THROUGH GERMAN ROMANTICISM(2014-05) Daly, Brandi; Hood College Arts and Humanities; HumanitiesCaspar David Friedrich was an important painter during the nineteenth century in Germany. He is classified as a German Romantic. The literary Romantics received his paintings enthusiastically, because they believed he visualized their concepts. Th.is Capstone examines German Romanticism, Friedrich, and Dresden Germany. An explanation of German Romanticism and how it developed is conducted in the first chapter. Friedrich's life, training, and artwork are surveyed .in the second chapter to explain how he was drawn to Romanticism. The third chapter inspects his influences in Dresden Germany, which was a Romantic center for landscape artists, writers and philosophers. These main points are discussed in order for the reader to comprehend how Friedrich developed his sublime and picturesque style.
- ItemInducible Morphological Defenses in Hooked Mussels, Ischadium recurvum: Response to Native and Non-native Crab Predators(2014-09) Cyrana, Michael V.; Hood College Biology; Biomedical and Environmental ScienceInducible morphological defenses can be an important factor in predator prey interactions. While Hooked mussels, Ischadium recurvum, have been shown to exhibit inducible defenses in response to predators within their range, the ability of Hooked mussels to mount a defense against non-native predators has not been explored. In order to investigate the ability of Hooked mussels to mount an inducible defense response to novel predators, Hooked mussels were exposed (for two months) to the constant effluent of the native Blue crab, Callinectes sapidus, the non-native Green crab, Carcinus maenus, and were compared to mussels that were not exposed to any crab effluent. Mussels exposed to Blue crab effluent produced significantly (p < 0.05) more byssal threads compared to both Green crab exposed and control mussels. Green crab exposed and control mussels showed no differences in byssal thread production (p > 0.05). The lack of an inducible response in Green-crab exposed mussels suggests that crab induced byssal thread production is specific to native crab predators as well as the fact that Hooked mussels are incapable of recognizing novel predators by their effluent alone.
- ItemThe Feeding Behavior of the Rusty Crayfish (Orconectes rusticus) in a Simulated Submerged Aquatic Grass Bed Environment(2010-05) Curtis, Matthew A.; Hood College Biology; Biomedical and EnvironmentalRusty crayfish (Orconectes rusticus) have been known to significantly alter, through consumption and removal, macrophytes or submerged aquatic vegetation (SAV) in streams and lakes they have invaded. The invasion of the 0. rusticus into the lower reaches of the Susquehanna River, combined with their ability to withstand low salinity stresses, creates the possibility they may eventually invade the northern Chesapeake Bay. The potential effects of 0. rusticus on such an estuarine system are unknown. Using microcosms simulating SAV composition of the Susquehanna Flats region of the Chesapeake Bay, I monitored for consumption and removal effects from an 0. rusticus invasion on three species of SAV (Vallisneria americana, Najas guadalupensis, and Myriophyllum spicatum). Microcosms were separated into three treatments: controls, crayfish only, and crayfish with an alternative food source. Three trials were conducted with each trial lasting five weeks. Data show that reduction of biomass to larger species of SAV such as V. americana and M. spicatum was limited, with the exception of the consumption or senescence of V americana flower and bud stems. However, biomass of the smaller sized species N. guadalupensis was almost completely removed. Further analysis looking at gut contents of 0. rusticus reinforced the hypothesis that they will consume Chesapeake Bay SAVs. My data also show that biomass reduction can be related to a seasonal component of crayfish feeding and behavior. Reductions in plant biomass could also be due to indirect effects from the crayfish including increased levels of total suspended solids leading to decreased ambient light levels.
- ItemA FIELD EXPERIMENT: THE EFFECT OF INTRODUCED LIGHT POLLUTION ON LIGHTENING BUGS (COLEOPTERA: LAMPYRIDAE) IN THE PIEDMONT REGION OF MARYLAND(2015-05) Costin, Kevin J.; Hood College Biology; Biomedical and Environmental ScienceCurrently, lampyridae species are believed to be in decline worldwide. Many reasons have been proposed to determine the cause of the decline, such as habitat destruction and pesticide use. The purpose of this study was to determine if light pollution could also be a cause of the decline. Light pollution is believed to be a cause of a decline in lampyridae populations because nocturnal males use the flash pattern and frequency to locate females of the same species. To test this hypothesis, I experimentally introduced a light source in grasslands adjacent to a forest edge. I then recorded the flash frequency before and after the light introduction and found a significant decline in the number of flashes per minute exhibited by lampyridae. Lampyridae play an important role in their ecosystems by controlling agricultural pests, so light pollution should be examined in attempts to reduce their decline.