Diffusionless Transition in Tricosane and Reversible Inhibition of Calcium Oxalate Monohydrate: Two Studies of Crystal Growth

The process of crystal growth has been intensively studied, for both its academic interest and industrial importance. I report here two studies of crystal growth. The normal alkanes are an interesting, both in terms of their intrinsic properties and because many biological materials contain hydrocarbon domains. The normal alkanes often exhibit complicated phase behaviour, with phase diagrams containing multiple solid phases. We report here a curious pattern of twinned domains seen in one phase of tricosane (C23H48), which we have studied by X-ray diffraction, as well as by optical and atomic force microscopy. This pattern is seen in the rotator RV phase, a monoclinic arrangement of tricosane molecules without orientational order. Transitions between this polymorph and the orthorhombic phase lying at higher temperatures preserve features at the molecular level, and thus represent a diffusionless, martensitic-like transformation. Calcium oxalate monohydrate (COM) is the primary constituent of most kidney stones. Certain proteins, such as osteopontin (OPN), inhibit stone formation. The inhibition of crystallization due to adsorbed impurities is usually explained in terms of a model proposed in 1958 by Cabrera and Vermilyea, which hypothesizes that impurities adsorb to growth faces and pin growth steps, thus impeding their progress via the Gibbs-Thomson effect. To determine the role of OPN in the biomineralization of kidney stones, crystal growth on the {010} face of COM was examined in real time by atomic force microscopy in the presence of a synthetic peptide. We observed clear changes in the morphology of the growth-step structure and a decrease in step velocity upon addition of inhibitors, suggesting adsorption on the {010} growth hillocks. Experiments in which inhibitors were replaced in the growth cell by a supersaturated solution showed that COM hillocks are able to fully recover to their pre-inhibited state. Our results suggest that recovery occurs through incorporation of the peptide into the growing crystal, rather than by, e.g., desorption from the growth face. This work provides new insights into the mechanism by which crystal growth is inhibited, with important implications for the design of therapeutic agents for kidney stone disease and other forms of pathological calcification

Foraging Behavior of Tetramorium Caespitum in an Urban Environment: the Effect of Food Quality on Foraging

Animals\u27 foraging strategies are directly related to their fitness. Proposed models of optimal foraging assume that animals strategize in terms of maximizing benefits over the cost of acquiring resources. Ants are social insects that are comparable in biomass to humans inhabiting the plant. As such, it is crucial to understand the foraging strategies of such an influential member of the ecosystem. With the ever-increasing rate of urbanization and human encroachment, it is even more important to consider the foraging patterns of species inhabiting urban areas. In this study we investigate optimal foraging strategies in the pavement ant, Tetramorium caespitum. Specifically, our study examined if pavement ant colonies would alter their foraging behavior so as to maximize benefits and minimize costs. To do this, we exposed the ants to food of two varying nutritional qualities to test how they allocated foragers across these two resources.Food quantity, distance to the food source and terrain were the same in both types of resources. Across a two day period, we saw that T. caespitum colonies increased ant recruitment when food quality increased and decreased ant recruitment when food quality decreased. Our control treatments where food quality did not change also did not see a change in ant recruitment. This study shows that species that live in urban areas, such as T. caespitum, can adapt to forage optimally. Studies like this can be used to make predictions about survival of species that are newly associated with urban environments

Isolation & Characterization of Bacteria in the Built Environment: Measuring The Effect of Pharmaceuticals on Growth

This work reports the isolation and characterization of bacteria from the built environment at Gettysburg College in Gettysburg, PA. Surfaces of a water fountain on campus were swabbed and serially streaked to isolate multiple bacteria on R2A agar. Following multiple rounds of growth, the unknown microbial candidates were narrowed to two visibly­distinct organisms. Morphological characterization and phylogenetic identification based on 16S rDNA sequencing revealed that the isolates were Chryseobactierum hispalense and Microbacterium maritypicum. We report synergistic biofilm formation between Chryseobactierum hispalense and Microbacterium maritypicum. The contamination of drinking water with varying levels of personal care products and pharmaceuticals (PCPPs) is well documented. Additionally, these environmental pollutants and their derivatives affect aquatic life, as illustrated with effect of the antidepressant fluoxetine on mudsnails. To determine if previously reported contaminants affect freshwater bacteria, we assessed both planktonic growth and biofilm formation following exposure to nalidixic acid (non­fluorinated quinolone antibiotic), diphenhydramine (over­the­counter drug Benadryl), and fluoxetine (Prozac)

Etudes phytochimique et pharmacologique de Bridelia ferruginea benth (euphorbiaceae) sur la motricite du Taenia coli de cobaye

L’étude phytochimique des extraits de Bridelia ferruginea a montré que cette plante contient des quinones, des tanins catéchiques et galliques, des alcaloïdes, des stérols, des polyterpènes, des polyphénols, des composés réducteurs, des flavonoïdes et des saponosides. L’extrait aqueux de Bridelia ferruginea provoque entre 10-5mg/mL et 10-1mg/mL une augmentation des contractions rythmiques de muscle lisse Taenia coli de cobaye. Ces effets inotropes positifs antagonisés par l’Atropine (10-6mg/mL) sont totalement abolis en milieu pauvre (0Ca2+) et dépourvus de calcium (0Ca2++ EDTA 10-5M).Ces résultats suggèrent la présence de substances cholinomimétiques dans l’extrait brut. Ces substances favoriseraient l’entrée de calcium dans la cellule musculaire lisse par stimulation des récepteurs muscariniques. Ces substances cholinomimétiques justifieraient l’usage traditionnel de cette plante comme laxatif ou purgatif.Mots-clés : Bridelia ferruginea, Taenia coli, récepteur muscarinique.

Composition chimique d’un extrait aqueux de bridelia ferruginea benth. (euphorbiaceae) et études de ses effets toxicologique et pharmacologique chez les mammifères.

La caractérisation des constituants chimiques de l’extrait aqueux de Bridelia ferruginea (SEA) a révélé la présence de quinones, de tanins catéchiques et galliques, d’alcaloïdes, de stérols, de polyterpènes, de polyphénols, de composés réducteurs, de flavonoïdes et de saponosides.L’étude de la toxicité aiguë de SEA, réalisée sur des souris, a montré que l’extrait aqueux de Bridelia ferruginea administré par voie orale est modérément toxique (DL50 égale à 3568,88 ± 308,45 mg/kg PC). En revanche, la même substance est très toxique (DL50 égale à 111,38 ± 29,3 mg/kg PC) lorsqu’elle est administrée par voie intrapéritonéale. Pour des doses comprises entre 5.10-3 g/kg de PC et 4.10-2 g/kg de PC, SEA provoque une hypotension dose-dépendante chez le lapin. Cette hypotension étant inhibée par l’atropine, l’extrait aqueux de Bridelia ferruginea contiendrait probablement des substances cholinomimétiques de type muscarinique.Mots-clés : Bridelia ferruginea, toxicologie, phytochimie, pharmacologie

Extraction of Heterodera cajani cysts using modified sieving technique

A soil suspension was sieved through 60, 80 and 100 mesh sieves to remove H. cajani cysts. Approximately 10-22% of the cysts passed through the 60 mesh but were recovered on the 80 mesh. It is therefore suggested that this mesh should be used instead of a 60 mesh for estimating the cyst number of H. cajani

Effects of Soil Solarization on Nematodes Parasitic to Chickpea and Pigeonpea

Solarization by covering the soil with transparent polyethylene sheets during the summer months (April, May, June) in 1984 and 1985 significantly (P = 0.01) reduced the population densities of nematodes (Heterodera cajani, Rotylenchulus reniformis, Helicotylenchus retusus, Pratylenchus sp., and Tylenchorhynchus sp.) parasitic to chickpea and pigeonpea. Population density reductions of 93% of Heterodera cajani eggs and juveniles, 99% ofHelicotylenchus retusus, 98% ofPratylenchus sp., and 100% ofR. reniformis were achieved by solarization in 1984. Irrigation before covering soil with polyethylene improved (P = 0.01) the effects of solarization in reducing the population densities of Heterodera cajani. Similar trends in population density reductions were observed in 1985, but the solarization effects were not the same. Nematode population reductions in the 1984-85 season were evident until near crop harvest, but in the 1985-86 season the effects on nematode populations were not as great and did not last until harvest. Factors such as rains during the solarization, duration of solarization, and sunshine hours may have influenced the efficacy of solarization. Solarization for two seasons reduced the population densities each year about the same as single season solarization, and residual effects of solarization on nematode populations did not last for more than a crop season