Dreadlocks (Dock) is necessary to regulate growth of the germline ring canals in the developing \u3ci\u3eDrosophila melanogaster\u3c/i\u3e egg chamber

Infertility is a prevalent issue in the United States, impacting 1.5 million women (1). A possible cause of infertility is defects in gametogenesis, or the formation of sperm and egg. Therefore, understanding the basic mechanisms that promote normal gamete formation could impact our understanding of infertility. The Drosophila melanogaster egg develops from an organ-like structure called an egg chamber. The egg chamber is composed of a central cluster of 16 germ cells that are connected to one another by intercellular bridges, called ring canals. These ring canals are composed of filamentous actin and allow the transfer of materials from supporting nurse cells to the developing oocyte. The ring canals form during early oogenesis and then expand 20-fold. Defects in ring canal formation or expansion can lead to infertility. The purpose of this project was to determine the role of the SH2/SH3 adaptor protein, Dreadlocks (Dock), in the germline ring canals of the developing Drosophila egg. Dock is involved in the formation of other actin-rich structures and has been shown to interact with other known ring canal proteins; thus, I examined whether depletion or mutation of Dock affected the process of nurse cell dumping or the size of the ring canals throughout development. Depletion of Dock by RNA interference (RNAi) caused an over-expansion of the outer diameter of the ring canals in egg chambers between the stages of 6 and 10b of oogenesis. Reducing Dock levels also enhanced the phenotype caused by depletion of two other ring canal components, the kinase Misshapen or the Arp2/3 complex. This led me to propose that Dock functions with Misshapen and the Arp2/3 complex to promote normal ring canal expansion and stability. Because of the conserved nature of these intercellular bridges and the proteins being studied, this work could provide significant insight into gametogenesis in higher organisms

Life without water

Anhydrobiosis, or life without water is commonly demonstrated by a number of plants and animals. These organisms have the capacity to loose all body water, remain dry for various periods, and then be revived by rehydration. While in the anhydrobiotic state, these organisms become highly resistant to several environmental stresses such as extremely low temperatures, elevated temperatures, ionizing radiation, and high vacuum. Since water is commonly thought to be essential for life, survival of anhydrobiotic organisms with an almost total loss of water is examined. A search of literature reveal that many anhydrobiotic organisms make large quantities of trehalose or other carbohydrates. Laboratory experiments have shown that trehalose is able to stabilize and preserve microsomes of sarcoplasmic reticulum and artificial liposomes. It was demonstrated that trehalose and other disaccharides can interact directly with phosopipid headgroups and maintain membranes in their native configuration by replacing water in the headgroup region. Recent studies show that trehalose is an effective stabilizer of proteins during drying and that it does so by direct interaction with groups on the protein. If life that is able to withstand environmental extremes has ever developed on Mars, it is expected that such life would have developed some protective compounds which can stabilize macromolecular structure in the absence of water and at cold temperatures. On Earth, that role appears to be filled by carbohydrates that can stabilize both membrane and protein stuctures during freezing and drying. By analog with terrestrial systems, such life forms might develop resistance either during some reproductive stage or at any time during adult existence. If the resistant form is a developmental stage, the life cycle of the organism must be completed with a reasonable time period relative to time when environmental conditions are favorable. This would suggest that simple organisms with a short life cycle might be most sucessful

Inflation, Inequality and Social Conflict

This paper presents a political economy model of inflation as a result of social conflict. Agents are heterogeneous in terms of income. Agents' income levels determine their ability to hedge against the effects of inflation. The interaction of heterogeneous cash holdings and preferences over fiscal policy leads to conflict over how to finance government expenditure. The model makes a number of predictions concerning which environments are conducive to the emergence of inflation. Inflation will tend to be higher in countries with higher inequality and with greater pro-rich bias in the political system. Conversely, the use of income tax will be higher in countries with lower inequality and less pro-rich bias. The model also predicts that although inequality and political bias will have an impact on the composition of revenue, it will have no effect on the overall level of government spending (assuming that spending is on public goods only). These results are largely confirmed by the empirical portion of the paper. The paper's novel features are its simplifications at the household level which allow for richer treatment of the income distribution and political process than in the related literature. The paper also gives unequivocal comparative statics results under relatively undemanding assumptions.probabilistic voting, distributional conflict, fiscal policy, inequality, inflation

Processing of satellite imagery at the National Environmental Satellite Service

The National Environmental Satellite Service (NESS) image product processing system is described. Other topics discussed include: (1) image processing of polar-orbiter satellite data; (2) image processing of geostationary satellite data; and (3) quality assurance and product monitoring