Trogocytosis by Entamoeba histolytica Mediates Acquisition and Display of Human Cell Membrane Proteins and Evasion of Lysis by Human Serum.

We previously showed that Entamoeba histolytica kills human cells through a mechanism that we termed trogocytosis ("trogo-" means "nibble"), due to its resemblance to trogocytosis in other organisms. In microbial eukaryotes like E. histolytica, trogocytosis is used to kill host cells. In multicellular eukaryotes, trogocytosis is used for cell killing and cell-cell communication in a variety of contexts. Thus, nibbling is an emerging theme in cell-cell interactions both within and between species. When trogocytosis occurs between mammalian immune cells, cell membrane proteins from the nibbled cell are acquired and displayed by the recipient cell. In this study, we tested the hypothesis that through trogocytosis, amoebae acquire and display human cell membrane proteins. We demonstrate that E. histolytica acquires and displays human cell membrane proteins through trogocytosis and that this leads to protection from lysis by human serum. Protection from human serum occurs only after amoebae have undergone trogocytosis of live cells but not phagocytosis of dead cells. Likewise, mutant amoebae defective in phagocytosis, but unaltered in their capacity to perform trogocytosis, are protected from human serum. Our studies are the first to reveal that amoebae can display human cell membrane proteins and suggest that the acquisition and display of membrane proteins is a general feature of trogocytosis. These studies have major implications for interactions between E. histolytica and the immune system and also reveal a novel strategy for immune evasion by a pathogen. Since other microbial eukaryotes use trogocytosis for cell killing, our findings may apply to the pathogenesis of other infections.IMPORTANCE Entamoeba histolytica causes amoebiasis, a potentially fatal diarrheal disease. Abscesses in organs such as the liver can occur when amoebae are able to breach the intestinal wall and travel through the bloodstream to other areas of the body. Therefore, understanding how E. histolytica evades immune detection is of great interest. Here, we demonstrate for the first time that E. histolytica acquires and displays human cell membrane proteins by taking "bites" of human cell material in a process named trogocytosis ("trogo-" means "nibble"), and that this allows amoebae to survive in human serum. Display of acquired proteins through trogocytosis has been previously characterized only in mammalian immune cells. Our study suggests that this is a more general feature of trogocytosis not restricted to immune cells and broadens our knowledge of eukaryotic biology. These findings also reveal a novel strategy for immune evasion by a pathogen and may apply to the pathogenesis of other infections

Assessment of stochastic and deterministic models of 6304 quasar lightcurves from SDSS Stripe 82

The optical light curves of many quasars show variations of tenths of a magnitude or more on time scales of months to years. This variation often cannot be described well by a simple deterministic model. We perform a Bayesian comparison of over 20 deterministic and stochastic models on 6304 QSO light curves in SDSS Stripe 82. We include the damped random walk (or Ornstein-Uhlenbeck [OU] process), a particular type of stochastic model which recent studies have focused on. Further models we consider are single and double sinusoids, multiple OU processes, higher order continuous autoregressive processes, and composite models. We find that only 29 out of 6304 QSO lightcurves are described significantly better by a deterministic model than a stochastic one. The OU process is an adequate description of the vast majority of cases (6023). Indeed, the OU process is the best single model for 3462 light curves, with the composite OU process/sinusoid model being the best in 1706 cases. The latter model is the dominant one for brighter/bluer QSOs. Furthermore, a non-negligible fraction of QSO lightcurves show evidence that not only the mean is stochastic but the variance is stochastic, too. Our results confirm earlier work that QSO light curves can be described with a stochastic model, but place this on a firmer footing, and further show that the OU process is preferred over several other stochastic and deterministic models. Of course, there may well exist yet better (deterministic or stochastic) models which have not been considered here.Comment: accepted by AA, 12 pages, 11 figures, 4 table

Infant Mortality and Financial Stability

Over four million newborn babies are encased in caskets and laid to rest in the world each year (Lawn 399). The comparison of infant mortality rates in the urban areas of Atlanta, Georgia and White Plains, New York shows the real cause of infant mortality: a lack of prenatal care due to inadequate financial income or assistance. With the establishment of free access to prenatal healthcare through organizations such as Children’s Healthcare of Atlanta, underprivileged mothers incapable of affording their prenatal expenses, can benefit along with their infants. This study represents a start in a move toward preserving the future generations through prenatal care

Absurdist Sci-Fi Humor: Comparable Attitudes Regarding Absurdism in Hitchhiker’s Guide to the Galaxy and Rick and Morty

Absurdism is a default thought of cosmic meaninglessness that society is continuously trying to solve to avoid depression and live with some ascribed meaning. Two parody science fiction series, Hitchikers’s Guide to the Galaxy and Rick and Morty, display similar outlooks on the answer to this social phenomenon. Both series explore the possible answers offered by religion, science, and philosophy as well as the inevitable failings of the three. Ultimately, both series agree that our pursuit of distractions, which hold personal and societal meaning, is the only answer because it is impossible to find meaning on a grander scale. The search is as meaningless as meaning itself, and the only solution is not to worry about it

Establishing Maritime Diplomacy in Southeast Asia: Balancing ASEAN Regional Interest in the Rise of Competing Great Power Rivalry

The resolution of the geopolitical status of China in the South China Sea becomes more urgent because the South China Sea issue is so closelylinked to the geopolitical security interests of China The longer the South China Sea issue is left unresolved the greater the geopolitical threat to China The presence and vicinity of foreign warships submarines and aircraft within the same dimensional space are potential hazards in the South China Sea can cause accidents and incidents A naval armaments program can create unwanted tension making maritime arms control and confidence-building as an important aspects of maritime diplomacy Someintriguing issues appear in this new environment such as how will Southeast Asia respond to great power rivalry inside and outside the region Will China s rise be accompanied with increasing fears of a great power s war or will ASEAN as the core regional grouping be an important catalyst in the interaction among nations Will the great powers tension be as dangerous as the Cold War or could it be worse as China is going to use its economic power as a strategic tool How will ASEAN collectively or as individual member countries in Southeast Asia respond to the great power rivalry of China US Japan India and Russia Will the arms race among states in the region endanger the balance of power in Southeast Asia region Will rivalry among great power countries in the East South China Sea destabilise the sea lanes of communication in the region which has sustained stability in the past several decade

Recent Developments in Employment Relations in the Philippines

We seek to describe recent developments in employment relations in the Philippines, placing these developments in the contexts of the distinctive elements of the Philippine social/political/industrial relations systems as well as the ongoing trade-based and functional integration of international markets and the recent regional economic crisis. We find that, while some firms are pursuing functional flexibility and more cooperative employment relations, the logic of competition has primarily induced firms to adopt practices that promote numerical flexibility such that a core-periphery workforce is created. We argue that the labor movement in the Philippines has been hampered in its efforts to effectively counter employer strategies by its low density, its fragmentation, and an unfavorable public policy environment; Philippine labor unions have, however, made some recent gains in organizing and inter-union coordination. We also argue that governments, both national and regional, have not done enough to counteract the negative effects of market integration on workers nor to evolve the Philippines into a higher value-added exporter