SUMMARY
Background
Neural crest cells emerge by delamination from the dorsal neural tube and give rise to various components of the peripheral nervous system in vertebrate embryos. These cells change from non-motile into highly motile cells migrating to distant areas before further differentiation. Mechanisms controlling delamination and subsequent migration of neural crest cells are not fully understood. Slit2, a chemorepellant for axonal guidance that repels and stimulates motility of trunk neural crest cells away from the gut has recently been suggested to be a tumor suppressor molecule. The goal of this study was to further investigate the role of Slit2 in trunk neural crest cell migration by constitutive expression in neural crest cells.
Results
We found that Slit gain-of-function significantly impaired neural crest cell migration while Slit loss-of-function favored migration. In addition, we observed that the distribution of key cytoskeletal markers was disrupted in both gain and loss of function instances.
Conclusions
These findings suggest that Slit molecules might be involved in the processes that allow neural crest cells to begin migration and transitioning to a mesenchymal type.
We elaborate a cultural framing theory of legal cynicism -previously used to account for neighborhood variation in Chicago homicides -to explain Arab Sunni victimization and insurgent attacks during the U.S. post-invasion occupation of Iraq. Legal cynicism theory has an unrecognized power to explain collective and interpersonal violence in international as well as American settings. We expand on how "double and linked" roles of state and non-state actors can be used in this theory to analyze violence against Arab Sunni civilians. Arab Sunnis responded to their reports of unnecessary violent attacks by U.S./Coalition soldiers with a legally cynical framing of the U.S./Coalition-led invasion and occupation, the new Shia-dominated Iraq state, and its military and police. A post-invasion frame amplification of beliefs about state-based illegitimacy, unresponsiveness, and insecurity made it not only possible but predictable that Arab Sunni insurgent attacks would continue against U.S./Coalition forces and transfer to Shiadominated Iraq government forces. Violence in Iraq persisted despite Surge efforts to end the Arab Sunni insurgency.
The millions of survivors who fled from attacks to Sudanese-controlled displacement camps and the refugee camps in Chad are the living ghosts of the Darfur genocide. The 1948 Genocide Convention incorporates extermination by mass killing and elimination through forced migration as two distinct elements of genocide. Genocide scholars and public discourse emphasize extermination by killing, but they give far less explanatory attention to the elimination processes that the Genocide Convention describes as 'deliberately inflicting on the group conditions of life calculated to bring about its physical destruction'. (Article II United Nations 1948.) In Darfur, understanding the latter processes requires theoretical attention to the history of food, water, and famine and detailed methodological attention to temporal processes of displacement. We demonstrate how intentional state-led attacks on food and water massively dislodged Black Africans in Darfur from February 2003 to August 2004. The political leadership of the Sudanese state dehumanized and forcibly displaced Black Africans from their homes in Darfur to camps where they largely remain, not only through mass killings and rapes, but also by destroying life-sustaining access to food and water, leading to the genocidal elimination of group life in this region.
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