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Scientists can now visualize developmental gene expression quantitatively in three dimensions and at single-cell resolution. Recent advances in optical microscopy and fluorescent genetic tags allow imaging of gene expression in live animals, as well. Eventually, researchers hope to construct virtual atlases of animal development.
Dedifferentiation is an important biological phenomenon whereby cells regress from a specialized function to a simpler state reminiscent of stem cells. Stem cells are self-renewing cells capable of giving rise to differentiated cells when supplied with the appropriate factors. Stem cells that are derived by dedifferentiation of one's own cells could be a new resource for regenerative medicine, one that poses no risk of genetic incompatibility or immune rejection and provokes fewer ethical debates than the use of stem cells derived from embryonic tissue. Until now, it has not been quite clear why some differentiated cell types can dedifferentiate and proliferate, whereas others cannot. A better understanding of the mechanisms involved in dedifferentiation may enable scientists to control and possibly alter the plasticity of the differentiated state, which may lead to benefits not only in stem cell research but also in regenerative medicine and even tumor biology. If so, dedifferentiation will offer an ethically acceptable alternative route to obtain an abundant source of stem cells. Dedifferentiation is likely to become a new focus of stem cell research. Here we compile recent advances in this emerging but significant research, highlighting its central concepts, research findings, possible signaling pathways, and potential applications.
Globalization is often associated with deforestation, but its impacts on forest recovery are less known. We analyzed socioeconomic data, land-use surveys, and satellite imagery to monitor changes in woody cover in El Salvador from the early 1990s to the present. Even where rural population density exceeded 250 people per square kilometer, we documented a 22% increase in the area with more than 30% tree cover, and a 7% increase in the area with more than 60% tree cover. Woodland resurgence reflected processes including civil war, retraction of the agricultural frontier, and international migration and associated remittances. Agrarian reform, structural adjustment, and emerging environmental ideas also played a role in woodland dynamics. Remittances may be especially important for woodland recovery in El Salvador, enabling people in rural areas to buy food without all of them needing to grow and sell it. This study adds to our understanding of the complexity of land-use change in emerging globalized economies and of potential conservation approaches for inhabited landscapes.
In scientific investigations, performing initial exploratory studies can help in generating hypotheses and deciding what to study in more detail later. Little-known modern graphical methods can be powerful tools for exploration of complex data. We illustrate several such types of graphs and discuss what we have learned from them. The data come from a study designed to quantify physical and enzymatic changes in both sides of chicken brains after developmental exposure to dioxin, with half the eggs treated with red light. The data corresponded to 160 combinations of dose, light presence or absence, brain side, and brain dimension or biochemical activity, making the graphical methods especially helpful for assessing the presence and extent of asymmetry in the responses. We provide graphical examples using a pairs plot and several trellis plots in which the data appeared consistent or inconsistent with prior expectations and suggested unexpected findings that will motivate new research.
The critical role of private lands in the conservation of threatened and endangered species has been well documented. Although researchers and policymakers recognize the need to include private lands in conservation planning, they often falter over the question of how to do so. The current literature contains only a few research studies on species of conservation concern on private lands. We describe our experiences with the partnership-based approach we used with private landowners to conduct research on the mountain plover (Charadrius montanus), a species that was proposed for listing under the US Endangered Species Act. In our approach, research is an objective tool that is accessible to all partners involved, and researchers do not take a lead role in the resolution of sociopolitical issues. We provide guidelines for conducting studies on private land, with the goal of improving researchers' interactions with private landowners.
Explosive growth in Las Vegas, Nevada, has stimulated demand for additional water supplies. To meet these needs, local officials hope to obtain rights to about 200,000 acre-feet (246.70 million cubic meters [m3]) per year from a regional groundwater aquifer extending from Salt Lake City, Utah, to Death Valley, California. Officials from satellite communities are pursuing rights to an additional 870,487 acre-feet (1.07 billion m3) per year. If granted, these new permits would trigger declines in groundwater across at least 78 basins covering nearly 130,000 square kilometers. Water-rights decisions have historically interpreted economic development as a more compelling public interest than maintenance of natural systems. If economic development continues to drive allocation decisions, consequent declines in the water table, spring discharge, wetland area, and streamflow will adversely affect 20 federally listed species, 137 other water-dependent endemic species, and thousands of rural domestic and agricultural water users in the region. Reducing consumption and implementing cost-effective technologies, such as recovery of urban runoff and shallow saline groundwater, indirect reuse of potable water, and desalinization, offer ways to meet metropolitan and ecological needs within the limits of the resource.
The applied ecological discipline of classical biological control (CBC) has a long history, bolstered by some spectacular successes in the management of pest insect and plant species. A major poster child of CBC is the control of prickly pear (Opuntia spp.) in Australia by the moth Cactoblastis cactorum. In this article we investigate the idiosyncrasies of this CBC program and relate it to contemporary CBC, highlighting the intensive rearing and spatially extensive distribution effort critical to the rapid success of this project. We also emphasize the importance of the sociopolitical and economic context of the Opuntia CBC program and its role in its success. We use these historical clarifications to temper the expectations of equivalent successes in future CBC projects. Cactoblastis cactorum has recently invaded North America, and its threat to native cacti is of concern. We examine the global use of this moth as a biocontrol agent to clarify the nature of the hazard that it may pose as an invader in North and Central America.