A Cross-Species Analysis of MicroRNAs in the Developing Avian Face

Higher vertebrates use similar genetic tools to derive very different facial features. This diversity is believed to occur through temporal, spatial and species-specific changes in gene expression within cranial neural crest (NC) cells. These contribute to the facial skeleton and contain species-specific information that drives morphological variation. A few signaling molecules and transcription factors are known to play important roles in these processes, but little is known regarding the role of micro-RNAs (miRNAs). We have identified and compared all miRNAs expressed in cranial NC cells from three avian species (chicken, duck, and quail) before and after species-specific facial distinctions occur. We identified 170 differentially expressed miRNAs. These include thirty-five novel chicken orthologs of previously described miRNAs, and six avian-specific miRNAs. Five of these avian-specific miRNAs are conserved over 120 million years of avian evolution, from ratites to galliforms, and their predicted target mRNAs include many components of Wnt signaling. Previous work indicates that mRNA gene expression in NC cells is relatively static during stages when the beak acquires species-specific morphologies. However, miRNA expression is remarkably dynamic within this timeframe, suggesting that the timing of specific developmental transitions is altered in birds with different beak shapes. We evaluated one miRNA:mRNA target pair and found that the cell cycle regulator p27KIP1 is a likely target of miR-222 in frontonasal NC cells, and that the timing of this interaction correlates with the onset of phenotypic variation. Our comparative genomic approach is the first comprehensive analysis of miRNAs in the developing facial primordial, and in species-specific facial development

Supporting food security in the 21st century through resource-conserving increases in agricultural production

<p>Abstract</p> <p>The Green Revolution was accomplished under a set of demographic, economic, climatic and other conditions in the 20th century that have been changing and will surely be different and more difficult in the decades ahead. The suitability and sustainability of any given agricultural technology depends on factors like resource availability and productivity, energy costs, and environmental constraints. The achievements of Green Revolution technologies in the 1960s and 1970s came at a critical time of impending food shortages, and the world’s people would be worse off without them. However, the rate of yield improvement for cereal production has been slowing since the mid-1980s.</p> <p>Looking ahead at the foreseeable circumstances under which 21st century agricultural producers must try to assure food security, there will be need for technologies that are less dependent on resources that are becoming relatively scarcer, like arable land and water, or becoming relatively more costly, like energy and petrochemical-based inputs. This paper considers agroecologically-based innovations that reduce farmers’ dependence on external inputs, relying more on endogenous processes and existing potentials in plants and soil systems. Such resource-conserving production represents a different approach to meeting food security goals.</p> <p>While these innovations are not yet fully understood and are still being researched, there are good agronomic reasons to account for their effectiveness, and scientific validations are accumulating. Enough successes have been recorded from making changes in the management of plants, soil, water and nutrients that more attention from researchers, policy-makers and practitioners is warranted, especially given the need to adapt to, and to mitigate the effects of, climate change. The same agroecological concepts and management methods that are enhancing factor productivity in rice production are giving similar results with other crops such as wheat, finger millet, sugarcane, mustard, and tef.</p> <p>Genetic potentials are the starting point for any and all agricultural production, and current efforts to improve food security and nutrition through plant breeding efforts should continue. However, future research and production strategies could beneficially seek to capitalize on biological processes and potentials existing within crops and in their supporting soil systems, rather than focusing so predominantly on making modifications in genetic factors. Scientific advances in the domains of microbiology, soil ecology and epigenetics could foreseeably assist farmers in meeting production and income goals with resource-economizing methods. It remains to be seen to what extent agroecologically-informed methods can help farmers meet expected agricultural production requirements to ensure global food security, but this direction deserves more attention and support.</p