Neural Crest Cell Survival Is Dependent on Rho Kinase and Is Required for Development of the Mid Face in Mouse Embryos

Neural crest cells (NCC) give rise to much of the tissue that forms the vertebrate head and face, including cartilage and bone, cranial ganglia and teeth. In this study we show that conditional expression of a dominant-negative (DN) form of Rho kinase (Rock) in mouse NCC results in severe hypoplasia of the frontonasal processes and first pharyngeal arch, ultimately resulting in reduction of the maxilla and nasal bones and severe craniofacial clefting affecting the nose, palate and lip. These defects resemble frontonasal dysplasia in humans. Disruption of the actin cytoskeleton, which leads to abnormalities in cell-matrix attachment, is seen in the RockDN;Wnt1-cre mutant embryos. This leads to elevated cell death, resulting in NCC deficiency and hypoplastic NCC-derived craniofacial structures. Rock is thus essential for survival of NCC that form the craniofacial region. We propose that reduced NCC numbers in the frontonasal processes and first pharyngeal arch, resulting from exacerbated cell death, may be the common mechanism underlying frontonasal dysplasia

Chapter 9. Precision Agriculture and Food Security in Africa

Background and Significance of the topic: The chapter gives an overview of precision agriculture and its impacts on food security in Africa. Methodology: Methods and concepts of precision agriculture are described including crop, soil and position sensors; which include global positioning and remote sensing applications in detection of crop stress, monitoring variability, soils, weeds, and diseases. Machine controls and computer based systems are also briefly described. Application/Relevance to systems analysis: There are a number of operations that can benefit from precision agriculture at field level, including soil preparation, fertilisation, irrigation and weed management. In Africa, the benefits of precision agriculture include improved food security through increases in water and nutrient use efficiency, and timely management of activities such as weed control. Precision agriculture has saved costs of inputs in both commercial and smallholder farming in Africa. Pollution control of ground and surface water sources has slowed down where fertiliser and agrochemical applications are now more efficient. Policy and/or practice implications: Two examples of precision agriculture application in Africa are presented; FruitLook which is used by farmers in the Western Cape in South Africa as a state-of the art information technology that helps deciduous fruit and grape farmers to be water efficient and climate-smart. The Chameleon and Wetting Front Detector Sensors have enabled small scale farmers in Mozambique, Tanzania, and Zimbabwe to cut down irrigation frequency fifty times and double productivity. Discussion and conclusion: It is clear that precision agriculture has played a major role in improving food security in Africa through the efficient use of inputs such as fertiliser and water, while also reducing environmental pollution and degradation