Pigmentation plasticity enhances crypsis in larval newts: Associated metabolic cost and background choice behaviour

In heterogeneous environments, the capacity for colour change can be a valuable adaptation enhancing crypsis against predators. Alternatively, organisms might achieve concealment by evolving preferences for backgrounds that match their visual traits, thus avoiding the costs of plasticity. Here we examined the degree of plasticity in pigmentation of newt larvae (Lissotriton boscai) in relation to predation risk. Furthermore, we tested for associated metabolic costs and pigmentation-dependent background choice behaviour. Newt larvae expressed substantial changes in pigmentation so that light, high-reflecting environment induced depigmentation whereas dark, low-reflecting environment induced pigmentation in just three days of exposure. Induced pigmentation was completely reversible upon switching microhabitats. Predator cues, however, did not enhance cryptic phenotypes, suggesting that environmental albedo induces changes in pigmentation improving concealment regardless of the perceived predation risk. Metabolic rate was higher in heavily pigmented individuals from dark environments, indicating a high energetic requirement of pigmentation that could impose a constraint to larval camouflage in dim habitats. Finally, we found partial evidence for larvae selecting backgrounds matching their induced phenotypes. However, in the presence of predator cues, larvae increased the time spent in light environments, which may reflect a escape response towards shallow waters rather than an attempt at increasing crypsisFinancial support was provided by the Spanish Ministry of Science and Innovation (MICINN), Grant CGL2012-40044 to IGM, and by the Universidad Autónoma de Madrid, Short Stay Grant to NPC. Additional financial support was provided by the MICINN, Grant CGL2015-68670-R to NP

Genome-Wide Analysis of Gene Expression in Primate Taste Buds Reveals Links to Diverse Processes

Efforts to unravel the mechanisms underlying taste sensation (gustation) have largely focused on rodents. Here we present the first comprehensive characterization of gene expression in primate taste buds. Our findings reveal unique new insights into the biology of taste buds. We generated a taste bud gene expression database using laser capture microdissection (LCM) procured fungiform (FG) and circumvallate (CV) taste buds from primates. We also used LCM to collect the top and bottom portions of CV taste buds. Affymetrix genome wide arrays were used to analyze gene expression in all samples. Known taste receptors are preferentially expressed in the top portion of taste buds. Genes associated with the cell cycle and stem cells are preferentially expressed in the bottom portion of taste buds, suggesting that precursor cells are located there. Several chemokines including CXCL14 and CXCL8 are among the highest expressed genes in taste buds, indicating that immune system related processes are active in taste buds. Several genes expressed specifically in endocrine glands including growth hormone releasing hormone and its receptor are also strongly expressed in taste buds, suggesting a link between metabolism and taste. Cell type-specific expression of transcription factors and signaling molecules involved in cell fate, including KIT, reveals the taste bud as an active site of cell regeneration, differentiation, and development. IKBKAP, a gene mutated in familial dysautonomia, a disease that results in loss of taste buds, is expressed in taste cells that communicate with afferent nerve fibers via synaptic transmission. This database highlights the power of LCM coupled with transcriptional profiling to dissect the molecular composition of normal tissues, represents the most comprehensive molecular analysis of primate taste buds to date, and provides a foundation for further studies in diverse aspects of taste biology

Costs and performance of irrigation projects: a comparison of Sub-Saharan Africa and other developing regions

High irrigation investment costs together with declining world prices for food and the failures of a number of high profile past irrigation projects are the main reasons for the reluctance of development agencies and governments in Sub-Saharan Africa to invest more resources in irrigation. This study aims to systematically establish whether costs of irrigation projects in Sub-Saharan Africa are truly high, determine the factors which influence costs and performance of irrigation projects, and recommend cost-reducing and performance-enhancing options to make irrigation investments in the region more attractive. It analyzes 314 irrigation projects implemented from 1967 to 2003 in 50 countries in Africa, Asia, and Latin America funded by the World Bank, African Development Bank and the International Fund for Agricultural Development

Lessons from irrigation investment experiences: cost-reducing and performance-enhancing options for Sub-Saharan Africa

This study aims to systematically establish whether costs of irrigation projects in SSA are truly high, determine the factors which influence costs and recommend cost-reducing options in order make irrigation investments in SSA more attractive. The study analyzes 314 irrigation projects implemented from 1967 to 2003 in 50 countries in Africa, Asia, and Latin America funded (or assisted) by the World Bank, African Development Bank and the International Fund for Agriculture Development. The sample includes "irrigation? projects, irrigation development with power generation ("irrigation with power?) projects, and irrigation component in multi-sectoral projects (MSPs). For the latter two types of project, only the cost of the irrigation component was included in the analyses. The study distinguishes projects according to purpose (ranging from purely new construction to purely rehabilitation), type of irrigation system (river diversion, reservoir-based, tank, river/groundwater-lift, and largely drainage or flood control), mode of O&M (government managed, jointly managed, farmer-managed), and major crops irrigated. All data are obtained from project completion (PCRs) and performance audit reports (PPARs) complemented with information from staff appraisal reports. Unit irrigation costs and project performance measured by economic internal rates of return are actual figures reported in PPARs or PCRs. This report examines whether the difference in unit costs in Sub-Saharan Africa compared with other regions is significant, and identifies the key determinants of unit investment costs and performance of irrigation projects. It makes three important contributions: (1) it confirms some earlier findings about irrigation projects; (2) it disproves some popularly-held notions and incorrect perceptions about unit costs and performance of irrigation projects in Sub-Saharan Africa; and (3) it provides empirical support to some existing irrigation investment policies and programs and a basis for reconsideration of others and introduction of new ones. The report presents recommendations for formulating better irrigation projects and a clear investment direction in agricultural water in Sub-Saharan Africa