Carbon dynamics, net primary productivity (NPP) and human appropriated NPP (HANPP) across a forest‐cocoa farm landscape in West Africa

Terrestrial net primary productivity (NPP) is an important metric of ecosystem functioning; however, there is little empirical data on the NPP of human-modified ecosystems, particularly smallholder,perennial crops like cocoa (Theobroma cacao), which are extensive across the tropics. Human appropriated NPP (HANPP) is a measure of the proportion of a natural system’s NPP that has either been reduced through land-use change or harvested directly and, previously, has been calculated to estimate the scale of the human impact on the biosphere. Additionally, human-modification can create shifts in NPP allocation and decomposition, with concomitant impacts on the carbon cycle. This study presents the results of three years of intensive monitoring of forest and smallholder cocoa farms across disturbance, management intensity, distance from forest and farm age gradients. We measured among the highest reported NPP values in tropical forest, 17.57 ± 2.1 and 17.7 ± 1.6 Mg C ha-1 yr-1 for intact and logged forest respectively; however, the average NPP of cocoa farms was still higher, 18.8 ± 2.5 Mg C ha-1 yr-1, which we found was driven by cocoa pod production. We found a dramatic shift in litterfall residence times, where cocoa leaves decomposed more slowly than forest leaves and shade tree litterfall decomposed considerably faster, indicating significant changes in rates of nutrient cycling. The average HANPP value for all cocoa farms was 2.1 ± 1.1 Mg C ha-1 yr-1; however, depending on the density of shade trees it ranged from -4.6 to 5.2 Mg C ha-1 yr-1. Therefore, rather than being related to cocoa yield, HANPP was reduced by maintaining higher shade levels. Across our monitored farms 18.9% of farm NPP was harvested (i.e. whole cocoa pods) and only 1.1% (i.e.cocoa beans) was removed from the system; suggesting that the scale of HANPP in smallholder cocoa agroforestry systems is relatively small

Protected N-Acetyl Muramic Acid Probes Improve Bacterial Peptidoglycan Incorporation via Metabolic Labeling

Metabolic glycan probes have emerged as an excellent tool to investigate vital questions in biology. Recently, methodology to incorporate metabolic bacterial glycan probes into the cell wall of a variety of bacterial species has been developed. In order to improve this method, a scalable synthesis of the peptidoglycan precursors is developed here, allowing for access to essential peptidoglycan immunological fragments and cell wall building blocks. The question was asked if masking polar groups of the glycan probe would increase overall incorporation, a common strategy exploited in mammalian glycobiology. Here, we show, through cellular assays, that E. coli do not utilize peracetylated peptidoglycan substrates but do employ methyl esters. The 10-fold improvement of probe utilization indicates that (i) masking the carboxylic acid is favorable for transport and (ii) bacterial esterases are capable of removing the methyl ester for use in peptidoglycan biosynthesis. This investigation advances bacterial cell wall biology, offering a prescription on how to best deliver and utilize bacterial metabolic glycan probes.Fil: Brown, Ashley R.. University of Delaware; Estados UnidosFil: Wodzanowski, Kimberly A.. University of Delaware; Estados UnidosFil: Santiago, Cintia Cecilia. University of Delaware; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hyland, Stephen N.. University of Delaware; Estados UnidosFil: Follmar, Julianna L.. University of Delaware; Estados UnidosFil: Asare Okai, Papanii. University of Delaware; Estados UnidosFil: Grimes, Catherine Leimkuhler. University of Delaware; Estados Unido