A Simulation Study Using Terrestrial LiDAR Point Cloud Data to Quantify Spectral Variability of a Broad-Leaved Forest Canopy.

In this analysis, a method for construction of forest canopy three-dimensional (3D) models from terrestrial LiDAR was used for assessing the influence of structural changes on reflectance for an even-aged forest in Belgium. The necessary data were extracted by the developed method, as well as it was registered the adjacent point-clouds, and the canopy elements were classified. Based on a voxelized approach, leaf area index (LAI) and the vertical distribution of leaf area density (LAD) of the forest canopy were derived. Canopy⁻radiation interactions were simulated in a ray tracing environment, giving suitable illumination properties and optical attributes of the different canopy elements. Canopy structure was modified in terms of LAI and LAD for hyperspectral measurements. It was found that the effect of a 10% increase in LAI on NIR reflectance can be equal to change caused by translating 50% of leaf area from top to lower layers. As presented, changes in structure did affect vegetation indices associated with LAI and chlorophyll content. Overall, the work demonstrated the ability of terrestrial LiDAR for detailed canopy assessments and revealed the high complexity of the relationship between vertical LAD and reflectance.

Diversity of plasmids harboring blaCMY-2 in multidrug-resistant Escherichia coli isolated from poultry in Brazil.

Multidrug-resistance (MDR) has been increasingly reported in Gram-negative bacteria from the intestinal microbiota, environment and food-producing animals. Resistance plasmids able to harbor different transposable elements are capable to mobilize antimicrobial resistance genes and transfer to other bacterial hosts. Plasmids carrying blaCMY are frequently associated with MDR. The present study assessed the presence of plasmid-encoded ampC genes (blacmy, blamox, blafox, blalat, blaact, blamir, bladha, blamor) in commensal E. coli isolated from apparently healthy broiler chickens. Furthermore, we characterized the plasmids and identified those harboring the resistance genes. We isolated 144/200 (72%) of E. coli isolates with resistance to cefotaxime and the resistance gene identified was blaCMY-2. The pulsed-field gel electrophoresis (PFGE) analysis showed high diversity of the genetic profiles. The phylogenetic groups A, B1, B2, and D were identified among E. coli isolates and group D was the most prevalent. The PCR-based replicon typing (PBRT) analysis identified four distinct plasmid incompatibility groups (Inc) in MDR isolates. Moreover, plasmids harboring blaCMY-2, ranged in size from 50kb to 150kb and 51/144 (35%) belonged to IncK, 21/144 (14.5%) to IncB/O, 8/144 (5.5%) to IncA/C, 1/144 (0.5%) to IncI, while 63/144 (44.5%) were not typeable by PBRT. Overall, a high prevalence of blaCMY-2 genes was found in a diverse population of commensal MDR E. coli from poultry in Brazil, harbored into different plasmids.