Imaging features of disseminated xanthogranulomatous inflammation in eclectus parrots (Eclectus roratus)

Xanthogranulomatous disease is a rare condition, which can be caused by infection, inflammation, hemorrhage, immunologic disease, or inherited lysosomal disorders. It is characterized by non‐intracellular lipid and cholesterol deposits among an inflammatory infiltrate of vacuolated macrophages and giant cells. The diagnosis of xanthogranulomatous disease is challenging, with nonspecific imaging findings often misinterpreted as aggressive neoplastic processes in humans. In this retrospective case series study, we describe the diagnostic imaging characteristics of a disseminated xanthogranulomatous condition identified in five eclectus parrots (Eclectus roratus). Decreased serosal detail and celomic distension were present in all three birds radiographed, with multifocal variably sized celomic mineralization (3/3 birds), and extracelomic mineralized masses (1/3 birds). Celomic effusion with foci of celomic mineralization and hepatomegaly were identified in all birds (3/3) imaged with ultrasound. Finally, a mineralized mural ventricular mass was present in one of three patients imaged with CT, multifocal celomic mineralization with moderate to severe celomic effusion in two of three patients, diffuse severe proventricular and intestinal dilation in all three patients, and atherosclerosis of the major arterial trunks in all three patients. Veterinary radiologists should be aware of this inflammatory condition in birds, especially in eclectus parrots, and should be able to recognize the imaging features of xanthogranulomatous inflammation.     

Comparison of chloroform fumigation-extraction, phospholipid fatty acid, and DNA methods to determine microbial biomass in forest humus

Techniques developed to measure microbial biomass in mineral soils may not give reliable results in humus. We evaluated the relationships between three techniques to estimate microbial biomass in forest humus: chloroform fumigation-extraction (CFE), total extractable phospholipid fatty acids (PLFA), and extractable DNA. There was a good relationship between PLFA and CFE (R²=0.96), with a slope slightly different from that previously reported for mineral soils (1 nmol PLFA corresponded to a flush of 3.2 μg C released by fumigation in humus cf. 2.4 μg C in mineral soil). There was no relationship between DNA concentration and the other two measurements of microbial biomass. This may be due, in part, to the high fungal biomass in forest humus, as DNA concentration per unit biomass is much more variable for fungi than bacteria.     

Microbial communities in forest floors under four tree species in coastal British Columbia

We compare forest floor microbial communities in pure plots of four tree species (Thuja plicata, Tsuga heterophylla, Pseudotsuga menziesii, and Picea sitchensis) replicated at three sites on Vancouver Island. Microbial communities were characterised through community level physiological profiles (CLPP), and profiling of phospholipid fatty acids (PLFA).Microbial communities from cedar forest floors had higher potential C utilisation than the other species. The F layer of the forest floor under cedar contained significantly higher bacterial biomass (PLFA) than the F layer under the other three tree species. There were differences in microbial communities among the three sites: Upper Klanawa had the highest bacterial biomass and potential C utilisation; this site also had the highest N availability in the forest floors. Forest floor H layers under hemlock and Douglas-fir contained greater biomass of Gram positive, Gram negative bacteria and actinomycetes than F layers based on PLFA, and H layers under spruce contained greater biomass of Gram negative bacteria than F layers. There were no significant differences in bacterial biomass between forest floor layers under cedar. Fungal biomass displayed opposite trends to bacteria and actinomycetes, being lowest in cedar forest floors, and highest in the F layer and at the site with lowest N availability. There were also differences in community composition among species and sites, with cedar forest floors having a much lower fungal:bacterial ratio than spruce, hemlock and Douglas-fir. The least fertile Sarita Lake site had a much greater fungal:bacterial ratio than the more fertile San Juan and Upper Klanawa sites. Forest floor layer had the greatest effect on microbial community structure and potential function, followed by site, and tree species. The similarity in trends among measures of N availability and microbial communities is further evidence that these techniques provide information on microbial communities that is relevant to N cycling processes in the forest floor.