RESUMEN
Literature covering diseases of the giant panda (Ailuropoda melanoleuca) is either in Chinese or focuses on infectious agents. Here we describe the clinical signs, gross and microscopic findings, and immunohistochemistry results of a B-cell lymphoma in multiple organs of a 35-y-old captive male giant panda. The animal was euthanized because of prolonged anorexia and vomiting. Postmortem examination revealed ascites, generalized lymphadenopathy, splenomegaly, hepatomegaly, and thickened gall bladder mucosa. Histologically, the architecture of these organs was effaced by a densely cellular neoplasm composed of large, CD79a-positive neoplastic B lymphocytes supported by a fine fibrovascular stroma. Neoplastic cells occasionally palisaded around an eosinophilic fibrillary center, sometimes resembling Homer Wright rosettes. To our knowledge, rosette-forming lymphoma has not been reported previously in animals.
RESUMEN
DNA replication, similar to other cellular processes, occurs within dynamic macromolecular structures. Any comprehensive understanding ultimately requires quantitative data to establish and test models of genome duplication. We used two different super-resolution light microscopy techniques to directly measure and compare the size and numbers of replication foci in mammalian cells. This analysis showed that replication foci vary in size from 210 nm down to 40 nm. Remarkably, spatially modulated illumination (SMI) and 3D-structured illumination microscopy (3D-SIM) both showed an average size of 125 nm that was conserved throughout S-phase and independent of the labeling method, suggesting a basic unit of genome duplication. Interestingly, the improved optical 3D resolution identified 3- to 5-fold more distinct replication foci than previously reported. These results show that optical nanoscopy techniques enable accurate measurements of cellular structures at a level previously achieved only by electron microscopy and highlight the possibility of high-throughput, multispectral 3D analyses.