A Three-Dimensional Technique for The Visualization of Mitochondrial Ultrastructural Changes in Pancreatic Cancer Cells.

Understanding the dynamic features of the cell organelle ultrastructure, which is not only rich in unknown information but also sophisticated from a three-dimensional (3D) perspective, is critical for mechanistic studies. Electron microscopy (EM) offers good imaging depth and allows for the reconstruction of high-resolution image stacks to investigate the ultrastructural morphology of cellular organelles even at the nanometer scale; therefore, 3D reconstruction is gaining importance due to its incomparable advantages. Scanning electron microscopy (SEM) provides a high-throughput image acquisition technology that allows for reconstructing large structures in 3D from the same region of interest in consecutive slices. Therefore, the application of SEM in large-scale 3D reconstruction to restore the true 3D ultrastructure of organelles is becoming increasingly common. In this protocol, we suggest a combination of serial ultrathin section and 3D reconstruction techniques to study mitochondrial cristae in pancreatic cancer cells. The details of how these techniques are performed are described in this protocol in a step-by-step manner, including the osmium-thiocarbohydrazide-osmium (OTO) method, the serial ultrathin section imaging, and the visualization display.

Emerging of two new subgenotypes of porcine reproductive and respiratory syndrome viruses in Southeast China.

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the leading swine pathogens and causes major economic loss to the global swine industry. In this study, a total of 49 PRRSV isolates were collected from different swine herds in seven provinces in Southeast China from 2014 to 2015. All the ORF5 genes and some Nsp2 genes were sequenced. Phylogenetic analysis showed that all the isolates belonged to the North America genotype. Among them, five isolates formed a new subgenotype IV derived from highly pathogenic PRRSV (HP-PRRSV). Six isolates formed subgenotype III, which were closely related to the NADC30 strain in the US. These isolates formed 13 putative N-linked glycosylation site (NGS) patterns based on N30, 33, 34, 35, 44 and 51. There were fewer NGSs of isolates in subgenotype IV than in subgenotype III. This indicates that the two new subgenotypes of PRRSV strains with different NGS patterns were spreading in those regions of China. The genetic diversity should be considered for the control and prevention of this disease.