A metagenomic insight into the Yangtze finless porpoise virome.

The Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) inhabiting the Yantze River, China is critically endangered because of the influences of infectious disease, human activity, and water contamination. Viral diseases are one of the crucial factors that threatening the health of Yangtze finless porpoise. However, there are few studies which elaborate the viral diversity of Yangtze finless. Therefore, this study was performed to investigate the viral diversity of Yangtze finless by metagenomics. Results indicated that a total of 12,686,252 high-quality valid sequences were acquired and 2,172 virus reads were recognized. Additionally, we also obtained a total of 10,600 contigs. Phages was the most abundant virus in the samples and the ratio of DNA and RNA viruses were 69.75 and 30.25%, respectively. Arenaviridae, Ackermannviridae and Siphoviridae were the three most predominant families in all the samples. Moreover, the majority of viral genus were Mammarenavirus, Limestonevirus and Lambdavirus. The results of gene prediction indicated that these viruses play vital roles in biological process, cellular component, molecular function, and disease. To the best of our knowledge, this is the first report on the viral diversity of Yangtze finless porpoise, which filled the gaps in its viral information. Meanwhile, this study can also provide a theoretical basis for the establishment of the prevention and protection system for virus disease of Yangtze finless porpoise.

Optimized criteria for angular parameter selection for the Chin-Shifrin integral transform inversion.

The accuracy of the particle size distribution (PSD) recovered from laser diffraction measurements by the Chin-Shifrin integral transform algorithm is reduced unless the proper angular parameters, including the lower and upper angular integration limits (θmax and θmin) and the angular resolution (Δθ), are used. To determine the selection criteria for these parameters, we use two metrics: the inversion error of the non-negative PSD, ε1, and the fitting error of the scattered laser light, ε2. By studying the variation of the minimum θmax and ε2 with the particle size at different inversion errors, and by analyzing the inversion error, as θmin and Δθ are varied, the optimized selection criteria for the minimum θmax, θmin and Δθ are obtained respectively. The inversion errors of the Chin-Shifrin algorithm with different selection criteria are compared, the different PSDs are recovered, and the optimal pixel selection range of the linear charge-coupled-device (CCD) array is determined according to the optimized selection criteria. Simulation results show that the optimized selection criteria for the angular parameters make the PSDs retrieved with the Chin-Shifrin algorithm more accurate.