Viral Metagenomics Analysis of Planktonic Viruses in East Lake,Wuhan,China

East Lake(Lake Donghu),located in Wuhan,China,is a typical city freshwater lake that has been experiencing eutrophic conditions and algal blooming during recent years.Marine and fresh water are considered to contain a large number of viruses.However,little is known about their genetic diversity because of the limited techniques for culturing viruses.In this study,we conducted a viral metagenomic analysis using a high-throughput sequencing technique with samples collected from East Lake in Spring,Summer,Autumn,and Winter.The libraries from four samples each generated 234,669,71,837,12,820,and 34,236 contigs(>90 bp each),respectively.The genetic structure of the viral community revealed a high genetic diversity covering 23 viral families,with the majority of contigs homologous to DNA viruses,including members of Myoviridae,Podoviridae,Siphoviridae,Phycodnaviridae,and Microviridae,which infect bacteria or algae,and members of Circoviridae,which infect invertebrates and vertebrates.The highest viral genetic diversity occurred in samples collected in August,then December and June,and the least diversity in March.Most contigs have low-sequence identities with known viruses.PCR detection targeting the conserved sequences of genes(g20,psbA,psbD,and DNApol)of cyanophages further confirmed that there are novel cyanophages in the East Lake.Our viral metagenomic data provide the first preliminary understanding of the virome in one freshwater lake in China and would be helpful for novel virus discovery and the control of algal blooming in the future.

Study of the Dynamics of Microcystis aeruginosa and its Cyanophage in East Lake using quantitative PCR

Dear Editor,East Lake,located in the middle and lower reaches of the Yangtze River,is a major source of drinking water for local residents.However,the large increase of population density and the rapid development of industry has resulted in heavy eutrophication of East Lake over the past few decades.Microcystis aeruginosa is a well-known

Stability analysis of proportional delayed projection neural network for quadratic programming problem

At present,projection neural network(PNN)with bounded time delay has been widely used for solving convex quadratic programming problem(QPP).However,there is little research concerning PNN with unbounded time delay.In this paper,we propose the proportional delayed PNN to solve QPP with equality constraints.By utilizing homeo morphism mapping principle,we prove the proportional delayed PNN exists with unique equilibrium point which is the optimal solution of QPP.Simultaneously,delay-dependent criteria about global exponential stability(GES)and global polynomial stability(GPS)are also acquired by applying the method of variation of constants and inequality techniques.On the other hand,when proportional delay factor q is equal to 1,the proportional delayed PNN becomes the one without time delay which still can be utilized for solving QPP.But in most situations,q is not equal to 1,and time delay is unpredictable and may be unbounded in the actual neural network,which causes instability of system.Therefore,it is necessary to consider proportional delayed PNN.A numerical example demonstrates that,compared with the proportional delayed Lagrange neural network,the proportional delayed PNN is faster in terms of convergence rate.The possible reason is that appropriate parameters make the model converge to the equilibrium point along the direction of gradient descent.