The proper phase difference of traffic signals for adjacent intersections could decrease the time of operational delay. Some theorems show how to minimize the total average delay time for vehicle operating at adjacent...The proper phase difference of traffic signals for adjacent intersections could decrease the time of operational delay. Some theorems show how to minimize the total average delay time for vehicle operating at adjacent intersections under given conditions. If the distance and signal cycles of adjacent intersections satisfy with specific conditions, the total average delay time would achieve zero. If the signal cycles of adjacent intersections and the phase difference of them are co-prime numbers, the total average delay time would be a constant. In general, if signal cycles of adjacent intersections and the phase difference of them are reducible numbers, the minimum total average delay time would be solved by the given algorithm. Numerical experiments have verified the rationality of these theorems.展开更多
Sorbus pohuashanensis(Hance) Hedl. is a potential horticulture and medicinal plant, but its genomic and genetic backgrounds remain unknown. Here, we sequence and assemble the S. pohuashanensis reference genome using P...Sorbus pohuashanensis(Hance) Hedl. is a potential horticulture and medicinal plant, but its genomic and genetic backgrounds remain unknown. Here, we sequence and assemble the S. pohuashanensis reference genome using Pac Bio long reads. Based on the new reference genome, we resequence a core collection of22 Sorbus spp. samples, which are divided into 2 groups(G1 and G2) based on phylogenetic and PCA analyses. These phylogenetic clusters are highly consistent with their classification based on leaf shape.Natural hybridization between the G1 and G2 groups is evidenced by a sample(R21) with a highly heterozygous genotype. Nucleotide diversity(π) analysis shows that G1 has a higher diversity than G2 and that G2 originated from G1. During the evolution process, the gene families involved in photosynthesis pathways expanded and the gene families involved in energy consumption contracted. RNA-seq data suggests that flavonoid biosynthesis and heat-shock protein(HSP)-heat-shock factor(HSF) pathways play important roles in protection against sunburn. This study provides new insights into the evolution of Sorbus spp.genomes. In addition, the genomic resources, and the identified genetic variations, especially those related to stress resistance, will help future efforts to produce and breed Sorbus spp.展开更多
Biopolymer chitin and its derivatives have a wide range of applications in different fields.Chitin is primarily produced from marine crustacean by strong acid and strong alkali treatment.To reduce the environmental ha...Biopolymer chitin and its derivatives have a wide range of applications in different fields.Chitin is primarily produced from marine crustacean by strong acid and strong alkali treatment.To reduce the environmental hazardous in the production of chitin,post-fermentation fungal biomass waste like fungi cell walls provides a viable alternative source for chitin.In this study,improved chitin content in yeast cell wall was achieved by overexpressing chitin biosyntheic pathway related genes.The chitin content was 51.5μg/mg cell wall and 122.9μg/mg cell wall in strain GS-1.10(gfat,uap and chs1 genes overexpression)and strain GS-2.6(gfat,gna1,agm1,uap and chs1 genes overexpression),which were 44.3%and 244.4%higher than that in control strain GS115,respectively.By overexpressing another chitin synthase gene(chs3),the chitin content in strain GS-3.10 was further increased to 136.2μg/mg cell wall,which was 10.8%and 281.6%higher than that in GS-2.6 and in control GS115,respectively.Moreover,chitin yield was further improved by various culture conditions optimization,and reached 162.4μg/mg cell wall,which was 4.43 times of that in the starting strain GS115.The final titer of chitin was 2.23 g/L culture broth in 84 h fed-batch fermentation in a 5 L bioreactor.To our knowledge,this is the first report of chitin production in engineered Pichia pastoris via biosynthetic pathway enhancement.展开更多
文摘The proper phase difference of traffic signals for adjacent intersections could decrease the time of operational delay. Some theorems show how to minimize the total average delay time for vehicle operating at adjacent intersections under given conditions. If the distance and signal cycles of adjacent intersections satisfy with specific conditions, the total average delay time would achieve zero. If the signal cycles of adjacent intersections and the phase difference of them are co-prime numbers, the total average delay time would be a constant. In general, if signal cycles of adjacent intersections and the phase difference of them are reducible numbers, the minimum total average delay time would be solved by the given algorithm. Numerical experiments have verified the rationality of these theorems.
基金supported by the Fund of the National Natural Science Foundation of China (grant number 31770369) to J. Z。
文摘Sorbus pohuashanensis(Hance) Hedl. is a potential horticulture and medicinal plant, but its genomic and genetic backgrounds remain unknown. Here, we sequence and assemble the S. pohuashanensis reference genome using Pac Bio long reads. Based on the new reference genome, we resequence a core collection of22 Sorbus spp. samples, which are divided into 2 groups(G1 and G2) based on phylogenetic and PCA analyses. These phylogenetic clusters are highly consistent with their classification based on leaf shape.Natural hybridization between the G1 and G2 groups is evidenced by a sample(R21) with a highly heterozygous genotype. Nucleotide diversity(π) analysis shows that G1 has a higher diversity than G2 and that G2 originated from G1. During the evolution process, the gene families involved in photosynthesis pathways expanded and the gene families involved in energy consumption contracted. RNA-seq data suggests that flavonoid biosynthesis and heat-shock protein(HSP)-heat-shock factor(HSF) pathways play important roles in protection against sunburn. This study provides new insights into the evolution of Sorbus spp.genomes. In addition, the genomic resources, and the identified genetic variations, especially those related to stress resistance, will help future efforts to produce and breed Sorbus spp.
基金supported by the National Key R&D Program of China(2019YFD0901805)the 111 Project(B18022)the Fundamental Research Funds for the Central Universities(22221818014).
文摘Biopolymer chitin and its derivatives have a wide range of applications in different fields.Chitin is primarily produced from marine crustacean by strong acid and strong alkali treatment.To reduce the environmental hazardous in the production of chitin,post-fermentation fungal biomass waste like fungi cell walls provides a viable alternative source for chitin.In this study,improved chitin content in yeast cell wall was achieved by overexpressing chitin biosyntheic pathway related genes.The chitin content was 51.5μg/mg cell wall and 122.9μg/mg cell wall in strain GS-1.10(gfat,uap and chs1 genes overexpression)and strain GS-2.6(gfat,gna1,agm1,uap and chs1 genes overexpression),which were 44.3%and 244.4%higher than that in control strain GS115,respectively.By overexpressing another chitin synthase gene(chs3),the chitin content in strain GS-3.10 was further increased to 136.2μg/mg cell wall,which was 10.8%and 281.6%higher than that in GS-2.6 and in control GS115,respectively.Moreover,chitin yield was further improved by various culture conditions optimization,and reached 162.4μg/mg cell wall,which was 4.43 times of that in the starting strain GS115.The final titer of chitin was 2.23 g/L culture broth in 84 h fed-batch fermentation in a 5 L bioreactor.To our knowledge,this is the first report of chitin production in engineered Pichia pastoris via biosynthetic pathway enhancement.