Here, we evaluate the contribution of two major biological processes--DNA replication and transcription--to mutation rate variation in human genomes. Based on analysis of the public human tissue transcriptomics data, ...Here, we evaluate the contribution of two major biological processes--DNA replication and transcription--to mutation rate variation in human genomes. Based on analysis of the public human tissue transcriptomics data, high-resolution replicating map of Hela cells and dbSNP data, we present significant correlations between expres- sion breadth, replication time in local regions and SNP density. SNP density of tissue-specific （TS） genes is sig- nificantly higher than that of housekeeping （HK） genes. TS genes tend to locate in late-replicating genomic re- gions and genes in such regions have a higher SNP density compared to those in early-replication regions. In addi- tion, SNP density is found to be positively correlated with expression level among HK genes. We conclude that the process of DNA replication generates stronger mutational pressure than transcription-associated biological processes do, resulting in an increase of mutation rate in TS genes while having weaker effects on HK genes. In contrast, transcription-associated processes are mainly responsible for the accumulation of mutations in highly-expressed HK genes.展开更多
Casein is rich in bioactive peptides,but most of them are inactive in native casein.Microbial fermentation has been considered as an effective method to release bioactive peptides using their powerful and strain-speci...Casein is rich in bioactive peptides,but most of them are inactive in native casein.Microbial fermentation has been considered as an effective method to release bioactive peptides using their powerful and strain-specific proteolysis system.In this paper,the structural characteristics and antioxidant activities of casein hydrolysates(CNHs)fermented by Lactiplantibacillus plantarum A56 and A157 were investigated.Both 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)(ABTS^(+))and hydroxyl radical results showed that CNHs demonstrated significantly enhanced radical scavenging ability compared to native casein,where the IC50 of ABTS^(+)and hydroxyl radical scavenging ability was 0.65 mg/mL(24h)and 2.97 mg/mL(24h)for A157 and 1.34 mg/mL(24h)and 3.33 mg/mL(24h)for A56.Furthermore,the native casein was hydrolyzed into small molecular peptides,15 or 16 kinds of free amino acid were identified in CNHs(7 for native casein),and the hydrolysis raised theα-helix andβ-turn rate,but reducedβ-sheet and random roil rate.In addition,cellular antioxidant experiments indicated that CNHs protected RAW264.7 cells against lipopolysaccharide(LPS)-induced oxidative damage,increased cell viability,elevated cellular superoxide dismutase(SOD)levels,decreased cellular reactive oxygen species(ROS)levels and inhibited mitochondrial membrane potential(MMP)decline.By searching and comparing the bioactive peptide databases,a variety of bioactive peptides with various bioactivities were found in the CNHs,such as antioxidant activity and immunomodulatory activity.These results suggested that the CNHs were with excellent antioxidant activity and contained many bioactive peptides and provided an effective way to produce bioactive peptides.展开更多
基金supported by grants from the National Basic Research Program (973 Program 2006CB9-10401 and 2006CB910403) awarded to JY and SH
文摘Here, we evaluate the contribution of two major biological processes--DNA replication and transcription--to mutation rate variation in human genomes. Based on analysis of the public human tissue transcriptomics data, high-resolution replicating map of Hela cells and dbSNP data, we present significant correlations between expres- sion breadth, replication time in local regions and SNP density. SNP density of tissue-specific （TS） genes is sig- nificantly higher than that of housekeeping （HK） genes. TS genes tend to locate in late-replicating genomic re- gions and genes in such regions have a higher SNP density compared to those in early-replication regions. In addi- tion, SNP density is found to be positively correlated with expression level among HK genes. We conclude that the process of DNA replication generates stronger mutational pressure than transcription-associated biological processes do, resulting in an increase of mutation rate in TS genes while having weaker effects on HK genes. In contrast, transcription-associated processes are mainly responsible for the accumulation of mutations in highly-expressed HK genes.
基金financially supported by the Basic Research Project of Free Exploration,Science and Technology Department of Jilin Province(YDZJ202201ZYTS688).
文摘Casein is rich in bioactive peptides,but most of them are inactive in native casein.Microbial fermentation has been considered as an effective method to release bioactive peptides using their powerful and strain-specific proteolysis system.In this paper,the structural characteristics and antioxidant activities of casein hydrolysates(CNHs)fermented by Lactiplantibacillus plantarum A56 and A157 were investigated.Both 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)(ABTS^(+))and hydroxyl radical results showed that CNHs demonstrated significantly enhanced radical scavenging ability compared to native casein,where the IC50 of ABTS^(+)and hydroxyl radical scavenging ability was 0.65 mg/mL(24h)and 2.97 mg/mL(24h)for A157 and 1.34 mg/mL(24h)and 3.33 mg/mL(24h)for A56.Furthermore,the native casein was hydrolyzed into small molecular peptides,15 or 16 kinds of free amino acid were identified in CNHs(7 for native casein),and the hydrolysis raised theα-helix andβ-turn rate,but reducedβ-sheet and random roil rate.In addition,cellular antioxidant experiments indicated that CNHs protected RAW264.7 cells against lipopolysaccharide(LPS)-induced oxidative damage,increased cell viability,elevated cellular superoxide dismutase(SOD)levels,decreased cellular reactive oxygen species(ROS)levels and inhibited mitochondrial membrane potential(MMP)decline.By searching and comparing the bioactive peptide databases,a variety of bioactive peptides with various bioactivities were found in the CNHs,such as antioxidant activity and immunomodulatory activity.These results suggested that the CNHs were with excellent antioxidant activity and contained many bioactive peptides and provided an effective way to produce bioactive peptides.
