Laban jameed is a dried salty dairy product obtained by fermentation of milk using a complex population of lactic acid bacteria. Jameed is considered a traditional food product in most eastern Mediterranean countries ...Laban jameed is a dried salty dairy product obtained by fermentation of milk using a complex population of lactic acid bacteria. Jameed is considered a traditional food product in most eastern Mediterranean countries and is usually made from sheep or cow milk. The aim of this study was to assess phage contamination of jameed dairy product. Two phages were isolated: one from sheep milk jameed (PPUDV) and the other from cow milk jameed (PPURV). Each of the two bacteriophages was partially characterized. The PPUDV phage was identified as a single stranded DNA virus with an approximately 20 kb genome that was resistant to RNase, whereas PPURV phage possessed a double stranded RNA genome of approximately 20 kb and was resistant to DNase. The phage bacterial strain hosts were identified as Lactobacillus helveticus and Bacillus amyloliquefaciens for PPUDV and PPURV, respectively. One step growth curve using a double layer plaque assay test was carried out to monitor the phage life cycle after host infection. PPUDV showed a latent period of about 36 h, burst period of 70 h and a burst size of about 600 Plaque Forming Units (PFU) per infected cell. PPURV phage showed a latent period of about 24 h, burst period of 47 h and a burst size of about 700 PFU per infected cell. SDS-PAGE analysis of total viral proteins showed at least three major bands (27, 40, and 45 kDa) for PPUDV. This is the first study to report the isolation of both DNA and RNA bacteriophages from laban jameed. This study adds new insights into the complexity of dairy contamination and fermentation microbiology of the jameed revealing the existence of two viral genomes in this highly dried and salty dairy product.展开更多
Gene-silencing siRNA has shown great promise for the treatment of genetic diseases,cancers,and viral infections,but its therapeutic value has been hindered by the lack of an efficient and safe in vivo delivery system ...Gene-silencing siRNA has shown great promise for the treatment of genetic diseases,cancers,and viral infections,but its therapeutic value has been hindered by the lack of an efficient and safe in vivo delivery system to target specific cells.The motor pRNA of phi29 has a strong tendency to form dimers,trimers and hexamers by interaction of interlocking right and left hand loops.This unique feature makes pRNA an ideal vector for the delivery of multiple therapeutic RNAs.Toxicity of pRNA was detected by transfection of 8 pRNA in HeLa cells.A pRNA-based vector was designed to carry siRNAs to inhibit GFP or HBV surface gene expression.Silence effects on siRNA against expression of GFP or HBV surface gene were detected in HeLa cells.Viral replicative intermediates were detected by Southern blotting.The results of toxicity study showed there was no toxicity of pRNA to cultured monolayer cells.The siRNA connected with pRNA can inhibit GFP or HBV surface gene expression in HeLa cells and inhibit HBV replication in HepG2 cells.These data suggest that pRNA can be used as a vector for imparting stability to siRNA in vitro.展开更多
As the most abundant biological entities with incredible diversity,bacteriophages(also known as phages)have been recognized as an important source of molecular machines for the development of genetic-engineering tools...As the most abundant biological entities with incredible diversity,bacteriophages(also known as phages)have been recognized as an important source of molecular machines for the development of genetic-engineering tools.At the same time,phages are crucial for establishing and improving basic theories of molecular biology.Studies on phages provide rich sources of essential elements for synthetic circuit design as well as powerful support for the improvement of directed evolution platforms.Therefore,phages play a vital role in the development of new technologies and central scientific concepts.After the RNA world hypothesis was proposed and developed,novel biological functions of RNA continue to be discovered.RNA and its related elements are widely used in many fields such as metabolic engineering and medical diagnosis,and their versatility led to a major role of RNA in synthetic biology.Further development of RNA-based technologies will advance synthetic biological tools as well as provide verification of the RNA world hypothesis.Most synthetic biology efforts are based on reconstructing existing biological systems,understanding fundamental biological processes,and developing new technologies.RNA-based technologies derived from phages will offer abundant sources for synthetic biological components.Moreover,phages as well as RNA have high impact on biological evolution,which is pivotal for understanding the origin of life,building artificial life-forms,and precisely reprogramming biological systems.This review discusses phage-derived RNA-based technologies terms of phage components,the phage lifecycle,and interactions between phages and bacteria.The significance of RNA-based technology derived from phages for synthetic biology and for understanding the earliest stages of biological evolution will be highlighted.展开更多
文摘Laban jameed is a dried salty dairy product obtained by fermentation of milk using a complex population of lactic acid bacteria. Jameed is considered a traditional food product in most eastern Mediterranean countries and is usually made from sheep or cow milk. The aim of this study was to assess phage contamination of jameed dairy product. Two phages were isolated: one from sheep milk jameed (PPUDV) and the other from cow milk jameed (PPURV). Each of the two bacteriophages was partially characterized. The PPUDV phage was identified as a single stranded DNA virus with an approximately 20 kb genome that was resistant to RNase, whereas PPURV phage possessed a double stranded RNA genome of approximately 20 kb and was resistant to DNase. The phage bacterial strain hosts were identified as Lactobacillus helveticus and Bacillus amyloliquefaciens for PPUDV and PPURV, respectively. One step growth curve using a double layer plaque assay test was carried out to monitor the phage life cycle after host infection. PPUDV showed a latent period of about 36 h, burst period of 70 h and a burst size of about 600 Plaque Forming Units (PFU) per infected cell. PPURV phage showed a latent period of about 24 h, burst period of 47 h and a burst size of about 700 PFU per infected cell. SDS-PAGE analysis of total viral proteins showed at least three major bands (27, 40, and 45 kDa) for PPUDV. This is the first study to report the isolation of both DNA and RNA bacteriophages from laban jameed. This study adds new insights into the complexity of dairy contamination and fermentation microbiology of the jameed revealing the existence of two viral genomes in this highly dried and salty dairy product.
文摘Gene-silencing siRNA has shown great promise for the treatment of genetic diseases,cancers,and viral infections,but its therapeutic value has been hindered by the lack of an efficient and safe in vivo delivery system to target specific cells.The motor pRNA of phi29 has a strong tendency to form dimers,trimers and hexamers by interaction of interlocking right and left hand loops.This unique feature makes pRNA an ideal vector for the delivery of multiple therapeutic RNAs.Toxicity of pRNA was detected by transfection of 8 pRNA in HeLa cells.A pRNA-based vector was designed to carry siRNAs to inhibit GFP or HBV surface gene expression.Silence effects on siRNA against expression of GFP or HBV surface gene were detected in HeLa cells.Viral replicative intermediates were detected by Southern blotting.The results of toxicity study showed there was no toxicity of pRNA to cultured monolayer cells.The siRNA connected with pRNA can inhibit GFP or HBV surface gene expression in HeLa cells and inhibit HBV replication in HepG2 cells.These data suggest that pRNA can be used as a vector for imparting stability to siRNA in vitro.
基金This work was financially supported by National Key Research and Development Project of China(Grant No.2018YFA0900103)International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.31961133019)National Natural Science Foundation of China(Grant No.31670991).
文摘As the most abundant biological entities with incredible diversity,bacteriophages(also known as phages)have been recognized as an important source of molecular machines for the development of genetic-engineering tools.At the same time,phages are crucial for establishing and improving basic theories of molecular biology.Studies on phages provide rich sources of essential elements for synthetic circuit design as well as powerful support for the improvement of directed evolution platforms.Therefore,phages play a vital role in the development of new technologies and central scientific concepts.After the RNA world hypothesis was proposed and developed,novel biological functions of RNA continue to be discovered.RNA and its related elements are widely used in many fields such as metabolic engineering and medical diagnosis,and their versatility led to a major role of RNA in synthetic biology.Further development of RNA-based technologies will advance synthetic biological tools as well as provide verification of the RNA world hypothesis.Most synthetic biology efforts are based on reconstructing existing biological systems,understanding fundamental biological processes,and developing new technologies.RNA-based technologies derived from phages will offer abundant sources for synthetic biological components.Moreover,phages as well as RNA have high impact on biological evolution,which is pivotal for understanding the origin of life,building artificial life-forms,and precisely reprogramming biological systems.This review discusses phage-derived RNA-based technologies terms of phage components,the phage lifecycle,and interactions between phages and bacteria.The significance of RNA-based technology derived from phages for synthetic biology and for understanding the earliest stages of biological evolution will be highlighted.
