A first attempt has been made to confirm experimentally a theoretical concept, recently published, involving a rigid cone rotating about its long axis under still water: it should tend to translate along that axis blu...A first attempt has been made to confirm experimentally a theoretical concept, recently published, involving a rigid cone rotating about its long axis under still water: it should tend to translate along that axis blunt end leading and apex trailing. Two identical hollow cones, neutrally buoyant, with equal weights attached to the apexes, were released simultaneously at the surface of a swimming pool. One cone had a thin light weight spiral vane vertically attached to the cone’s outside surface in order to cause it to rotate as it sank. Several trial runs were made in the shallow and deep ends of the pool, and in every case, the non-rotating cone without a vane hit the bottom of the pool first. These comparisons qualitatively and indirectly validate the prediction.展开更多
Introducing PCR products into plasmids vectors is key for molecular techniques. Ideally cloning vectors are easy to construct, modify and propagate, neither require advanced techniques nor special equipment or reagent...Introducing PCR products into plasmids vectors is key for molecular techniques. Ideally cloning vectors are easy to construct, modify and propagate, neither require advanced techniques nor special equipment or reagents and efficiently incorporate PCR products at close to zero empty vector background. We provide an easy to engineer self-made cloning vector, neither requiring sophisticated tools or techniques nor advanced cloning knowledge. Through recombination we obtained the pUC18ccdB vector, carrying the ccdB suicide gene within the pUC18 backbone. When SmaI cleaved (within the ccdB) vector was T4 ligated with small (0.2 kbp) and intermediate (1.3 to 2.2 kbp) blunt end PCR-products and transformed into E. coli, the amount of clones with incorporated PCR product was comparable to commercial PCR-cloning kits and at a close to zero PCR product negative background. In conclusion we present a simple, versatile and cheap approach to an efficient “home made” PCR-cloning vector that allows integration of crude blunt end PCR products at close to zero background.展开更多
文摘A first attempt has been made to confirm experimentally a theoretical concept, recently published, involving a rigid cone rotating about its long axis under still water: it should tend to translate along that axis blunt end leading and apex trailing. Two identical hollow cones, neutrally buoyant, with equal weights attached to the apexes, were released simultaneously at the surface of a swimming pool. One cone had a thin light weight spiral vane vertically attached to the cone’s outside surface in order to cause it to rotate as it sank. Several trial runs were made in the shallow and deep ends of the pool, and in every case, the non-rotating cone without a vane hit the bottom of the pool first. These comparisons qualitatively and indirectly validate the prediction.
文摘Introducing PCR products into plasmids vectors is key for molecular techniques. Ideally cloning vectors are easy to construct, modify and propagate, neither require advanced techniques nor special equipment or reagents and efficiently incorporate PCR products at close to zero empty vector background. We provide an easy to engineer self-made cloning vector, neither requiring sophisticated tools or techniques nor advanced cloning knowledge. Through recombination we obtained the pUC18ccdB vector, carrying the ccdB suicide gene within the pUC18 backbone. When SmaI cleaved (within the ccdB) vector was T4 ligated with small (0.2 kbp) and intermediate (1.3 to 2.2 kbp) blunt end PCR-products and transformed into E. coli, the amount of clones with incorporated PCR product was comparable to commercial PCR-cloning kits and at a close to zero PCR product negative background. In conclusion we present a simple, versatile and cheap approach to an efficient “home made” PCR-cloning vector that allows integration of crude blunt end PCR products at close to zero background.
