36 results about "Double crossover" patented technology

Robust nucleic acid arrays and lattices are assembled based on double crossover cohesion of polygonal units whose edges are composed of nucleic acid multi-crossover domains.

The invention discloses a method of performing traceless knockout on a chromogene or inserting an exogenous gene in a chromosome of Acidithiobacillus caldus. The method comprises the following steps: transferring a homologous recombinant plasmid containing plentiful restriction enzyme digestion sites of endonuclease I-SceI into the Acidithiobacillus caldus in a conjugation transfer manner, simultaneously, directionally inserting the homologous recombinant plasmid into the chromosome of Acidithiobacillus caldus by use of a homologous recombinant system of a cell itself, transferring a screenedsingle crossover to an I-SceI expression plasmid by an electroporation method, performing secondary homologous recombination on a single recon chromosome under a stress that the I-SceI enzyme cuts the chromosome, and optimizing and screening a double crossover bacterial strain to realize knockout and insertion of the gene. The invention also constructs a suicide type plasmid vector pSDUDI for homologous recombination and a plasmid pSDU1-I-SceI for expressing the I-SceI enzyme effectively, and provides convenience for the traceless knockout and the integration of the chromogene in the Acidithiobacillus caldus. The method provided by the invention provides a new way for intensive study on and modification of Acidithiobacillus caldus.

A crossover for travel paths is provided. The crossover includes a primary travel path having a first pathway arranged for travel in a first direction and a second pathway arranged for travel in a second direction, and a secondary travel path having a third pathway arranged for travel in a third direction and a fourth pathway arranged for travel in a fourth direction. A main bridge crossover is provided so that the first and second pathways cross each of the third and fourth pathways without intersecting at grade. Two minor bridge crossovers are provided, each constructed and arranged so that the third and fourth pathways cross each other without intersecting, at grade. Lane communication is provided between select exits and entrances to minimize weaving traffic patterns, additional flyovers are minimized and no 270-degree loops are required, providing continuous traffic flow.

The invention relates to an urban railway double-crossover middle turning device and a method for eliminating lateral bending and upwarping of a beam body. A butt joint part between a first rotary beam and a second rotary beam is of a lug boss lap-joint structure and is located on a base through a rotary table, the lower part of a non-butt-joint part of each of the first rotary beam and the second rotary beam is provided with a trolley moving mechanism, the trolley moving mechanisms are located on bases, a drive guide slot is arranged at the bottom of each of the first rotary beam and the second rotary beam, one ends of two drive arms are respectively located in the drive guide slots, the other ends of the two drive arms are respectively connected with a power output end of a respective reduction gear, the power input ends of the reduction gears are respectively connected with a power output end of a double-end motor reduction gear through a transmission shaft and a transmission shaft support frame, two locking frames are respectively located on the bases for supporting the non-butt-joint parts of the first rotary beam and the second rotary beam, and two locking mechanisms are respectively located at the back parts of the non-butt-joint parts of the first rotary beam and the second rotary beam and are respectively matched with the locking frames in a locking or opening manner.

The invention relates to a method for the simultanoues integration of two or more copies of a polynucleotide of interest into the chromosome of a fungal host cell comprising at least two pairs of recognition sequences of a site-specific recombinase, each pair flanking a resident negative selection marker; transformation of the cell with a construct carrying a gene of interest also flanked by the recognition sequences to ensure double-crossover events after transient expression of the recombinase, followed by selection for excision of all negative selection markers from the cell.

The invention discloses a rail transit turn-round track arrangement structure comprising a rail running area and rail main tracks laid on the rail running area. The rail main tracks comprise a first rail and a second rail which are arranged side by side. A first single crossover and a second single crossover are further arranged between the first rail and the second rail. The first single crossover is arranged in front of a station, and the second single crossover is arranged on the back of the station. The first single crossover and the second single crossover are used for achieving switch between the first rail and the second rail when a train is in front of the station and/or on the back of the station and can also be used for turning round at the same time. According to the rail transit turn-round track structure, the two single crossovers are mutually standby, when one single crossover breaks down, use of the other single crossover is not influenced, and therefore the reliabilityand operation efficiency of the train are effectively improved; and the technical problem that in the prior art, double crossovers are adopted and are not beneficial for rail operation stability, andthe single-side station train operation efficiency is low are solved.

The invention discloses a double crossover switch suitable for a tramcar and subway vehicle debugging workshop, which comprises a first main rail, a second main rail, a first switch rail and a secondswitch rail, wherein the first main rail and the second main rail are parallel, the first switch rail and the second switch rail form a rhombic cross at an intersection, the first switch rail and thesecond switch rail are respectively intersected with the first main rail and the second main rail to form four single-opening switches, and each single-opening switch comprises a switch device, a frogand a guard rail; a distance L between the two main rails is 8,000 mm, the switch rails comprise arc-shaped guide curved rails and straight rails, the main rails and the switch rails meet each otherthrough the guide curved rails, and a radius R of the guide curved rails is equal to 25,000 mm; the switch device comprises a straight basic rail, a curved basic rail, a first point rail matched withthe straight basic rail and a second point rail matched with the curved basic rail; a frog angle of the single-opening switch equals to 22o19' 16''; and the guard rail comprises a first guard rail anda second guard rail. The double crossover switch suitable for the tramcar and subway vehicle debugging workshop has the advantage of small occupied area.

The invention discloses a multi-gene stacking knockout method for bacillus. The multi-gene stacking knockout method includes: inserting homologous arm gene segments of upstream and downstream of multiple genes to be knocked out of the bacillus into thermo-sensitive type plasmids to convert the bacillus, forcing homologous single-crossover to happen to knockout plasmids in the bacillus and genome DNA (deoxyribose nucleic acid) of the knockout plasmids through high-temperature culture, and screening double-crossover bacterial strains through high-temperature subculture; extracting the genome DNAs of the multiple bacterial strains successful in gene single-crossover, performing double-crossover screening, stacking the bacterial strains successful in knockout as host strains for the nest round of stacking knockout, and sequentially stacking to finally realize multi-gene knockout of the bacillus. Traceless gene knockout of the bacillus is realized with the thermo-sensitive type plasmids, conversion efficiency can be improved by using the single-crossover hose genome DNAs to convert the bacillus, restoration of the knockout genes in the host strains can be effectively avoided, and multi-gene stacking knockout efficiency is remarkably improved.

The invention discloses a high-yield G418 engineering strain, and a construction method and application thereof, and belongs to the field of antibiotic pharmacy. The high-yield G418 engineering strain is micromonospora echinospora deficient of a function of a gene genQ for encoding C-6' hydroxyl oxido-reductase, and the preservation number of the high-yield G418 engineering strain is CCTCCNO: M2013729. The construction method comprises the step of deleting the gene genQ from the micromonospora echinospora by using an in-frame deletion method, and comprises construction of genQ gene in-frame deletion plasmids, transformation of the micromonospora echinospora with the in-frame deletion plasmids and screening of a double-crossover mutant strain. According to the high-yield G418 engineering strain, and the construction method and application thereof, an in-frame deletion technology is used for deleting the gene genQ from the gentamicin producing strain micromonospora echinospora to block the synthesis of a component C of gentamicin and a related intermediate product and mainly generate G418; the G418 DeltagenQ is high in yield and purity, a production process for the G418 is simplified, and the production cost is lowered.

The invention discloses a control method for a motor vehicle application station system, and belongs to the field of motor vehicle applications. The motor vehicle application station system is a double-layer operating system, an underground floor is provided with an underground parking lot, the underground parking lot is provided with an underground parking lot throat area, and an over-ground floor and the underground floor are connected through tracks in a ramp mode; the over-ground floor comprises an over-ground parking lot, an inspecting shop line, a moving line, a lead track, a double crossover, a vehicle washing track, a travelling line, temporary repairing and under-floor wheel lathe line and a middle throat, a double crossover is further arranged at the middle throat, the control method for the motor vehicle application station system comprises the method of entering the station through the underground floor, upper and lower floor transition method in the station and the methodof entering the station through the over-ground floor. The control method for the motor vehicle application station system fully utilizes the underground space and effectively solves the problems thatan existing motor vehicle application station is small in occupied area and large in vehicle storing number.

The invention discloses gentamycin JI-20B gene engineering bacterium, and construction and application thereof, and belongs to the technical field of biological medicine. Gentamycin JI-20B is directionally synthesized by constructing specific shuttle vector pFD605, utilizing molecular genetics technology to introduce micromonospora, accurately knocking out genB3 gene and genP gene in Micromonospora purpurea by means of frame deletion principle, and permanently inactivating the biological catalysis function of Micromonospora purpurea, utilizing a resistance marker to screen double-crossover mutant strain MicromonosporapurpureaB3P1220 (delta genB3P(gntJI)), performing fermentation on the mutant strain, extracting metabolite, performing structure analysis, and determining that the structure is anastomotic with that of prediction. The constructed engineering bacterium B3P1200 contains no any resistankt markers and the output of gentamycin JI-20B is stable.

The invention relates to a method of double crossover homologous recombination in a host Clostridia cell comprising: a first homologous recombination event between a donor DNA molecule and DNA of the host cell to form a product of the first recombination event in the host cell, wherein the donor DNA molecule comprises a codA gene and at least two homology arms; and a second recombination event within the product of the first homologous recombination event, thereby to form a product of the second homologous recombination event in the host cell which is selectable by the loss of the codA gene; and a related vector and altered host cell.

The present invention is directed to a sequence dependent polynucleotide nanomechanical device based on a nucleic acid paranemic crossover (PX) molecule which is a four-stranded structure related to parallel double crossover molecules, except that every possible crossover takes place. Eliminating two crossovers leads to a topoisomer, termed JX₂, in which one pair of ends are switched (rotated 180°) while the other pair of ends remain the same. The device can be cycled between the two states, PX and JX₂, by replacing single strands that set the state to be PX or JX₂.

The invention provides a gene of coded 6-phosphogluconate dehydrogenase and application thereof. The nucleotide sequence is shown in SEQ ID NO:1. The 6-phosphogluconate dehydrogenase gene pgdhD2 is derived from Methylobacterium sp. MB200 and has the L-serine inhibiting effect. The Methylobacterium sp. MB200 is used as an original strain, pgdh gene deletion mutation DMB is built through a homologous double-crossover method, an L-serine high-yield mutant strain with the L-serine producing capacity greatly higher than that of original strain Methylobacterium sp. MB200 is obtained, and the tolerated D-serine concentration of the L-serine high-yield mutant strain is greatly higher than that of the original strain. The pgdh gene deletion mutation stain has the good application prospect in production of L-serine through a fermentation method.

The present method is useful for the identification of genes, ORF's and other nucleic acid molecules which are essential for the expression of a specific phenotype in microorganisms. The method employs in vitro transposition in conjunction with an chromosomal integration vector containing a specific gene or genetic element whose function is unknown. Subsequent transformation of a recombination proficient host with the vector and growth first under non-integrating conditions and then under integrating conditions, followed by a selection screen for either single or double crossover events results in transformation that may be subjected to phenotypic screens to determine gene function.

The invention discloses a railway existing double crossover integral insertion and pavement construction method. The method comprises the following steps that 1, a pre-paving site is selected; 2, a double crossover is paved in advance, and control piles on the two sides of the double crossover are rechecked and accepted; 3, the double crossover is reinforced; and 4, double crossover sliding ways are arranged, the double crossover is integrally inserted and laid in place, an existing line in the inserting range is detached according to the design position in the skylight point, a ballast bed iscleared, the double crossover is slowly and transversely moved forwards, and the force of each part is guaranteed to be uniform. Compared with railway existing double crossover disintegration insertion and pavement, double crossover integral insertion and pavement is adopted, so that the number of the skylights is saved, the influence on normal transportation of the railway is reduced, the construction period is short, the efficiency is high, the overall structural size of the double crossover after being inserted is good, the diseases are few, the later maintenance cost is greatly reduced, the railway transportation is safe and reliable, the economic benefit is obvious, and the method can be widely popularized and used.