Tag: 2020换7群

Enzymatic DNA synthesis sees the light

first_img The genetics of regeneration Critical step found in DNA repair, cellular aging “This new approach to enzyme-directed synthetic DNA synthesis by the Church team is a clever piece of bioinspired engineering that combines the power of DNA replication with one of the most controllable and robust manufacturing methods developed by humanity — photolithography — to provide a solution that brings us closer to the goal of establishing DNA as a usable data storage medium,” said the Wyss Institute’s Founding Director Don Ingber, who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, and Professor of Bioengineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). Other authors on the study are additional members of Church’s team, including Kettner Griswold, and Sukunya Punthambaker, as well as Honggu Chun, Professor of Biomedical Engineering at Korea University. This work was funded by the Wyss Institute for Biologically Inspired Engineering. DNA helicopters offer insight into how biological machines power living things A new spin on an old question Experiments in mice suggest way to thwart DNA damage from aging, radiation Study uncovers genes that control process of whole-body regeneration According to current estimates, the amount of data produced by humans and machines is rising at an exponential rate, with the digital universe doubling in size every two years. Very likely, the magnetic and optical data-storage systems at our disposal won’t be able to archive this fast-growing volume of digital 1s and 0s anymore at some point. Plus, they cannot safely store data for more than a century without degrading.  One solution to this pending global data-storage problem could be the development of DNA — life’s very own information-storage system — into a digital data storage medium. Researchers already are encoding complex information consisting of digital code into DNA’s four-letter code comprised of its A, T, G, and C nucleotide bases. DNA is an ideal storage medium because it is stable over hundreds or thousands of years, has an extraordinary information density, and its information can be efficiently read (decoded) again with advanced sequencing techniques that are continuously getting less expensive.What lags behind is the ability to write (encode) information into DNA. The programmed synthesis of synthetic DNA sequences still is mostly performed with a decades-old chemical procedure, known as the “phosphoramidite method,” that takes many steps that, although being able to be multiplexed, can only generate DNA sequences with up to around 200 nucleotides in length and makes occasional errors. It also produces environmentally toxic by-products that are not compatible with a “clean data storage technology.”Previously, George Church’s team at Harvard’s Wyss Institute for Biologically Inspired Engineering and Harvard Medical School (HMS) has developed the first DNA storage approach that uses a DNA-synthesizing biological enzyme known as Terminal deoxynucleotidyl Transferase (TdT), which, in principle, can synthesize much longer DNA sequences with fewer errors. Now, the researchers have applied photolithographic techniques from the computer chip industry to enzymatic DNA synthesis, and thus developed a new method to multiplex TdT’s superior DNA writing ability. In their study published in Nature Communications, they demonstrated the parallel synthesis of 12 DNA strands with varying sequences on a 1.2 square millimeter array surface. “We have championed and intensively pursued the use of DNA as a data-archiving medium accessed infrequently, yet with very high capacity and stability. Breakthroughs by us and others have enabled an exponential rise in the amount of digital data encrypted in DNA,” said corresponding author Church. “This study and other advances in enzymatic DNA synthesis will push the envelope of DNA writing much further and faster than chemical approaches.” Church is a core faculty member at the Wyss Institute and lead of its Synthetic Biology Focus Area with DNA data storage as one of its technology development areas. He also is professor of genetics at HMS and Professor of Health Sciences and Technology at Harvard and MIT.  While the group’s first strategy using the TdT enzyme as an effective tool for DNA synthesis and digital data storage controlled TdT’s enzyme activity with a second enzyme, they show in their new study that TdT can be controlled by the high-energy photons that UV-light is composed of. A high level of control is essential as the TdT enzyme needs to be instructed to add only one single or a short block made of one of the four A, T, G, C nucleotide bases to the growing DNA strand with high precision at each cycle of the DNA synthesis process.,Using a special codec, a computational method that encodes digital information into DNA code and decodes it again, which Church’s team developed in their previous study, the researchers encoded the first two measures of the “Overworld Theme” sheet music from the 1985 Nintendo Entertainment System (NES) video game Super Mario Brothers within 12 synthetic DNA strands. They generated those strands on an array matrix with a surface measuring merely 1.2 square millimeters by extending short DNA “primer” sequences, which were extended in a 3×4 pattern, using their photolithographic approach. “We applied the same photolithographic approach used by the computer chip industry to manufacture chips with electrical circuits patterned with nanometer precision to write DNA,” said first author Howon Lee, a postdoctoral fellow in Church’s group at the time of the study. “This provides enzymatic DNA synthesis with the potential of unprecedented multiplexing in the production of data-encoding DNA strands.”Photolithography, like photography, uses light to transfer images onto a substrate to induce a chemical change. The computer chip industry miniaturized this process and uses silicon instead of film as a substrate. Church’s team now adapted the chip industry’s capabilities in their new DNA writing approach by substituting silicon with their array matrix consisting of microfluidic cells containing the short DNA primer sequences. In order to control DNA synthesis at primers positioned in the 3×4 pattern, the team directed a beam of UV-light onto a dynamic mask (as is done in computer chip manufacturing) — which essentially is a stencil of the 3×4 pattern in which DNA synthesis is activated — and shrunk the patterned beam on the other side of the mask with optical lenses down to the size of the array matrix. “The UV-light reflected from the mask pattern precisely hits the target area of primer elongation and frees up cobalt ions, which the TdT enzyme needs in order to function, by degrading a light-sensitive “caging” molecule that shields the ions from TdT,” said co-author Daniel Wiegand, research scientist at the Wyss Institute. “By the time the UV-light is turned off and the TdT enzyme deactivated again with excess caging molecules, it has added a single nucleotide base or a homopolymer block of one of the four nucleotide bases to the growing primer sequences.”This cycle can be repeated multiple times whereby in each round only one of the four nucleotide bases or a homopolymer of a specific nucleotide base is added to the array matrix. In addition, by selectively covering specific openings of the mask during each cycle, the TdT enzyme only adds that specific nucleotide base to DNA primers where it is activated by UV-light, allowing the researchers to fully program the sequence of nucleotides in each of the strands.“Photon-directed multiplexed enzymatic DNA synthesis on this newly instrumented platform can be further developed to enable much higher automated multiplexing with improved TdT enzymes, and, eventually make DNA-based data storage significantly more effective, faster, and cheaper,” said co-corresponding author Richie Kohman, a lead senior research scientist at the Wyss’ Synthetic Biology focus area, who helped coordinate the research in Church’s team at the Wyss Institute. Relatedlast_img read more

February bar exam results posted

first_imgFebruary bar exam results posted April 30, 2006 Regular News February bar exam results postedcenter_img Graduates from Florida State University had the highest passage rate for those taking the February Florida bar exam.The Florida Board of Bar Examiners released the results from the February bar exam April 17.A total of 1,035 people took the exam, 538 from out-of-state and the remainder in-state graduates. The FBBE also said 899 took the Multistate Professional Responsibility Exam in March, 360 from out-of-state and the remainder from the 10 Florida law schools.FSU topped those who took Part A and Part B of the general bar exam; 31 of the 34 FSU grads passed, or 91.2 percent. The University of Florida was next, with 131 of its 150 graduates passing, or 87.3 percent. Next was Florida International University, where 19 of 22 graduates passed, or 86.4 percent.Of the other law schools: 81 of the Stetson University’s 101 students passed the exam, or 80.2 percent; 45 of 58 graduates from Florida Coastal passed, or 77.6 percent; 18 of 26 students from the University of Miami passed, or 69.2 percent; 14 of 22 graduates from Barry University or Orlando passed, or 63.6 percent; 8 of 14 from Florida A&M passed, or 57.1 percent; 22 of 39 from Nova Southeastern University passed, or 56.4 percent; and 11 of 31 from St. Thomas University passed, or 35.5 percent.Three hundred and seventy-eight of the 538 applicants from out-of-state law schools passed, or 70.3 percent. Overall, 73.2 percent of those who took Parts A and B passed.That figure was 80.9 percent for the MPRE portion of the exam. Passage rates by school were 93.1 percent for UF; 91.8 percent the FSU; 91.2 percent for UM; 90.3 for Stetson; 90 percent for FIU; 78 percent for Florida Coastal; 74.6 percent for St. Thomas; 72.7 percent for FAMU; 61.3 percent for Barry; and 59.1 percent for NSU. The rate was 77.2 percent for out-of-state test takers.last_img read more

This Mermaid Beach home is a sanctuary with a unique design

first_img16 Petrel Avenue Mermaid Beach“Once you step outside the gate you realise how busy it all is, you have the beach on one side and Nobby’s on the other.“The home is a private sanctuary in the middle of it all.” More from news02:37Purchasers snap up every residence in the $40 million Siarn Palm Beach North11 hours ago02:37International architect Desmond Brooks selling luxury beach villa1 day agogc16 Petrel Avenue Mermaid BeachTimber stairs and floors combine with floor-to-ceiling glass walls and louvres to create a seamless integration between the inside and outside. Colourful contemporary interiors bring the layout to life while raked ceilings add to the ambience. 16 Petrel Avenue Mermaid Beach“I have counted that it is exactly 27 steps to my favourite coffee shop,” the father-of-three said. “It is the convenience that drew us to this place but the home has an incredible retro beach vibe. 16 Petrel Avenue Mermaid BeachThe study has a separate entrance from the courtyard. “I do a lot of work from home and it was a perfect second office that was a little bit detached from the living spaces,” he said. 16 Petrel Avenue Mermaid BeachSQUID tentacle sculptures, courtyard mirrors and a suspended stairwell create a sense of quirkiness at this strikingly beautiful Mermaid Beach home.The owner of mortgage broker service Blue Coast Finance, Paul Collis bought the four-bedroom home two years ago after he and his family moved from acreage property. gcb realestate 16 Petrel Avenue Mermaid Beach 9 February 2017“I hate to leave the house but my wife and I are expanding our family and we need another room.” 16 Petrel Avenue Mermaid Beach“There is something really quirky about it and I haven’t seen this type of design anywhere else on the Gold Coast.“I’m not a great big fan of Gold Coast homes but this one has character.”The home is filled with artwork and sculptures which Mr Collis bought from the local Gallery One. 16 Petrel Avenue Mermaid BeachOutside, an alfresco courtyard features vertical garden walls and a water feature.Mr Colllis, who moved from Sydney 12 years ago, said he loved the space the house offered.“I think this unique design really stands out,” Mr Collis said. last_img read more

Inter Snatch Real Madrid’s Hakimi on Five-year Deal

first_imgCrowds had gathered outside Inter’s headquarters to catch a glimpse of their new signing ahead of the defender sealing his move.Born in Madrid, Hakimi opted to represent the country of his parents at international level and to date has won 28 caps as well as representing Morocco at the 2018 World Cup.His performances for Dortmund this year, with 10 assists across 25 games, had put top European clubs on alert after he failed to agree a new deal with his parent club.Inter sit third in Serie A after the resumption of action and next host Brescia as they aim to closee the gap to the top.They are currently eight points from leaders Juventus with 10 games to play following an encouraging debut season for Antonio Conte.Share this:FacebookRedditTwitterPrintPinterestEmailWhatsAppSkypeLinkedInTumblrPocketTelegram Inter Milan have reportedly sealed the signing of Real Madridfull-back Achraf Hakimi on a five-year contract for an initial fee of £36million.The Moroccan international was spotted arriving in Milan to complete his medical ahead of sealing a move to Antonio Conte’s Serie A side amid interest from Premier League clubs including Chelsea and Manchester City.Hakimi, 21, made 17 appearances for Real Madrid but shot to prominence during a two-year loan spell with Borussia Dortmundthat brought 13 goals in 72 games.last_img read more