Two New Letters for the DNA Alphabet. Scientists keep getting better at rewriting the book of life. Adding, deleting, and splicing genes has become routine, and some researchers are now even designing DNA for creatures. While many are hard at work rearranging letters on the page, a new experiment is redefining the concept of synthetic biology by writing new letters.
As they reported today in the journal Nature, a team of biologists led by Floyd Romesberg at the Scripps Research Institute have expanded the genetic alphabet of DNA—the As, Cs, Gs, and Ts that write the book of life—to include two new letters. The scientists showed that their letters could be integrated into the DNA of a living creature (an E. coli bacterium) and increase exponentially the amount of information the genetic code can store. “This is a very major accomplishment in our efforts to inch towards a synthetic biology," says Steven Benner, a synthetic biologist at the Foundation for Applied Molecular Evolution who was not involved in the study. Failsafe. Scientists hail synthetic chromosome advance. 27 March 2014Last updated at 14:00 ET Yeast is a target for synthetic biologists because of its potential for future industrial applications Scientists have created the first synthetic chromosome for yeast in a landmark for biological engineering.
Previously synthetic DNA has been designed and made for simpler organisms such as bacteria. As a form of life whose cells contain a nucleus, yeast is related to plants and animals and shares 2,000 genes with us. So the creation of the first of yeast's 16 chromosomes has been hailed as "a massive deal" in the emerging science of synthetic biology. The genes in the original chromosome were replaced with synthetic versions and the finished manmade chromosome was then successfully integrated into a yeast cell. The new cell was then observed to reproduce, passing a key test of viability. One company in California has already used synthetic biology to create a strain of yeast that can produce artemisinin, an ingredient for an anti-malarial drug.
New tricks. Finding the needle in the haystack: Differentiating “identical” twins in paternity testing and forensics by ultra-deep next generation sequencing. Received 9 August 2013; received in revised form 24 October 2013; accepted 31 October 2013. Monozygotic (MZ) twins are considered being genetically identical, therefore they cannot be differentiated using standard forensic DNA testing. Here we describe how identification of extremely rare mutations by ultra-deep next generation sequencing can solve such cases.
We sequenced DNA from sperm samples of two twins and from a blood sample of the child of one twin. Bioinformatics analysis revealed five single nucleotide polymorphisms (SNPs) present in the twin father and the child, but not in the twin uncle. The SNPs were confirmed by classical Sanger sequencing. Our results give experimental evidence for the hypothesis that rare mutations will occur early after the human blastocyst has split into two, the origin of twins, and that such mutations will be carried on into somatic tissue and the germline. Keywords: Monozygotic identical twins, SNPs, Paternity testing. STRmix. Resolve more DNA mixtures | STRmix - Resolve more DNA mixtures. Traces of DNA Exposed by Twisted Light.
Structures that put a spin on light reveal tiny amounts of DNA with 50 times better sensitivity than the best current methods, a collaboration between the Univ. of Michigan and Jiangnan Univ. in China has shown. Highly sensitive detection of DNA can help with diagnosing patients, solving crimes and identifying the origins of biological contaminants such as a pathogen in a water supply. "It really does not matter where the target DNA is from," says Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of Chemical Engineering at U-M. "In order to detect a specific DNA, we just need to know a small portion of its sequence. " Current DNA analysis methods rely on copying segments of a strand of DNA. But if the primers were very selective for the suspected DNA sequence, then a match could be determined by simply detecting whether the DNA had copied or not. "Impressive detection limits were attained for short DNAs with nanoparticles; however, not for long DNA," Kotov says.
Microfluidic Technique Recovers DNA for IDs. A laboratory technician pipettes dirt dissolved in a buffer solution from which DNA will be recovered using a novel NIST/Applied Research Associates microfluidic extraction technique. The dirt, originally collected on a swab (lower section seen in vial) like those on the right, is an example of a crude sample from which DNA for human identification has typically been difficult to obtain.
Courtesy of Newman/NISTA team of researchers at the National Institute of Standards and Technology (NIST) and Applied Research Associates, Inc. (ARA, Alexandria, Va.) has demonstrated an improved microfluidic technique for recovering DNA from real-world, complex mixtures such as dirt. According to a recent paper, their technique delivers DNA from these crude samples with much less effort and in less time than conventional techniques. It yields DNA concentrations that are optimal for human identification procedures and can potentially be miniaturized for use outside the laboratory.