:: Posted by American Biotechnologist on 03-24-2014
An international team led by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) has developed a new technique for identifying gene enhancers – sequences of DNA that act to amplify the expression of a specific gene – in the genomes of humans and other mammals. Called SIF-seq, for site-specific integration fluorescence-activated cell sorting followed by sequencing, this new technique complements existing genomic tools, such as ChIP-seq (chromatin immunoprecipitation followed by sequencing), and offers some additional benefits.
“While ChIP-seq is very powerful in that it can query an entire genome for characteristics associated with enhancer activity in a single experiment, it can fail to identify some enhancers and identify some sites as being enhancers when they really aren’t,” says Diane Dickel, a geneticist with Berkeley Lab’s Genomics Division and member of the SIF-seq development team. “SIF-seq is currently capable of testing only hundreds to a few thousand sites for enhancer activity in a single experiment, but can determine enhancer activity more accurately than ChIP-seq and is therefore a very good validation assay for assessing ChIP-seq results.”
Dickel is the lead author of a paper in Nature Methods describing this new technique. The paper is titled “Function-based identification of mammalian enhancers using site-specific integration.”
:: Posted by American Biotechnologist on 03-18-2014
Our genome, we are taught, operates by sending instructions for the manufacture of proteins from DNA in the nucleus of the cell to the protein-synthesizing machinery in the cytoplasm. These instructions are conveyed by a type of molecule called messenger RNA (mRNA).
Francis Crick , co-discoverer of the structure of the DNA molecule, called the one-way flow of information from DNA to mRNA to protein the “central dogma of molecular biology.”
Yehuda Ben-Shahar and his team at Washington University in St. Louis have discovered that some mRNAs have a side job unrelated to making the protein they encode. They act as regulatory molecules as well, preventing other genes from making protein by marking their mRNA molecules for destruction.
“Our findings show that mRNAS, which are typically thought to act solely as the template for protein translation, can also serve as regulatory RNAs, independent of their protein-coding capacity,” Ben-Shahar said. “They’re not just messengers but also actors in their own right.” The finding was published in the March 18 issue of the new open-access journal eLife.
Although Ben-Shahar’s team, which included neuroscience graduate student Xingguo Zheng and collaborators Aaron DiAntonio and his graduate student Vera Valakh, was studying heat stress in fruit flies when they made this discovery, he suspects this regulatory mechanism is more general than that.
Many other mRNAs, including ones important to human health, will be found to be regulating the levels of proteins other than the ones they encode. Understanding mRNA regulation may provide new purchase on health problems that haven’t yielded to approaches based on Crick’s central dogma.
Read the full story A novel mechanism for fast regulation of gene expression.
:: Posted by American Biotechnologist on 11-18-2013
In developing nations, rural areas, and even one’s own home, limited access to expensive equipment and trained medical professionals can impede the diagnosis and treatment of disease. Many qualitative tests that provide a simple “yes” or “no” answer (like an at-home pregnancy test) have been optimized for use in these resource-limited settings. But few quantitative tests—those able to measure the precise concentration of biomolecules, not just their presence or absence—can be done outside of a laboratory or clinical setting. By leveraging their discovery of the robustness of “digital,” or single-molecule quantitative assays, researchers at the California Institute of Technology (Caltech) have demonstrated a method for using a lab-on-a-chip device and a cell phone to determine a concentration of molecules, such as HIV RNA molecules, in a sample. This digital approach can consistently provide accurate quantitative information despite changes in timing, temperature, and lighting conditions, a capability not previously possible using traditional measurements.
:: Posted by American Biotechnologist on 11-08-2013
One of biology’s most fundamental processes is something called transcription. It is just one step of many required to build proteins—and without it life would not exist. However, many aspects of transcription remain shrouded in mystery. But now, scientists at the Gladstone Institutes are shedding light on key aspects of transcription, and in so doing are coming even closer to understanding the importance of this process in the growth and development of cells—as well as what happens when this process goes awry.
In the latest issue of Molecular Cell, researchers in the laboratory of Gladstone Investigator Melanie Ott, MD, PhD, describe the intriguing behavior of a protein called RNA polymerase II (RNAPII). The RNAPII protein is an enzyme, a catalyst that guides the transcription process by copying DNA into RNA, which forms a disposable blueprint for making proteins. Scientists have long known that RNAPII appears to stall or “pause” at specific genes early in transcription. But they were not sure as why.
Read more …
:: Posted by American Biotechnologist on 10-17-2013
Duke researchers have connected very rare and precise duplications and deletions in the human genome to their complex disease consequences by duplicating them in zebrafish.
The findings are based on detailed studies of five people missing a small fragment of their genome and suffering from a mysterious syndrome of craniofacial features, visual anomalies and developmental delays.
When those patient observations were coupled to analyses of the anatomical defects in genetically altered zebrafish embryos, the researchers were able to identify the contribution specific genes made to the pathology, demonstrating a powerful tool that can now be applied to unraveling many other complex and rare human genetic conditions.
The findings are broadly important for human genetic disorders because copy-number variants (CNVs) — fragments of the genome that are either missing or existing in extra copies — are quite common in the genome. But their precise contribution to diseases has been difficult to determine because CNVs can affect the function of many genes simultaneously.