Scientists at the University of Virginia Health System have identified another step in the mysterious process of gene regulation -- what turns genes on or off, making them cause or suppress disease and other physical developments in humans. As reported in this week’s issue of the scientific journal Nature, a chemical group called ubiquitin has been shown to lie upstream of a switch that seems to control whether a gene is on or off. "Ubiquitin was first discovered on histones long ago, but before this study, we really did not know what it was doing in chromatin," said lead author and investigator Zu-Wen Sun, senior post-doctoral fellow in the Department of Biochemistry and Molecular Genetics at U.Va. Ubiquitin is one of manydistinct kinds of chemical "flags" that are known to be present on histone proteins.
Histones are protein building blocks around which the DNA is coiled much like a Slinky toy. Together, they form a structure called chromatin, where additional levels of gene regulation occur outside the DNA itself. One mechanism for regulating gene expression in the form of chromatin is through the addition or removal of chemical groups that are attached to the histone proteins. These histone proteins are nearly identical in most complex living organisms, from humans to yeast, which was used as a model in this study. They are highly decorated with different kinds of chemical groups including methyl- and acetyl- groups. Distinct patterns of these marks may operate together to form a ’histone code’ that, in turn, precedes and influences gene activities within the chromatin, according to studies published last year by C. David Allis, Byrd Professor of Biochemistry and Molecular Genetics at U.Va., who is co-author of the new study.
The four major types of histones each have a long "tail" which "wags" outside the surface of the chromatin fiber. Last year’s studies examined lysines at the fourth (K4) and ninth (K9) positions on the tail of one of the histones, H3, and revealed that when a chemical methyl group is added to these two positions, it turns genes on or off, acting much like a master control switch according to a histone code.
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy
22.09.2017 | Physics and Astronomy