Molecular & Cell Biology

Category: Molecular & Cell Biology

Leaky intestines may cripple bacteria-fighting immune cells in patients with a rare hereditary disease, according to a study by researchers in Lausanne, Switzerland. The study, published in The Journal of Experimental Medicine on September 15, may explain why these patients suffer from recurrent bacterial infections.

Researchers at Johns Hopkins have identified a highly sensitive means of analyzing very tiny amounts of DNA. The discovery, they say, could increase the ability of forensic scientists to match genetic material in some criminal investigations. It could also prevent the need for a painful, invasive test given to transplant patients at risk of rejecting their donor organs and replace it with a blood test that reveals traces of donor DNA.

Neuroscientists have found that a gene mutation that arose more than half a million years ago may be key to humans' unique ability to produce and understand speech.

University at Buffalo researchers and colleagues studying a rare, blistering disease have discovered new details of how autoantibodies destroy healthy cells in skin. This information provides new insights into autoimmune mechanisms in general and could help develop and screen treatments for patients suffering from all autoimmune diseases, estimated to affect 5-10 percent of the U.S. population.

As we and other vertebrates age, our DNA accumulates mutations and becomes rearranged, which may result in a variety of age-related illnesses, including cancers. Biologists Vera Gorbunova and Andrei Seluanov have now discovered one reason for the increasing DNA damage: the primary repair process begins to fail with increasing age and is replaced by one that is less accurate.

The information encoded in our genes is translated into proteins, which ultimately mediate biological functions in an organism. Messenger RNA (mRNA) plays an important role, as it is the molecular template used for translation. Scientists from the Helmholtz Zentrum Muenchen and the Technische Universität Muenchen, in collaboration with international colleagues, have now unraveled a molecular mechanism of mRNA recognition, which is essential for understanding differential gene regulation in male and female organisms. The results are published in the renowned scientific journal Nature.

All human cells contain essentially the same DNA sequence – their genetic information. How is it possible that shapes and functions of cells in the different parts of the body are so different? While every cell's DNA contains the same construction master plan, an additional regulatory layer exists that determines which of the many possible DNA programs are active. This mechanism involves modifications of genome-bound histone proteins or the DNA itself with small chemical groups (e.g. methylation). It acts on top of the genetic information and is thus called 'epi'-genetic from the corresponding Greek word that means 'above' or 'attached to'.

This image depicts a tumor with reduced levels of enzyme UBC13 (top) and a control tumor (bottom) that has spread to the lungs.
Researchers at the University of California, San Diego School of Medicine have identified an enzyme that controls the spread of breast cancer. The findings, reported in the current issue of PNAS, offer hope for the leading cause of breast cancer mortality worldwide. An estimated 40,000 women in America will die of breast cancer in 2014, according to the American Cancer Society.

About 50 years ago, electron microscopy revealed the presence of tiny blob-like structures that form inside cells, move around and disappear. But scientists still don't know what they do — even though these shifting cloud-like collections of proteins are believed to be crucial to the life of a cell, and therefore could offer a new approach to disease treatment.

When we learn, we associate a sensory experience either with other stimuli or with a certain type of behaviour. The neurons in the cerebral cortex that transmit the information modify the synaptic connections that they have with the other neurons. According to a generally-accepted model of synaptic plasticity, a neuron that communicates with others of the same kind emits an electrical impulse as well as activating its synapses transiently. This electrical pulse, combined with the signal received from other neurons, acts to stimulate the synapses. How is it that some neurons are caught up in the communication interplay even when they are barely connected? This is the crucial chicken-or-egg puzzle of synaptic plasticity that a team led by Anthony Holtmaat, professor in the Department of Basic Neurosciences in the Faculty of Medicine at UNIGE, is aiming to solve. The results of their research into memory in silent neurons can be found in the latest edition of Nature.

The soil bacteria Streptomyces form filamentous branches that extend into the air to create spiraling towers of spores.
Scientists have identified the developmental on-off switch for Streptomyces, a group of soil microbes that produce more than two-thirds of the world's naturally derived antibiotic medicines.

A peptide responsible for cell communication in the brain, Vip (green) is reduced in the brains of mice that have little or no Lhx1 (right).
Scientists at the Salk Institute for Biological Studies have identified a gene that regulates sleep and wake rhythms.

With a featured publication in the Aug. 7 issue of Science, Montana State University researchers have made a significant contribution to the understanding of a new field of DNA research, with the acronym CRISPR, that holds enormous promise for fighting infectious diseases and genetic disorders.

This is a black truffle.
Black truffles, also known as Périgord truffles, grow in symbiosis with the roots of oak and hazelnut trees. In the world of haute cuisine, they are expensive and highly prized.

Researchers at the BBSRC-funded Babraham Institute, in collaboration with the Wellcome Trust Sanger Institute Single Cell Genomics Centre, have developed a powerful new single-cell technique to help investigate how the environment affects our development and the traits we inherit from our parents. The technique can be used to map all of the 'epigenetic marks' on the DNA within a single cell. This single-cell approach will boost understanding of embryonic development, could enhance clinical applications like cancer therapy and fertility treatments, and has the potential to reduce the number of mice currently needed for this research.

An international team of researchers, including scientists from the Max Planck Institute for Medical Research in Heidelberg, has just a reported a major step in understanding photosynthesis, the process by which the Earth first gained and now maintains the oxygen in its atmosphere and which is therefore crucial for all higher forms of life on earth.

In this image, the cells are stained red for cell protrusion, yellow for cell membrane and blue for nucleus.
Insights into how cells move through the body could lead to innovative techniques to stop cancer cells from spreading and causing secondary tumours, according to new UCL research.

This gif of membrane-anchored Ras (red) and individual SOS molecules (green) shows individual SOS molecules corralled into nanofabricated patches where all the membrane-associated Ras molecules they activate can be trapped.
A breakthrough discovery into how living cells process and respond to chemical information could help advance the development of treatments for a large number of cancers and other cellular disorders that have been resistant to therapy. An international collaboration of researchers, led by scientists with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley, have unlocked the secret behind the activation of the Ras family of proteins, one of the most important components of cellular signaling networks in biology and major drivers of cancers that are among the most difficult to treat.

One of the knots grows in size, while the other diffuses along the contour of the former.
Physicists of Johannes Gutenberg University Mainz (JGU) and the Graduate School of Excellence "Materials Science in Mainz" (MAINZ) have been able with the aid of computer simulations to confirm and explain a mechanism by which two knots on a DNA strand can interchange their positions. For this, one of the knots grows in size while the other diffuses along the contour of the former. Since there is only a small free energy barrier to swap, a significant number of crossing events have been observed in molecular dynamics simulations, i.e., there is a high probability of such interchange of positions.

This is a cross section of an injury in the large intestine with the intestinal epithelium shown in red.
Over 3.5 million people in Europe and the US suffer from Crohn's disease or ulcerative colitis – the two most common forms of IBD. Chronic bowel inflammation is caused by an overreaction of the immune system to the bacteria which naturally occur in the gut. "This overreaction can come about if, for example, the anti-stress mechanism in the cells of the intestinal mucosa does not function correctly," explains Prof. Dirk Haller of the TUM Chair of Nutrition and Immunology.

The molecular building blocks that make up DNA absorb ultraviolet light so strongly that sunlight should deactivate them – yet it does not. Now scientists have made detailed observations of a "relaxation response" that protects these molecules, and the genetic information they encode, from UV damage. The experiment at the Department of Energy's SLAC National Accelerator Laboratory focused on thymine, one of four DNA building blocks. Researchers hit thymine with a short pulse of ultraviolet light and used a powerful X-ray laser to watch the molecule's response: A single chemical bond stretched and snapped back into place within 200 quadrillionths of a second, setting off a wave of vibrations that harmlessly dissipated the destructive UV energy.

Case Western Reserve School of Medicine scientists have made an extraordinary double discovery. First, they have identified thousands of novel long non-coding ribonucleic acid (lncRNA) transcripts. Second, they have learned that some of them defy conventional wisdom regarding lncRNA transcripts, because they actually do direct the synthesis of proteins in cells.

Sperm (blue) latch onto a control egg (left) but can't bind to an egg lacking the glycoprotein ZP2 (right).
Before it can fertilize an egg, a sperm has to bind to and bore through an outer egg layer known as the zona pellucida. Despite decades of research, some of the biological mechanisms behind this process remain unclear. A study in The Journal of Cell Biology now identifies the protein in the zona pellucida that sperm latch onto.

DNA methylation has been identified as a potential biomarker of response to etanercept and adalimumab in patients with rheumatoid arthritis (RA) according to preliminary results from one of the largest methylome-wide investigations of treatment response to anti-TNF therapies.1 These data, presented today at the European League Against Rheumatism Annual Congress (EULAR 2014), bring clinicians a step closer to being able to personalise a patient's treatment pathway.

By cataloging over 18,000 proteins, researchers from TUM have produced an almost complete inventory of the human proteome. This information is now freely available in the ProteomicsDB database, which is a joint development of TUM and software company SAP. The database includes information for example on the types, distribution, and abundance of proteins in various cells and tissues as well as in body fluids.

This shows crosslink-inducing agents used in chemotherapy.
Environmental influences such as ionizing radiation, intense heat or various chemical substances damage the DNA constantly. Only thanks to efficient repair systems can mutations – changes in the DNA – largely be prevented. DNA crosslinks that covalently link both strands of the DNA double helix are among the most dangerous DNA lesions. Crosslinks block DNA replication and can thus cause cell death. Moreover, their faulty repair can trigger the development of tumors. Crosslink repair is highly complex and only vaguely understood today. A team of cancer researchers headed by Alessandro Sartori from the University of Zurich now reveals interesting details as to how cells recognize crosslink damage. In their study recently published in Cell Reports, the scientists demonstrate that the interplay between two specific proteins is crucial for the flawless repair of crosslink damage.

An international team of scientists has made a major step forward in our understanding of how enzymes 'edit' genes, paving the way for correcting genetic diseases in patients.

Stimulation of a certain population of neurons within the brain can alter the learning process, according to a team of neuroscientists and neurosurgeons at the University of Pennsylvania. A report in the Journal of Neuroscience describes for the first time that human learning can be modified by stimulation of dopamine-containing neurons in a deep brain structure known as the substantia nigra. Researchers suggest that the stimulation may have altered learning by biasing individuals to repeat physical actions that resulted in reward.

This image shows a GroEL/ES nano-cage (light blue and white) with encapsulated substrate protein (orange).
Proteins are the workhorses of the cell and thus responsible for almost all biological functions including metabolism, signal transmission or the determination of the cell's shape. However, before they can fulfill their various tasks, the chain-like molecules must first adopt an intricate three-dimensional conformation. This process is called protein folding and is one of the most important processes in biology. In fact, in the event of improper folding, proteins are often no more able to carry out their duties, or even tend to clump together in aggregates. This in turn can lead to severe diseases like Alzheimer's or Parkinson's. In order to avoid this, specialized proteins, the so-called chaperones, help other proteins to adopt their proper shape.

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