Molecular & Cell Biology

Category: Molecular & Cell Biology

Fluorescently labeled microtubules extend from the tips of the dendrites (top) into the axon and down into the giant synaptic terminal (bottom) of a single isolated goldfish retinal bipolar cell. A loop of microtubules encircles the inner plasma membrane of the terminal and anchors mitochondria.
Researchers have discovered a thick band of microtubules in certain neurons in the retina that they believe acts as a transport road for mitochondria that help provide energy required for visual processing. The findings appear in the July issue of The Journal of General Physiology.

Rodolfo Llinás of New York University School of Medicine at the MBL, Woods Hole, where he spends each summer as a Whitman Center iInvestigator.
Sleep seems simple enough, a state of rest and restoration that almost every vertebrate creature must enter regularly in order to survive. But the brain responds differently to stimuli when asleep than when awake, and it is not clear what brain changes happen during sleep. "It is the same brain, same neurons and similar requirements for oxygen and so on, so what is the difference between these two states?" asks Rodolfo Llinás, a professor of neuroscience at New York University School of Medicine and a Whitman Center Investigator at the Marine Biological Laboratory (MBL) in Woods Hole. In a recent paper, Choi, Yu, Lee, and Llinás announced that a specific calcium channel plays a crucial role in healthy sleep, a key step toward understanding both normal and abnormal waking brain functions.

The flu virus can be lethal. But what is often just as dangerous is the body's own reaction to the invader. This immune response consists of an inflammatory attack, meant to kill the virus. But if it gets too aggressive, this counterattack can end up harming the body's own tissues, causing damage that can lead to death.

Stanford University researchers studying how the brain controls movement in people with paralysis, related to their diagnosis of Lou Gehrig's disease, have found that groups of neurons work together, firing in complex rhythms to signal muscles about when and where to move.

Researchers at the University of Toronto have uncovered how Gram-negative bacteria -- a broad class of bugs that cause diseases ranging from gonorrhea to diarrhea and pneumonia -- can trigger a reaction from our immune system. This discovery could lead to new therapies and treatments that use the immune system to fight infections instead of antibiotics.

This is a Darling Downs funnel-web spider. Its venom evolved from an insulin-like hormone.
Funnel-web spider venom contains powerful neurotoxins that instantly paralyze prey (usually insects). Millions of years ago, however, this potent poison was just a hormone that helped ancestors of these spiders regulate sugar metabolism, similar to the role of insulin in humans. Surprisingly, this hormone's weaponization--described on June 11 in the journal Structure--occurred in arachnids as well as centipedes, but in different ways.

Period-lengthening/-shortening molecules can change the biological clock rhythm.
A team of chemists and biologists at the Institute of Transformative Bio-Molecules (ITbM), Nagoya University have succeeded in finding new molecules that change the circadian rhythm in mammals by applying synthetic chemistry methods, which makes use of highly selective metal catalysts.

Fluorescence microscopy of maternal and paternal chromosomes is shown at the first mitosis during the oocyte to embryo transition in the mouse.
Researchers in the University of Georgia's Regenerative Bioscience Center are visually capturing the first process of chromosome alignment and separation at the beginning of mouse development. The findings could lead to answers to questions concerning the mechanisms leading to birth defects and chromosome instability in cancer cells.

The enzyme that degrades messenger RNA follows the ribosomes and stops every 3 nucleotides.
Once messenger RNA (mRNA) has done its job - conveying the information to produce the proteins necessary for a cell to function - it is no longer required and is degraded. Scientists have long thought that the decay started after translation was complete and that decaying RNA molecules provided little biological information.

The process that allows our brains to learn and generate new memories also leads to degeneration as we age, according to a new study by researchers at MIT.

Senescence, a phenomenon in which cells cease to divide and grow, can be caused by everything from natural DNA damage to treatment with chemotherapy. However, several mechanisms allow for cells to bypass senescence and grow out of control, eventually becoming cancerous. Now, scientists at The Wistar Institute have identified how a specific variant of a key protein complex found in human cells called condensin can reorganize a cell's genetic architecture in such a way as to promote senescence, making it an important facilitator in a cell's anticancer ability.

Surveys of the genomic terrain of cancer have turned up a curious phenomenon in some tumor cells: a massive rearrangement of DNA in one or a few chromosomes, thought to be produced during a single cell cycle. In a new study, scientists at Dana-Farber Cancer Institute demonstrate how this sudden, isolated shuffling of genetic material - known as chromothripsis - can occur.

Axons in red and neuronal cell bodies in green show cell bodies following the red axons
When nerve cells form in an embryo they do not start off in the right place but have to be guided to their final position by navigating a kind of molecular and cellular "map" in order to function properly. In a recent research study published in Nature Communications neurobiologist Sara Wilson, Umeå University, found that during embryonic development different parts of the nerve cell are important for guiding other nerve cells into their physical positions.

Using nature for inspiration, a team of Northwestern University scientists is the first to develop an entirely artificial molecular pump, in which molecules pump other molecules. This tiny machine is no small feat. The pump one day might be used to power other molecular machines, such as artificial muscles.

A molecular switch that seems to be essential for embryonic heart cells to grow into more mature, adult-like heart cells has been discovered.

GTEx findings reveal new insights into how DNA differences influence gene activity, disease susceptibility.
Researchers funded by the National Institutes of Health Genotype-Tissue Expression (GTEx) project have created a new and much-anticipated data resource to help establish how differences in an individual's genomic make-up can affect gene activity and contribute to disease. The new resource will enable scientists to examine the underlying genomics of many different human tissues and cells at the same time, and promises to open new avenues to the study and understanding of human biology.

For years, scientists have been puzzled by the presence of short stretches of genetic material floating inside a variety of cells, ranging from bacteria to mammals, including humans. These fragments are pieces of the genetic instructions cells use to make proteins, but are too short a length to serve their usual purpose. Reporting in this week's Cell, researchers at Rockefeller have discovered a major clue to the role these fragments play in the body -- and in the process, may have opened up a new frontier in the fight against breast cancer.

New research from the University of Eastern Finland and Kuopio University Hospital can help explain the prevalence of widespread syndromes such as carpal tunnel syndrome and sciatica. According to the results, neural movements can be measured by using non-invasive techniques, which are also applicable in diagnostics and rehabilitation planning.

Using proteomics techniques to study injured optic nerves, researchers at Boston Children's Hospital have identified previously unrecognized proteins and pathways involved in nerve regeneration. Adding back one of these proteins--the oncogene c-myc--they achieved unprecedented optic nerve regeneration in mice when combined with two other known strategies. The findings were published online April 30 by the journal Neuron.

Top: Exemplary neuron reconstructions for each of the 10 major cell types of the vibrissal part of rat sensory cortex (dendrites, the part of a neuron that receives information from...
Researchers at the Max Planck Institute for Biological Cybernetics (Germany), VU University Amsterdam (Netherlands) and Max Planck Florida Institute for Neuroscience (USA) succeed in reconstructing the neuronal networks that interconnect the elementary units of sensory cortex - cortical columns.

Remnants of viruses, called retrotransposons, jumped around more frequently within the genomes of cells lacking the histone variant H3.3.
A family of proteins known as histones provides support and structure to DNA, but for years, scientists have been puzzling over occasional outliers among these histones, which appear to exist for specific, but often mysterious reasons. Now, researchers have uncovered a new purpose for one such histone variant: preventing genetic mutations by keeping certain so-called "jumping genes" in place.

A biochemist from The University of Texas Health Science Center at San Antonio is a co-author on a paper in Nature that describes a new, more efficient method of making ribonucleic acids (RNAs).

Collision of the DNA replication machinery with lesions in the DNA triggers the recruitment of a large number of DNA repair factors (yellow) that help to repair the lesions.
During each cell division, more than 3.3 billion base pairs of genomic DNA have to be duplicated and segregated accurately to daughter cells. But what happens when the DNA template is damaged in such a way that the replication machinery gets stuck? To answer this question, scientists in the team of Matthias Mann at the Max Planck Institute (MPI) of Biochemistry in Martinsried near Munich, with colleagues in Copenhagen and at Harvard, have analyzed how the protein composition of the DNA replication machinery changes upon encountering damaged DNA.

Rice University researchers Peter Wolynes, left, and Bin Zhang are working to formulate an energy-landscape theory for chromosomes. The theory could help scientists understand the genomic roots of gene regulation,...
Human chromosomes are much bigger and more complex than proteins, but like proteins, they appear to fold and unfold in an orderly process as they carry out their functions in cells.

This is a microscope image of polytene chromosomes from Drosophila melanogaster, in which, using staining techniques, scientists have visualized the protein dDsk2, a molecule never previously associated with chromatin
Until today, the proteins known as ubiquitin receptors have been associated mainly with protein degradation, a basic cell cleaning process. A new function now described for the protein dDsk2 by the team headed by Ferran Azorín, group leader at the Institute for Research in Biomedicine (IRB Barcelona) and CSIC research professor, links ubiquitin receptors for the first time with the regulation of gene expression. This discovery, published today in Nature Communications, opens up a double scenario, one focused on basic epigenomic research and the other biomedical, because of the link between dDsk2 and neurodegenerative diseases.

Researchers have developed a large-scale sequencing technique called Genome and Transcriptome Sequencing (G&T-seq) that reveals, simultaneously, the unique genome sequence of a single cell and the activity of genes within that single cell.

This is an artist's illustration of an X-chromosome.
Researchers at Caltech have discovered how an abundant class of RNA genes, called long non-coding RNAs (lncRNAs, pronounced link RNAs) can regulate key genes. By studying an important lncRNA, called Xist, the scientists identified how this RNA gathers a group of proteins and ultimately prevents women from having an extra functional X-chromosome--a condition in female embryos that leads to death in early development. These findings mark the first time that researchers have uncovered the detailed mechanism of action for lncRNA genes.

These are images of mouse neurons from the hippocampal region of the brain. Levels of the surface receptor GluR1, orange, are shown in unmodified neurons, left, and in those with...
Johns Hopkins scientists have discovered that neurons are risk takers: They use minor "DNA surgeries" to toggle their activity levels all day, every day. Since these activity levels are important in learning, memory and brain disorders, the researchers think their finding will shed light on a range of important questions. A summary of the study will be published online in the journal Nature Neuroscience on April 27.

New research from the Monell Center reveals that tumor necrosis factor (TNF), an immune system regulatory protein that promotes inflammation, also helps regulate sensitivity to bitter taste. The finding may provide a mechanism to explain the taste system abnormalities and decreased food intake that can be associated with infections, autoimmune disorders, and chronic inflammatory diseases.

Genes usually always be expressed as in Western writing: from left to right on the white canvas of our DNA. So when we speak of the activity of our genome, in fact we are referring to the expression of genes in this sense of the double-stranded DNA.

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