What Holds Chromosomes Together - Max Planck Researchers Elucidate the Structure of DNA-Packaging Proteins

SMC-Kleisin-Complex. (Credit: Image courtesy of Max Planck Institute of Biochemistry) In each cell about two meters of DNA must fit into a cell nucleus that has a diameter of only a few thousandths of a millimeter. There the DNA is organized in individual chromosomes in the form of very long filaments. If they are not equally and accurately distributed to the daughter cells during cell division, this can result in cancer or genetic defects such as trisomy 21. Therefore, to ensure safe transport of DNA during cell division the long and coiled DNA fibers must be tightly packed. Scientists have only a sketchy understanding of this step. The SMC-kleisin protein complexes play a key role in this process. They consist of two arms (SMC) and a bridge (kleisin). The arms wrap around the DNA like a ring and thus can connect duplicated chromosomes or two distant parts of the same chromosome...

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New Look at Cell Membrane Reveals Surprising Organization

Researchers found that a class of molecules called sphingolipds congregate in large patches in the cell membrane. Red and yellow colors indicate local elevations in the sphingolipid abundance. Using a completely new approach to imaging cell membranes, a study by researchers from the University of Illinois, Lawrence Livermore National Laboratory and the National Institutes of Health revealed some surprising relationships among molecules within cell membranes. Led by Mary Kraft, a U. of I. professor of chemical and biomolecular engineering, the team published its findings in the Proceedings of the National Academy of Sciences. Cells are enveloped in semi-permeable membranes that act as a barrier between the inside and outside of the cell. The membrane is mainly composed of a class of molecules called lipids, studded with proteins that help regulate how the cell responds to...

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The cell that isn’t:New technique captures division of membrane-less cells

This may look like yet another video of a dividing cell, but there’s a catch. You are looking at chromosomes (red) being pulled apart by the mitotic spindle (green), but it’s not a cell, because there’s no cell membrane. Like a child sucking an egg out of its shell, Ivo Telley from the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, removed these cellular ‘innards’ from a fruit fly embryo, at a stage when it is essentially a sac full of membrane-less ‘cells’ that divide and divide without building physical barriers to separate themselves from each other. “It’s the first time we can study ongoing cell division without the cell membrane, and that means we can physically manipulate things,” says Telley, “so we can uncover the physical forces involved, and see what are the constraints.” The new technique is described in detail today in Nature Protocols, and has already led Telley and colleagues to a surprising discovery. They found that, although successive divisions fill the embryo with more and more material, leaving less and less space for each spindle, and spindles become smaller as the embryo develops, simply squeezing the ‘cell’ into tighter quarters doesn’t make it produce a smaller spindle. Combined with the genetic manipulation approaches commonly used in fruit fly studies, the scientists believe their new technique will help to unravel this and other mysteries of how a cell becomes two. In a nutshell: New technique allows scientists to study cell division without cell membrane Advantages: can physically constrain and manipulate; can access nuclei normally buried deep...

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Protein Folding via Charge Zippers

Membrane proteins are the “molecular machines” in biological cell envelopes. They control diverse processes, such as the transport of molecules across the lipid membrane, signal transduction, and photosynthesis. Their shape, i.e. folding of the molecules, plays a decisive role in the formation of, e.g., pores in the cell membrane. In the Cell magazine, researchers of Karlsruhe Institute of Technology and the University of Cagliari are now reporting a novel charge zipper principle used by proteins to form functional units (DOI: 10.1016/j.cell.2012.12.017) Like the teeth of a zipper, the charged amino acids (red, blue) form connections between protein segments. In this way, they can form pores in the cell membrane. (Figure: KIT) “It is fascinating to see the elegant basic principles that are used by nature to construct molecular assemblies,” explains Anne Ulrich, Director...

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IMP Scientists shed light on the “dark matter” of DNA

In each cell, thousands of regulatory regions control which genes are active at any time. Scientists at the Research Institute of Molecular Pathology (IMP) in Vienna have developed a method that reliably detects these regions and measures their activity. The new technology is published online by Science this week. Fluorescence image of ovarian tissue of the fruit fly. DNA is stained in blue, the activity of enhancers is represented by the green colour. Copyright: IMP Genome sequences store the information about an organism’s development in the DNA’s four-letter alphabet. Genes carry the instruction for proteins, which are the building blocks of our bodies. However, genes make up only a minority of the entire genome sequence – roughly two percent in humans. The remainder was once dismissed as “junk”, mostly because its function remained elusive. “Dark matter” might be more...

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Molecular twist helps regulate the cellular message to make histone proteins

 Histone proteins are the proteins that package DNA into chromosomes.  Every time the cell replicates its DNA it must make large amounts of newly made histones to organize DNA within the nucleus. An imbalance in the production of DNA and histones is usually lethal for the cell, which is why the levels of the messenger RNA (mRNA) encoding the histone proteins must be tightly controlled to ensure the proper amounts of histones (not too many and not too few) are made. In a collaborative effort published online in the January 18, 2013 issue of the journal Science, researchers at the University of North Carolina and Columbia University show for the first time how two key proteins in messenger RNA communicate via a molecular twist to help maintain the balance of histones to DNA. “This is one of the safeguards that our cells have evolved and it is part of the normal progression...

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Study Quantifies the Size of Holes Antibacterials Create in Cell Walls to Kill Bacteria

The rise of antibiotic-resistant bacteria has initiated a quest for alternatives to conventional antibiotics. One potential alternative is PlyC, a potent enzyme that kills the bacteria that causes strep throat and streptococcal toxic shock syndrome. PlyC operates by locking onto the surface of a bacteria cell and chewing a hole in the cell wall large enough for the bacteria’s inner membrane to protrude from the cell, ultimately causing the cell to burst and die. Research has shown that alternative antimicrobials such as PlyC can effectively kill bacteria. However, fundamental questions remain about how bacteria respond to the holes that these therapeutics make in their cell wall and what size holes bacteria can withstand before breaking apart. Answering those questions could improve the effectiveness of current antibacterial drugs and initiate the development of new ones. Researchers ...

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Cheating — and getting away with it

We would all like to believe that there is a kind of karma in life that guarantees those who cheat eventually pay for their bad behavior, if not immediately, then somewhere down the line. But a study of a new gene in the amoeba Dictyostelium discoideum suggests that, at least for amoebae, it is possible to cheat and get away with it. The experimental work was conducted by then graduate student Lorenzo Santorelli as part of a collaboration between evolutionary biologists David C. Queller and Joan E. Strassmann of Rice University and Gadi Shaulsky and Adam Kuspa of Baylor College of Medicine. Santorelli has since moved to Oxford University and his advisors to Washington University in St. Louis, where Queller is the Spencer T. Olin Professor of Biology and Strassmann is a professor of biology, both in Arts & Sciences. The cheat in question is putting more than your clone’s...

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Virus caught in the act of infecting a cell

The detailed changes in the structure of a virus as it infects an E. coli bacterium have been observed for the first time, report researchers from The University of Texas at Austin and The University of Texas Health Science Center at Houston (UT Health) Medical School this week in Science Express. To infect a cell, a virus must be able to first find a suitable cell and then eject its genetic material into its host. This robot-like process has been observed in a virus called T7 and visualized by Ian Molineux, professor of biology at The University of Texas at Austin, and his colleagues. Researchers found that the T7 virus has six tail fibers that are folded back against its capsid.  The fibers extend as the virus locates  a suitable host and as it “walks”  across its host cell surface to find  a site to infect. The researchers show that when searching for...

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Team Zone A

Team Under Asif Raazaq, Co-Founder/Director Shruti Thakur, Regional Head Delhi NCR Stuti Mahajan, Regional Chief Editor Delhi NCR Avantika Rawat, College Head Delhi NCR (JIIT) Jahnavi Sharma, College Head Delhi NCR (JIIT) Deepali Gupta, Regional Head- Research and Development Delhi NCR Pawan Kushwaha, Regional Head-Tech and Operation U.P. Divyanshi Yadav, Regional Head Research and Development U.P. Ambuj Mishra, Regional Head External Relations, U.P. Abhishek Singh, Regional Head Media and Advertising, U.P. Wasi Syed, Regional Head Research and Development, Punjab Sanjana Vig, Volunteer Kalyani Verma, Volunteer ...

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Research opportunities at TIFR

Research Opportunities for exceptionally talented and strongly motivated students. The Tata Institute of Fundamental Research is India's premier institution for advanced research in fundamental sciences. The Institute runs a graduate programme leading to the award of Ph.D. degree, as well as M.Sc. and Integrated Ph.D. in certain subjects. With its distinguished faculty, world class facilities and stimulating research environment, it is an ideal place for aspiring scientists to initiate their career. The Graduate Programme at TIFR is classified into the following Subjects - Mathematics, Physics, Chemistry, Biology, Computer & Systems Sciences (including Communications and Math. Finance) and Science Education. It is conducted at the Mumbai campus and various National Centres of TIFR. Graduate School Admissions (GS-2013) Application Procedure Students can apply online.  Please follow appropriate link on this website for filling up the application form.  Read the instructions carefully before you start filling up the online application form. Manual Applications: Students from remote areas who do not have access to internet may apply manually.   They may send a request for application form (without DD) along with a self-addressed stamped (Rs 20/-) envelope (size 25cm x 17cm) superscribed "GS-2013 (Subject)" to : For Biology: Admissions Section, NCBS, Bangalore  . For other subjects, except Science Education: Universvity Cell , TIFR, Mumbai. The filled-in application form should be sent along with DD and two passport size photographs (one pasted on the application and one stapled to it). Students may appear for the written...

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Masters and Ph.D at IISc Bangalore

INFORMATION AT A GLANCE Indian Institute of Science (IISc) also referred to as ‘the Institute’ at certain places in this document announce Admissions to the following: Research programmes - Doctoral (Ph D) and Master’s (M Sc [Engg]) Course programmes - (ME/M Tech/M Des/M.Mgt) Integrated Ph D programmes Candidates should go through the requirement of basic qualifications carefully and satisfy themselves that they fulfill all the eligibility criteria.  1.    Candidates applying for : Research programmes may indicate preferences for a maximum of 3 departments / centers / units. Course programmes (ME /M Tech /M Des) may indicate preferences for a maximum of 5 disciplines. Course programme (M.Mgt) have only one option under Management Studies. Integrated Ph D programmes may indicate preferences for a maximum of 2 disciplines. Application Forms with incomplete / incorrect information are liable to be rejected. 2.    The print out of the online Application Form should reach the Assistant Registrar (Academic) Admissions Unit Indian Institute of Science Bangalore 560012 on or before March 15,  2012 for the Sponsored candidates and March 26,  2012 for others.  The last date prescribed for the receipt of Application Forms cannot be extended for any reason. 3.    Please note that the receipt of an Admit Card for the Entrance Test 2012 or call letter for interview does not confer any right upon the applicant for admission to the Institute.  4.    Please...

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Team Zone N

North Team under Nimish Gopal, Co-Founder/Director Tushar Kant, Chief Designer (Former) Abin Ghosh, Regional Head-Technology and Maintenance Mohd Tayyab, Regional Head-Editor Rajat Yadav, Regional Head-External Relations Naveen Nagar, Regional Head-Research and Development Harsh Patodia, Regional Head-Finance Teena Mehlawat, Regional Head-Rajasthan Tanvi Das, Editor-GBioFin Anurag Tiwari, Student Head-Haryana Designer team- Manohar, Arun, Saurabh, Akshay, Moinak,  Subhranshu ...

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In Epigenomics, Location is Everything

In a novel use of gene knockout technology, researchers at the University of California, San Diego School of Medicine tested the same gene inserted into 90 different locations in a yeast chromosome – and discovered that while the inserted gene never altered its surrounding chromatin landscape, differences in that immediate landscape measurably affected gene activity. The findings, published online in the Jan. 3 issue of Cell Reports, demonstrate that regulation of chromatin – the combination of DNA and proteins that comprise a cell’s nucleus – is not governed by a uniform “histone code” but by specific interactions between chromatin and genetic factors. An x-ray micrograph of a yeast cell, Saccharomyces cerevisiae, as it buds before dividing. Courtesy of Carolyn Larabell, UC San Francisco, Lawrence Berkeley National Laboratory and the National Institute of General Medical...

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Rare Form of Active 'Jumping Genes' Found In Mammals

Little brown bat (Myotis lucifugus) J.N. Stuart Much of the DNA that makes up our genomes can be traced back to strange rogue sequences known as transposable elements, or jumping genes, which are largely idle in mammals. But Johns Hopkins researchers report they have identified a new DNA sequence moving around in bats — the first member of its class found to be active in mammals. The discovery, described in a report published in December on the website of the Proceedings of the National Academy of Sciences, offers a new means of studying evolution, and may help in developing tools for gene therapy, the research team says.“Transposable elements are virtually everywhere in nature, from bacteria to humans,” says Nancy Craig, Ph.D., a Howard Hughes investigator and professor in the Johns Hopkins University School of Medicine’s Department of Molecular Biology and...

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