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A “Jumping Gene’s” Preferred Targets May Influence Genome Evolution

By Guest PostSeptember 10, 2011Scienceallan spradling, baylor college of medicine, cell, chromosomes, DNA, dna duplication, drosophila, drosophila melanogaster, drosophila transposons, fruit fly, gene disruption project, gene function, genetic blueprint, genome duplication cycle, genome structure, hugo bellen, human cell, human genome, jumping genes, minos, model organisms, p element, piggybac, rogerhoskins, transposons

Baltimore, MD — The human genome shares several peculiarities with the DNA of just about every other plant and animal. Our genetic blueprint contains numerous entities known as transposons, or “jumping genes,” which have the ability to move from place to place on the chromosomes within a cell.

An astounding 50% of human DNA comprises both active transposon elements and the decaying remains of former transposons that were active thousands to millions of years ago before becoming damaged and immobile. If all of this mobile and formerly mobile DNA were not mysterious enough, every time a plant, animal or human cell prepares to divide, the chromosome regions richest in transposon-derived sequences, even elements long deceased, are among the last to duplicate. The reason for their delayed duplication, if there is one, has eluded biologists for more than 50 years. (more…)

Research Suggests HIV Causes Rapid Aging in Key Infection-fighting Cells

By Guest PostJanuary 29, 20111 commentHealthaids epidemic, antiretroviral therapy, beth d jamieson, cancers, cd31 t cells, cd4+ helper t cells, cd4+ t cell numbers, chromosomes, clinical conditions, disease, hiv 1 infected adults, hiv seronegative, hiv-positive, illnesses, immune systems, infect, infection, liver diseases, natural cell division, pathogens, t cells, tammy m rickabaugh, telomeres, virtual death, virus

In the early years of the AIDS epidemic, being infected with the virus that causes the disease was considered a virtual death sentence. But with the development of antiretroviral therapy, many with HIV are now living much longer. In fact, it is estimated that by 2015, about half of all HIV-positive individuals will be older than 50.

Yet those over 50 also progress to AIDS faster than adults in their 20s or 30s. And those in the younger age bracket — even those responding well to antiretroviral therapy — still exhibit illnesses and clinical conditions commonly associated with older people, such as certain cancers and liver diseases. For the most part, the reasons for this have remained a mystery. (more…)

U-M Researchers Identify Protein Essential for Cell Division in Blood-forming Stem Cells

By Guest PostDecember 3, 2010Scienceampk, blood-forming stem cells, cell death, cell therapies, cellular metabolism, chromosomes, daisuke nakada, daughter cells, degenerative diseases, energy production, lkb1, normal cell division, protein, protein kinase, sean morrison, stem cell biology, stem cell function, stem cells, thomas saunders, tumor suppressor

ANN ARBOR, Mich.— University of Michigan researchers have discovered that a protein known to regulate cellular metabolism is also necessary for normal cell division in blood-forming stem cells. Loss of the protein results in an abnormal number of chromosomes and a high rate of cell death.

The finding demonstrates that stem cells are metabolically different from other blood-forming cells, which can divide without the protein, Lkb1. This metabolic difference could someday be used to better control the behavior of blood-forming stem cells used in disease treatments, said Sean Morrison, director of the U-M Center for Stem Cell Biology, which is based at the Life Sciences Institute. (more…)

Getting a Tighter Grip on Cell Division

By Guest PostNovember 25, 2010Sciencebungo akiyoshi, cell, cell division, chinese handcuff, chromosomes, DNA, genetic information, kinetochore, microtubule, sue biggins

*Molecular “machine” responsible for pulling chromosome copies apart is isolated and seen in action outside the cell*

The dance of cell division is carefully choreographed and has little room for error. Paired genetic information is lined up in the middle of the cell in the form of chromosomes. The chromosomes must then be carefully pulled apart so that the resulting daughter cells each have an identical copy of the mother cell’s DNA. (more…)

New 3-D Model of RNA ‘Core Domain’ of Enzyme Telomerase May Offer Clues to Cancer, Aging

By Guest PostNovember 6, 2010Health, Scienceaging, cancer, cells, chromosomes, DNA, dna damage, enzyme, helical extension, juli feigon, medicine, nmr, nobel prize, nuclear magnetic resonance, physiology, proteins, pseudoknot, qi zhang, rna, spectroscopy, telomerase, telomeres, virus

A model representation of telomerase's RNA "core domain," determined by Juli Feigon, Qi Zhang and colleagues in Feigon's UCLA laboratory. Image credit: Juli Feigon, UCLA Chemistry and Biochemistry/PNAS

Telomerase is an enzyme that maintains the DNA at the ends of our chromosomes, known as telomeres. In the absence of telomerase activity, every time our cells divide, our telomeres get shorter. This is part of the natural aging process, as most cells in the human body do not have much active telomerase. Eventually, these DNA-containing telomeres, which act as protective caps at the ends of chromosomes, become so short that the cells die.

But in some cells, such as cancer cells, telomerase, which is composed of RNA and proteins, is highly active and adds telomere DNA, preventing telomere shortening and extending the life of the cell.

UCLA biochemists have now produced a three-dimensional structural model of the RNA “core domain” of the telomerase enzyme. Because telomerase plays a surprisingly important role in cancer and aging, understanding its structure could lead to new approaches for treating disease, the researchers say. (more…)

Tag Archives: chromosomes

A “Jumping Gene’s” Preferred Targets May Influence Genome Evolution

Research Suggests HIV Causes Rapid Aging in Key Infection-fighting Cells

U-M Researchers Identify Protein Essential for Cell Division in Blood-forming Stem Cells

Getting a Tighter Grip on Cell Division

New 3-D Model of RNA ‘Core Domain’ of Enzyme Telomerase May Offer Clues to Cancer, Aging