Bioengineers Devise ‘Dimmer Swith’ To Regulate Gene Expression In Mammal Cells

Three Boston University biomedical engineers have created a genetic dimmer switch that can be used to turn on, shut off, or partially activate a gene’s function. Professor James Collins, Professor Charles Cantor and doctoral candidate Tara Deans invented the switch, which can be tuned to produce large or small quantities of protein, or none at all

This switch helps advance the field of synthetic biology, which rests on the premise that complex biological systems can be built by arranging components or standard parts, as an electrician would to build an electric light switch. Much work in the field to date uses bacteria or yeast, but the Boston University team used more complex mammalian cells, from hamsters and mice. The switch has several new design features that extend possible applications into areas from basic research to gene therapy.

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Scientists find key to stem cell immortality

One of the medical marvels of stem cells is that they continue to divide and renew themselves when other cells would quit. But what is it that gives stem cells this kind of immortality. Researchers now report in the June 16, 2005 issue of the journal Nature that microRNAs — tiny snippets of genetic material that have now been linked to growth regulation in normal cells as well as cancer growth in abnormal cells — appear to shut off the “stop signals” or brakes that would normally tell cells to stop dividing.

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Virus Uses Tiny RNA To Evade The Immune System

In the latest version of the hide-and-seek game between pathogens and the hosts they infect, researchers have found that a virus appears to cloak itself with a recently discovered gene silencing device to evade detection and destruction by immune cells.

The report by Howard Hughes Medical Institute (HHMI) researchers in an article published in the June 2, 2005, issue of Nature may be the first to show how a virus uses the gene silencing machinery for its own infectious purposes.

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Mechanism of microRNAs deciphered

Over 30% of our genes are under the control of small molecules called microRNAs. They prevent specific genes from being turned into protein and regulate many crucial processes like cell division and development, but how they do so has remained unclear. Now researchers from the European Molecular Biology Laboratory (EMBL) have developed a new method that uncovered the mode of action of microRNAs in a test tube. The study, which is published in the current online issue of Nature, reveals that microRNAs block the initiation of translation, the earliest step in the process that turns genetic information stored on messenger RNAs into proteins.
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Carbon Nanotubes versus HIV

Researchers at Stanford University have added one more trick to carbon nanotubes’ repertoire of accomplishments: a way to fight the human immunodeficiency virus (HIV). Chemistry professor Hongjie Dai and his colleagues have used carbon nanotubes to transport RNA into human white blood cells that defend the body from disease, making the cells less susceptible to HIV attack.

In a paper now online in the journal Angewandte Chemie, Dai and his colleagues describe attaching RNA to carbon nanotubes, which enter T cells and deliver the RNA. When the researchers placed T cells in a solution of the carbon nanotube-RNA complex, receptor proteins on the cell surfaces went down by 80 percent. Carbon nanotubes are known to enter many different types of human cells, although researchers don’t understand exactly how they do it. Some experts suspect that because of their long, thin shape, nanotubes enter cells much as a needle passes through skin.

Read rest of the story on Technology Review site

Regulating the nuclear architecture of the cell

An organelle called the nucleolus resides deep within the cell nucleus and performs one of the cell’s most critical functions: it manufactures ribosomes, the molecular machines that convert the genetic information carried by messenger RNA into proteins that do the work of life.

Gary Karpen and Jamy Peng, researchers in the Life Sciences Division of the Department of Energy’s Lawrence Berkeley National Laboratory, have now discovered two pathways that regulate the organization of the nucleolus and other features of nuclear architecture, maintaining genome stability in the fruit fly Drosophila melanogaster.
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Reprogramming Biology

Visionary futurist Ray Kurzweil, whose remarkable ideas on technological progress have been an inspiration for Biosingularity blogs, have a wonderful concise article on biological advances in recent issue of Scientific American

As a scientist working on biological systems I fully agree and whole heartedly support Kurzweil's observations that: " Biology is now in the early stages of an historic transition to an information science, while also gaining the tools to reprogram the ancient information systems of life ….. We are now beginning to understand biology as a set of information processes, and we're developing realistic models and simulations of how the processes involved in disease and aging progress. Moreover, we are developing the tools to reprogram them."

In the article Kurzweil predicts that tinkering with our genetic programs will extend human lifespan beyond the current limits. He also reiterates that biological systems are also subject to the "law of accelerating returns", which had tremendous impact on information technologies. Indeed, the cost of sequencing and synthesizing gene base pairs have decreased more than 10,000 fold over the last 15 years, and this exponential progress is currently accelerating as predicted by Kurzweil in his recent book. 

Read rest of the article at Scientific American web site.