Closest Look Ever At Native Human Tissue

"This is a real breakthrough in two respects," says Achilleas Frangakis, group leader at EMBL. "Never before has it been possible to look in three dimensions at a tissue so close to its native state at such a high resolution. We can now see details at the scale of a few millionths of a millimetre. In this way we have gained a new view on the interactions of molecules that underlie cell adhesion in tissues -- a mechanism that has been disputed over decades."

So far, the only information available about a protein's position and interactions in a cell was based on either light microscopy images at poor resolution or techniques that remove proteins from their natural context. Frangakis and his group have been developing a technique called cryo-electron tomography, with which a cell or tissue is instantly frozen in its natural state and then examined with an electron micro-scope.

Electron microscopy normally requires tissue to be treated with chemicals or coated in metal, a procedure that disturbs the natural state of a sample. With cyro-electron tomography, images are taken of the untreated sample from different directions and assembled into an accurate 3D image by a computer.

The researchers applied this technique to observe proteins that are crucial for the integrity of tissues and organs like the skin and the heart, but also play an important role in cell proliferation. These proteins, called cadherins, are anchored in cell membranes and interact with each other to bring cells close together and interlink them tightly.

"We could see the interaction between two cadherins directly, and this revealed where the strength of human skin comes from," says Ashraf Al-Amoudi, who carried out the work in Frangakis' lab. "The trick is that each cadherin binds twice: once to a molecule from the juxtaposed cell, and once to its next-door neighbour. The system works a bit like specialised Velcro and establishes very tight contacts between cells."

The new insights into the cadherin system broadens the understanding of structural aspects of cell adhesion and shed light on other crucial processes such as cell proliferation. The technical advances achieved in cryo-electron tomography of frozen sections open up new possibilities to study more systems at native conditions with molecular resolution.

Adapted from materials provided by European Molecular Biology Laboratory

Global Climate Change: The Impact Of El Niño On Galápagos Marine Iguanas

According to the authors, recurring El Niño events provide an ideal system to study the impact of human-mediated climate change on ecosystems worldwide, by allowing observation of changes in populations associated with individual events.

"Since global warming is expected to cause an increase in the strength and frequency of El Niño events, it is important to evaluate the impact of El Niño on natural populations and their capacity to respond to environmental stresses," said Gisella Caccone, senior research scientist in ecology and evolutionary biology at Yale, and senior author of the paper published recently in the Public Library of Science One.

In this study, the researchers investigated the effect of sea surface warming associated with the single, intense El Niño event of 1997 to 1998 on genetic diversity in Galápagos marine iguana populations. They found that populations within the same species responded very differently.

Collaboration between German scientists who fortuitously collected and archived samples between 1991 and 1993 and Yale researchers who sampled the iguanas in 2004 enabled these unique before-and after comparisons. More than 800 samples from 11 Galápagos marine iguana populations were evaluated.

The researchers looked for changes in levels of genetic variation in nuclear microsatellite DNA and mitochondrial DNA markers of samples collected before and after this El Nino event. Changes in microsatellite frequency are sensitive enough to detect low population sizes before there is a significant loss of diversity in a population, whereas mitochondrial markers only show losses of diversity.

Caccone said that although some populations had mortality rates of up to 90%, only one population from a single island showed strong evidence of a "genetic bottleneck," suggesting that the El Niño-induced disturbance affected populations very differently even within the same species.

"Our study points out that there was a low population size on the island of Marchena during the same period in which there was serious volcanic activity as well as the El Nino," said Yale graduate student Scott Glaberman, a principal author of the study. "Since both of these forces could have acted on the population, it shows the importance of knowing the major forces influencing survival and reproduction to best interpret the results of genetic tests.

"The most striking result of our study is that although marine iguanas on some islands had a rather high mortality due to El Niño, the genetic consequences were mostly absent," said author Sebastian Steinfartz a postdoctoral fellow. "This unique study shows that natural populations may be able to balance even severe short term climatic disturbances, and that such fluctuations will not necessarily have long-term negative consequences on the population structure."

"Basic surveys and ecology of organisms are not the most glamorous aspects of research, but if used together with the exciting genetic approach in our study, they make for a very powerful approach," said Glaberman.

"This underscores the importance of having baseline studies for any population of interest, and the value of archiving samples for the use of future research," Caccone said. "It sets the basis for future research to determine which environmental and biological factors make specific populations more vulnerable than others."

Other authors on the study are Deborah Lanterbecq at Yale, Cruz Marquez at the Charles Darwin Research Station, Santa Cruz, Galápagos, Ecuador and Kornelia Rassmann in Germany. Granting from the National Geographic Society, the German Research Community, the Belgian American Educational Foundation, and the Yale Institute for Biospheric Studies supported the research.

Citation: Public Library of Science (PLoS): December 12, 2007.

Adapted from materials provided by Yale University

Using Carbon Nanotubes To Seek And Destroy Anthrax Toxin And Other Harmful Proteins

Scientists have long been interested in wrapping proteins around carbon nanotubes, and the process is used for various applications in imaging, biosensing, and cellular delivery. But this new study at Rensselaer is the first to remotely control the activity of these conjugated nanotubes.

A team of Rensselaer researchers led by Ravi S. Kane, professor of chemical and biological engineering, has worked for nearly a year to develop a means to remotely deactivate protein-wrapped carbon nanotubes by exposing them to invisible and near-infrared light. The group demonstrated this method by successfully deactivating anthrax toxin and other proteins.

"By attaching peptides to carbon nanotubes, we gave them the ability to selectively recognize a protein of interest -- in this case anthrax toxin -- from a mixture of different proteins," Kane said. "Then, by exposing the mixture to light, we could selectively deactivate this protein without disturbing the other proteins in the mixture."

By conjugating carbon nanotubes with different peptides, this process can be easily tailored to work on other harmful proteins, Kane said. Also, employing different wavelengths of light that can pass harmlessly through the human body, the remote control process will also be able to target and deactivate specific proteins or toxins in the human body. Shining light on the conjugated carbon nanotubes creates free radicals, called reactive oxygen species. It was the presence of radicals, Kane said, that deactivated the proteins.

Kane's new method for selective nanotube-assisted protein deactivation could be used in defense, homeland security, and laboratory settings to destroy harmful toxins and pathogens. The method could also offer a new method for the targeted destruction of tumor cells. By conjugating carbon nanotubes with peptides engineered to seek out specific cancer cells, and then releasing those nanotubes into a patient, doctors may be able to use this remote protein deactivation technology as a powerful tool to prevent the spread of cancer.

Kane's team also developed a thin, clear film made of carbon nanotubes that employs this technology. This self-cleaning film may be fashioned into a coating that -- at the flip of a light switch -- could help prevent the spread of harmful bacteria, toxins, and microbes.

"The ability of these coatings to generate reactive oxygen species upon exposure to light might allow these coatings to kill any bacteria that have attached to them," Kane said. "You could use these transparent coatings on countertops, doorknobs, in hospitals or airplanes -- essentially any surface, inside or outside, that might be exposed to harmful contaminants."

Kane said he and his team will continue to hone this new technology and further explore its potential applications.

Details of the project are outlined in the article "Nanotube-Assisted Protein Deactivation" in the December issue of Nature Nanotechnology.

Co-authors of the paper include Department of Chemical and Biological Engineering graduate students Amit Joshi and Shyam Sundhar Bale; postdoctoral researcher Supriya Punyani; Rensselaer Nanotechnology Center Laboratory Manager Hoichang Yang; and professor Theodorian Borca-Tasciuc of the Department of Mechanical, Aerospace, and Nuclear Engineering.

The group has filed a patent disclosure for their new selective nanotube-assisted protein deactivation technology. The research project was funded by the U.S. National Institutes of Health and the National Science Foundation.

Adapted from materials provided by Rensselaer Polytechnic Institute.

Bio Technology

I selected to do Bio Technology for my electives, So i'll have to learn something on biotech. Ok, let's start with some definitions.

According to Oxford medical dictionary it is,

"the development of techniques for the application of biological processes to the production of materials of use in medicine and industry"

NIH gives following definition,

"A set of biological techniques developed through basic research and now applied to research and product development."



So it's all about finding new solutions to old problems. that's cool isn't it.