Scientists had believed Geobacter sulfurreducens conducted electricity through common, hair-like appendages called pili. Instead, a researcher at the University of Virginia School of Medicine and his collaborators have determined that the bacteria transmit electricity through immaculately ordered fibers made of an entirely different protein. These proteins surround a core of metal-containing molecules, much like an electric cord contains metal wires. This “nanowire,” however, is 100,000 times smaller than the width of a human hair.

This tiny-but-tidy structure, the researchers believe, could be tremendously useful for everything from harnessing the power of bioenergy to cleaning up pollution to creating biological sensors. It could actually serve as the bridge between electronics and living cells.

“There are all sorts of implanted medical devices that are connected to tissue, like pacemakers with wires, and this could lead to applications where you have miniature devices that are actually connected by these protein filaments,” said UVA’s Edward H. Egelman, PhD. “We can now imagine the miniaturization of many electronic devices generated by bacteria, which is pretty amazing.”

Small but Effective

Geobacter bacteria play important roles in the soil, including facilitating mineral turnover and even cleaning up radioactive waste. They survive in environments without oxygen, and they use nanowires to rid themselves of excess electrons in what can be considered their equivalent to breathing. These nanowires have fascinated scientists, but it is only now that researchers at UVA, Yale and the University of California, Irvine, have been able to determine how G. sulfurreducens uses these organic wires to transmit electricity.

“The technology [to understand nanowires] didn’t exist until about five years ago, when advances in cryo-electron microscopy allowed high resolution,” said Egelman, of UVA’s Department of Biochemistry and Molecular Genetics. “We have one of these instruments here at UVA, and, therefore, the ability to actually understand at the atomic level the structure of these filaments. … So this is just one of the many mysteries that we’ve now been able to solve using this technology, like the virus that can survive in boiling acid, and there will be others.”

He noted that by understanding the natural world, including at the smallest scales, scientists and manufacturers can get many valuable insights and useful ideas. “One example that comes to mind is spider silk, which is made from proteins just like these nanowires, but is stronger than steel,” he said. “Over billions of years of evolution, nature has evolved materials that have extraordinary qualities, and we want to take advantage of that.”

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Humans tend to be preoccupied with beauty — a person’s attractiveness is associated with academic performance, career success and economic mobility. But despite its importance, scientists know little about the genetic basis for having a pretty face. In the current work, researchers performed a genome-wide association study using genetic information from 4,383 individuals to pinpoint parts of the genome linked to facial beauty. They had volunteers score yearbook photos based on attractiveness from participants with European ancestry and compared the scores to each person’s genetic information. The researchers identified several genes related to facial attractiveness, but their roles and relatedness to other human traits varied by sex. In women, certain genetic variations linked to beauty also appeared to be related to genes impacting body mass, while in males, variants were linked to genes affecting blood cholesterol levels.

The study provides new insights into the genetic factors underlying facial attractiveness and highlights the complex relationships between beauty and other human traits. “Similar to many other human traits, there is not a ‘master gene’ that determines a person’s attractiveness,” author Qiongshi Lu observed. “Instead, it is most likely associated with a large number of genetic components with weak effects. Interestingly, sex-specificity is a recurrent pattern observed in almost all the analyses in our study.” The researchers acknowledge, however, that their findings are based on a homogenous group of individuals of the same age and ethnic background. They propose that future analyses including a larger sample size of people from diverse populations and ages will further advance our understanding of this highly valued human trait.

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Throughout evolution, cytomegaloviruses (CMVs) have been capturing genes from their hosts, employing the derived proteins to dampen immune responses and successfully persist within their hosts. Certain CMVs encode homologs of CD48, a molecule found on the surface of most of the leukocytes of the body. CD48 binds to the 2B4 receptor on certain immune cells such as natural killer cells, which play a pivotal role in the rapid recognition and control of viral infections. But the properties and biological relevance of the viral CD48 homologs have not been explored. In the new study, Angulo and colleagues have investigated for the first time the immunomodulatory potential of one of these viral molecules: A43, a CD48 homolog encoded by owl monkey CMV.

The researchers show that A43 binds strongly to 2B4 and is capable of blocking its interaction with CD48. Moreover, the findings reveal how this viral protein interferes with the function of human natural killer cells. Taken together, these results not only underscore the importance of 2B4-mediated immune responses in controlling CMV infections, but also unveil CD48 as a new viral counteract mechanism for subverting immune surveillance. The authors propose that A43 may serve as a CD48 decoy receptor by binding and masking 2B4, thereby impeding effective immune control by cytotoxic lymphocytes during viral infections. According to the authors, the research highlights the potential of using the inhibitory molecule A43 to develop novel therapeutic tools to manipulate aberrant immune responses, such as those linked to autoimmune diseases.

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