Frontiers news briefs: 27 June

The genome of the endophytic bacterium H. frisingense GSF30T identifies diverse strategies in the Herbaspirillum genus to interact with plants

Microbes whose habitat is inside other organisms, such as so-called "endophytic" bacteria that live inside plants, have evolved genes that enable them to overcome their host's defensive mechanisms. But once they have entered the host tissue, such microbes may actually benefit their host, for example, by activating genes that capture atmospheric nitrogen and turn it into natural fertilizer to promote plant growth. Daniel Straub and colleagues from the University of Hohenheim and the Helmholtz Zentrum München, Germany, found that the genomic "toolbox" of the endophytic bacterium H. frisingense, which lives inside grasses, is very different from the toolbox of its closest relatives: unlike other Herbaspirillum species, H. frisingense can fix atmospheric nitrogen to benefits its host, and also uses very different molecular pathways and metabolic modules to enter and survive in host cells. These results can help to identity endophytic bacteria that can be added to soil to improve the yield of crops, without posing a risk to human health or to the environment.

Researcher contact:

Dr. Daniel Straub
Crop Science Institute,
University of Hohenheim, Germany
Email: d.straub@uni-hohenheim.de

URL: http://www.frontiersin.org/evolutionary_and_genomic_microbiology/10.3389/fmicb.2013.00168/abstract

Flies are spectacular in flight, executing precise maneuvers at high speed. But because they are small, they are easily blown off course, and must correct their heading using tiny brains with limited neural resources. When moving forward, images of distant objects travel across the retina more slowly than nearby ones. This geometrical effect, called motion parallax, informs us if we run through the forest that the hovering moon is far off, and that the tree branches whizzing by are near and must be dodged. To determine if flies use motion parallax for corrective flight maneuvers, Stephanie Cabrera and Jamie Theobald, of Florida International University, used a cube with images on the sides to simulate three dimensional forward flight for a fruitfly that was held in place in the cube's center. They found that fruitflies responded more strongly to images that, by virtue of speed, appeared closer. But the crucial variable wasn't absolute speed; it was that some images moved faster than others. These results suggest that tiny fly brains use geometrical clues to identify the closest objects during flight.

Researcher contact:

Prof. Jamie Theobald
Department of Biological Sciences
Florida International University, USA
E-mail: theobald@fiu.edu

URL: http://www.frontiersin.org/Behavioral_Neuroscience/10.3389/fnbeh.2013.00076/abstract

Virtually every known human language features two different classes of words, one for "calling" things – like dogs, clouds, or rumours – and one for saying something about how they are or what they do – dogs bark, clouds are coming, rumours spread. These classes are called nouns and verbs in Western languages, and sits at the very heart of human communication. It was widely believed that separate areas in the brain subserve the production and comprehension of nouns and verbs, based on the outcome of individual studies using functional Magnetic Resonance Imaging (fMRI). Davide Crepaldi, Manuela Berlingeri and colleagues from the University of Milan Bicocca and the University of Milan have put together the evidence coming from those individual studies through a hierarchical clustering technique, and have found that, once results from different experiments are considered as a whole, evidence shows instead that the brain areas deputed to nouns and verbs are mostly overlapping, and the difference in the neural circuitries deputed to either grammatical class scale down to spatial and temporal resolutions that are far out of the grasp of current brain-snapshot techniques. According to the researchers, these results impact deeply on how functional specialization of individual brain areas is currently conceived.

Researcher contact:

Dr. Davide Crepaldi
Department of Psychology
University of Milano-Bicocca, Italy
E-mail: davide.crepaldi1@unimib.it

URL: http://www.frontiersin.org/Human_Neuroscience/10.3389/fnhum.2013.00303/abstract

A double-edged sword: how oncogenes and tumor suppressor genes can contribute to chromosomal instability

Cells rely on an intricate network of signaling pathways to govern a number of processes ranging from tissue repair to programmed cell death. De-regulation of signaling pathways is a hallmark of cancer and responsible for driving tumor formation. Aneuploidy, defined as an abnormal chromosome number, is a distinct feature commonly observed in most solid tumors that arises from errors in cell division during mitosis. While some tumors maintain a stably aneuploid genome, many cancer cells persistently mis-segregate their chromosomes during mitosis, a phenomenon known as chromosomal instability (CIN). CIN is thought to drive the genomic re-shuffling that enables cells to acquire new phenotypes such as drug resistance and is intimately associated with loss of mitotic fidelity. Emerging data show that CIN and de-regulated cell signaling pathways are closely interrelated suggesting the roles that signaling pathways play in the accuracy of mitosis may be underappreciated. These results imply that the induction of CIN can no longer be thought of as a separate event from the cancer-associated driver mutations found in cell signaling pathways. In the context of tumorigenesis this may turn out to be a double-edged sword that combines de-regulated cell cycle progression with the disruption of mitosis to generate the highly complex genomic rearrangements typical of solid tumors. These results change the way we think about how to intervene therapeutically in cancer patients and provide insights on the molecular targets that may contribute significantly to improve patient prognosis.

Researcher contact:

Prof. Duane A. Compton
Department of Biochemistry
Geisel School of Medicine at Dartmouth, USA
Email: duane.a.compton@dartmouth.edu

URL: http://www.frontiersin.org/Molecular_and_Cellular_Oncology/10.3389/fonc.2013.00164/abstract

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