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news10euJuly/August 2017 | MicroscopyandAnalysisIn a world first, US-based research-ers have used cryo-electron microscopy and synchrotron X-ray analysis to visualise the atomic-resolu-tion structure of a complete bacterial microcompartment shell from the Haliangium ochraceum.As Professor Cheryl Kerfeld from the Department of Energy Plant Research Lab, Michigan State University, US, highlights, these nanoreactors comprise hundreds of copies of five distinct proteins that form hexamers, pentamers, and three types of trimers.The results could help in the design of subcellular nanoreactors in beneficial bacteria and point the way to vulnerable targets in pathogenic bacteria.Using X-ray analysis at Berkeley Lab's Advanced Light Source and the SLAC National Accelerator Laboratory, Stanford University, with cryo-EM, Kerfield and colleagues produced a 8.7 Å resolution cryo-EM map, which was used to place individual structures and phase the crystallographic data.As Kerfeld points out, determining the structure took around two years as the shell is a massive 6.5 megadaltons in size – one megadalton is comparable to the mass of 1 million hydrogen atoms – and contains approximately 300 average-sized proteins."I can remember the first time I saw images of animal cell organelles, taken with an electron microscope... seeing those inspired me and helped shape my career path," says Kerfeld. "I remembered that excitement when I became one of the first people to see this structure."The researchers reckon the structure is likely to become the textbook model of the membrane of primitive bacterial organelles.Research is published in Science.Cryo-EM unravels bacteria shell complexitiesLonely bee secrets exposedEnvironmental scanning electron microscopy has revealed that a social halictid bee has more sensory machinery than solitary relatives. Using a Zeiss EVO 55 with an Everhart–Thornley SE detector, Sarah Kocher, from the US-based Lewis-Sigler Institute for Integrative Genomics, and colleagues, measured the differences in density of tiny, hollow sensory hairs called sensilla on the antennae of 36 adult female bees.They discovered that solitary bees had less hair-like sensilla on the antennae. What's more, the chemical signals used by social and solitary forms of the same species, to identify each other and coordinate tasks, were different.According to Kocher, by investing in higher numbers of sensilla, social bees may increase the number of receptors available and thereby increase the speed and accuracy of their response to social signals.In contrast, solitary females can still recognise relevant stimuli but no longer require dense, costly sensilla to perceive complex social signals.And as she adds: "This study demonstrates that changes in social structure are reflected in changes to the sensory systems of insects."Research is published in PNAS.Astunning confocal fluorescence microscopy image – captured using a Zeiss LSM 710 – reveals the influence of hormones during brain development of Drosophila.The image follows research into a steroid hormone that triggers a vital transition in the early brain development of fruit fly larvae. At this transtition, neural stem cells 'change gear' to produce different types of neuron."Our finding is the first example of hormones regulating time-sensitive gene transitions during neurogenesis, and it offers exciting insights into how problems with hormone signaling could be implicated in neurological diseases," says Dr Mubarak Hussain Syed from the Doe Lab at the University of Oregon. The discovery is set to shed new light on maternal hypothyroidism, a human condition in which too little thyroid is produced and is dangerous for pregnant women and their developing babies."Human brain development requires similar transitions in the type of neurons made by neural stem cells during fetal development," highlights Professor Chris Doe. "Failure to make the full, diverse complement of neurons would be catastrophic for brain development."Research is published in eLife.Shining light on brain developmentFruit fly brain Researchers block signaling of a steroid hormone and show that glial cells (magenta), no longer needed at a particular stage of brain development, are over-produced by neural stems cells (green) SyedSEM image of bee antennae Bernadette Wittwer, University of MelbourneMichigan State University researchers provide first detailed images of bacteria's building blocks