STED Images Living Mouse Brain; Vitamin D Receptor in 3D; Arranging Nanoparticles

STED Images Living Mouse Brain; Vitamin D Receptor in 3D; Arranging Nanoparticles

STED Images Living Mouse Brain

Stefan Hell’s team of researchers at the Max Planck Institute for Biophysical Chemistry in Göttingen has used stimulated emission depletion (STED) fluorescence microscopy to record detailed live images inside the brain of a living mouse at a resolution of less than 70 nanometers. The detailed images show neuronal dendritic spines, which form the postsynaptic component of most excitatory synapses. Images taken seven to eight minutes apart revealed that the dendritic spine heads move and change their shape.

As detailed in a Science paper, the researchers created these images in genetically modified mice that produce large quantities of yellow fluorescent protein in their neurons. The fluorescent protein migrates into even the smallest, finest structures of the neuron. "In the future, these super-sharp live images could even show how certain proteins are distributed at the contact points," adds Hell, who developed STED microscopy. With such increasingly detailed images of structures in the brain, Hell’s team hopes to shed light onto the composition and function of the synapses on the molecular level.

View a video of the neurons below:

The Vitamin D Receptor in 3D

Researchers from the Institute of Genetics and Molecular and Cellular Biology in France have created a high-resolution 3D image of the vitamin D receptor. Scientists want to know more about this receptor because vitamin D is involved in diseases such as cancer, rickets and type 1 diabetes. The 3D structure, which was published in an EMBO Journal paper, provides key information on the action mechanism of the receptor at the molecular scale.

Until now, researchers had only studied the structure of two parts of this receptor by producing each part in the laboratory and analyzing the structure individually using crystallography techniques. The entire vitamin D receptor is difficult to crystallize and weighs only 100 kilodaltons. To over come these challenges the researchers produced large quantities of human vitamin D receptor in E. coli and then isolated and flash froze the receptor. They used the microscope to acquire 20,000 images of receptor particles in different orientations and created a 3D reconstruction of the entire receptor by aligning and combining the images. The same approach could be used to study other poorly understood nuclear receptors.

Arranging Nanoparticles

Researchers from led by Chad Mirkin at Northwestern University have used scanning probe block copolymer lithography (SPBCL) to synthesize and place single CdS semiconductor nanoparticles in specific locations on a surface. SPBCL brings together the advantages of scanning probe lithography and bottom-up synthesis and could offer a way to precisely place quantum dots and other binary materials on substrates for use in sensors, solar cells, and electronic devices.

The researchers coated an atomic force microscope tip with an ink solution containing a block copolymer and cadmium chloride salt and then patterned the ink onto a surface using the AFM tip. Exposing the samples to H2S gas created the CdS nanoparticles, and oxygen plasma was applied to remove the block copolymer. The nanoparticle size, which determines their emission wavelength, could be tuned by adjusting the time that the tip was in contact with the substrate. Read more about the process in a NanoLetters paper.

Coffee Break Moment …

If you’ve been itching to download some new apps, there’s a new one from Carl Zeiss. The Light Lab app for iPad, iPhone, and iPod touch lets you simulate fluorescence experiments and check the spectral compatibility for over 500 fluorophores. You can also save your lab’s microscopy configurations using the app.