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New uLIPSTIC technology can track physical interactions between cells, like the above depiction of a dendritic cell activating a T cell. | Photo credit: Rockefeller University
A fundamental goal of basic biology is to understand how various types of cells work together to form tissues, organs, and organ systems. While recent efforts to catalog the different cell types in each tissue of the human body are a step in the right direction, they address only one piece of the puzzle. The great mystery of how these cells communicate with each other remains unaddressed and unaddressed.
Since the advent of single-cell mRNA sequencing, researchers have struggled to connect the dots and explain how diverse cells come together to form tissue. The various existing methods for cataloging cell-cell interactions have deficiencies. In early efforts, which involved direct observation under a microscope, interacting cells could not be recovered for further analysis. With the advanced imaging techniques used in later developments, how cells might interact could only be inferred based on their structure and proximity to other cells. Neither approach captured the true physical interactions and signal exchange between cell membranes.
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Now, a team of American scientists, led by Sandra Nakandakari-Higa of Rockefeller University, has designed a new tool called uLIPSTIC that lays the foundation for a dynamic map that tracks the physical interactions between different cells and is capable of generating the set of all interactions between cells. uLIPSTIC is the culmination of work started in 2018, which in principle can allow researchers to directly observe any interaction between cells in vivo. The work is described in a recent article in Nature. “With uLIPSTIC we can ask how cells work together, how they communicate, and what messages they transfer,” said Rockefeller’s Gabriel D. Victora.
The new tool involves labeling cellular structures that touch when two cells make fleeting “kiss-and-run” contact before separating; If one cell “kissed” another, it would leave a mark much like that of a lipstick, allowing easy identification and quantification of cell-cell interaction.
The original platform that was designed had limited applications, recording only a specific type of interaction between cells. The team decided to design a universal platform and created uLIPSTIC. In the original version of LIPSTIC, a “donor” cell used an enzyme taken from bacteria to place a labeled peptide tag on the surface of an “acceptor” cell upon contact. “If you fill the associated cells with enough enzyme and target, you can make any pair of cells capable of labeling LIPSTIC without needing to know in advance what molecules these cells will use for their interaction,” Victora said.
Therefore, uLIPSTIC does not require prior knowledge of molecules, ligands or receptors. In theory, scientists can now smear uLIPSTIC on any cell, without preconceived notions of how it will interact with its environment, and observe physical interactions between cells. The hope is that, over time, uLIPSTIC will become a key tool for generating comprehensive atlases of cells that interact to form tissues.
Synchrotron on solar energy
(Left) The main building of the Australian Synchrotron after solar panels were installed on its iconic circular roof. (Right) The building before it became a plot of land. | Photo credit: ANSTO
THE Australian Nuclear Science and Technology Organization (ANSTO) Australian Synchrotron is one of the country’s main research facilities and is located in Clayton, south-east of Melbourne. A synchrotron is a type of particle accelerator, a variant of the cyclotron in which the beam of accelerated particles travels around a fixed, closed-loop path, one of whose main uses is as a powerful source of X-rays.
The roof of the main building of the Australian Synchrotron has been covered with more than 3,200 solar panels covering a total area of 6,600 square meters. The installation was completed in five months. The 1,668 kWh solar panel system and inverter will cover part of the Australian synchrotron’s total energy needs. It is expected to save ANSTO more than 2 million kWh per year and reduce its carbon footprint by more than 1,680 tons of CO2 one year. The anticipated monetary savings are approximately A$2 million (US$1.3 million) over the next five years. Michael James, director of the facility, said: “The size of our roofs, together with the extensive and uninterrupted exposure to sunlight at our location within the Monash precinct, was a significant incentive for us to become more energy efficient.”
A galactic emission and the Big Bang
Images of the 10 discovered LyC-leaking galaxies, with Astrosat’s deep UV field in the background. | Photo Credit: Inter-University Center for Astronomy and Astrophysics, Pune
The Indian multi-wavelength research satellite AstroSat, launched in September 2015, has detected ionizing photons from a rare type of galaxy known as Lyman Continuum (LyC) leaks. The discovery of 10 of these galaxies, from the peak era in the history of cosmic star formation, makes it the first coherent sample of LyC leaks at this time.
The hydrogen atom is known to absorb photons only at wavelengths shorter than about 912 angstroms (Å, which is one-tenth of a billionth of a meter), known as the Lyman limit, corresponding to a frequency of 3.29 million gigahertz and a photon energy of 13.6 electron volts. The Lyman limit corresponds to the lowest energy photons absorbed by the hydrogen atom when an electron bound to a hydrogen nucleus can escape freely. Photon energies above the Lyman limit lie entirely in the UV region of the electromagnetic spectrum, and therefore LyC photon energies lie in the extreme UV region. Therefore, detection of photons in this energy range by AstroSat was only possible with its onboard UV Imaging Telescope (UVIT) instrument.
“Detecting ionizing ultraviolet radiation from such galaxies is extremely challenging and was only possible thanks to the unique capabilities and high sensitivity of UVIT,” said Suraj Dhiwar, lead author of this research work, which was recently published in The letters from the astrophysical diary.
During the first billion years of the Big Bang, the universe went through a major phase transition known as the reionization phase, a process in which neutral hydrogen atoms dissociated into protons and electrons when hit by high-speed ultraviolet photons. energy in the LyC emission range. . Understanding cosmic reionization and the sources responsible for it remains one of the major unsolved problems in astronomy.
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“Emission from the Lyman continuum can be easily absorbed or scattered by the interstellar medium or the circumgalactic medium of its host galaxies. Even when some of these ionizing photons manage to leave the galaxy’s environment, they can be absorbed by the vast intergalactic medium between us and the galaxy. This is what makes its discovery a rare event in astrophysics. Thanks to the resolution and sensitivity of UVIT, it allowed us to create a deep UV field in the far UV filter,” said Kanak Saha, associate professor at the Inter-University Center for Astronomy and Astrophysics, Pune.
Most interestingly, these LyC photons have wavelengths extending up to ~600 Å, falling into the extreme ultraviolet regime, the shortest UV wavelength at which a galaxy has yet been imaged. These galaxies are located 8 to 9 billion light years from Earth and have intense star formation rates, with some of them forming massive young stars at a rate 100 times that of the Milky Way. In addition to ultraviolet observation from Astrosat, the Hubble Space Telescope was used to obtain optical/infrared images and spectroscopy of these rare galaxies.