Inscuteable: No longer inscrutable

The structure and function of a controller of stem cell division

An important complex forming the core of the cell division apparatus in stem cells has been imaged using the Macromolecular Crystallography beamlines, I04 and I04-1 at Diamond Light Source. As recently reported in Nature Communications, the spindle orientation protein known as LGN bound to an adapter protein known as Inscuteable in a tetrameric arrangement, which drove asymmetric stem cell division.

Stem cells are undifferentiated cells that have the capacity to differentiate into specialised cells. In a developing embryo, stem cells are the foundation of all other cells, whereas in adults, they can aid repair by replenishing lost tissue. To ensure a physiological balance between differentiated and undifferentiated cells, stem cells undergo asymmetric division to give rise to an identical daughter stem cell and a differentiated cell.

Asymmetric division occurs when there is an unequal segregation of cellular contents. For this to occur, the line of division of the cell (known as the axis) must be carefully positioned. The stem cells use polarity proteins, such as Par3, to determine the location of this axis, and then proteins such as LGN and Inscuteable (Insc) help to align the mitotic spindle to the axis of polarity.

Despite the importance of such a process, little is known about the interactions between the proteins. Dr Marina Mapelli, Group Leader at the European Institute of Oncology in Milan and Dr Simone Culurgioni, Post-Doctoral Research Associate here at Diamond, along with scientists from the Italian Institute of Technology, plus the European Molecular Biology Laboratory in Grenoble set out to solve the crystal structure of LGN bound to Insc. They saw that the proteins were intertwined in a fascinating tetrameric arrangement and found that Insc alone had impressive anti-proliferative properties.

>Read more on the Diamond Light Source website

Figure : On the left, a stem cell orienting (movement highlighted by the red arrow) its mitotic spindle (in green) in order to partition its cellular components (in pink and yellow) unequally in the two daughter cells; one is retaining the stem state (in pink) and the other one is committed to differentiate (in yellow). On the right, the structure of Insc:LGN complex governing this asymmetric cell division process. Insc:LGN complex assembles in highly stable intertwinned tetrameric structure (Insc in blue and purple, LGN in yellow and orange respectively
Entire image here.

Major upgrade of the NCD beamline

The NCD beamline, now NCD-SWEET, devoted to Small Angle and Wide Angle X-ray Scattering (SAXS, WAXS), is offering users further experimental possibilities and higher quality data.

The SAXS beamline of ALBA has gone through a major upgrade in 2017. Upgraded items in the SAXS WAXS experimental techniques (SWEET) involve a new monochromator system, a new photon counting detector (Pilatus 1M), a new sample table with an additional rotating stage, and a beam conditioning optics with µ-focus and GISAXS options.

The original double crystal monochromator (DCM) has been replaced by a channel-cut silicon (1 1 1), improving the beam stability at sample position up to 0.9% and 0.4% of the beam size horizontally and vertically, respectivelly.

>Read more on the ALBA website

Figure: Vertical beam profile with the Be lenses into the beam (Horizontal axis unit is mm). The plot is the derivative of an edge scan along the vertical direction. The horizontal beam profile shows a gaussian shape as well.

Modifications to novel non-fullerene small molecule acceptor in organic thin film

… for solar cells demonstrates improved power conversion efficiency.

Scientists from the Imperial College London, Monash University, CSIRO, and King Abdullah University of Science and Technology have reported an organic thin film for solar cells with a non-fullerene small molecule acceptor that achieved a power conversion efficiency of just over 13 per cent.

By replacing phenylalkyl side chains in indacenodithieno[3,2-b]thiophene-based non-fullerene acceptor (ITIC) with simple linear chains to form C8-ITIC, they improved the photovoltaic performance of the material.

C8-ITIC was blended with a fluorinated analog of the donor polymer PBDB-T to form bulk-heterojunction thin films.

The research was recently published in Advanced Materials.

Dr Xuechen Jiao of McNeill Research Group at Monash University carried out grazing incidence wide angle X-ray scattering (GIWAXS) measurements at the Australian Synchrotron to gain morphological information on pure and blended thin films.

“By changing the chemical structure of the organic compound, a promising boost in efficiency was successfully achieved in an already high-performing organic solar cells” said Jiao.

>Read more on the Australian Synchrotron website