Schlagwort: population

Heat-lovers are the lucky ones: Insects and climate change

3. Juni 2022
Sparse data often make it difficult to track how climate change is affecting populations of insect species. A new study by the Technical University of Munich (TUM) and the German Centre for Integrative Biodiversity Research (iDiv) has now evaluated an extensive species mapping database (Artenschutzkartierung, ASK) organized by the Bavarian State Office for the Environment (LfU) and assessed the population trends of butterflies, dragonflies and grasshoppers in Bavaria since 1980. The main finding: heat-loving species have been increasing.

Quelle: IDW Informationsdienst Wissenschaft

A two-step adaptive walk in the wild

19. Mai 2022
An international team led by Angela Hancock at the Max Planck Institute for Plant Breeding Research in Cologne (Germany) and scientists from the Associação Projecto Vitó and Parque Natural do Fogo (Cape Verde), the University of Nottingham (UK), and the University of Bochum (Germany) studied a wild thale cress (Arabidopsis thaliana) population that colonized the base of an active stratovolcano. They found that a two-step molecular process rewired nutrient transport in the population. The study, published today in the journal Science Advances, reveal an exceptionally clear case of an adaptive walk in a wild population with broader implications for evolutionary biology and crop improvement.

Quelle: IDW Informationsdienst Wissenschaft

Double agents: How stomach stem cells change allegiance upon injury

6. Mai 2022
A stomach adult stem cell population can fulfill two distinct functions: either help with digestion under normal conditions or take the lead on injury response. Scientists at IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, demonstrate that these functions are two sides of a coin. Upon injury, one “molecular switch” is enough to propel the stem cells from one state to the other. The findings, now published in Cell Stem Cell, could be instrumental in improving our understanding of gastric pathologies.

Quelle: IDW Informationsdienst Wissenschaft

“Vertical farming will play a role in future food production”

13. April 2022
Alternative production systems to provide the growing global population with healthy, nutritious and sustainably produced foodstuffs are currently gaining considerable attention. In this interview, Senthold Asseng, Professor of Digital Agriculture at the Technical University of Munich (TUM), discusses the concept of vertical farming, which will allow agriculture of the future to take place under fully controlled and automated conditions.

Quelle: IDW Informationsdienst Wissenschaft

Thawing permafrost could expose Arctic populations to cancer-causing radon

10. Februar 2022
According to a new study, thawing of permafrost due to climate change could expose the Arctic population to much greater concentrations of the invisible, lung cancer-causing gas Radon.

Quelle: Sciencedaily

Scientists identify malfunctioning brain cells as potential target for Alzheimer’s treatment

11. Dezember 2021
Scientists have identified a rare population of potentially toxic senescent cells in human brains that can serve as a target for a new Alzheimer’s disease treatment.

Quelle: Sciencedaily

Three-dimensional super-resolution microscopy of the inactive X chromosome territory reveals a collapse of its active nuclear compartment harboring distinct Xist RNA foci

22. Februar 2015
3D-SIM-based DAPI intensity classification in the Barr body versus the entire nucleus of C2C12 cells. (A) Mid z-section of a DAPI-stained nucleus. The area below the dashed line illustrates the resolution level obtained by wide-field deconvolution microscopy, for comparison. Inset magnifications show the non-uniformly compacted structure of the Barr body resolvable with 3D-SIM (1) and an arbitrary autosomal region with CDCs (2). Scale bars: 5 μm, insets 1 μm. (B) X chromosome-specific painting (green) of Xi (left) and Xa territories (right) of the same nucleus in different z-sections. Note the high convergence between the painted Xi and the DAPI visualized Barr body (arrowheads). Scale bars: 2 μm, insets 1 μm. (C) 3D DAPI intensity classification exemplified for the nucleus shown in (A). Seven DAPI intensity classes displayed in false-color code ranging from class 1 (blue) representing pixels close to background intensity, largely representing the IC, up to class 7 (white) representing pixels with highest density, mainly associated with chromocenters. Framed areas of the Barr body (inset 1) and a representative autosomal region (inset 2) are shown on the right at resolution levels of 3D-SIM, deconvolution and conventional wide-field microscopy. The Xi territory pervaded by lower DAPI intensities becomes evident only at 3D-SIM resolution, whereas both wide-field and deconvolution microscopy imply a concentric increase of density in the Barr body. In the autosomal region, chromatin assigned to classes 2 to 3 lines compacted CDCs, represented by classes 4 to 6. (D) Left: average DAPI intensity classification profiles with standard deviations evaluated for entire nuclear volumes or the Barr body region only (dark grey bars). Right: over/underrepresentation of the average DAPI intensity class fraction sizes in the Barr body versus entire nuclear volumes (n = 12). Distribution differences on classes between Xi and entire nucleus P <0.001. 3D-SIM, three-dimensional structured illumination microscopy; CDC, chromatin domain cluster; DAPI, 4',6-diamidino-2-phenylindole; FISH, fluorescence in situ hybridization; IC, interchromatin compartment; Xa, active X chromosome; Xi, inactive X chromosome. Smeets et al. Epigenetics & Chromatin 2014 7:8 doi:10.1186/1756-8935-7-8
3D-SIM-based DAPI intensity classification in the Barr body versus the entire nucleus of C2C12 cells. (A) Mid z-section of a DAPI-stained nucleus. The area below the dashed line illustrates the resolution level obtained by wide-field deconvolution microscopy, for comparison. Inset magnifications show the non-uniformly compacted structure of the Barr body resolvable with 3D-SIM (1) and an arbitrary autosomal region with CDCs (2). Scale bars: 5 μm, insets 1 μm. (B) X chromosome-specific painting (green) of Xi (left) and Xa territories (right) of the same nucleus in different z-sections. Note the high convergence between the painted Xi and the DAPI visualized Barr body (arrowheads). Scale bars: 2 μm, insets 1 μm. (C) 3D DAPI intensity classification exemplified for the nucleus shown in (A). Seven DAPI intensity classes displayed in false-color code ranging from class 1 (blue) representing pixels close to background intensity, largely representing the IC, up to class 7 (white) representing pixels with highest density, mainly associated with chromocenters. Framed areas of the Barr body (inset 1) and a representative autosomal region (inset 2) are shown on the right at resolution levels of 3D-SIM, deconvolution and conventional wide-field microscopy. The Xi territory pervaded by lower DAPI intensities becomes evident only at 3D-SIM resolution, whereas both wide-field and deconvolution microscopy imply a concentric increase of density in the Barr body. In the autosomal region, chromatin assigned to classes 2 to 3 lines compacted CDCs, represented by classes 4 to 6. (D) Left: average DAPI intensity classification profiles with standard deviations evaluated for entire nuclear volumes or the Barr body region only (dark grey bars). Right: over/underrepresentation of the average DAPI intensity class fraction sizes in the Barr body versus entire nuclear volumes (n = 12). Distribution differences on classes between Xi and entire nucleus P Smeets et al. Epigenetics & Chromatin 2014 7:8 doi:10.1186/1756-8935-7-8

Daniel Smeets, Yolanda Markaki, Volker J Schmid, Felix Kraus, Anna Tattermusch, Andrea Cerase, Michael Sterr, Susanne Fiedler, Justin Demmerle, Jens Popken, Heinrich Leonhardt, Neil Brockdorff, Thomas Cremer1, Lothar Schermelleh and Marion Cremer

Abstract

Background

A Xist RNA decorated Barr body is the structural hallmark of the compacted inactive X territory in female mammals. Using super-resolution three-dimensional structured illumination microscopy (3D-SIM) and quantitative image analysis, we compared its ultrastructure with active chromosome territories (CTs) in human and mouse somatic cells, and explored the spatio-temporal process of Barr body formation at onset of inactivation in early differentiating mouse embryonic stem cells (ESCs).

Results

We demonstrate that all CTs are composed of structurally linked chromatin domain clusters (CDCs). In active CTs the periphery of CDCs harbors low-density chromatin enriched with transcriptionally competent markers, called the perichromatin region (PR). The PR borders on a contiguous channel system, the interchromatin compartment (IC), which starts at nuclear pores and pervades CTs. We propose that the PR and macromolecular complexes in IC channels together form the transcriptionally permissive active nuclear compartment (ANC). The Barr body differs from active CTs by a partially collapsed ANC with CDCs coming significantly closer together, although a rudimentary IC channel system connected to nuclear pores is maintained. Distinct Xist RNA foci, closely adjacent to the nuclear matrix scaffold attachment factor-A (SAF-A) localize throughout Xi along the rudimentary ANC. In early differentiating ESCs initial Xist RNA spreading precedes Barr body formation, which occurs concurrent with the subsequent exclusion of RNA polymerase II (RNAP II). Induction of a transgenic autosomal Xist RNA in a male ESC triggers the formation of an ‘autosomal Barr body’ with less compacted chromatin and incomplete RNAP II exclusion.

Conclusions

3D-SIM provides experimental evidence for profound differences between the functional architecture of transcriptionally active CTs and the Barr body. Basic structural features of CT organization such as CDCs and IC channels are however still recognized, arguing against a uniform compaction of the Barr body at the nucleosome level. The localization of distinct Xist RNA foci at boundaries of the rudimentary ANC may be considered as snap-shots of a dynamic interaction with silenced genes. Enrichment of SAF-A within Xi territories and its close spatial association with Xist RNA suggests their cooperative function for structural organization of Xi.

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