Study: How do plants adapt to cold ambient temperatures and frost?

As plants are sessile organisms, they must be highly flexible in their ability to adapt to a wide range of environmental conditions in order to survive. Researchers from the Department of Plant Physiology at the RPTU Kaiserslautern are investigating plant adaptation mechanisms, particularly to abiotic stress factors such as light intensity or temperature. They have now reached a new milestone: PhD student Annalisa John has used the model plant thale cress (Arabidopsis thaliana) in her research work to decode which cellular mechanisms that plants use to adapt to cold temperatures and frost. The results of the study have been published in the renowned scientific journal “The Plant Cell”.

Quelle: IDW Informationsdienst Wissenschaft

New study warns: global warming and invasive species threaten seagrass meadows in the Mediterranean

The rise in sea temperature and salinity in the Mediterranean and the immigration of invasive species could endanger the structure and biodiversity of its seagrass meadows, which play an essential role in the marine environment. This is the conclusion reached by an international team of researchers led by the Leibniz Centre for Tropical Marine Research (ZMT) in a study recently published in the journal „Science of The Total Environment“.

Quelle: IDW Informationsdienst Wissenschaft

Zebrafish Navigate to Find Their Comfortable Temperature

Zebrafish are smaller than your little finger, with a brain no more than half the size of a pinhead. Yet these animals possess an efficient navigation system that enables them to find their way back to spots in the water where the temperature suits them. This has been revealed in a recent study by the University of Bonn and University Hospital Bonn together with the Technical University of Munich (TUM), whose findings have been published in the journal “Current Biology.”

Quelle: IDW Informationsdienst Wissenschaft

Deciphering nature’s climate shield: Plant diversity stabilises soil temperature

A new study has revealed a natural solution to mitigate the effects of climate change, such as extreme weather events. Researchers from Leipzig University, the Friedrich Schiller University Jena, the German Centre for Integrative Biodiversity Research Halle-Jena-Leipzig (iDiv) and other research institutions have discovered that high plant diversity acts as a buffer against fluctuations in soil temperature. This buffer can then be of vital importance to ecosystem processes. They have just published their new findings in the journal Nature Geoscience.

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Heat Sensor Protects the Venus Flytrap From Fire

The sensory hairs of the Venus flytrap contain a heat sensor that warns the plant of bush fires. It reacts to rapid temperature jumps, as Würzburg researchers have discovered.

Quelle: IDW Informationsdienst Wissenschaft

Roots are capable of measuring heat on their own, new study shows

Plant roots have their own thermometer to measure the temperature of the soil around them and they adjust their growth accordingly. Through extensive experiments, a team led by Martin Luther University Halle-Wittenberg (MLU), was able to demonstrate that roots have their own temperature sensing and response system. In a new study in „The EMBO journal“, the scientists also provide a new explanation for how roots themselves detect and react to higher temperatures. The results could help develop new approaches for plant breeding.

Quelle: IDW Informationsdienst Wissenschaft

6.1 million data points prove the influence of climate on global fungal occurrence

A new study by Bayreuth scientists Dr. Franz-Sebastian Krah and Prof. Dr. Claus Bässler has shown that temperature has a significant influence on the timing and duration of fungal fruiting in key areas of the world. The research results were published in the journal „Ecology Letters“ and shed new light on the global impact of climate change on occurrences of fungi in nature.

Quelle: IDW Informationsdienst Wissenschaft

Cold is beneficial for healthy aging

A lower body temperature is one of the most effective mechanisms to prolong the lifespan of animals. Writing in ‘Nature Aging’, a working group at the University of Cologne’s CECAD Cluster of Excellence in Aging Research has now described precisely how this works. The scientists show that cold can prevent the pathological aggregation of proteins typical for two aging-associated neurodegenerative diseases.

Quelle: IDW Informationsdienst Wissenschaft

Global study by the University of Bayreuth shows influences of climate change on terrestrial ecosystems

In a study published in Nature Geoscience, plant ecologists at the University of Bayreuth have shown how global climate change is impacting the Earth’s terrestrial ecosystems. Changes in vegetation activity could in most cases be explained by temperature and soil moisture changes, while changes in solar radiation and atmospheric CO₂ levels seldom played a dominant role. In some of the ecosystems studied, years of increased vegetation activity have been followed by decreases. Such trend reversals raise the question of whether terrestrial ecosystems will continue to make large contributions to the sequestration of atmospheric carbon.

Quelle: IDW Informationsdienst Wissenschaft

Temperature perception influences protein degradation and lifespan

Proteins in the gut of the nematode C. elegans are not degraded when its temperature sensors are disturbed / At the same time, the worm’s lifespan is extended

Quelle: IDW Informationsdienst Wissenschaft

The last 12,000 years show a more complex climate history than previously thought

An international team of researchers from Germany, the United Kingdom, Switzerland, Canada and France reveal the complexity of temperature trends over the past 12,000 years.

Quelle: IDW Informationsdienst Wissenschaft

Worldwide assessment of protected areas

Protected areas are among the most effective tools for preserving biodiversity. However, new protected areas are often created without considering existing ones. This can lead to an overrepresentation of the biophysical characteristics, such as temperature or topography, that define a certain area. A research group at the Technical University of Munich (TUM) has now assessed a global analysis of the scope of protection of various biophysical conditions.

Quelle: IDW Informationsdienst Wissenschaft

An innovative imaging technique for dynamic optical nanothermometry

A new imaging technique can measure temperature in 2D, without contact, and in just a snap.

Quelle: Sciencedaily

At what temperature the weather becomes a problem

When extreme heat becomes more frequent and temperatures remain high for extended periods of time, as it is currently in Canada and in the American Northwest, physiological stress increases in humans, animals and crops. Prof. Senthold Asseng, director of the World Agricultural Systems Center at the Technical University of Munich (TUM), provides an overview of thresholds and adaptation strategies.

Quelle: IDW Informationsdienst Wissenschaft

Heavy water makes biological clocks tick more slowly – How to Retard Time for Cells

Scientists at Leipzig University, in collaboration with colleagues from Germany and England, have succeeded in reversibly slowing down cellular processes. A team of biophysicists led by Professor Josef Alfons Käs and Dr Jörg Schnauß were able to show in experiments that cells can be transferred into slow motion without changing the temperature. From a physical point of view, such possibilities have so far only been available in the context of the theory of relativity. They recently published their findings in the renowned journal “Advanced Materials”.

Quelle: IDW Informationsdienst Wissenschaft

Extreme CO2 greenhouse effect heated up the young Earth

Although sun radiation was relatively low, the temperature on the young Earth was warm. An international team of geoscientists has found important clues that high levels of carbon dioxide in the atmosphere were responsible for these high temperatures. It only got cooler with the beginning of plate tectonics, as the CO2 was gradually captured and stored on the emerging continents.

Quelle: IDW Informationsdienst Wissenschaft

Novel hydrogel carriers for anti-cancer drugs offer new hope for cancer treatment

Hydrogels are often used as drug delivery systems, but to be effective carriers for anti-cancer drugs, they need to be responsive to varied stimuli in the tumor microenvironment. Now, scientists have developed novel hydrogels to effectively deliver drugs to tumor sites in response to temperature and pH changes in the tumor microenvironment. These multi-stimuli-responsive hydrogels can eliminate remnant cancer cells following tumor excision through controlled drug release, offering hope for effective cancer treatment.

Quelle: Sciencedaily

Fossils show consequences of ocean warming

Scientists at the Museum für Naturkunde Berlin and the University of Exeter in Great Britain have studied the ecological effects on the marine fauna of a rapid and unusually intense phase of global warming during the Jurassic period about 182 million years ago. Using fossils, the researchers have shown that the rise in seawater temperature drastically reduced species diversity and biomass, and that the composition of the communities at that time changed permanently. The study shows the possible long-term consequences of the current climate crisis for marine ecosystems.

Quelle: IDW Informationsdienst Wissenschaft

Implications of quantum metabolism and natural selection for the origin of cancer cells and tumor progression

Energy transfer in material solids is driven primarily by differences in intensive thermodynamic quantities such as pressure and temperature. The crucial observation  in quantum-theoretical models was the consideration of the heat capacity as associated with the vibrations of atoms in a crystalline solid. However, living organisms are essentially isothermal. Because of very little differences in temperature between different parts of a cell it is assumed that energy flow in living organisms is mediated by differences in the turnover time of various metabolic processes in the cell, which occur in cyclical fashion. It has been shown that the cycle time of these metabolic processes is related to the metabolic rate, that is the rate at which the organism transforms the free energy of whatever source into metabolic work, maintenance of constant temperature and structuraland functional organization of the cells. Quantum Metabolism exploits the methodology of the quantum theory of solids to provide a molecular level which derives new rules relating metabolic rate and body size.

Davies P, Lloyd A, Demetrius LA, Tuszynski, JA (2012) Implications of quantum metabolism and natural selection for the origin of cancer cells and tumor progression. Citation: AIP Advances 2, 011101 (2012); doi: 10.1063/1.3697850

Einstein A (1920), Schallausbreitung in teilweise dissozieirten Gasen

Einstein A (1924) Quantentheorie des einatomigen, idealen Gases

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

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.

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

The carcinogenic effect of various multi-walled carbon nanotubes (MWCNTs) after intraperitoneal injection in rats

Non-neoplastic histopathological findings in the abdominal cavity. A: High-power view of anti-podoplanin immunohistochemistry showing single MWCNT A (high dose) nanotubes in the tissue (arrows). B: High-power view of anti-podoplanin immunohistochemistry showing single asbestos fibers in the tissue (arrows). C: H & E, high-power view of granuloma induced by MWCNT A (low dose) nanotubes including single nanotube (arrow, 25×). D: H & E, high-power view of granuloma induced by asbestos including single fiber (arrow, 40×). Rittinghausen et al. Particle and Fibre Toxicology 2014 11:59   doi:10.1186/s12989-014-0059-z
Non-neoplastic histopathological findings in the abdominal cavity. A: High-power view of anti-podoplanin immunohistochemistry showing single MWCNT A (high dose) nanotubes in the tissue (arrows). B: High-power view of anti-podoplanin immunohistochemistry showing single asbestos fibers in the tissue (arrows). C: H & E, high-power view of granuloma induced by MWCNT A (low dose) nanotubes including single nanotube (arrow, 25×). D: H & E, high-power view of granuloma induced by asbestos including single fiber (arrow, 40×).
Rittinghausen et al. Particle and Fibre Toxicology 2014 11:59 doi:10.1186/s12989-014-0059-z

Susanne Rittinghausen, Anja Hackbarth, Otto Creutzenberg, Heinrich Ernst, Uwe Heinrich, Albrecht Leonhardt and Dirk Schaudien

Abstract

Background

Biological effects of tailor-made multi-walled carbon nanotubes (MWCNTs) without functionalization were investigated in vivo in a two-year carcinogenicity study. In the past, intraperitoneal carcinogenicity studies in rats using biopersistent granular dusts had always been negative, whereas a number of such studies with different asbestos fibers had shown tumor induction. The aim of this study was to identify possible carcinogenic effects of MWCNTs. We compared induced tumors with asbestos-induced mesotheliomas and evaluated their relevance for humans by immunohistochemical methods.

Methods

A total of 500 male Wistar rats (50 per group) were treated once by intraperitoneal injection with 109 or 5 × 109 WHO carbon nanotubes of one of four different MWCNTs suspended in artificial lung medium, which was also used as negative control. Amosite asbestos (108 WHO fibers) served as positive control. Morbid rats were sacrificed and necropsy comprising all organs was performed. Histopathological classification of tumors and, additionally, immunohistochemistry were conducted for podoplanin, pan-cytokeratin, and vimentin to compare induced tumors with malignant mesotheliomas occurring in humans.

Results

Treatments induced tumors in all dose groups, but incidences and times to tumor differed between groups. Most tumors were histologically and immunohistochemically classified as malignant mesotheliomas, revealing a predominantly superficial spread on the serosal surface of the abdominal cavity. Furthermore, most tumors showed invasion of peritoneal organs, especially the diaphragm. All tested MWCNT types caused mesotheliomas. We observed highest frequencies and earliest appearances after treatment with the rather straight MWCNT types A and B. In the MWCNT C groups, first appearances of morbid mesothelioma-bearing rats were only slightly later. Later during the two-year study, we found mesotheliomas also in rats treated with MWCNT D – the most curved type of nanotubes. Malignant mesotheliomas induced by intraperitoneal injection of different MWCNTs and of asbestos were histopathologically and immunohistochemically similar, also compared with mesotheliomas in man, suggesting similar pathogenesis.

Conclusion

We showed a carcinogenic effect for all tested MWCNTs. Besides aspect ratio, curvature seems to be an important parameter influencing the carcinogenicity of MWCNTs.

Continue reading „The carcinogenic effect of various multi-walled carbon nanotubes (MWCNTs) after intraperitoneal injection in rats“