- MeSH
- Mental Processes MeSH
- Humans MeSH
- Neuronal Plasticity * MeSH
- Video Games * psychology MeSH
- Research MeSH
- Check Tag
- Humans MeSH
During the millions of years of evolution, photosynthetic organisms have adapted to almost all terrestrial and aquatic habitats, although some environments are obviously more suitable for photosynthesis than others. Photosynthetic organisms living in low-light conditions require on the one hand a large light-harvesting apparatus to absorb as many photons as possible. On the other hand, the excitation trapping time scales with the size of the light-harvesting system, and the longer the distance over which the formed excitations have to be transferred, the larger the probability to lose excitations. Therefore a compromise between photon capture efficiency and excitation trapping efficiency needs to be found. Here we report results on the whole cells of the green sulfur bacterium Chlorobaculum tepidum. Its efficiency of excitation energy transfer and charge separation enables the organism to live in environments with very low illumination. Using fluorescence measurements with picosecond resolution, we estimate that despite a rather large size and complex composition of its light-harvesting apparatus, the quantum efficiency of its photochemistry is around ~87% at 20 °C, ~83% at 45 °C, and about ~81% at 77 K when part of the excitation energy is trapped by low-energy bacteriochlorophyll a molecules. The data are evaluated using target analysis, which provides further insight into the functional organization of the low-light adapted photosynthetic apparatus.
- MeSH
- Bacteriochlorophyll A physiology MeSH
- Chlorobi physiology MeSH
- Fluorescence MeSH
- Fluorometry methods MeSH
- Photochemistry * MeSH
- Photosynthesis * MeSH
- Adaptation, Physiological MeSH
- Energy Transfer physiology MeSH
- Light-Harvesting Protein Complexes metabolism MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Polypropylene (PP) belongs among the most important commodity plastics due to its widespread application. The color of the PP products can be achieved by the addition of pigments, which can dramatically affect its material characteristics. To maintain product consistency (dimensional, mechanical, and optical), knowledge of these implications is of great importance. This study investigates the effect of transparent/opaque green masterbatches (MBs) and their concentration on the physico-mechanical and optical properties of PP produced by injection molding. The results showed that selected pigments had different nucleating abilities, affecting the dimensional stability and crystallinity of the product. The rheological properties of pigmented PP melts were affected as well. Mechanical testing showed that the presence of both pigments increased the tensile strength and Young's modulus, while the elongation at break was significantly increased only for the opaque MB. The impact toughness of colored PP with both MBs remained similar to that of neat PP. The optical properties were well controlled by the dosing of MBs, and were further related to the RAL color standards, as demonstrated by CIE color space analysis. Finally, the selection of appropriate pigments for PP should be considered, especially in areas where dimensional and color stability, as well as product safety, are highly important.
- MeSH
- Fungi MeSH
- Elastic Modulus MeSH
- Plastics * MeSH
- Polypropylenes * MeSH
- Excipients MeSH
- Publication type
- Journal Article MeSH
The aim of this study was to assess the phylogenetic relationships, ecology and ecophysiological characteristics of the dominant planktic algae in ice-covered lakes on James Ross Island (northeastern Antarctic Peninsula). Phylogenetic analyses of 18S rDNA together with analysis of ITS2 rDNA secondary structure and cell morphology revealed that the two strains belong to one species of the genus Monoraphidium (Chlorophyta, Sphaeropleales, Selenastraceae) that should be described as new in future. Immotile green algae are thus apparently capable to become the dominant primary producer in the extreme environment of Antarctic lakes with extensive ice-cover. The strains grew in a wide temperature range, but the growth was inhibited at temperatures above 20 °C, indicating their adaptation to low temperature. Preferences for low irradiances reflected the light conditions in their original habitat. Together with relatively high growth rates (0.4-0.5 day(-1)) and unprecedently high content of polyunsaturated fatty acids (PUFA, more than 70% of total fatty acids), it makes these isolates interesting candidates for biotechnological applications.
- MeSH
- Biodiversity * MeSH
- Chlorophyta classification genetics metabolism MeSH
- Phytoplankton classification genetics isolation & purification metabolism MeSH
- Adaptation, Physiological MeSH
- Lakes MeSH
- Ice Cover * MeSH
- Fatty Acids, Unsaturated metabolism MeSH
- RNA, Ribosomal, 18S genetics MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Antarctic Regions MeSH
MAIN CONCLUSION: The basal streptophyte Klebsormidium and the advanced Zygnema show adaptation to terrestrialization. Differences are found in photoprotection and resistance to short-term light changes, but not in CO 2 acquisition. Streptophyte green algae colonized land about 450-500 million years ago giving origin to terrestrial plants. We aim to understand how their physiological adaptations are linked to the ecological conditions (light, water and CO2) characterizing modern terrestrial habitats. A new Klebsormidium isolate from a strongly acidic environment of a former copper mine (Schwarzwand, Austria) is investigated, in comparison to Klebsormidium cf. flaccidum and Zygnema sp. We show that these genera possess different photosynthetic traits and water requirements. Particularly, the Klebsormidium species displayed a higher photoprotection capacity, concluded from non-photochemical quenching (NPQ) and higher tolerance to high light intensity than Zygnema. However, Klebsormidium suffered from photoinhibition when the light intensity in the environment increased rapidly, indicating that NPQ is involved in photoprotection against strong and stable irradiance. Klebsormidium was also highly resistant to cellular water loss (dehydration) under low light. On the other hand, exposure to relatively high light intensity during dehydration caused a harmful over-reduction of the electron transport chain, leading to PSII damages and impairing the ability to recover after rehydration. Thus, we suggest that dehydration is a selective force shaping the adaptation of this species towards low light. Contrary to the photosynthetic characteristics, the inorganic carbon (C i ) acquisition was equivalent between Klebsormidium and Zygnema. Despite their different habitats and restriction to hydro-terrestrial environment, the three organisms showed similar use of CO2 and HCO3- as source of Ci for photosynthesis, pointing out a similar adaptation of their CO2-concentrating mechanisms to terrestrial life.
- MeSH
- Dehydration MeSH
- Species Specificity MeSH
- Ecology MeSH
- Ecosystem MeSH
- Phenotype MeSH
- Photosynthesis physiology radiation effects MeSH
- Adaptation, Physiological * MeSH
- Carbon Dioxide metabolism MeSH
- Charophyceae physiology radiation effects MeSH
- Light MeSH
- Water physiology MeSH
- Desiccation MeSH
- Publication type
- Journal Article MeSH
- Comparative Study MeSH
- MeSH
- Fundulidae * MeSH
- Adaptation, Physiological MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
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- Keywords
- omezování odpadu,
- MeSH
- Humans MeSH
- Food Packaging MeSH
- Plastics MeSH
- Recycling MeSH
- Green Chemistry Technology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
Pathological states in the central nervous system lead to dramatic changes in the activity of neuroactive substances in the extracellular space, to changes in ionic homeostasis and often to cell swelling. To quantify changes in cell morphology over a certain period of time, we employed a new technique, three-dimensional confocal morphometry. In our experiments, performed on enhanced green fluorescent protein/glial fibrillary acidic protein astrocytes in brain slices in situ and thus preserving the extracellular microenvironment, confocal morphometry revealed that the application of hypotonic solution evoked two types of volume change. In one population of astrocytes, hypotonic stress evoked small cell volume changes followed by a regulatory volume decrease, while in the second population volume changes were significantly larger without subsequent volume regulation. Three-dimensional cell reconstruction revealed that even though the total astrocyte volume increased during hypotonic stress, the morphological changes in various cell compartments and processes were more complex than have been previously shown, including swelling, shrinking and structural rearrangement. Our data show that astrocytes in brain slices in situ during hypotonic stress display complex behaviour. One population of astrocytes is highly capable of cell volume regulation, while the second population is characterized by prominent cell swelling, accompanied by plastic changes in morphology. It is possible to speculate that these two astrocyte populations play different roles during physiological and pathological states.
- MeSH
- Astrocytes pathology ultrastructure MeSH
- Financing, Organized MeSH
- Animals, Genetically Modified MeSH
- Glial Fibrillary Acidic Protein analysis MeSH
- Microscopy, Confocal methods MeSH
- Humans MeSH
- Models, Animal MeSH
- Brain pathology ultrastructure MeSH
- Mice MeSH
- Brain Diseases pathology MeSH
- Green Fluorescent Proteins MeSH
- Imaging, Three-Dimensional MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Review MeSH
