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931.
Jolanta J. Adamczyk 《Ecological Research》2011,26(3):547-554
Macrofungal communities were investigated in four associations of xerothermic swards: Festucetum pallentis, Origano-Brachypodietum, Adonido-Brachypodietum pinnati and Diantho-Armerietum elongatae in a Jurassic area of the Częstochowa Upland (southern Poland). A total of 47 species were recorded. The self-organising
map (SOM)—an unsupervised algorithm for artificial neural networks—was used to recognise patterns in the macrofungal communities
of diverse xerothermic swards. Only two associations were mycologically similar: Origano-Brachypodietum and Adonido-Brachypodietum pinnati. Species with high and significant IndVal (the species indicator value) for each investigated phytocoenoses are presented.
The presence of macrofungal species and the participation of indicator species were connected with habitat factors of plant
associations, as documented by the IndVal application. In the least fertile phytocoenoses, macrofungal communities were poor
with few indicator species. The more fertile phytocoenoses had richer and more varied communities of macrofungi with higher
numbers of indicator species. The ordering methods applied in this study were very effective for analyzing the macrofungal
communities existing in plant associations. 相似文献
932.
The most accepted hypothesis of magnetoreception for social insects is the ferromagnetic hypothesis which assumes the presence of magnetic material as a sensor coupled to sensitive structures that transmit the geomagnetic field information to the nervous system. As magnetite is the most common magnetic material observed in living beings, it has been suggested as basic constituent of the magnetoreception system. Antennae and head have been pointed as possible magnetosensor organs in social insects as ants, bees and termites. Samples of three antenna joints: head-scape, scape-pedicel and pedicel-third segment joints were embedded in epoxi resin, ultrathin sectioned and analyzed by transmission electron microscopy. Selected area electron diffraction patterns and X-ray energy dispersive spectroscopy were obtained to identify the nanoparticle compound. Besides iron oxides, for the first time, nanoparticles containing titanium have been identified surrounded by tissue in the antennae of ants. Given their dimension and related magnetic characteristics, these nanoparticles are discussed as being part of the magnetosensor system. 相似文献
933.
Huiru Lu Jun Chen Hui Huang Mengxue Zhou Qing Zhu Shao Q. Yao Zhifang Chai Yi Hu 《Biometals》2017,30(4):599-607
Both monoamine oxidase B (MAO-B) and iron accumulation are associated with neurologic diseases including Parkinson’s disease. However, the association of iron with MAO-B activity was poorly understood. Here we took advantage of highly sensitive and specific fluorescence probes to examine the change in MAO-B activity in human dopaminergic neuroblastoma (SH-SY5Y) cells upon iron exposure. Both ferric and ferrous ions could significantly enhance the activity of MAO-B, instead of MAO-A, in SH-SY5Y cells. In addition, iron-induced increase in MAO-B probe fluorescence could be prevented by pargyline and other newly developed MAO-B inhibitors, suggesting that it was MAO-B activity-dependent. These findings may suggest MAO-B is an important sensor in iron-stressed neuronal cells. 相似文献
934.
Background
Although capable to evolve, viruses are generally considered non-living entities because they are acellular and devoid of metabolism. However, the recent publication of the genome sequence of the Mimivirus, a giant virus that parasitises amoebas, strengthened the idea that viruses should be included in the tree of life. In fact, the first phylogenetic analyses of a few Mimivirus genes that are also present in cellular lineages suggested that it could define an independent branch in the tree of life in addition to the three domains, Bacteria, Archaea and Eucarya. 相似文献935.
Background
Overlapped genes originate by a) loss of a stop codon among contiguous genes coded in different frames; b) shift to an upstream initiation codon of one of the contiguous genes; or c) by overprinting, whereby a novel open reading frame originates through point mutation inside an existing gene. Although overlapped genes are common in viruses, it is not clear whether overprinting has led to new genes in prokaryotes. 相似文献936.
Katelin D. Pearson 《Biodiversity and Conservation》2018,27(11):3007-3018
Distributions of taxa across time and space are central to understanding biodiversity and biotic change, yet currently available occurrence data, drawn from biodiversity specimen records and observational datasets, are often insufficient to answer many driving questions. Records of “associated taxa,” taxa co-occurring with a specimen at the time and place of collection, have the potential to fill data gaps and expand the spatiotemporal scope of current occurrence records. I developed a method to extract associated taxon records from 84,328 digitized specimen records and examined the potential of these data to improve the quantity and quality of existing species occurrence data. Adding associated taxon records increased the size of the test dataset by 18.5%, spanned multiple decades (1937–2016), and potentially extended the known range of 217 taxa in Florida and up to 1500 taxa in the United States, demonstrating the capacity of these records to deepen our understanding of changes in the distributions of taxa on Earth. These results suggest that increased attention to documenting associated taxa could be a promising way to maximize the impact of every collecting event. 相似文献
937.
Roles of Peroxisome Proliferator-Activated Receptor Gamma on Brain and Peripheral Inflammation 总被引:1,自引:0,他引:1
Sonia Villapol 《Cellular and molecular neurobiology》2018,38(1):121-132
Peroxisome proliferator-activated receptor gamma (PPARγ) has been implicated in the pathology of numerous diseases involving diabetes, stroke, cancer, or obesity. It is expressed in diverse cell types, including vessels, immune and glial cells, and neurons. PPARγ plays crucial roles in the regulation of cellular differentiation, lipid metabolism, or glucose homeostasis. PPARγ ligands also exert effects on attenuating degenerative processes in the brain, as well as in peripheral systems, and it has been associated with the control of anti-inflammatory mechanisms, oxidative stress, neuronal death, neurogenesis, differentiation, and angiogenesis. This review will highlight key advances in the understanding of the PPARγ-related mechanisms responsible for neuroprotection after brain injuries, both ischemia and traumatic brain injury, and it will also cover the natural and synthetic agonist for PPARγ, angiotensin receptor blockers, and PPARγ antagonists, used in experimental and clinical research. A better understanding of the pleiotropic mechanisms and applications of these drugs to improve the recovery and to repair the acute and chronic induced neuroinflammation after brain injuries will pave the way for more effective therapeutic strategies after brain deficits. 相似文献
938.
By using hematoxylin staining, peculiarities of chromatin of diapausing silkworm embryos were studied in normal and parthenogenetic development. A direct correlation was revealed between the number of interphase chromatin grains and the number of chromosomes in the nucleus; polyploidization of cells in embryo was studied at the stage of diapause. The polyploidization in parthenogenesis is not restricted to endomitotic chromosome set doubling, as it includes 6n-nuclei. To explain the more diverse spectrum of polyploid cells in parthenogenesis (as compared with the norm), it is necessary to take into account fusion of cleavage nuclei, which is realized by the cytoplasmic mechanism of karyogamy in the absence of fertilization. On squash preparations, for the first time, we identified primordial germ cells of the diapausing embryo, which are characterized by less compact chromatin, especially in the zygotic variant of development; by larger nuclei and cytoplasm; and by an irregular number and size of nucleoli. Estimation of ploidy of the primary germ cells in parthenogenesis by counting “loose” chromatin grains in diapause is possible and indicates polyploidization in the primordial germ cells. This explains an inevitable admixture of tetraploid eggs in the grain of diploid parthenoclones and its absence in normal development. The cytological method used has revealed a spiral arrangement of chromatin grains on the internal nuclear surface at different ploidy levels. 相似文献
939.
Michael C. F. Proctor 《Plant Growth Regulation》2010,62(3):233-240
Desiccation-tolerant plants vary greatly in the rate of recovery of chlorophyll-fluorescence parameters on re-wetting. This
paper seeks general curves that will adequately describe the course of recovery, and quantify the variations in rate within
and between species. Recovery of F
v
/F
m is closely fitted in many species by a logistic curve, starting from zero, on a logarithmic time-scale (seconds to days).
Such curves have three parameters, an asymptote at maximum F
v
/F
m, a half-recovery time (T
0.5), and a slope constant (S). If F
v
/F
m in dry material differs substantially from zero, four-parameter logistic curves can give a better fit. In either case, T
0.5 and S show wide ecologically-significant variation. Some species show anomalously high values of F
v
/F
m in the early minutes of recovery, alongside low absolute values of F
m; these invite further investigation. Logistic curves give good fits to the recovery in light of Φ
PSII, q
P, and photosynthetic CO2 fixation. The results provide the means to quantify ‘high-inertia’ versus ‘low-inertia’ strategies of desiccation tolerance,
and to explore the factors influencing recovery time and rate, and the reasons for some discrepancies from the common course
of recovery. There is substantial overlap in all parameters between the bryophytes and pteridophytes studied. 相似文献
940.
Dean C Adams 《BMC evolutionary biology》2010,10(1):72