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461.
Ana Carolina Brasileiro Ronildo Alves Benício José Guilherme Gonçalves-Sousa Robson Waldemar Ávila 《Austral ecology》2023,48(7):1274-1291
Anthropogenic changes in habitats are one of the main threats to biodiversity. Understanding how species diversity and their functions are affected by these changes is crucial to assess environmental impacts. In this work, we aim to understand how lizard composition, taxonomic and functional diversity respond to differences in native vegetation regeneration stages (conserved vegetation and open secondary vegetation) and agricultural land use in different vegetation types (Caatinga sensu stricto, Cerrado sensu stricto and Relictual Humid Forest) in Caatinga domain, Brazil. In more degraded areas (open secondary vegetation and agricultural areas), we found a decline in species evenness, shown by greater dominance of few species. Moreover, we found a lower functional evenness in agricultural areas than in areas of conserved vegetation, which suggests that a smaller portion of functional traits present greater dominance in more anthropized areas. We did not detect any significant differences in species richness, but we did registered differences in species composition in Relictual Humid Forest. Contrary to our expectations, lizard abundance was also greater in more degraded areas, probably as a result of the increased abundance of species benefited by anthropization. In this work, we advance the knowledge of how anthropogenic changes influence lizard diversity and emphasize the importance of analysing different facets of diversity and different habitat environments to understand how anthropization affects patterns in community ecology. 相似文献
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463.
Waldemar Preis Annika Bestehorn Johannes Buchner Martin Haslbeck 《Cell stress & chaperones》2017,22(4):541-552
In humans, ten genes encode small heat shock proteins with lens αA-crystallin and αB-crystallin representing two of the most prominent members. The canonical isoforms of αA-crystallin and αB-crystallin collaborate in the eye lens to prevent irreversible protein aggregation and preserve visual acuity. α-Crystallins form large polydisperse homo-oligomers and hetero-oligomers and as part of the proteostasis system bind substrate proteins in non-native conformations, thereby stabilizing them. Here, we analyzed a previously uncharacterized, alternative splice variant (isoform 2) of human αA-crystallin with an exchanged N-terminal sequence. This variant shows the characteristic α-crystallin secondary structure, exists on its own predominantly in a monomer–dimer equilibrium, and displays only low chaperone activity. However, the variant is able to integrate into higher order oligomers of canonical αA-crystallin and αB-crystallin as well as their hetero-oligomer. The presence of the variant leads to the formation of new types of higher order hetero-oligomers with an overall decreased number of subunits and enhanced chaperone activity. Thus, alternative mRNA splicing of human αA-crystallin leads to an additional, formerly not characterized αA-crystallin species which is able to modulate the properties of the canonical ensemble of α-crystallin oligomers. 相似文献
464.
Effects of 253.7 nm ultraviolet radiation on membrane potential and conductance in internodal cells of Nitellopsis obtusa were studied. The radiation caused transient depolarization of plasmalemma and tonoplast and simultaneous increase in electric conductance. These effects were partly reversible and the degree of the recovery depended on the duration of the exposure. In cells with potential difference (between vacuole and external medium) more negative than – 140 mV, the radiation induced an action potential. The hyperpolarized state created by visible light and indole-3-acetic acid was fully suppressed by the radiation. The results are discussed taking into account the data for Chara corallina obtained by C. J. Doughty and A. B. Hope. It is suggested that 253.7 nm radiation inhibits electrogenic proton pumps in the plasmalemma and activates the Cl− channels. 相似文献
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466.
Lebecka Renata Kistowski Michał Dębski Janusz Szajko Katarzyna Murawska Zofia Marczewski Waldemar 《Plant and Soil》2019,441(1-2):317-329
Plant and Soil - This study aims the detection of proteins associated with increased resistance of tubers to necrotrophic bacteria Dickeya solani in tetraploid and diploid potato plants.... 相似文献
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469.
Alexander J. F. Egan Jacob Biboy Inge van't Veer Eefjan Breukink Waldemar Vollmer 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2015,370(1679)
Peptidoglycan (PG) is an essential component in the cell wall of nearly all bacteria, forming a continuous, mesh-like structure, called the sacculus, around the cytoplasmic membrane to protect the cell from bursting by its turgor. Although PG synthases, the penicillin-binding proteins (PBPs), have been studied for 70 years, useful in vitro assays for measuring their activities were established only recently, and these provided the first insights into the regulation of these enzymes. Here, we review the current knowledge on the glycosyltransferase and transpeptidase activities of PG synthases. We provide new data showing that the bifunctional PBP1A and PBP1B from Escherichia coli are active upon reconstitution into the membrane environment of proteoliposomes, and that these enzymes also exhibit DD-carboxypeptidase activity in certain conditions. Both novel features are relevant for their functioning within the cell. We also review recent data on the impact of protein–protein interactions and other factors on the activities of PBPs. As an example, we demonstrate a synergistic effect of multiple protein–protein interactions on the glycosyltransferase activity of PBP1B, by its cognate lipoprotein activator LpoB and the essential cell division protein FtsN. 相似文献
470.
Jenny Krönström Waldemar Karlsson Bengt R. Johansson Susanne Holmgren 《Cell and tissue research》2009,336(2):299-308
Inside the light organs of the bioluminescent (light-producing) crustacean Meganyctiphanes norvegica (krill), numerous capillaries drain haemolymph into the light-producing structure (lantern). We have investigated the arrangement
and function of filamentous material found around the opening of the capillaries. These have been suggested to work as sphincters,
controlling the haemolymph (i.e. oxygen) supply to the lantern and thereby the production of light. Electron microscopy shows
that the filamentous material consists of thick and thin muscle filaments arranged in perpendicular blocks around the opening
of each capillary. The actin probe rhodamine phalloidin has revealed that one component is filamentous actin. Clusters of
vesicle-dense nerve profiles surround the cells containing filamentous material and antibodies against 5-hydroxytryptamine
(5-HT) reveal that 5-HT containing nerves lead to the filamentous area. When exposed to the muscle-relaxing substances papaverine
and verapamil, krill respond with luminescence, suggesting that the sphincter structures are functionally involved in the
control of light production. Treatment with the muscle-contracting drugs Bay K8544 and thapsigargin gives no light response.
Thus, 5-HT stimulates light production in krill; however, a combination of 5-HT and the muscle-relaxing drugs or Bay K8544
potentiates the effect of 5-HT. Thapsigargin quenches the response to 5-HT. Our results corroborate speculations of earlier
authors who have suggested that the sphincter structures are of a muscular nature and important in controlling light production
in krill. However, other parameters in addition to the oxygen supply to the lantern are involved in controlling bioluminescence
in the light organs of M. norvegica.
We acknowledge financial support from the Biodiversity Program of the Swedish Science Research Council and from the Royal
Swedish Academy of Science for supporting work at the Kristineberg Marine Research Center. Electron microscopy equipment was
granted by the Lundberg Research Foundation. 相似文献