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971.
Andreas Faissner Jan Kruse Klaus Kühn Melitta Schachner 《Journal of neurochemistry》1990,54(3):1004-1015
The J1 glycoproteins can be obtained in multiple forms in the soluble fraction of developing and adult mouse brain tissue. They are recovered as two forms of apparent molecular weights of 160,000 and 180,000 (J1-160) from adult mouse brain and as forms of apparent molecular weights of 200,000 and 220,000 (J1-220) from developing brain. J1-160 and J1-220 share common epitopes but are considered as separate entities, with J1-220 being immunochemically closely related if not identical to tenascin. Based on the observation that J1 immunoreactivity appears on basement membrane and interstitial collagens after denervation of the neuromuscular junction in adult rodents, we became interested in investigating the binding properties of J1 glycoproteins to extracellular matrix constituents in vitro. Both J1-160 and J1-220 bound to collagens type I-VI and IX but not to laminin, fibronectin, bovine serum albumin, or gelatin under hypotonic buffer conditions. Under isotonic buffer conditions, J1-220 bound to all collagen types, whereas J1-160 bound only to collagen types V and VI with values that could be examined by Scatchard analysis. Binding of J1-220 to collagens displayed two binding constants (KD) between 1.5 and 4.4 X 10(-9) and 1.8 and 5.5 X 10(-8) M, respectively, under hypotonic buffer conditions and a single KD of 2.1-8.0 X 10(-8) M under isotonic buffer conditions. Binding of J1-160 to collagens had an apparent KD of 1.9-8.0 X 10(-9) M under hypotonic buffer conditions. Under isotonic buffer conditions, binding constants of J1-160 to collagen types V and VI were approximately 2 X 10(-8) M. Binding of J1-220 to collagen type I could be inhibited by J1-220, J1-160, and collagen type VI but not by fibronectin or gelatin. Conversely, binding of J1-160 was inhibited by J1-220, J1-160, and collagen type VI (in order of decreasing efficacy of competition). J1-160 and J1-220 were retained on a heparin-agarose column and eluted in a salt gradient at approximately 0.5 M NaCl. The formation of the J1-heparin complexes was inhibited 100-fold more efficiently by heparin than by chondroitin sulfate. These experiments show that J1 glycoproteins resemble in many respects the extracellular matrix constituents fibronectin, laminin, vitronectin, and von Willebrand factor. 相似文献
972.
Prezygotic barriers may represent effective mechanisms to avoid the deleterious effects of inbreeding. This study reports the existence of distance-dependent prezygotic barriers in self-compatible Alstroemeria aurea, a clonal herb native to temperate forests of the southern Andes. We analyzed pollen germination and tube growth as indicators of donor-recipient affinity using crossing distances of 1, 10, and 100 m. We used allozyme electrophoresis to determine the actual genetic relatedness between donor and recipient ramets. Pollen germination was not affected by distance between mates, but the number of pollen tubes reaching the base of the style increased strongly with distance between donor and recipient. This pattern was related to an increase in genetic dissimilarity with distance between mates. In contrast, pollen tube-style interactions did not change with distance when we restricted analysis to individuals at different distances that appeared to be genetically identical. This test implied genetic dissimilarity as the critical factor affecting pollen performance. We propose that the existence of prezygotic barriers might contribute to the high degree of genetic mixing exhibited by some clonal species. 相似文献
973.
Short- and long-term changes in species composition, plant biomass production, and litter decomposition after cessation of grazing were examined in a Mediterranean grassland with high dominance of annual species and strong seasonality in biomass production. Short-term changes were assessed during three consecutive years in plots previously exposed to different grazing pressures and compared to plots in long-term (30–40 years) exclosures. Short-term cessation of grazing led in the short-term to an increase in relative biomass of annual crucifers and tall annual and perennial grasses, while biomass of annual legumes, annual thistles and short annual grasses decreased. Consequently, similarity increased between vegetation recently excluded from grazing and vegetation in long-term protected plots. Our research showed that in systems with high dominance of grasses and annual species, the rapid changes in plant species composition that occur after grazing cessation were associated with a fast recovery of the potential for biomass production to levels found in long-term protected plots, while litter decomposition rate did not change even after long-term cessation of grazing. Moreover, previous history of grazing did not affect plant litter decomposition, despite higher litter quality in grazed treatments. This study provides new insights about the processes involved in the diverse responses of ecosystem functions resulting from shifts in species composition associated with grazing cessation and land use change in Mediterranean grasslands. 相似文献
974.
Dr. Michel Stephane Heya Romario García-Ponce Beatriz Amari Medina Soto Dr. María Julia Verde-Star Dr. Adolfo Soto-Domínguez David Gilberto García-Hernandez Dr. Odila Saucedo-Cárdenas Dr. Marcelo Hernández-Salazar Gloria Arely Guillén-Meléndez 《化学与生物多样性》2023,20(10):e202300463
Over the last decade, liver diseases have become a global problem, with approximately two million deaths per year. The high increase in the mortality rate of these diseases is mostly related to the limitations in the understanding of the evolutionary clinical cases of liver diseases, the low delivery of drugs in the liver, the non-specific administration of drugs, and the side effects generated at the systemic level by conventional therapeutic agents. Today it is common knowledge that phytochemicals have a high curative potential, even in the prevention and/or reversibility of liver disorders; however, even using these green molecules, researchers continue to deal with the same challenges implemented with conventional therapeutic agents, which limits the pharmacological potential of these friendly molecules. On the other hand, the latest advances in nanotechnology have proven that the use of nanocarriers as a delivery system for green active ingredients, as well as conventional ones, increases the pharmacological potential of these active ingredients due to their physicochemical characteristics (size, Zeta potential, etc.,) moldable depending on the therapeutic objective; in addition to the above, it should be noted that in recent years, nanoparticles have been developed for the specific delivery of drugs towards a specific target (stellar cells, hepatocytes, Kupffer cells), depending on the clinical state of the disease in the patient. The present review addresses the challenges of traditional medicine and green nanomedicine as alternatives in the treatment of liver diseases. 相似文献
975.
Lisa-Marie Herlevi Marcelo Fernandez-Lahore Guilherme Ferreira 《Biotechnology and bioengineering》2023,120(10):2969-2976
In this work, a novel technique for continuous purification of biologics from a crude feedstock is demonstrated with equipment referred to as Fluidized Bed Adsorption System (FBRAS). The development and validation of such unit operations were performed utilizing lysozyme as a model protein and Relisorb™ SP405/EB as a carrier. The performance of FBRAS to carry out combined clarification and purification was evaluated by capturing of antifungal peptides directly from the lysed broth. The novel technique reduced the number of process unit operations from six to three without having an impact on purity. Overall productivity increased by 250% in comparison to the existing downstream processing routine. 相似文献
976.
Kumie Nojima Taeko Nakadai Yukio Kohno Marcelo E Vazquez Nakahiro Yasuda Shunji Nagaoka 《Biological Sciences in Space》2004,18(3):114-115
To investigate effects of low dose heavy particle radiation to CNS system, we adopted mouse neonatal brain cells in culture being exposed to heavy ions by HIMAC at NIRS and NSRL at BNL. The applied dose varied from 0.05 Gy up to 2.0 Gy. The subsequent biological effects were evaluated by an induction of apoptosis and neuron survival focusing on the dependencies of the animal strains, SCID, B6, B6C3F1, C3H, used for brain cell culture, SCID was the most sensitive and C3H the least sensitive to particle radiation as evaluated by 10% apoptotic criterion. The LET dependency was compared with using SCID and B6 cells exposing to different ions (H, C, Ne, Si, Ar, and Fe). Although no detectable LET dependency was observed in the high LET (55-200 keV/micrometers) and low dose (<0.5 Gy) regions. The survivability profiles of the neurons were different in the mouse strains and ions. In this report, a result of memory and learning function to adult mice after whole-body and brain local irradiation at carbon ion and iron ion. 相似文献
977.
Population structure and landscape genetics in the endangered subterranean rodent Ctenomys porteousi
Fernando J. Mapelli Matías S. Mora Patricia M. Mirol Marcelo J. Kittlein 《Conservation Genetics》2012,13(1):165-181
In order to devise adequate conservation and management strategies for endangered species, it is important to incorporate
a reliable understanding of its spatial population structure, detecting the existence of demographic partitions throughout
its geographical range and characterizing the distribution of its genetic diversity. Moreover, in species that occupy fragmented
habitats it is essential to know how landscape characteristics may affect the genetic connectivity among populations. In this
study we use eight microsatellite markers to analyze population structure and gene flow patterns in the complete geographic
range of the endangered rodent Ctenomys porteousi. Also, we use landscape genetics approaches to evaluate the effects of landscape configuration on the genetic connectivity
among populations. In spite of geographical proximity of the sampling sites (8–27 km between the nearest sites) and the absence
of marked barriers to individual movement, strong population structure and low values of gene flow were observed. Genetic
differentiation among sampling sites was consistent with a simple model of isolation by distance, where peripheral areas showed
higher population differentiation than those sites located in the central area of the species’ distribution. Landscape genetics
analysis suggested that habitat fragmentation at regional level has affected the distribution of genetic variation among populations.
The distance of sampling sites to areas of the landscape having higher habitat connectivity was the environmental factor most
strongly related to population genetic structure. In general, our results indicate strong genetic structure in C. porteousi, even at a small spatial scale, and suggest that habitat fragmentation could increase the population differentiation. 相似文献
978.
Gabriele Rosa da Silva Marcelo Tabarelli Mário Augusto Gonçalves Jardim Eniel David Cruz Maria Fabíola Barros 《Austral ecology》2023,48(6):1132-1153
The exploitation of non-timber forest products has been proposed as a sustainable way to exploit tropical forests, but such an opportunity remains to be proved. Here, we examine the impact of intensive açaí palm (Euterpe oleracea) management on the seed rain and soil seed bank in an estuarine forest landscape with a long history of forest management by locals in the Amazon region. Seed rain (100 80 cm2 collectors) and soil seed bank (100 30 cm2 samples) were monitored through a year across 20 forest stands, covering a gradient of açaí stem density (50–3575 açaí stems per ha). Seed rain and bank were dominated by açaí seeds (85.5%–85.8%) and by excluding them, seed rain and bank were low density and species poor, capturing a tiny subset from the local (17.91%–19.40%) and landscape woody flora (11.82%–14.55%). Moreover, autochthonous and vertebrated-dispersed predominated as well as those from tree species considered useful by locals. Overall, açaí stem density positively affected açaí seed abundance in the seed rain and negatively affected seed pools in the bank in relation to abundance of seeds and vertebrated dispersed, while adult tree species richness and density and accessibility to forest stands were associated with more diversified seed pools. Thereby, forest stands are exposed to different levels of açaí management (high vs. low intensity) supported taxonomically distinct seed pools. Our results suggest that açaí intensification disturbs seed rain and soil seed bank with potential impacts on forest regeneration and the forest integrity standards required to consider açaí fruit production as sustainable according to current legislation. 相似文献
979.
980.
Artoni RF Vicari MR Endler AL Cavallaro ZI de Jesus CM de Almeida MC Moreira-Filho O Bertollo LA 《Genetica》2006,127(1-3):277-284
B chromosomes in Prochilodus lineatus, a migratory neotropical fish, were analyzed in a comparative study among populations from the Dourada lagoon (State of Paraná, Brazil) and from Mogi-Guaçu river (State of São Paulo, Brazil). The data on C-banding and fluorescent in situ hybridization with a satellite DNA probe (SATH1), indicate that the small metacentric B chromosome might correspond to an isochromosome. On the other hand, both populations presented a distinct set of B chromosomes, differentiated either by their number and by the presence of variant B types in the population from Mogi-Guaçu river. The present results indicate that the B chromosomes of P. lineatus should have an ancient origin, and have undergone a differential evolutionary pathway among distinct populations. 相似文献