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71.
Jasmin Ana Luiza M Torres Henrique MP Nunes Juliana A Passipieri Linda A Jelicks Emerson L Gasparetto David C Spray Antonio C Campos de Carvalho Rosalia Mendez-Otero 《Journal of nanobiotechnology》2011,9(1):4
Background
Stem cell therapy has emerged as a promising addition to traditional treatments for a number of diseases. However, harnessing the therapeutic potential of stem cells requires an understanding of their fate in vivo. Non-invasive cell tracking can provide knowledge about mechanisms responsible for functional improvement of host tissue. Superparamagnetic iron oxide nanoparticles (SPIONs) have been used to label and visualize various cell types with magnetic resonance imaging (MRI). In this study we performed experiments designed to investigate the biological properties, including proliferation, viability and differentiation capacity of mesenchymal cells (MSCs) labeled with clinically approved SPIONs. 相似文献72.
Although cellular damage during cryopreservation of freshwater fish spermatozoa has been reported in several studies, there is a lack of correlation between this damage and the fertility rates of eggs using postthawed milt. The apparent lack of such correlation may be due to other undetected sublethal cryodamage, which could affect the cell functionality and viability. This may be extremely important for freshwater fish spermatozoa whose ability to fertilize the egg requires dilution in water or hypoosmotic solutions, an hazardous environment for the cells. This study tested the change in cell permeability during cryopreservation, using Hoechst 33258 to assess cell permeability. The permeability of spermatozoa at different times after dilution in several hypoosmotic media were investigated. In the first trial, fresh semen, sperm diluted in freezing media (CPT), and freeze/thawed semen were studied. Three CPT were tested (Me2SO, DMA, and methanol). In the second trial, the addition of egg yolk as a membrane stabilizer was investigated. Samples were frozen at -20 degreesC/min in a programmable cooler and thawed in a 25 degreesC water bath. Dilution in the CPTs slightly increased the susceptibility of cells to damage but freezing/thawing caused a dramatic increase in the fragility of cells, which were killed in a few seconds after their contact with the hypoosmotic solutions. Egg yolk provided a significant protection to the membrane, allowing the cells a greater and more prolonged survival in the fertilization media. Samples frozen with Me2SO displayed the best results. These results are consistent with the achieved fertility rates that demonstrated sublethal cryodamage in the function of the sperm membrane that was not detected by standard procedures. Copyright 1998 Academic Press. 相似文献
73.
An exception to the generally conservative nature of plastid gene evolution
is the gene coding for the beta" subunit of RNA polymerase, rpoC2. Previous
work by others has shown that maize and rice have an insertion in the
coding region of rpoC2, relative to spinach and tobacco. To assess the
distribution of this extra coding sequence, we surveyed a broad
phylogenetic sample comprising 55 species from 17 angiosperm families by
using Southern hybridization. The extra coding sequence is restricted to
the grasses (Poaceae). DNA sequence analysis of 11 species from all five
subfamilies within the grass family demonstrates that the extra sequence in
the coding region of rpoC2 is a repetitive array that exhibits more than a
twofold increase in nucleotide substitution, as well as a large number of
insertion/deletion events, relative to the adjacent flanking sequences. The
structure of the array suggests that slipped-strand mispairing causes the
repeated motifs and adds to the mechanisms through which the coding
sequence of plastid genes are known to evolve. Phylogenetic analyses based
on the sequence data from grass species support several relationships
previously suggested by morphological work, but they are ambiguous about
broad relationships within the family.
相似文献
74.
Nucleolar organizer regions are nucleolar components that contain proteins that are stained selectively by silver methods; they can be identified as black dots throughout the nucleolus and are known as silver binding nucleolar organizer regions (AgNOR). The number of AgNOR is related to the cell cycle and the proliferative activity of the cells. We investigated AgNOR using exfoliative cytology smears of potentially malignant oral lesions. Eighty individuals were divided into four equal groups: healthy controls, oral leukoplakia, oral submucous fibrosis and oral squamous cell carcinoma. The mean number of AgNOR in each study group gradually increased from control to oral leukoplakia to oral submucous fibrosis to oral squamous cell carcinoma. The proliferative index was increased in the oral premalignant and malignant patients compared to normal subjects. The mean AgNOR size gradually increased from control to oral leukoplakia to oral submucous fibrosis to oral squamous cell carcinoma. Spherical shaped AgNOR were most common in controls, whereas large, clustered and kidney shapes were most common in oral squamous cell carcinoma. Multiparameter analysis of AgNOR in oral exfoliative smears is a simple, sensitive and cost-effective method for differentiating premalignant from malignant lesions and can be used in conjunction with routine cytomorphological evaluation. 相似文献
75.
Thaumatocotyle roumillati n. sp. is described from specimens collected in the nasal fossae of the Atlantic stingray, Dasyatis sabina (Lesueur) from the southeastern coast of the United States, off South Carolina. Thaumatocotyle roumillati is distinguished from congeners by the size and shape of its penis as well as the presence of a spinelike accessory piece associated with the penis. 相似文献
76.
Angélica MS Firmo Mônica MP Tognella Saulo R Silva Raynner RRD Barboza Rômulo RN Alves 《Journal of ethnobiology and ethnomedicine》2012,8(1):1-12
Background
Blue Land Crab (Cardisoma guanhumi) is one of the most important crustacean species captured and commercialized in Brazil. Although this species is not considered to be threatened with extinction, populations of C. guanhumi are known to be rapidly diminishing due to heavy harvesting pressures and degradation of their natural habitats, highlighting the necessity of developing and implanting management and protection strategies for their populations. There have been no ethnozoological publications that have focused specifically on C. guanhumi, in spite of importance of this type of information for developing efficient management plans of resource utilization. So, the present work describes the ethnoecological aspects of the capture and commercialization of C. guanhumi by a fishing community in northeastern Brazil.Methods
Field work was carried out in the municipality of Mucuri, Bahia in Brazil, between the months of January and March/2011 through the use of open semi-structured interviews with all of the crustacean harvesters in city who acknowledged their work in capturing this species, totaling 12 interviewees. The informants were identified through the use of the "snowball" sampling technique. In addition to the interviews themselves, the "guided tour" technique and direct observations was employed.Results
According all the interviewees, the C. guanhumi is popularly called "guaiamum" and is collected in "apicum" zones. They recognize sexual dimorphism in the species based on three morphological characteristics and the harvesters also pointed two stages in the reproductive cycle during the year and another phase mentioned by the interviewees was ecdysis. All of the interviewed affirmed that the size and the quantities C. guanhumi stocks in Mucuri have been diminishing. All of the interviewees agreed that the species and other mangrove resources constituted their principal source of income. The harvesters dedicated three to five days a week to collect Blue Land Crabs and the principal technique utilized for capturing is a trap called a "ratoeira" (rat-trap).Conclusions
The results of the present work demonstrated that the community retains a vast and important volume of knowledge about C. guanhumi that could subsidize both scientific studies and the elaboration of viable management and conservation strategies for this species. 相似文献77.
Louis Grillet Laurent Ouerdane Paulina Flis Minh Thi Thanh Hoang Marie-Pierre Isaure Ryszard Lobinski Catherine Curie Stéphane Mari 《The Journal of biological chemistry》2014,289(5):2515-2525
Iron (Fe) is essential for virtually all living organisms. The identification of the chemical forms of iron (the speciation) circulating in and between cells is crucial to further understand the mechanisms of iron delivery to its final targets. Here we analyzed how iron is transported to the seeds by the chemical identification of iron complexes that are delivered to embryos, followed by the biochemical characterization of the transport of these complexes by the embryo, using the pea (Pisum sativum) as a model species. We have found that iron circulates as ferric complexes with citrate and malate (Fe(III)3Cit2Mal2, Fe(III)3Cit3Mal1, Fe(III)Cit2). Because dicotyledonous plants only transport ferrous iron, we checked whether embryos were capable of reducing iron of these complexes. Indeed, embryos did express a constitutively high ferric reduction activity. Surprisingly, iron(III) reduction is not catalyzed by the expected membrane-bound ferric reductase. Instead, embryos efflux high amounts of ascorbate that chemically reduce iron(III) from citrate-malate complexes. In vitro transport experiments on isolated embryos using radiolabeled 55Fe demonstrated that this ascorbate-mediated reduction is an obligatory step for the uptake of iron(II). Moreover, the ascorbate efflux activity was also measured in Arabidopsis embryos, suggesting that this new iron transport system may be generic to dicotyledonous plants. Finally, in embryos of the ascorbate-deficient mutants vtc2-4, vtc5-1, and vtc5-2, the reducing activity and the iron concentration were reduced significantly. Taken together, our results identified a new iron transport mechanism in plants that could play a major role to control iron loading in seeds. 相似文献
78.
Requirement for SWI/SNF chromatin-remodeling complex in Tat-mediated activation of the HIV-1 promoter 下载免费PDF全文
Tréand C du Chéné I Brès V Kiernan R Benarous R Benkirane M Emiliani S 《The EMBO journal》2006,25(8):1690-1699
Activation of the human immunodeficiency virus type-1 (HIV-1) promoter in infected cells requires the sequential recruitment of several cellular factors to facilitate the formation of a processive elongation complex. The nucleosomal reorganization of the HIV-1 long terminal repeat (LTR) observed upon Tat stimulation suggests that chromatin-remodeling complexes could play a role during this process. Here, we reported that Tat interacts directly with Brm, a DNA-dependent ATPase subunit of the SWI/SNF chromatin-remodeling complex, to activate the HIV-1 LTR. Inhibition of Brm via small interfering RNAs impaired Tat-mediated transactivation of an integrated HIV-1 promoter. Furthermore, Brm is recruited in vivo to the HIV-1 LTR in a Tat-dependent manner. Interestingly, we found that Tat/Brm interaction is regulated by Tat lysine 50 acetylation. These data show the requirement of Tat-mediated recruitment of SWI/SNF chromatin-remodeling complex to HIV-1 promoter in the activation of the LTR. 相似文献
79.
Champica K. Bodinayake Ajith DeS Nagahawatte Vasantha Devasiri Niroshana J. Dahanayake Gaya B. Wijayaratne Nayani P. Weerasinghe Madureka Premamali Tianchen Sheng Bradley P. Nicholson Harshanie A. Ubeysekera Ruvini MP Kurukulasooriya Aruna D. de Silva Truls
stbye Christopher W. Woods L. Gayani Tillekeratne 《PLoS neglected tropical diseases》2022,16(5)
80.
Haifa Laroussi Yanis Aoudache Emilie Robert Virginie Libante Louise Thiriet Dominique Mias-Lucquin Badreddine Douzi Yvonne Roussel Isaure Chauvot
de
Beauchêne Nicolas Soler Nathalie Leblond-Bourget 《Nucleic acids research》2022,50(14):8127
Integrative and conjugative elements (ICEs) are important drivers of horizontal gene transfer in prokaryotes. They are responsible for antimicrobial resistance spread, a major current health concern. ICEs are initially processed by relaxases that recognize the binding site of oriT sequence and nick at a conserved nic site. The ICESt3/Tn916/ICEBs1 superfamily, which is widespread among Firmicutes, encodes uncanonical relaxases belonging to a recently identified family called MOBT. This family is related to the rolling circle replication initiators of the Rep_trans family. The nic site of these MOBT relaxases is conserved but their DNA binding site is still unknown. Here, we identified the bind site of RelSt3, the MOBT relaxase from ICESt3. Unexpectedly, we found this bind site distantly located from the nic site. We revealed that the binding of the RelSt3 N-terminal HTH domain is required for efficient nicking activity. We also deciphered the role of RelSt3 in the initial and final stages of DNA processing during conjugation. Especially, we demonstrated a strand transfer activity, and the formation of covalent DNA-relaxase intermediate for a MOBT relaxase. 相似文献