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51.
Patrice Facy Annie-Pierre Seve Michelle Hubert Michel Monsigny Jean Hubert 《Experimental cell research》1990,190(2)
The nuclear sugar-binding components (i.e., lectinlike molecules) were analyzed using isolated and membrane-depleted nuclei after incubation in the presence of fluorescein-labeled neoglycoproteins. This analysis was performed before and during the in vitro differentiation of HL60 cells into monocytes by PMA treatment and into granulocytes by DMSO treatment. The nucleoli of undifferentiated and differentiated HL60 cells were not labeled, unlike the nucleoli of other mammalian cells studied so far. This peculiarity allowed us to quantitatively analyze by flow cytometry the changes in the lectin activity associated with the extranucleolar territories enriched in ribonucleoprotein complexes. The neoglycoprotein binding was found to be significantly lower in differentiated than in undifferentiated cells. The decrease in neoglycoprotein binding was observed within the first 24 h of DMSO or PMA treatment, just before the arrest of DNA synthesis. Taking into account that the granulocytic differentiation required 72 h of chemical treatment, the extra-nucleolar lectins might be involved in modulation of the DNA synthesis rather than in phenotypic differentiation. These data are discussed in an attempt to reconcile the association of lectins with RNP complexes and their possible involvement in modulation of HL60 cell proliferation. 相似文献
52.
Auer Martin T. Storey Michelle L. Effler Steven W. Auer Nancy A. Sze Philip 《Hydrobiologia》1990,200(1):603-617
The transparency of polluted, hypereutrophic Onondaga Lake, New York, USA has improved substantially in the late 1980's as
a result of reductions in phytoplankton biomass, in the absence of significant reductions in external phosphorus loading.
Much of this improvement has been due to the occurrence of clearing events, e.g. sudden and dramatic increases in transparency.
Field measurements, laboratory experiments, and modelling analyses were utilized to identify processes regulating phytoplankton
standing crop during the spring to fall interval of 1987. Changes in the zooplankton community documented over the past decade
support the conclusion that increased zooplankton grazing has contributed to improvements in transparency. Herbivores now
represent a greater fraction of the zooplankton population and more efficient cladocerans are present in greater numbers.
Biomanipulation practices, e.g. reestablishment of piscivorous species, designed to reduce the abundance of planktivorous
fish species in Onondaga Lake, may serve to reduce pressure on the grazing community and thus result in further improvements
in transparency. 相似文献
53.
54.
Britta Swebilius Singer Larry Gold Sidney T. Shinedling Michelle Colkitt Lawrence R. Hunter David Pribnow Mary Anne Nelson 《Journal of molecular biology》1981,149(3):405-432
We have mapped the mutants isolated by Nelson et al. (1981) that reduce the amount of rIIB protein synthesized during bacteriophage T4 infection of Escherichia coli B and characterized their rIIB expression in vivo. These mutants fall into four distinct groups in terms of mapping and phenotype. We have located the probable site of each mutation on the DNA sequence. We have also analyzed a number of other mutations near the initiating AUG of rIIB with respect to their rIIB expression. In some of these mutants, ribosomal recognition of the wild-type initiating AUG is precluded and so initiation occurs at a different AUG, which, in some instances, we have identified. 相似文献
55.
Apple embryos were treated by cold (0°C) within the fruits, to break their dormancy; the controls were treated at 12°C or at 20°C. Ultrastructural features of meristematic cells in the embryonic axis were compared for each treatment. The organization of the cells of dormant embryos was described: Endoplasmic reticulum consisted in some short rough cisternae; lipid droplets regularly arranged near the plasmalemma constituted a kind of shell; mitochondria had a few cristae; and dictyosomes were rarely observed. All these features are typical of dry seeds. After cold treatments, the only evolution observed was in the endoplasmic reticulum, where highly organized stacks appeared progressively as a function of time at 0°C. An intermediate temperature (12°C) induced similar formations in the reticulum but they were rarely observed and their degree of organization was lower than that obtained at 0°C. At 20°C, endoplasmic reticulum resembled that of the dormant embryo cells. The relation between the appearance of these structures in the reticulum and the disappearance of dormancy induced by cold is discussed.Abbreviations ER
endoplasmic reticulum
- RER
rough endoplasmic reticulum 相似文献
56.
Summary The ecdysial glands (Y organs) of the crab Carcinus maenas regress in the presence of an external parasite, Sacculina carcini. This regression is more or less severe and may lead to complete autolysis. Three gradual stages in this involutionary process are described. In stage I, the gland cells are nearly normal. Nuclei and cytoplasmic organelles remain unchanged, but large vacuoles begin to appear. Stage II corresponds to more or less drastic nuclear pyknosis and cytoplasmic alterations. Myelin figures are large and numerous. Lysosomes and autophagic vacuoles with phosphatase activity are abundant. However, the general cellular architecture remains preserved. Stage III corresponds to irreversible cytolysis; nuclear envelopes and plasma membranes have disappeared. What remains is an accumulation of cellular debris becoming engulfed by circulating hemocytes. Not all of the gland cells of any given Y organ show the same degree of regression; degeneration is asynchronous.Structures seemingly corresponding to absorptive roots of the parasite are seen. Their lumen is coated with microvilli. The putative direct and indirect influences of the rhizocephalan parasite on its host are discussed. Our results on regressing Y organs of parasitized crabs are compared with those on regressing ecdysial glands of insects.Dedicated to the memory of Sir Francis Knowles, the first investigator to examine the ultrastructure of the Y organ of Carcinus maenas
We wish to express our thanks to Professor Berta Scharrer for her critical advice 相似文献
57.
Yanyun Liu Kenny Tsang Michelle Mays Gale Hansen Jeffrey Chiecko Maureen Crames Yangjie Wei Weijie Zhou Chase Fredrick James Hu Dongmei Liu Douglas Gebhard Zhong-Fu Huang Akshita Datar Anthony Kronkaitis Kristina Gueneva-Boucheva Daniel Seeliger Fei Han Saurabh Sen Srinath Kasturirangan Justin M. Scheer Andrew E. Nixon Tadas Panavas Michael S. Marlow Sandeep Kumar 《MABS-AUSTIN》2022,14(1)
58.
59.
Priscilla Y. L. Tng Leonela Z. Carabajal Paladino Michelle A. E. Anderson Zach N. Adelman Rennos Fragkoudis Rob Noad Luke Alphey 《PLoS neglected tropical diseases》2022,16(6)
Aedes aegypti and Ae. albopictus are the main vectors of mosquito-borne viruses of medical and veterinary significance. Many of these viruses have RNA genomes. Exogenously provided, e.g. transgene encoded, small RNAs could be used to inhibit virus replication, breaking the transmission cycle. We tested, in Ae. aegypti and Ae. albopictus cell lines, reporter-based strategies for assessing the ability of two types of small RNAs to inhibit a chikungunya virus (CHIKV) derived target. Both types of small RNAs use a Drosophila melanogaster pre-miRNA-1 based hairpin for their expression, either with perfect base-pairing in the stem region (shRNA-like) or containing two mismatches (miRNA-like). The pre-miRNA-1 stem loop structure was encoded within an intron; this allows co-expression of one or more proteins, e.g. a fluorescent protein marker tracking the temporal and spatial expression of the small RNAs in vivo. Three reporter-based systems were used to assess the relative silencing efficiency of ten shRNA-like siRNAs and corresponding miRNA-like designs. Two systems used a luciferase reporter RNA with CHIKV RNA inserted either in the coding sequence or within the 3’ UTR. A third reporter used a CHIKV derived split replication system. All three reporters demonstrated that while silencing could be achieved with both miRNA-like and shRNA-like designs, the latter were substantially more effective. Dcr-2 was required for the shRNA-like siRNAs as demonstrated by loss of inhibition of the reporters in Dcr-2 deficient cell lines. These positive results in cell culture are encouraging for the potential use of this pre-miRNA-1-based system in transgenic mosquitoes. 相似文献
60.
Yung-Tsi Bolon Bindu Joseph Steven B Cannon Michelle A Graham Brian W Diers Andrew D Farmer Gregory D May Gary J Muehlbauer James E Specht Zheng Jin Tu Nathan Weeks Wayne W Xu Randy C Shoemaker Carroll P Vance 《BMC plant biology》2010,10(1):1-24