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1.
R. Krattenmacher Rosita Voigt W. Clauss 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,160(2):161-165
Summary Transepithelial electrogenic Na transport (INa) was investigated in the colon of the frog Xenopus laevis with electrophysiological methods in vitro. The short circuit current (Isc) of the voltage-clamped tissue was 24.2±1.8 A·cm-2 (n=10). About 60% of this current was generated by electrogenic Na transport. Removal of Ca2+ from the mucosal Ringer solution stimulated INa by about 120%. INa was not blockable by amiloride (0.1 mmol·l-1), a specific Na-channel blocker in epithelia, but a fully and reversible inhibition was achieved by mucosal application of 1 mmol·l-1 lanthanum (La3-). No Na-self-inhibition was found, because INa increased linearly with the mucosal Na concentration. A stimulation of INa by antidiuretic hormones was not possible. The analysis of fluctuations in the short circuit current (noise analysis) indicated that Na ions pass the apical cell membrane via a Ca-sensitive ion channel. The results clearly demonstrate that in the colon of Xenopus laevis Na ions are absorbed through Ca-sensitive apical ion channels. They differ considerably in their properties and regulation from the amiloride-sensitive Na channel which is typically found in the colon of vertebrates.Abbreviations
G
T
transepithelial conductance
-
I
sc
short circuit current
-
I
Na
transepithelial Na-current
-
m
mucosal
-
s
serosal
-
PDS
power density spectrum
-
f
frequency
-
f
c
corner frequency of the Lorentzian component of the PDS
-
S(f)
power density of the Lorentzian component of the PDS
- So
plateau value of the Lorentzian component of the PDS 相似文献
2.
Kantar A Oggiano N Giorgi PL Coppa GV Gabbianelli R Bruni S Cutrona FM Fiorini R 《Mediators of inflammation》1994,3(7):S21-S24
The effect of nedocromil sodium on the plasma membrane fluidity of polymorphonuclear leukocytes (PMNs) was investigated by measuring steady-state fluorescence anisotropy of 1-[4-trimethylammonium-phenyl]-6-phenyl- 1,3,5-hexatriene (TMA-DPH) incorporated in the membrane. Our results show that nedocromil sodium 300 muM significantly decreased membrane fluidity of PMNs. The decrease in membrane fluidity of PMNs induced by fMLP was abolished in the presence of nedocromil sodium. These data suggest that nedocromil sodium interferes with the plasma membranes of PMNs and modulates their activities. 相似文献
3.
MicroRNA-486-3p Regulates γ-Globin Expression in Human Erythroid Cells by Directly Modulating BCL11A
Valentina Lulli Paolo Romania Ornella Morsilli Paolo Cianciulli Marco Gabbianelli Ugo Testa Alessandro Giuliani Giovanna Marziali 《PloS one》2013,8(4)
MicroRNAs (miRNAs) play key roles in modulating a variety of cellular processes through repression of mRNAs target. The functional relevance of microRNAs has been proven in normal and malignant hematopoiesis. While analyzing miRNAs expression profile in unilineage serum-free liquid suspension unilineage cultures of peripheral blood CD34+ hematopoietic progenitor cells (HPCs) through the erythroid, megakaryocytic, granulocytic and monocytic pathways, we identified miR-486-3p as mainly expressed within the erythroid lineage. We showed that miR-486-3p regulates BCL11A expression by binding to the extra-long isoform of BCL11A 3′UTR. Overexpression of miR-486-3p in erythroid cells resulted in reduced BCL11A protein levels, associated to increased expression of γ-globin gene, whereas inhibition of physiological miR-486-3p levels increased BCL11A and, consequently, reduced γ-globin expression. Thus, miR-486-3p regulating BCL11A expression might contributes to fetal hemoglobin (HbF) modulation and arise the question as to what extent this miRNA might contribute to different HbF levels observed among β-thalassemia patients. Erythroid cells, differentiated from PB CD34+ cells of a small cohort of patients affected by major or intermedia β-thalassemia, showed miR-486-3p levels significantly higher than those observed in normal counterpart. Importantly, in these patients, miR-486-3p expression correlates with increased HbF synthesis. Thus, our data indicate that miR-486-3p might contribute to different HbF levels observed among thalassemic patients and, possibly, to the clinical severity of the disease. 相似文献
4.
Paola Cacchio Rosita Contento Claudia Ercole Giorgio Cappuccio Maria Preite Martinez Aldo Lepidi 《Geomicrobiology journal》2013,30(8):497-509
Much is known about the bacterial precipitation of carbonate rocks, but comparatively little is known about the involvement of microbes in the formation of secondary mineral structures in caves. We hypothesized that bacteria isolated from calcareous stalactites, which are able to mediate CaCO3 precipitation in vitro, play a role in the formation of carbonate speleothems. We collected numerous cultivable calcifying bacteria from calcareous speleothems from Cervo cave, implying that their presence was not occasional. The relative abundance of calcifying bacteria among total cultivable microflora was found to be related to the calcifying activity in the stalactites. We also determined the δ 13C and δ 18 O values of the Cervo cave speleothems from which bacteria were isolated and of the carbonates obtained in vitro to determine whether bacteria were indeed involved in the formation of secondary mineral structures. We identified three groups of biological carbonates produced in vitro at 11°C on the basis of their carbon isotopic composition: carbonates with δ 13C values (a) slightly more positive, (b) more negative, and (c) much more negative than those of the stalactite carbonates. The carbonates belonging to the first group, characterized by the most similar δ 13C values to stalactites, were produced by the most abundant strains. Most of calcifying isolates belonged to the genus Kocuria. Scanning electron microscopy showed that dominant morphologies of the bioliths were sherulithic with fibrous radiated interiors. We suggest a mechanism of carbonate crystal formation by bacteria. 相似文献
5.
Fernando A. Villanea Deborah A. Bolnick Cara Monroe Rosita Worl Rosemary Cambra Alan Leventhal Brian M. Kemp 《American journal of physical anthropology》2013,151(4):649-657
In this study, we explore the geographic and temporal distribution of a unique variant of the O blood group allele called O1vG542A, which has been shown to be shared among Native Americans but is rare in other populations. O1vG542A was previously reported in Native American populations in Mesoamerica and South America, and has been proposed as an ancestry informative marker. We investigated whether this allele is also found in the Tlingit and Haida, two contemporary indigenous populations from Alaska, and a pre‐Columbian population from California. If O1vG542A is present in Na‐Dene speakers (i.e., Tlingits), it would indicate that Na‐Dene speaking groups share close ancestry with other Native American groups and support a Beringian origin of the allele, consistent with the Beringian Incubation Model. If O1vG542A is found in pre‐Columbian populations, it would further support a Beringian origin of the allele, rather than a more recent introduction of the allele into the Americas via gene flow from one or more populations which have admixed with Native Americans over the past five centuries. We identified this allele in one Na‐Dene population at a frequency of 0.11, and one ancient California population at a frequency of 0.20. Our results support a Beringian origin of O1vG542A, which is distributed today among all Native American groups that have been genotyped in appreciable numbers at this locus. This result is consistent with the hypothesis that Na‐Dene and other Native American populations primarily derive their ancestry from a single source population. Am J Phys Anthropol 151:649–657, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
6.
Liu P Sudhaharan T Koh RM Hwang LC Ahmed S Maruyama IN Wohland T 《Biophysical journal》2007,93(2):684-698
Single wavelength fluorescence cross-correlation spectroscopy (SW-FCCS), introduced to study biomolecular interactions, has recently been reported to monitor enzyme activity by using a newly developed fluorescent protein variant together with cyan fluorescent protein. Here, for the first time to our knowledge, SW-FCCS is applied to detect interactions between membrane receptors in vivo by using the widely used enhanced green fluorescent protein and monomeric red fluorescent protein. The biological system studied here is the epidermal growth factor/ErbB receptor family, which plays pivotal roles in the development of organisms ranging from worms to humans. It is widely thought that a ligand binds to the monomeric form of the receptor and induces its dimeric form for activation. By using SW-FCCS and F?rster resonance energy transfer, we show that the epidermal growth factor receptor and ErbB2 have preformed homo- and heterodimeric structures on the cell surface and quantitation of dimer fractions is performed by SW-FCCS. These receptors are major targets of anti-cancer drug development, and the receptors' homo- and heterodimeric structures are relevant for such developments. 相似文献
7.
Oxidative damage in rat erythrocyte membranes following ethanol intake: effect of ethyl pyruvate 总被引:1,自引:0,他引:1
Gabbianelli R Cifani C Massi M Polidori C Falcioni G 《Chemico-biological interactions》2007,169(2):122-131
Alcoholic patients and experimental animals exposed to ethanol display biochemical signs of oxidative damage, suggesting a possible role of free radicals in causing some of the toxic effects of alcohol. The ester derivative, ethyl pyruvate (EP) is stable in solution and should function as an antioxidant and energy precursor. In the present study, the effect of ethanol intake on plasma membrane fluidity, lipid oxidation and antioxidant enzyme activities (GPx, CAT and SOD) were first evaluated. Secondly, the consequences of ethyl pyruvate treatment on the physico-chemical properties of erythrocyte plasma membranes were investigated. The results obtained demonstrate that ethanol induces an increase in lipid peroxidation, a reduction of GPx activity and fluidity in the hydrophilic-hydrophobic region of the bilayer, moreover an increase of fluidity in hydrophobic part of the plasma membrane was measured. When rats were treated with ethyl pyruvate a partially protective effect can be observed for the hydrophilic-hydrophobic region tested by Laurdan, while EP cannot restore the DPH anisotropy values to the control values. In summary, our data indicate that treatment with EP can only partially reduce ethanol plasma membrane perturbation. Since this study shows an ethyl pyruvate dose-dependent effect, it is important to consider the amount of EP required to maintain the right level of membrane fluidity and polarity. These results could be interesting in order to investigate if EP, due to its radical scavenging effect, can prevent oxidative damage induced by ethanol intake and can protect against injure related with ethanol intake. 相似文献
8.
Jessica Perugini Laura Bordoni Wiebe Venema Samantha Acciarini Saverio Cinti Rosita Gabbianelli Antonio Giordano 《Journal of cellular physiology》2019,234(3):2031-2036
In the mammalian adipose organ cold exposure not only activates typical brown adipose tissue, but also induces browning, that is the formation of thermogenic multilocular adipocytes in white, or predominantly white, adipose depots such as subcutaneous fat. Unlike typical brown adipocytes, newly formed thermogenic adipocytes have been reported not to express the gene zinc finger of the cerebellum 1 (Zic1). Here, a time course approach enabled us to document a significant increase in Zic1 messenger RNA in inguinal subcutaneous fat from acutely (24 hr) cold-exposed mice, which was paralleled by an increase in multilocular and paucilocular uncoupling protein 1-positive adipocytes and in parenchymal noradrenergic innervation. This transient, depot-specific molecular signature was associated not to Zic1 promoter demethylation, but to chromatin remodeling through an H3K9me3 histone modification. These findings challenge the notion that Zic1 is exclusively expressed by typical brown adipocytes and suggest its involvement in brown adipocyte precursor differentiation and/or white-to-brown adipocyte transdifferentiation. 相似文献
9.
Ivarsson R Obermüller S Rutter GA Galvanovskis J Renström E 《Traffic (Copenhagen, Denmark)》2004,5(10):750-762
Glucose-evoked insulin secretion exhibits a biphasic time course and is associated with accelerated intracellular granule movement. We combined live confocal imaging of EGFP-labelled insulin granules with capacitance measurements of exocytosis in clonal INS-1 cells to explore the relation between distinct random and directed modes of insulin granule movement, as well as exocytotic capacity. Reducing the temperature from 34 degrees C to 24 degrees C caused a dramatic 81% drop in the frequency of directed events, but reduced directed velocities by a mere 25%. The much stronger temperature sensitivity of the frequency of directed events (estimated energy of activation approximately 135 kJ/mol) than that of the granule velocities (approximately 22 kJ/mol) suggests that cooling-induced suppression of insulin granule movement is attributable to factors other than reduced motor protein adenosine 5'-triphosphatase activity. Indeed, cooling suppresses random granule diffusion by approximately 50%. In the single cell, the number of directed events depends on the extent of granule diffusion. Finally, single-cell exocytosis exhibits a biphasic pattern corresponding to that observed in vivo, and only the component reflecting 2nd phase insulin secretion is affected by cooling. We conclude that random diffusive movement is a prerequisite for directed insulin granule transport and for the recruitment of insulin granules released during 2nd phase insulin secretion. 相似文献
10.
Gabbianelli R D'Orazio M Pacello F O'Neill P Nicolini L Rotilio G Battistoni A 《Biological chemistry》2004,385(8):749-754
Bacterial and eukaryotic Cu,Zn superoxide dismutases show remarkable differences in the active site region and in their quaternary structure organization. We report here a functional comparison between four Cu,Zn superoxide dismutases from Gram-negative bacteria and the eukaryotic bovine enzyme. Our data indicate that bacterial dimeric variants are characterized by catalytic rates higher than that of the bovine enzyme, probably due to the solvent accessibility of their active site. Prokaryotic Cu,Zn superoxide dismutases also show higher resistance to hydrogen peroxide inactivation and lower HCO3- -dependent peroxidative activity. Moreover, unlike the eukaryotic enzyme, all bacterial variants are susceptible to inactivation by chelating agents and show variable sensitivity to proteolytic attack, with the E. coli monomeric enzyme showing higher rates of inactivation by EDTA and proteinase K. We suggest that differences between individual bacterial variants could be due to the influence of modifications at the dimer interface on the enzyme conformational flexibility. 相似文献