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41.
We recently reported that bile salts play a role in the regulation of mucin
secretion by cultured dog gallbladder epithelial cells. In this study we
have examined whether bile salts also influence mucin secretion by the
human epithelial colon cell line LS174T. Solutions of bile salts were
applied to monolayers of LS174T cells. Mucin secretion was quantified by
measuring the secretion of [3H]GlcNAc labeled glycoproteins. Both
unconjugated bile salts as well as taurine conjugated bile salts stimulated
mucin secretion by the colon cells in a dose-dependent fashion. Hydrophobic
bile salts were more potent stimulators than hydrophilic bile salts. Free
(unconjugated) bile salts were more stimulatory compared with their taurine
conjugated counterparts. Stimulation of mucin secretion by LS174T cells was
found to occur at much lower bile salt concentrations than in the
experiments with the dog gallbladder epithelial cells. The protein kinase C
activators PMA and PDB had no stimulatory effect on mucin secretion. We
conclude that mucin secretion by the human colon epithelial cell line
LS174T is regulated by bile salts. We suggest that regulation of mucin
secretion by bile salts might be a common mechanism, by which different
epithelia protect themselves against the detergent action of bile salts, to
which they are exposed throughout the gastrointestinal tract.
相似文献
42.
Marcel GA van der Heijden Susanne de Bruin Ludo Luckerhoff Richard SP van Logtestijn Klaus Schlaeppi 《The ISME journal》2016,10(2):389-399
Highly diverse microbial assemblages colonize plant roots. It is still poorly understood whether different members of this root microbiome act synergistically by supplying different services (for example, different limiting nutrients) to plants and plant communities. In order to test this, we manipulated the presence of two widespread plant root symbionts, arbuscular mycorrhizal fungi and nitrogen-fixing rhizobia bacteria in model grassland communities established in axenic microcosms. Here, we demonstrate that both symbionts complement each other resulting in increased plant diversity, enhanced seedling recruitment and improved nutrient acquisition compared with a single symbiont situation. Legume seedlings obtained up to 15-fold higher productivity if they formed an association with both symbionts, opposed to productivity they reached with only one symbiont. Our results reveal the importance of functional diversity of symbionts and demonstrate that different members of the root microbiome can complement each other in acquiring different limiting nutrients and in driving important ecosystem functions. 相似文献
43.
Sodium balance determines the extracellular fluid volume and sets arterial blood pressure (BP). Chronically raised BP (hypertension)
represents a major health risk in Western societies. The relationship between BP and renal sodium excretion (the pressure/natriuresis
relationship) represents the key element in defining the BP homeostatic set point. The renin–angiotensin–aldosterone system
(RAAS) makes major adjustments to the rates of renal sodium secretion, but this system works slowly over a period of hours
to days. More rapid adjustments can be made by the sympathetic nervous system, although the kidney can function well without
sympathetic nerves. Attention has now focussed on regulatory mechanisms within the kidney, including extracellular nucleotides
and the P2 receptor system. Here, we discuss how extracellular ATP can control renal sodium excretion by altering the activity
of epithelial sodium channels (ENaC) present in the apical membrane of principal cells. There remains considerable controversy
over the molecular targets for released ATP, although the P2Y2 receptor has received much attention. We review the available data and reflect on our own findings in which ATP-activated
P2Y and P2X receptors make adjustments to ENaC activity and therefore sodium excretion. 相似文献
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47.
Sery Gonedelé Bi Didier P Sokouri Kouakou Tiékoura Oulo Alla N?Nan Marcel Lolo Félix Gnangbé Assanvo SP N?Guetta 《Bioinformation》2014,10(11):671-678
Cête d׳Ivoire continues to have the highest HIV-1 prevalence rate in West Africa, although the infection number is in constant decline. The external envelope protein of the viruses is a likely site of selection, and responsible for receptor binding and entry into host cells, and therefore constitutes an ideal region with which to investigate the evolutionary processes acting on HIV-1. In this study, we analyse 189 envelope glycoprotein V3 loop region sequences of viruse isolates from 1995 to 2009, from HIV-1 untreated patients living in Cête d׳Ivoire, to decipher the temporal relationship between disease diversity, divergence and selection. Our analyses show that the nonsynonymous and synonymous ratio (dN/dS) was lower than 1 for viral populations analysed within 15 years, which showed the sequences did not undergo adequate immune pressure. The phylogenetic tree of the sequences analysed demonstrated distinctly long internal branches and short external branches, suggesting that only a small number of viruses infected the new host cell at each transmission. In addition to identifying sites under purifying selection, we also identified neutral sites that can cause false positive inference of selection. These sites presented form a resource for future studies of selection pressures acting on HIV-1 enν gene in Cête d׳Ivoire and other West African countries. 相似文献
48.
DOMINIK LERMEN BRUNHILDE BLÖMEKE ROBERT BROWNE ANN CLARKE PAUL W. DYCE THOMAS FIXEMER GÜNTER R. FUHR WILLIAM V. HOLT KATARINA JEWGENOW RHIANNON E. LLOYD STEFAN LÖTTERS MARTIN PAULUS GORDON MCGREGOR REID DANIEL H. RAPOPORT DAVID RAWSON JENNIFER RINGLEB OLIVER A. RYDER GABRIELE SPÖRL THOMAS SCHMITT MICHAEL VEITH PAUL MÜLLER 《Molecular ecology》2009,18(6):1030-1033
Cryobanking, the freezing of biological specimens to maintain their integrity for a variety of anticipated and unanticipated uses, offers unique opportunities to advance the basic knowledge of biological systems and their evolution. Notably, cryobanking provides a crucial opportunity to support conservation efforts for endangered species. Historically, cryobanking has been developed mostly in response to human economic and medical needs — these needs must now be extended to biodiversity conservation. Reproduction technologies utilizing cryobanked gametes, embryos and somatic cells are already vital components of endangered species recovery efforts. Advances in modern biological research (e.g. stem cell research, genomics and proteomics) are already drawing heavily on cryobanked specimens, and future needs are anticipated to be immense. The challenges of developing and applying cryobanking for a broader diversity of species were addressed at an international conference held at Trier University (Germany) in June 2008. However, the magnitude of the potential benefits of cryobanking stood in stark contrast to the lack of substantial resources available for this area of strategic interest for biological science — and society at large. The meeting at Trier established a foundation for a strong global incentive to cryobank threatened species. The establishment of an Amphibian Ark cryobanking programme offers the first opportunity for global cooperation to achieve the cryobanking of the threatened species from an entire vertebrate class. 相似文献
49.
Oliver Beckstein Ekaterina Ivanova Tian Geng Simone Weyand David Drew Joseph Lanigan David J Sharples Mark SP Sansom So Iwata Colin WG Fishwick A Peter Johnson Alexander D Cameron Peter JF Henderson 《The EMBO journal》2014,33(16):1831-1844
The hydantoin transporter Mhp1 is a sodium‐coupled secondary active transport protein of the nucleobase‐cation‐symport family and a member of the widespread 5‐helix inverted repeat superfamily of transporters. The structure of Mhp1 was previously solved in three different conformations providing insight into the molecular basis of the alternating access mechanism. Here, we elucidate detailed events of substrate binding, through a combination of crystallography, molecular dynamics, site‐directed mutagenesis, biochemical/biophysical assays, and the design and synthesis of novel ligands. We show precisely where 5‐substituted hydantoin substrates bind in an extended configuration at the interface of the bundle and hash domains. They are recognised through hydrogen bonds to the hydantoin moiety and the complementarity of the 5‐substituent for a hydrophobic pocket in the protein. Furthermore, we describe a novel structure of an intermediate state of the protein with the external thin gate locked open by an inhibitor, 5‐(2‐naphthylmethyl)‐L‐hydantoin, which becomes a substrate when leucine 363 is changed to an alanine. We deduce the molecular events that underlie acquisition and transport of a ligand by Mhp1. 相似文献
50.
Alexandra R. Lucas Raj K. Verma Erbin Dai Liying Liu Hao Chen Sheela Kesavalu Mercedes Rivera Irina Velsko Sriram Ambadapadi Sasanka Chukkapalli Lakshmyya Kesavalu 《PloS one》2014,9(10)
Thrombotic occlusion of inflammatory plaque in coronary arteries causes myocardial infarction. Treatment with emergent balloon angioplasty (BA) and stent implant improves survival, but restenosis (regrowth) can occur. Periodontal bacteremia is closely associated with inflammation and native arterial atherosclerosis, with potential to increase restenosis. Two virus-derived anti-inflammatory proteins, M-T7 and Serp-1, reduce inflammation and plaque growth after BA and transplant in animal models through separate pathways. M-T7 is a broad spectrum C, CC and CXC chemokine-binding protein. Serp-1 is a serine protease inhibitor (serpin) inhibiting thrombotic and thrombolytic pathways. Serp-1 also reduces arterial inflammation and improves survival in a mouse herpes virus (MHV68) model of lethal vasculitis. In addition, Serp-1 demonstrated safety and efficacy in patients with unstable coronary disease and stent implant, reducing markers of myocardial damage. We investigate here the effects of Porphyromonas gingivalis, a periodontal pathogen, on restenosis after BA and the effects of blocking chemokine and protease pathways with M-T7 and Serp-1. ApoE−/− mice had aortic BA and oral P. gingivalis infection. Arterial plaque growth was examined at 24 weeks with and without anti-inflammatory protein treatment. Dental plaques from mice infected with P. gingivalis tested positive for infection. Neither Serp-1 nor M-T7 treatment reduced infection, but IgG antibody levels in mice treated with Serp-1 and M-T7 were reduced. P. gingivalis significantly increased monocyte invasion and arterial plaque growth after BA (P<0.025). Monocyte invasion and plaque growth were blocked by M-T7 treatment (P<0.023), whereas Serp-1 produced only a trend toward reductions. Both proteins modified expression of TLR4 and MyD88. In conclusion, aortic plaque growth in ApoE−/− mice increased after angioplasty in mice with chronic oral P. gingivalis infection. Blockade of chemokines, but not serine proteases significantly reduced arterial plaque growth, suggesting a central role for chemokine-mediated inflammation after BA in P. gingivalis infected mice. 相似文献