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991.
Jeffrey A. Simmons 《Water, air, and soil pollution》2010,209(1-4):123-132
Acid mine drainage (AMD) affects thousands of stream miles in the Appalachian region of the USA and results in elevated concentrations of iron and aluminum in the stream water and sediments and wide ranging pH values. It was hypothesized that these conditions would lead to increased P buffering capacity of the sediments which in turn would cause a decrease in dissolved reactive phosphorus (DRP) in the water column. In the lab fresh Fe, Al, and Mn oxide precipitates all adsorbed DRP strongly but over different pH ranges. Sulfate and calcium ions inhibited adsorption of DRP with Fe oxides but the effect was less apparent with Al oxides. In the field DRP concentration was reduced 54–90% just downstream of an AMD input compared to upstream of the input. In addition the sediment buffering capacity increased and equilibrium phosphate concentration decreased dramatically downstream of the AMD inputs. The strength of the effect and the widespread occurrence of AMD suggest that AMD could be altering the P dynamics of streams and rivers throughout the Appalachian region. 相似文献
992.
Anderson AC Anderson DE Bregoli L Hastings WD Kassam N Lei C Chandwaskar R Karman J Su EW Hirashima M Bruce JN Kane LP Kuchroo VK Hafler DA 《Science (New York, N.Y.)》2007,318(5853):1141-1143
CD4+ T helper 1 (TH1) cells are important mediators of inflammation and are regulated by numerous pathways, including the negative immune receptor Tim-3. We found that Tim-3 is constitutively expressed on cells of the innate immune system in both mice and humans, and that it can synergize with Toll-like receptors. Moreover, an antibody agonist of Tim-3 acted as an adjuvant during induced immune responses, and Tim-3 ligation induced distinct signaling events in T cells and dendritic cells; the latter finding could explain the apparent divergent functions of Tim-3 in these cell types. Thus, by virtue of differential expression on innate versus adaptive immune cells, Tim-3 can either promote or terminate TH1 immunity and may be able to influence a range of inflammatory conditions. 相似文献
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995.
Regulation of the polarity protein Par6 by TGFbeta receptors controls epithelial cell plasticity 总被引:1,自引:0,他引:1
Ozdamar B Bose R Barrios-Rodiles M Wang HR Zhang Y Wrana JL 《Science (New York, N.Y.)》2005,307(5715):1603-1609
The transition of cells from an epithelial to a mesenchymal phenotype is a critical event during morphogenesis in multicellular organisms and underlies the pathology of many diseases, including the invasive phenotype associated with metastatic carcinomas. Transforming growth factor beta (TGFbeta) is a key regulator of epithelial-to-mesenchymal transition (EMT). However, the molecular mechanisms that control the dissolution of tight junctions, an early event in EMT, remain elusive. We demonstrate that Par6, a regulator of epithelial cell polarity and tight-junction assembly, interacts with TGFbeta receptors and is a substrate of the type II receptor, TbetaRII. Phosphorylation of Par6 is required for TGFbeta-dependent EMT in mammary gland epithelial cells and controls the interaction of Par6 with the E3 ubiquitin ligase Smurf1. Smurf1, in turn, targets the guanosine triphosphatase RhoA for degradation, thereby leading to a loss of tight junctions. These studies define how an extracellular cue signals to the polarity machinery to control epithelial cell morphology. 相似文献
996.
Costadinos C. Mylonas Craig V. Sullivan Jeffrey M. Hinshaw 《Fish physiology and biochemistry》1994,13(6):485-493
Gravid brown trout (Salmo trutta) females were injected with various doses of a synthetic gonadotropin-releasing hormone analog (GnRHa), given with or without
an injection of triiodothyronine (T3), in order to investigate the potential of T3 (a) to enhance the stimulatory effect of GnRHa on ovulation, and (b) to enhance the growth and survival of the produced progeny.
From the time the hormonal treatments were initiated until ovulation was detected 5–38 days later, endogenous plasma T3 levels increased from an average of 3.6 to 11.6 ng ml−1. Injection with 20 mg T3 kg−1 body weight, further elevated plasma T3 levels at ovulation (16.0 ng ml−1. Mean time to ovulation was reduced significantly in fish injected with 10 μg kg−1 of GnRHa, whereas treatment with lower doses was ineffective. Injection with T3 did not enhance the ovulatory response of brown trout to GnRHa. Unfertilized eggs obtained from T3-injected females had a higher T3 content, suggesting a transfer of T3 from the maternal circulation into the oocytes. Maternal T3 injection had no effect on egg fertilization rates, embryo survival to eyeing and hatching, or the prevalence of abnormal
larvae at the time of hatching. Length and weight gain of the progeny during yolk absorption was also not influenced by maternal
T3 treatment. At the completion of yolk-sac absorption, progeny from females injected with T3 had a higher prevalence of skeletal abnormalities than controls. The results suggest that in teleosts like brown trout, which
have high endogenous circulating T3 levels, treatment of females with T3 does not enhance responsiveness to GnRHa and it has the potential for deleterious effects on their offspring. 相似文献
997.
Several investigations have recently assessed the ability of some aquatic invertebrates to act as tools for avian influenza A virus (IAV) surveillance as well as their potential role(s) in IAV ecology. Because of this, as well as the high IAV seroprevalence rates noted in select mesocarnivores that commonly inhabit aquatic and semi‐aquatic habitats, we evaluated the effects that freshwater crayfish have on IAV in water at three dose levels and monitored for the presence of IAV in crayfish tissues (gill and green gland) and haemolymph at multiple time points. At relatively high, medium and low (approximately 104, 103 and 102 EID50/ml, respectively) doses, mesocosms containing crayfish (Orconectes sp.) had less detectable IAV RNA present when final water samples were assayed (9 days post‐contact [DPC]). In general, containers without crayfish present had nearly three‐fold greater quantities of viral RNA at 9 DPC. A varying number of RNA positive samples were detected for the three crayfish sample types collected. Gill tissue produced the largest number of positive non‐water samples (n = 26), with the highest quantities detected from crayfish sampled on 1 and 4 DPC (103.5 EID50 equivalent/ml). On a few occasions, gill (n = 8) and haemolymph samples (n = 1) produced higher quantities of viral RNA than their respective water samples or water samples collected 1–2 DPC earlier, but these differences were typically minor. Based upon water samples, statistical models indicated that the interaction of dose and crayfish exposure days explained most of the variation in these data. Future efforts should address if crayfish exposed to IAV‐laden water have the capacity to successfully transmit IAVs to mammals and birds which frequently prey upon them. 相似文献
998.
Cameron J. Whittaker Benjamin D. Reynolds Paul M. McCarthy Simon F. Taylor Derek Major Kelly A. Caruso Jeffrey Smith 《Veterinary ophthalmology》2020,23(5):899-904
A 3‐year‐old Thoroughbred filly presented to a referral equine hospital for surgical correction of a severe cicatricial lateral lower eyelid ectropion OD, with secondary exposure keratitis. The severity of the ectropion deemed that conventional ectropion repairs would be unsuccessful. Therefore, a soft tissue expansion device was used to create sufficient local tissue for a rotational graft with tension‐relieving horizontal incisions to be performed to facilitate closure and acceptable eyelid apposition. The keratitis had resolved by two months postoperatively. There were no long‐term complications and only mild recurrence of the keratitis observed 14‐years postoperatively. 相似文献
999.
Brian K. Flesner Gary W. Wood Pamela Gayheart-Walsten F. Lynn Sonderegger Carolyn J. Henry Deborah J. Tate Sandra M. Bechtel Lindsay L. Donnelly Gayle C. Johnson Dae Young Kim Tammie A. Wahaus Jeffrey N. Bryan Noe Reyes 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2020,34(5):2056-2067
1000.