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排序方式: 共有339条查询结果,搜索用时 15 毫秒
31.
The expression of alphavbeta6 fibronectin/tenascin receptor integrin is induced in malignant transformation of oral epithelium. In this study, we demonstrate the contribution of alphavbeta6 as well as other fibronectin receptor integrins in squamous cell carcinoma (SCC) cell adhesion and migration. Of 11 SCC cell lines isolated from the head and neck area, 8 (73%) expressed alphavbeta6 integrin on the cell surface. Three cell lines were chosen for further functional experiments: 1 with relatively high, 1 with moderate, and 1 with minimal surface expression of alphavbeta6 integrin. In addition to alphavbeta6, all 3 cell lines expressed alpha5beta1 and alphavbeta1 fibronectin receptor integrins. Function-blocking experiments with inhibitory anti-integrin antibodies showed that all these three integrins were functional in SCC cell spreading on fibronectin. Integrin alphavbeta6, however, was not used as a primary but as an alternative fibronectin receptor by SCC cells, as the inhibitory anti-beta6 integrin antibody alone had no effect on spreading. In migration, however, alphavbeta6, alpha5beta1, and alphavbeta1 integrins were all used in cooperation. The presence of alphavbeta1 integrin in SCC cells is a novel finding as is its contribution to SCC cell migration. When one or two of these three receptors were blocked, the cells demonstrated an adaptive ability to remain migratory using integrins that were not targeted by antibodies. Utilization of a combination of receptors of different affinities may be beneficial for SCC cell migration versatility. 相似文献
32.
Avian top predator and the landscape of fear: responses of mammalian mesopredators to risk imposed by the golden eagle 下载免费PDF全文
Mari S. Lyly Alexandre Villers Elina Koivisto Pekka Helle Tuomo Ollila Erkki Korpimäki 《Ecology and evolution》2015,5(2):503-514
Top predators may induce extensive cascading effects on lower trophic levels, for example, through intraguild predation (IGP). The impacts of both mammalian and avian top predators on species of the same class have been extensively studied, but the effects of the latter upon mammalian mesopredators are not yet as well known. We examined the impact of the predation risk imposed by a large avian predator, the golden eagle (Aquila chrysaetos, L.), on its potential mammalian mesopredator prey, the red fox (Vulpes vulpes, L.), and the pine marten (Martes martes, L.). The study combined 23 years of countrywide data from nesting records of eagles and wildlife track counts of mesopredators in Finland, northern Europe. The predation risk of the golden eagle was modeled as a function of territory density, density of fledglings produced, and distance to nearest active eagle territory, with the expectation that a high predation risk would reduce the abundances of smaller sized pine martens in particular. Red foxes appeared not to suffer from eagle predation, being in fact most numerous close to eagle nests and in areas with more eagle territories. This is likely due to similar prey preferences of the two predators and the larger size of foxes enabling them to escape eagle predation risk. Somewhat contrary to our prediction, the abundance of pine martens increased from low to intermediate territory density and at close proximity to eagle nests, possibly because of similar habitat preferences of martens and eagles. We found a slightly decreasing trend of marten abundance at high territory density, which could indicate that the response in marten populations is dependent on eagle density. However, more research is needed to better establish whether mesopredators are intimidated or predated by golden eagles, and whether such effects could in turn cascade to lower trophic levels, benefitting herbivorous species. 相似文献
33.
Annina Kelloniemi Zoltan Szabo Raisa Serpi Juha N?p?nkangas Pauli Ohukainen Olli Tenhunen Leena Kaikkonen Elina Koivisto Zsolt Bagyura Risto Kerkel? Margret Leosdottir Thomas Hedner Olle Melander Heikki Ruskoaho Jaana Rys? 《PloS one》2015,10(6)
The phosphatase and actin regulator 1 (PHACTR1) locus is a very commonly identified hit in genome-wide association studies investigating coronary artery disease and myocardial infarction (MI). However, the function of PHACTR1 in the heart is still unknown. We characterized the mechanisms regulating Phactr1 expression in the heart, used adenoviral gene delivery to investigate the effects of Phactr1 on cardiac function, and analyzed the relationship between MI associated PHACTR1 allele and cardiac function in human subjects. Phactr1 mRNA and protein levels were markedly reduced (60%, P<0.01 and 90%, P<0.001, respectively) at 1 day after MI in rats. When the direct myocardial effects of Phactr1 were studied, the skeletal α-actin to cardiac α-actin isoform ratio was significantly higher (1.5-fold, P<0.05) at 3 days but 40% lower (P<0.05) at 2 weeks after adenovirus-mediated Phactr1 gene delivery into the anterior wall of the left ventricle. Similarly, the skeletal α-actin to cardiac α-actin ratio was lower at 2 weeks in infarcted hearts overexpressing Phactr1. In cultured neonatal cardiac myocytes, adenovirus-mediated Phactr1 overexpression for 48 hours markedly increased the skeletal α-actin to cardiac α-actin ratio, this being associated with an enhanced DNA binding activity of serum response factor. Phactr1 overexpression exerted no major effects on the expression of other cardiac genes or LV structure and function in normal and infarcted hearts during 2 weeks’ follow-up period. In human subjects, MI associated PHACTR1 allele was not associated significantly with cardiac function (n = 1550). Phactr1 seems to regulate the skeletal to cardiac α-actin isoform ratio. 相似文献
34.
A Potamogeton hybrid recently discovered in Finland was proven to be a new taxon, which has a different parentage than the most similar P.×vepsicus (=P. natans×praelongus) described from Russia. Based on molecular and morphological investigation, the new hybrid was identified as P. alpinus×natans and is here described as P.×exilis nothosp. nov. The hybrid is known only from several nearby localities in a single river system. All discovered colonies almost certainly originate from a single hybridization event that occurred in the upper part of the river system. Other localities downstream have been established through fragmentation and dispersal of stems and rhizomes of this sterile hybrid. A detailed morphological comparison of the new hybrid with similar hybrids and species is provided. 相似文献
35.
Badeau M Adlercreutz H Kaihovaara P Tikkanen MJ 《The Journal of steroid biochemistry and molecular biology》2005,96(3-4):271-278
The oxidative modification of lipoprotein particles is an important step in atherogenesis. Estrogens are known to be powerful antioxidants independently of their binding to the estrogen receptors and the hormonal functions. We explored the structural determinants for the antioxidant activity of a large number of estrogen derivatives (n=43) in an aqueous lipoprotein solution in vitro by monitoring formation of conjugated dienes. Our results indicate that estrogen derivatives with an unsubstituted A-ring phenolic hydroxyl group with one or two adjacent methoxy groups provide strongest antioxidant protection of low density lipoprotein (LDL) and high density lipoprotein (HDL). The electron donating methoxy groups may enhance the antioxidant effect by weakening the phenolic OH bond and providing stability to the formed phenoxyl radical. With some exceptions, compounds completely lacking unsubstituted hydroxyl groups in the A-ring exhibited no antioxidant effect, e.g. the most hydrophilic "tetrol" compound with three unsubstituted A-ring hydroxyl groups had no antioxidant effect. Moreover, additional hydroxyl groups in the B-, C- or D-ring seemed to weaken the antioxidant effect. Accordingly, both the presence of unsubstituted hydroxyl groups and adjacent substituents, as well as the lipophilicity of the derivatives determine the antioxidant activity of estrogen derivatives in aqueous lipoprotein solutions. 相似文献
36.
Wang H Lehtonen S Chen YC Heikkilä E Panula P Holthöfer H 《Differentiation; research in biological diversity》2012,83(1):38-46
Neph3 (filtrin) is a membrane protein expressed in the glomerular epithelial cells (podocytes), but its role in the glomerulus is still largely unknown. To characterize the function of Neph3 in the glomerulus, we employed the zebrafish as a model system. Here we show that the expression of neph3 in pronephros starts before the onset of nephrin and podocin expression, peaks when the nephron primordium differentiates into glomerulus and tubulus, and is then downregulated upon glomerular maturation. By histology, we found that neph3 is specifically expressed in pronephric podocytes at 36 hpf. Furthermore, disruption of neph3 expression by antisense morpholino oligonucleotides results in distorted body curvature and transient pericardial edema, the latter likely reflecting perturbation of glomerular osmoregulatory function. Histological analysis of neph3 morphants reveals altered glomerular morphology and dilated pronephric tubules. The phenotype of neph3 morphants, curved body and pericardial edema, is rescued by wild-type zebrafish neph3 mRNA. In addition to glomerulus, neph3 is highly expressed in the developing brain and specific regions of mature midbrain and hindbrain. In line with this, neph3 morphants show aberrant brain morphology. Collectively, the expression of neph3 in glomerulus and brain together with the morphant phenotype imply that neph3 is a pleiotropic gene active during distinct stages of tissue differentiation and associates directly in the regulation of both glomerular and neural development. 相似文献
37.
Carbon fluxes from a tropical peat swamp forest floor 总被引:3,自引:0,他引:3
Jyrki Jauhiainen Hidenori Takahashi† Juha E. P. Heikkinen‡ Pertti J. Martikainen‡ Harri Vasander§ 《Global Change Biology》2005,11(10):1788-1797
A tropical ombrotrophic peatland ecosystem is one of the largest terrestrial carbon stores. Flux rates of carbon dioxide (CO2) and methane (CH4) were studied at various peat water table depths in a mixed‐type peat swamp forest floor in Central Kalimantan, Indonesia. Temporary gas fluxes on microtopographically differing hummock and hollow peat surfaces were combined with peat water table data to produce annual cumulative flux estimates. Hummocks formed mainly from living and dead tree roots and decaying debris maintained a relatively steady CO2 emission rate regardless of the water table position in peat. In nearly vegetation‐free hollows, CO2 emission rates were progressively smaller as the water table rose towards the peat surface. Methane emissions from the peat surface remained small and were detected only in water‐saturated peat. By applying long‐term peat water table data, annual gas emissions from the peat swamp forest floor were estimated to be 3493±316 g CO2 m?2 and less than 1.36±0.57 g CH4 m?2. On the basis of the carbon emitted, CO2 is clearly a more important greenhouse gas than CH4. CO2 emissions from peat are the highest during the dry season, when the oxic peat layer is at its thickest because of water table lowering. 相似文献
38.
Effect of experimental nitrogen load on methane and nitrous oxide fluxes on ombrotrophic boreal peatland 总被引:8,自引:0,他引:8
Nykänen Hannu Vasander Harri Huttunen Jari T. Martikainen Pertti J. 《Plant and Soil》2002,242(1):147-155
Methane (CH4) and nitrous oxide (N2O) dynamics were studied in a boreal Sphagnum fuscum pine bog receiving annually (from 1991 to 1996) 30 or 100 kg NH4NO3-N ha–1. The gas emissions were measured during the last three growing seasons of the experiment. Nitrogen treatment did not affect the CH4 fluxes in the microsites where S. fuscum and S. angustifolium dominated. However, addition of 100 kg NH4NO3-N ha–1 yr–1 increased the CH4 emission from those microsites dominated by S. fuscum. This increase was associated with the increase in coverage of cotton grass (Eriophorum vaginatum) induced by the nitrogen treatment. The differences in the CH4 emissions were not related to the CH4 oxidation and production potentials in the peat profiles. The N2O fluxes were negligible from all microsites. Only minor short-term increases occurred after the nitrogen addition. 相似文献
39.
Pertti J. Pelto 《American anthropologist》1966,68(1):198-202
40.
Tuija Lauteala Pertti Sistonen Marja-Liisa Savontaus Juha Mykkänen Jaakko Simell Mari Lukkarinen Olli Simell Pertti Aula 《American journal of human genetics》1997,60(6):1479-1486
Lysinuric protein intolerance (LPI) is an autosomal recessive disease characterized by defective transport of cationic amino acids and by hyperammonemia. Linkage analysis in 20 Finnish LPI families assigned the LPI gene locus to the proximal long arm of chromosome 14. Recombinations placed the locus between framework markers D14S72 and MYH7, a 10-cM interval in which the markers D14S742, D14S50, D14S283, and TCRA showed no recombinations with the phenotype. The phenotype was in highly significant linkage disequilibrium with markers D14S50, D14S283, and TCRA. The strongest allelic association obtained with marker TCRA, resulting in a P(excess) value of .98, suggests that the LPI gene locus lies in close proximity to this marker, probably within a distance of < 100 kb. 相似文献