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71.
Derepressed Hyphal Growth and Reduced Virulence in a VH1
Family-related Protein Phosphatase Mutant of the Human Pathogen
Candida albicans 总被引:3,自引:0,他引:3 下载免费PDF全文
Csilla Csank Constantin Makris Sylvain Meloche Klaus Schrppel Martin Rllinghoff Daniel Dignard David
Y. Thomas Malcolm Whiteway 《Molecular biology of the cell》1997,8(12):2539-2551
Mitogen-activated protein (MAP) kinases are pivotal components of eukaryotic signaling cascades. Phosphorylation of tyrosine and threonine residues activates MAP kinases, but either dual-specificity or monospecificity phosphatases can inactivate them. The Candida albicans CPP1 gene, a structural member of the VH1 family of dual- specificity phosphatases, was previously cloned by its ability to block the pheromone response MAP kinase cascade in Saccharomyces cerevisiae. Cpp1p inactivated mammalian MAP kinases in vitro and acted as a tyrosine-specific enzyme. In C. albicans a MAP kinase cascade can trigger the transition from the budding yeast form to a more invasive filamentous form. Disruption of the CPP1 gene in C. albicans derepressed the yeast to hyphal transition at ambient temperatures, on solid surfaces. A hyphal growth rate defect under physiological conditions in vitro was also observed and could explain a reduction in virulence associated with reduced fungal burden in the kidneys seen in a systemic mouse model. A hyper-hyphal pathway may thus have some detrimental effects on C. albicans cells. Disruption of the MAP kinase homologue CEK1 suppressed the morphological effects of the CPP1 disruption in C. albicans. The results presented here demonstrate the biological importance of a tyrosine phosphatase in cell-fate decisions and virulence in C. albicans. 相似文献
72.
Pacher Pal Kecskemeti Valeria Ronai Andras Z. Balogh Istvan Gabor Gabor Matkovics Bela 《Molecular and cellular biochemistry》1998,187(1-2):183-190
Human placental syncytiotrophoblast basal membrane plays an important role in transfer of nutrients from the mother to the growing fetus all throughout gestation. The membrane lipid composition together with the bilayer fluidity is found to be the major index in modulation of these transport processes. In the present study, the effects of changing lipid composition on the placental basal membrane fluidity and the modulating influence of the latter on membrane enzyme and transport functions with progress of gestation,were investigated. Steady-state fluorescence analysis using 1,6-diphenyl-1,3,5 hexatriene as the probe, indicated a decrease in fluorescence anisotropy of both labeled native membrane vesicles and liposomes prepared from lipids extracted from the basal membrane vesicles, signifying increased bilayer fluidity with progress of gestation. This in turn, was successfully correlated to the lowering of cholesterol content and enhanced phospholipid concentration with a steady decrease in cholesterol/phospholipid ratio during placental development. Enhanced Na+-K+-ATPase activity and steady-state glucose uptake across basal membrane with gestational progress suggested modulation of membrane protein functions by the fluidity, which was further corroborated by the increased bilayer fluidity and enzyme activity in benzyl alcohol treated basal membrane in each gestational age group. 相似文献
73.
Adam M. Nagy Rebeka Fekete Gergo Horvath Gabor Koncsos Csilla Kriston Anna Sebestyen Zoltan Giricz Zsuzsanna Kornyei Emilia Madarasz Laszlo Tretter 《BBA》2018,1859(3):201-214
Microglia are highly dynamic cells in the brain. Their functional diversity and phenotypic versatility brought microglial energy metabolism into the focus of research. Although it is known that microenvironmental cues shape microglial phenotype, their bioenergetic response to local nutrient availability remains unclear.In the present study effects of energy substrates on the oxidative and glycolytic metabolism of primary – and BV-2 microglial cells were investigated. Cellular oxygen consumption, glycolytic activity, the levels of intracellular ATP/ADP, autophagy, mTOR phosphorylation, apoptosis and cell viability were measured in the absence of nutrients or in the presence of physiological energy substrates: glutamine, glucose, lactate, pyruvate or ketone bodies.All of the oxidative energy metabolites increased the rate of basal and maximal respiration. However, the addition of glucose decreased microglial oxidative metabolism and glycolytic activity was enhanced. Increased ATP/ADP ratio and cell viability, activation of the mTOR and reduction of autophagic activity were observed in glutamine-supplemented media. Moreover, moderate and transient oxidation of ketone bodies was highly enhanced by glutamine, suggesting that anaplerosis of the TCA-cycle could stimulate ketone body oxidation.It is concluded that microglia show high metabolic plasticity and utilize a wide range of substrates. Among them glutamine is the most efficient metabolite. To our knowledge these data provide the first account of microglial direct metabolic response to nutrients under short-term starvation and demonstrate that microglia exhibit versatile metabolic machinery. Our finding that microglia have a distinct bioenergetic profile provides a critical foundation for specifying microglial contributions to brain energy metabolism. 相似文献
74.
Elaborate cognitive skills arose independently in different taxonomic groups. Self-recognition is conventionally identified by the understanding that one’s own mirror reflection does not represent another individual but oneself, which has never been proven in any elasmobranch species to date. Manta rays have a high encephalization quotient, similar to those species that have passed the mirror self-recognition test, and possess the largest brain of all fish species. In this study, mirror exposure experiments were conducted on two captive giant manta rays to document their response to their mirror image. The manta rays did not show signs of social interaction with their mirror image. However, frequent unusual and repetitive movements in front of the mirror suggested contingency checking; in addition, unusual self-directed behaviors could be identified when the manta rays were exposed to the mirror. The present study shows evidence for behavioral responses to a mirror that are prerequisite of self-awareness and which has been used to confirm self-recognition in apes. 相似文献
75.
Ari C Kálmán M 《Journal of experimental zoology. Part B. Molecular and developmental evolution》2008,310(6):504-519
This article presents the first study on the glial architecture of a representative species of Holocephali, Callorhinchus milii (ghost shark). Holocephali are a small subclass of Chondrichthyes, with only a few extant genera, and those are considered to have a brain organization more similar to squalomorph sharks than to galeomorph sharks, skates, and rays. Three different astroglial markers--glial fibrillary acidic protein, S-100 protein, and glutamine synthetase (GS)--were investigated by immunohistochemical methods, applying both diaminobenzidine (DAB) and fluorescent techniques. They revealed similar glial structures, although most of them were detected by immunohistochemical reaction against GS and visualized by DAB. The predominant elements were radial ependymoglia spanning the area between the ventricular and meningeal surfaces, as in squalomorph sharks. Other similar features were the light appearance of myelinated neural tracts devoid of immunoreactivity, and the glial architecture of the reticular formation of the brain stem, cerebellum, and tectum, the latter with recognizable layers. The immunoreactivity of the vascular walls was similar; however, it is believed that different cell types form the blood-brain barrier in chimeras and in elasmobranchs. Some glial structures, however, resembled those of skates, rays, and galeomorph sharks. In C. milii astrocyte-like elements were observed in the telencephalon, using GS and S-100, although typical astrocyte-rich regions were not found. In some areas, especially the telencephalon, not only endfeet but also cell bodies were observed to be attached to the meningeal surface, with processes extending into the brain substance. 相似文献
76.
During the extremely dry period between 2000 and 2003, the water level of Lake Balaton decreased by 82 cm and 80% of the stony littoral, an important habitat for the zebra mussel (Dreissena polymorpha), became dry. A recovery period started in 2004 due to intense precipitation, which increased water levels in the lake. Seasonal and spatial variations of the relative abundance, population density, population structure and biomass of the zebra mussel and the relative abundance of the amphipod Chelicorophium curvispinum were monitored in the period of 2003–2005 at four different shoreline sections and in two different portions (on the bottom and near the surface portion of the rip-rap) of Lake Balaton. Along with these studies, a quantitative survey of mussel larvae found in the plankton and of the abundance of mussel feeding diving ducks were made. As a consequence of the water level fall, on the dried part of the stony littoral, numerous zebra mussel druses perished. Following the dry period in early 2004, the relative abundance of the mussel on the bottom stones was smaller than in 2003 and the bottom community was dominated by C. curvispinum. By the end of 2004 and during 2005, the water level returned to normal and the surfaces of the reinundated stones were conducive to the successful colonization of zebra mussels. Hence, they returned as the dominant fauna in 2005. The stones near the surface might provide a new substrate for the recruitment of zebra mussels, probably offering more suitable substrata for the settlement in 2005 than in 2003. Therefore, the new substrata available in 2005 may have encouraged better and more rapid zebra mussel colonization than before. Zebra mussels may be better competitors for new space than C. curvispinum. A minor change of water-level fluctuation in 2005 and the reduction in population size of the mussel feeding waterfowl could have contributed to the intensive spread of zebra mussel by 2005. 相似文献
77.
Increased serum heat-shock protein 70 levels reflect systemic inflammation, oxidative stress and hepatocellular injury in preeclampsia 总被引:1,自引:0,他引:1
Molvarec A Rigó J Lázár L Balogh K Makó V Cervenak L Mézes M Prohászka Z 《Cell stress & chaperones》2009,14(2):151-159
It has been previously reported that serum levels of 70-kDa heat-shock protein (Hsp70) are elevated in preeclampsia. The aim
of the present study was to examine whether increased serum Hsp70 levels are related to clinical characteristics and standard
laboratory parameters of preeclamptic patients, as well as to markers of inflammation (C-reactive protein), endothelial activation
(von Willebrand factor antigen) or endothelial injury (fibronectin), trophoblast debris (cell-free fetal DNA) and oxidative
stress (malondialdehyde). Sixty-seven preeclamptic patients and 70 normotensive, healthy pregnant women were involved in this
case-control study. Serum Hsp70 levels were measured with enzyme-linked immunosorbent assay (ELISA). Standard laboratory parameters
(clinical chemistry) and C-reactive protein (CRP) levels were determined by an autoanalyzer using the manufacturer’s kits.
Plasma von Willebrand factor antigen (VWF:Ag) levels were quantified by ELISA, and plasma fibronectin concentration by nephelometry.
The amount of cell-free fetal DNA in maternal plasma was determined by quantitative real-time polymerase chain reaction analysis
of the sex-determining region Y gene. Plasma malondialdehyde levels were measured by the thiobarbituric acid-based colorimetric
assay. Serum Hsp70 levels were increased in preeclampsia. Furthermore, serum levels of blood urea nitrogen, creatinine, bilirubin
and CRP, serum alanine aminotransferase and lactate dehydrogenase (LDH) activities, as well as plasma levels of VWF:Ag, fibronectin,
cell-free fetal DNA and malondialdehyde were also significantly higher in preeclamptic patients than in normotensive, healthy
pregnant women. In preeclamptic patients, serum Hsp70 levels showed significant correlations with serum CRP levels (Spearman
R = 0.32, p = 0.010), serum aspartate aminotransferase (R = 0.32, p = 0.008) and LDH activities (R = 0.50, p < 0.001), as well as with plasma malondialdehyde levels (R = 0.25, p = 0.043). However, there was no other relationship between serum Hsp70 levels and clinical characteristics (age, parity,
body mass index, blood pressure, gestational age, fetal birth weight) and laboratory parameters of preeclamptic patients,
including markers of endothelial activation or injury and trophoblast debris. In conclusion, increased serum Hsp70 levels
seem to reflect systemic inflammation, oxidative stress and hepatocellular injury in preeclampsia. Nevertheless, further studies
are required to determine whether circulating Hsp70 plays a causative role in the pathogenesis of the disease. 相似文献
78.
Attila Molvarec Zoltán Derzsy Judit Kocsis Tamás Bőze Bálint Nagy Krisztián Balogh Veronika Makó László Cervenak Miklós Mézes István Karádi Zoltán Prohászka János Rigó Jr 《Cell stress & chaperones》2009,14(5):491-498
It has been previously reported that circulating anti-heat-shock-protein (Hsp) antibody levels are elevated in cardiovascular
disorders. The aim of the present study was to determine circulating antihuman Hsp60, antimycobacterial Hsp65, and antihuman
Hsp70 antibody levels in healthy pregnant women and preeclamptic patients and to investigate their relationship to the clinical
characteristics of the study subjects, as well as to the markers of inflammation (C-reactive protein (CRP)), endothelial activation
(von Willebrand factor antigen), or endothelial injury (fibronectin), oxidative stress (malondialdehyde) and to serum Hsp70
levels. Ninety-three preeclamptic patients and 127 normotensive healthy pregnant women were involved in this case control
study. Serum anti-Hsp60, anti-Hsp65, anti-Hsp70, and Hsp70 levels were measured with enzyme-linked immunosorbent assay (ELISA).
Serum CRP levels were determined by an autoanalyzer using the manufacturer’s kit. Plasma von Willebrand factor antigen levels
were quantified by ELISA, while plasma fibronectin concentration by nephelometry. Plasma malondialdehyde levels were measured
by the thiobarbituric-acid-based colorimetric assay. For statistical analyses, nonparametric methods were applied. Anti-Hsp60,
anti-Hsp65, and anti-Hsp70 antibodies were detected in all of our serum samples. There were no significant differences in
serum anti-Hsp60, anti-Hsp65, and anti-Hsp70 antibody levels between the control and preeclamptic groups. Serum levels of
Hsp70 and CRP, as well as plasma levels of VWF antigen, fibronectin, and malondialdehyde, were significantly higher in preeclamptic
patients than in normotensive healthy pregnant women. Serum anti-Hsp60 antibody levels showed significant correlations with
serum anti-Hsp65 antibody levels both in the control and the preeclamptic groups (Spearman R = 0.55 and 0.59; p < 0.001, respectively). However, no other relationship was found between clinical features (maternal age, smoking status,
parity, body mass index, gestational age at blood draw, systolic and diastolic blood pressure, gestational age at delivery,
and fetal birth weight) and measured laboratory parameters of the study subjects and serum anti-Hsp antibody levels in either
study group. In conclusion, anti-Hsp60 and anti-Hsp70 antibodies as naturally occurring autoantibodies are present in the
peripheral circulation of healthy pregnant women. Nevertheless, humoral immunity against heat shock proteins was not associated
with preeclampsia. Further studies are warranted to explore the role of heat shock proteins and immune reactivity to them
in the immunobiology of normal pregnancy and preeclampsia. 相似文献
79.
The aim of this study was to evaluate a measuring technique for determining soil CO2 efflux from large soil samples having undisturbed structure under controlled laboratory conditions. Further objectives were
to use the developed measuring method for comparing soil CO2 efflux from samples, collected in three different soil management systems at various soil water content values. The experimental
technique was tested and optimised for timing of sampling by taking air samples after 1, 3 and 6 hours of incubation. Based
on the results, the incubation time was set to three hours. The CO2 efflux measured for different soil management systems was the highest in the no-till and the lowest in the ploughing treatment,
which was in accordance with measurements on accessible organic carbon for microbes. An increase in CO2 efflux with increasing soil water content was found in the studied soil water content range. Our results indicate that soil
respiration rates, measured directly after tillage operations, can highly differ from those measured long after. 相似文献
80.
In this study the possible effects of two predicted climate change scenarios on soil water regime of Hungarian Calcic Chernozem
soils has been investigated. Soil profiles classified as Calcic Chernozem — in total 49 — were selected from the MARTHA soil
physical database that incorporates soil data at national scale. These profiles were subdivided into three groups (sandy loam,
loam and clayey loam) in accordance with their mechanical composition. Soil water retention curves were scaled separately
for each of the three textural groups, using similar media scaling in order to represent the variability of soil hydrophysical
data with one parameter, the scaling factor (SF). Reference soil profiles were chosen according to the cumulative distribution
function of the scaling factor, six for each textural group. Daily downscaled meteorological data from A2 and B2 climate scenarios
of the Hadley Centre (2070–2100) and data from a reference period (RF, 1961–1990) were used in this study to characterize
different climatic situations. Nine representative years were selected in case of all the three scenarios, using the cumulative
probability function of the annual precipitation sum. Scenario analyses were performed, validating the SWAP soil water balance
simulation model for the 18 reference soil profiles and 27 representative years in order to evaluate the expected changes
in soil water regime under different from the present (RF) climatic conditions (A2 and B2 scenarios). Our results show that
the scaling factor could be used as a climate sensitivity indicator of soil water regime. The large climate sensitivity of
the majority of Chernozem soil subtypes water regime has been proven. 相似文献