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61.
Numerous activities require an individual to respond quickly to the correct stimulus. The provision of advance information allows response priming but heightened responses can cause errors (responding too early or reacting to the wrong stimulus). Thus, a balance is required between the online cognitive mechanisms (inhibitory and anticipatory) used to prepare and execute a motor response at the appropriate time. We investigated the use of advance information in 71 participants across four different age groups: (i) children, (ii) young adults, (iii) middle-aged adults, and (iv) older adults. We implemented ‘cued’ and ‘non-cued’ conditions to assess age-related changes in saccadic and touch responses to targets in three movement conditions: (a) Eyes only; (b) Hands only; (c) Eyes and Hand. Children made less saccade errors compared to young adults, but they also exhibited longer response times in cued versus non-cued conditions. In contrast, older adults showed faster responses in cued conditions but exhibited more errors. The results indicate that young adults (18–25 years) achieve an optimal balance between anticipation and execution. In contrast, children show benefits (few errors) and costs (slow responses) of good inhibition when preparing a motor response based on advance information; whilst older adults show the benefits and costs associated with a prospective response strategy (i.e., good anticipation). 相似文献
62.
Anu Jose Mattam James M. Clomburg Ramon Gonzalez Syed Shams Yazdani 《Biotechnology letters》2013,35(6):831-842
Glycerol has attracted the attention of scientific and industrial communities due to its generation in bulk quantities as a byproduct of biofuel industries. With the rapid growth of these industries in recent years, glycerol is frequently treated as a very low-value byproduct or even a waste product with a disposal cost associated to it. Glycerol is not only abundant and inexpensive but also can generate more reducing equivalents than glucose or xylose. This unique characteristic of glycerol offers a tremendous opportunity for its biological conversion to valuable products at higher yield. This review focuses on research efforts to utilize glycerol as a carbon source for the production of a variety of fuels and chemicals by both native and metabolically engineered microorganisms. 相似文献
63.
Foster NL Paris CB Kool JT Baums IB Stevens JR Sanchez JA Bastidas C Agudelo C Bush P Day O Ferrari R Gonzalez P Gore S Guppy R McCartney MA McCoy C Mendes J Srinivasan A Steiner S Vermeij MJ Weil E Mumby PJ 《Molecular ecology》2012,21(5):1143-1157
Understanding patterns of connectivity among populations of marine organisms is essential for the development of realistic, spatially explicit models of population dynamics. Two approaches, empirical genetic patterns and oceanographic dispersal modelling, have been used to estimate levels of evolutionary connectivity among marine populations but rarely have their potentially complementary insights been combined. Here, a spatially realistic Lagrangian model of larval dispersal and a theoretical genetic model are integrated with the most extensive study of gene flow in a Caribbean marine organism. The 871 genets collected from 26 sites spread over the wider Caribbean subsampled 45.8% of the 1900 potential unique genets in the model. At a coarse scale, significant consensus between modelled estimates of genetic structure and empirical genetic data for populations of the reef-building coral Montastraea annularis is observed. However, modelled and empirical data differ in their estimates of connectivity among northern Mesoamerican reefs indicating that processes other than dispersal may dominate here. Further, the geographic location and porosity of the previously described east-west barrier to gene flow in the Caribbean is refined. A multi-prong approach, integrating genetic data and spatially realistic models of larval dispersal and genetic projection, provides complementary insights into the processes underpinning population connectivity in marine invertebrates on evolutionary timescales. 相似文献
64.
NADPH oxidase inhibition does not interfere with low PO2 transduction in rat and rabbit CB chemoreceptor cells 总被引:1,自引:0,他引:1
Obeso A.; Gomez-Nino A.; Gonzalez C. 《American journal of physiology. Cell physiology》1999,276(3):C593
The aim of the present work was to elucidate therole of NADPH oxidase in hypoxia sensing and transduction in thecarotid body (CB) chemoreceptor cells. We have studied the effects of several inhibitors of NADPH oxidase on the normoxic and hypoxia-induced release of [3H]catecholamines(CA) in an in vitro preparation of intact CB of the rat and rabbitwhose CA deposits have been labeled by prior incubation with thenatural precursor[3H]tyrosine. It wasfound that diphenyleneiodonium (DPI; 0.2-25 µM), an inhibitor ofNADPH oxidase, caused a dose-dependent release of[3H]CA from normoxic CBchemoreceptor cells. Contrary to hypoxia, DPI-evoked release was onlypartially Ca2+ dependent.Concentrations of DPI reported to produce full inhibition of NADPHoxidase in the rat CB did not prevent the hypoxic release response inthe rat and rabbit CB chemoreceptor cells, as stimulation with hypoxiain the presence of DPI elicited a response equaling the sum of thatproduced by DPI and hypoxia applied separately. Neopterin (3-300µM) and phenylarsine oxide (0.5-2 µM), other inhibitors ofNADPH oxidase, did not promote release of[3H]CA in normoxic conditions oraffect the response elicited by hypoxia. On the basis of effects ofneopterin and phenylarsine oxide, it is concluded that NADPH oxidasedoes not appear to play a role in oxygen sensing or transduction in therat and rabbit CB chemoreceptor cells in vitro and, in the context ofthe present study, that DPI effects are not related to NADPH oxidase inhibition. 相似文献
65.
J. L. Blanco L. Domínguez Esperanza Gómez-Lucía J. F. F. Garayzabal J. Goyache G. Suárez 《Journal of applied microbiology》1988,64(1):17-26
Manchego-type cheese, a typical Spanish cheese, was inoculated in various ways with an aflatoxigenic organism, Aspergillus parasiticus NRRL 2999, to study the production of aflatoxin. When the original milk was contaminated with a spore suspension, aflatoxin was not detected in paraffin-covered cheeses although it was present in the top layer of non-paraffin-covered cheeses after ripening at 15°C for 60 d. When the cheese surface was inoculated, no aflatoxins were detected in paraffin-covered cheeses after ripening for 60 d although they were found when the cheeses were ripened for 30 d. In non-paraffin-covered cheeses aflatoxins were detected only in the top layer and in the second 10 mm layer when cheeses were incubated after the normal ripening at 28°C for 30 d. When the centre of the cheese was inoculated, no aflatoxins were detected although Aspergillus grew slightly along the inoculation area. When cheese portions were inoculated, fungal growth was evident after incubation at 28° and 15°C for 6 d but there was no growth at 10°C after 50 d. At 28°C aflatoxins were detected at a concentration of 132 μg/g after 13 d, the highest level obtained. In cheese paste at 28° and 15°C, growth was intense, but the level of aflatoxins detected was lower than in cheese portions. At 10°C the growth was heavy, but aflatoxins were not detected. 相似文献
66.
Pharmacological Characterization of Somatostatin Receptors in the Rat Cerebellum During Development 总被引:3,自引:2,他引:3
Bruno J. Gonzalez Philippe Leroux Corinne Bodenant Pierre Braquet Hubert Vaudry 《Journal of neurochemistry》1990,55(3):729-737
Abstract: Somatostatin (SRIF) receptors (SRIF-Rs) are transiently expressed in a germinative lamina of the rat cerebellum, the external granule cell layer. The appearance of SRIF-Rs coincides with the expression of SRIF-like immunoreactivity in the cerebellum. However, the cellular location of SRIF-Rs does not overlap with the distribution of SRIF-like immunoreactivity, with the latter being restricted to ascending fibers arising from the brainstem, to perikarya within the white matter, and to some Purkinje cells. The characterization of SRIF-Rs in the immature (13–day-old) rat cerebellum was conducted by means of binding experiments in membraneenriched preparations and autoradiography, using two radioligands, [125I-Tyr0,D-Trp8]SRIF-14 ([125I-Tyr0,d -Trp8]S14) and I25I-SMS 204–090. The pharmacological profile of cerebellar SRIF-Rs was compared with that of adult cortical SRIF-Rs. Saturation studies performed in 13–day-old rat cerebellum showed that the A'D values for [125I-Tyr0,D-Trp8]S14 and 125I-SMS 204–090 binding were 0.35 ± 0.04 and 0.39 ± 0.01 nM, respectively. The corresponding Bmax values were 52.7 ± 4.8 and 49.9 ± 5.3 fmol/mg of protein, a result indicating that radioligands with high specific radioactivity (2,000 Ci/mmol) bind to a single class of high-affinity sites (SSI). Competition studies showed that different D-Trp-sub-stituted analogs displaced [125I-Tyr0,d -Trp8]S14 binding with Hill coefficients >1, a finding indicating the existence of different subtypes of binding sites. When [Tyr0,d -Trp8]S14 was used as a competitor, two sites were resolved by Scatchard analysis in both 13–day-old cerebellum and adult cerebral cortex. The higher-affinity sites correspond to the SSI subtype identified in saturation experiments, whereas the lower-affinity sites most likely correspond to the SS2 subtype. Ionic supplementation studies showed that divalent cations were required to obtain maximal specific binding on the SSI sites. In particular, Mn2+ was the most efficient cation for promoting binding of [125I-Tyr0,d -Trp8]S14. Addition of GTP to the incubation buffer induced a marked reduction of specific binding. The results obtained by membrane binding assays were similar to those obtained by quantitative autoradiography, a result indicating that the microenvironment of SRIF-Rs was preserved in both types of tissue preparations. Receptors expressed in the developing rat cerebellum exhibited the same KD and similar pharmacological profile as those observed in the adult rat cortex. These results show that SRIF-binding sites transiently expressed in the external granule cell layer of the cerebellum of young rats are indistinguishable from adult rat brain SRIF-Rs. The extremely high density of SRIF-Rs found in the external granule cell layer in 13–day-old rats suggests that SRIF may play a pivotal role in the proliferation and/or differentiation of these germinative cells. 相似文献
67.
Siegel G Sternfeld L Gonzalez A Schulz I Schmid A 《The Journal of biological chemistry》2001,276(20):16986-16991
In pancreatic acinar cells analysis of the propagation speed of secretagogue-evoked Ca2+ waves can be used to examine coupling of hormone receptors to intracellular signal cascades that cause activation of protein kinase C or production of arachidonic acid (AA). In the present study we have investigated the role of cytosolic phospholipase A2 (cPLA2) and AA in acetylcholine (ACh)- and bombesin-induced Ca2+ signaling. Inhibition of cPLA2 caused acceleration of ACh-induced Ca2+ waves, whereas bombesin-evoked Ca2+ waves were unaffected. When enzymatic metabolization of AA was prevented with the cyclooxygenase inhibitor indomethacin or the lipoxygenase inhibitor nordihydroguaiaretic acid, ACh-induced Ca2+ waves were slowed down. Agonist-induced activation of cPLA2 involves mitogen-activated protein kinase (MAPK) activation. An increase in phosphorylation of p38(MAPK) and p42/44(MAPK) within 10 s after stimulation could be demonstrated for ACh but was absent for bombesin. Rapid phosphorylation of p38(MAPK) and p42/44(MAPK) could also be observed in the presence of cholecystokinin (CCK), which also causes activation of cPLA2. ACh-and CCK-induced Ca2+ waves were slowed down when p38(MAPK) was inhibited with SB 203580, whereas inhibition of p42/44(MAPK) with PD 98059 caused acceleration of ACh- and CCK-induced Ca2+ waves. The spreading of bombesin-evoked Ca2+ waves was affected neither by PD 98059 nor by SB 203580. Our data indicate that in mouse pancreatic acinar cells both ACh and CCK receptors couple to the cPLA2 pathway. cPLA2 activation occurs within 1-2 s after hormone application and is promoted by p42/44(MAPK) and inhibited by p38(MAPK). Furthermore, the data demonstrate that secondary (Ca2+-induced) Ca2+ release, which supports Ca2+ wave spreading, is inhibited by AA itself and not by a metabolite of AA. 相似文献
68.
Summary Cellulolytic fungi were isolated from rotting leaves and tested for extra-cellular cellulase activities (CMCase, avicelase, cellobiase and xylanase). The effect of the proportion of the enzyme activities on the rate of degradation of leached beet cosette was observed using a range of supernatant fluids in appropriate combinations. At low cosette concentrations (1.5–3.0 g/l), avicelase and cellobiase were the rate limiting enzymes; avicelase in the initial stages of reaction and cellobiase after 6–8 hours, when cellobiose inhibition becomes important. A ratio of celiobiase to avicelase of approx 2.0 was established as appropriate. At higher substrate concentrations (10 g/l, 40 g/l) the best cellobiase to avicelase ratio was maintained and up to 40% hydrolysis was obtained in the 10 g/l incubation with 10 Uav/l and 20 Ucellob/l. At 100 g/l cosette concentration, substrate inhibition was observed. 相似文献
69.
Degradation of the Retinoblastoma Tumor Suppressor by the Human Papillomavirus Type 16 E7 Oncoprotein Is Important for Functional Inactivation and Is Separable from Proteasomal Degradation of E7 总被引:8,自引:0,他引:8 下载免费PDF全文
Sonia L. Gonzalez Matt Stremlau Xi He John R. Basile Karl Münger 《Journal of virology》2001,75(16):7583-7591
The steady-state level and metabolic half-life of retinoblastoma tumor suppressor protein pRB are decreased in cells that express high-risk human papillomavirus (HPV) E7 proteins. Here we show that pRB degradation is a direct activity of E7 and does not reflect a property of cell lines acquired during the selection process for E7 expression. An amino-terminal domain of E7 that does not directly contribute to pRB binding but is required for transformation is also necessary for E7-mediated pRB degradation. Treatment with inhibitors of the 26S proteasome not only blocks E7-mediated pRB degradation but also causes the stabilization of E7. Mutagenic analyses, however, reveal that the processes of proteasomal degradation of E7 and pRB are not linked processes. HPV type 16 E7 also targets the pRB-related proteins p107 and p130 for destabilization by a proteasome-dependent mechanism. Using the SAOS2 flat-cell assay as a biological indicator for pRB function, we demonstrate that pRB degradation, not solely binding, is important for the E7-induced inactivation of pRB. 相似文献
70.