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1.
Heavy water (H218O) has been used to label DNA of soil microorganisms in stable isotope probing experiments, yet no measurements have been
reported for the 18O content of DNA from soil incubated with heavy water. Here we present the first measurements of atom% 18O for DNA extracted from soil incubated with the addition of H218O. Four experiments were conducted to test how the atom% 18O of DNA, extracted from Ponderosa Pine forest soil incubated with heavy water, was affected by the following variables: (1)
time, (2) nutrients, (3) soil moisture, and (4) atom% 18O of added H2O. In the time series experiment, the atom% 18O of DNA increased linearly (R
2 = 0.994, p < 0.01) over the first 72 h of incubation. In the nutrient addition experiment, there was a positive correlation (R
2 = 0.991, p = 0.006) between the log10 of the amount of tryptic soy broth, a complex nutrient broth, added to soil and the log10 of the atom% 18O of DNA. For the experiment where soil moisture was manipulated, the atom% 18O of DNA increased with higher soil moisture until soil moisture reached 30%, above which 18O enrichment of DNA declined as soils became more saturated. When the atom% 18O for H2O added was varied, there was a positive linear relationship between the atom% 18O of the added water and the atom% 18O of the DNA. Results indicate that quantification of 18O incorporated into DNA from H218O has potential to be used as a proxy for microbial growth in soil. 相似文献
2.
Ging Kuo Wang Joanna Calderon Shiow-Jiin Jaw Sho-Ya Wang 《The Journal of membrane biology》2009,229(1):1-9
Articaine is widely used as a local anesthetic (LA) in dentistry, but little is known regarding its blocking actions on Na+ channels. We therefore examined the state-dependent block of articaine first in rat skeletal muscle rNav1.4 Na+ channels expressed in Hek293t cells. Articaine exhibited a weak block of resting rNav1.4 Na+ channels at −140 mV with a 50% inhibitory concentration (IC50) of 378 ± 26 μM (n = 5). The affinity was higher for inactivated Na+ channels measured at −70 mV with an IC50 value of 40.6 ± 2.7 μM (n = 5). The open-channel block by articaine was measured using inactivation-deficient rNav1.4 Na+ channels with an IC50 value of 15.8 ± 1.5 μM (n = 5). Receptor mapping demonstrated that articaine interacted strongly with a D4S6 phenylalanine residue, which is known
to form a part of the LA receptor. Thus the block of rNav1.4 Na+ channels by articaine is via the conserved LA receptor in a highly state-dependent manner, with a ranking order of open (23.9×) > inactivated
(9.3×) > resting (1×) state. Finally, the open-channel block by articaine was likewise measured in inactivation-deficient
hNav1.7 and rNav1.8 Na+ channels, with IC50 values of 8.8 ± 0.1 and 22.0 ± 0.5 μM, respectively (n = 5), indicating that the high-affinity open-channel block by articaine is indeed preserved in neuronal Na+ channel isoforms. 相似文献
3.
Guenterberg KD Lesinski GB Mundy-Bosse BL Karpa VI Jaime-Ramirez AC Wei L Carson WE 《Cancer immunology, immunotherapy : CII》2011,60(9):1281-1288
Interferon-alpha (IFN-α) is an immunomodulatory cytokine that is used clinically for the treatment of melanoma in the adjuvant
setting. The cellular actions of IFN-α are regulated by the suppressors of cytokine signaling (SOCS) family of proteins. We
hypothesized that the anti-tumor activity of exogenous IFN-α would be enhanced in SOCS1-deficient mice. SOCS1-deficient (SOCS1−/−) or control (SOCS1+/+) mice on an IFN-γ−/− C57BL/6 background bearing intraperitoneal (i.p.) JB/MS murine melanoma cells were treated for 30 days with i.p. injections
of IFN-A/D or PBS (vehicle). Log-rank Kaplan-Meier survival curves were used to evaluate survival. Tumor-bearing control SOCS1+/+ mice receiving IFN-A/D had significantly enhanced survival versus PBS–treated mice (P = 0.0048). The anti-tumor effects of IFN-A/D therapy were significantly enhanced in tumor-bearing SOCS1−/− mice; 75% of these mice survived tumor challenge, whereas PBS-treated SOCS1−/− mice all died at 13-16 days (P = 0.00038). Antibody (Ab) depletion of CD8+ T cells abrogated the anti-tumor effects of IFN-A/D in SOCS1−/− mice as compared with mice receiving a control antibody (P = 0.0021). CD4+ T-cell depletion from SOCS1−/− mice also inhibited the effects of IFN-A/D (P = 0.0003). IFN-A/D did not alter expression of CD80 or CD86 on splenocytes of SOCS1+/+ or SOCS1−/− mice, or the proportion of T regulatory cells or myeloid-derived suppressor cells in SOCS1+/+ or SOCS1−/− mice. An analysis of T-cell function did reveal increased proliferation of SOCS1-deficient splenocytes at baseline and in
response to mitogenic stimuli. These data suggest that modulation of SOCS1 function in T-cell subsets could enhance the anti-tumor
effects of IFN-α in the setting of melanoma. 相似文献
4.
Liang Lu Changsong Wang Xiaohua Gao Peng Xu Jun Wang Qiang Wang Jie Cheng Hang Xiao 《The Journal of membrane biology》2009,227(2):87-94
Low voltage-activated, rapidly inactivating T-type Ca2+ channels are found in a variety of cells, where they regulate electrical activity and Ca2+ entry. In whole-cell patch-clamp recordings from mouse spermatogenic cells, trace element copper (Cu2+) inhibited T-type Ca2+ current (I
T-Ca) with IC50 of 12.06 μM. Inhibition of I
T-Ca by Cu2+ was concentration-dependent and mildly voltage-dependent. When voltage stepped to −20 mV, Cu2+ (10 μM) inhibited I
T-Ca by 49.6 ± 4.1%. Inhibition of I
T-Ca by Cu2+ was accompanied by a shift of −2.23 mV in the voltage dependence of steady-state inactivation. Cu2+ upshifted the current–voltage (I-V) curve. To know the change of the gating kinetics of T-type Ca2+ channels, we analyzed the effect of Cu2+ on activation, inactivation, deactivation and reactivation of T-type Ca2+ channels. Since T-type Ca2+ channels are a key component in capacitation and the acrosome reaction, our data suggest that Cu2+ can affect male reproductive function through T-type Ca2+ channels as a preconception contraceptive material. 相似文献
5.
Aporn Bualuang Kanteera Soontharapirakkul Aran Incharoensakdi 《Journal of applied phycology》2010,22(2):123-129
The activity of Na+/H+ exchanger to remove toxic Na+ is important for growth of organisms under high salinity. In this study, the halotolerant cyanobacterium Aphanothece halophytica was shown to possess Na+/H+ exchange activity since exogenously added Na+ could dissipate a pre-formed pH gradient, and decrease extracellular pH. Kinetic analysis yielded apparent K
m (Na+) and V
max of 20.7 ± 3.1 mM and 3,333 ± 370 nmol H+ min−1 mg−1, respectively. For cells grown under salt-stress condition, the apparent K
m (Na+) and V
max was 18.3 ± 3.5 mM and 3,703 ± 350 nmol H+ min−1 mg−1, respectively. Three cations with decreasing efficiency namely Li+, Ca2+, and K+ were also able to dissipate pH gradient. Only marginal exchange activity was observed for Mg2+. The exchange activity was strongly inhibited by Na+-gradient dissipators, monensin, and sodium ionophore as well as by CCCP, a protonophore. A. halophytica showed high Na+/H+ exchange activity at neutral and alkaline pH up to pH 10. Cells grown at pH 7.6 under high salinity exhibited higher Na+/H+ exchange activity than those grown under low salinity during 15 days of growth suggesting a role of Na+/H+ exchanger for salt tolerance in A. halophytica. Cells grown at alkaline pH of 9.0 also exhibited a progressive increase of Na+/H+ exchange activity during 15 days of growth. 相似文献
6.
Determination of oxidative metabolism in the brain using in vivo 13C NMR spectroscopy (13C MRS) typically requires repeated blood sampling throughout the study to measure blood glucose concentration and fractional
enrichment (input function). However, drawing blood from small animals, such as young rats, placed deep inside the magnet
is technically difficult due to their small total blood volume. In the present study, a custom-built animal holder enabled
temporary removal of the animal from the magnet for blood collection, followed by accurate repositioning in the exact presampling
position without degradation of B0 shimming. 13C label incorporation into glutamate C4 and C3 positions during a 120 min [1,6-13C2] glucose infusion was determined in 28-day-old rats (n = 4) under α-chloralose sedation using localized, direct-detected
in vivo 13C MRS at 9.4T. The tricarboxylic acid cycle activity rate (V
TCA) determined using a one-compartment metabolic modeling was 0.67 ± 0.13 μmol/g/min, a value comparable to previous ex vivo
studies. This methodology opens the avenue for in vivo measurements of brain metabolic rates using 13C MRS in small animals. 相似文献
7.
Héctor Guzmán Doan Van-Thuoc Javier Martín Rajni Hatti-Kaul Jorge Quillaguamán 《Applied microbiology and biotechnology》2009,84(6):1069-1077
The paper reports a study involving the use of Halomonas boliviensis, a moderate halophile, for co-production of compatible solute ectoine and biopolyester poly(3-hydroxybutyrate) (PHB) in a
process comprising two fed-batch cultures. Initial investigations on the growth of the organism in a medium with varying NaCl
concentrations showed the highest level of intracellular accumulation of ectoine (0.74 g L−1) at 10–15% (w/v) NaCl, while at 15% (w/v) NaCl, the presence of hydroxyectoine (50 mg L−1) was also noted. On the other hand, the maximum cell dry weight and PHB concentration of 10 and 5.8 g L−1, respectively, were obtained at 5–7.5% (w/v) NaCl. A process comprising two fed-batch cultivations was developed—the first culture aimed at obtaining high cell mass
and the second for achieving high yields of ectoine and PHB. In the first fed-batch culture, H. boliviensis was grown in a medium with 4.5% (w/v) NaCl and sufficient levels of monosodium glutamate, NH4+, and PO43−. In the second fed-batch culture, the NaCl concentration was increased to 7.5% (w/v) to trigger ectoine synthesis, while nitrogen and phosphorus sources were fed only during the first 3 h and then stopped
to favor PHB accumulation. The process resulted in PHB yield of 68.5 wt.% of cell dry weight and volumetric productivity of
about 1 g L−1 h−1 and ectoine concentration, content, and volumetric productivity of 4.3 g L−1, 7.2 wt.%, and 2.8 g L−1 day−1, respectively. At salt concentration of 12.5% (w/v) during the second cultivation, the ectoine content was increased to 17 wt.% and productivity to 3.4 g L−1 day−1. 相似文献
8.
Zhiliang Jiang Yanyan Fan Aihui Liang Guiqing Wen Qingye Liu Tingsheng Li 《Plasmonics (Norwell, Mass.)》2010,5(4):375-381
The resonance scattering spectral probe for Pb2+ was obtained using aptamer-modified AuPd Nanoalloy. In the pH 7.0 Na2HPO4–NaH2PO4 buffer solution, the aptamer interacted with AuPd nanoalloy particles to form stable aptamer-AuPd nanoalloy probe for Pb2+ that is stable in high concentration of salt. The probe combined with Pb2+ ions to form a G-quadruplex and to release AuPd nanoalloy particles that aggregate to form big particles which led the resonance
scattering (RS) intensity enhancing. The reaction solution was filtered by 0.15 μm membrane to obtain the filtration containing
aptamer-AuPd nanoalloy probe that has strong catalytic effect on the electrodeless nickel particle plating reaction between
Ni(II) and PO23− that exhibited a strong RS peak at 508 nm. The RS intensity at 508 nm decreased when the Pb2+ concentration increased. The decreased intensity (ΔI
508nm) is linear to the concentration of 0.08–42 nM Pb2+, with regress equation of DI508nm = 16.3 c + 1.5 \Delta {I_{{5}0{\rm{8nm}}}} = {16}.{3}\,c + {1}.{5} , correlation coefficient of 0.9965, and detection limit of 0.04 nM Pb2+. The RS assay was applied to the analysis of Pb2+ in wastewater, with satisfactory results. 相似文献
9.
Kirti Dhingra Petra Fousková Goran Angelovski Martin E. Maier Nikos K. Logothetis Éva Tóth 《Journal of biological inorganic chemistry》2008,13(1):35-46
Two new bismacrocyclic Gd3+ chelates containing a specific Ca2+ binding site were synthesized as potential MRI contrast agents for the detection of Ca2+ concentration changes at the millimolar level in the extracellular space. In the ligands, the Ca2+-sensitive BAPTA-bisamide central part is separated from the DO3A macrocycles either by an ethylene (L1) or by a propylene (L2) unit [H4BAPTA is 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid; H3DO3A is 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid]. The sensitivity of the Gd3+ complexes towards Ca2+ and Mg2+ was studied by 1H relaxometric titrations. A maximum relaxivity increase of 15 and 10% was observed upon Ca2+ binding to Gd2L1 and Gd2L2, respectively, with a distinct selectivity of Gd2L1 towards Ca2+ compared with Mg2+. For Ca2+ binding, association constants of log K = 1.9 (Gd2L1) and log K = 2.7 (Gd2L2) were determined by relaxometry. Luminescence lifetime measurements and UV–vis spectrophotometry on the corresponding Eu3+ analogues proved that the complexes exist in the form of monohydrated and nonhydrated species; Ca2+ binding in the central part of the ligand induces the formation of the monohydrated state. The increasing hydration number
accounts for the relaxivity increase observed on Ca2+ addition. A 1H nuclear magnetic relaxation dispersion and 17O NMR study on Gd2L1 in the absence and in the presence of Ca2+ was performed to assess the microscopic parameters influencing relaxivity. On Ca2+ binding, the water exchange is slightly accelerated, which is likely related to the increased steric demand of the central
part leading to a destabilization of the Ln–water binding interaction.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
A peptide heterodimer comprises two different receptor-targeting peptide ligands. Molecular imaging probes based on dual-receptor
targeting peptide heterodimers exhibit improved tumor targeting efficacy for multi-receptor expressing tumors compared with
their parent single-receptor targeting peptide monomers. Previously we have developed bombesin (BBN)-RGD (Arg-Gly-Asp) peptide
heterodimers, in which BBN and RGD are covalently connected with an asymmetric glutamate linker (J Med Chem 52:425–432, 2009).
Although 18F-labeled heterodimers showed significantly better microPET imaging quality than 18F-labeled RGD and BBN monomers in a PC-3 xenograft model which co-expresses gastrin-releasing peptide receptor (GRPR) and
integrin αvβ3, tedious heterodimer synthesis due to the asymmetric nature of glutamate linker restricts their clinical applications.
In this study, we report the use of a symmetric linker AEADP [AEADP = 3,3′-(2-aminoethylazanediyl)dipropanoic acid] for the
synthesis of BBN-RGD peptide heterodimer. The 18F-labeled heterodimer (18F-FB-AEADP-BBN-RGD) showed comparable microPET imaging results with glutamate linked BBN-RGD heterodimers, indicating that
the replacement of glutamate linker with AEADP linker did not affect the biological activities of BBN-RGD heterodimer. The
heterodimer synthesis is rather easy and straightforward. Because tumors often co-express multiple receptors, the use of a
symmetric linker provides a general method of fast assembly of various peptide heterodimers for imaging multi-receptor expressing
tumors. 相似文献
11.
Described here is a set of three-dimensional (3D) NMR experiments that rely on CACA-TOCSY magnetization transfer via the weak
3 \textJ\textCa\textCa ^{ 3} {\text{J}}_{{{\text{C}}\alpha {\text{C}}\alpha }} coupling. These pulse sequences, which resemble recently described 13C detected CACA-TOCSY (Takeuchi et al. 2010) experiments, are recorded in 1H2O, and use 1H excitation and detection. These experiments require alternate 13C-12C labeling together with perdeuteration, which allows utilizing the small
3 \textJ\textCa\textCa ^{ 3} {\text{J}}_{{{\text{C}}\alpha {\text{C}}\alpha }} scalar coupling that is otherwise masked by the stronger 1JCC couplings in uniformly 13C labeled samples. These new experiments provide a unique assignment ladder-mark that yields bidirectional supra-sequential
information and can readily straddle proline residues. Unlike the conventional HNCA experiment, which contains only sequential
information to the
1 3 \textCa ^{ 1 3} {\text{C}}^{\alpha } of the preceding residue, the 3D hnCA-TOCSY-caNH experiment can yield sequential correlations to alpha carbons in positions
i−1, i + 1 and i−2. Furthermore, the 3D hNca-TOCSY-caNH and Hnca-TOCSY-caNH experiments, which share the same magnetization pathway but use
a different chemical shift encoding, directly couple the 15N-1H spin pair of residue i to adjacent amide protons and nitrogens at positions i−2, i−1, i + 1 and i + 2, respectively. These new experimental features make protein backbone assignments more robust by reducing the degeneracy problem
associated with the conventional 3D NMR experiments. 相似文献
12.
Vesterdorf K Blache D Maloney SK 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2011,181(2):277-288
Panting is a mechanism that increases respiratory evaporative heat loss (REHL) under heat load. Because REHL uses body water,
it is physiologically and ecologically relevant to know under what conditions free-ranging animals use panting. We investigated
whether the cranial arterio-venous temperature difference could provide information about REHL. We exposed sheep to environments
varying in ambient dry bulb temperatures (Env 1: ~15°C, Env 2: ~25°C, Env 3: ~40°C, Env 4: ~40°C + infrared radiation) and
measured REHL simultaneously with carotid arterial (T
car) and jugular venous (T
jug) blood temperatures, as well as brain (T
brain) and rectal (T
rec) temperatures. REHL increased significantly with ambient temperature, from 18.4 ± 4.5 W at Env 1 to 79.5 ± 12.6 W at Env
4 (P < 10−6). While there was no effect of environment on T
car (P = 0.7) or T
jug (P = 0.09), the difference between them (T
a-v = T
car − T
jug) increased from Env 1 to Env 2 (P = 0.04) and from Env 3 to Env 4 (P = 0.008). T
a-v reached a maximum of 0.7 ± 0.2°C at Env 4 and was positively correlated with REHL across environments (r
2 = 0.78, F = 34.7, P < 10−3). Calculated cranial blood flow changed only from Env 2 to Env 3 (P = 0.002). The increase in REHL maintained homeothermy when dry heat loss decreased. While REHL could increase without generating
an increase in T
a-v, any increase in T
a-v was always associated with an increase in REHL. We conclude that the cranial T
a-v provides useful information about REHL in panting animals. 相似文献
13.
The expression of Na+, K+-ATPase α3 subunit and synaptosomal membrane Na+, K+-ATPase activity were analyzed after administration of ouabain and endobain E, respectively commercial and endogenous Na+, K+-ATPase inhibitors. Wistar rats received intracerebroventricularly ouabain or endobain E dissolved in saline solution or Tris–HCl,
respectively or the vehicles (controls). Two days later, animals were decapitated, cerebral cortex and hippocampus removed
and crude and synaptosomal membrane fractions were isolated. Western blot analysis showed that Na+, K+-ATPase α3 subunit expression increased roughly 40% after administration of 10 or 100 nmoles ouabain in cerebral cortex but
remained unaltered in hippocampus. After administration of 10 μl endobain E (1 μl = 28 mg tissue) Na+, K+-ATPase α3 subunit enhanced 130% in cerebral cortex and 103% in hippocampus. The activity of Na+, K+-ATPase in cortical synaptosomal membranes diminished or increased after administration of ouabain or endobain E, respectively.
It is concluded that Na+, K+-ATPase inhibitors modify differentially the expression of Na+, K+-ATPase α3 subunit and enzyme activity, most likely involving compensatory mechanisms. 相似文献
14.
Sphagnum, the main genus which forms boreal peat, is strongly affected by N and S deposition and raised temperature, but the physiological
mechanisms behind the responses are largely unknown. We measured maximum photosynthetic rate (NPmax), maximum efficiency of photosystem II [variable fluorescence (F
v)/maximum fluorescence yield (F
m)] and concentrations of N, C, chlorophyll and carotenoids as responses to N and S addition and increased temperature in Sphagnum balticum (a widespread species in the northern peatlands) in a 12-year factorial experiment. NPmax did not differ between control (0.2 g N m−2 year−1) and high N (3.0 g N m−2 year−1), but was higher in the mid N treatment (1.5 g N m−2 year−1). N, C, carotenoids and chlorophyll concentration increased in shoot apices after N addition. F
v/F
m did not differ between N treatments. Increased temperature (+3.6°C) had a small negative effect on N concentration, but had
no significant effect on NPmax or F
v/F
m. Addition of 2 g S m−2 year−1 showed a weak negative effect on NPmax and F
v/F
m. Our results suggest a unimodal response of NPmax to N addition and tissue N concentration in S. balticum, with an optimum N concentration for photosynthetic rate of ~13 mg N g−1. In conclusion, high S deposition may reduce photosynthetic capacity in Sphagnum, but the negative effects may be relaxed under high N availability. We suggest that previously reported negative effects
on Sphagnum productivity under high N deposition are not related to negative effects on the photosynthetic apparatus, but differences
in optimum N concentration among Sphagnum species may affect their competitive ability under different N deposition regimes. 相似文献
15.
Izawa S Kono K Mimura K Kawaguchi Y Watanabe M Maruyama T Fujii H 《Cancer immunology, immunotherapy : CII》2011,60(12):1801-1810
Human NK cells can be divided into two subsets, CD56dimCD16(+)NK and CD56brightCD16(−)NK cells, based on their expression of CD56 and CD16. In the present study, we analyzed the relationship between CD56dim/CD56bright NK cells and H2O2 in tumor-infiltrating NK cells in patients with gastric (n = 50) and esophageal (n = 35) cancer. The ratio of CD56dim NK cells infiltrating tumors gradually decreased according to disease progression. H2O2 was abundantly produced within tumor microenvironments, and there was an inverse correlation between CD56dim NK cell infiltration and H2O2 production. CD56dim NK cells are more sensitive to apoptosis induced by physiological levels of H2O2 than CD56bright NK cells. Furthermore, the exposure of NK cells to H2O2 resulted in the impairment of ADCC activity. In conclusion, H2O2 produced within tumor microenvironments inversely correlated with the infiltration of CD56dim NK cells, possibly due to their preferentially induced cell death. These observations may explain one of the mechanisms behind
NK cell dysfunction frequently observed in tumor microenvironments. 相似文献
16.
Muikku M Heikkinen T Solatie D Vesterbacka P 《Radiation and environmental biophysics》2011,50(4):531-538
A study to determine activity concentrations of 210Pb and 210Po in the urine of certain Finnish population groups was conducted, to investigate the variation in natural background level
of urinary excretion. The study participants were divided into three groups mainly based on their diet. The first group comprised
recreational fishermen and the second group represented people consuming more reindeer meat than an average Finn, while people
using drinking water with very high activity concentrations of 210Po were selected for the third group. The fourth group was a control group. The mean urinary excretion of 210Po in groups 1 and 2 was 73 and 100 mBq d−1, respectively. These values were higher than the value of the control group (20 mBq d−1) and the mean values reported in the literature. The mean daily urinary excretion of 210Pb in groups 1 and 2, 70 and 52 mBq d−1, was also slightly higher than that in the control group (32 mBq d−1). In contrast, the excretion rates of both 210Po and 210Pb for the members of group 3 were one to two orders of magnitude higher than those reported in the literature. This was clearly
due to the elevated levels of natural radionuclides in their drinking water. The present study demonstrates the importance
of possessing good knowledge of the background levels, in order to allow the determination of the additional exposure due,
for example, to the malevolent use of radiation. 相似文献
17.
CD4+CD25+Foxp3+ regulatory T (Treg) cells are believed to play an important role in suppressing autoimmunity and maintaining peripheral tolerance. How their survival is regulated in the periphery is less clear. Here we show that Treg cells express receptors for gamma chain cytokines and are dependent on an exogenous supply of these cytokines to overcome cytokine withdrawal apoptosis in vitro. This result was validated in vivo by the accumulation of Treg cells in Bim-/- and Bcl-2 tg mice which have arrested cytokine deprivation apoptosis. We also found that CD25 and Foxp3 expression were down-regulated in the absence of these cytokines. CD25+ cells from Scurfy mice do not depend on cytokines for survival demonstrating that Foxp3 increases their dependence on cytokines by suppressing cytokine production in Treg cells. Our study reveals that the survival of Treg cells is strictly dependent on cytokines and cytokine producing cells because they do not produce cytokines. Our study thus, demonstrates that different gamma chain cytokines regulate Treg homeostasis in the periphery by differentially regulating survival and proliferation. These findings may shed light on ways to manipulate Treg cells that could be utilized for their therapeutic applications. 相似文献
18.
Sergey M. Korotkov 《Journal of bioenergetics and biomembranes》2009,41(3):277-287
It is known that permeability of the inner mitochondrial membrane is low to most univalent cations (K+, Na+, H+) but high to Tl+. Swelling, state 4, state 3, and 2,4-dinitrophenol (DNP)-stimulated respiration as well as the membrane potential (ΔΨmito) of rat liver mitochondria were studied in media containing 0–75 mM TlNO3 either with 250 mM sucrose or with 125 mM nitrate salts of other monovalent cations (KNO3, or NaNO3, or NH4NO3). Tl+ increased permeability of the inner mitochondrial membrane to K+, Na+, and H+, that was manifested as stimulation of the swelling of nonenergized and energized mitochondria as well as via an increase
of state 4 and dissipation of ΔΨmito. These effects of Tl+ increased in the order of sucrose <K+ <Na+ ≤ NH4+. They were stimulated by inorganic phosphate and decreased by ADP, Mg2+, and cyclosporine A. Contraction of energized mitochondria, swollen in the nitrate media, was markedly inhibited by quinine.
It suggests participation of the mitochondrial K+/H+ exchanger in extruding of Tl+-induced excess of univalent cations from the mitochondrial matrix. It is discussed that Tl+ (like Cd2+ and other heavy metals) increases the ion permeability of the inner membrane of mitochondria regardless of their energization
and stimulates the mitochondrial permeability transition pore in low conductance state. The observed decrease of state 3 and
DNP-stimulated respiration in the nitrate media resulted from the mitochondrial swelling rather than from an inhibition of
respiratory enzymes as is the case with the bivalent heavy metals. 相似文献
19.
Glenn L. Butterfoss Eugene F. DeRose Scott A. Gabel Lalith Perera Joseph M. Krahn Geoffrey A. Mueller Xunhai Zheng Robert E. London 《Journal of biomolecular NMR》2010,48(1):31-47
Methionine residues fulfill a broad range of roles in protein function related to conformational plasticity, ligand binding,
and sensing/mediating the effects of oxidative stress. A high degree of internal mobility, intrinsic detection sensitivity
of the methyl group, and low copy number have made methionine labeling a popular approach for NMR investigation of selectively
labeled protein macromolecules. However, selective labeling approaches are subject to more limited information content. In
order to optimize the information available from such studies, we have performed DFT calculations on model systems to evaluate
the conformational dependence of 3
J
CSCC, 3
J
CSCH, and the isotropic shielding, σiso. Results have been compared with experimental data reported in the literature, as well as data obtained on [methyl-13C]methionine and on model compounds. These studies indicate that relative to oxygen, the presence of the sulfur atom in the
coupling pathway results in a significantly smaller coupling constant, 3
J
CSCC/3
J
COCC ~ 0.7. It is further demonstrated that the 3
J
CSCH coupling constant depends primarily on the subtended CSCH dihedral angle, and secondarily on the CSCC dihedral angle. Comparison
of theoretical shielding calculations with the experimental shift range of the methyl group for methionine residues in proteins
supports the conclusion that the intra-residue conformationally-dependent shift perturbation is the dominant determinant of
δ13Cε. Analysis of calmodulin data based on these calculations indicates that several residues adopt non-standard rotamers characterized
by very large ~100° χ3 values. The utility of the δ13Cε as a basis for estimating the gauche/trans ratio for χ3 is evaluated, and physical and technical factors that limit the accuracy of both the NMR and crystallographic analyses are
discussed. 相似文献
20.
Changes in oxygen consumption rate and Na+/K+-ATPase activity during early development were studied in the sea urchin Paracentrotus lividus Lam. The oxygen consumption rate increased from 0.12 μmol O2 mg protein−1 h−1 in unfertilized eggs to 0.38 μmol O2 mg protein−1 h−1 25 min after fertilization. Specific activity of the Na+/K+-ATPase was significantly stimulated after fertilization, ranging up to 1.07 μmol Pi h−1 mg protein−1 in the late blastula stage and slightly lower values in the early and late pluteus stages. 相似文献