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1.
Nuclear magnetic resonance T
1 and T
2 relaxivities ( r
1 and r
2) exhibit efficiency of a material to alter the relaxation rates (1/ T
1 and 1/ T
2), and they are being used for diagnostic purposes. The determination of total relaxivities ( r
1t and r
2t) of cystic fluid content and ameloblastoma may therefore be useful for discriminative purposes. In order to determine what
makes total relaxivities of hemorrhagic cysts, four sets of tubes containing pooled cyst were doped with increasing concentrations
of iron, copper, albumin, and γ-globulins. These sets were replaced in a phantom together with six individual cysts and one
ameloblastoma. The relaxation times were measured by magnetic resonance imaging operating at 1.5 T. The relaxivities of individual
ions and proteins were determined from the slope of the relation between relaxation rates and concentration, while total relaxivities
were determined by using the increases in relaxation rates and material content of cystic fluid (MC). Iron, copper, albumin,
and γ-globulins were found to be the sources of r
1t and r
2t. Each of r
1t, r
2t, r
1tMC, r
2tMC, and r
2t/ r
1t are distinctive parameters for each cystic category and ameloblastoma. Except for MC, the parameters measured for ameloblastoma
are significantly smaller than those of cysts. The similarity of the present results to those used in clinical applications
suggests that each of r
1t, r
2t, r
1tMC, r
2tMC, and r
2t/ r
1t has an ability to discriminate various fluids and masses. The present work also suggests that r
1tMC, r
2tMC, and r
2t/ r
1t can be determined in vivo. 相似文献
4.
Objective: To test whether resting oxygen uptake ( Vo 2), submaximal Vo 2, and maximal Vo 2 ( Vo 2max) differs between obese adolescents ( n = 18; BMI > 30) and a matched normal‐weight control group after adjustment for differences in fat‐free mass (FFM) and fat mass (FM). Research Methods and Procedures: FFM and FM were assessed by DXA. Resting Vo 2, submaximal Vo 2, and Vo 2max were measured by indirect calorimetry. Results: There was no difference in resting Vo 2 between groups after adjusting for FFM and FM. Submaximal Vo 2 did not differ between groups after adjusting for body weight. Percentage Vo 2max and NET Vo 2 ( Vo 2max ? resting Vo 2) were significantly higher in the obese group during submaximal exercise, however not after adjusting for body weight. Vo 2max was not significantly different between groups after adjusting for FFM. Discussion: When body compositions are appropriately controlled for, resting Vo 2, submaximal Vo 2, and Vo 2max do not differ between obese and normal‐weight adolescents. These data suggested that the higher relative Vo 2 observed in obese adolescent subjects is due to their higher FM and not to an impaired Vo 2max even though they may be less physically active. 相似文献
5.
Oxidative stress (OS) plays a major role in the gastrointestinal disorders. Although probiotics were reported to repress OS, few researches compared the antioxidant ability of different Bacillus strains and deciphered the mechanisms. To select a Bacillus strain with higher antioxidant capacity, we used H2O2 to induce intestinal porcine epithelial cell 1 (IPEC-1) OS model. The most suitable H2O2 concentration and incubation time were determined by the half lethal dose and methyl thiazolyl tetrazolium. Correlation analysis was performed to choose a sensitive indicator for OS. As for the comparison of Bacillus, cells were divided into control, Bacillus treatment, H2O2 treatment, and Bacillus pre-protection + H2O2 treatment. Bacillus were co-cultured with IPEC-1 for 3 h in Bacillus and Bacillus pre-protection + H2O2 treatments. Then, based on OS model, 300 μmol/L H2O2 was added into medium of H2O2 and Bacillus pre-protection + H2O2 treatments for another 12 h. Antioxidant and apoptosis gene expressions were detected to screen the target strain. Nuclear factor erythroid-derived 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein1 (Keap1) pathway, reactive oxygen species (ROS) production, mitochondrial membrane potential (Δψm), apoptosis, and necrosis were analyzed. Results revealed that heme oxygenase-1 (HO-1) gene expression had a positive correlation with H2O2 induction. Moreover, Bacillus amyloliquefaciens SC06 (SC06)-meditated IPEC-1 showed the best antioxidant capacity though modulating Nrf2 phosphorylation. Δψm was elevated, while ROS generation was reduced with SC06 pre-protection, resulting in decreased apoptosis and necrosis. Altogether, HO-1 expression could be regarded as an OS indicator. The regulation of Nrf2/Keap1 pathway and ROS production by SC06 are involved in alleviating OS of IPEC-1. 相似文献
6.
Gametophytic selection can drastically reduce the number of selection cycles during crop improvement programs. The objective
of the present investigation was to test whether the nature of inheritance of two unlinked disease-resistant loci, h
1 and h
2, against Fusarium wilt in chickpea ( Cicer arietinum L.) under gametophytic (pollen) selection was similar to that already observed at sporophytic level. A homozygous dominant
( H
1
H
1
H
2
H
2) susceptible genotype JG-62 was crossed to a recessive ( h
1
h
1
h
2
h
2) resistant genotype WR-315 to produce 20 F 1 hybrid seeds. In the following generation, flower buds of 10 F 1 hybrid plants were subjected to toxin stress before anthesis and the remaining ten control F 1 plants’ flowers were sprayed with water. Thirty-four selected BC 1 plants were generated by test crossing resistant WR-315 individuals with pollen from toxin-stressed F 1 individuals. Both control and treated F 1 plants were selfed to produce respective F 2 generations. Two DNA markers, CS-27 700bp and A07C 430bp, linked to susceptible alleles H
1 and H
2, respectively, were used to study the inheritance patterns of h
1 and h
2 loci in the F 2 and BC 1 generations. One hundred and forty-four selected F 2, 129 control F 2, and 34 selected backcross individuals were tested for the presence or absence of DNA markers. Except for the control F 2, observed ratios of selected F 2 and BC 1 populations exhibited significant chi-square deviations from expected monogenic and digenic ratios. Our results suggest that
gametophytic selection is as effective as that realized at the sporophytic level, and that the gametophytic selection can
be an effective breeding tool for plant breeding programs. 相似文献
7.
C 4 grasses of the NAD‐ME type ( Astrebla lappacea, Eleusine coracana, Eragrostis superba, Leptochloa dubia, Panicum coloratum, Panicum decompositum) and the NADP‐ME type ( Bothriochloa bladhii, Cenchrus ciliaris, Dichanthium sericeum, Panicum antidotale, Paspalum notatum, Pennisetum alopecuroides, Sorghum bicolor) were used to investigate the role of O 2 as an electron acceptor during C 4 photosynthesis. Mass spectrometric measurements of gross O 2 evolution and uptake were made concurrently with measurements of net CO 2 uptake and chlorophyll fluorescence at different irradiances and leaf temperatures of 30 and 40 °C. In all C 4 grasses gross O 2 uptake increased with increasing irradiance at very high CO 2 partial pressures ( pCO 2) and was on average 18% of gross O 2 evolution. Gross O 2 uptake at high irradiance and high pCO 2 was on average 3.8 times greater than gross O 2 uptake in the dark. Furthermore, gross O 2 uptake in the light increased with O 2 concentration at both high CO 2 and the compensation point, whereas gross O 2 uptake in the dark was insensitive to O 2 concentration. This suggests that a significant amount of O 2 uptake may be associated with the Mehler reaction, and that the Mehler reaction varies with irradiance and O 2 concentration. O 2 exchange characteristics at high pCO 2 were similar for NAD‐ME and NADP‐ME species. NAD‐ME species had significantly greater O 2 uptake and evolution at the compensation point particularly at low irradiance compared to NADP‐ME species, which could be related to different rates of photorespiratory O 2 uptake. There was a good correlation between electron transport rates estimated from chlorophyll fluorescence and gross O 2 evolution at high light and high pCO 2. 相似文献
9.
Herein, we described a scale-up strategy focused on the dissolved carbon dioxide concentration (dCO 2) during fed-batch cultivation of Chinese hamster ovary cells. A fed-batch culture process for a 2000-L scale stainless steel (SS) bioreactor was scaled-up from similarly shaped 200-L scale bioreactors based on power input per unit volume ( P/ V). However, during the 2000-L fed-batch culture, the dCO 2 was higher compared with the 200-L scale bioreactor. Therefore, we developed an alternative approach by evaluating the kLa values of O 2 ( kLa[O 2]) and CO 2 [ kLa(CO 2)] in the SS bioreactors as a scale-up factor for dCO 2 reduction. The kLa ratios [ kLa(CO 2)/ kLa(O 2)] were different between the 200-L and 2000-L bioreactors under the same P/ V condition. When the agitation conditions were changed, the kLa ratio of the 2000-L scale bioreactor became similar and the P/ V value become smaller compared with those of the 200-L SS bioreactor. The dCO 2 trends in fed-batch cultures performed in 2000-L scale bioreactors under the modified agitation conditions were similar to the control. This kLa ratio method was used for process development in single-use bioreactors (SUBs) with shapes different from those of the SS bioreactor. The kLa ratios for the SUBs were evaluated and conditions that provided kLa ratios similar to the 200-L scale SS bioreactors were determined. The cell culture performance and product quality at the end of the cultivation process were comparable for all tested SUBs. Therefore, we concluded that the kLa ratio is a powerful scale-up factor useful to control dCO 2 during fed-batch cultures. 相似文献
10.
Two experiments were conducted to determine the effects of 2-hydroxy-estradiol-17 β (2---OH---E 2; 0, 50 and 100 μM) and estradiol-17 β (E 2; 0, 25 and 50 μM) on prostaglandin (PG) E and PGF2α synthesis by day-10 pig blastocysts (day 0 is first day of estrus). Blastocysts were incubated in a modified Krebs-Ringer bicarbonate medium, supplemented with bovine serum albumin (4 mg/ml) and the vitamins and amino acids (essential and nonessential) in Minimum Essential Medium (without phenol red or antibiotics). The incubations were conducted at 39°C for three 2-h periods; the second and third periods included an E 2 or catechol estrogen treatment. Release of PGF2α into the culture medium decreased ( p<0.001) linearly with increasing concentrations of 2---H---E 2 in both periods. Release of PGE was not affected by 2---OH---E 2, therefore 2---OH---E 2 increased ( p<0.06) the PGE: PGF2α. When E 2 was added to the medium, release of PGE was decreased ( p<0.01) during the second and third periods. Release of PGF2α also was decreased ( p<0.05) by E 2 during period 2, but E 2 did not alter the PGE: PGF2α. Content of PGs in blastocysts at recovery was less than 10% of the PGs released in vitro. Therefore, these studies demonstrate effects of both the primary and catechol forms of E 2 on the synthesis of PGE and PGF2α. Catechol estrogens and E 2 may inhibit PG synthesis and modify the PGE: PGF2α during the establishment of pregnancy in pigs. 相似文献
11.
在百子莲胚性细胞中筛选到对超低温保存复合逆境具有积极响应的保护类蛋白脱水素(ApY_2SK_2),为探明ApY_2SK_2基因在复合逆境中的应答模式,该研究采用染色体步移技术克隆并分析了ApY_2SK_2编码基因上游1 200 bp的启动子序列。结果表明:(1)序列分析显示,该启动子含有多个与逆境和激素诱导相关的顺式调控元件;实时荧光定量PCR结果表明,ApY_2SK_2基因的表达具有组织特异性,在百子莲的叶和果中表达量较高,且在多种胁迫处理与ABA激素诱导下,其表达量显著升高。(2)成功构建了5个ApY_2SK_2启动子不同缺失片段驱动GUS基因的融合表达载体,经农杆菌转化、抗性筛选和PCR检测鉴定,获得T_3代纯和转基因拟南芥株系。(3) GUS组织化学染色结果显示,GUS基因在拟南芥幼苗全株、成年苗的叶、花和成熟果实中表达活性较强,但在未成熟果实中无明显表达;烟草瞬时表达结果显示,与对照组相比,在脱水胁迫和ABA处理下的ApY_2SK_2启动子不同缺失片段驱动GUS基因表达具有显著差异。(4)转基因拟南芥GUS活性测定结果显示,ApY_2SK_2启动子MBS元件和ABRE元件可响应干旱与渗透胁迫信号;ApY_2SK_2启动子LTR元件参与低温响应;ApY_2SK_2启动子-1 199~-262 bp区域包含多个串联的ABRE顺式调控元件(-373~-211 bp)对响应ABA信号具有主要调控作用。该研究结果揭示了ApY_2SK_2启动子的组织特异性,且启动子上的关键顺式调控元件对不同的胁迫和激素信号响应具有决定性调控作用。 相似文献
12.
为探索华南地区尾巨桉人工林和马占相思人工林地表温室气体的季节排放规律、排放通量和主控因子,采用静态箱-气相色谱法,对两种林型地表3种温室气体(CO_2、CH_4、N_2O)通量进行为期1年的逐月测定。结果表明:(1)尾巨桉人工林和马占相思人工林均为CO_2和N_2O的排放源,CH_4的吸收汇。马占相思林地表N_2O通量显著(P0.01)高于尾巨桉林,CO_2通量和CH_4通量无明显差异。(2)两种林型3种温室气体通量有着相似季节变化规律,地表CO_2通量均呈现雨季高旱季低的单峰规律;地表CH_4吸收通量表现为旱季高雨季低的单峰趋势;地表N_2O通量呈现雨季高旱季低且雨季内有两个峰值的排放规律。(3)地表CO_2、N_2O通量和土壤5 cm温度呈极显著(P0.01)正相关,3种温室气体地表通量同土壤含水量呈极显著(P0.01)或显著相关(P0.05)。(4)尾巨桉林和马占相思林温室气体年温室气体排放总量为31.014 t/hm~2和28.782 t/hm~2,均以CO_2排放占绝对优势(98.46%—99.15%),CH_4和N_2O处于次要地位。 相似文献
13.
Common responses to hypoxia include decreased body temperature ( Tb) and decreased energy metabolism. In this study, the effects of hypoxia and hypercapnia on Tb and metabolic oxygen consumption (V.O 2) were investigated in Japanese quail ( Coturnix japonica). When exposed to hypoxia (15, 13, 11 and 9% O 2), Tb decreased only at 11% and 9% O 2 compared to normoxia; quail were better able to maintain Tb during acute hypoxia after a one-week acclimation to 10% O 2. V.O 2 also decreased during hypoxia, but at 9% O 2 this was partially offset by increased anaerobic metabolism. Tb and V.O 2 responses to 9% O 2 were exaggerated at lower ambient temperature ( Ta), reflecting a decreased lower critical temperature during hypoxia. Conversely, hypoxia had little effect on Tb or V.O 2 at higher Ta (36 °C). We conclude that Japanese quail respond to hypoxia in much the same way as mammals, by reducing both Tb and V.O 2. No relationship was found between the magnitudes of decreases in Tb and V.O 2 during 9% O 2, however. Since metabolism is the source of heat generation, this suggests that Japanese quail increase thermolysis to reduce Tb. During hypercapnia (3, 6 and 9% CO 2), Tb was reduced only at 9% CO 2 while V.O 2 was unchanged. 相似文献
14.
The immediate effect of zinc (Zn) and hydrogen peroxide (H 2O 2) in Chara braunii was analyzed in short-time exposure experiments. The exposure concentrations were 12.3, 18.4, and 24.5 μmol L ?1 H 2O 2, 12, 60, and 120 mg L ?1 Zn, and 12.3 μmol L ?1 H 2O 2 + 12 mg L ?1 Zn, 12.3 μmol L ?1 H 2O 2 + 60 mg L ?1 Zn, and 18.4 μmol L ?1 H 2O 2 + 12 mg L ?1 Zn. The stress response of C. braunii was analyzed by measuring photosynthetic photosystem II activity, chlorophyll a and b and carotenoid contents, the H 2O 2 concentration, and antioxidant enzyme activities of ascorbic peroxidase, catalase, and guaiacol peroxidase. The short-term addition of Zn reduced pigment contents in C. braunii. Chlorophyll a and b and carotenoid contents in H 2O 2-exposed C. braunii were as high as in control plants. Photosynthesis was reduced in H 2O 2-treated C. braunii and the short-term addition of Zn did not affect the electron transport rate. H 2O 2 concentration and antioxidant enzyme activities in C. braunii were not significantly different between control and exposed plants. Trends of enzymatic adaptation were described: the H 2O 2-induced stress response was characterized by increased antioxidant enzyme activities, whereas Zn inactivated catalase in C. braunii. 相似文献
15.
Copper(II) ,-dicarboxylate complexes of general formulae, [Cu(O 2C(CH 2) nCO 2)]· xH 2O, [Cu(O 2C(CH 2) nCO 2) (phen) 2]· xH 2O and [Cu(O 2C(CH 2) nCO 2)(bipy) y]· xH 2O ( n=1–8; y=1, 2; phen = 1,10-phenanthroline; bipy = 2,2-bipyridine) were synthesised. These copper complexes, some related manganese(II) complexes and the metal-free ligands were screened in vitro for their ability to inhibit the growth of Candida albicans. Metal-free 1,10-phenanthroline and all of the copper(II) and manganese(II) phenanthroline complexes were potent growth inhibitors, with only one bipyridine complex, [Cu(O 2C(CH 2)CO 2)(bipy) 2]·2H 2O, having moderate activity. The remaining substances were effectively inactive. Complexes which were active against C. albicans also proved effective against C. glabrata, C. tropicalis and C. kreusi with the manganese complexes retaining superior activity. For the phenanthroline complexes the active drug species is thought to be the dication [M(phen) 2(H 2O) n] 2+ (M = Cu, Mn). Escherichia coli and Staphylococcus aureus were resistant to all of the metal complexes and also to metal-free 1,10-phenanthroline. Only the copper phenanthroline complexes showed intermediate activity against Pseudomonas aeruginosa. 相似文献
16.
Elevated atmospheric CO 2 is known to affect plant–insect herbivore interactions. Elevated CO 2 causes leaf nitrogen to decrease, the ostensible cause of herbivore compensatory feeding. CO 2 may also affect herbivore consumption by altering chemical defenses via changes in plant hormones. We considered the effects of elevated CO 2, in conjunction with soil fertility and damage (simulated herbivory), on glucosinolate concentrations of mustard ( Brassica nigra) and collard ( B. oleracea var. acephala) and the effects of leaf nitrogen and glucosinolate groups on specialist Pieris rapae consumption. Elevated CO 2 affected B. oleracea but not B. nigra glucosinolates; responses to soil fertility and damage were also species‐specific. Soil fertility and damage also affected B. oleracea glucosinolates differently under elevated CO 2. Glucosinolates did not affect P. rapae consumption at either CO 2 concentration in B. nigra, but had CO 2‐specific effects on consumption in B. oleracea. At ambient CO 2, leaf nitrogen had strong effects on glucosinolate concentrations and P. rapae consumption but only gluconasturtiin was a feeding stimulant. At elevated CO 2, direct effects of leaf nitrogen were weaker, but glucosinolates had stronger effects on consumption. Gluconasturtiin and aliphatic glucosinolates were feeding stimulants and indole glucosinolates were feeding deterrents. These results do not support the compensatory feeding hypothesis as the sole driver of changes in P. rapae consumption under elevated CO 2. Support for hormone‐mediated CO 2 response (HMCR) was mixed; it explained few treatment effects on constitutive or induced glucosinolates, but did explain patterns in SEMs. Further, the novel feeding deterrent effect of indole glucosinolates under elevated CO 2 in B. oleracae underscores the importance of defensive chemistry in CO 2 response. We speculate that P. rapae indole glucosinolate detoxification mechanisms may have been overwhelmed under elevated CO 2 forcing slowed consumption. Specialists may have to contend with hosts with poorer nutritional quality and more effective chemical defenses under elevated CO 2. 相似文献
17.
The cytological possibility of gene transfer from Sinapis pubescens to Brassica napus was investigated. Intergeneric hybrids between Brassica napus (2n = 38) and Sinapis pubescens (2n = 18) were produced through ovary culture. The F 1 hybrids were dihaploid and the chromosome configurations were (0–1)
III
+ (2–11)
II
+ (5–24)
I
. One F 2 plant with 38 chromosomes was obtained from open pollination of the F 1 hybrid. Thirty-one seeds were obtained from the backcross of the F 2 plant with B. napus. Five out of seven plants had 38 chromosomes, and the pollen stainability ranged from 0% to 81.4%. In the B 2 plants obtained from the backcross of B 1 plants with B. napus, 66.7% of the plants examined had 38 chromosomes. S. pubescens may become a gene source for the improvement of B. napus. 相似文献
18.
We show here that CO 2 partial pressure ( pCO 2) and temperature significantly interact on coral physiology. The effects of increased pCO 2 and temperature on photosynthesis, respiration and calcification rates were investigated in the scleractinian coral Stylophora pistillata. Cuttings were exposed to temperatures of 25°C or 28°C and to pCO 2 values of ca. 460 or 760 μatm for 5 weeks. The contents of chlorophyll c2 and protein remained constant throughout the experiment, while the chlorophyll a content was significantly affected by temperature, and was higher under the ‘high‐temperature–high‐ pCO 2’ condition. The cell‐specific density was higher at ‘high pCO 2’ than at ‘normal pCO 2’ (1.7 vs. 1.4). The net photosynthesis normalized per unit protein was affected by both temperature and pCO 2, whereas respiration was not affected by the treatments. Calcification decreased by 50% when temperature and pCO 2 were both elevated. Calcification under normal temperature did not change in response to an increased pCO 2. This is not in agreement with numerous published papers that describe a negative relationship between marine calcification and CO 2. The confounding effect of temperature has the potential to explain a large portion of the variability of the relationship between calcification and pCO 2 reported in the literature, and warrants a re‐evaluation of the projected decrease of marine calcification by the year 2100. 相似文献
19.
The photosynthetic responses of potato [ Solanum tuberosum (L.)] to CO 2 enrichment were studied in open-topped field chambers. Plants were raised in 2.4 m 2 plastic enclosures over three growing seasons from 1996 to 1998. Plots were continuously fertilized with 1, 1.5 and 2 times ambient daytime CO 2. These were the low (L), medium (M) and high (H) CO 2 treatments, respectively. Tuber dry matter yields were increased 9 and 40%, respectively, in the M and H treatments compared to the L CO 2 treatment. Net photosynthesis (P
n
) and conductance to water vapor ( g
s) of upper canopy leaves were measured at 1 or 2-week intervals at the growth CO 2 partial pressure and then P
n
of plants in the L treatment was determined at 70 Pa CO 2 (L 70). Leaflet P
n
rates averaged over all measurement dates were 28, 49 and 84% greater, respectively, in the M, H and L 70 CO 2 treatments, compared to plants in the L treatment. Changes of P
n
in response to the L, M and H CO 2 treatments were proportional to increases of internal CO 2 (C i) and at low leaf-to-air vapor pressure deficits mid-day g
s was inversely related to growth CO 2. The ratio of P
n
at H compared to L 70 was 0.81 when averaged over all measurement dates. Leaf soluble protein, Rubisco protein and chlorophyll ( a + b) levels were unaffected by CO 2 treatment. Total Rubisco activity was decreased by CO 2 enrichment in 1998, but percent activation was similar in the L, M and H plots. Leaf starch was increased but sucrose, glucose and fructose were unaffected by CO 2 treatment. The above findings indicated that a down regulation of P
n
in response to elevated CO 2 was consistently observed in field-grown potato. This was attributed to a decrease of total Rubisco activity that was potentially due to the presence of inhibitory compounds bound to the active site of the enzyme. The amount of photosynthetic acclimation observed here did not preclude a persistent enhancement of P
n
under the elevated CO 2 growth conditions. 相似文献
20.
Experiments were carried out to investigate the changes in CO 2 assimilation, photon allocation, and photosynthetic electron flux in leaves of cucumber ( Cucumis sativus L.) plants after chilling stress. Chilling significantly decreased CO 2 assimilation, the energy flux via linear electron transport ( J
PS2) and non-constitutive thermal dissipation ( J
NPQ) but increased fluorescence and constitutive thermal dissipation ( J
f,D) in chilling-sensitive genotype Jinyan No. 4. In contrast, chilling had little effects on J
NPQ and J
f,D although CO 2 assimilation and J
PS2 were inhibited in chilling-tolerant genotype Jinchun No. 3. In parallel with the reduction in J
PS2, electron flux to oxygenation and carboxylation by ribulose-1,5-bisphosphate carboxylase/oxygenase all significantly decreased
while electron flux to O 2 significantly increased, especially in chilling-sensitive genotype. Thermal and fluorescence dissipation were the main energy
dissipation pathways whilst water-water cycle was an important electron sink when photosynthetic carbon reduction was suppressed
after chilling. Chilling sensitivity of the photosynthetic apparatus was related to the operation of different photoprotection
mechanisms. 相似文献
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