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1.
Effects of carbohydrates on membrane stability at low water activities 总被引:19,自引:0,他引:19
L M Crowe R Mouradian J H Crowe S A Jackson C Womersley 《Biochimica et biophysica acta》1984,769(1):141-150
The relative effectiveness of a variety of carbohydrates in preserving the structural and functional integrity of membranes at low water activities was studied, using Ca-transporting microsomes from muscle as a model membrane. The order of effectiveness (greatest to lowest) was: trehalose, lactose, maltose, cellobiose, sucrose, glucose, fructose, sorbitol, raffinose, myo-inositol, glycerol. At the highest concentrations of the most effective sugars tested, microsomes were obtained upon rehydration that were similar structurally and functionally to fresh membranes. The least effective carbohydrates, alcohol sugars, all appear to be fusogenic. A structural explanation for relative effectiveness of the sugars was sought, but no clear relationship was found, except that effectiveness does not appear to be related to the number of position of hydroxyl groups available for hydrogen bonding. 相似文献
2.
Characterization of an extracellular keratinase of Trichophyton simii and its role in keratin degradation 总被引:1,自引:1,他引:0
The ability of Trichophyton simii HN 50, isolated from the Ghana Bird Sanctuary, Bharatpur, India, to produce extracellular keratinase was studied. Enzyme was produced on a keratin salt broth medium at pH7 and a temperature of 28 ± 1 °C. Enzyme secretion was best at 15 days of incubation. Asparagine and keratin were repressive to enzyme yield in comparison to gelatin. No relationship was observed between enzyme release and biomass. Exogenous sugars suppressed keratinase production in descending order as follows: glucose > mannose > maltose > arabinose > fructose. The enzyme showed ability to degrade all of the 3 keratin substrates. Buffalow skin was best degraded in the absence of glucose while chicken feathers were the least degraded in its presence.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
3.
Differences in the taste quality of maltose and sucrose in rats: issues involving the generalization of conditioned taste aversions 总被引:3,自引:3,他引:0
The present study employed a conditioned taste aversion generalizationparadigm to test the hypothesis that maltose produces tastesensations in the rat which are qualitatively distinguishablefrom sucrose. Since stimulus generalization can occur in boththe quality and intensity domains, an intrachemical (acrossconcentration) generalization gradient was established to aidin the interpretation of the interchemical (across molecules)generalization gradient. Moreover, since the commonly used intaketest is vulnerable to nontaste post-ingestional influences,the present study measured immediate responses to 100 µlstimulus samples, thus increasing our confidence that the behaviorwas under orosensory control. In Experiment 1, naive water deprivedrats were trained in a specially designed gustometer to maintaindrinking-spout contact for intermittent water reinforcement.Following this, rats in the experimental group were given threeexposures to 0.1 M sucrose on separate days, with the firsttwo exposures immediately preceding an injection of LiCl. Acontrol group was treated identically but received distilledwater instead of sucrose. Rats were then tested in the gustometerfor their avoidance of three equimolar concentrations of sucroseand maltose. Rats received ten trials of each stimulus quasi-randomlypresented in two sessions. Results indicated that all sucroseconcentrations were avoided (in experimental group only), butonly the 0.3 M concentration of maltose was avoided. The lowestsucrose concentration was significantly less avoided than thehigher concentrations. Intensity generalization gradients aresuch that intensities weaker than the conditioned stimulus (CS)produce just as much or less of a conditioned response (CR)and intensities stronger than the CS produce just as much ora greater CR than that elicited by the CS itself. Therefore,based on the results of Experimental, it was predicted thatif 0.1 M maltose served as the CS, the order of avoidance shouldbe: 0.3 M sucrose 0.1 M sucrose 0.03 M sucrose 0.3 M maltose 0.1 M maltose 0.03 M maltose, if it were true that maltoseand sucrose produce identical sensations that differ only inintensity. Experiment 2 explicitly tested this prediction usingthe same procedure as Experiment 1 except that 0.1 M maltoseserved as the CS. The observed order of avoidance was 0.3 Mmaltose > 0.1 M maltose > 0.03 M maltose = 0.3 M sucrose= 0.1 M sucrose = 0.03 M sucrose. In both experiments the intrachemicalgeneralization gradient broadened and the interchemical generalizationgradient steepened upon retesting. In conclusion, qualitativedifferences between maltose and sucrose explain the outcomesof these experiments better than differences in the relativeintensity of these sugars at isomolar concentrations. 相似文献
4.
Unimbibed Amaranthus caudatus seeds were found to contain stachyose, raffinose, verbascose, sucrose, galactinol, myo-inositol, glucose and fructose, while no galactose, maltose and maltotriose was detected. During imbibition, seed concentrations
of verbascose, stachyose, raffinose, galactinol, myo-inositol (temporary) and fructose (transient) were observed to decrease; concentrations of galactose and maltose remained
fairly constant, while those of sucrose, glucose and maltotriose increased, the increase in sucrose concentration was only
temporary. Effects of gibberellin A3 (GA3) at 3 × 10−4 M and ethephon at 3 × 10−4 M alone or in the presence of methyl jasmonate (Me-JA) at 10−3 M on concentrations of soluble sugars during germination of A. caudatus seeds were examined. Me-JA was found to inhibit seed germination and fresh weight of the seeds, but did not affect sucrose,
myo-inositol, galactose and maltose concentrations during imbibition for up to 20 h. The exogenously applied GA3 was observed to enhance germination, stachyose breakdown and glucose concentration after 20 h of incubation. Ethephon stimulated
seed germination as well as utilisation of stachyose, galactinol (both after 14 and 20 h) and raffinose (after 14 h of incubation).
Although the stimulatory effect of either GA3 or ethephon on seed germination was blocked by Me-JA; these stimulators increased mobilisation of raffinose and stachyose,
but only ethephon enhanced both glucose and fructose after 14 and/or 20 h of incubation in the presence of Me-JA. The maltose
concentration was increased by both GA3 and ethephon alone and in the presence of Me-JA. Of the growth regulators studied, ethephon alone and/or in combination with
Me-JA significantly increased the concentrations of glucose, fructose, galactose, maltose and maltotriose. The differences
in sugar metabolism appear to be linked to ethylene or GA3 applied simultaneously with Me-JA. 相似文献
5.
Ailong Wang Yu Wang Tianyi Jiang Lixiang Li Cuiqing Ma Ping Xu 《Applied microbiology and biotechnology》2010,87(3):965-970
Corncob molasses, a waste by-product in xylitol production, contains high concentrations of mixed sugars. In the present study,
corncob molasses was used to produce 2,3-butanediol (BD) using Klebsiella pneumoniae SDM. This was the first report on the use of corncob molasses to produce bulk chemicals. Our results indicated that K. pneumoniae SDM can utilize various sugars contained in the corncob molasses in a preferential manner: glucose > arabinose > xylose.
It was shown that high sugars concentration had an inhibitory effect on the cells growth and BD production. The maximum concentration
of BD was 78.9 g/l after 61 h of fed-batch fermentation, giving a BD productivity of 1.3 g/l h and a yield of 81.4%. The present
study suggests that the low-cost corncob molasses could be used as an alternative substrate for the production of BD by K. pneumoniae SDM, as well as a potential carbon source for production of other high-value chemicals. 相似文献
6.
We compared the metabolism of eight di- and trichlorobiphenyls by eight bacterial strains chosen to represent a broad range
of degradative activity against polychlorinated biphenyls (PCBs). The PCB congeners used were 2,3-, 2,3′-, 2,4′-, 3,3′-, 2,3,3′-,
2,4,4′-, 2,5,3′-, and 3,4,2′-chlorobiphenyl. The bacterial strains used wereCorynebacterium sp. MB1,Alcaligenes strainsA. eutrophus H850 andA. faecalis Pi434, andPseudomonas strains LB400 and H1130,P. testosteroni H430 and H336, andP. cepacia H201. The results indicated that both the relative rates of primary degradation of PCBs and the choice of the ring attacked
were dependent on the bacterial strain used. The bacterial strains exhibited considerable differences in their relative reactivity
preferences for attack on mono- and dichlorophenyl groups and in the degree to which the attack was affected by the chlorine
substitution pattern on the nonreacting ring. For MB1 the reactivity pattern was 3-≥4-≫2-chlorophenyl with no attack on 2,4-
or 2,5-chlorophenyl groups. This strain was relatively insensitive to the chlorine substitution pattern on the nonreacting
ring. Strains H1130, H430, H201, and Pi434 exhibited the same reactivity preferences as MB1, but for these strains (and for
all others tested) the chlorination pattern on the nonreacting ring had a strong effect. For strain H336 the reactivity preference
was 4-≥2->2,4-≥3-chlorophenyl, with no evidence of attack on 2,5-chlorophenyl rings. For strains H850 and LB400 the relative
reactivity was 2->2,5->3-≫2,4->4-chlorophenyl. On this basis we propose that the eight bacterial strains represent four distinct
classes of biphenyl/PCB-dioxygenase activity.
The types of products formed were largely strain-independent and were determined primarily by the chlorine substitution pattern
on the reacting ring. When the reacting ring was an unsubstituted phenyl or a 2-chlorophenyl group, the products were chlorobenzoic
acids in high yields; for a 3-chlorophenyl ring, both chlorobenzoic acids and chloroacetophenones in moderate yields; and
for a 4- or 2,4-chlorophenyl group, chlorobenzoic acids in low yields with an apparent accumulation ofmeta ring-fission product. Strains H850 and LB400 were able to degrade the 3-chlorobenzoic acid that they produced from the degradation
of 2,3′-chlorobiphenyl. We conclude that despite differences among strains in the specificity of the initial dioxygenase,
the specificities of the enzymes responsible for the subsequent degradation to chlorobenzoic acid and/or chloroacetophenone
are quite similar for all strains. 相似文献
7.
A. Bevilacqua M. R. Corbo M. Mastromatteo M. Sinigaglia 《World journal of microbiology & biotechnology》2008,24(9):1721-1729
A four variables-five levels Central Composite Design (CCD) was developed to model the individual and interactive effects
of carbohydrates (lactose or maltose), yeast extract, di-ammonium hydrogen citrate and pH on the biomass production (Abs600 nm), viable and cultivable cell number and acidifying ability of a probiotic strain of Lactobacillus plantarum, isolated from table olives “Bella di Cerignola”. pH values were modeled through a negative Gompertz equation, in order to
obtain the parameter α (metabolic adaptation time). This value and the biomass were submitted to a stepwise procedure and
second order polynomial equations were derived. The parameter α was affected by the initial pH and lactose; the effect of
the maltose, however, was not significant. The biomass production increased with increasing of yeast extract, di-ammonium
hydrogen citrate and maltose concentrations and was maximum at pH 6.0 and 20 g l−1 of lactose. 相似文献
8.
α-Amylase (EC 3.2.1.1) expression was found in calli of French bean (Phaseolus vulgaris L. cv Goldstar). We examined enzyme activity in the calli to investigate influence of gibberellin and sugars on enzyme expression.
After subculture of the calli, α-amylase activity decreased, and then increased at a stationary phase of callus growth. Exogenous
application of gibberellin and an inhibitor of gibberellin synthesis, uniconazole, did not have any significant effects on
the enzyme expression. Sugar starvation increased the activity, while addition of metabolizable sugars, such as sucrose, glucose
and maltose, to the medium repressed expression. Addition of 6% mannitol, a non-metabolizable sugar, to the medium induced
higher α-amylase expression as compared to addition of 3% mannitol. This result suggests that osmotic stress enhances α-amylase
activity in the calli. Furthermore, high concentrations of agar in the medium increased α-amylase activity in the calli. It
is probable that high concentrations of agar prevented incorporation of nutrient into the calli and induced the α-amylase
activity in the calli. 相似文献
9.
The putative role(s) of a mechanically gated (MG) cation channel in Xenopus oocyte growth, maturation, fertilization and embryogenesis has been examined. Using a pharmacological approach, we have tested
the effects of the MG channel blockers, gadolinium, gentamicin and amiloride on the above developmental events. Our results
indicate that oocyte maturation, fertilization and early embryogenesis (up to the free-swimming stage 45) can proceed normally
in the presence of concentrations of agents that either completely abolish (i.e., ≥10 μm Gd3+) or partially block (i.e., 1 mm gentamicin) single MG channel activity as measured by patch-clamp recording. However, we also find that higher concentrations
of Gd3+ (≥50 μm) can lead to an increased percentage (>20%) of axis-perturbed embryos compared with control (<1%) and that amiloride (0.5
mm) reduces the success of fertilization (from 100% to <50%) and increases mortality (by ∼75%) in developing embryos. Furthermore,
we find that all three agents inhibit oocyte growth in vitro. However, their order of effectiveness (amiloride > gentamicin
> Gd3+) is opposite to their order for blocking MG channels (Gd3+≫ gentamicin > amiloride). These discrepancies indicated that the drugs effects occur by mechanisms other than, or in addition
to, MG channel block. Our results provide no compelling evidence for the idea that MG channel activity is critical for development
in Xenopus. This could mean that there are other mechanisms in the oocyte that can compensate when MG channel activity is blocked or
that the protein that forms the channel can undergo additional interactions that result in a function insensitive to MG channel
blockers.
Received: 27 March 1998/Revised: 10 June 1998 相似文献
10.
Ethidium monoazide bromide (EMA) treatment of pure culture and environmental waters at low concentrations (1.0–7.5 μg/ml)
indicated effective enumeration of viable and viable but nonculturable Escherichia coli in pure cultures, creek waters, and secondary activated sludge effluent samples by quantitative polymerase chain reaction
(qPCR) amplification of the uidA and fliC gene targets at turbidity values <10 NTU. However, EMA treatment was not effective in primary clarifier and secondary trickling
filter effluents where turbidities were ≥10 NTU. In viable pure cultures, rapidly dividing and senescent cells were most affected
by increasing EMA concentrations. Amplification of heat-killed pure bacterial cultures decreased 4 to 6 logs depending on
EMA concentration and culture age. The greatest difference was observed in 5-h cultures using 7.5 μg/ml EMA. Turbidity (≥100
NTU) in environmental samples inhibited EMA effectiveness on viability discrimination. Enumeration of E. coli in certain wastewaters using EMA-qPCR was similar to culture suggesting that EMA treatment could be incorporated into qPCR
assays for the quantification of viable bacteria increasing assay time no more than 30 min. Our results indicate that EMA
can be used in routine qPCR assays, but optimum conditions for exposure must be identified for each sample type due to sample
matrix effects such as turbidity. 相似文献
11.
Kyoung-Cheol Kim Si-Wouk Kim Myong-Jun Kim Seong-Jun Kim 《Biotechnology and Bioprocess Engineering》2005,10(1):52-59
The study was targeted to saccharify foodwastes with the cellulolytic and amylolytic enzymes obtained from culture supernatant
ofTrichoderma harzianum FJ1 and analyze the kinetics of the saccharification in order to enlarge the utilization in industrial application.T. harzianum FJ1 highly produced various cellulolytic (filter paperase 0.9, carboxymethyl cellulase 22.0, β-glucosidase 1.2, Avicelase
0.4, xylanase 30.8, as U/mL-supernatant) and amylolytic (α-amylase 5.6, β-amylase 3.1, glucoamylase 2.6, as U/mL-supernatant)
enzymes. The 23–98 g/L of reducing sugars were obtained under various experimental conditions by changing FPase to between
0.2–0.6 U/mL and foodwastes between 5–20% (w/v), with fixed conditions at 50°C, pH 5.0, and 100 rpm for 24 h. As the enzymatic
hydrolysis of foodwastes were performed in a heterogeneous solid-liquid reaction system, it was significantly influenced by
enzyme and substrate concentrations used, where the pH and temperature were fixed at their experimental optima of 5.0 and
50°C, respectively. An empirical model was employed to simplify the kinetics of the saccharification reaction. The reducing
sugars concentration (X, g/L) in the saccharification reaction was expressed by a power curve (X=K·t
n) for the reaction time (t), where the coefficient,K andn, were related to functions of the enzymes concentrations (E) and foodwastes concentrations (S), as follow:K=10.894 Ln(E·S
2)-56.768,n=0.0608·(E/S)−0.2130. The kinetic developed to analyze the effective saccharification of foodwastes composed of complex organic compounds could
adequately explain the cases under various saccharification conditions. The kinetics results would be available for reducing
sugars production processes, with the reducing sugars obtained at a lower cost can be used as carbon and energy sources in
various fermentation industries. 相似文献
12.
Studies have been undertaken to investigate the effect of sugars on the thermal and rheological properties of sago starch. Sugars were found to increase the gelatinization temperature Tgel, and gelatinization enthalpy ΔH. Tgel and ΔH increased in the following order: control (water alone) < ribose < fructose < glucose < maltose < sucrose. The increase in ΔH was greater for 50% starch compared to 10% starch samples. The swelling factors in the presence of sugar were higher compared to the control for sugar concentrations below 25% but were lower at sugar concentration greater than 25%. These effects are discussed in terms of the antiplaticizing effect of the sugars compared to water, the influence of sugar–starch interactions and also the effect of the sugars on water structure. The storage modulus G′, the rate constant of gelation k, and the gel strength were significantly reduced in the presence of sugars. Generally G′ and k decreased in the following order: control (water alone) > hexose > disaccharide > pentoses. This has been attributed to the reduced proportion of amylose leached following gelatinizatison. In the presence of hexoses the freeze–thaw stability of starch gels decreased while in the presence of disaccharides and pentoses the freeze–thaw stability was slightly improved. © 1999 John Wiley & Sons, Inc. Biopoly 50: 401–412, 1999 相似文献
13.
Calcium, magnesium and potassium dynamics in decomposing litter of three tree species were measured over a two-year period. The speices studied were flowering dogwood (Cornus florida), red maple (Acer rubrum) and chestnut oak (Quercus prinus). The order of decomposition was:C. florida>A. rubrum>Q. prinus.Calcium concentrations increased following any initial leaching losses. However, there were net releases of Ca from all three litter types since mass loss exceeded the increases in concentration. Net release of Ca by the end of two years from all three species combined was 42% of initial inputs in litterfall. Magnesium concentrations increased in the second year, following decreases due to leaching during the first year inC. florida andA. rubrum litter. Net release of Mg by the end of two years was 58% of initial inputs. Potassium concentrations decreased rapidly and continued to decline throughout the study. Net release of K by the end of two years was 91% of initial inputs.These data on cation dynamics, and similar data on N, S and P dynamics from a previous study, were combined with annual litterfall data to estimate the release of selected nutrients from foliar litter of these tree species at the end of one and two years of decomposition. The relative mobility of all six elements examined in relation to mass loss after two years was; K>Mg>mass>Ca>S>P>N. 相似文献
14.
Summary The present study aimed to evaluate the response to salinity of Populus euphratica, which is more salt-resistant than other poplar cultivars, at the cellular level. To this purpose, callus was induced from
shoot segments of P. euphratica on Murashige and Skoog (MS) medium supplemented with 0.5 mg l−1 (2.2 μM) 6-benzyladenine (BA) and 0.5 mg l−1 (2.7 μM 1-naphthaleneacetic acid (NAA). Callus was transferred to MS medium supplemented with 0.25 mg l−1 (1.1 μM) BA and 0.5 mg l−1 NAA. The relative growth rate of callus reached a maximum in the presence of 50 mmol l−1 NaCl and growth was inhibited with increasing NaCl concentrations. Examination of the changes of osmotic substances under
salt stress showed that accumulation of proline, glycine betaine, and total soluble sugars increased with increasing salt
concentrations. The results indicate that the response of the callus of P. euphratica to salt stress is similar to that of the whole plant. 相似文献
15.
Gabriela Lorenc-Plucińska Anna Szadel Andrzej Pluciński Renata Matysiak 《Acta Physiologiae Plantarum》2002,24(2):123-129
Sulphite at concentrations from 0.5 to 5.0 mM was supplied to illuminated, detached poplar (Populus deltoides Bartr. ex Marsh) leaves via the transpiration stream. Chlorophyll a fluorescence parameters, the contents of fructose-2,6-bisphosphate (Fru2,6BP) and starch, and extractable specific activity
of sucrose-phosphate synthase (SPS), sucrose synthase (SuSy), acid invertase (AI), neutral invertase (NI), ATP-dependent fructose-6-phosphate
1-phosphotransferase (PFK) and pyrophosphate-dependent fructose-6-phosphate 1-phosphotransferase (PFP) were measured. Chlorophyll
fluorescence parameters appeared to be unaffected by sulphite. Application of ≥ 1.0 mM sulphite led to an increase in the
content of Fru2,6BP and starch. There was also a decline in the activity of SPS, NI and PFK. On the other hand, the influence
of sulphite on the activity of AI and PFP was negligible. Specific activity of SuSy was inhibited by 1.0 and 2.5 mM but activated
by 5.0 mM of sulphite. On the basis of the results obtained in the present study, we postulate that sulphite at concentrations
≥ 1.0 mM inhibits primarily sucrose synthesis, favours starch accumulation and has an indirect effect on the sucrolytic activities
in poplar leaves. 相似文献
16.
Ronald Jildmalm Mats Amundin Matthias Laska 《International journal of primatology》2008,29(6):1535-1547
We aimed to assess spontaneous food preferences in captive white-handed gibbons and to analyze whether they correlate with
nutrient composition. Via a 2-alternative choice test, we repeatedly presented 3 male Hylobates lar with all possible binary combinations of 10 types of food that are part of their diet in captivity and found the following
rank order of preference: grape > banana = fig > apple > pear > honeydew melon > carrot > tomato > cucumber > avocado. Correlational
analyses revealed a highly significant positive correlation between the food preference ranking and the total carbohydrate,
fructose, and glucose contents of the foods (p < 0.01, respectively). With the exception of the trace mineral selenium (p < 0.05), there was no other significant correlation with any other macro- or micronutrient. In addition, the food preferences
were stable across the day because rankings obtained from tests performed at 0900, 1200, and 1500 h, respectively, did not
differ significantly (p > 0.05). Our results suggest that captive white-handed gibbons are not opportunistic, but selective feeders with regard to
maximizing net gain of energy because only the content of carbohydrates, but not the contents of total energy, proteins, or
lipids significantly correlate with the displayed food preferences. Further, the results suggest that captive Hylobates lar, in contrast to their free-ranging conspecifics, do not display marked changes in their food selection across the day. 相似文献
17.
Larix principis-rupprechtii forest is an important vegetation formation and has a large distribution area in Luya Mountain Reserve, China. Spatial pattern
analysis on individual trees in different age-classes of Larix principis-rupprechtii was made in this paper. Here, we employed the technique of point pattern analysis, which could analyze patterns under all
scales along a gradient. It was based on spatial mapped points of individual distribution. The results of this study showed
that the densities of the five age-classes varied in the order: age-class 3 > age-class 4 > age-class 5 > age-class 2 > age-class
1. Although age-classes 1 and 2 have much fewer individuals than other three age-classes do, the population was stable at
present. However, it would be necessary to take some measures for improving population regeneration for a long-time view.
The individuals of all age-classes focused on clumping distribution in space; however, their distribution pattern varied with
the change of scale. This mainly depended on biological features of Larix principis-rupprechtii and forest environments, but it also meant that the scale was an important factor in controlling spatial distribution pattern
of tree individuals. The feature of clumping distribution became more significant with the increase of age. The relationships
between individuals in different age-classes were almost all significantly correlated with each other. These associations
became more significant within the older age-classes. This suggested that the individuals of different age-classes were interdistributed,
by which the population could get benefits in resource utilization. The technique of point pattern analysis is effective and
easy to be used in species pattern study. Its results are more closer to the reality, especially for community structure.
Translated from Acta Ecologica Sinica, 2004, 24(1): 35–40 [译自: 生态学报] 相似文献
18.
Tissue expression and cellular localization of phospholipid hydroperoxide glutathione peroxidase (PHGPx) mRNA in male mice 总被引:1,自引:0,他引:1
Baek IJ Seo DS Yon JM Lee SR Jin Y Nahm SS Jeong JH Choo YK Kang JK Lee BJ Yun YW Nam SY 《Journal of molecular histology》2007,38(3):237-244
Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is an ubiquitous antioxidant enzyme, but the exact expression pattern
in mammalian tissues is still unknown. The expression and cellular localization of PHGPx mRNA were examined in male mice using
real time-polymerase chain reaction and in situ hybridization techniques. The rank order of PHGPx mRNA expression across tissues exhibiting substantial levels of expression
was:testes ≫ heart > cerebrum ≥ ileum > stomach = liver = jejunum ≥ epididymis. In testes, PHGPx mRNA was highly expressed
in spermiogenic cells and Leydig cells. The signal was also expressed in the molecular layer, Purkinje cell layer, and white
matter of cerebellum, the pituicytes of neurohypophysis, the parafollicular cells and follicular basement membrane of thyroid,
the exocrine portion of pancreas, the tubular epithelium of kidney, the smooth muscle cells of arteries, and the red pulp
of spleen. In the gastrointestinal tract, PHGPx mRNA expression was mainly observed in the keratinized surface epithelium
of forestomach, the submucosal glands and serosa layers, and further the Paneth cells of intestines. PHGPx mRNA appeared to
be ubiquitously expressed in the parenchyma of heart, liver, and lung. These results indicate that PHGPx exhibits a cell-
and tissue-specific expression pattern in mice. 相似文献
19.
Papagianni M Boonpooh Y Mattey M Kristiansen B 《Journal of industrial microbiology & biotechnology》2007,34(4):301-309
Fed-batch culture is the mode of operation of choice in industrial baker’s yeast fermentation. The particular mode of culture,
operated at stable glucose and maltose concentration levels, was employed in this work in order to estimate important kinetic
parameters in a process mostly described in the literature as batch or continuous culture. This way, the effects of a continuously
falling sugar level during a batch process were avoided and therefore the effects of various (stable) sugar levels on growth
kinetics were evaluated. Comparing the kinetics of growth and the inhibition by the substrate in cultures grown on glucose,
which is the preferential sugar source for Saccharomyces cerevisiae, and maltose, the most common sugar source in industrial media for baker’s yeast production, a milder inhibition effect by
the substrate in maltose-grown cells was observed, as well as a higher yield coefficient. The observed sugar inhibition effect
in glucostat cultures was taken into account in modeling substrate inhibition kinetics. The inhibition coefficient K
i increased with increasing sugar concentration levels, but it appeared to be unaffected by the type of substrate and almost
equal for both substrates at elevated concentration levels. 相似文献
20.
K Tonosaki L M Beidler 《Comparative biochemistry and physiology. A, Comparative physiology》1989,94(4):603-605
1. Sugar best single chorda tympani nerve fiber of rat and hamster were tested with six sugars. 2. Fibers were selected for this experiment, only if they responded to 1.0 M sucrose or 1.0 M maltose and they responded poorly to 0.1 M NaCl. 3. In rat, some single fibers gave larger responses to maltose than to sucrose, while in hamster nearly all nerve fibers responded best to sucrose. 4. The order of effectiveness of sugars was maltose greater than fructose greater than or equal to lactose greater than sucrose greater than glucose greater than galactose in rat and sucrose greater than fructose greater than or equal to glucose greater than or equal to galactose greater than maltose greater than lactose in hamster. 相似文献