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1.
The harmful effects of surfactants to the environment are well known. We were interested in investigating their potential
toxicity in a pure culture of Acinetobacter junii, a phosphate (P)-accumulating bacterium. Results showed a high acute toxicity of sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium
bromide (HDTMA) against A. junii. The estimated EC50 values of the HDTMA for the inhibition of CFUs in the pure culture of A. junii was 3.27 ± 1.12 × 10−7 mol L−1 and for the inhibition of the P-uptake rates 2.47 ± 0.51 × 10−6 mol L−1. For SDS, estimated EC50 values for the inhibition of CFUs in the pure culture of A. junii was 5.00 ± 2.95 × 10−6 mol L−1 and for the inhibition of the P-uptake rates 3.33 ± 0.96 × 10−4 mol L−1. The obtained EC50 values in the standardised yeast toxicity test using Saccharomyces cerevisiae were 3.03 ± 0.38 × 10−4 and 4.33 ± 0.32 × 10−5 mol L−1 for SDS and HDTMA, respectively. These results emphasized the need to control concentrations of surfactants entering the
activated sludge system. The negative effects of these toxicants could greatly decrease populations of P-accumulating bacteria,
as well as eukaryotic organisms, inhabiting activated sludge systems, which in turn could result in the decrease of the system
efficiency. 相似文献
2.
Allison A. Welder Roberta Grant June Bradlaw Daniel Acosta 《In vitro cellular & developmental biology. Animal》1991,27(12):921-926
Summary Tricyclic antidepressants (TCAs) are currently used in the treatment of mental depression and nocturnal enuresis. Clinically,
these drugs are useful; however, cardiotoxicity can occur even with therapeutic dosages. For example, TCAs are known to alter
myocardial function, induce arrhythmias, and produce heart block in individuals with a normal cardiovascular history. The
present study was undertaken to establish a culture system of spontaneously contracting adult primary myocardial cells for
toxicologic testing and to examine their contractility, morphology, and lactate dehydrogenase release (LDH) after treatment
with one of the most cardiotoxic TCAs, amitriptyline. Primary myocardial cell cultures were obtained from approximately 60-
to 90-day-old Sprague-Dawley rats. After the cells had been grown in culture for 11 days, they were treated with amitriptyline
(1 × 10−3, 1 × 10−4, and 1 × 10−5
M) for 2 to 24 h. The highest concentration of amitriptyline (1 × 10−3
M) completely destroyed the cardiac muscle cells. In addition to moderate and severe vacuole, granule, and pseudopodia formation,
all contractile activity was inhibited as early as 2 h after exposure to the intermediate concentration of 1 × 10−4
M amitriptyline. Significant LDH release did not occur until 8 h after treatment with this intermediate concentration. Even
though there was no significant LDH release at all 3 time points tested, there was a 50% decrease in beating activity (154±9
to 77±5 beats/min) and initiation of vacuole formation by 2 h with the lowest concentration of amitriptyline (1 × 10−5
M). This study presents a new apparatus for the isolation of adult cardiac myocytes for the establishment of primary cell cultures
for toxicologic testing. Furthermore, these data demonstrate that amitriptyline induces a concentration- and time-dependent
cardiotoxic profile in a model of spontaneously contracting adult cardiac muscle cells in culture. 相似文献
3.
Julio C. Davila Chandrasekara G. Reddy Patrick J. Davis Daniel Acosta 《In vitro cellular & developmental biology. Plant》1990,26(5):515-524
Summary The present study was undertaken to assess and compare the toxic effects of papaverine hydrochloride and its metabolites.
Primary cell cultures of rat hepatocytes were treated with papavarine (papaver), 3′-O-desmethyl (3′-OH), 4′-O-desmethyl (4′-OH),
and 6-O-desmethyl (6-OH) papaverine at 1×10−5, 1×10−4, and 1×10−3
M for 4,8, 12, and 24-h periods. Cell injury was determined by: a) cell viability using the trypan blue exclusion test; b)
cytosolic enzyme leakage of lactate dehydrogenase and aspartate aminotransferase; c) morphologic alterations; and d) lactate:
pyruvate (L:P) ratios. Cell cultures showed concentration-and time-dependent responses. For example, a decrease in cell viability
and an increase in enzyme leakage were observed after cell treatment with 1×10−4 and 1×10−3
M papaver for 8 h; 1×10−3
M 6-OH papaverine for 8 h and 1×10−4
M for 24 h; and 1×10−3
M 4′-OH papaverine for 24 h (P<0.05). Furthermore, changes in morphology correlated to cell viability and enzyme release in those cultures treated with
papaver, 4′-OH and 6-OH papaverine. Some of these changes included size deformation, cell detachment from the dishes, and
cell necrosis. On the other hand, an increase in L:P ratios (P<0.05) was detected with papaver as early as 8 h with 1×10−4 and 1×10−3
M and 12 h with 1×10−5
M; 6-OH showed an increase, in L:P ratios at 8 h with 1×10−3
M and 12 h with 1×10−4
M; these changes were evident with 4′-OH at 12 h with 1×10−3
M. In contrast, cells treated with 3′-OH papaverine did not show significant damage with any time period and concentration
used in this study. The results of this study indicate that papaverine-derived metabolites are less cytotoxic than its parent
compound, papaver. The toxicity was ranked as follows: papaver>6-OH>4′-OH>−3′-OH.
This work was supported in part by grant ES04200-02 from the National Institute of Environmental Health Sciences, Bethesda,
MD.
Presented in part at the fall ASPET meeting in Salt Lake City, August, 1989. Daniel Acosta is a Burroughs Wellcome Scholar
in Toxicology. 相似文献
4.
The clastogenic effect ofN-methyl-N′-nitro-N-nitrosoguanidine (MNNG) in Chinese hamster ovary (CHO) cells and its modulation by Na2SeO3 and caffeine were studied by metaphase analysis of chromosome aberrations (CA) as well as by measuring the formation and
repair of single-strand (ss) DNA breaks employing hydroxylapatite chromatography. Treatment of CHO cells with MNNG (1.25 or
2.5 × 10-5M) for 3 h caused CA in 11 and 19% of metaphases scored, respectively. Pretreatment of cells with Na2SeO3 (1–5 μg/mL) or caffeine (0.2–2.0 mg/mL) for 2 h resulted in a 2–3.5-fold increase of CA frequency. Addition of both modulators
during the mutagen exposure tended to cause a slight inhibition of clastogenic activity of MNNG (1.25 × 10−5
M) or had no effect on CA number when MNNG was used at a concentration of 2.5 × 10−5M. Posttreatment of CHO cells with Na2SeO3 for 20 h after MNNG was ineffective in influencing the number of metaphases with CA, whereas, at these conditions, caffeine
enhanced up to 6-7-fold the clastogenic activity of MNNG. Addition of both modulators during the whole experiment, 2 h pretreatment
included, resulted in a further significant increase of CA frequency up to the total pulverization of chromosomes in all metaphases
scored. The coclastogenic effect of caffeine was greater in this case. The enhancement of chromosome-damaging activity of
MNNG by selenite and caffeine was better expressed when this carcinogen was applied at the higher concentration used. An additive
coclastogenic effect was observed in CHO cells treated simultaneously with Na2SeO3 and caffeine plus MNNG. In addition, the treatment of CHO cells with MNNG (5 × 10−6
M) caused a rapid increase of ssDNA breaks number reaching maximal values after 30–45 min. However, up to 50–60% of MNNG-induced
ssDNA breaks were repaired during the first 60–150 min after the mutagen exposure. The 2 h pretreatment of CHO cells with
Na2SeO3 (2 μg/mL) or the addition of this trace element after MNNG had no effect on formation and repair of MNNG-induced ssDNA breaks.
The coclastogenic effect of Na2SeO3 in CHO cells treated with MNNG was not directly linked to the induction and disappearance of ssDNA breaks measured by hydroxylapatite
chromatography. 相似文献
5.
Serge Ostrovidov Patricia Franck Josette Capiaumont Brigitte Dousset Francine Belleville 《In vitro cellular & developmental biology. Animal》1998,34(3):259-264
Summary The effect of low concentrations of hydrogen peroxide (H2O2) (5 × 10−7−9.5 × 10−7
M) on cell growth and antibody production was investigated with murine hybridoma cells (Mark 3 and anti-hPL) in culture. Cell
growth, measured by flow cytometry with morphological parameters, was significantly stimulated by H2O2 (8 × 10−7
M) but H2O2 concentration of 7 × 10−6
M and above increased cell death. H2O2 stimulation of antibody production was nonsignificant. The metabolism of cells treated with 8 × 10−7 or 1 × 10−5
M H2O2 was similar to that of the control in terms of glucose and glutamine consumption, lactate and ammonia production, and amino
acid concentrations in the medium. The concentrations of lactate dehydrogenase, a marker of cell death, in test and control
cells were similar. However, concentrations of intracellular free radicals measured by flow cytometry with dihydrorhodamine
123 (DHR 123) and dichlorofluorescein diacetate (DCFH-DA) as fluorochromes were different. The reactive oxygen species content
of cells in 8 × 10−7
M H2O2 was similar to that of the controls, but there was a sudden, marked production of superoxide anions (detected with DHR 123)
and H2O2 or peroxides (detected with DCFH-DA) by cells incubated with 1 × 10−5
M H2O2 which increased with increasing H2O2 until cell death. 相似文献
6.
Jasna Hrenovic Tomislav Ivankovic Lavoslav Sekovanic Mirela Rozic 《Central European Journal of Biology》2008,3(2):143-148
The antibacterial effect of cationic surfactants against the pure culture of phosphate (P)-accumulating bacterium Acinetobacter junii was investigated. The estimated EC50 values of the N-dodecylpyridinium chloride (DPC) for growth inhibition was 1.4±0.5 × 10−6 mol L−1 and for the inhibition of the P-uptake rates 7.3±2.6 × 10−5 mol L−1. The estimated EC50 values of the N-cetylpyridinium chloride (CPC) for growth inhibition was 4.9±1.3 × 10−7 mol L−1 and for the inhibition of the P-uptake rates 7.7±2.9 × 10−6 mol L−1. This suggests the importance of controlling the amounts of cationic surfactants in influent of the wastewater treatment
systems in order to avoid the possible failure of the biological P removal from wastewaters. 相似文献
7.
We investigated the effects of limiting (1.96 × 10−9 mol l−1 total Cu, corresponding to pCu 14.8; where pCu = −log [Cu2+]) and toxic Cu concentrations up to 8.0 × 10−5 mol l−1 total Cu (equivalent to pCu 9.5) on growth rates and photosynthetic activity of exponentially grown Phaeocystis cordata, using batch and semi-continuous cultures. With pulse amplitude modulated (PAM) fluorometry, we determined the photochemical
response of P. cordata to the various Cu levels, and showed contrasting results for the batch and semi-continuous cultures. Although maximum photosystem
II (PSII) quantum yield (ΦM) was optimal and constant in the semi-continuous P. cordata, the batch cultures showed a significant decrease in ΦM with culture age (0–72 h). The EC50 for the batch cultures was higher (2.0 × 10−10 mol l−1, pCu9.7), than that for the semi-continuous cultures (6.3 × 10−11 mol l−1, pCu10.2). The semi-continuous cultures exhibited a systematic and linear decrease in ΦM as Cu levels increased (for [Cu2+] < 1.0 × 10−12 mol l−1, pCu12.0), however, no effect of high Cu was observed on their operational PSII quantum yield (Φ′M). Similarly, semi-continuous cultures exhibited a significant decrease in ΦM, but not in Φ′M, because of low-Cu levels. Thus, Cu toxicity and Cu limitation damage the PSII reaction centers, but not the processes downstream
of PSII. Quenching mechanisms (NPQ and Q
n) were lower under high Cu relative to the controls, suggesting that toxic Cu impairs photo-protective mechanisms. PAM fluorometry
is a sensitive tool for detecting minor physiological variations. However, culturing techniques (batch vs. semi-continuous)
and sampling time might account for literature discrepancies on the effects of Cu on PSII. Semi-continuous culturing might
be the most adequate technique to investigate Cu effects on PSII photochemistry. 相似文献
8.
Culture of human hepatocytes from small surgical liver biopsies. Biochemical characterization and comparison with in vivo 总被引:4,自引:0,他引:4
M. José Gómez-Lechón Pilar López Teresa Donato Angel Montoya Amparo Larrauri Patricia Giménez Ramón Trullenque Ricardo Fabra José V. Castell 《In vitro cellular & developmental biology. Plant》1990,26(1):67-74
Summary High yields of human hepatocytes (up to 23×106 viable cells/g) were obtained from small surgical liver biopsies (1 to 3 g) by a two-step collagenase microperfusion method.
Cell viability was about 95%, attachment efficiency of hepatocytes seeded on fibronectin-coated plates was 80% within 1 h
after plating, and cells survived for about 2 wk in serum-free Ham’s F12 containing 0.2% bovine serum albumin, 10−8
M insulin, and 10−8
M dexamethasone. To evaluate the metabolism of human hepatocytes in serum-free conditions, we measured their most characteristic
biochemical functions and compared them to those reported for human liver. After 24 h in culture, glycogen content was 1250±177
nmol glucose/mg cell protein and remained stable for several days. Gluconeogenesis from lactate in hormone-free media was
(3.50±0.17 nmol glucose·mg−1·min−1) similar to that reported for human liver. Insulin at 10−8
M activated glycolysis (×1.40) and glycogenesis (×1.34), and glucagon at 10−9
M stimulated gluconeogenesis (×1.35) and glycogenolysis (×2.18). Human hepatocytes synthesized albumin, transferrin, fibrinogen,
α1-antitrypsin, α1-antichymotrypsin, α1-acid glycoprotein, haptoglobin, α2-macroglobulin, and plasma fibronectin and excreted them to the culture medium. Maximum protein synthesis was stimulated by
10−9
M dexamethasone. Basal urea synthesis oscillated between 2.5 and 3.5 nmol·mg−1 cell protein·min−1, about 5 times the value estimated for human liver. Cytochrome P-450 decreased in culture but it was still 20% of freshly
isolated hepatocytes by Day 5 in culture. In addition, ethoxycumarin-O-deethylase and aryl hydrocarbon hydroxylase could be
induced in vitro by treatment with methyl cholanthrene. Glutathione levels were similar to those reported for human liver
(35 nmol·mg−1).
The results of our work show that adult human hepatocytes obtained from small surgical biopsies and cultured in chemically
defined conditions express their most important metabolic functions to an extent that is similar to that reported for adult
human liver. 相似文献
9.
In previous experiments, rates of picoplankton uptake into coral communities were controlled by sponge and ascidian biomass.
Those experimental communities, however, had relatively few sponges and ascidians. In contrast, turbulent transport of particles
into the momentum boundary layers can limit particle removal by layered, dense bivalve populations. In this study, the role
of water velocity in controlling particulate nutrient-uptake by rubble communities was evaluated, in which the rubble was
more completely covered by sponges and ascidians. Picoplankton uptake was proportional to concentration over a range of cell
concentrations from 3.0 × 105 to 9.5 × 105 heterotrophic bacteria ml−1, 4.1 × 104 to 1.2 × 105
Synechococcus sp. ml−1 and 6.3 × 103 to 1.8 × 104 picoeukaryotes ml−1. The first-order uptake rate constants, normalized to sponge and ascidian biomass, were similar to previous experimental
communities. Picoplankton uptake increased 1.6-fold over a 7-fold change in water velocity, 0.05–0.35 m s−1. This increase has been interpreted as a result of higher turbulent transport within the rough coral community (canopy),
as indicated by a 1.6-fold increase in the bottom friction with increasing water velocity. 相似文献
10.
Characteristics of the phytoplankton community and bioaccumulation of heavy metals during algal blooms in Xiangjiang River (Hunan,China) 总被引:2,自引:0,他引:2
The frequency of algal blooms has increased in the mid and downstream reaches of the Xiangjiang River (Hunan, China), one
of the most heavily polluted rivers in China. We identified the bloom-forming species in a bloom that occurred mid-late September
2010. In addition, we determined the extent of metal bioaccumulation in the algae and measured the toxicity of the algae using
a mouse bioassay. Water samples were collected at upstream (Yongzhou), midstream (Hengyang), and downstream (Zhuzhou, Xiangtan,
and Changsha) sites. The dominant species was Aulacoseira granulata, formerly known as Melosira granulata. The heaviest bloom occurred at Xiangtan and Changsha, where the number of A. granulata peaked at 1.3×105 filaments L−1 and chlorophyll a at 0.04 mg L−1. Concentrations of Al, Fe, and Mn were 4.4×103, 768.4, and 138.7 mg kg−1 dry weight in the phytoplankton. The bioaccumulation factor was 4.0×105, 7.7×105, and 3.2×103, respectively. The heavy metal Pb had the greatest tendency to bioaccumulate among the highly toxic heavy metals, with a
concentration of 19.2 mg kg−1 dry weight and bioaccumulation factor of 9.6×103. The mouse bioassay suggested the bloom was toxic. The LD50 was 384 mg kg−1 and all surviving mice lost weight during the first 72 h after exposure. Our results demonstrate that blooms of A. granulata in rivers contaminated with heavy metals pose a threat to freshwater ecosystems and human health. Thus, measures should be
taken to control eutrophication and heavy metal pollution in such rivers. 相似文献
11.
R. Goulder 《Current microbiology》1979,2(6):365-368
Specific activity of aquatic bacteria, which indicates average heterotrophic activity per bacterial cell, was determined asV
max
per bacterium and turnover rate per bacterium for glucose mineralization at different sites (river and estuary) in north
Humberside, northeast England.V
max
per bacterium ranged from 0.05×10−13 to 52.2×10−13 mg/h and turnover rate per bacterium from 0.05×10−8 to 88.3×10−8 ml/h. Highest mean values were found at river sites and the lowest at an outer estuary site, although there was considerable
variation at each site and ranges from all sites overlapped. Also, ranges ofV
max
per bacterium from Humberside sites in general overlapped published ranges for sites in other geographical areas.V
max
per bacterium and turnover rate per bacterium were significantly correlated with some environmental variables, which suggests
that they are of ecological significance. 相似文献
12.
Surface inoculation dose–response and time–response bioassays and detached fruit bioassays were conducted with a novel South
African isolate of the Cryptophlebia leucotreta granulovirus (CrleGV-SA) against Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Noctuidae) neonate larvae. LC50 and LC90 values were estimated to be 4.095 × 103 and 1.185 × 105 OBs ml−1, respectively. LT50 and LT90 values were estimated to be 4 days 22 h and 7 days 8 h, respectively, categorising the virus as a fast or type 2 granulovirus.
There was a conspicuous difference in behaviour between larvae on inoculated diet and untreated diet, resulting in a significant
reduction in penetration of diet. Bioassays on detached Navel oranges revealed LC50 and LC90 values of 9.310 × 107 and 1.515 × 109 OBs ml−1, when using data on numbers of larvae per fruit rather than on numbers of infested fruit. Field trials will be conducted. 相似文献
13.
The relationship between scale and body growth for emigrating Atlantic salmon, Salmo salar, smolts was previously not understood and therefore was examined in this study using mark-recapture techniques. The size
of smolts at time of recapture was significantly greater than when marked (P = 0.0002). The growth in length of smolts emigrating 5 km over an average of 20 days was 7.7 ± 6.1 mm per day. Instantaneous
somatic growth (G
body) ranged from 7.0 × 10−4 to 5.1 × 10−3 (mean = 2.7 × 10−3 ± 1.3 × 10−3). The mean number of plus growth circuli present per scale was significantly greater for smolts when recaptured compared
to when marked (P = 0.0014). The instantaneous growth rate of scales (G
scale) ranged from 1.4 × 10−3 to 11.5 × 10−3 (mean = 6.6 × 10−3 ± 4.3 × 10−3). The relationship between body size and scale radius showed positive allometry rather than isometry. The relationship of
G
scale with G
body showed positive allometry indicating that scales grew at a slightly faster rate than the body during the emigratory period. 相似文献
14.
Lens Major Intrinsic Protein (MIP) is a member of a family of membrane transport proteins including the Aquaporins and bacterial
glycerol transporters. When expressed in Xenopus oocytes, MIP increased both glycerol permeability and the activity of glycerol kinase. Glycerol permeability (p
Gly
) was 2.3 ± 0.23 × 10−6 cm sec−1 with MIP vs. 0.92 ± 0.086 × 10−6 cm sec−1 in control oocytes. The p
Gly
of MIP was independent of concentration from 5 × 10−5 to 5 × 10−2
m, had a low temperature dependence, and was inhibited approximately 90%, 80% and 50% by 1.0 mm Hg++, 0.2 mm DIDS (diisothiocyanodisulfonic stilbene), and 0.1 mm Cu++, respectively. MIP-enhanced glycerol phosphorylation, resulting in increased incorporation of glycerol into lipids. This
could arise from an increase in the total activity of glycerol kinase, or from an increase in its affinity for glycerol. Based
on methods we present to distinguish these mechanisms, MIP increased the maximum rate of phosphorylation by glycerol kinase
(0.12 ± 0.03 vs. 0.06 ± 0.01 pmol min−1 cell−1) without changing the binding of glycerol to the kinase (K
M
∼ 10 μm).
Received: 23 May 1997/Revised: 4 August 1997 相似文献
15.
Kabir ME Krishnaswamy S Miyamoto M Furuichi Y Komiyama T 《Applied microbiology and biotechnology》2011,90(2):553-564
Phage-display and competitive panning elution leads to the identification of minimum-sized antigen binders together with conventional
antibodies from a mouse cDNA library constructed from HM-1 killer toxin neutralizing monoclonal antibody (nmAb-KT). Antigen-specific
altered camelid-like single-domain heavy chain antibody (scFv K2) and a conventional antibody (scFv K1) have been isolated
against the idiotypic antigen nmAb-KT. The objectives of the study were to examine (1) their properties as compared to conventional
antibodies and also (2) their antifungal activity against different pathogenic and non-pathogenic fungal species. The alternative
small antigen-binder, i.e., the single-domain heavy chain antibody, was originated from a conventional mouse scFv phage library
through somatic hyper-mutation while selection against antigen. This single-domain antibody fragment was well expressed in
bacteria and specifically bound with the idiotypic antigen nmAb-KT and had a high stability and solubility. Experimental data
showed that the binding affinity for this single-domain antibody was 272-fold higher (K
d = 1.07 × 10−10 M) and antifungal activity was three- to fivefold more efficient (IC50 = 0.46 × 10−6 to 1.17 × 10−6 M) than that for the conventional antibody (K
d = 2.91 × 10−8 M and IC50 = 2.14 × 10−6 to 3.78 × 10−6 M). The derived single-domain antibody might be an ideal scaffold for anti-idiotypic antibody therapy and the development
of smaller peptides or peptide mimetic drugs due to their less complex antigen-binding site. We expect that such single-domain
synthetic antibodies will find their way into a number of biotechnological or medical applications. 相似文献
16.
To develop an integrated process of CO2-fixation and H2 photoproduction by marine green microalga Platymonas subcordiformis, the impact of algal cells grown in CO2-supplemented air bubble column bioreactor was investigated on H2 photoproduction regulated by carbonylcyanide m-chlorophenylhrazone. Highest cell growth (3.85 × 106 cells ml−1), starch content (0.25 ± 0.08 mg per 106 cells) and hydrogen production (50 ± 3 ml l−1) were achieved at 3% CO2-supplemented culture, which are respectively 1.4, 2.1, 1.5-fold of the air-supplemented culture. Improved H2 production correlated well with the increase in starch accumulation. In this process, the algal cells have been recycled
for stable H2 production of 40–50 ml l−1 over five cycles. 相似文献
17.
Schiff Leonard J. Moore Steven J. 《In vitro cellular & developmental biology. Plant》1985,21(12):688-692
Summary The ability of cyclic AMP-elevating agents to induce normal differentiation has been investigated in retinoid-deficient hamster
tracheal epithelium in organ culture. Dibutyryl cAMP (dbcAMP) and other cAMP-regulating agents alone caused disappearance
of keratin and regeneration of normal mucociliary epithelium in retinoid-deficient cultures. Incubation of retinoid-deficient
cultures with dbcAMP, isoproterenol, and cholera toxin (CT) (without addition of exogenous retinoid) reversed keratinization
in a dose-dependent manner. The ED50 of cultures treated with dbcAMP was 4×10−6
M; ED50 of isoproterenol was 7×10−5
M; and CT, 0.6 μg/ml. Phosphodiesterase inhibitors and other cAMP analogs were inactive. Dibutyryl cAMP in combination with
theophylline enhanced normal differentiation. Retinoid-deficient tracheas pretreated for 20 h with 10−9
M all-trans-retinoic acid (RA) responded to 10−6
M dbcAMP by potentiating normal differentiation; this concentration of dbcAMP alone was inactive. Isoproterenol showed a similar
response but to a lesser degree. These cAMP-elevating agents applied in combination with theophylline did not increase activity.
This investigation was supported by National Cancer Institute Contract NO1-CP-31012. 相似文献
18.
Fabiana R. X. Batista Carlos A. Pereira Ronaldo Z. Mendon?a Angela M. Moraes 《Cytotechnology》2005,49(1):1-9
Animal cells can be cultured both in basal media supplemented with fetal bovine serum (FBS) and in serum-free media. In this
work, the supplementation of Grace’s medium with a set of nutrients to reduce FBS requirements in Spodoptera frugiperda (Sf9) cell culture was evaluated, aiming the production of Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) at a cost lower than those for the production using Sf900 II medium. In Grace’s medium supplemented
with glucose, Pluronic F68 (PF68) and yeast extract (YE), the effects of FBS and milk whey ultrafiltrate (MWU) on cell concentration
and viability during midexponential and stationary growth phase were evaluated. In spite of the fact that FBS presented higher
statistical effects than MWU on all dependent variables in the first cell passage studies, after cell adaptation, AgMNPV polyhedra
production was comparable to that in Sf900 II. Batch cultivation in Grace’s medium with 2.7 g l−1 glucose, 8 g l−1 YE and 0.1% (w/v) PF68 supplemented with 1% (w/v) MWU and 3% (v/v) FBS increased viable cell concentration to about 5-fold
(4.7×106 cells ml−1) when compared to Grace’s containing 10% (v/v) FBS (9.5×105 cells ml−1). AgMNPV polyhedra (PIBs) production was around 3-fold higher in the MWU supplemented medium (1.6×107 PIBs ml−1) than in Grace’s medium with 10% FBS (0.6×107 PIBs ml−1). This study therefore shows a promising achievement to significantly reduce FBS concentration in Sf9 insect cell media,
keeping high productivity in terms of cell concentration and final virus production at a cost almost 50% lower than that observed
for Sf900 II medium.
C.A. Pereira is recipient of a CNPq fellowship. 相似文献
19.
Filiberto Cimino Cinzia Traboni Alfredo Colonna Paola Izzo Francesco Salvatore 《Molecular and cellular biochemistry》1981,40(2):95-104
Summary A fast method for a single-step fractionation of a number of tRNA methyltransferases fromSalmonella typhimurium is described. The method basically consists of ion-exchange chromatography on a phosphocellulose column and permits the separation
of the enzymes forming mt6A, m1G, m5U, m7G. The enzyme fractions appear sufficiently purified to allow the estimation of some molecular and kinetic properties. The
apparent KM for adenosylmethionine range between 1.5 to 3.2×10−5 M, whereas KM for undermethylated tRNA range between 3.1×10−5 M to 3.1×10−4 M. Glycerol gradient determination indicates the following Mr for the native proteins: 25×103, 40×103, 50×103 and 65×103 for m7G-, mt6A-, m1G- and m5U-forming enzymes, respectively. A complete analysis of methylated nucleosides formedin vivo inS. typhimurium has been obtained: it also allowed us to infer the pattern of the various tRNA methyltransferases for this prokaryote. The
tRNA methyltransferase forming mt6A has been isolated for the first time from any type of cell. 相似文献
20.
Four species of brown seaweeds, namely Sargassum baccularia, Sargassum binderi, Sargassum siliquosum and Turbinaria conoides, harvested from Port Dickson, Negeri Sembilan, Malaysia were analysed for ash content, alginate yield and alginate properties.
Seaweeds calcined at 450°C were found to have low amount of non-combustible residue as these were not contaminated by calcareous
animals. Alginate was extracted from these seaweeds by two methods: hot and cold. In the hot method, the storing time was
3 h and the processing temperature was 50°C, whilst in the cold method, the sample was stored overnight at room temperature.
Higher yield of alginate was obtained by the hot method compared to the cold method, but alginate extracted by the cold method
gave higher molecular weight. In the hot method, 49.9% of alginate was extracted from S. siliquosum, followed by T. conoides (41.4%), S. binderi (38.9%) and S. baccularia (26.7%). Alginate extracted from T. conoides has an average molecular weight, M
w, of 8.06 × 105 g mol−1, whereas alginate from S. siliquosum was the lowest in M
w (4.81 × 105 g mol−1) when the extraction was done at room temperature. Alginate extracted from S. baccularia was found to be very heat-sensitive. Its M
w has dropped more than 83%, from 7.52 × 105 to 1.23 × 105 g mol−1, when the extraction temperature was raised. The effect of heat on the extent of depolymerisation of the alginate molecule
of the other three brown seaweed species was less significant, with decrease in molecular weight ranging between 13% and 16%. 相似文献