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1.
The Capacity of Manno-Oligosaccharides,Thermolysed Yeast and Active Yeast to Attenuate Aflatoxicosis
Sampaio Baptista Antonio Horii Jorge Antonia Calori-Domingues Maria Micotti da Glória Eduardo Mastrodi Salgado Jocelem Roberto Vizioli Mário 《World journal of microbiology & biotechnology》2004,20(5):475-481
This study assessed the ability of thermolysed, active yeast, Saccharomyces cerevisiae, and manno-oligosaccharides, to reduce the effects of aflatoxins in animals. A basic ration was developed with six different formulations. Each formulation was considered a treatment. The treatments were: an aflatoxin-free formulation, an aflatoxin control (400 g kg–1) and four aflatoxin-supplemented formulations. The supplements were 0.1 and 0.2% manno-oligosaccharides, 1% thermolysed yeast and 1% dehydrated active yeast. The experiment was randomly designed and had five repetitions per treatment. The feed was contaminated with aflatoxins from naturally contaminated peanuts. A bioassay with Wistar rats was conducted after 28 days. The aflatoxin toxicity was evaluated by weighing body organs (heart, kidneys and liver) and by analysing the liver tissue of the animals. No significant differences were observed for the weights of the body organs from the animals fed with the different rations. However, the analysis of the liver tissue showed animals fed with 400 g of aflatoxin kg–1, and those fed diets with aflatoxin amended with either manno-oligosaccharides or with thermolysed yeast had clear signs of toxicity and damage, while those fed with dehydrated active yeast showed less intense toxicity and less liver damage. Therefore, the thermolysed yeast and manno-oligosaccharides did not suppress damage to liver tissue caused by aflatoxins, while active yeast reduced the aflatoxin symptoms in the hepatocytes. 相似文献
2.
Aflatoxins are produced as secondary metabolites under conducive climatic conditions by Aspergillus flavus. The incidence of aflatoxin varies with environmental conditions, genotype, and location. An expanded understanding of the
interaction of the plant, fungus, and weather conditions is needed to further elucidate the field infection process of maize
by A. flavus and subsequent aflatoxin contamination. One of the problems in evaluating maize hybrids for resistance to kernel infection
and aflatoxin contamination is identifying a time period and environmental conditions that are most advantageous. Three maize
genotypes (Pioneer Brand 3223, Mo18W × Mp313E, and Mp313E × Mp420) were evaluated from 1998 to 2002 in response to A. flavus inoculation and aflatoxin contamination and weather conditions favorable for aflatoxin contamination were identified. The
highest aflatoxin levels were observed in 1998 and 2000 (1186 and 901 ng g−1; P < 0.0001); while the lowest levels were detected in 1999 (39 ng g−1). Pioneer 3223 had significantly higher levels (1198 ng g−1) than Mp313E × Mp420 (205 ng g−1), and Mo18W ×Mp313E (161 ng g−1; P < 0.0001). The hybrids had six weather-related variables in common that were positively correlated with aflatoxin accumulation.
Four of these occurred during 65–85 days after planting and were temperature-related. These results suggest that regardless
of the hybrid’s maturity or physiological development, the time from 65 to 85 days after planting may be indicative of a period
of stress which leads to greater aflatoxin accumulation at harvest.
The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
3.
William E. Walton 《Journal of vector ecology》2016,41(1):80-89
The developmental time and survival to eclosion of Anopheles hermsi Barr & Guptavanij fed monotypic and mixed diets of ten food types were examined in laboratory studies. Larvae fed monotypic diets containing animal detritus (freeze‐dried rotifers, freeze‐dried Daphnia pulicaria, and TetraMin® fish food flakes) and the mixotrophic protistan Cryptomonas ovata developed faster and survived better than larvae that were fed other monotypic diets. Survival to adulthood of larvae fed several concentrations of the diatom Planothidium (=Achnanthes) lanceolatum was poor (<13%) and larval development time was approximately twice that of larvae fed TetraMin® fish food flakes, the standard laboratory diet. Larvae fed monotypic diets containing prokaryotes (bacteria [Bacillus cereus] and cyanobacteria [Oscillatoria prolifera]) and brewer's yeast (Saccharomyces cerevisiae) failed to survive beyond the 1st and 2nd instar, respectively. Larvae fed only chlorophytes, single‐celled Chlamydomonas reinhardtii and filamentous Spirogyra communis, failed to complete larval development, regardless of the concentration tested. Cohorts fed a combination of food types (mixed diets) usually developed better than cohorts fed monotypic diets. Food types that failed to support complete development when fed alone often facilitated development to adulthood when fed in combination with food types containing >1% C20 polyunsaturated fatty acids as total fat, but regardless of essential fatty acid content, algae that produced mucilage and filaments that sank out of the feeding zone were poor quality diets. 相似文献
4.
A mesophilic wine yeast, Saccharomyces cerevisiae CSIR Y217 K
–
R
– was subjected to the K2 killer effect of Saccharomyces cerevisiae T206 K
+
R
+ in a liquid grape medium. The lethal effect of the K2 mycoviral toxin was confirmed by methylene blue staining. Scanning electron microscopy of cells from challenge experiments revealed rippled cell surfaces, accompanied by cracks and pores, while those unaffected by the toxin, as in the control experiments, showed a smooth surface. Transmission electron microscopy revealed that the toxin damaged the cell wall structure and perturbed cytoplasmic membranes to a limited extent. 相似文献
5.
Citric acid production from sucrose using a recombinant strain of the yeast Yarrowia lipolytica 总被引:1,自引:0,他引:1
Förster A Aurich A Mauersberger S Barth G 《Applied microbiology and biotechnology》2007,75(6):1409-1417
The yeast Yarrowia lipolytica is able to secrete high amounts of several organic acids under conditions of growth limitation and carbon source excess.
Here we report the production of citric acid (CA) in a fed-batch cultivation process on sucrose using the recombinant Y. lipolytica strain H222-S4(p67ICL1) T5, harbouring the invertase encoding ScSUC2 gene of Saccharomyces cerevisiae under the inducible XPR2 promoter control and multiple ICL1 copies (10–15). The pH-dependent expression of invertase was low at pH 5.0 and was identified as limiting factor of the CA-production
bioprocess. The invertase expression was sufficiently enhanced at pH 6.0–6.8 and resulted in production of 127–140 g l−1 CA with a yield Y
CA of 0.75–0.82 g g−1, whereas at pH 5.0, 87 g l −1 with a yield Y
CA of 0.51 gg−1 were produced. The CA-productivity Q
CA increased from 0.40 g l −1 h−1 at pH 5.0 up to 0.73 g l −1 h−1 at pH 6.8. Accumulation of glucose and fructose at high invertase expression level at pH 6.8 indicated a limitation of CA
production by sugar uptake. The strain H222-S4(p67ICL1) T5 also exhibited a gene–dose-dependent high isocitrate lyase expression
resulting in strong reduction (<5%) of isocitric acid, a by-product during CA production. 相似文献
6.
Biological decontamination of mycotoxins using microorganisms is one of the well known strategies for the management of mycotoxins
in foods and feeds. Among the different potential decontaminating microorganisms,Saccharomyces cerevisiae and lactic acid bacteria represent unique groups, which are widely used in food fermentation and preservation. The aim of
this study was to determine the influence of spontaneous fermentation with the use of probiotic bacteria and yeast (Lactobacillus paracasei/casei ŁOCK 0920,L. brevis ŁOCK 0944,L. plantarum ŁOCK 0945,Saccharomyces cerevisiae ŁOCK 0142), on reduction of sum of aflatoxines (B1, B2, G1, G2) and ochratoxin A concentration during fermentation and the microflora pattern during fermentaton. The probiotic bacteria
and yeast applied creates a starter culture for flour fermentation that has a stable feature of detoxication of aflatoxines
and especially ochratoxin A.
Presented at the 28th Mykotoxin-Workshop, Bydgoszcz, Poland, May 29–31, 2006 相似文献
7.
Experiments were conducted in order to observe the effect of five diets on the population development of the rotiferBrachionus plicatilis Müller under laboratory conditions. Diets were based on baker’s yeast (Saccharomyces cerevisiae) and the algaeTetraselmis suecica andIsochrysis galbana, mixed, or as simple diets. Growth rates, fecundity and biometric parameters were studied for 15 days. The cultures were
divided in a logarithmic phase and a harvesting phase. Rotifers fed onTetraselmis, alone or mixed with yeast orIsochrysis, gave good performances with the best results in all the parameters studied. Average growth rates in all diets were similar
during the exponential phase, with values ranging from 0.72 (Tetraselmis andTetraselmis + yeast) to 0.47 (yeast). During the harvesting phase there were high differences between diets, with rates highly reduced
in the yeast-group (0.17) and good rates whenTetraselmis was ingested (0.65–0.51). This alga had a positive influence on the rotifers, increasing individual growth and fecundity. 相似文献
8.
Carvalho RS Gomes LH Gonzaga do P Filho L Tavares FC 《Applied microbiology and biotechnology》2008,77(5):1131-1137
Saccharomyces cerevisiae hexokinase-less strains were produced to study the production of ethanol and fructose from sucrose. These strains do not
have the hexokinases A and B. Twenty-three double-mutant strains were produced, and then, three were selected for presenting
a smaller growth in yeast extract–peptone–fructose. In fermentations with a medium containing sucrose (180.3 g L−1) and with cell recycles, simulating industrial conditions, the capacity of these mutant yeasts in inverting sucrose and fermenting
only glucose was well characterized. Besides that, we could also see their great tolerance to the stresses of fermentative
recycles, where fructose production (until 90 g L−1) and ethanol production (until 42.3 g L−1) occurred in cycles of 12 h, in which hexokinase-less yeasts performed high growth (51.2% of wet biomass) and viability rates
(77% of viable cells) after nine consecutive cycles. 相似文献
9.
Ghoneum M Badr El-Din NK Noaman E Tolentino L 《Cancer immunology, immunotherapy : CII》2008,57(4):581-592
This study was undertaken to evaluate the effectiveness and mechanisms of anti-tumor activity of Baker’s yeast, Saccharomyces cerevisiae, in immunocompetent mice. Swiss albino mice were inoculated intramuscularly in the right thigh with Ehrlich Ascites Carcinoma
(EAC) cells. At day 8, mice bearing Solid Ehrlich Carcinoma tumor (SEC) were intratumorally (IT) injected with killed S. cerevisiae (10 × 106 and 20 × 106 cells) for 35 days. Histopathology of yeast-treated mice showed extensive tumor degeneration, apoptosis, and ischemic (coagulative)
and liquefactive necrosis. These changes are associated with a tumor growth curve that demonstrates a significant antitumor
response that peaked at 35 days. Yeast treatment (20 × 106 cells) three times a week resulted in a significant decrease in tumor volume (TV) (67.1%, P < 0.01) as compared to PBS-treated mice. The effect was determined to be dependent on dose and frequency. Yeast administered
three and two times per week induced significant decrease in TV as early as 9 and 25 days post-treatment, respectively. Administration
of yeast significantly enhanced the recruitment of leukocytes, including macrophages, into the tumors and triggered apoptosis
in SEC cells as determined by flow cytometry (78.6%, P < 0.01) at 20 × 106 cells, as compared to PBS-treated mice (42.6%). In addition, yeast treatment elevated TNF-α and IFN-γ plasma levels and lowered
the elevated IL-10 levels. No adverse side effects from the yeast treatment were observed, including feeding/drinking cycle
and life activity patterns. Indeed, yeast-treated mice showed significant final body weight gain (+21.5%, P < 0.01) at day 35. These data may have clinical implications for the treatment of solid cancer with yeast, which is known
to be safe for human consumption. 相似文献
10.
Fermentation of high concentrations of lactose to ethanol by engineered flocculent Saccharomyces cerevisiae 总被引:1,自引:0,他引:1
The development of microorganims that efficiently ferment lactose has a high biotechnological interest, particularly for cheese
whey bioremediation processes with simultaneous bio-ethanol production. The lactose fermentation performance of a recombinant
Saccharomyces cerevisiae flocculent strain was evaluated. The yeast consumed rapidly and completely lactose concentrations up to 150 g l−1 in either well- or micro-aerated batch fermentations. The maximum ethanol titre was 8% (v/v) and the highest ethanol productivity
was 1.5–2 g l−1 h−1, in micro-aerated fermentations. The results presented here emphasise that this strain is an interesting alternative for
the production of ethanol from lactose-based feedstocks. 相似文献
11.
The relevance of oxidative stress in the production of aflatoxin and its precursors was examined in different mutants of Aspergillus parasiticus, which produce aflatoxin or its precursor intermediates, and compared with results obtained from a non-toxigenic strain.
In comparison to the non-toxigenic strain (SRRC 255), an aflatoxin producing strain (NRRL 2999) or mutants that accumulate
aflatoxin precursors such as norsolorinic acid (by SRRC 162) or versicolorin (by NRRL 6196) or O-methyl sterigmatocystin (by SRRC 2043) had greater oxygen requirements and higher contents of reactive oxygen species. These
changes were in the graded order of NRRL 2999 > SRRC 2043 > NRRL 6196 > SRRC 162 > SRRC 255, indicating incremental accumulation
of reactive oxygen species, being least in the non-toxigenic strain and increasing progressively during the ternary steps
of aflatoxin formation. Oxidative stress in these strains was evident by increased activities of xanthine oxidase and free
radical scavenging enzymes (superoxide dismutase and glutathione peroxidase) as compared to the non-toxigenic strain (SRRC
255). Culturing the toxigenic strain in presence of 0.1–10 μM H2O2 in the medium resulted in enhanced aflatoxin production, which could be related to dose-dependent increase in [14C]-acetate incorporation into aflatoxin B1 and increased acetyl CoA carboxylase activity. The combined results suggest that formation of secondary metabolites such
as aflatoxin and its precursors by A. parasiticus may occur as a compensatory response to reactive oxygen species accumulation. 相似文献
12.
Anjali Madhavan Sriappareddy Tamalampudi Aradhana Srivastava Hideki Fukuda Virendra S. Bisaria Akihiko Kondo 《Applied microbiology and biotechnology》2009,82(6):1037-1047
Previously, a Saccharomyces cerevisiae strain was engineered for xylose assimilation by the constitutive overexpression of the Orpinomyces xylose isomerase, the S. cerevisiae xylulokinase, and the Pichia stipitis SUT1 sugar transporter genes. The recombinant strain exhibited growth on xylose, under aerobic conditions, with a specific growth
rate of 0.025 h−1, while ethanol production from xylose was achieved anaerobically. In the present study, the developed recombinant yeast was
adapted for enhanced growth on xylose by serial transfer in xylose-containing minimal medium under aerobic conditions. After
repeated batch cultivations, a strain was isolated which grew with a specific growth rate of 0.133 h−1. The adapted strain could ferment 20 g l−1 of xylose to ethanol with a yield of 0.37 g g−1 and production rate of 0.026 g l−1 h−1. Raising the fermentation temperature from 30°C to 35°C resulted in a substantial increase in the ethanol yield (0.43 g g−1) and production rate (0.07 g l−1 h−1) as well as a significant reduction in the xylitol yield. By the addition of a sugar complexing agent, such as sodium tetraborate,
significant improvement in ethanol production and reduction in xylitol accumulation was achieved. Furthermore, ethanol production
from xylose and a mixture of glucose and xylose was also demonstrated in complex medium containing yeast extract, peptone,
and borate with a considerably high yield of 0.48 g g−1. 相似文献
13.
Shokrollahzadeh S Bonakdarpour B Vahabzadeh F Sanati M 《Journal of industrial microbiology & biotechnology》2007,34(1):17-25
The effect of phosphate (P
i
) concentration on the growth behavior of Saccharomyces cerevisiae strain CEN.PK113-5D in phosphate-limited batch and chemostat cultures was studied. The range of dilution rates used in the present study was 0.08–0.45 h−1. The batch growth of yeast cells followed Monod relationship, but growth of the cells in phosphate-limited chemostat showed change in growth kinetics with increasing dilution rates. The difference in growth kinetics of the yeast cells in phosphate-limited chemostat for dilution rates below and above approximately 0.2 h−1 has been discussed in terms of the batch growth kinetic data and the change in the metabolic activity of the yeast cells. Immunological detection of a C-terminally myc epitope-tagged Pho84 fusion protein indicated derepressive expression of the Pho84 high-affinity P
i
transporter in the entire range of dilution rates employed in this study. Phosphate transport activity mediated by Pho84 transporter was highest at very low dilution rates, i.e. 0.08–0.1 h−1, corresponding to conditions in which the amount of synthesized Pho84 was at its maximum. 相似文献
14.
Trophic patterns of omnivorous freshwater shrimps, Exopalaemon modestus and Macrobrachium nipponensis, were investigated in two shallow eutrophic lakes by using stable isotope analysis. δ15N and δ13C of M. nipponensis and E. modestus increased with increasing body weight, which might be attributed to larger individuals ingesting organisms that feed higher
up the food chain and/or increased assimilation of benthic food items with enriched isotopic signatures. Of the freshwater
shrimps occurring in the studied lakes, those from Lake Taihu had significantly elevated δ15N and δ13C values (4.3‰ and 1.8‰, respectively) compared with those from the less eutrophic Lake Chaohu, indicating that the isotopic
signature might partially reflect the trophic states of their habitats. Mixing model results suggested that the benthic food
web provides the primary carbon source for both shrimp species, and that E. modestus assimilated relatively more pelagic food sources than M. nipponensis in these lakes.
Handling editor: S. Wellekens 相似文献
15.
Lake Ellesmere (Te Waihora) is a nationally important coastal brackish lake in New Zealand, however degradation in water quality
and loss of submerged macrophytes over past decades have raised concerns in regards to the declining status of the lake’s
commercial and customary fisheries, predominantly targeted at shortfin eels (Anguilla australis). We investigated foodweb dynamics and trophic linkages to shortfin eels in Lake Ellesmere using a combination of abundance
assessments, dietary studies, and stable isotope analyses. Data from our study are compared with historical data sets on benthic
invertebrate community composition and shortfin eel diets to trace changes in the trophic linkages to top predators that have
occurred since the late 1960s. Stable isotope analyses indicate that the foodweb is predominantly driven by epipelic and phytoplankton
derived carbon sources, although it was difficult to discriminate between these two carbon pools because of wind-driven resuspension
of lake sediments. Comparison of our survey results with historical data sets indicates a clear shift in benthic biota from
being dominated by phytofaunal species such as Potamopyrgus antipodarum (comprising 90% of total invertebrate biomass) during the 1960s, to now being almost entirely comprised of subterranean species
such as Chironomus zealandicus and oligochaetes (together comprising 82% of total invertebrate biomass). This shift in benthic communities has resulted
in significant changes in the size-specific diet of juvenile shortfin eels (<400 mm) from those reported for Lake Ellesmere
during the mid 1970s, with Chironomus larvae now comprising 65% of the diets of juvenile eels, whereas historically P. antipodarum was the dominant food item (>30% of total biomass). This shift towards foraging on smaller sediment-dwelling species could
have implications for juvenile eel bioenergetics, and may help explain why juvenile shortfin growth rates have significantly
decreased in past decades. Juvenile shortfins now appear to switch to foraging on preyfish (mainly common bullies, Gobiomorphus cotidianus) at a smaller size (≈400 mm) than historically recorded (>500 mm). Dietary and stable isotope signatures indicated that small
shortfins (100–299 mm) have considerable overlap in trophic position (δ13C = −20.4‰, δ15N = 13.6‰) with common bullies (δ13C = −20.5‰, δ15N = 13.7‰), the dominant fish in Lake Ellesmere (92% of total abundance CPUE), potentially indicating that these two species
may directly compete for food resources. These findings again highlighted the importance of C. zealandicus in sustaining the fish populations of the lake.
Handling editor: S. Declerck 相似文献
16.
Apetroaie C Andersson MA Spröer C Tsitko I Shaheen R Jääskeläinen EL Wijnands LM Heikkilä R Salkinoja-Salonen MS 《Archives of microbiology》2005,184(3):141-151
Producers of cereulide, the emetic toxin of Bacillus cereus, are known to constitute a specific subset within this species. We investigated physiological and genetic properties of 24
strains of B. cereus including two high cereulide producers (600–1,800 ng cereulide mg−1 wet weight biomass), seven average producers (180–600 ng cereulide mg−1 wet weight biomass), four low cereulide producers (20–160 ng cereulide mg−1 wet weight biomass) and 11 non-producers representing isolates from food, food poisoning, human gut and environment. The
13 cereulide producers possessed 16S rRNA gene sequences identical to each other and identical to that of B. anthracis strains Ames, Sterne from GenBank and strain NC 08234–02, but showed diversity in the adk gene (two sequence types), in ribopatterns obtained with EcoRI and PvuII (three types of patterns), in tyrosin decomposition, haemolysis and lecithin hydrolysis (two phenotypes). The cereulide-producing
isolates from the human gut represented two ribopatterns of which one was novel to cereulide-producing B. cereus and two phenotypes. We conclude that the cereulide-producing B. cereus are genetically and biochemically more diverse than hitherto thought. 相似文献
17.
The aim of this study was to evaluate the MPK1 (SLT2) gene deletion upon filamentous growth induced by isoamyl alcohol (IAA) in two haploid industrial strains of Saccharomyces cerevisiae using oligonucleotides especially designed for a laboratory S. cerevisiae strain. The gene deletion was performed by replacing part of the open reading frames from the target gene with the KanMX gene. The recombinant strains were selected by their resistance to G418, and after deletion confirmation by polymerase chain
reaction, they were cultivated in a yeast extract peptone dextrose medium + 0.5% IAA to evaluate the filamentous growth in
comparison to wild strains. Mpk1 derivatives were obtained for both industrial yeasts showing the feasibility of the oligonucleotides especially designed
for a laboratory strain (Σ1278b) by Martinez-Anaya et al. (In yeast, the pseudohyphal phenotype induced by isoamyl alcohol
results from the operation of the morphogenesis checkpoint. J Cell Sci 116:3423–3431, 2003). The filamentation rate in these
derivatives was significantly lower for both strains, as induced by IAA. This drastic reduction in the filamentation ability
in the deleted strains suggests that the gene MPK1 is required for IAA-induced filamentation response. The growth curves of wild and derivative strains did not differ substantially.
It is not known yet whether the switch to filamentous growth affects the fermentative characteristics of the yeast or other
physiological traits. A genetically modified strain for nonfilamentous growth would be useful for these studies, and the gene
MPK1 could be a target gene. The feasibility of designed oligonucleotides for this deletion in industrial yeast strains is shown. 相似文献
18.
Duckworth AR Samples GA Wright AE Pomponi SA 《Marine biotechnology (New York, N.Y.)》2003,5(6):519-527
In vitro culture is one possible method for supplying sponge metabolites for pharmaceutical applications, but appropriate feeding regimens that maximize both growth and metabolite biosynthesis are largely unknown. According to the natural concentration (NC) of cells 1 to 50 µm in size that are available to wild Axinella
corrugata, we fed explants a multispecific diet of bacteria, microalgae, and yeast at 4 different concentrations: 1NC, 3NC, 5NC, and 5+1NC (the last consisted of 5 NC of bacteria and 1 NC of microalgae and yeast). Explants fed a 3NC diet had the best culture response, growing on average from 8.5 g to 10.3 g in 8 weeks, and showing a 110% increase in concentration (milligrams per gram of dry weight) of the antitumor compound stevensine. Stevensine production in 3NC explants, representing the total milligrams of metabolite per explant, increased by 157% over the study. Explants fed at 1NC had relatively stable weights, indicating that the diet met metabolic costs only. Explants fed at the two highest concentrations lost weight after 4 weeks, possibly because long-term high cell concentration blocked their aquiferous system, reducing their ability to feed efficiently. Stevensine production in explants fed the 1NC, 5NC, or 5+1NC diets were similar, and varied little from the initial amount. A separate experiment showed that the clearance rate for A. corrugata is similar between the examined food types and cell concentrations over 5 hours, averaging 766 ml h–1 g DW–1.Overall, this study demonstrates that relatively small changes in food abundance can greatly affect both sponge growth and metabolite biosynthesis. The good growth and increased production of the target metabolite stevensine for A. corrugata explants fed a 3NC diet suggests that in vitro culture is a viable method of supplying some sponge metabolites. 相似文献
19.
Mariya V. Kovaleva Evgeniya I. Sukhanova Tatyana A. Trendeleva Marina V. Zyl’kova Ludmila A. Ural’skaya Kristina M. Popova Nils-Erik L. Saris Renata A. Zvyagilskaya 《Journal of bioenergetics and biomembranes》2009,41(3):239-249
In this study we used tightly-coupled mitochondria from Yarrowia lipolytica and Dipodascus (Endomyces) magnusii yeasts, possessing a respiratory chain with the usual three points of energy conservation. High-amplitude swelling and collapse
of the membrane potential were used as parameters for demonstrating induction of the mitochondrial permeability transition
due to opening of a pore (mPTP). Mitochondria from Y. lipolytica, lacking a natural mitochondrial Ca2+ uptake pathway, and from D. magnusii, harboring a high-capacitive, regulated mitochondrial Ca2+ transport system (Bazhenova et al. J Biol Chem 273:4372–4377, 1998a; Bazhenova et al. Biochim Biophys Acta 1371:96–100, 1998b; Deryabina and Zvyagilskaya Biochemistry (Moscow) 65:1352–1356, 2000; Deryabina et al. J Biol Chem 276:47801–47806, 2001) were very resistant to Ca2+ overload. However, exposure of yeast mitochondria to 50–100 μM Ca2+ in the presence of the Ca2+ ionophore ETH129 induced collapse of the membrane potential, possibly due to activation of the fatty acid-dependent Ca2+/nH+-antiporter, with no classical mPTP induction. The absence of response in yeast mitochondria was not simply due to structural
limitations, since large-amplitude swelling occurred in the presence of alamethicin, a hydrophobic, helical peptide, forming
voltage-sensitive ion channels in lipid membranes. Ca2+- ETH129-induced activation of the Ca2+/H+-antiport system was inhibited and prevented by bovine serum albumin, and partially by inorganic phosphate and ATP. We subjected
yeast mitochondria to other conditions known to induce the permeability transition in animal mitochondria, i.e., Ca2+ overload (in the presence of ETH129) combined with palmitic acid (Mironova et al. J Bioenerg Biomembr 33:319–331, 2001; Sultan and Sokolove Arch Biochem Biophys 386:37–51, 2001), SH-reagents, carboxyatractyloside (an inhibitor of the ADP/ATP translocator), depletion of intramitochondrial adenine nucleotide
pools, deenergization of mitochondria, and shifting to acidic pH values in the presence of high phosphate concentrations.
None of the above-mentioned substances or conditions induced a mPTP-like pore. It is thus evident that the permeability transition
in yeast mitochondria is not coupled with Ca2+ uptake and is differently regulated compared to the mPTP of animal mitochondria. 相似文献
20.
Cira LA González GA Torres JC Pelayo C Gutiérrez M Ramírez J 《Antonie van Leeuwenhoek》2008,93(3):259-266
This paper describes the effect of the heterologous expression of tomatinase from Fusarium oxysporum f. sp lycopersici in Saccharomyces cerevisiae. The gene FoTom1 under the control of the S. cerevisiae phosphoglycerate kinase (PGK1) promoter was cloned into pYES2. S. cerevisiae strain Y45 was transformed with this vector and URA3 transformant strains were selected for resistance to α-tomatine. Two
transformants were randomly selected for further study (designated Y45-1 and Y45-2). Control strain Y45 was inhibited at 50 μM
α-tomatine, in contrast, transformants Y45-1 and Y45-2 did not show inhibition at 200 μM. Tomatinase activity was detected
by HPLC monitoring tomatine disappearance and tomatidine appearance in the supernatants of culture medium. Maximum tomatinase
activity was observed in the transformants after 6 h, remaining constant during the following 24 h. No tomatinase activity
was detected in the parental strain. Moreover, the transformants were able to grow and produce ethanol in a mix of Agave
tequilana Weber var. azul and Agave salmiana must, contrary to the Y45 strain which was unable to grow and ferment under these conditions. 相似文献