Destruction of aflatoxins B1 and G1 in bread making

The effect of processing steps as well preservatives used in French bread making namely propionic acid and/or potassium sorbate (0.2%) on the destruction of aflatoxins B₁ and G₁ was studied. Mixing and baking processes showed marked destruction of aflatoxins B₁ and G₁; being 71.2% and 52.5% for aflatoxin B₁ after mixing and baking steps, while reaching 73.9% and 54.5% for aflatoxin G₁. Fermentation step caused additional 15.3% and 15.0% destruction of aflatoxins B₁ and G₁. On the other hand, aflatoxin B₁ destruction was 79.2% and 50.7% when propionic acid was used and 75.3 and 56.7% in the presence of potassium sorbate and after mixing and baking steps respectively. Concerning aflatoxins G₁ it was found that mixing and baking steps showed destruction of 81.9% and 53.4% in the presence of propionic acid and 75.1 and 49.4% in the presence of potassium sorbate in this respective order. Generally, it can be concluded that using propionic acid as preservative appeared to be more effective on the destruction of aflatoxins B₁ and G₁ than potassium sorbate in French bread making.     

Effects of Carnosine and Anserine on the Destruction of Vitamin B12 with Vitamin C in the Presence of Copper

Vitamin B₁₂ is destroyed by the addition of substantial amounts of vitamin C in the presence of copper. Effects of carnosine and anserine, natural water-soluble antioxidants, on the destruction of vitamin B₁₂, were studied. Addition of carnosine (l0mM) effectively repressed the destruction of vitamin B₁₂, but anserine had only weak inhibitory effects.     

Processes of methane cycle and destruction of organic matter during the ice period in freshwater bodies of various types

Studies conducted in January to March at different parts of the Rybinsk Reservoir, in lakes of various types, and in a pond have demonstrated that the processes of СН₄ cycle during the ice period play an important role in the destruction of С_org and functioning of the ecosystem food webs. In highly trophic polluted lakes, the formation of СН₄ takes place both in silts and in the water column, and its gross production reaches a high summer level of 540–1220 mg С_org/(m² day). Taking into the account methanogenesis, 68–97% of the destruction of organic matter (OM) occurs due to the processes in bottom sediments. In the silts of productive lakes, only anaerobic processes cause the destruction.     

Mechanism of in vivo carbon tetrachloride-induced liver microsomal cytochrome P-450 destruction.

Prior administration of aminotriazole (3-amino-1,2,4-triazole) or pyrazole to rats resulted in a significant prevention of the CCl₄-induced decrease in the liver microsomal P-450 content. In A/J mice the CCl₄ activation and P-450 destruction occurred in absolute absence of lipid peroxidation as determined by uv absorption. The data suggest that P-450 destruction is mainly mediated by direct attack of CCl₄ metabolites rather than by CCl₄-induced lipid peroxidation.     

Optical characteristics of the plasma of a transverse volume discharge in a Ne/Ar/SiH4 mixture

Results are presented from studies of the characteristics of a transverse volume discharge in a Ne/Ar/SiH₄ mixture at pressures of 5–35 kPa. It is shown that SiI 288.2-nm, H_β 486.1-nm, and NeI 585.3-nm lines and H₂. Lyman bands can be used to monitor the process of destruction of silane molecules. The obtained porous film, consisting of the products of SiH₄ destruction, is of interest for yielding siliceous fullerenes and for application in optoelectronics.     

Effects of Hydroxylamine on Photosystem II: I. Factors Affecting the Decay of O(2) Evolution

Illumination of chloroplasts in the presence of NH₂OH (2 mm) leads to the destruction of all system II activities without affecting system I activity. The system II primary charge separation remains intact when incubated with this agent in the dark with release of one of the system II Mn pools and simultaneous destruction of O₂ evolving capacity. The size of the Mn pool associated with the O₂ evolving center is calculated to be 4 Mn/O₂-evolving center.     

Male production by aphids prenatally treated with precocene: Prevention by short-term kinoprene treatment

We previously reported that precocene caused the aphid Myzus persicae to produce male offspring, and further, that daughters (G₁) of precocene-treated females also produced males in several temporal patterns. These patterns characteristically exhibited male production early in the reproductive sequence and/or approximately 10 days later. We suggested that ovulation of male eggs might occur at subthreshold juvenile hormone concentrations immediately after precocene treatment (i.e., during the late embryonic stages of the G₁ aphids) and again in the last larval instar of the G₁ aphids. This paper describes experiments in which G₁ aphids were exposed to the JH analog kinoprene prenatally and in the last instar. It was shown that these treatments delayed, eliminated, or interrupted the expected sequences of males, thus providing evidence for the proposed scheme of male determination. The condition of the corpus allatum in G₁ adults correlated with the pattern of male production; in continuous male producers the corpus allatum had undergone delayed destruction. A schematic model of the endocrine control of male determination is presented.     

Absence of pfr destruction in the modulation of phenylalanine ammonia-lyase synthesis of mustard cotyledons

The relationship between the amount of active phytochrome (Pfr) produced by 5-minute light pulses and the rate of subsequent enzyme accumulation (phenylalanine ammonia-lyase, EC 4.3.1.5) of mustard (Sinapis alba L.) cotyledons was investigated. The response rapidly adjusts to changes of the Pfr level produced by light pulses of different wavelengths. Regardless of total phytochrome levels in the cotyledons, response adjustments to new photostationary states (_λ) are correlated with _α values. On the other hand, the kinetics of enzyme accumulation shows no influence of Pfr destruction as determined spectrophotometrically (τ_½ = 45 min) in the same organ (see Schäfer et al. 1973 Photochem Photobiol 18: 331-334). It is concluded that the phytochrome molecules involved in the regulation of this response by light pulses comprise a small fraction of the total phytochrome of the cotyledons. In contrast to bulk phytochrome this fraction appears to be not subject to Pfr destruction.     

Changes in the Spatial Structure of the Destruction Process under the Conditions of Atmospheric Pollution of Forest Ecosystems

Contamination of the southern taiga forests (Middle Urals) by from cooper smelters (heavy metals combined with SO₂) not only decreases the mean rate of decomposition of pure cellulose, but also radically changes the spatial structure of the destruction process. Heterogeneity of distribution of the destruction rate is sharply increased near the source of emission due to differentiation of the space into microsites with high and low destruction rates. The range of spatial heterogeneity amounts to several tens of centimeters and the distribution of microsites with a high rate is random within several tens of meters. A hypothesis has been put forward that the described changes in the spatial structure of the destruction process are related, above all, to disturbed colonization of the substrate by soil microfungi.     

The effects of carbon disulphide on rat liver microsomal mixed-function oxidases, in vivo and in vitro

An intraperitoneal dose of CS₂ (500mg/kg) to male rats resulted in loss of liver microsomal mixed-function-oxidase activity (85% loss of biphenyl 4-hydroxylase), followed by denaturation of liver cytochrome P-450 to cytochrome P-420, and degradative loss of both cytochromes (50% loss). Losses of NADPH–cytochrome c reductase (20%) and cytochrome b₅ were considerably less. Intraperitoneal administration of CS₂ (100mg/kg) to rats pretreated wtih phenobarbitone or 3-methylcholanthrene resulted in similar losses, but the rate of destruction was greater with cytochrome P-450 than with cytochrome P-448. At 12h after intraperitoneal injection of CS₂ to non-pretreated rats, a new cytochrome (P-448) appeared. Rat liver microsomal preparations incubated with CS₂ in the presence of NADPH and O₂ resulted in loss of cytochrome P-450 and mixed-function-oxidase activity directly related to the concentration of CS₂ (10–100μm) and to the period of incubation. Addition of EDTA (1mm) completely inhibited this destruction of cytochrome P-450 by CS₂ in vitro. Addition of CS₂ to liver microsomal preparations resulted in moderate increases in the K_s values for type-I or type-II substrates, but these were insufficient to account for the inhibition of the mixed-function oxidases. We therefore suggest that desulphuration of CS₂ leads to binding of the S to cytochrome P-450, denaturation of cytochrome P-450 to cytochrome P-420, and ultimately to destruction of these cytochromes by autoxidation.     

Phytochrome in cultured wild carrot tissue. I. Synthesis

Stable levels of P_FR occur in light-grown suspension cultures of wild carrot. Upon darkening such tissue, P_R accumulates until the high P_R level characteristics of dark-grown tissue is reached. Data are compatible with the idea of an equilibrium between processes of synthesis and destruction in tissue grown in the light. Reappearance of phytochrome also follows light-induced pigment destruction in dark-grown tissue. The rate of P_R appearance is similar in both cases. The rate of disappearance of P_FR, however, is slower in light-grown tissue than in dark-grown tissue.     

Chlorophyll destruction by the bisulfite-oxygen system

Destruction of chlorophyll, as determined by the loss in absorbance at 665 nm, occurred in two in vitro systems in the presence of bisulfite in 76% ethanol. The first system required light and O₂ in addition to bisulfite and exhibited an optimum pH of 4. Chlorophyll functioned as a photosensitizer and there was little chlorophyll destruction occurring above pH 5. With 286 μeinsteins m⁻² irradiation, approximately 80% of the chlorophyll was destroyed in three minutes. In the second system, chlorophyll destruction in the presence of bisulfite occurred in the dark and required Mn²⁺, O₂, and glycine. Destruction of chlorophyll in this system was much more rapid than in the light system with approximately 70% destruction occurring in two seconds. In both systems, chlorophyll destruction was linked to bisulfite oxidation. The free radical scavengers hydroquinone, butylated hydroxytoluene, 1,2-dihydroxybenzene-3,5-disulfonic acid, and α-tocopherol were effective in inhibiting the destruction of chlorophyll in both systems. The singlet O₂ scavengers, 2,5-dimethylfuran and 1,3-diphenylisobenzofuran, were ineffective inhibitors and β-carotene only slightly effective when tested in the light system. The evidence suggests that in these two systems chlorophyll was destroyed by free radicals, probably superoxide radical, which was produced during the aerobic oxidation of bisulfite.     

Chitosan-induced programmed cell death in plants

Chitosan, CN⁻, or H₂O₂ caused the death of epidermal cells (EC) in the epidermis of pea leaves that was detected by monitoring the destruction of cell nuclei; chitosan induced chromatin condensation and marginalization followed by the destruction of EC nuclei and subsequent internucleosomal DNA fragmentation. Chitosan did not affect stoma guard cells (GC). Anaerobic conditions prevented the chitosan-induced destruction of EC nuclei. The antioxidants nitroblue tetrazolium or mannitol suppressed the effects of chitosan, H₂O₂, or chitosan + H₂O₂ on EC. H₂O₂ formation in EC and GC mitochondria that was determined from 2′,7′-dichlorofluorescein fluorescence was inhibited by CN⁻ and the protonophoric uncoupler carbonyl cyanide m-chlorophenylhydrazone but was stimulated by these agents in GC chloroplasts. The alternative oxidase inhibitors propyl gallate and salicylhydroxamate prevented chitosan- but not CN⁻-induced destruction of EC nuclei; the plasma membrane NADPH oxidase inhibitors diphenylene iodonium and quinacrine abolished chitosan- but not CN⁻-induced destruction of EC nuclei. The mitochondrial protein synthesis inhibitor lincomycin removed the destructive effect of chitosan or H₂O₂ on EC nuclei. The effect of cycloheximide, an inhibitor of protein synthesis in the cytoplasm, was insignificant; however, it was enhanced if cycloheximide was added in combination with lincomycin. The autophagy inhibitor 3-methyladenine removed the chitosan effect but exerted no influence on the effect of H₂O₂ as an inducer of EC death. The internucleosome DNA fragmentation in conjunction with the data on the 3-methyladenine effect provides evidence that chitosan induces programmed cell death that follows a combined scenario including apoptosis and autophagy. Based on the results of an inhibitor assay, chitosan-induced EC death involves reactive oxygen species generated by the NADPH oxidase of the plasma membrane.     

A new visualization scheme of chemical energy density and bonds in molecules

Covalent bond describes electron pairing in between a pair of atoms and molecules. The space is partitioned in mutually disjoint regions by using a new concept of the electronic drop region R_D, atmosphere region R_A, and the interface S (Tachibana in J Chem Phys 115:3497–3518, 2001). The covalent bond formation is then characterized by a new concept of the spindle structure. The spindle structure is a geometrical object of a region where principal electronic stress is positive along a line of principal axis of the electronic stress that connects a pair of the R_Ds of atoms and molecules. A new energy density partitioning scheme is obtained using the Rigged quantum electrodynamics (QED). The spindle structure of the stress tensor of chemical bond has been disclosed in the course of the covalent bond formation. The chemical energy density visualization scheme is applied to demonstrate the spindle structures of chemical bonds in H₂, C₂H₆, C₂H₄ and C₂H₂ systems.Figure Field theory of the energy density.     

Destruction and possible de novo synthesis of phytochrome in subcellular fractions of laminae from Avena sativa L.

Phytochrome was determined in etiolated laminae of Avena sativaL. either without pretreatment or after 5 min of red irradiation followed by different periods of darkness (0–24 h). At given intervals laminae were homogenized and phytochrome was determined spectrophotometrically in the total homogenate and in purified etioplasts and mitochondria. Enhanced specific activity of phytochrome was found in all fractions after the irradiation in comparison to dark controls. Phytochrome destruction was observed in all fractions at the beginning of the subsequent dark period. Whereas the homogenate and the mitochondrial fraction showed a continuous destruction so that phytochrome reached a level far below that in etiolated plants, the phytochrome level in the plastid fraction reacheda minimum at 2 h with a subsequent increase beyond the dark level. This increase was most pronounced between 4 and 8 h after the red irradiation. The results are discussed in terms of the destruction and possible de novo synthesis of phytochrome that may be different in mitochondria and plastids.Abbreviations P_tot total phytochrome - P_r red absorbing form of phytochrome - P_fr far-red absorbing form of phytochrome - ER endoplasmic reticulum     

The self-destructive personality of a cell cycle in transition

The transition from G₁ to S phase, sister chromatid separation in anaphase, and the exit from mitosis are driven by the destruction of cell cycle regulatory proteins by distinct ubiquitin-dependent proteolytic pathways. The components and targets of these key degradation pathways are now becoming clear. Genetic and biochemical dissections of these extremely specific and well regulated destruction pathways are providing fundamental insights into the mechanisms of control of the cell division cycle.     

Interaction of Pseudomonas cytochrome cd1 with the cytoplasmic membrane

Labelling with ferritin-conjugated antibody shows that Pseudomonas cytochrome cd₁ is associated with the inner surface of the cytoplasmic membrane. Cytochrome cd₁ is, however, enriched to the soluble fraction obtained after destruction of Pseudomonas spheroplasts. Comparison of the respiratory nitrite reductase activities, due to this cytochrome, between different cellular fractions and the purified enzyme shows that while the kinetic pattern and the temperature dependence of the activity remain almost the same the molecular activity is enhanced when the enzyme is released from cells.A new assay of respiratory nitrite reductase was developed in this study. The method is based on determination of the stoichiometrical proton consumption accompanying nitrite reduction.     

Stability of phytochrome concentration in dicotyledonous tissues under continuous far-red light

Summary The phytochrome concentration in dark-grown seedlings of Pisum sativum, Phaseolus aureus and Sinapis alba remained constant under continuous far-red illumination for periods of up to 6 hours. Similar treatment of Zea mays seedlings reduced the phytochrome concentration by more than 60 percent. The results in the dicotyledonous seedlings may be due to the reversion of P_fr to P_r at a rate sufficient to prevent P_fr destruction; no evidence for reversion has been detected in Zea. Typical photomorphogenic responses were observed in the dicotyledonous seedlings in the absence of P_fr destruction.Research carried out at Brookhaven National Laboratory under the auspices of the U.S. Atomic Energy Commission.     

Fate of aflatoxins B1 and G1 residues during biscuit processing

Effect of biscuit processing on the destruction of aflatoxins B₁ and G₁ with and/or without some commonly leavening agents used namely sodium bicarbonate, ammonium bicarbonate and sodium bisulfite and sodium chloride. It was found that mixing step reduced the concentration of aflatoxins B₁ and G₁ by 80.7% and 82.7%, while the effect of baking step being 28.9% and 21.5%. The effect of mixing was found to be more pronounced than that baking step. The highest destruction effect on aflatoxin B1 was observed by adding a mixture composed of sodium and ammonium bicarbonate and sodium bisulfite followed by sodium chloride, sodium bisulfite, ammonium bicarbonate and/or sodium bicarbonate alone, where the reduction values of toxin after mixing were 93.4,91.9,91.7, 88.8 and 86.6% respectively, while the baking effect ranged 17.2 to 34.5% in the presence of different leaving agents added. Concerning aflatoxin G1; the highest destructive effect of toxin was adsorbed by adding a mixture of sodium and ammonium bicarbonate and sodium bisulfite followed by sodium bisulfite, sodium chloride, ammonium bicarbonate and/or sodium bicarbonate alone since the destruction values of such toxin after mixing were 96.2%, 92.8%, 92.6%, 89.0% and 87.7% respectively, while the baking effect ranged 20.9 to 34.5% in all leavening agents added.