Search results for "biochemistry"
showing 10 items of 20172 documents
Medium-size droplets of methyl ricinoleate are reduced by cell-surface activity in the gamma-decalactone production by Yarrowia lipolytica.
2000
International audience; Size of methyl ricinoleate droplets during biotransformation into gamma-decalactone by Yarrowia lipolytica was measured in both homogenized and non-homogenized media. In non-homogenized but shaken medium, droplets had an average volume surface diameter d32 of 2.5 microm whereas it was 0.7 microm in homogenized and shaken medium. But as soon as yeast cells were inoculated, both diameters became similar at about 0.7 microm and did not vary significantly until the end of the culture. The growth of Y. lipolytica in both media was very similar except for the lag phase which was lowered in homogenized medium conditions.
Free Radicals Mediate Systemic Acquired Resistance
2014
Summary: Systemic acquired resistance (SAR) is a form of resistance that protects plants against a broad spectrum of secondary infections. However, exploiting SAR for the protection of agriculturally important plants warrants a thorough investigation of the mutual interrelationships among the various signals that mediate SAR. Here, we show that nitric oxide (NO) and reactive oxygen species (ROS) serve as inducers of SAR in a concentration-dependent manner. Thus, genetic mutations that either inhibit NO/ROS production or increase NO accumulation (e.g., a mutation in S-nitrosoglutathione reductase [GSNOR]) abrogate SAR. Different ROS function additively to generate the fatty-acid-derived azel…
Lipid composition of the vacuolar membrane of Acer pseudoplatanus cultured cells
1993
Tonoplast was prepared by osmotic lysis of a pure vacuolar fraction isolated from protoplasts derived from Acer pseudoplatanus cultured cells. After their extraction, neutral and polar lipids were separated by a thin layer chromatography. Phospholipids, glycolipids and neutral lipids represented 44.5%, 39.1% and 16.4% of total lipids, respectively. Sterols (glycosylated plus non-glycosylated forms) constituted 30.8% of total lipids; 75% of sterols were glycosylated. The most prominent lipids were phosphatidylethanolamine (20.8%), phosphatidylcholine (13.5%), ceramide monohexoside (12.8%), steryl glycoside (12.2%) and acylated steryl glycoside (10.9%). Glucose was the only sugar released by …
Relation of lenacil metabolism with growth inhibition of acer pseudoplatanus cell suspension
1983
Abstract The action of lenacil, a herbicide which inhibits photosynthesis, was studied on Acer pseudoplatanus cell suspensions. The compound was quickly and thoroughly metabolized by cells into two major chloroform-extractable metabolites, but cell growth was temporarily inhibited while some cells were killed. As cell suspensions were non-photosynthetic, the data suggest that lenacil has site(s) of action other than that of photosynthesis. However, as the effects on photosynthesis occur at much lower concentrations (Hilton et al., Weeds, 12 (1964) 129), the effects on cell growth may be considered as secondary.
Growth and activities of enzymes of primary metabolism in batch cultures of Catharanthus roseus cell suspension under different pCO2 conditions
1988
In vitro enzyme activities of glycolysis, pentose-phosphate pathway and dark CO2 fixation were assayed in batch cultures of heterotrophic Catharanthus roseus cells under various gassing rates and partial pressures of carbon dioxide. Detrimental effects of low pCO2 culture conditions on the growth characteristics could be linked to marked changes in levels of enzymes of primary metabolism during growth. The enzyme levels observed during the early stages of growth were found to be more stable when a constant pCO2 (20 mbar) was maintained and enabled exponential growth to be reached more rapidly. The importance of carbon dioxide as a “conditioning factor” of the culture medium is discussed.
Use of chlorophyll fluorescence induction kinetics to study translocation and detoxication of DCMU-type herbicides in plant leaves
1984
Transient levels of the fluorescence induction rise were used to quantify partial photosynthesis inhibition by DCMU -type herbicides in whole leaves. Assays in different crop or weed species showed a good accuracy in measurements (generally, variation was lower than 5%). This technique was applied to the problem of varietal selectivity of wheat towards chlortoluron.
Solute transporters in plant thylakoid membranes
2010
International audience; Plants utilize sunlight to drive photosynthetic energy conversion in the chloroplast thylakoid membrane. Here are located four major photosynthetic complexes, about which we have great knowledge in terms of structure and function. However, much less we know about auxiliary proteins, such as transporters, ensuring an optimum function and turnover of these complexes. The most prominent thylakoid transporter is the proton-translocating ATP-synthase. Recently, four additional transporters have been identified in the thylakoid membrane of Arabidopsis thaliana, namely one copper-transporting P-ATPase, one chloride channel, one phosphate transporter, and one ATP/ADP carrier…
Volatile components of ripe fruits of Morinda citrifolia and their effects on Drosophila
1996
Abstract The only larval resource of the specialist species, Drosophila sechellia , is ripe fruits of Morinda citrifolia . The chemical composition of this fruit, which is very toxic to most Drosophila species, was investigated and 51 compounds were abundant enough to be identified by GC-MS. The ripe fruit is characterized by a large amount of carboxylic acids, especially octanoic and hexanoic acids. The biological effects of the ripe fruit and its main acids were investigated with behavioural studies. Octanoic acid is responsible for the general toxicity of the fruit to most Drosophila species; D. sechellia is the only species which is resistant to this acid. Hexanoic acid has a unique eff…
Topical bioassay of Oberon® on Drosophila melanogaster pupae: delayed effects on ovarian proteins, cuticular hydrocarbons and sexual behaviour
2021
International audience; Spiromesifen (Oberon? 240 SC; concentrated solution; Bayer CropScience, Germany) a pesticide derived from spirocyclic tetronic acids, acts mainly though blocking lipid biosynthesis via acetyl-CoA carboxylase. However, its mode of action requires further analyses. This study aims to evaluate the sublethal effects of spiromesifen on the fruit fly Drosophila melanogaster. The treatment was carried out by topical application on newly moulted pupae using two concentrations (LD10 = 21.45 and LD25 = 39.53 ?g a.i./pupa). Our results showed that the developmental duration of larvae and pupae were not significantly affected by treatment. However, spiromesifen caused delayed ef…
Evolutionary Changes after Translational Challenges Imposed by Horizontal Gene Transfer
2019
International audience; Genes acquired by horizontal gene transfer (HGT) may provide the recipient organism with potentially new functions, but proper expression level and integration of the transferred genes in the novel environment are not granted. Notably, transferred genes can differ from the receiving genome in codon usage preferences, leading to impaired translation and reduced functionality. Here, we characterize the genomic and proteomic changes undergone during experimental evolution of Escherichia coli after HGT of three synonymous versions, presenting very different codon usage preference, of an antibiotic resistance gene. The experimental evolution was conducted with and without…