The pharmaceutical use of permethrin: sources and behavior during municipal sewage treatment.

Permethrin entered use in the 1970s as an insecticide in a wide range of applications, including agriculture, horticultural, and forestry, and has since been restricted. In the 21st century, the presence of permethrin in the aquatic environment has been attributed to its use as a human and veterinary pharmaceutical, in particular as a pedeculicide, in addition to other uses, such as a moth-proofing agent. However, as a consequence of its toxicity to fish, sources of permethrin and its fate and behavior during wastewater treatment are topics of concern. This study has established that high overall removal of permethrin (approximately 90%) was achieved during wastewater treatment and that this was strongly dependent on the extent of biological degradation in secondary treatment, with more limited subsequent removal in tertiary treatment processes. Sources of permethrin in the catchment matched well with measured values in crude sewage and indicated that domestic use accounted for more than half of the load to the treatment works. However, removal may not be consistent enough to achieve the environmental quality standards now being derived in many countries even where tertiary treatment processes are applied.

[GMOs in food: risk assessment, scientific management and regulatory aspects]. / Les OGM alimentaires: évaluation et gestion des risques; aspects scientifiques et réglementaires.

Genetic transformation constitutes a new tool for improvement of microorganisms, animals and plants used in food. We present foreseeable risks, as well as management measures to avoid unsuspected risks of GMOs. Few risks are specific to GMOs. Present elements of French and European regulations concerning placing on the market and follow up GMOs and other novel foods are described.

NR2D-containing NMDA receptors mediate tissue plasminogen activator-promoted neuronal excitotoxicity.

Although the molecular bases of its actions remain debated, tissue-type plasminogen activator (tPA) is a paradoxical brain protease, as it favours some learning/memory processes, but increases excitotoxic neuronal death. Here, we show that, in cultured cortical neurons, tPA selectively promotes NR2D-containing N-methyl-D-aspartate receptor (NMDAR)-dependent activation. We show that tPA-mediated signalling and neurotoxicity through the NMDAR are blocked by co-application of an NR2D antagonist (phenanthrene derivative (2S(*), 3R(*))-1-(phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid, PPDA) or knockdown of neuronal NR2D expression. In sharp contrast with cortical neurons, hippocampal neurons do not exhibit NR2D both in vitro and in vivo and are consequently resistant to tPA-promoted NMDAR-mediated neurotoxicity. Moreover, we have shown that activation of synaptic NMDAR prevents further tPA-dependent NMDAR-mediated neurotoxicity and sensitivity to PPDA. This study shows that the earlier described pro-neurotoxic effect of tPA is mediated by NR2D-containing NMDAR-dependent extracellular signal-regulated kinase activation, a deleterious effect prevented by synaptic pre-activation.

Dehydrin transcript fluctuations during a day/night cycle in drought-stressed sunflower.

To investigate environmental stimuli involved in the modulation of drought-induced gene expression, the influence of the day/night cycle on the expression of two dehydrin genes (HaDhn1 and HaDhn2) in leaves of sunflowers subjected to mild or severe drought stress has been studied. It was observed that the HaDhn1, but not HaDhn2, transcript oscillated in a diurnal fashion. In severely stressed plants, the peak of HaDhn1 mRNA accumulation occurred at midday.

Genetic analysis of mutants from Escherichia coli K12 unable to grow anaerobically without exogenous acceptor.

The ana mutation leads E. coli to need an exogenous electron acceptor for anaerobic growth. The affected gene maps near 26 min between chl C and tdk on the chromosome of the organism.

Formate hydrogenlyase system in Salmonella typhimurium LT2.

Isolation from Salmonella typhimurium of mutants unable to reduce benzyl viologen under anaerobic conditions has allowed the study of the factors involved in the multienzymic formate hydrogenylase system. 1. Depending on the affected activities, different classes of mutants were found: FHL-A mutants have lost formate dehydrogenase 1 and formate dehydrogenase 2 activities; mutations in fdhA (117 min) or fdhB (33 min) lead to such a phenotype. FHL-B and FHL-C mutants have lost formate dehydrogenase 2 activity and part or all of hydrogenase activity, respectively; both types correspond to mutations in the hyd gene (approximately 90 min). FHL-D mutants have lost only formate dehydrogenase 2 activity; fhlD gene maps at 120 min. 2. In some cases, mixtures of extracts from two mutants display formate dehydrogenase 2 and formate hydrogenylase activities. Restoration studies suggest the existence of one factor sensitive to growth conditions and inactivated by oxygen or heating. This factor which is present and active in FHL-C mutants, is probably the one missing in FHL-D mutants. 3. A new scheme for the formate hydrogenylase system is proposed, in which hydrogenase transfers electrons directly to benzyl viologen.

Genetic analysis of mutants of Escherichia coli K12 and Salmonella typhimurium LT2 deficient in hydrogenase activity.

A genetic study of mutants deficient in hydrogenase activity was performed. In E. coli, the affected gene (hyd) is located at 51 min, between cys C and nal B; in S. typhimurium, it probably lies in the homologous region of the chromosome.

A mutant of Escherichia coli deficient in pyruvate formate lyase.

A genetic study was performed on a mutation which has caused loss of pyruvate formate lyase. The gene affected is designated pfl and is located close to ser C, i.e. at 20 mn on the chromosomal map of E. coli.

sas1, an Arabidopsis mutant overaccumulating sodium in the shoot, shows deficiency in the control of the root radial transport of sodium.

A recessive mutation of Arabidopsis designated sas1 (for sodium overaccumulation in shoot) that was mapped to the bottom of chromosome III resulted in a two- to sevenfold overaccumulation of Na(+) in shoots compared with wild-type plants. sas1 is a pleiotropic mutation that also caused severe growth reduction. The impact of NaCl stress on growth was similar for sas1 and wild-type plants; however, with regard to survival, sas1 plants displayed increased sensitivity to NaCl and LiCl treatments compared with wild-type plants. sas1 mutants overaccumulated Na(+) and its toxic structural analog Li(+), but not K(+), Mg(2)+, or Ca(2)+. Sodium accumulated preferentially over K(+) in a similar manner for sas1 and wild-type plants. Sodium overaccumulation occurred in all of the aerial organs of intact sas1 plants but not in roots. Sodium-treated leaf fragments or calli displayed similar Na(+) accumulation levels for sas1 and wild-type tissues. This suggested that the sas1 mutation impaired Na(+) long-distance transport from roots to shoots. The transpiration stream was similar in sas1 and wild-type plants, whereas the Na(+) concentration in the xylem sap of sas1 plants was 5.5-fold higher than that of wild-type plants. These results suggest that the sas1 mutation disrupts control of the radial transport of Na(+) from the soil solution to the xylem vessels.

Chromosomal location of gene governing the trehalose utilization in Escherichia coli K12.

Several mutants unable to utilize trehalose were isolated from Escherichia coli, Their genetic analysis led to determine the following gene order on the chromosomal map: pur B-dad R-tre-hem a-trp. Furthermore, the tre gene belongs to the inversion of the trp chromosomal region between E. coli and S. typhimurium.

Molecular and physiological responses to water deficit in drought-tolerant and drought-sensitive lines of sunflower. Accumulation of dehydrin transcripts correlates with tolerance.

To investigate correlations between phenotypic adaptation to water limitation and drought-induced gene expression, we have studied a model system consisting of a drought-tolerant line (R1) and a drought-sensitive line (S1) of sunflowers (Helianthus annuus L.) subjected to progressive drought. R1 tolerance is characterized by the maintenance of shoot cellular turgor. Drought-induced genes (HaElip1, HaDhn1, and HaDhn2) were previously identified in the tolerant line. The accumulation of the corresponding transcripts was compared as a function of soil and leaf water status in R1 and S1 plants during progressive drought. In leaves of R1 plants the accumulation of HaDhn1 and HaDhn2 transcripts, but not HaElip1 transcripts, was correlated with the drought-adaptive response. Drought-induced abscisic acid (ABA) concentration was not associated with the varietal difference in drought tolerance. Stomata of both lines displayed similar sensitivity to ABA. ABA-induced accumulation of HaDhn2 transcripts was higher in the tolerant than in the sensitive genotype. HaDhn1 transcripts were similarly accumulated in the tolerant and in the sensitive plants in response to ABA, suggesting that additional factors involved in drought regulation of HaDhn1 expression might exist in tolerant plants.

Isolation and phenotypes of mutants from Salmonella typhimurium defective in formate hydrogenlyase activity.

A new method is described for the isolation of different mutants defective in formic dehydrogenase activity measured with benzyl viologen as electron acceptor.

Laboratoire de Chimie Bactérienne C.N.R.S., Marsielle, France.

Mutants of E. coli, completely devoid of nitrite reductase activity with glucose or formate as donor were studied. Biochemical analysis indicates that they are simultaneously affected in nitrate reductase, nitrite reductase, fumarate reductase and hydrogenase activities as well as in cytochrome C552 biosynthesis. The use of an antiserum specific for nitrate reductase shows that the nitrate reductase protein is probably missing. A single mutation is responsible for this phenotype: the gene affected, nir R, is located close to tyr R i.e. at 29 min on the chromosomal map.

Characterization of closely related delta-TIP genes encoding aquaporins which are differentially expressed in sunflower roots upon water deprivation through exposure to air.

We isolated five sunflower (Helianthus annuus) cDNAs belonging to the TIP (tonoplast intrinsic protein) family. SunRb7 and Sun gammaTIP (partial sequence) are homologous to tobacco TobRb7 and Arabidopsis gamma-TIP, respectively. SunTIP7, 18 and 20 (SunTIPs) are closely related and homologous to Arabidopsis delta-TIP (SunTIP7 and 20 have already been presented in Sarda et al., Plant J. 12 (1997) 1103-1111). As was previously shown for SunTIP7 and 20, expression of SunTIP18 and SunRb7 in Xenopus oocytes caused an increase in osmotic water permeability demonstrating that they are aquaporins. In roots, in situ hybridization revealed that SunTIP7 and 18 mRNAs accumulate in phloem tissues. The expression of TIP-like genes was studied in roots during 24 h water deprivation through exposure to air. During the course of the treatment, each SunTIP gene displayed an individual response: SunTIP7 transcript abundance increased, SunTIP18 decreased whereas that of SunTIP20 was transitorily enhanced. By contrast, SunRb7 and Sun gammaTIP mRNA levels did not fluctuate. Due to the changes in their transcript levels, it is proposed that SUNTIP aquaporins encoded by delta-TIP-like genes play a role in the sunflower response to drought.