Glucocorticoids can induce PTSD-like memory impairments in mice

Posttraumatic stress disorder (PTSD) is characterized by a hypermnesia of the trauma and by a memory impairment that decreases the ability to restrict fear to the appropriate context. Infusion of glucocorticoids in the hippocampus after fear conditioning induces PTSD-like memory impairments and an altered pattern of neural activation in the hippocampal-amygdalar circuit. Mice become unable to identify the context as the correct predictor of the threat and show fear responses to a discrete cue not predicting the threat in normal conditions. These data demonstrate PTSD-like memory impairments in rodents and identify a potential pathophysiological mechanism of this condition.     

Impact of the genetic diversity of three cyst nematodes on the effectiveness of root exudates to induce hatching

European Journal of Plant Pathology - Cyst nematodes are sedentary endoparasites of plants which cause important economic losses worldwide. New nematode control measures are needed since the...     

Effect of Mixing Conditions on the Behavior of Lipoxygenase,Peroxidase, and Catalase in Wheat Flour Doughs

The effect of mixing has been tested on the extractable activities of lipoxygenase, peroxidase, and catalase from dough after 2, 5, and 20 min of mixing, and 30 min of rest period after 20 min of mixing. Different mixing conditions have been studied including temperature, atmosphere, speed, amount of water added to the dough, buffer solutions between pH 3.6 and 7.5 added to the dough, and different additives (linoleic acid, guaiacol, hydrogen peroxide, ascorbic acid, cysteine, yeast, and sodium chloride). In all the mixing conditions tested, the dough peroxidase activity remains equivalent to the initial flour activity, whereas losses in lipoxygenase and catalase activities largely varied according to mixing conditions. The results show that a self-destruction mechanism as well as physicochemical denaturation are responsible for these losses. Lipoxygenase losses seem mainly associated with the former mechanism, whereas catalase losses are highly increased in acidic conditions (physicochemical denaturation). Therefore, the relative impact of the three oxidoreducing enzymes may be largely modulated by mixing conditions.     

Technology observed: attitudes of a wary public

Our analysis of the interviews with a sample of the California public about a range of their attitudes toward technology shows that a modification of our understanding of the collective state of mind on this subject is in order. The current assessment of the public as largely, and somewhat vacantly, enamored with science and technology does not hold. Nor does a picture of a public generally hostile and alienated by technology. Neither panglossian optimism nor prophecies of doom can be supported by these interviews. Rather a more mixed picture emerges. Out of that picture, a potential public can be isolated, whose mood it behooves science policy-makers to watch. This group tends to associate a number of related conditions with technological development; moreover, it is likely to make assessments on those relationships so perceived. To the degree this group has "antitechnological" feelings, these feelings are clearly linked to the group's awareness that the social consequences of technology can produce conditions which threaten important values. The particular distribution of age and political identification suggests that those who are young and who identify themselves as "liberal" form the core of potential opposition to technological development and that such opposition is at least in part a function of different value preferences. The associations between political identification and attitudes about technology, distrust of decision-making, and concern for environmental impacts all make this point. In short, "technological dissent" cannot be written off as antiintellectual and without foundation. It is, in fact, preeminently sensible. What the alignments visible within the potential public portend for the future is not clear, although they do not allow us to accept an inference drawn from past studies-that because the young retain confidence in scientists and engineers all is well for the general climate of science and technology. We can only speculate whether, as these younger people grow older, they will carry their uneasiness about technology with them. Were they to do so, and were this group to be joined by still younger people who also hold these wary attitudes, the context of scientific and technological work could become much more fraught with political controversy. Another point emerging from our interpretation is how very crucial to continued free scientific inquiry is the distinction between scientific work and technological activities apparently now made by a sizable portion of the public. Should this distinction become lost, perhaps through continual merging of science's role with technology's by the popular press, attitudes now mainly associated with technology could spill over to scientific research as well. Yet our data also provide evidence of the successes of the scientific and technological communities. They have become such a critical part of life that people are seriously concerned with their future development. The opportunity is present for both communities to find ways of responding to the situation so that thoughtful action can be taken to implement technology for the benefit of the commonweal.     

Solid–liquid extraction of protopine from Fumaria officinalis L.—Kinetic modelling of influential parameters

The influences of such parameters as percentage of ethanol in solvent, solid–liquid weight ratio and pH of medium on the protopine extraction from Fumaria officinalis particles with mean radius of 0.4–0.5 mm was studied. A mathematical model, describing the importance of each parameter on the extraction of protopine with pseudo-second-order kinetics was proposed and the results were discussed. A numerical solution was obtained, which was compared with the experimental data for the increase in protopine concentration in the liquid phase. A satisfactory fit with experimental data was observed.     

The intramacrophagic environment of Brucella suis and bacterial response

Phagocytes have developed various antimicrobial defense mechanisms to eliminate pathogens. They comprise the oxidative burst, acidification of phagosomes, or fusion of phagosomes with lysosomes. Facultative intracellular bacteria, in return, have developed strategies counteracting the host cell defense, resulting in intramacrophagic survival. Until lately, only very little was known about the phagosomal compartment containing Brucella spp., the environmental conditions the bacteria encounter, and the pathogen's stress response. Recently, we have determined that the phagosomes acidify rapidly to a pH of 4.0-4.5 following infection, but this early acidification is crucial for intracellular replication as neutralization results in bacterial elimination. A vacuolar proton-ATPase is responsible for this phenomenon that is not linked to phagosome-lysosome fusion. On the contrary, in vitro reconstitution assays revealed association only between phagosomes containing killed B. suis and lysosomes, describing the absence of phagolysosome fusion due to specific recognition inhibition for live bacteria. Further evidence for the necessity of an intact, acidic phagosome as a predominant niche of brucellae in macrophages was obtained with a strain of B. suis secreting listeriolysin. It partially disrupts the phagosomal membranes and fails to multiply intracellularly. How does B. suis adapt to this environment? We have identified and studied a series of genes that are involved in this process of adaptation. The bacterial heat shock protein and chaperone DnaK is induced in phagocytes and it is essential for intracellular multiplication. A low-level, constitutive expression of dnaK following promoter exchange does not restore intramacrophagic survival. Another chaperone and heat shock protein, ClpB, belonging to the family of ClpATPases, is important for the resistance of B. suis to several in vitro stresses, but does not contribute to intramacrophagic survival of the pathogen. Additional bacterial genes specifically induced within the phagocyte were identified by an intramacrophagic screen of random promoter fusions to the reporter gene gfp. A large majority of these genes are encoding proteins involved in transport of nutrients (sugars, amino acids), or cofactors, such as nickel. Analysis of the intracellular gene activation reveals that low oxygen tension is encountered by B. suis. Altogether, these results suggest three major stress conditions encountered by brucellae in the phagosome: acid stress, starvation and low oxygen tension.     

Inhibition of insulin release by norepinephrine in man

Normal subjects were given glucose (300 mg/ min) or tolbutamide (1 g, intravenously), alone and during intravenous infusions of norepi-nephrine (6 lg/ min). Immunoreactive insulin concentration was less than expected during the infusions of norepinephrine, but returned to higher values after the norepinephrine infusions. From these data it is concluded that norepinephrine inhibits the release of insulin from pancreatic beta cells.     

Spatial variability of the functional stability of microbial respiration process: a microcosm study using tropical forest soil

Purpose

Understanding the ability of ecosystem processes to resist to and to recover from disturbances is critical to sustainable land use. However, the spatial variability of the stability has rarely been addressed. Here, we investigated the functional stability of a soil microbial process for 24 soils collected from adjacent locations from a 0.3?ha tropical rainforest plot in Paracou, French Guiana.

Materials and methods

The 24 locations were characterized regarding soil chemical and biological (microbial diversity) parameters and forest structure. The corresponding soils were submitted to an experimental transient heat disturbance during a microcosm experiment. The response of the respiration process was followed using substrate-induced respiration (SIR).

Results and discussion

The response of soil SIR to heat disturbance varied widely between samples. The variability of the SIR response increased just after the disturbance, and a global rather homogeneous decrease in SIR rates was observed 15 and 30?days after. The stability of SIR in response to heat disturbance could not be related to either the genetic or the metabolic diversity of the microbial community. The initial level of SIR before the disturbance was the soil variable that best correlated with the impact of the disturbance: the soil locations with the highest initial SIR rates were the most affected 15 and 30?days after the heat disturbance.

Conclusions

Such a heterogeneous response suggests that the response of soil processes to a disturbance will be difficult to assess from only local-scale analyses and highlights the need for spatial explicitness in understanding biogeochemical processes.     

The intramacrophagic environment of Brucella suis and bacterial response

Phagocytes have developed various antimicrobial defense mechanisms to eliminate pathogens. They comprise the oxidative burst, acidification of phagosomes, or fusion of phagosomes with lysosomes. Facultative intracellular bacteria, in return, have developed strategies counteracting the host cell defense, resulting in intramacrophagic survival.Until lately, only very little was known about the phagosomal compartment containing Brucella spp., the environmental conditions the bacteria encounter, and the pathogen’s stress response. Recently, we have determined that the phagosomes acidify rapidly to a pH of 4.0–4.5 following infection, but this early acidification is crucial for intracellular replication as neutralization results in bacterial elimination. A vacuolar proton-ATPase is responsible for this phenomenon that is not linked to phagosome–lysosome fusion. On the contrary, in vitro reconstitution assays revealed association only between phagosomes containing killed B. suis and lysosomes, describing the absence of phagolysosome fusion due to specific recognition inhibition for live bacteria. Further evidence for the necessity of an intact, acidic phagosome as a predominant niche of brucellae in macrophages was obtained with a strain of B. suis secreting listeriolysin. It partially disrupts the phagosomal membranes and fails to multiply intracellularly.How does B. suis adapt to this environment? We have identified and studied a series of genes that are involved in this process of adaptation. The bacterial heat shock protein and chaperone DnaK is induced in phagocytes and it is essential for intracellular multiplication. A low-level, constitutive expression of dnaK following promoter exchange does not restore intramacrophagic survival. Another chaperone and heat shock protein, ClpB, belonging to the family of ClpATPases, is important for the resistance of B. suis to several in vitro stresses, but does not contribute to intramacrophagic survival of the pathogen. Additional bacterial genes specifically induced within the phagocyte were identified by an intramacrophagic screen of random promoter fusions to the reporter gene gfp. A large majority of these genes are encoding proteins involved in transport of nutrients (sugars, amino acids), or cofactors, such as nickel. Analysis of the intracellular gene activation reveals that low oxygen tension is encountered by B. suis.Altogether, these results suggest three major stress conditions encountered by brucellae in the phagosome: acid stress, starvation and low oxygen tension.