Lipase-catalyzed chemoselective aminolysis of various aminoalcohols with fatty acids

Candida antarctica lipase is well known to convert amines and alcohols into amides and esters. This report describes the development of a solvent-free enzymatic process for the production of fatty alkanolamides. The aminolysis of linoleyl ethyl ester with several aminoalcohols from C2 to C6 (linear or branched compounds), and the very high selectivity of amide compounds have been observed.Our investigation leads us to develop an original biotechnological process for the chemoselective synthesis of new active molecules for cutaneous application.     

Fatty acids, unusual glycophospholipids and DNA analyses of thermophilic bacteria isolated from hot springs

The composition of fatty acids in 12 strains of the genera Thermus, Meiothermus, Geobacillus and Alicyclobacillus was analyzed by gas chromatography–mass spectrometry. Major FAs found in the profiles included i-15:0, i-17:0, ai-15:0, i-16:0, 16:0, ai-17:0, together with some minor components. Branched FAs were predominant, forming more than 80% of all FAs measured. Fast atom bombardment-mass spectrometry was used for analysis of unusual glycophospholipids, i.e., acylglycosylcardiolipins from genera Geobacillus and Alicyclobacillus and 1-(hydroxy(2-(O-acylglycosyl-oxy)hexadecyloxy)phosphoryloxy) hexadecan-2-yl esters of C15–C17 acids from genera Thermus and Meiothermus. Cloning and preliminary sequence analysis of 16S rDNA showed that these isolates belong to the genera Thermus, Meiothermus, Geobacillus and Alicyclobacillus.     

Localization of the Brainstem GABAergic Neurons Controlling Paradoxical (REM) Sleep

Paradoxical sleep (PS) is a state characterized by cortical activation, rapid eye movements and muscle atonia. Fifty years after its discovery, the neuronal network responsible for the genesis of PS has been only partially identified. We recently proposed that GABAergic neurons would have a pivotal role in that network. To localize these GABAergic neurons, we combined immunohistochemical detection of Fos with non-radioactive in situ hybridization of GAD67 mRNA (GABA synthesis enzyme) in control rats, rats deprived of PS for 72 h and rats allowed to recover after such deprivation. Here we show that GABAergic neurons gating PS (PS-off neurons) are principally located in the ventrolateral periaqueductal gray (vlPAG) and the dorsal part of the deep mesencephalic reticular nucleus immediately ventral to it (dDpMe). Furthermore, iontophoretic application of muscimol for 20 min in this area in head-restrained rats induced a strong and significant increase in PS quantities compared to saline. In addition, we found a large number of GABAergic PS-on neurons in the vlPAG/dDPMe region and the medullary reticular nuclei known to generate muscle atonia during PS. Finally, we showed that PS-on neurons triggering PS localized in the SLD are not GABAergic. Altogether, our results indicate that multiple populations of PS-on GABAergic neurons are distributed in the brainstem while only one population of PS-off GABAergic neurons localized in the vlPAG/dDpMe region exist. From these results, we propose a revised model for PS control in which GABAergic PS-on and PS-off neurons localized in the vlPAG/dDPMe region play leading roles.     

Hepatitis C virus entry depends on clathrin-mediated endocytosis

Due to difficulties in cell culture propagation, the mechanisms of hepatitis C virus (HCV) entry are poorly understood. Here, postbinding cellular mechanisms of HCV entry were studied using both retroviral particles pseudotyped with HCV envelope glycoproteins (HCVpp) and the HCV clone JFH-1 propagated in cell culture (HCVcc). HCVpp entry was measured by quantitative real-time PCR after 3 h of contact with target cells, and HCVcc infection was quantified by immunoblot analysis and immunofluorescence detection of HCV proteins expressed in infected cells. The functional role of clathrin-mediated endocytosis in HCV entry was assessed by small interfering RNA-mediated clathrin heavy chain depletion and with chlorpromazine, an inhibitor of clathrin-coated pit formation at the plasma membrane. In both conditions, HCVpp entry and HCVcc infection were inhibited. HCVcc infection was also inhibited by pretreating target cells with bafilomycin A1 or chloroquine, two drugs known to interfere with endosome acidification. These data indicate that HCV enters target cells by clathrin-mediated endocytosis, followed by a fusion step from within an acidic endosomal compartment.     

Leishmania major Glycosylation Mutants Require Phosphoglycans (lpg2 ?) but Not Lipophosphoglycan (lpg1 ?) for Survival in Permissive Sand Fly Vectors

Background

Sand fly species able to support the survival of the protozoan parasite Leishmania have been classified as permissive or specific, based upon their ability to support a wide or limited range of strains and/or species. Studies of a limited number of fly/parasite species combinations have implicated parasite surface molecules in this process and here we provide further evidence in support of this proposal. We investigated the role of lipophosphoglycan (LPG) and other phosphoglycans (PGs) in sand fly survival, using Leishmania major mutants deficient in LPG (lpg1 ⁻), and the phosphoglycan (PG)-deficient mutant lpg2 ⁻. The sand fly species used were the permissive species Phlebotomus perniciosus and P. argentipes, and the specific vector P. duboscqi, a species resistant to L. infantum development.

Principal Findings

The lpg2 ⁻ mutants did not survive well in any of the three sand fly species, suggesting that phosphoglycans and/or other LPG2-dependent molecules are required for parasite development. In vitro, all three L. major lines were equally resistant to proteolytic activity of bovine trypsin, suggesting that sand fly-specific hydrolytic proteases or other factors are the reason for the early lpg2 ⁻ parasite killing. The lpg1 ⁻ mutants developed late-stage infections in two permissive species, P. perniciosus and P. argentipes, where their infection rates and intensities of infections were comparable to the wild type (WT) parasites. In contrast, in P. duboscqi the lpg1 ⁻ mutants developed significantly worse than the WT parasites.

Conclusions

In combination with previous studies, the data establish clearly that LPG is not required for Leishmania survival in permissive species P. perniciosus and P. argentipes but plays an important role in the specific vector P. duboscqi. With regard to PGs other than LPG, the data prove the importance of LPG2-related molecules for survival of L. major in the three sand fly species tested.     

Intravenous rutin in rat exacerbates isoprenaline-induced cardiotoxicity likely due to intracellular oxidative stress

Objectives: Rutin, quercetin-3-O-rutinoside, a natural flavonol glycoside, has shown various in vitro benefits with potential use treating human diseases, especially cardiovascular system disorders. Antioxidant properties are assumed to underlie the majority of these benefits. Yet rutin pro-oxidant properties have been reported as well. Our research group has recently shown aggravating effects on isoprenaline (ISO)-induced cardiotoxicity in Wistar:Han rats after 24?hours.

Methods: This study was designed to examine in more detail the reasons for the negative effects of rutin (11.5 and 46?mg/kg, i.v.) after administration of ISO (100?mg/kg, s.c.) in rats within 2?hours of continuous experiment and in the H9c2 cardiomyoblast-derived cell line.

Results: Like our previous findings, rutin did not (11.5 or 46?mg/kg, i.v.) reduce the ISO-induced mortality within 2?hours although the lower dose significantly reduced cardiac troponin T (cTnT) and partly improved the histological findings. In contrast, the higher dose increased the mortality in comparison with solvent (1.26% w/v sodium bicarbonate). This was not caused by any specific haemodynamic disturbances. It appears to be associated with oxidative stress as rutin enhanced intracellular reactive oxygen species formation in vitro and had the tendency to increase it in vivo.

Conclusions: Rutin, likely due to its pro-oxidative effects, can exacerbate catecholamine cardiotoxicity depending on the dose used.     

Behavioural synchronization of large‐scale animal movements – disperse alone,but migrate together?

Dispersal and migration are superficially similar large‐scale movements, but which appear to differ in terms of inter‐individual behavioural synchronization. Seasonal migration is a striking example of coordinated behaviour, enabling animal populations to track spatio‐temporal variation in ecological conditions. By contrast, for dispersal, while social context may influence an individual's emigration and settlement decisions, transience is believed to be mostly a solitary behaviour. Here, we review differences in drivers that may explain why migration appears to be more synchronized than dispersal. We derive the prediction that the contrast in the importance of behavioural synchronization between dispersal and migration is linked to differences in the selection pressures that drive their respective evolution. Although documented examples of collective dispersal are rare, this behaviour may be more common than currently believed, with important consequences for eco‐evolutionary dynamics. Crucially, to date, there is little available theory for predicting when we should expect collective dispersal to evolve, and we also lack empirical data to test predictions across species. By reviewing the state of the art in research on migration and collective movements, we identify how we can harness these advances, both in terms of theory and data collection, to broaden our understanding of synchronized dispersal and its importance in the context of global change.     

Parasite abundance contributes to condition‐dependent dispersal in a wild population of large herbivore

Parasite abundance has been shown to have major consequences for host fitness components such as survival and reproduction. However, although natal dispersal is a key life history trait, whether an individual's decision to disperse or not is influenced by the abundance of parasites it carries remains mostly unknown. Current and opposing hypotheses suggest that infected individuals should either be philopatric to avoid the energetic costs of dispersal (condition dependence) or disperse to escape from heavily parasitised habitats. From intensive monitoring of a roe deer population inhabiting a multi‐use and spatially heterogeneous agricultural landscape, we evaluated the link between an individual's parasite abundance and its propensity to disperse, while accounting for confounding effects of body mass. Dispersal propensity generally decreased with both increasing nematode abundance and with decreasing body mass. Within the dispersing segment of the population, individuals with high nematode abundance left their natal home range later in the season than less parasitised deer. These results clearly show that parasite abundance is an important component of condition‐dependent dispersal in large herbivores. However, unexpectedly, three individuals that were both heavily parasitised and of low body mass dispersed. We suggest that this ‘leave it’ response to high parasite levels in the natal habitat could represent a last ditch attempt to improve reproductive prospects, constituting a form of emergency life history strategy.     

Growth and molecular responses to long‐distance stimuli in poplars: bending vs flame wounding

Inter‐organ communication is essential for plants to coordinate development and acclimate to mechanical environmental fluctuations. The aim of this study was to investigate long‐distance signaling in trees. We compared on young poplars the short‐term effects of local flame wounding and of local stem bending for two distal responses: (1) stem primary growth and (2) the expression of mechanoresponsive genes in stem apices. We developed a non‐contact measurement method based on the analysis of apex images in order to measure the primary growth of poplars. The results showed a phased stem elongation with alternating nocturnal circumnutation phases and diurnal growth arrest phases in Populus tremula × alba clone INRA 717‐1B4. We applied real‐time polymerase chain reaction (RT‐PCR) amplifications in order to evaluate the PtaZFP2, PtaTCH2, PtaTCH4, PtaACS6 and PtaJAZ5 expressions. The flame wounding inhibited primary growth and triggered remote molecular responses. Flame wounding induced significant changes in stem elongation phases, coupled with inhibition of circumnutation. However, the circadian rhythm of phases remained unaltered and the treated plants were always phased with control plants during the days following the stress. For bent plants, the stimulated region of the stem showed an increased PtaJAZ5 expression, suggesting the jasmonates may be involved in local responses to bending. No significant remote responses to bending were observed.