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1.
Dr. Olivier Kah Pierrette Dubourg Brigitte Onteniente Michel Geffard André Calas 《Cell and tissue research》1986,244(3):577-582
Summary The dopaminergic innervation of the goldfish pituitary gland was studied by immunocytochemistry at the electron-microscope level using highly specific antibodies against dopamine coupled to bovine serum albumin with glutaraldehyde. A satisfactory preservation of the tissue was achieved after immersion in 5% glutaraldehyde in phosphate buffer containing sodium metabisulfite to prevent oxidation of the endogenous dopamine. The immunocyto-chemical procedure was performed on Vibratome sections using the preembedding method. Immunoreactivity was restricted to part of the neurosecretory type-B fibers (diameter of the secretory vesicles lower than 100 nm) in which it was found to occupy the whole cytoplasm. Labeled fibers were observed within the neurohypophysis in the different parts of the gland and in the adenohypophyseal tissue where immunoreactive profiles were detected in close apposition to the different cell types. These data are in agreement with previous results obtained by means of radioautography and further support a role for dopamine in the neuroendocrine regulation of pituitary functions in teleosts. 相似文献
2.
Dimethylsulfoxide (DMSO) acts on dark- and light-induced movements exhibited by leaflets of isolated leaves of Cassia fasciculate Michx. The closing movement (scotonasty), induced when the leaves are placed in darkness during the normal period of daylight, was inhibited, whereas the opening movement (photonasty), when the leaves arc transferred to light during the normal period of darkness, was promoted. The concentration for significant effects of DMSO was 1% (v/v) when applied over a 3-h period. After five days, a necrosis of the leaflets was observed for DMSO concentrations as small as 0.1%, applied over a 6-h period. Complete abscission took place if 3% DMSO was applied for more than 30 min. 相似文献
3.
Jacques Diezi Pierrette Michoud-Hausel Nicole Nicolas-Buxcel 《The Yale journal of biology and medicine》1978,51(3):265-270
Two to 4 hours after unilateral renal exclusion in rats, urine flow rate from the remaining kidney had increased to twice the control level, whereas the filtration rate remained unchanged. After contralateral nephrectomy, NGFR was similar to that of controls, but fractional water reabsorption along proximal tubules decreased. Protein concentration in efferent arteriolar plasma, and hydrostatic pressure gradient between proximal tubules and peritubular capillaries were similar in experimental and control kidneys. Unilateral renal exclusion was followed by a rapid increase of blood pressure. Prevention of this rise depressed but did not abolish functional compensatory adaptation. The occurrence of compensatory adaptation was not affected by decreased renal perfusion pressure. 相似文献
4.
Muriel Mazet Pauline Morand Marc Biran Guillaume Bouyssou Pierrette Courtois Sylvie Daulouède Yoann Millerioux Jean-Michel Franconi Philippe Vincendeau Patrick Moreau Frédéric Bringaud 《PLoS neglected tropical diseases》2013,7(12)
Background
The bloodstream forms of Trypanosoma brucei, the causative agent of sleeping sickness, rely solely on glycolysis for ATP production. It is generally accepted that pyruvate is the major end-product excreted from glucose metabolism by the proliferative long-slender bloodstream forms of the parasite, with virtually no production of succinate and acetate, the main end-products excreted from glycolysis by all the other trypanosomatid adaptative forms, including the procyclic insect form of T. brucei.Methodology/Principal Findings
A comparative NMR analysis showed that the bloodstream long-slender and procyclic trypanosomes excreted equivalent amounts of acetate and succinate from glucose metabolism. Key enzymes of acetate production from glucose-derived pyruvate and threonine are expressed in the mitochondrion of the long-slender forms, which produces 1.4-times more acetate from glucose than from threonine in the presence of an equal amount of both carbon sources. By using a combination of reverse genetics and NMR analyses, we showed that mitochondrial production of acetate is essential for the long-slender forms, since blocking of acetate biosynthesis from both carbon sources induces cell death. This was confirmed in the absence of threonine by the lethal phenotype of RNAi-mediated depletion of the pyruvate dehydrogenase, which is involved in glucose-derived acetate production. In addition, we showed that de novo fatty acid biosynthesis from acetate is essential for this parasite, as demonstrated by a lethal phenotype and metabolic analyses of RNAi-mediated depletion of acetyl-CoA synthetase, catalyzing the first cytosolic step of this pathway.Conclusions/Significance
Acetate produced in the mitochondrion from glucose and threonine is synthetically essential for the long-slender mammalian forms of T. brucei to feed the essential fatty acid biosynthesis through the “acetate shuttle” that was recently described in the procyclic insect form of the parasite. Consequently, key enzymatic steps of this pathway, particularly acetyl-CoA synthetase, constitute new attractive drug targets against trypanosomiasis. 相似文献5.
Géraldine De Muylder Sylvie Daulouède Laurence Lecordier Pierrick Uzureau Yannick Morias Jan Van Den Abbeele Guy Caljon Michel Hérin Philippe Holzmuller Silla Semballa Pierrette Courtois Luc Vanhamme Beno?t Stijlemans Patrick De Baetselier Michael P. Barrett Jillian L. Barlow Andrew N. J. McKenzie Luke Barron Thomas A. Wynn Alain Beschin Philippe Vincendeau Etienne Pays 《PLoS pathogens》2013,9(10)
Background
In order to promote infection, the blood-borne parasite Trypanosoma brucei releases factors that upregulate arginase expression and activity in myeloid cells.Methodology/Principal findings
By screening a cDNA library of T. brucei with an antibody neutralizing the arginase-inducing activity of parasite released factors, we identified a Kinesin Heavy Chain isoform, termed TbKHC1, as responsible for this effect. Following interaction with mouse myeloid cells, natural or recombinant TbKHC1 triggered SIGN-R1 receptor-dependent induction of IL-10 production, resulting in arginase-1 activation concomitant with reduction of nitric oxide (NO) synthase activity. This TbKHC1 activity was IL-4Rα-independent and did not mirror M2 activation of myeloid cells. As compared to wild-type T. brucei, infection by TbKHC1 KO parasites was characterized by strongly reduced parasitaemia and prolonged host survival time. By treating infected mice with ornithine or with NO synthase inhibitor, we observed that during the first wave of parasitaemia the parasite growth-promoting effect of TbKHC1-mediated arginase activation resulted more from increased polyamine production than from reduction of NO synthesis. In late stage infection, TbKHC1-mediated reduction of NO synthesis appeared to contribute to liver damage linked to shortening of host survival time.Conclusion
A kinesin heavy chain released by T. brucei induces IL-10 and arginase-1 through SIGN-R1 signaling in myeloid cells, which promotes early trypanosome growth and favors parasite settlement in the host. Moreover, in the late stage of infection, the inhibition of NO synthesis by TbKHC1 contributes to liver pathogenicity. 相似文献6.
Simionato E Barrios N Duloquin L Boissonneau E Lecorre P Agnès F 《Developmental biology》2007,301(1):166-177
Drosophila ELAV is the founding member of an evolutionarily conserved family of RNA-binding proteins considered as key inducers of neuronal differentiation. Although several ELAV-specific targets have been identified, little is known about the role of elav during neural development. Here, we report a detailed characterization of the elav mutant commissural phenotype. The reduced number of commissures in elav mutant embryos is not due to loss or misspecification of neural cells but results from defects in commissural axon projections across the midline. We establish a causal relationship between the elav mutant commissural phenotype and a reduction in the expression of commissureless, a key component of the Robo/Slit growth cone repulsive signalling pathway. In the nerve cord of elav mutant embryos, comm mRNA expression is strongly reduced in neurons, but not in midline glial cells. Furthermore, specific expression of an elav transgene in posterior neurons of each segment of an elav mutant nerve cord restores comm mRNA expression in these cells, as well as the formation of posterior commissures. Finally, forced expression of comm in specific commissural neuron subsets rescues the midline crossing defects of these neurons in elav mutant embryos, further indicating that elav acts cell autonomously on comm expression. 相似文献
7.
P Perrin S Ringeard J Harb K Meflah J Menanteau 《Cell biology international reports》1992,16(12):1237-1245
Mixed cultures of fibroblasts with rat colon carcinoma cell lines were used to investigate the production of extracellular matrix glycoproteins. Tumoral cells were shown to influence their production in different ways depending on the cell clone (PROb cells which in vivo produce progressive tumors and REGb cells which produce regressive ones) but also on the relative proportions of stromal and tumoral cells. When fibroblasts were predominant, the REGb cells containing mixture produced higher levels of all protein studied as compared with the PROb cells containing system. When the situation was reversed in favor of tumoral cells, REGb cells containing cocultures still produced more fibronectin, laminin and undulin, but the difference with PROb ones was reduced. On the opposite, cocultures enriched with PROb cells made more entactin and SPARC and approximately equal amounts of tenascin. 相似文献
8.
Three-dimensional localization of pORF65 in Kaposi's sarcoma-associated herpesvirus capsid
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Of the six herpesvirus capsid proteins, the smallest capsid proteins (SCPs) share the least sequence homology among herpesvirus family members and have been implicated in virus specificity during infection. The herpes simplex virus-1 (HSV-1) SCP was shown to be horn shaped and to specifically bind the upper domain of each major capsid protein in hexons but not in pentons. In Kaposi's sarcoma-associated herpesvirus (KSHV), the protein encoded by the ORF65 gene (pORF65) is the putative SCP but its location remains controversial due to the absence of such horn-shaped densities from both the pentons and hexons of the KSHV capsid reconstructions. To directly locate the KSHV SCP, we have used electron cryomicroscopy and three-dimensional reconstruction techniques to compare the three-dimensional structure of KSHV capsids to that of anti-pORF65 antibody-labeled capsids. Our difference map shows prominent antibody densities bound to the tips of the hexons but not to pentons, indicating that KSHV SCP is attached to the upper domain of the major capsid protein in hexons but not to that in pentons, similar to HSV-1 SCP. The lack of horn-shaped densities on the hexons indicates that KSHV SCP exhibits structural features that are substantially different from those of HSV-1 SCP. The location of SCP at the outermost regions of the capsid suggests a possible role in mediating capsid interactions with the tegument and cytoskeletal proteins during infection. 相似文献
9.
Plasma membrane aquaporins are involved in winter embolism recovery in walnut tree 总被引:7,自引:0,他引:7
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Sakr S Alves G Morillon R Maurel K Decourteix M Guilliot A Fleurat-Lessard P Julien JL Chrispeels MJ 《Plant physiology》2003,133(2):630-641
In perennial plants, freeze-thaw cycles during the winter months can induce the formation of air bubbles in xylem vessels, leading to changes in their hydraulic conductivity. Refilling of embolized xylem vessels requires an osmotic force that is created by the accumulation of soluble sugars in the vessels. Low water potential leads to water movement from the parenchyma cells into the xylem vessels. The water flux gives rise to a positive pressure essential for the recovery of xylem hydraulic conductivity. We investigated the possible role of plasma membrane aquaporins in winter embolism recovery in walnut (Juglans regia). First, we established that xylem parenchyma starch is converted to sucrose in the winter months. Then, from a xylem-derived cDNA library, we isolated two PIP2 aquaporin genes (JrPIP2,1 and JrPIP2,2) that encode nearly identical proteins. The water channel activity of the JrPIP2,1 protein was demonstrated by its expression in Xenopus laevis oocytes. The expression of the two PIP2 isoforms was investigated throughout the autumn-winter period. In the winter period, high levels of PIP2 mRNA and corresponding protein occurred simultaneously with the rise in sucrose. Furthermore, immunolocalization studies in the winter period show that PIP2 aquaporins were mainly localized in vessel-associated cells, which play a major role in controlling solute flux between parenchyma cells and xylem vessels. Taken together, our data suggest that PIP2 aquaporins could play a role in water transport between xylem parenchyma cells and embolized vessels. 相似文献
10.
Oswald IP Desautels C Laffitte J Fournout S Peres SY Odin M Le Bars P Le Bars J Fairbrother JM 《Applied and environmental microbiology》2003,69(10):5870-5874
Fumonisin B(1) (FB(1)) is a mycotoxin that commonly occurs in maize. FB(1) causes a variety of toxic effects in different animal species and has been implicated as a contributing factor of esophageal cancers in humans. In the present study, we examined the effect of dietary exposure to FB(1) on intestinal colonization by pathogenic Escherichia coli associated with extraintestinal infection. Three-week-old weaned pigs were given FB(1) by gavage as a crude extract or as a purified toxin at a dose of 0.5 mg/kg of body weight daily for 6 days. On the last day of the toxin treatment, the pigs were orally inoculated with an extraintestinal pathogenic E. coli strain. All animals were euthanized 24 h later, necropsies were performed, and tissues were taken for bacterial counts and light microscopic examination. Ingestion of FB(1) had only a minimal effect on animal weight gain, did not cause any macroscopic or microscopic lesions, and did not change the plasma biochemical profile. However, colonization of the small and large intestines by an extraintestinal pathogenic E. coli strain was significantly increased. Our results show that FB(1) is a predisposing factor to infectious disease and that the pig can be used as a model for the study of the consequences of ingesting mycotoxin-contaminated food. 相似文献