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151.
Lejeune-Hénaut I Hanocq E Béthencourt L Fontaine V Delbreil B Morin J Petit A Devaux R Boilleau M Stempniak JJ Thomas M Lainé AL Foucher F Baranger A Burstin J Rameau C Giauffret C 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2008,116(8):1105-1116
An understanding of the genetic determinism of frost tolerance is a prerequisite for the development of frost tolerant cultivars
for cold northern areas. In legumes, it is not known to which extent vernalization requirement or photoperiod responsiveness
are necessary for the development of frost tolerance. In pea (Pisum sativum L.) however, the flowering locus Hr is suspected to influence winter frost tolerance by delaying floral initiation until after the main winter freezing periods
have passed. The objective of this study was to dissect the genetic determinism of frost tolerance in pea by QTL analysis
and to assess the genetic linkage between winter frost tolerance and the Hr locus. A population of 164 recombinant inbred lines (RILs), derived from the cross Champagne x Terese was evaluated both
in the greenhouse and in field conditions to characterize the photoperiod response from which the allele at the Hr locus was inferred. In addition, the population was also assessed for winter frost tolerance in 11 field conditions. Six
QTL were detected, among which three were consistent among the different experimental conditions, confirming an oligogenic
determinism of frost tolerance in pea. The Hr locus was found to be the peak marker for the highest explanatory QTL of this study. This result supports the hypothesis
of the prominent part played by the photoperiod responsiveness in the determinism of frost tolerance for this species. The
consistency of three QTL makes these positions interesting targets for marker-assisted selection.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
152.
Morin V Sanchez A Quiñones K Huidobro JG Iribarren C Bustos P Puchi M Genevière AM Imschenetzky M 《Journal of cellular physiology》2008,216(3):790-795
We have previously reported that sperm histones (SpH) degradation after fertilization is catalyzed by a cystein-protease (SpH-protease). Its inhibition blocks the degradation of SpH in vivo and also aborts sea urchin development at the initial embryonic cell cycles. It remains unknown if this effect is a consequence of the persistence of SpH on zygotic chromatin, or if this protease is involved per-se in the progression of the embryonic cell cycles. To discriminate among these two options we have inhibited this protease at a time when male chromatin remodeling was completed and the embryos were engaged in the second cell cycle of the cleavage divisions. The role of this enzyme in cell cycle was initially analyzed by immuno-inhibiting its SpH degrading activity in one of the two blastomeres after the initial cleavage division, while the other blastomere was used as a control. We found that in the blastomere injected with the anti-SpH-protease antibodies the cytokinesis was arrested, the chromatin failed to decondense after mitosis and BrdU incorporation into DNA was blocked. Since the N-terminal sequence and the SpH protease was homologous to the cathepsin L (Cat L) family of proteases, we subsequently investigated if the deleterious effect of the inhibition of this protease is related to its Cat L activity. In this context we analyzed the effect of Cat L inhibitor I (Z-Phe-Phe-CH(2)F) on embryonic development. We found that the addition of 100 uM of this inhibitor to the embryos harvested at the time of the initial cleavage division (80 min p.i.) mimics perfectly the effects of the immuno-inhibition of this enzyme obtained by microinjecting the anti-SpH-protease antibodies. Taken together these results indicate that the activity of this protease is required for embryonic cell cycle progression. Interestingly, we observed that when this protease was inhibited the chromatin decondensation after mitosis was abolished indicating that the inhibition of this enzyme affects chromosomes decondensation after mitosis. 相似文献
153.
Pascreau G Delcros JG Morin N Prigent C Arlot-Bonnemains Y 《Developmental biology》2008,317(2):523-530
Xenopus laevis Aurora-A is phosphorylated in vivo onto three amino acids: Ser53, Thr295 and Ser349. The activation of the kinase depends on its autophosphorylation on Thr295 within the T-loop. The phosphorylation of Ser53 by still unknown kinase(s) prevents its degradation. The present work focused on the regulation of Aurora-A function via Ser349 phosphorylation. Mutagenesis of Ser349 to alanine (S349A) had few impact in vitro on the capability of the kinase to autophosphorylate as well as on its activity. These data in addition to in gel kinase assays and site-specific proteolytic digestion experiments prove that Ser349 is clearly neither a primary autophosphorylation site, nor an autophosphorylation site depending on the priming phosphorylation of Thr295. Using specific antibodies, we also show that the phosphorylation of Aurora-A Ser349 is a physiological event during Xenopus oocyte maturation triggered by progesterone. A peak of phosphorylation paralleled the decrease of Aurora activity observed between meiosis I and II. In response to progesterone, X. laevis stage VI oocytes microinjected with the Aurora-A S349A mutant proceeded normally to germinal vesicle breakdown (GVBD), but degenerated rapidly soon after. Since phosphorylation of Ser349 is responsible for a decrease in kinase activity, our results suggest that a down-regulation of Aurora-A activity involving Ser349 phosphorylation is required in the process of maturation. 相似文献
154.
Roger Miras Isabelle Morin Florent Guillain Elisabeth Mintz 《Journal of biological inorganic chemistry》2008,13(2):195-205
Copper is both an essential element as a catalytic cofactor and a toxic element because of its redox properties. Once in the
cell, Cu(I) binds to glutathione (GSH) and various thiol-rich proteins that sequester and/or exchange copper with other intracellular
components. Among them, the Cu(I) chaperone Atx1 is known to deliver Cu(I) to Ccc2, the Golgi Cu–ATPase, in yeast. However,
the mechanism for Cu(I) incorporation into Atx1 has not yet been unraveled. We investigated here a possible role of GSH in
Cu(I) binding to Atx1. Yeast Atx1 was expressed in Escherichia coli and purified to study its ability to bind Cu(I). We found that with an excess of GSH [at least two GSH/Cu(I)], Atx1 formed
a Cu(I)-bridged dimer of high affinity for Cu(I), containing two Cu(I) and two GSH, whereas no dimer was observed in the absence
of GSH. The stability constants (log β) of the Cu(I) complexes measured at pH 6 were 15–16 and 49–50 for CuAtx1 and Cu2I(GS−)2(Atx1)2, respectively. Hence, these results suggest that in vivo the high GSH concentration favors Atx1 dimerization and that Cu2I(GS−)2(Atx1)2 is the major conformation of Atx1 in the cytosol. 相似文献
155.
Andrews GL Tanglao S Farmer WT Morin S Brotman S Berberoglu MA Price H Fernandez GC Mastick GS Charron F Kidd T 《Development (Cambridge, England)》2008,135(23):3839-3848
Developing axons are attracted to the CNS midline by Netrin proteins and other as yet unidentified signals. Netrin signals are transduced in part by Frazzled (Fra)/DCC receptors. Genetic analysis in Drosophila indicates that additional unidentified receptors are needed to mediate the attractive response to Netrin. Analysis of Bolwig's nerve reveals that Netrin mutants have a similar phenotype to Down Syndrome Cell Adhesion Molecule (Dscam) mutants. Netrin and Dscam mutants display dose sensitive interactions, suggesting that Dscam could act as a Netrin receptor. We show using cell overlay assays that Netrin binds to fly and vertebrate Dscam, and that Dscam binds Netrin with the same affinity as DCC. At the CNS midline, we find that Dscam and its paralog Dscam3 act redundantly to promote midline crossing. Simultaneous genetic knockout of the two Dscam genes and the Netrin receptor fra produces a midline crossing defect that is stronger than the removal of Netrin proteins, suggesting that Dscam proteins also function in a pathway parallel to Netrins. Additionally, overexpression of Dscam in axons that do not normally cross the midline is able to induce ectopic midline crossing, consistent with an attractive receptor function. Our results support the model that Dscam proteins function as attractive receptors for Netrin and also act in parallel to Frazzled/DCC. Furthermore, the results suggest that Dscam proteins have the ability to respond to multiple ligands and act as receptors for an unidentified midline attractive cue. These functions in axon guidance have implications for the pathogenesis of Down Syndrome. 相似文献
156.
157.
Morissette M Le Saux M D'Astous M Jourdain S Al Sweidi S Morin N Estrada-Camarena E Mendez P Garcia-Segura LM Di Paolo T 《The Journal of steroid biochemistry and molecular biology》2008,108(3-5):327-338
Clinical and experimental studies show a modulatory role of estrogens in the brain and suggest their beneficial action in mental and neurodegenerative diseases. The estrogen receptors ER and ERβ are present in the brain and their targeting could bring selectivity and reduced risk of cancer. Implication of ERs in the effect of estradiol on dopamine, opiate and glutamate neurotransmission is reviewed. The ER agonist, PPT, is shown as estradiol to modulate hippocampal NMDA receptors and AMPA receptors in cortex and striatum of ovariectomized rats whereas the ERβ agonist DPN is inactive. Striatal DPN activity suggests implication of ERβ in estradiol modulation of D2 receptors and transporters in ovariectomized rats and is supported by the lack of effect of estradiol in ERβ knockout (ERKOβ) mice. Both ER and ERβ agonists modulate striatal preproenkephalin (PPE) gene expression in ovariectomized rats. In male mice PPT protects against MPTP toxicity to striatal dopamine; this implicates Akt/GSK3β signaling and the apoptotic regulators Bcl2 and Bad. This suggests a role for ER in striatal dopamine neuroprotection. ERKO mice are more susceptible to MPTP toxicity and not protected by estradiol; differences in ERKOβ mice are subtler. These results suggest therapeutic potential for the brain of ER specific agonists. 相似文献
158.
Corte JR Fang T Pinto DJ Han W Hu Z Jiang XJ Li YL Gauuan JF Hadden M Orton D Rendina AR Luettgen JM Wong PC He K Morin PE Chang CH Cheney DL Knabb RM Wexler RR Lam PY 《Bioorganic & medicinal chemistry letters》2008,18(9):2845-2849
Introduction of the phenyl piperidinone and phenyl pyridinone P4 moieties in the anthranilamide scaffold led to potent, selective, and orally bioavailable inhibitors of factor Xa. Anthranilamide 28 displayed comparable efficacy to apixaban in the rabbit arteriovenous-shunt (AV) thrombosis model. 相似文献
159.
We tested (1) if the size of dominant species influenced ecosystem functioning in food webs consisting of bacteria, algae, and protozoa; (2) whether those effects changed in importance through time; and (3) how those effects compared with differences in diversity among experimental food webs. We constructed food webs using two size fractions of organisms that differed in individual mass by approximately two orders of magnitude. We measured total biomass and respiration (total CO2 production) as two aspects of ecosystem functioning. We also compared these size‐dependent patterns in functioning across two levels of species richness. Initially, organism size strongly influenced total community biomass. With time, however, biomass and respiration eventually converged in communities dominated by large or small species. We conclude that after sufficient time for community development any differences in ecosystem functioning resulted from differences in community composition, including species richness, but not the size of the dominant organisms. 相似文献
160.
We conducted a short-term microcosm experiment to study the direct and indirect effects of a bacterivore on bacteria and the dynamics of two species of green algae. We introduced Scenedesmus , Chlorella and Colpidium , a bacterivorous ciliate, successively in a carbon-rich medium. Bacteria were introduced with Scenedesmus , Chlorella and Colpidium . The experiment lasted 40 days, preventing us from detecting whether the populations had reached equilibrium. The bacterivore had a positive effect on both species of algae by limiting the abundance of bacteria. In absence of the bacterivore, bacteria did not exclude the two algal species, despite the high carbon:nutrient ratio of the medium. Unexpectedly, by the end of the experiment the bacterivore declined in all microcosms. Also, Chlorella growth was impeded by the presence of Scenedesmus . These two observations might be explained by allelopathic interactions. Our experiment suggests that the functioning of such a simple community is far more complex than assumed in previous theoretical and experimental models. Studying the dynamics of the system, however, allowed us to disentangle species interactions. 相似文献