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21.
Alexandra Seguin Robert Sutak Anne-Laure Bulteau Richard Garcia-Serres Jean-Louis Oddou Sophie Lefevre Renata Santos Andrew Dancis Jean-Michel Camadro Jean-Marc Latour Emmanuel Lesuisse 《生物化学与生物物理学报:疾病的分子基础》2010,1802(6):531-538
Yeast cells deficient in the yeast frataxin homolog (Yfh1p) accumulate iron in their mitochondria. Whether this iron is toxic, however, remains unclear. We showed that large excesses of iron in the growth medium did not inhibit growth and did not decrease cell viability. Increasing the ratio of mitochondrial iron-to-Yfh1p by decreasing the steady-state level of Yfh1p to less than 100 molecules per cell had very few deleterious effects on cell physiology, even though the mitochondrial iron concentration greatly exceeded the iron-binding capacity of Yfh1p in these conditions. Mössbauer spectroscopy and FPLC analyses of whole mitochondria or of isolated mitochondrial matrices showed that the chemical and biochemical forms of the accumulated iron in mitochondria of mutant yeast strains (Δyfh1, Δggc1 and Δssq1) displayed a nearly identical distribution. This was also the case for Δggc1 cells, in which Yfh1p was overproduced. In these mitochondria, most of the iron was insoluble, and the ratio of soluble-to-insoluble iron did not change when the amount of Yfh1p was increased up to 4500 molecules per cell. Our results do not privilege the hypothesis of Yfh1p being an iron storage protein in vivo. 相似文献
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Virginie Rougeron Thierry De Mee?s Sandrine Kako Ouraga Mallorie Hide Anne-Laure Ba?uls 《PLoS pathogens》2010,6(8)
Leishmaniases remain a major public health problem today (350 million people at risk, 12 million infected, and 2 million new infections per year). Despite the considerable progress in cellular and molecular biology and in evolutionary genetics since 1990, the debate on the population structure and reproductive mode of Leishmania is far from being settled and therefore deserves further investigation. Two major hypotheses coexist: clonality versus sexuality. However, because of the lack of clear evidence (experimental or biological confirmation) of sexuality in Leishmania parasites, until today it has been suggested and even accepted that Leishmania species were mainly clonal with infrequent genetic recombination (see [1] for review). Two recent publications, one on Leishmania major (an in vitro experimental study) and one on Leishmania braziliensis (a population genetics analysis), once again have challenged the hypothesis of clonal reproduction. Indeed, the first study experimentally evidenced genetic recombination and proposed that Leishmania parasites are capable of having a sexual cycle consistent with meiotic processes inside the insect vector. The second investigation, based on population genetics studies, showed strong homozygosities, an observation that is incompatible with a predominantly clonal mode of reproduction at an ecological time scale (∼20–500 generations). These studies highlight the need to advance the knowledge of Leishmania biology. In this paper, we first review the reasons stimulating the continued debate and then detail the next essential steps to be taken to clarify the Leishmania reproduction model. Finally, we widen the discussion to other Trypanosomatidae and show that the progress in Leishmania biology can improve our knowledge of the evolutionary genetics of American and African trypanosomes. 相似文献
27.
The intra-annual variability of soft-bottom macrobenthos abundance patterns in the North Channel of the Seine estuary 总被引:2,自引:0,他引:2
Nicolas Desroy Anne-Laure Janson Lionel Denis Gregory Charrier Sandric Lesourd Jean-Claude Dauvin 《Hydrobiologia》2007,588(1):173-188
Temporal and spatial variability of the Abra alba–Pectinaria koreni and Macoma balthica communities was examined in the northern part of the Seine estuary (North Channel) over different space and time scales in
order to assess the role that the hydrologic regime and/or anthropogenic influences play in defining benthic communities over
time. Sediment in the North Channel displayed strong spatial and temporal variability, sustained by intense sediment transport
episodes. Total macrobenthic abundances ranged widely on the course of the year and there was no evidence of a seasonal signal
for the density fluctuations, whatever the spatial scale considered. The bio-sedimentary dynamics can be divided into two
periods: the first corresponds to the high flow rate period (January–May) during which fauna is influenced by fine silt/clay
deposition, and the second to the low flow rate period (June–December) during which sandy deposits prevail. Despite the absence
of significant correlations between sediment composition and abundance, episodes of sediment transport seem to be an important
structuring mechanism in the Seine estuary. As a consequence, the faunal composition varied throughout the year. The winter
and spring fauna, characterised by species living on muddy fine-sands or muds, were enriched during the summer and autumn
by species living in clean fine sand, such as Donax vittatus, Nephtys cirrosa or Spio decoratus, mainly represented by adult individuals. Secondary settlement of drifters may explain the rapid structuration of assemblages
a few days after the sandy deposits. Our results suggest the importance of the bentho-pelagic coupling, primarily induced
by the sedimentary instability, on the macrobenthic fauna dynamics. The intra-annual variability of assemblages at the mouth
of the Seine river and the silted situation of the North Channel might simply be the result of the silting up and alteration
of the inner estuary, generated by several decades of man-made modifications and natural processes. 相似文献
28.
Turcot-Dubois AL Le Moullac-Vaidye B Despiau S Roubinet F Bovin N Le Pendu J Blancher A 《Glycobiology》2007,17(5):516-528
Functional glycosyltransferase 6 (GT6) family members catalyze the transfer of galactose or N-acetylgalactosamine in alpha1,3 linkage to various substrates and synthesize structures related to the A and B histo-blood group antigens, the Forssman antigen, alphaGal epitope, and iGb3 glycolipid. In rat, mouse, dog, and cow genomes, we have identified three new mammalian genes (GT6m5, GT6m6, and GT6m7) encoding putative proteins belonging to the GT6 family. Among these, GT6m6 protein does not display major alterations of the GT6 motifs involved in binding of the divalent cation and the substrate. Based on protein sequence comparison, gene structure, and synteny, GT6 homologous sequences were also identified in bird, fish, and amphibian genomes. Strikingly, the number and type of GT6 genes varied widely from species to species, even within phylogenetically related groups. In human, except ABO functional alleles, all other GT6 genes are either absent or nonfunctional. Human, mouse, and cow have only one ABO gene, whereas rat and dog have several. In the chicken, the Forssman synthase-like is the single GT6 family member. Five Forssman synthase-like genes were found in zebrafish, but are absent from three other fishes (fugu, puffer fish, and medaka). Two iGb3 synthase-like genes were found in medaka, which are absent from zebrafish. Fugu, puffer fish, and medaka have an additional GT6 gene that we termed GT6m8, which is absent from all other species analyzed here. These observations indicate that individual GT6 genes have expanded and contracted by recurrent duplications and deletions during vertebrate evolution, following a birth-and-death evolution type. 相似文献
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Marie-Elodie Cattin Jessica Wang Jonathan J. Weldrick Cassandra L. Roeske Esther Mak Stephanie L. Thorn Jean N. DaSilva Yibin Wang Aldon J. Lusis Patrick G. Burgon 《The Journal of biological chemistry》2015,290(44):26699-26714
Aging and diseases generally result from tissue inability to maintain homeostasis through adaptation. The adult heart is particularly vulnerable to disequilibrium in homeostasis because its regenerative abilities are limited. Here, we report that MLIP (muscle enriched A-type lamin-interacting protein), a unique protein of unknown function, is required for proper cardiac adaptation. Mlip−/− mice exhibited normal cardiac function despite myocardial metabolic abnormalities and cardiac-specific overactivation of Akt/mTOR pathways. Cardiac-specific MLIP overexpression led to an inhibition of Akt/mTOR, providing evidence of a direct impact of MLIP on these key signaling pathways. Mlip−/− hearts showed an impaired capacity to adapt to stress (isoproterenol-induced hypertrophy), likely because of deregulated Akt/mTOR activity. Genome-wide association studies showed a genetic association between Mlip and early response to cardiac stress, supporting the role of MLIP in cardiac adaptation. Together, these results revealed that MLIP is required for normal myocardial adaptation to stress through integrated regulation of the Akt/mTOR pathways. 相似文献
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