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91.
Jean Peccoud Manon de la Huerta Joël Bonhomme Cindy Laurence Yannick Outreman Carole M. Smadja Jean‐Christophe Simon 《Evolution; international journal of organic evolution》2014,68(10):2983-2995
Linking adaptive divergence to hybrid unfitness is necessary to understand the ecological factors contributing to reproductive isolation and speciation. To date, this link has been demonstrated in few model systems, most of which encompass ecotypes that occupy relatively early stages in the speciation process. Here we extend these studies by assessing how host‐plant adaptation conditions hybrid fitness in the pea aphid, Acyrthosiphon pisum. We made crosses between and within five pea aphid biotypes adapted to different host plants and representing various stages of divergence within the complex. Performance of F1 hybrids and nonhybrids was assessed on a “universal” host that is favorable to all pea aphid biotypes in laboratory conditions. Although hybrids performed equally well as nonhybrids on the universal host, their performance was much lower than nonhybrids on the natural hosts of their parental populations. Hence, hybrids, rather than being intrinsically deficient, are maladapted to their parents’ hosts. Interestingly, the impact of this maladaptation was stronger in certain hybrids from crosses involving the most divergent biotype, suggesting that host‐dependent postzygotic isolation has continued to evolve late in divergence. Even though host‐independent deficiencies are not excluded, hybrid maladaptation to parental hosts supports the hypothesis of ecological speciation in this complex. 相似文献
92.
Attoumbré J Charlet S Baltora-Rosset S Hano C Raynaud-Le Grandic S Gillet F Bensaddek L Mesnard F Fliniaux MA 《Plant cell reports》2006,25(8):859-864
As flaxseed mainly accumulates lignans (secoisolariciresinol diglucoside and matairesinol), these compounds were barely or not detected in plant cell suspensions initiated from Linum usitatissimum. In contrast, these cell suspensions were shown to accumulate substantial amounts of a neolignan identified as dehydrodiconiferyl alcohol-4-β-d-glucoside (DCG) (up to 47.7 mg g−1 DW). The formation of this pharmacologically active compound was evaluated as a function of cell growth and in relation to phytohormone balance of the culture media. After establishment of efficient culture conditions, production of DCG was investigated in immobilized plant cell suspensions initiated from plantlet roots of L. usitatissimum. The results indicate that immobilization enhances the DCG production up to 60.0 mg g−1 DW but depresses the cell growth resulting in no improvement of the total DCG yield. Nevertheless, with immobilized cell suspensions, a release of DCG into the medium is observed allowing an easier recovery. 相似文献
93.
Bonyhadi M Frohlich M Rasmussen A Ferrand C Grosmaire L Robinet E Leis J Maziarz RT Tiberghien P Berenson RJ 《Journal of immunology (Baltimore, Md. : 1950)》2005,174(4):2366-2375
Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of leukemic B cells concomitant with immunological abnormalities and depressed immune responses. The T cell abnormalities found in CLL patients are thought to increase the risk of infection and hamper immune recognition and elimination of leukemic cells. We evaluated whether providing signals through CD3 and CD28 would correct some of these T cell defects. PBMC were incubated with anti-CD3 and anti-CD28 mAbs conjugated to superparamagnetic beads for 12-14 days. This resulted in a 1400-fold increase in T cell numbers. Activated T cells expressed high levels of CD25, CD54, CD137, and CD154, and produced IFN-gamma, TNF-alpha, and GM-CSF. The mean T cell composition of cultures increased from approximately 6% to >90% and leukemic B cells decreased from a mean of approximately 85% to 0.1% or less. Leukemic B cells up-regulated expression of CD54, CD80, CD86, and CD95. Receptor up-regulation required direct cell contact with the activated T cells and could be blocked with anti-CD154 mAb, suggesting that the CD40-CD40L pathway helped mediate these effects. Poor T cell responses to allostimulation were corrected by the activation and expansion process. The skewing in the TCR repertoire returned to normal, or near normal following the culture process in eight of nine patients with abnormal TCR repertoires. Activated T cells had potent in vitro antileukemic effects in contrast to nonactivated T cells. Based upon these findings, a clinical trial has been initiated to test the potential therapeutic effects of T cells activated using this approach in patients with CLL. 相似文献
94.
Alban Franco Aude Jouaux Michel Mathieu Pascal Sourdaine Christophe Lelong Kristell Kellner Clothilde Heude Berthelin 《Cell and tissue research》2010,340(1):201-210
To understand the processes involved in tissue remodeling associated with the seasonal reproductive cycle of the oyster Crassostrea gigas, we used immunodetection and expression measurements of proliferating cell nuclear antigen (PCNA). The expression of the
PCNA gene was measured by real-time polymerase chain reaction in the whole gonadal area compared with laser microdissected
gonad and storage tissue. Results underlined the advantage of the laser microdissection approach to detect expression, mainly
for early stages of spermatogenesis. In the storage tissue, PCNA expression was reduced in the gonadal tubules, but immunolabeled
hemocytes and vesicular cells were detected when the storage tissue was being restored. In the gonadal tubules, the PCNA gene
was more highly expressed in males than in females. As soon as spermatogenesis was initiated, PCNA expression showed a high
and constant level. In females, the expression level increased gradually until the ripe stage. The immunological approach
established the involvement of peritubular cells in gonadal tubule expansion during early gametogenesis. In both sexes, gonial
mitosis was immunodetected throughout the reproductive cycle. In males, the occurrence of two types of spermatogonia was ascertained
by differential immunolabeling, and intragonadal somatic cell proliferation was noted. As expected, immunolabeling was never
observed from stage II spermatocytes to spermatozoa. In females, positively stained cells were detected from oogonia to growing
oocytes with various labeled intracellular locations. 相似文献
95.
BACTIBASE second release: a database and tool platform for bacteriocin characterization 总被引:2,自引:0,他引:2
Riadh Hammami Abdelmajid Zouhir Christophe Le Lay Jeannette Ben Hamida Ismail Fliss 《BMC microbiology》2010,10(1):22
Background
BACTIBASE is an integrated open-access database designed for the characterization of bacterial antimicrobial peptides, commonly known as bacteriocins. 相似文献96.
97.
Emilia Moreno-Ruiz Marta Galán-Díez Weidong Zhu Elena Fernández-Ruiz Christophe d'Enfert Scott G. Filler Pascale Cossart Esteban Veiga 《Cellular microbiology》2009,11(8):1179-1189
Candida albicans is a major cause of oropharyngeal, vulvovaginal and haematogenously disseminated candidiasis. Endocytosis of C. albicans hyphae by host cells is a prerequisite for tissue invasion. This internalization involves interactions between the fungal invasin Als3 and host E- or N-cadherin. Als3 shares some structural similarity with InlA, a major invasion protein of the bacterium Listeria monocytogenes . InlA mediates entry of L. monocytogenes into host cells through binding to E-cadherin. A role in internalization, for a non-classical stimulation of the clathrin-dependent endocytosis machinery, was recently highlighted. Based on the similarities between the C. albicans and L. monocytogenes invasion proteins, we studied the role of clathrin in the internalization of C. albicans . Using live-cell imaging and indirect immunofluorescence of epithelial cells infected with C. albicans , we observed that host E-cadherin, clathrin, dynamin and cortactin accumulated at sites of C. albicans internalization. Similarly, in endothelial cells, host N-cadherin, clathrin and cortactin accumulated at sites of fungal endocytosis. Furthermore, clathrin, dynamin or cortactin depletion strongly inhibited C. albicans internalization by epithelial cells. Finally, beads coated with Als3 were internalized in a clathrin-dependent manner. These data indicate that C. albicans , like L. monocytogenes, hijacks the clathrin-dependent endocytic machinery to invade host cells. 相似文献
98.
David Kaniewski Elise Van Campo Christophe Morhange Jo?l Guiot Dov Zviely Sabine Le Burel Thierry Otto Michal Artzy 《PloS one》2014,9(7)
Although human activity is considered to be a major driving force affecting the distribution and dynamics of Mediterranean ecosystems, the full consequences of projected climate variability and relative sea-level changes on fragile coastal ecosystems for the next century are still unknown. It is unclear how these waterfront ecosystems can be sustained, as well as the services they provide, when relative sea-level rise and global warming are expected to exert even greater pressures in the near future (drought, habitat degradation and accelerated shoreline retreat). Haifa Bay, northern Israel, has recorded a landward sea invasion, with a maximum sea penetration 4,000 years ago, during an important period of urban development and climate instability. Here, we examine the cumulative pressure of climate shifts and relative sea-level changes in order to investigate the patterns and mechanisms behind forest replacement by an open-steppe. We provide a first comprehensive and integrative study for the southern Levant that shows that (i) human impact, through urbanization, has been the main driver behind ecological erosion in the past 4,000 years; (ii) climate pressures have reinforced this impact; and (iii) local coastal changes have played a decisive role in eroding ecosystem resilience. These three parameters, which have closely interacted during the last 4,000 years in Haifa Bay, clearly indicate that for an efficient management of the coastal habitats, anthropogenic pressures linked to urban development must be reduced in order to mitigate the predicted effects of Global Change. 相似文献
99.
Morisseau C Bernay M Escaich A Sanborn JR Lango J Hammock BD 《Analytical biochemistry》2011,(1):154-162
The microsomal epoxide hydrolase (mEH) plays a significant role in the metabolism of numerous xenobiotics. In addition, it has a potential role in sexual development and bile acid transport, and it is associated with a number of diseases such as emphysema, spontaneous abortion, eclampsia, and several forms of cancer. Toward developing chemical tools to study the biological role of mEH, we designed and synthesized a series of absorbent and fluorescent substrates. The highest activity for both rat and human mEH was obtained with the fluorescent substrate cyano(6-methoxy-naphthalen-2-yl)methyl glycidyl carbonate (11). An in vitro inhibition assay using this substrate ranked a series of known inhibitors similarly to the assay that used radioactive cis-stilbene oxide but with a greater discrimination between inhibitors. These results demonstrate that the new fluorescence-based assay is a useful tool for the discovery of structure–activity relationships among mEH inhibitors. Furthermore, this substrate could also be used for the screening chemical library with high accuracy and with a Z′ value of approximately 0.7. This new assay permits a significant decrease in labor and cost and also offers the advantage of a continuous readout. However, it should not be used with crude enzyme preparations due to interfering reactions. 相似文献
100.
Reimann S Grattepanche F Benz R Mozzetti V Rezzonico E Berger B Lacroix C 《Bioresource technology》2011,102(6):4559-4567
The effect of cell immobilization and continuous culture was studied on selected physiological and technological characteristics of Bifidobacterium longum NCC2705 cultivated for 20 days in a two stage continuous fermentation system. Continuous immobilized cell (IC) cultures with and without glucose limitation exhibited formation of macroscopic cell aggregates after 12 and 9 days, respectively. Auto-aggregation resulted in underestimation of viable cell counts by plate counts by more than 2 log units CFU/ml compared with qPCR method. Modifications of cell membrane composition might partially explain aggregate formation in IC cultures. Decreases in the ratio of unsaturated to saturated fatty acid content from 1.74 to 0.58 might also contribute to the enhanced tolerance of IC cells to porcine bile salts and aminoglycosidic antibiotics compared with free cells from batch cultures.The enhanced resistance against bile salts in combination with auto-aggregation may confer an advantage to probiotic bacteria produced by IC technology. 相似文献