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31.
When parental females (♀♀P = mothers) of the rotifer Notommata copeus are placed in light conditions inducing the appearance of mictic females in their offspring (F1), the age of the parents of these parental females significantly affects the ratio of mictic females in the F1 generation. The preparental females (♀♀PP = grandmothers), the parental females and the F1 females are isolated in a medium changed at each generation and, in the second experimental series, changed daily: the preparental age effect implicates the transmission of substances on two generations. This influence of the preparental age is rhythmic: the ratio of mictic females in F1 related to this age varies in a sinusoidal manner. This influence is endogenous: it persists, always in a sinusoidal form, when the medium in which each grandmother is placed is changed daily. Furthermore, the net reproduction ratio, Ro, does not vary significantly with the preparental age during these experiments. 相似文献
32.
Bruneel O Volant A Gallien S Chaumande B Casiot C Carapito C Bardil A Morin G Brown GE Personné CJ Le Paslier D Schaeffer C Van Dorsselaer A Bertin PN Elbaz-Poulichet F Arsène-Ploetze F 《Microbial ecology》2011,61(4):793-810
Acid mine drainage of the Carnoulès mine (France) is characterized by acid waters containing high concentrations of arsenic and iron. In the first 30?m along the Reigous, a small creek draining the site, more than 38% of the dissolved arsenic was removed by co-precipitation with Fe(III), in agreement with previous studies, which suggest a role of microbial activities in the co-precipitation of As(III) and As(V) with Fe(III) and sulfate. To investigate how this particular ecosystem functions, the bacterial community was characterized in water and sediments by 16S rRNA encoding gene library analysis. Based on the results obtained using a metaproteomic approach on sediments combined with high-sensitivity HPLC-chip spectrometry, several GroEL orthologs expressed by the community were characterized, and the active members of the prokaryotic community inhabiting the creek sediments were identified. Many of these bacteria are ??-proteobacteria such as Gallionella and Thiomonas, but ??-proteobacteria such as Acidithiobacillus ferrooxidans and ??-proteobacteria such as Acidiphilium, Actinobacteria, and Firmicutes were also detected. 相似文献
33.
Sheung-Tak Cheng Rosanna WL Lau Emily PM Mak Natalie SS Ng Linda CW Lam Helene H Fung Julian CL Lai Timothy Kwok Diana TF Lee 《Trials》2012,13(1):1-10
Background
Patients with ST-elevation myocardial infarction (STEMI) not treated with primary or rescue percutaneous coronary intervention (PCI) are at risk for recurrent ischemia, especially when viability in the infarct-area is present. Therefore, an invasive strategy with PCI of the infarct-related coronary artery in patients with viability would reduce the occurrence of a composite end point of death, reinfarction, or unstable angina (UA).Methods
Patients admitted with an (sub)acute myocardial infarction, who were not treated by primary or rescue PCI, and who were stable during the first 48 hours after the acute event, were screened for the study. Eventually, we randomly assigned 216 patients with viability (demonstrated with low-dose dobutamine echocardiography) to an invasive or a conservative strategy. In the invasive strategy stenting of the infarct-related coronary artery was intended with abciximab as adjunct treatment. Seventy-five (75) patients without viability served as registry group. The primary endpoint was the composite of death from any cause, recurrent myocardial infarction (MI) and unstable angina at one year. As secondary endpoint the need for (repeat) revascularization procedures and anginal status were recorded.Results
The primary combined endpoint of death, recurrent MI and unstable angina was 7.5% (8/106) in the invasive group and 17.3% (19/110) in the conservative group (Hazard ratio 0.42; 95% confidence interval [CI] 0.18-0.96; p = 0.032). During follow up revascularization-procedures were performed in 6.6% (7/106) in the invasive group and 31.8% (35/110) in the conservative group (Hazard ratio 0.18; 95% CI 0.13-0.43; p < 0.0001). A low rate of recurrent ischemia was found in the non-viable group (5.4%) in comparison to the viable-conservative group (14.5%). (Hazard-ratio 0.35; 95% CI 0.17-1.00; p = 0.051).Conclusion
We demonstrated that after acute MI (treated with thrombolysis or without reperfusion therapy) patients with viability in the infarct-area benefit from a strategy of early in-hospital stenting of the infarct-related coronary artery. This treatment results in a long-term uneventful clinical course. The study confirmed the low risk of recurrent ischemia in patients without viability.Trial registration
ClinicalTrials.gov: NCT00149591. 相似文献34.
David Halter Florence Goulhen-Chollet Sébastien Gallien Corinne Casiot Jér?me Hamelin Fran?oise Gilard Dimitri Heintz Christine Schaeffer Christine Carapito Alain Van Dorsselaer Guillaume Tcherkez Florence Arsène-Ploetze Philippe N Bertin 《The ISME journal》2012,6(7):1391-1402
Euglena mutabilis is a photosynthetic protist found in acidic aquatic environments such as peat bogs, volcanic lakes and acid mine drainages (AMDs). Through its photosynthetic metabolism, this protist is supposed to have an important role in primary production in such oligotrophic ecosystems. Nevertheless, the exact contribution of E. mutabilis in organic matter synthesis remains unclear and no evidence of metabolite secretion by this protist has been established so far. Here we combined in situ proteo-metabolomic approaches to determine the nature of the metabolites accumulated by this protist or potentially secreted into an AMD. Our results revealed that the secreted metabolites are represented by a large number of amino acids, polyamine compounds, urea and some sugars but no fatty acids, suggesting a selective organic matter contribution in this ecosystem. Such a production may have a crucial impact on the bacterial community present on the study site, as it has been suggested previously that prokaryotes transport and recycle in situ most of the metabolites secreted by E. mutabilis. Consequently, this protist may have an indirect but important role in AMD ecosystems but also in other ecological niches often described as nitrogen-limited. 相似文献
35.
36.
Heidi Hirsch Laure Gallien Fiona A. C. Impson Catharina Kleinjan David M. Richardson Johannes J. Le Roux 《Biological invasions》2017,19(6):1715-1722
Elaborate and expensive endeavours are underway worldwide to understand and manage biological invasions. However, the success of such efforts can be jeopardised due to taxonomic uncertainty. We highlight how unresolved native range taxonomy can complicate inferences in invasion ecology using the invasive tree Acacia dealbata in South Africa as an example. Acacia dealbata is thought to comprise two subspecies based on morphological characteristics and environmental requirements within its native range in Australia: ssp. dealbata and spp. subalpina. Biological control is the most promising option for managing invasive A. dealbata populations in South Africa, but it remains unknown which genetic/taxonomic entities are present in the country. Resolving this question is crucial for selecting appropriate biological control agents and for identifying areas with the highest invasion risk. We used species distribution models (SDMs) and phylogeographic approaches to address this issue. The ability of subspecies-specific and overall species SDMs to predict occurrences in South Africa was also explored. Furthermore, as non-overlapping bioclimatic niches between the two taxonomic entities may translate into evolutionary distinctiveness, we also tested genetic distances between the entities using DNA sequencing data and network analysis. Both approaches were unable to differentiate the two putative subspecies of A. dealbata. However, the SDM approach revealed a potential niche shift in the non-native range, and DNA sequencing results suggested repeated introductions of different native provenances into South Africa. Our findings provide important information for ongoing biological control attempts and highlight the importance of resolving taxonomic uncertainties in invasion ecology. 相似文献
37.
In the urodelan amphibian Pleurodeles waltlii, spontaneous anatomical metamorphosis was correlated with an increase in the serum level of thyroxine (T4). It was also accompanied by a change in the myofibrillar ATPase profile of the dorsal skeletal muscle; fibers of larval type were gradually replaced by the adult fiber types I, II A, and II B. Likewise, a myosin isoenzymic transition was observed in dorsal muscle, larval isomyosins were replaced by adult isoforms. In a related species, Ambystoma mexicanum, in which no spontaneous external metamorphosis occurs under standard conditions, the serum T4 level was shown to remain low. During further development, the myofibrillar ATPase profile acquired the adult fiber types, but a high percentage of immature fibers of type II C persisted. Myosin isoenzymic transition was also incomplete; larval isoforms were still distinguished in the neotenic adults. In experimental hypothyroidian P. waltlii, no external metamorphosis occurred; the myofibrillar ATPase profile was of the immature type, and the larval isomyosins persisted. Triiodothyronine induced experimental anatomical metamorphosis in A. mexicanum; only limited changes in the myofibrillar ATPase profile resulted from the treatment, but a complete myosin isoenzymic transition was observed. These results tend to indicate that a moderate increase in the level of thyroid hormone is sufficient to induce the differentiation of adult fiber types, together with the production of adult myosin isoforms in the skeletal dorsal muscle of amphibians, while a pronounced increase would be necessary for repressing the initial larval features. 相似文献
38.
Marta Carboni Tamara Münkemüller Laure Gallien Sébastien Lavergne Alicia Acosta Wilfried Thuiller 《Ecography》2013,36(5):560-568
Darwin proposed two seemingly contradictory hypotheses for a better understanding of biological invasions. Strong relatedness of invaders to native communities as an indication of niche overlap could promote naturalization because of appropriate niche adaptation, but could also hamper naturalization because of negative interactions with native species (‘Darwin's naturalization hypothesis’). Although these hypotheses provide clear and opposing predictions for expected patterns of species relatedness in invaded communities, so far no study has been able to clearly disentangle the underlying mechanisms. We hypothesize that conflicting past results are mainly due to the neglected role of spatial resolution of the community sampling. In this study, we corroborate both of Darwin's expectations by using phylogenetic relatedness as a measure of niche overlap and by testing the effects of sampling resolution in highly invaded coastal plant communities. At spatial resolutions fine enough to detect signatures of biotic interactions, we find that most invaders are less related to their nearest relative in invaded plant communities than expected by chance (phylogenetic overdispersion). Yet at coarser spatial resolutions, native assemblages become more invasible for closely‐related species as a consequence of habitat filtering (phylogenetic clustering). Recognition of the importance of the spatial resolution at which communities are studied allows apparently contrasting theoretical and empirical results to be reconciled. Our study opens new perspectives on how to better detect, differentiate and understand the impact of negative biotic interactions and habitat filtering on the ability of invaders to establish in native communities. 相似文献
39.
Isabel Cabra-Rivas Asunción Saldaña Pilar Castro-Díez Laure Gallien 《Biological invasions》2016,18(2):411-426
Climate, land use and disturbances are well known drivers of invasion. However, their relative influence may change across spatial scales, where climate is expected to be the main filter at broad scales; land use is expected to have more influence at intermediate scales, and disturbance, at fine ones. Understanding the underlying processes that drive invasion patterns at different spatial scales is thus crucial to be able to anticipate the future spread of invaders. Here, we quantified the relative importance of climate, land use, and disturbance on the distribution of the invasive trees Ailanthus altissima and Robinia pseudoacacia, across three nested spatial scales, namely global, country (Spain) and riverbank (three riparian riverbanks). To do so, for each species and scale, we built ensemble species distribution models. We also identified their range filling and inferred the most suitable areas in Spain for them to spread. In general, our study confirms that climate acts as an initial coarse filter of species distribution, whilst both climate and land use were important at the country scale; at the riverbank scale human-mediated disturbances gained importance. However, R. pseudoacacia and A. altissima showed differences in their degree of range filling, where A. altissima has a higher potential for range expansion in the near future. Overall, the integration of different scales into invasion studies shows a great potential to enrich our understanding of species-habitat relationships, and to help anticipate their future dynamics. 相似文献
40.
Hendrik F��hrs Christof Behrens S��bastien Gallien Dimitri Heintz Alain Van Dorsselaer Hans-Peter Braun Walter J. Horst 《Annals of botany》2010,105(7):1129-1140