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941.
942.
Lorenzo Prendini Oscar F. Francke Valerio Vignoli 《Cladistics : the international journal of the Willi Hennig Society》2010,26(2):117-142
The scorpion family Typhlochactidae Mitchell, 1971 is endemic to eastern Mexico and exclusively troglomorphic. Six of the nine species in the family are hypogean (troglobitic), morphologically specialized for life in the cave environment, whereas three are endogean (humicolous) and comparably less specialized. The family therefore provides a model for testing the hypotheses that ecological specialists (stenotopes) evolve from generalist ancestors (eurytopes) and that specialization (in this case to the cavernicolous habitat) is an irreversible, evolutionary dead‐end that ultimately leads to extinction. Due to their cryptic ecology, inaccessible habitat, and apparently low population density, Typhlochactidae are very poorly known. The monophyly of these troglomorphic scorpions has never been rigorously tested, nor has their phylogeny been investigated in a quantitative analysis. We test and confirm their monophyly with a cladistic analysis of 195 morphological characters (142 phylogenetically informative), the first for a group of scorpions in which primary homology of pedipalp trichobothria was determined strictly according to topographical identity (the “placeholder approach”). The phylogeny of Typhlochactidae challenges the conventional wisdom that ecological specialization (stenotopy) is unidirectional and irreversible, falsifying Cope’s Law of the unspecialized and Dollo’s Law of evolutionary irreversibility. Troglobitism is not an evolutionary dead‐end: endogean scorpions evolved from hypogean ancestors on more than one occasion. © The Willi Hennig Society 2009. 相似文献
943.
944.
The formation of an inclusion complex between γ-cyclodextrin and Ln DOTA has been reported in the literature. All Ln DOTA complexes in solution give rise to a network of equilibria between different stereoisomers, which are pairs of enantiomers. By means of near infrared circular dichroism of the Yb derivative, we demonstrate that upon the formation of the host-guest complex, there is a complete stereoselection and that only the Λ(δδδδ) binds. 相似文献
945.
Hybrids of willow (Salix spp.) are today grown as biomass crops for energy in several cool-temperate regions including Sweden. These trees have great
growth potential also under warmer climates, but may suffer from drought and heat. Research on tree growth under drought has
often focused on the responses to permanent water stress. Less attention has been paid to the effects of temporary water stress
on tree growth, although periods of strong water shortage are recurrent in many regions of the world. We performed a greenhouse
experiment to assess the impact of five treatments including permanent (PWS; 30 days of water shortage) and temporary (TWS;
4–12 days of water shortage followed by normal watering) water stress on growth and leaf traits of 15 Salix genotypes. Plant biomass and height increment decreased across treatments in the order control (well-watered) > TWS > PWS,
but there was also a significant genotype × treatment interaction. The pattern in growth traits was not directly reflected
by the leaf traits, for which there was no significant genotype × treatment interaction (except for leaf angle). The significant
genotype × treatment interactions for growth traits indicate a potential for breeding. Permanent water shortage does not necessarily
represent an appropriate environment for the selection of genotypes for environments characterised by temporary water stress. 相似文献
946.
Trine Glad Vibeke Fam Kristiansen Kaare M. Nielsen Lorenzo Brusetti André-Denis G. Wright Monica A. Sundset 《Microbial ecology》2010,60(2):320-330
Dominant colonic bacteria in wild hooded (n = 9), harbour (n = 1) and grey (n = 1) seals were identified using 16S rRNA gene clone libraries (313 clones), revealing 52.7% Bacteroidetes, 41.5% Firmicutes, 4.5% Proteobacteria and 1.0% Fusobacteria. Thirty (77%) of the 39 phylotypes identified were novel, showing <97% sequence similarity to their nearest cultivated relatives.
Mean colonic bacterial cell density, determined by real-time PCR, was high (12.8 log10 cells/g wet wt) for the hooded seals, while the number of methanogenic Archea was low (4.0 log10 cells/g wet wt). The level of ampicillin (ampr) and tetracycline-resistant (tetr) isolates was investigated by cultivation. Aerobic ampr isolates were only detected in colon contents from four hooded seals, whereas aerobic tetr isolates were found in seven of the nine hooded seals. These data provide novel insight to the gut microbiota of Arctic and
sub-Arctic seals living in the wild. 相似文献
947.
948.
Sara Borin Stefano Ventura Fulvia Tambone Francesca Mapelli Florence Schubotz Lorenzo Brusetti Barbara Scaglia Luigi P. D'Acqui Bjørn Solheim Silvia Turicchia Ramona Marasco Kai‐Uwe Hinrichs Franco Baldi Fabrizio Adani Daniele Daffonchio 《Environmental microbiology》2010,12(2):293-303
During primary colonization of rock substrates by plants, mineral weathering is strongly accelerated under plant roots, but little is known on how it affects soil ecosystem development before plant establishment. Here we show that rock mineral weathering mediated by chemolithoautotrophic bacteria is associated to plant community formation in sites recently released by permanent glacier ice cover in the Midtre Lovénbreen glacier moraine (78°53′N), Svalbard. Increased soil fertility fosters growth of prokaryotes and plants at the boundary between sites of intense bacterial mediated chemolithotrophic iron‐sulfur oxidation and pH decrease, and the common moraine substrate where carbon and nitrogen are fixed by cyanobacteria. Microbial iron oxidizing activity determines acidity and corresponding fertility gradients, where water retention, cation exchange capacity and nutrient availability are increased. This fertilization is enabled by abundant mineral nutrients and reduced forms of iron and sulfur in pyrite minerals within a conglomerate type of moraine rock. Such an interaction between microorganisms and moraine minerals determines a peculiar, not yet described model for soil genesis and plant ecosystem formation with potential past and present analogues in other harsh environments with similar geochemical settings. 相似文献
949.
Shannon Kidd Lisa Caldwell Martin Dietrich Ismael Samudio Erika L Spaeth Keri Watson Yuexi Shi James Abbruzzese Marina Konopleva Michael Andreeff Frank C Marini 《Cytotherapy》2010,12(5):615-625
Background aimsBecause of the inflammatory nature and extensive stromal compartment in pancreatic tumors, we investigated the role of mesenchymal stromal cells (MSC) to engraft selectively in pancreatic carcinomas and serve as anti-tumor drug delivery vehicles to control pancreatic cancer progression.MethodsHuman pancreatic carcinoma cells, PANC-1, expressing renilla luciferase were orthotopically implanted into SCID mice and allowed to develop for 10 days. Firefly luciferase-transduced MSC or MSC expressing interferon (IFN)-β were then injected intraperitoneally weekly for 3 weeks. Mice were monitored by bioluminescent imaging for expression of renilla (PANC-1) and firefly (MSC) luciferase.ResultsMSC selectively homed to sites of primary and metastatic pancreatic tumors and inhibited tumor growth (P = 0.032). The production of IFN-β within the tumor site by MSC–IFN-β further suppressed tumor growth (P = 0.0000083). Prior studies indicated that MSC home to sites of inflammation; therefore, we sought to alter the tumor microenvironment through treatment with a potent anti-inflammatory agent. After treatment, inflammation-associated mediators were effectively down-regulated, including NFκB, vascular endothelial growth factor (VEGF) and interleukin (IL)-6 as well as chemokines involved in MSC migration (CCL3 and CCL25). Treatment with the anti-inflammatory agent CDDO-Me before and after MSC–IFN-β injections resulted in reduction of MSC in the tumors and reversed the positive effect of tumor inhibition by MSC–IFN-β alone (P = 0.041).ConclusionsThese results suggest that MSC exhibit innate anti-tumor effects against PANC-1 cells and can serve as delivery vehicles for IFN-β for the treatment of pancreatic cancer. However, these beneficial effects may be lost in therapies combining MSC with anti-inflammatory agents. 相似文献
950.
Gabino Ríos Miguel A Naranjo María-Jesús Rodrigo Enriqueta Alós Lorenzo Zacarías Manuel Cercós Manuel Talón 《BMC plant biology》2010,10(1):276