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201.
Zuccolo A Bowers JE Estill JC Xiong Z Luo M Sebastian A Goicoechea JL Collura K Yu Y Jiao Y Duarte J Tang H Ayyampalayam S Rounsley S Kudrna D Paterson AH Pires JC Chanderbali A Soltis DE Chamala S Barbazuk B Soltis PS Albert VA Ma H Mandoli D Banks J Carlson JE Tomkins J dePamphilis CW Wing RA Leebens-Mack J 《Genome biology》2011,12(5):R48-14
Background
Recent phylogenetic analyses have identified Amborella trichopoda, an understory tree species endemic to the forests of New Caledonia, as sister to a clade including all other known flowering plant species. The Amborella genome is a unique reference for understanding the evolution of angiosperm genomes because it can serve as an outgroup to root comparative analyses. A physical map, BAC end sequences and sample shotgun sequences provide a first view of the 870 Mbp Amborella genome.Results
Analysis of Amborella BAC ends sequenced from each contig suggests that the density of long terminal repeat retrotransposons is negatively correlated with that of protein coding genes. Syntenic, presumably ancestral, gene blocks were identified in comparisons of the Amborella BAC contigs and the sequenced Arabidopsis thaliana, Populus trichocarpa, Vitis vinifera and Oryza sativa genomes. Parsimony mapping of the loss of synteny corroborates previous analyses suggesting that the rate of structural change has been more rapid on lineages leading to Arabidopsis and Oryza compared with lineages leading to Populus and Vitis. The gamma paleohexiploidy event identified in the Arabidopsis, Populus and Vitis genomes is shown to have occurred after the divergence of all other known angiosperms from the lineage leading to Amborella.Conclusions
When placed in the context of a physical map, BAC end sequences representing just 5.4% of the Amborella genome have facilitated reconstruction of gene blocks that existed in the last common ancestor of all flowering plants. The Amborella genome is an invaluable reference for inferences concerning the ancestral angiosperm and subsequent genome evolution. 相似文献202.
Denise Knobloch Andre Clemens Kai Ostermann Gerhard Rödel 《Engineering in Life Science》2011,11(5):458-462
In the present study, we demonstrate that the Escherichia coli–Bacillus megaterium shuttle vector pHIS1522 can be used as a versatile expression vector. Recombinant genes under the control of the xylA promoter are constitutively expressed at a high level in E. coli strains, whereas their expression is strongly induced by the addition of xylose in B. megaterium. The utilization of D ‐xylose is known to be dependent on the xylAB genes in a number of bacteria. For B. megaterium a XylA‐based expression system was established that allows tightly regulated and highly efficient heterologous gene expression. The open reading frame (ORF) of the fluorescent protein turboRFP was cloned under the control of the xylA promoter of B. megaterium in the shuttle vector pHIS1522. Unexpectedly, tRFP expression was not only observed in B. megaterium, but also in E. coli. Based on fluorescence measurements and Western blot analysis, expression was comparable or slightly higher compared with the commonly used pET vectors. Therefore, pHIS1522 can be used as a versatile expression vector in both, B. megaterium and E. coli. 相似文献
203.
de Almeida LA Carvalho NB Oliveira FS Lacerda TL Vasconcelos AC Nogueira L Bafica A Silva AM Oliveira SC 《PloS one》2011,6(8):e23135
Type I interferons (IFNs) are cytokines that orchestrate diverse immune responses to viral and bacterial infections. Although typically considered to be most important molecules in response to viruses, type I IFNs are also induced by most, if not all, bacterial pathogens. In this study, we addressed the role of type I IFN signaling during Brucella abortus infection, a facultative intracellular bacterial pathogen that causes abortion in domestic animals and undulant fever in humans. Herein, we have shown that B. abortus induced IFN-β in macrophages and splenocytes. Further, IFN-β induction by Brucella was mediated by IRF3 signaling pathway and activates IFN-stimulated genes via STAT1 phosphorylation. In addition, IFN-β expression induced by Brucella is independent of TLRs and TRIF signaling but MyD88-dependent, a pathway not yet described for Gram-negative bacteria. Furthermore, we have identified Brucella DNA as the major bacterial component to induce IFN-β and our study revealed that this molecule operates through a mechanism dependent on RNA polymerase III to be sensed probably by an unknown receptor via the adaptor molecule STING. Finally, we have demonstrated that IFN-αβR KO mice are more resistant to infection suggesting that type I IFN signaling is detrimental to host control of Brucella. This resistance phenotype is accompanied by increased IFN-γ and NO production by IFN-αβR KO spleen cells and reduced apoptosis. 相似文献
204.
Ammonia-oxidizing archaea (AOA) outnumber ammonia-oxidizing bacteria (AOB) in many terrestrial and aquatic environments. Although nitrification is the primary function of aquarium biofilters, very few studies have investigated the microorganisms responsible for this process in aquaria. This study used quantitative real-time PCR (qPCR) to quantify the ammonia monooxygenase (amoA) and 16S rRNA genes of Bacteria and Thaumarchaeota in freshwater aquarium biofilters, in addition to assessing the diversity of AOA amoA genes by denaturing gradient gel electrophoresis (DGGE) and clone libraries. AOA were numerically dominant in 23 of 27 freshwater biofilters, and in 12 of these biofilters AOA contributed all detectable amoA genes. Eight saltwater aquaria and two commercial aquarium nitrifier supplements were included for comparison. Both thaumarchaeal and bacterial amoA genes were detected in all saltwater samples, with AOA genes outnumbering AOB genes in five of eight biofilters. Bacterial amoA genes were abundant in both supplements, but thaumarchaeal amoA and 16S rRNA genes could not be detected. For freshwater aquaria, the proportion of amoA genes from AOA relative to AOB was inversely correlated with ammonium concentration. DGGE of AOA amoA genes revealed variable diversity across samples, with nonmetric multidimensional scaling (NMDS) indicating separation of freshwater and saltwater fingerprints. Composite clone libraries of AOA amoA genes revealed distinct freshwater and saltwater clusters, as well as mixed clusters containing both freshwater and saltwater amoA gene sequences. These results reveal insight into commonplace residential biofilters and suggest that aquarium biofilters may represent valuable biofilm microcosms for future studies of AOA ecology. 相似文献
205.
206.
Riquelme M Yarden O Bartnicki-Garcia S Bowman B Castro-Longoria E Free SJ Fleissner A Freitag M Lew RR Mouriño-Pérez R Plamann M Rasmussen C Richthammer C Roberson RW Sanchez-Leon E Seiler S Watters MK 《Fungal biology》2011,115(6):446-474
Neurospora crassa has been at the forefront of biological research from the early days of biochemical genetics to current progress being made in understanding gene and genetic network function. Here, we discuss recent developments in analysis of the fundamental form of fungal growth, development and proliferation -- the hypha. Understanding the establishment and maintenance of polarity, hyphal elongation, septation, branching and differentiation are at the core of current research. The advances in the identification and functional dissection of regulatory as well as structural components of the hypha provide an expanding basis for elucidation of fundamental attributes of the fungal cell. The availability and continuous development of various molecular and microscopic tools, as utilized by an active and co-supportive research community, promises to yield additional important new discoveries on the biology of fungi. 相似文献
207.
Quantification of optic disc edema during exposure to high altitude shows no correlation to acute mountain sickness 总被引:1,自引:0,他引:1
Willmann G Fischer MD Schatz A Schommer K Messias A Zrenner E Bartz-Schmidt KU Gekeler F 《PloS one》2011,6(11):e27022
Background
The study aimed to quantify changes of the optic nerve head (ONH) during exposure to high altitude and to assess a correlation with acute mountain sickness (AMS). This work is related to the Tuebingen High Altitude Ophthalmology (THAO) study.Methodology/Principal Findings
A confocal scanning laser ophthalmoscope (cSLO, Heidelberg Retina Tomograph, HRT3®) was used to quantify changes at the ONH in 18 healthy participants before, during and after rapid ascent to high altitude (4559 m). Slitlamp biomicroscopy was used for clinical optic disc evaluation; AMS was assessed with Lake Louise (LL) and AMS-cerebral (AMS-c) scores; oxygen saturation (SpO2) and heart rate (HR) were monitored. These parameters were used to correlate with changes at the ONH. After the first night spent at high altitude, incidence of AMS was 55% and presence of clinical optic disc edema (ODE) 79%. Key stereometric parameters of the HRT3® used to describe ODE (mean retinal nerve fiber layer [RNFL] thickness, RNFL cross sectional area, optic disc rim volume and maximum contour elevation) changed significantly at high altitude compared to baseline (p<0.05) and were consistent with clinically described ODE. All changes were reversible in all participants after descent. There was no significant correlation between parameters of ODE and AMS, SpO2 or HR.Conclusions/Significance
Exposure to high altitude leads to reversible ODE in the majority of healthy subjects. However, these changes did not correlate with AMS or basic physiologic parameters such as SpO2 and HR. For the first time, a quantitative approach has been used to assess these changes during acute, non-acclimatized high altitude exposure. In conclusion, ODE presents a reaction of the body to high altitude exposure unrelated to AMS. 相似文献208.
Kiani A Nielsen MO Tauson AH Tygesen MP Husted SM Chwalibog A 《Archives of animal nutrition》2011,65(1):46-54
The objective of this study was to investigate the effects of foetal undernutrition on the metabolism in growing lambs. Seven-month-old lambs whose mothers had been fed either restrictively (RN; n = 14) or adequately (AN; n = 6) in late gestation were fasted for three days. One hour before fasting and after 48 h and 72 h fasting, changes in plasma concentrations of metabolites, i.e. glucose, nonesterified fatty acids (NEFA), 3-beta-hydroxybutyrate (BOHB) and urea as well as hormones, i.e. insulin, the insulin-like growth factor (IGF-I) and leptin, were determined. Blood glucose, NEFA, urea, insulin, IGF-I and leptin were not different between the two groups of lambs. Unexpectedly, at the end of the 3 d fasting, in spite of lower NEFA concentration (1.6 +/- 0.03 vs. 1.9 +/- 0.05 mM in Groups RN and AN, respectively), the BOHB concentration in RN lambs (0.94 +/- 0.02 mM) was significantly higher than that in AN lambs (0.78 +/- 0.04 mM). This higher rate of BOHB production might be interpreted as perturbations in ketone body metabolism potentially induced by undernutrition during foetal life. However, more investigations are necessary to clarify this interrelationship. 相似文献
209.
Wu HY Quintana FJ da Cunha AP Dake BT Koeglsperger T Starossom SC Weiner HL 《PloS one》2011,6(8):e23618
210.