共查询到20条相似文献,搜索用时 484 毫秒
1.
A. V. Bryanskaya A. A. Berezhnoy A. S. Rozanov S. E. Peltek A. K. Pavlov 《Paleontological Journal》2013,47(9):1089-1092
Adaptive capacity of bacteria and archaea from salt lakes of the Altai Region are discussed. It is established that halophilic archaea (genus Halorubrum) and halotolerant bacteria (genus Halomonas) grow in a wide range of pH and mineralization (in the presence of Cl?, SO 4 2? , ClO 4 ? , Mg2+) and survive at low temperatures with a minor decrease in viability. 相似文献
2.
Background
Archaea share fundamental properties with bacteria and eukaryotes. Yet, they also possess unique attributes, which largely remain poorly characterized. Haloferax volcanii is an aerobic, moderately halophilic archaeon that can be grown in defined media. It serves as an excellent archaeal model organism to study the molecular mechanisms of biological processes and cellular responses to changes in the environment. Studies on haloarchaea have been impeded by the lack of efficient genetic screens that would facilitate the identification of protein functions and respective metabolic pathways.Results
Here, we devised an insertion mutagenesis strategy that combined Mu in vitro DNA transposition and homologous-recombination-based gene targeting in H. volcanii. We generated an insertion mutant library, in which the clones contained a single genomic insertion. From the library, we isolated pigmentation-defective and auxotrophic mutants, and the respective insertions pinpointed a number of genes previously known to be involved in carotenoid and amino acid biosynthesis pathways, thus validating the performance of the methodologies used. We also identified mutants that had a transposon insertion in a gene encoding a protein of unknown or putative function, demonstrating that novel roles for non-annotated genes could be assigned.Conclusions
We have generated, for the first time, a random genomic insertion mutant library for a halophilic archaeon and used it for efficient gene discovery. The library will facilitate the identification of non-essential genes behind any specific biochemical pathway. It represents a significant step towards achieving a more complete understanding of the unique characteristics of halophilic archaea.3.
Aims
Rice fields are an important source for the greenhouse gas methane. Plants play an essential role in carbon supply for soil microbiota, but the influence of the microbial community on carbon cycling is not well understood.Methods
Microcosms were prepared using sand-vermiculite amended with different soils and sediments, and planted with rice. The microcosms at different growth stages were pulse-labeled with 13CO2 followed by tracing 13C in plant, soil and atmospheric carbon pools and quantifying the abundance of methanogenic archaea in rhizosphere soil.Results
Overall,?>85 % of the freshly assimilated carbon was allocated in aboveground plant biomass, approximately 10 % was translocated into the roots and?2 % was recovered in soil organic matter, independently from soil type. Only about 0.3 % was transformed to CH4, but emission of 13C-labeled CH4 started immediately and 13C enrichment revealed that plant-derived carbon was an important source for methanogenesis. The results further demonstrated that carbon assimilation and translocation processes, microbial abundance and gas emission were not only affected by the plant growth stage, but also by the content and type of soil in which the rice plants grew.Conclusions
The study illustrates the close ties between plant physiology, soil properties and microbial communities for carbon turnover and ecosystem functioning. 相似文献4.
Mary LaLonde Hilde Janssens Suyong Yun Juan Crosby Olga Redina Virginie Olive Yelena M Altshuller Seok-Yong Choi Guangwei Du Peter J Gergen Michael A Frohman 《BMC developmental biology》2006,6(1):1-13
Background
Cellularization of the Drosophila embryo is an unusually synchronous form of cytokinesis in which polarized membrane extension proceeds in part through incorporation of new membrane via fusion of apically-translocated Golgi-derived vesicles.Results
We describe here involvement of the signaling enzyme Phospholipase D (Pld) in regulation of this developmental step. Functional analysis using gene targeting revealed that cellularization is hindered by the loss of Pld, resulting frequently in early embryonic developmental arrest. Mechanistically, chronic Pld deficiency causes abnormal Golgi structure and secretory vesicle trafficking.Conclusion
Our results suggest that Pld functions to promote trafficking of Golgi-derived fusion-competent vesicles during cellularization. 相似文献5.
Background
Previous studies indicated that recombinant gas vesicles (r-GV) from a mutant strain of Halobacterium sp. NRC-1 could express a cassette containing test sequences of SIVmac gag derived DNA, and function as an antigen display/delivery system. Tests using mice indicated that the humoral immune response to the gag encoded sequences evoked immunologic memory in the absence of an exogenous adjuvant.Results
The goal of this research was to extend this demonstration to diverse gene sequences by testing recombinant gas vesicles displaying peptides encoded by different SIV genes (SIV tat, rev or nef ). Verification that different peptides can be successfully incorporated into the GvpC surface protein of gas vesicle would support a more general biotechnology application of this potential display/delivery system. Selected SIVsm-GvpC fusion peptides were generated by creating and expressing fusion genes, then assessing the resulting recombinant gas vesicles for SIV peptide specific antigenic and immunogenic capabilities. Results from these analyses support three conclusions: (i) Different recombinant gvpC-SIV genes will support the biosynthesis of chimeric, GvpC fusion proteins which are incorporated into the gas vesicles and generate functional organelles. (ii) Monkey antibody elicited by in vivo infection with SHIV recognizes these expressed SIV sequences in the fusion proteins encoded by the gvpC-SIV fusion genes as SIV peptides. (iii) Test of antiserum elicited by immunizing mice with recombinant gas vesicles demonstrated notable and long term antibody titers. The observed level of humoral responses, and the maintenance of elevated responses to, Tat, Rev and Nef1 encoded peptides carried by the respective r-GV, are consistent with the suggestion that in vivo there may be a natural and slow release of epitope over time.Conclusion
The findings therefore suggest that in addition to providing information about these specific inserts, r-GV displaying peptide inserts from other relevant pathogens could have significant biotechnological potential for display and delivery, or serve as a cost effective initial screen of pathogen derived peptides naturally expressed during infections in vivo. 相似文献6.
Dirk Rothenstein Johannes Baier Thomas D Schreiber Vera Barucha Joachim Bill 《Aquatic biosystems》2012,8(1):1-13
Background
The salt tolerance of halophilic bacteria make them promising candidates for technical applications, like isolation of salt tolerant enzymes or remediation of contaminated saline soils and waters. Furthermore, some halophilic bacteria synthesize inorganic solids resulting in organic–inorganic hybrids. This process is known as biomineralization, which is induced and/or controlled by the organism. The adaption of the soft and eco-friendly reaction conditions of this formation process to technical syntheses of inorganic nano materials is desirable. In addition, environmental contaminations can be entrapped in biomineralization products which facilitate the subsequent removal from waste waters. The moderately halophilic bacteria Halomonas halophila mineralize calcium carbonate in the calcite polymorph. The biomineralization process was investigated in the presence of zinc ions as a toxic model contaminant. In particular, the time course of the mineralization process and the influence of zinc on the mineralized inorganic materials have been focused in this study.Results
H. halophila can adapt to zinc contaminated medium, maintaining the ability for biomineralization of calcium carbonate. Adapted cultures show only a low influence of zinc on the growth rate. In the time course of cultivation, zinc ions accumulated on the bacterial surface while the medium depleted in the zinc contamination. Intracellular zinc concentrations were below the detection limit, suggesting that zinc was mainly bound extracellular. Zinc ions influence the biomineralization process. In the presence of zinc, the polymorphs monohydrocalcite and vaterite were mineralized, instead of calcite which is synthesized in zinc-free medium.Conclusions
We have demonstrated that the bacterial mineralization process can be influenced by zinc ions resulting in the modification of the synthesized calcium carbonate polymorph. In addition, the shape of the mineralized inorganic material is chancing through the presence of zinc ions. Furthermore, the moderately halophilic bacterium H. halophila can be applied for the decontamination of zinc from aqueous solutions. 相似文献7.
8.
Jan Čermák Pavel Cudlín Roman Gebauer Isabella Børja Milena Martinková Zdeněk Stanĕk Jan Koller Jindřich Neruda Nadezhda Nadezhdina 《Plant and Soil》2013,372(1-2):401-415
Aims
Estimates of root absorption magnitude are needed for the balanced management of forest ecosystems, but no methods able to work on the whole tree and stand level were available. Modified earth impedance method was developed recently and here it was tested, by comparing the results with those obtained by combination of several classical methods.Methods
We used direct (soil cores, scanning and microscopy) and indirect (sap flow patterns and modified earth impedance) methods in an attempt to estimate the absorptive root area indexes (RAI) at two sites of about 25 and 40-years-old Norway spruce. We considered the geometric surfaces of all scanned fine roots to be equal to the fine root absorptive area (RAI scan ). To estimate the potentially physically permeable area of fine roots, we microscopically evaluated the point of secondary xylem appearance and calculated the geometric area of root portions with primary structure (RAI micro ). We termed the area of electrically conductive root surface as the active (ion) absorptive area (RAI mei ) and measured its extent by the modified earth impedance (MEI) method.Results
The highest values for absorptive root areas at the two experimental sites we obtained with the scanning method (RAI scan was considered to be 100%), followed by the RAI micro (51%) and RAI mei (32%). RAImei reached about 2/3 of RAImicro. The surface area of the ectomycorrhizal hyphae was an order of magnitude larger than that of all fine roots, but the MEI did not measure such increase.Conclusions
We showed that the absorptive root area, indirectly estimated by the MEI, provides consistent results that approach the values obtained for fine roots with a primary structure estimated by traditional direct methods. The similar range of the values for the absorptive root surface area obtained by microscopy and by the MEI method indicates that this method is feasible and that it could be used to determine the extent of active absorptive root surface areas in forests. 相似文献9.
Pierfrancesco Nardi Masako Akutsu Juan Pariasca-Tanaka Matthias Wissuwa 《Plant and Soil》2013,367(1-2):627-637
Aims
It has been reported that root exudates of Sorghum bicolor can inhibit nitrification in a bioassay using Nitrosomonas, and methyl 3-(4-hydroxyphenyl) propionate (MHPP) was identified as one of the nitrification inhibiting compounds. Therefore, we have investigated the effects of this compound on nitrogen dynamic, potential nitrification activity and on soil microorganisms.Methods
We conducted soil incubation experiments using synthetic MHPP to evaluate its effect on changes in inorganic soil nitrogen pools, on nitrification activity and on abundance of ammonia-oxidizing bacteria and archaea. Addition of MHPP at two concentrations equivalent to 70 and 350 μg C g?1 soil was compared to glucose as a carbon source and to the commercially available nitrification inhibitor dicyandiamide (DCD).Results
Soil amended with the high dose of MHPP and with DCD showed reduced nitrate content and low nitrification activity after 3 and 7 days of incubation. This was mirrored by a 70 % reduction in potential nitrification activity compared to a nitrogen-only control. None of the incubation treatments affected non-target microbial counts as estimated by 16S rRNA gene copy numbers, however, the high dose of MHPP significantly reduced the abundance of ammonia-oxidizing bacteria and archaea.Conclusions
These findings suggest that MHPP is capable of suppressing nitrification in soil, possibly by reducing the population size and activity of ammonia-oxidizing microorganisms. 相似文献10.
Background
Signaling studies in cell lines are hampered by non-physiological alterations obtained in vitro. Physiologic primary tumor cells from patients with leukemia require passaging through immune-compromised mice for amplification. The aim was to enable molecular work in patients' ALL cells by establishing siRNA transfection into cells amplified in mice.Results
We established delivering siRNA into these cells without affecting cell viability. Knockdown of single or multiple genes reduced constitutive or induced protein expression accompanied by marked signaling alterations.Conclusion
Our novel technique allows using patient-derived tumor cells instead of cell lines for signaling studies in leukemia. 相似文献11.
12.
Aruna Govindaraju Alper Uzun LaShonda Robertson Mehmet O Atli Abdullah Kaya Einko Topper Elizabeth A Crate James Padbury Andy Perkins Erdogan Memili 《Reproductive biology and endocrinology : RB&E》2012,10(1):1-10
Background
Degenerative effects of critical regulators of reproduction, the kisspeptin peptides, on cellular aspects of sexually immature male gonads are known but similar information on accessory sex glands remain elusive.Methods
Prepubertal laboratory rats were injected kisspeptin-10 at three different dosage concentrations (10 pg, 1 ng and 1 microgram) for a period of continuous 12 days at the rate of two doses per day. Control rats were maintained in parallel. The day following the end of the experimental period, seminal vesicles were removed and processed for light and electron microscopic examination using the standard methods. DNA damage was estimated by DNA ladder assay and DNA fragmentation assay.Results
The results demonstrated cellular degeneration. Epithelial cell height of seminal vesicles decreased significantly at all doses (P < 0.05). Marked decrease in epithelial folds was readily noticeable, while the lumen was dilated. Ultrastructural changes were characterized by dilatation of endoplasmic reticulum and Golgi complex, heterochromatization of nuclei, invagination of nuclear membranes and a decreased number of secretory granules. Percent DNA damage to the seminal vesicle was 19.54 +/- 1.98, 38.06 +/- 2.09 and 58.18 +/- 2.59 at 10 pg, 1 ng and 1 microgram doses respectively.Conclusion
The study reveals that continuous administration of kisspeptin does not lead to an early maturation but instead severe degeneration of sexually immature seminal vesicles. 相似文献13.
14.
Purpose
to determine diagnosis and prognosis value of MRI in Peyronie’s disease.Material and Methods
thirty one penile MR examinations have been performed in 28 patients aged between 21 and 73. (1 tesla; surface coil; sagittal SET1, axial SET2 weighted, T1 before and after Gadolinium)Results
Conclusion
MRI can be helpfull in the pretreatment assessment and int he follow-up of Peyronie’s disease. 相似文献15.
16.
17.
18.
Background
The availability of sequences from whole genomes to reconstruct the tree of life has the potential to enable the development of phylogenomic hypotheses in ways that have not been before possible. A significant bottleneck in the analysis of genomic-scale views of the tree of life is the time required for manual curation of genomic data into multi-gene phylogenetic matrices.Results
To keep pace with the exponentially growing volume of molecular data in the genomic era, we have developed an automated technique, ASAP (Automated Simultaneous Analysis Phylogenetics), to assemble these multigene/multi species matrices and to evaluate the significance of individual genes within the context of a given phylogenetic hypothesis.Conclusion
Applications of ASAP may enable scientists to re-evaluate species relationships and to develop new phylogenomic hypotheses based on genome-scale data. 相似文献19.
Bashar A. Zeidan Ramsey I. Cutress Claire Hastie Alex H. Mirnezami Graham Packham Paul A. Townsend 《Clinical proteomics》2009,5(3-4):133-147