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11.
Abundances and potential activities of nitrogen cycling microbial communities along a chronosequence of a glacier forefield 总被引:1,自引:0,他引:1
Robert Brankatschk Stefanie T?we Kristina Kleineidam Michael Schloter Josef Zeyer 《The ISME journal》2011,5(6):1025-1037
Glacier forefields are ideal ecosystems to study the development of nutrient cycles as well as single turnover processes during soil development. In this study, we examined the ecology of the microbial nitrogen (N) cycle in bulk soil samples from a chronosequence of the Damma glacier, Switzerland. Major processes of the N cycle were reconstructed on the genetic as well as the potential enzyme activity level at sites of the chronosequence that have been ice-free for 10, 50, 70, 120 and 2000 years. In our study, we focused on N fixation, mineralization (chitinolysis and proteolysis), nitrification and denitrification. Our results suggest that mineralization, mainly the decomposition of deposited organic material, was the main driver for N turnover in initial soils, that is, ice-free for 10 years. Transient soils being ice-free for 50 and 70 years were characterized by a high abundance of N fixing microorganisms. In developed soils, ice-free for 120 and 2000 years, significant rates of nitrification and denitrification were measured. Surprisingly, copy numbers of the respective functional genes encoding the corresponding enzymes were already high in the initial phase of soil development. This clearly indicates that the genetic potential is not the driver for certain functional traits in the initial phase of soil formation but rather a well-balanced expression of the respective genes coding for selected functions. 相似文献
12.
Markus Ruchty Roberto Romani Linda S. Kuebler Sara Ruschioni Flavio Roces Nunzio Isidoro Christoph J. Kleineidam 《Arthropod Structure & Development》2009,38(3):195-205
Social insects show a variety of temperature-guided behaviors. Depending on whether heat reaches the sensillum via air movements (convective heat) or as radiant heat, specific adaptations of thermo-sensitive sensilla are expected. In the present study the morphology and the physiology of thermo-sensitive peg-in-pit sensilla (S. coeloconica) of the leaf-cutting ant Atta vollenweideri were investigated. S. coeloconica are located predominantly in a single cluster on the apical antennomere, and connect to the outside through a small aperture. The sensory peg is double-walled, embedded in a chamber and innervated by three unbranched dendrites. Using tungsten electrodes, activity of the sensory neurons was measured. In most cases, the neuron with the largest spike amplitude responds to changes in air temperature (convective heat) as well as to radiant heat. In response to a drop in air temperature, the neuron shows a phasic-tonic response followed by a complete adaptation within 1 min (cold-sensitive neuron). Based on their morphology and physiology, it is suggested that the S. coeloconica are involved in the recently described thermal orientation behavior of A. vollenweideri leaf-cutting ants. 相似文献
13.
van Gool CJ van Houwelingen AC Hornstra G 《The Journal of nutritional biochemistry》2000,11(11-12):543-547
Phenylketonuric patients are on a special diet that lacks certain essential fatty acids. This study evaluates the essential fatty acid status of a group of phenylketonuric patients in the Netherlands undergoing dietary treatment. To this end, the essential fatty acid status of nine phenylketonuria patients was studied. On the basis of age and gender, two control subjects were selected for each patient. The essential fatty acid composition of duplicate food portions and the essential fatty acid status of plasma and erythrocytes were analyzed. Phenylketonuria subjects had a different essential fatty acid profile from their peers, especially concerning the n-3 fatty acids. N-6 and n-3 fatty long-chain polyenes were hardly consumed by phenylketonuria subjects, in contrast to the control subjects. Linoleic acid, on the other hand, was consumed in significantly higher amounts by phenylketonuria subjects and made up about 40% of their daily fat consumption. The essential fatty acid consumption pattern of the phenylketonuria subjects is mirrored by the essential fatty acid concentrations in blood. The essential fatty acid status of the phenylketonuric diet should be improved in order to prevent deficiency in n-3 fatty acids. 相似文献
14.
Lipoteichoic acid is an important microbe-associated molecular pattern of Lactobacillus rhamnosus GG
Claes Ingmar JJ Segers Marijke E Verhoeven Tine LA Dusselier Michiel Sels Bert F De Keersmaecker Sigrid CJ Vanderleyden Jos Lebeer Sarah 《Microbial cell factories》2012,11(1):1-8
Background
Receptors with a single transmembrane (TM) domain are essential for the signal transduction across the cell membrane. NMR spectroscopy is a powerful tool to study structure of the single TM domain. The expression and purification of a TM domain in Escherichia coli (E.coli) is challenging due to its small molecular weight. Although ketosteroid isomerase (KSI) is a commonly used affinity tag for expression and purification of short peptides, KSI tag needs to be removed with the toxic reagent cyanogen bromide (CNBr).Result
The purification of the TM domain of p75 neurotrophin receptor using a KSI tag with the introduction of a thrombin cleavage site is described herein. The recombinant fusion protein was refolded into micelles and was cleaved with thrombin. Studies showed that purified protein could be used for structural study using NMR spectroscopy.Conclusions
These results provide another strategy for obtaining a single TM domain for structural studies without using toxic chemical digestion or acid to remove the fusion tag. The purified TM domain of p75 neurotrophin receptor will be useful for structural studies. 相似文献15.
Nadine?AME?van der BeekEmail author Juna?M?de Vries Marloes?LC?Hagemans Wim?CJ?Hop Marian?A?Kroos John?HJ?Wokke Marianne?de Visser Baziel?GM?van Engelen Jan?BM?Kuks Anneke?J?van der Kooi Nicolette?C?Notermans Karin?G?Faber Jan?JGM?Verschuuren Arnold?JJ?Reuser Ans?T?van der Ploeg Pieter?A?van Doorn 《Orphanet journal of rare diseases》2012,7(1):88
Background
Due partly to physicians’ unawareness, many adults with Pompe disease are diagnosed with great delay. Besides, it is not well known which factors influence the rate of disease progression, and thus disease outcome. We delineated the specific clinical features of Pompe disease in adults, and mapped out the distribution and severity of muscle weakness, and the sequence of involvement of the individual muscle groups. Furthermore, we defined the natural disease course and identified prognostic factors for disease progression.Methods
We conducted a single-center, prospective, observational study. Muscle strength (manual muscle testing, and hand-held dynamometry), muscle function (quick motor function test), and pulmonary function (forced vital capacity in sitting and supine positions) were assessed every 3–6 months and analyzed using repeated-measures ANOVA.Results
Between October 2004 and August 2009, 94 patients aged between 25 and 75 years were included in the study. Although skeletal muscle weakness was typically distributed in a limb-girdle pattern, many patients had unfamiliar features such as ptosis (23%), bulbar weakness (28%), and scapular winging (33%). During follow-up (average 1.6 years, range 0.5-4.2 years), skeletal muscle strength deteriorated significantly (mean declines of ?1.3% point/year for manual muscle testing and of ?2.6% points/year for hand-held dynamometry; both p<0.001). Longer disease duration (>15 years) and pulmonary involvement (forced vital capacity in sitting position <80%) at study entry predicted faster decline. On average, forced vital capacity in supine position deteriorated by 1.3% points per year (p=0.02). Decline in pulmonary function was consistent across subgroups. Ten percent of patients declined unexpectedly fast.Conclusions
Recognizing patterns of common and less familiar characteristics in adults with Pompe disease facilitates timely diagnosis. Longer disease duration and reduced pulmonary function stand out as predictors of rapid disease progression, and aid in deciding whether to initiate enzyme replacement therapy, or when.16.
The results described in the accompanying article support the model in
which glucosylphosphoryldolichol (Glc-P-Dol) is synthesized on the
cytoplasmic face of the ER, and functions as a glucosyl donor for three
Glc-P-Dol:Glc0-2Man9-GlcNAc2-P-P-Dol glucosyltransferases (GlcTases) in the
lumenal compartment. In this study, the enzymatic synthesis and structural
characterization by NMR and electrospray-ionization tandem mass
spectrometry of a series of water-soluble beta-Glc-P-Dol analogs containing
2-4 isoprene units with either the cis - or trans - stereoconfiguration in
the beta-position are described. The water- soluble analogs were (1) used
to examine the stereospecificity of the Glc-P-Dol:Glc0-2Man9GlcNAc2-P-P-Dol
glucosyltransferases (GlcTases) and (2) tested as potential substrates for
a membrane protein(s) mediating the transbilayer movement of Glc-P-Dol in
sealed ER vesicles from rat liver and pig brain. The Glc-P-Dol-mediated
GlcTases in pig brain microsomes utilized [3H]Glc-labeled Glc-P-Dol10,
Glc-P-(omega, c )Dol15, Glc-P(omega, t,t )Dol20, and Glc-P-(omega, t,c
)Dol20as glucosyl donors with [3H]Glc3Man9GlcNAc2-P-P-Dol the major product
labeled in vitro. A preference was exhibited for C15-20 substrates
containing an internal cis -isoprene unit in the beta-position. In
addition, the water-soluble analog, Glc-P-Dol10, was shown to enter the
lumenal compartment of sealed microsomal vesicles from rat liver and pig
brain via a protein-mediated transport system enriched in the ER. The
properties of the ER transport system have been characterized. Glc-
P-Dol10was not transported into or adsorbed by synthetic PC-liposomes or
bovine erythrocytes. The results of these studies indicate that (1) the
internal cis -isoprene units are important for the utilization of Glc-P-Dol
as a glucosyl donor and (2) the transport of the water- soluble analog may
provide an experimental approach to assay the hypothetical "flippase"
proposed to mediate the transbilayer movement of Glc-P-Dol from the
cytoplasmic face of the ER to the lumenal monolayer.
相似文献
17.
Benzene, toluene, ethylbenzene, and xylene are collectively known as BTEX which contributes to volatile environmental contaminants. This present study investigates the microbial degradation of BTEX in batch and continuous soil column experiments and its effects on soil matric potential. Batch degradation experiments were performed with different initial concentrations of BTEX using the BTEX tolerant culture isolated from petroleum-contaminated soil. In batch study, the degradation pattern for single substrate showed that xylene was degraded much faster than other compounds followed by ethylbenzene, toluene, and benzene with the highest μmax = 0.140 h?1 during initial substrate concentration of 100 mg L?1. Continuous degradation experiments were performed in a soil column with an inlet concentration of BTEX of about 2000 mg L?1 under unsaturated flow in anaerobic condition. BTEX degradation pattern was studied with time and the matric potential of the soil at different parts along the length of the column were determined at the end of the experiment. In continuous degradation study, BTEX compounds were degraded with different degradation pattern and an increase in soil matric potential was observed with an increase in depth from top to bottom in the column with applied suction head. It was found that column biodegradation contributed to 69.5% of BTEX reduction and the bacterial growth increased the soil matric potential of about 34% on an average along the column height. Therefore, this study proves that it is significant to consider soil matric potential in modeling fate and transport of BTEX in unsaturated soils. 相似文献
18.
Background
OMA is a project that aims to identify orthologs within publicly available, complete genomes. With 657 genomes analyzed to date, OMA is one of the largest projects of its kind. 相似文献19.
The sensilla ampullacea on the apical antennomere of the leaf-cutting ant Atta sexdens were investigated regarding both their responses to CO2 and their ultrastructure. By staining the sensillum during recording, we confirmed that the sensilla ampullacea are responsible for CO2 perception. We showed that the sensory neurons of the sensilla ampullacea are continuously active without adaptation during stimulation with CO2 (test duration: 1 h). This feature should enable ants to assess the absolute CO2 concentration inside their nests. Sensilla ampullacea have been found grouped mainly on the dorso-lateral side of the distal antennal segment. Scanning and transmission electron microscopic investigations revealed that the external pore opens into a chamber which connects to the ampulla via a cuticular duct. We propose protection against evaporation as a possible function of the duct. The ampulla houses a peg which is almost as long as the ampulla and shows cuticular ridges on the external wall. The ridges are separated by furrows with cuticular pores. The peg is innervated by only one sensory neuron with a large soma. Its outer dendritic segment is enveloped by a dendritic sheath up to the middle of the peg. From the middle to the tip numerous dendritic branches (up to 100) completely fill the distal half of the peg. This is the first report of a receptor cell with highly branched dendrites and which probably is tuned to CO2 exclusively. 相似文献
20.