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EN
Two species of mosses in relation to nitrogen metabolism were examined. This subject is little known in this group of plant. Investigations of nitrate reductase activity in green tissues of Brachythecium rutabulum (Hedw.) Schimp. and Atrichum undulatum (Hedw.) P.Beauv. were performed. The study was conducted in two localities: heavy contaminated waste tip Skalny located in Upper Silesia, and Blonia City Park in Bielsko-Biala which place was chosen as a control area. For both species high activity of the enzyme was detected. The nitrate reductase activity varied between 99 to 9093 nmol per g dry mass per hour for B. rutabulum and 265 to 5135 nmol per g d.m. per hour of nitrite synthesized for A. undulatum respectively on Skalny waste tip. In the control area the results varied between 747 to 1077 for B. rutabulum and 171 to 518 nmol per g d.m. per hour of nitrite synthesized for A. undulatum, respectively. The differences were statistically significant only between the two species but not between habitats probably due to high dispersion and small amount of replications. The levels of nitrate and nitrite in stream water in both areas were also measured. In the Skalny waste tip there were high and reached 1.66 mg · dm-3 of nitrite and 65 mg · dm-3 of nitrate, respectively. In the control area these amounts were lower and reach zero level for nitrite and 4.5 mg · dm-3 of nitrate, respectively.
PL
Dwa gatunki mchów badano pod kątem asymilacji azotu. To zagadnienie jest mało poznane u tej grupy roślin. Przeprowadzono badania aktywności reduktazy azotanowej w zielonych tkankach Brachythecium rutabulum (Hedw.) Schimp. i Atrichum undulatum (Hedw.) P.Beauv. Badania zostały wykonane w dwóch miejscach: na hałdzie powęglowej Skalny na Górnym Śląsku i w parku w dzielnicy Błonia w Bielsku-Białej, które zostało wybrane jako miejsce kontrolne. Dla obu gatunków stwierdzono wysoką aktywność enzymu. Aktywność reduktazy azotanowej wahała się od 99 do 9093 nmol na g suchej masy na godzinę dla B. rutabulum i 265 do 5135 nmol na g suchej masy na godzinę azotynu syntetyzowanego u A. undulatum na hałdzie Skalny. W miejscu kontrolnym wyniki wahały się od 747 do 1077 dla B. rutabulum i 171 do 518 nmol na g sm/h u A. undulatum. Różnice były statystycznie znaczące tylko pomiędzy gatunkami, ale nie pomiędzy typem siedliska prawdopodobnie ze względu na wysoką dyspersję i małą liczbę powtórzeń. Zmierzono także poziom azotanów i azotynów w strumieniu wody w obu miejscach. Na hałdzie Skalny zawartość była wysoka i osiągnęła odpowiednio: 1,66 mg dm-3 azotynu oraz 65 mg dm-3 azotanu. W miejscu kontrolnym wartości te były niższe i osiągnęły odpowiednio poziom zerowy dla azotynów i 4,5 mg dm-3 dla azotanu.
EN
Two early nodulin 40 (enod40) genes, ENOD40-1, the shortest legume ENOD40 gene, and ENOD40-2, were isolated from Lupinus luteus, a legume with indeterminate nodules. Both genes were expressed at similar levels during symbiosis with nitrogen-fixing bacteria. ENOD40 phylogeny clustered the L. luteus genes with legumes forming determinate nodules and revealed peptide similarities. The ENOD40-1 small ORF A fused to a reporter gene was efficiently expressed in plant cells, indicating that the start codon is recognized for translation. The ENOD40-1 RNA structure predicted based on Pb(II)-induced cleavage and modeling revealed four structurally conserved domains, an absence of domain 4 characteristic for legumes of indeterminate nodules, and interactions between the conserved region I and a region located upstream of domain 6. Domain 2 contains Mg(II) ion binding sites essential for organizing RNA secondary structure. The differences between L. luteus and Glycine max ENOD40 RNA models suggest the possibility of a switch between two structural states of ENOD40 transcript.
EN
A gene for the Δturase specific to stearoyl-ACP (acyl carrier protein) was identified from yellow lupine (Lupinus luteus) cDNA and genomic libraries through the differential display method. The desaturase transcript appears in plants infected with Bradyrhizobium sp. (Lupinus) as revealed by Northern hybridization, RT-PCR and expression of β-glucuronidase under the desaturase promoter. A small amount of desaturase transcript was also detected in uninfected plants, which suggests that the gene does not belong to the strict nodule-specific sequences. The desaturase provides unsaturated fatty acids for additional cell membrane synthesis. During nodule and symbiosome development a peribacteroid membrane is formed and the requirement for membrane surface increases, thus the level of desaturase expression is also higher. Transgenic plants of Nicotiana tabacum with overexpression of the full-length lupine stearoyl-ACP desaturase sequence were obtained. They revealed higher content of unsaturated fatty acids (especially oleic acid) in comparison with control plants.
EN
The fucosyltransferase NodZ is involved in the biosynthesis of the nodulation factor in nitrogen-fixing symbiotic bacteria. It catalyzes α1,6 transfer of l-fucose from GDP-fucose to the reducing residue of the synthesized Nod oligosaccharide. We present the structure of the NodZ protein from Bradyrhizobium expressed in Escherichia coli and crystallized in the presence of phosphate ions in two crystal forms. The enzyme is arranged into two domains of nearly equal size. Although NodZ falls in one broad class (GT-B) with other two-domain glycosyltransferases, the topology of its domains deviates from the canonical Rossmann fold, with particularly high distortions in the N-terminal domain. Mutational data combined with structural and sequence alignments indicate residues of potential importance in GDP-fucose binding or in the catalytic mechanism. They are all clustered in three conserved sequence motifs located in the C-terminal domain.
Kosmos
|
2017
|
vol. 66
|
issue 2
185-192
PL
Azot jest jednym z najważniejszych pierwiastków biogennych. Jest niezbędny do prawidłowego wzrostu i funkcjonowania wszystkich organizmów. Pierwiastek ten występuje w glebie w wielu formach i jest bardzo aktywny. Ulega przemianom z jednych form chemicznych w inne. Mikroorganizmy odgrywają ważną rolę w przemianach azotu. Główne procesy składające się na cykl azotu to: wiązanie, amonifikacja, nitryfikacja i denitryfikacja. Wiązanie azotu atmosferycznego jest ważnym źródłem biologicznie dostępnego azotu w biosferze, amonifikacja to redukcja związków organicznych do amoniaku, nitryfikacja to dwuetapowy proces utleniania amoniaku do azotanów, a denitryfikacja to redukcja azotanów do azotu gazowego. Intensywność mikrobiologicznych procesów w glebie zależy m.in. od typu gleby, wilgotności, natlenienia, roślinności, nawożenia. Odczyn również wywiera wpływ na przemiany azotu w glebie. Większość gatunków mikroorganizmów optymalnie wzrasta w odczynie obojętnym. W kwaśnych glebach aktywność mikroorganizmów i intensywność procesów jest hamowana.
EN
Nitrogen is one of the most important biogenic compounds, indispensable for growth and functioning of all the organisms. This chemical element exist in soil in many forms, some of which are very active. Microorganisms play an important role in the nitrogen cycle. Main processes involved in the nitrogen cycle consists of nitrogen fixation, ammonification (reduction of organic compounds to ammonia), nitrification (two-step process of oxidation of ammonium to nitrate) and denitrification (conversion of nitrate to gaseous nitrogen). Nitrogen fixation is the most important source of biologically available nitrogen in the biosphere. The intensity of microbial processes in soil depends on type of soil, its humidity, oxygenation, kind of vegetation and fertilization. Acidity of soil also exerts influence on the nitrogen cycle. For most microbial species, their growth is optimal in neutral conditions. In acid soils activity of microorganism is inhibited.
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