1461 research outputs found
Sort by
Spatial structure of the soil seed bank of Poa annua L.— alien species in the Antarctica
Get PDFAbstract Poa annua L. (annual bluegrass) is the only non–native flowering plant species
that has successfully established a breeding population in the maritime Antarctic and has been
shown to maintain a soil seed bank. The characteristic of the spatial structure of the Antarctic
population of this species is the formation of distinct dense clumps—tussocks. In the temperate
zone the species is only loosely tufted. We focused on the characteristics of seed
deposition associated with the tussocks and some aspects of the spatial heterogeneity of the
soil seed bank of P. annua in the Antarctic. We wanted to assess the microspatial structure of
the soil seed bank of annual bluegrass at Arctowski Station. Therefore we compared the
number of seeds deposited underneath and in the vicinity of P. annua clumps. Our results
indicate that P. annua in the Antarctic maintains a soil seed bank comparable to species typical
for the polar tundra. The microspatial structure of P. annua soil seed bank in the Antarctic is
highly associated with the presence of tussocks. Seeds are deposited underneath the tussock
rather than in the vicinity of the clump. Our results also indicate that seeds are able to survive
the Antarctic winter and readily germinate under optimal conditions
Is DNA methylation modulated by wounding-induced oxidative burst in maize?
Get PDFPlants respond to environmental changes by modifying gene expression. One of the mechanisms regulating gene expression is methylation of cytosine to 5-methylcytosine (m5C) which modulates gene expression by changing chromatin structure. Methylation/demethylation processes affect genes that are controlled upon environmental stresses. Here, on account of the regulatory role of m5C, we evaluate the content of m5C in DNA from normal and wound-damaged maize leaves. Wounding leads to a transient decrease of the global DNA methylation level ca 20-30% 1 hour after the treatment followed by a return to the initial level within the next hours. Similar results were obtained using of radio-labelled nucleotides separated by Thin Layer Chromatography (TLC) or using m5C-specific Enzyme-Linked Immunosorbent Assay (ELISA). Wounding induced in maize leaves a two-step oxidative stress, an early one just after wounding and the second two hours later. It coincides with the transient changes of the cytosine methylation level. In the stress-inducible maize calcium-dependent protein kinase ZmCPK11 gene wounding transiently reduced methylation of cytosines 100 and 126 in the first exon
Intronic T-DNA insertion in Arabidopsis NBR1 conditionally affects wild-type transcript level
Get PDFThe SALK_135513 line of Arabidopsis thaliana is annotated by GenBank to have the
T-DNA insertion in the fourth exon of NBR1 (At4g24690). Careful molecular analyses of the homozygous plants of SALK_135513 line indicated the place of T-DNA insertion in the fourth intron. Unexpectedly, two kinds of NBR1 transcripts, the wild-type and the mutated, resulting from alternative splicing events, were detected in those plants. Our findings explain the problems encountered by us with phenotypic evaluation of this line and emphasize the necessity for independent verification of the exact insertion site followed by careful expression studies when working with Arabidopsis T-DNA insertional mutants
Dissection of the region of Pseudomonas aeruginosa ParA that is important for dimerization and interactions with its partner ParB.
Get PDFPseudomonas aeruginosa ParA belongs to a large subfamily of Walker-type ATPases acting as partitioning proteins in bacteria. ParA has the ability to both self-associate and interact with its partner ParB. Analysis of the deletion mutants defined the part of the protein involved in dimerization and interactions with ParB. Here, a set of ParA alanine substitution mutants in the region between E67 and L85 was created and analysed in vivo and in vitro. All mutants impaired in dimerization (substitutions at positions M74, H79, Y82 and L84) were also defective in interactions with ParB, suggesting that ParA-ParB interactions depend on the ability of ParA to dimerize. Mutants with alanine substitutions at positions E67, C68, L70, E72, F76, Q83 and L85 were not impaired in dimerization, but were defective in interactions with ParB. The dimerization interface partly overlapped the pseudo-hairpin, involved in interactions with ParB. ParA mutant derivatives tested in vitro showed no defects in ATPase activity. Two parA alleles (parA84, whose product can neither self-interact nor interact with ParB, and parA67, whose product is impaired in interactions with ParB, but not in dimerization) were introduced into the P. aeruginosa chromosome by homologous gene exchange. Both mutants showed defective separation of ParB foci, but to different extents. Only PAO1161 parA84 was visibly impaired in terms of chromosome segregation, growth rate and motility, similar to a parA-null mutant
Intrauterine growth retarded piglet as a model for humans--studies on the perinatal development of the gut structure and function.
No full textThe overall acceptance of pig models for human biomedical studies is steadily growing. Results of rodent studies are usually confirmed in pigs before extrapolating them to humans. This applies particularly to gastrointestinal and metabolism research due to similarities between pig and human physiology. In this context, intrauterine growth retarded (IUGR) pig neonate can be regarded as a good model for the better understanding of the IUGR syndrome in humans. In pigs, the induction of IUGR syndrome may include maternal diet intervention, dexamethasone treatment or temporary reduction of blood supply. However, in pigs, like in humans, circa 8% of neonates develop IUGR syndrome spontaneously. Studies on the pig model have shown changes in gut structure, namely a reduced thickness of mucosa and muscle layers, and delayed kinetic of disappearance of vacuolated enterocytes were found in IUGR individuals in comparison with healthy ones. Functional changes include reduced dynamic of gut mucosa rebuilding, decreased activities of main brush border enzymes, and changes in the expression of proteins important for carbohydrate, amino acids, lipid, mineral and vitamin metabolism. Moreover, profiles of intestinal hormones are different in IUGR and non-IUGR piglets. It is suggested that supplementation of the mothers during the gestation and/or the IUGR offspring after birth can help in restoring the development of the gastrointestinal tract. The pig provides presumably the optimal animal model for humans to study gastrointestinal tract structure and function development in IUGR syndrome
Crystal structure of the antimicrobial peptidase lysostaphin from Staphylococcus simulans.
Get PDFStaphylococcus simulans biovar staphylolyticus lysostaphin efficiently cleaves Staphylococcus aureus cell walls. The protein is in late clinical trials as a topical anti-staphylococcal agent, and can be used to prevent staphylococcal growth on artificial surfaces. Moreover, the gene has been both stably engineered into and virally delivered to mice or livestock to obtain resistance against staphylococci. Here, we report the first crystal structure of mature lysostaphin and two structures of its isolated catalytic domain at 3.5, 1.78 and 1.26 Å resolution, respectively. The structure of the mature active enzyme confirms its expected organization into catalytic and cell-wall-targeting domains. It also indicates that the domains are mobile with respect to each other because of the presence of a highly flexible peptide linker. The high-resolution structures of the catalytic domain provide details of Zn(2+) coordination and may serve as a starting point for the engineering of lysostaphin variants with improved biotechnological characteristics
A dual promoter system regulating λ DNA replication initiation
Get PDFTranscription and DNA replication are tightly regulated to ensure coordination of gene expression with growth conditions and faithful transmission of genetic material to progeny. A large body of evidence has accumulated, indicating that encounters between protein machineries carrying out DNA and RNA synthesis occur in vivo and may have important regulatory consequences. This feature may be exacerbated in the case of compact genomes, like the one of bacteriophage λ, used in our study. Transcription that starts at the rightward pR promoter and proceeds through the λ origin of replication and downstream of it was proven to stimulate the initiation of λ DNA replication. Here, we demonstrate that the activity of a convergently oriented pO promoter decreases the efficiency of transcription starting from pR. Our results show, however, that a lack of the functional pO promoter negatively influences λ phage and λ-derived plasmid replication. We present data, suggesting that this effect is evoked by the enhanced level of the pR-driven transcription, occurring in the presence of the defective pO, which may result in the impeded formation of the replication initiation complex. Our data suggest that the cross talk between the two promoters regulates λ DNA replication and coordinates transcription and replication processes
cis-Prenyltransferase AtCPT6 produces a family of very short-chain polyisoprenoids in planta
Get PDFcis-Prenyltransferases (CPTs) comprise a numerous enzymes synthesizing isoprenoid hydrocarbon skeleton with isoprenoid units in the cis (Z) configuration. The chain-length specificity of a particular plant CPT is in most cases unknown despite the composition of the accumulated isoprenoids in the tissue of interest being well established.
In this report AtCPT6, one of the nine Arabidopsis thaliana CPTs, is shown to catalyze the synthesis of a family of very short-chain polyisoprenoid alcohols of six, seven, and eight isoprenoid units, those of seven units dominating. The product specificity of AtCPT6 was established in vivo following its expression in the heterologous system of the yeast Saccharomyces cerevisiae and was confirmed by the absence of specific products in AtCPT6 T-DNA insertion mutants and their overaccumulation in AtCPT6 - overexpressing plants. These observations are additionally validated in silico using an AtCPT6 model obtained by homology modeling.
AtCPT6 only partially complements the function of the yeast homologue of CPT - Rer2 since it restores the growth but not protein glycosylation in rer2Δ yeast. This is the first in planta characterization of specific products of a plant CPT producing polyisoprenoids. Their distribution suggests that a joint activity of several CPTs is required to produce the complex mixture of polyisoprenoid alcohols found in Arabidopsis roots
Analysis of plant polyisoprenoids
Get PDFPolyisoprenoid alcohols are representatives of high-molecular terpenoids. Their hydrocarbon chains are
built of 5 to more than 100 isoprene units giving rise to polymer molecules that differ in chain-length
and/or geometrical configuration. Plants have been shown to accumulate diverse polyisoprenoid mixtures
with tissue-specific composition. In this chapter, methods of analysis of polyisoprenoid alcohols in plant
material are described, including isolation and purification of polyisoprenoids from plant tissue, fast semiquantitative analysis of the polyisoprenoid profile by thin-layer chromatography (straight phase adsorption and reversed phase partition techniques), and quantification of polyisoprenoids with the aid of high performance liquid chromatography. This approach results in full characterization of complex polyisoprenoid mixtures accumulated in various plant tissues and other matrixes
Antibody response to DNA vaccine against H5N1 avian influenza virus in broilers immunized according to three schedules.
Get PDFBroiler type chickens were immunized intramuscularly with a DNA vaccine encoding hemagglutinin (HA) from H5N1 avian influenza virus. The chickens were divided into four groups: control group which was not immunized, a group which obtained only one dose, and two groups which were immunized twice, one group with a boost two weeks after the priming and the other four weeks. Blood samples were collected at several time points and the dynamics of the humoral response to the vaccine was studied. High level of anti-HA antibodies was detected only in the last two groups, that is in chickens immunized according to the prime-boost strategy, regardless of the schedule. An additional interesting observation of this study was detection of the cross-reactivity of an anti-H5 HA positive serum with H5N2 and H1N1 viruses, suggesting that the DNA vaccine tested can induce antibodies of a broad specificity