Tributyltin-resistant Methanothermobacter thermautotrophicus mutant with mutational substitutions in the A1A0-ATP synthase operon

A spontaneous mutant of Methanothermobacter thermautotrophicus resistant to tributyltin chloride (TBT) was isolated. TBT, the inhibitor of the A₀ domain of A₁A₀-ATP synthase, inhibits methanogenesis in the wild-type cells; however, the TBT-resistant mutant exhibited methanogenesis even in the presence of 800 μM TBT. ATP synthesis driven by methanogenic electron transport was markedly diminished in the mutant strain. While TBT profoundly inhibited ATP synthesis driven by methanogenic electron transport in the wild type, only a slight inhibition was observed in the mutant strain. These results suggested a modification in the ATP-synthesizing system of the mutant strain. The sequence of the complete A₁A₀-ATP synthase operon ( Mth952 – Mth961 ) in the wild-type and mutant strains was determined and compared. Three mutations leading to amino acid substitutions in two A₁A₀-ATP synthase subunits were identified – Val₃₃₈Ala in subunit A and Leu₂₅₂Ile and Ser₂₉₃Ala in subunit B. Moreover, this study revealed the differential expression of several proteins that may contribute to TBT resistance. The results imply that change of TBT sensitivities of TBT-resistant mutant is due to mutational substitutions in the A₁A₀-ATP synthase operon.     

Remote locality of the littoral Carex extensa (Cyperaceae) in Hungary — long distance dispersal from coastal to inland salt marshes

A remarkable population of Carex extensa (Cyperaceae) was found south of Lake Fert? (Neusiedler See) in Hungary in 2012. This species typically occurs in coastal salt marshes in Europe and was hitherto unknown from the Pannonian Basin. The locality is situated in a territory which has been embanked in 1911. Keeping also in mind that the vegetation developed here from reed beds to saline habitats, we conclude that C. extensa reached the salt marshes of the area through long distance dispersal by water birds from the European coast in the last century. Nevertheless, several other maritime littoral species grow in the region, and the possibility that there is a hidden population of C. extensa at another site(s) nearby cannot be excluded. Lake Fert? is often described as the “westernmost steppe lake” and supports one of the richest European inland littoral floras. Although it appears likely that C. extensa has only recently colonised the site, we consider this discovery to be of significant biogeographical importance.     

Patterns of aggregation behaviour in six species of cockroach: comparing two experimental approaches

Cockroaches (Blattaria) are considered universally gregarious insects. In this study, we tested the hypothesis that even related species and/or males and females of the same species may exhibit different aggregation patterns. We compared aggregation behaviour in six cockroach species belonging to three groups: Eublaberus, Blaberus, and Gromphadorhina‐Princisia (all Blaberidae). For comparison, binary choice and free aggregation arena tests were used. The results revealed that blaberid clades clearly differed in their aggregation patterns. Females of Eublaberus species aggregated, whereas only a low aggregation tendency was recorded in conspecific males. Both sexes of Blaberus species aggregated, especially when tested in the arena. The Madagascar hissing cockroaches of the Gromphadorhina‐Princisia clade are not gregarious – the aggregation tendency was entirely absent in males of the two species studied and in females of Princisia vanwaerebeki van Herrewege, and was only weakly demonstrated in females of Gromphadorhina portentosa (Schaum). The observed patterns of aggregation are compared with previous reports concerning social behaviour of blaberid species.     

Can tissue element concentration patterns at the individual species level indicate the factors underlying vegetation gradients in wetlands?

Question: Do tissue element concentrations at the individual species level vary along major vegetation gradients in wetlands, and can they indicate environmental conditions? Location: West Carpathians. Methods: Total plant species composition was recorded in plots distributed along a poor to rich gradient within spring fens and along the gradient from fens to wet meadows. Eriophorum angustifolium (Cyperaceae) and three broadleaf dicotyledonous herb species were collected from the vegetation plots. Tissue N, P, K, Ca and Fe concentrations, N:P and N:K ratios of the species were determined. Each variable was correlated with the sample scores along the first two axes of the DCA ordination, which represented the two main vegetation gradients. Results: K and Ca concentrations in a particular species correlated well with the vegetation gradients, thus indicating changes in the element availability to the species. The trends were sometimes contradictory to known patterns at the community level, but the differences could be ecologically interpreted. Contrary to Ca and K, patterns in N, P and Fe concentration appeared to be more species‐specific. E. angustifolium had a lower K and Ca concentration than the broadleaf herbs. Conclusions: Compared to community‐level measurements, element concentrations in individual species correlated less with observed vegetation gradients. Trends found at the species level may indicate changes in ecological conditions affecting the species, although they need not correspond with trends found at the community level. We conclude that the species‐level approach cannot substitute, but can advance, the community‐level approach in searching for mechanisms underlying vegetation gradients within wetlands.     

Signatures of antagonistic pleiotropy in a bacterial flagellin epitope

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Immunohistochemical visualisation of the enteric nervous system architecture in the germ-free piglets

Journal of Molecular Histology - The enteric nervous system (ENS), considered as separate branch of the autonomic nervous system, is located throughout the length of the gastrointestinal tract as a...     

Genetic distances,geographic distances and migration between four villages of a single region in Slovakia

Genetic microdifferentiation has been studied among four endogamous villages of the Bystrica Valley in the Kysuce region of northwest Slovakia, which arose from a single ancestral population about 15 generations ago. Genetic distances and sample kinship between the villages were estimated from the gene frequencies of seven serum-group and isozyme genetic markers. The genetic distance was found to correlate positively (though insignificantly) with the geographic distance, and negatively with the intensity of migration between villages; the sample kinship correlates negatively with geography as well as with the genetic distance. This pattern of genetic structure within the area indicates that the genetic variation among the villages is attributable to the genetic drift. Thus, drift has brought about a detectable differentiation in the area within a limited period of approximately 300 years, in spite of the fact that the villages were not completely genetically isolated from each other. The finding of a negative correlation between the sample kinship and geographic distance indicates that the recent breakdown of genetic isolates in Slovakia is likely to be accompanied with an overall increase of heterozygosity.     

Genetic variability of plant-associated proteobacteria isolated from Slovak (Central European) territory

Genetic variability of 17 wild strains of γ-proteobacteria isolated from different host plants, locations and seasons, identified via routine diagnostics as Erwinia amylovora, was analysed. The ERIC-PCR confirmed the genetic homogeneity among 15 virulent strains while 2 avirulent strains were genetically distinct. These two avirulent strains differed in their antibiotic susceptibility from all virulent strains. The only avirulent Ra1051/98 strain showed significant ampicillin resistance. All 15 virulent strains were confirmed via the ERIC-PCR and MALDI-TOF MS, as closely related to the reference strain NCPPB 683 of E. amylovora. Avirulent strains were identified as Rahnella aquatilis and L. quercina subsp. britannica (formerly Brenneria quercina), by MALDI-TOF MS and the identification was confirmed by 16S rRNA gene sequence analysis. For the first time, L. quercina subsp britannica was identified in the fire blight-symptomatic samples in Central Europe, and for the first time this bacterium was isolated from the host different than oak.