Probing multivalent interactions in a synthetic host-guest complex by dynamic force spectroscopy

Multivalency is present in many biological and synthetic systems. Successful application of multivalency depends on a correct understanding of the thermodynamics and kinetics of this phenomenon. In this Article, we address the stability and strength of multivalent bonds with force spectroscopy techniques employing a synthetic adamantane/β-cyclodextrin model system. Comparing the experimental findings to theoretical predictions for the rupture force and the kinetic off-rate, we find that when the valency of the complex is increased from mono- to di- to trivalent, there is a transition from quasi-equilibrium, with a constant rupture force of 99 pN, to a kinetically dependent state, with loading-rate-dependent rupture forces from 140 to 184 pN (divalent) and 175 to 210 pN (trivalent). Additional binding geometries, parallel monovalent ruptures, single-bound divalent ruptures, and single- and double-bound trivalent ruptures are identified. The experimental kinetic off-rates of the multivalent complexes show that the stability of the complexes is significantly enhanced with the number of bonds, in agreement with the predictions of a noncooperative multivalent model

Validation of Drug-Like Inhibitors against Mycobacterium Tuberculosis L-Aspartate α-Decarboxylase Using Nuclear Magnetic Resonance (1H NMR)

10.1371/journal.pone.0045947PLoS ONE79

Chromosome-End Knockoff Strategy to Reshape Alkaloid Profiles of a Fungal Endophyte

Molecular genetic techniques to precisely eliminate genes in asexual filamentous fungi require the introduction of a marker gene into the target genome. We developed a novel strategy to eliminate genes or gene clusters located in subterminal regions of chromosomes, and then eliminate the marker gene and vector backbone used in the transformation procedure. Because many toxin gene clusters are subterminal, this method is particularly suited to generating nontoxic fungal strains. We tested this technique on Epichloë coenophiala, a seed-transmissible symbiotic fungus (endophyte) of the important forage grass, tall fescue (Lolium arundinaceum). The endophyte is necessary for maximal productivity and sustainability of this grass but can produce ergot alkaloids such as ergovaline, which are toxic to livestock. The genome sequence of E. coenophiala strain e19 revealed two paralogous ergot alkaloid biosynthesis gene clusters, designated EAS1 and EAS2. EAS1 was apparently subterminal, and the lpsB copy in EAS2 had a frame-shift mutation. We designed a vector with a fungal-active hygromycin phosphotransferase gene (hph), an lpsA1 gene fragment for homologous recombination at the telomere-distal end of EAS1, and a telomere repeat array positioned to drive spontaneous loss of hph and other vector sequences, and to stabilize the new chromosome end. We transformed E. coenophiala with this vector, then selected “knockoff” endophyte strains, confirmed by genome sequencing to lack 162 kb of a chromosome end including most of EAS1, and also to lack vector sequences. These ∆EAS1 knockoff strains produced no detectable ergovaline, whereas complementation with functional lpsB restored ergovaline production

IMPACTUL CORTICOTERAPIEI INHALATORII ASUPRA CURBEI DE CREŞTERE LA COPIII CU ASTM BRONŞIC

Impactul corticoterapiei inhalatorii (CSI) asupra curbei de creştere staturo-ponderale pe termen lung la copiii cu astm bronşic rămâne o problemă controversată. Obiectivul studiului a fost de a evalua infl uenţa CSI administrată pe termen lung (2 ani) asupra parametrilor de creştere (talie, greutate, indice de masă corporală – IMC) la copiii cu astm bronşic. Metodă: au fost selectaţi pentru studiu 76 de copii (5-18 ani) cu astm persistent uşor – sever care au primit corticoterapie inhalatorie asociat cu bronhodilatator cu durată lungă de acţiune sau/şi montelukast sodic conform GINA 2006. Au fost urmărită în dinamică relaţia doză CSI – curbă de creştere, iar datele obţinute comparate cu cele ale unui lot martor (75 de cazuri) folosind scorul z. Rezultate: datele obţinute în urma folosirii CSI pe o perioadă de 2 ani la copii astmatici în diferite trepte de severitate indică o încetinire a curbei de creştere statuare mai ales în al doilea an al studiului (p = 0,012), fără a infl uenţa semnifi cativ statistic greutatea sau IMC. Nu s-a găsit o corelaţie între doza de CSI administrată (mică, medie, mare) şi curba taliei, a greutăţii şi valoarea IMC. Concluzii: CSI administrată perioadă lungă de tip ar putea afecta ritmul de creştere statuară la copiii astmatici în orice treaptă de severitate a bolii şi indiferent de doza administrată, fără a afecta semnifi cativ greutatea sau IM

Contribution to the knowledge of the micromycetes from the spontaneous flora identified in Iasi county region, Romania

Permanent knowledge of distribution, diversity and interactions between organisms, plants and the environment in which they live is extremely important for the conservation of biodiversity. Interest for biodiversity conservation is intensified by concern bout the conservation of genetic resources, destruction of forest, extinction of species and the effects of global warming. This paper presents some parasitic micromycetes identified on plant species from different areas of Iasi County. In our fieldwork made in the spring of 2021 year were indentified some parasitic micromycetes to spontaneous flora species as: fumewort (Corydalis solida L. Clairv.), alpine squill (Scilla bifolia L.), buttercup anemone (Anemone ranunculoides), lesser celandine (Ranunculus ficaria L.) și snake's head fritillary (Fritillaria meleagrioides Patrin ex Schult. & Schult. f.) Identified micromycetes cause some plant diseases as downy mildew or rust and this fungi species belong to some different taxonomy: Those who cause downy mildew are from Oomycetes class, and rust are from Teliomycetes class as Tranzschelia, Puccinia.și Uromyces genera

Release of overpressures in computational simulations of air-methane explosions

Research in the field of gas explosions has had and continues to have, as its main support, physical experiments performed on various scale models, the construction of real size models are often large consuming materials, time and labor. The rapid development of computing techniques has allowed among other things, the transfer of gas explosions research in the virtual space, for the validation of computational simulations of this type being still considered physical experiments and specialty literature. Within NIRD INSEMEX Petrosani, being an accredited institute in the elaboration of technical reports for gas explosion type events, the phenomenon of rapid combustion virtualization increased in time and as a result, computational simulations becoming an efficient tools in explaining the mechanisms of explosion production. Nevertheless, one of the problems raised by this virtualization process is the limitation of performing computational simulations in closed or partially closed spaces, initial conditions imposed, without the possibility of dynamic modification of these conditions according to the development of overpressures generated by the virtual explosion. This paper presents a computational experiment in which it was possible to transform the boundary conditions at predefined pressure thresholds, from rigid surfaces into surfaces capable of releasing the overpressures developed in closed / partially closed spaces, putting the results of this kind of simulations in line with real dynamic effects of gas explosion events

Analysis of deoxynivalenol in cereals and foods derived from them, at the level of Iasi county

The paper presents information on deoxynivalenol contamination of cereals and food products derived from them, in Iasi County, in the 2015-2019 study interval. Data are presented on the incidence of deoxynivalenol, which has a negative influence on food safety, with a negative impact on the consumer’s health. The study was conducted to assess the level of contamination of cereals and food products derived from them in Iasi County and to adopt European Commission regulations on maximum levels of mycotoxins in various raw materials and products for human consumption.The method used for the study is a direct competitive enzyme-linked immunosorbent assay (ELISA), which allows to obtain exact concentrations for the studied mycotoxin, expressed in µg / kg. The obtained results were within the maximum limits allowed by the current specific legislation

Downregulation of 26S proteasome catalytic activity promotes epithelial-mesenchymal transition.

The epithelial-mesenchymal transition (EMT) endows carcinoma cells with phenotypic plasticity that can facilitate the formation of cancer stem cells (CSCs) and contribute to the metastatic cascade. While there is substantial support for the role of EMT in driving cancer cell dissemination, less is known about the intracellular molecular mechanisms that govern formation of CSCs via EMT. Here we show that β2 and β5 proteasome subunit activity is downregulated during EMT in immortalized human mammary epithelial cells. Moreover, selective proteasome inhibition enabled mammary epithelial cells to acquire certain morphologic and functional characteristics reminiscent of cancer stem cells, including CD44 expression, self-renewal, and tumor formation. Transcriptomic analyses suggested that proteasome-inhibited cells share gene expression signatures with cells that have undergone EMT, in part, through modulation of the TGF-β signaling pathway. These findings suggest that selective downregulation of proteasome activity in mammary epithelial cells can initiate the EMT program and acquisition of a cancer stem cell-like phenotype. As proteasome inhibitors become increasingly used in cancer treatment, our findings highlight a potential risk of these therapeutic strategies and suggest a possible mechanism by which carcinoma cells may escape from proteasome inhibitor-based therapy

Occurrence and frequency of powdery mildew (Blumeria graminis f.Sp. tritici) of winter wheat in Nord-East of Romania, between 2015-2018

Wheat crop are damaged by numerous pathogens, which can produce important yields losses. Blumeria graminis (DC.) E.O. Speer f.sp. tritici Em. Marchal, anamorph Oidium monilioides Link. is an important pathogen present annually in wheat fields, and yield losses attributed to this disease range from 13% to 34%, when the degree of infestation is low, but in the cases when the pressure of infection is high the losses can be over 50%, reaching even the total production compromise. The paper presented the behavior of 35 winter wheat cultivars, represented by Romanian varieties: 11368G1, 11424G1, 11838G8, Boema, Glosa, Izvor, Litera, Miranda FDL, Otilia, Pajura, Pitar, Semnal, Unitar, Ursita, Vestitor, Voevod, Voinic, Zamolxe, Zina, Zamfira, respectively from A.R.D.S. Turda: Andrada, Codru, Dumbrava, T.19-10, T.42-05, T.55-01, T.62-01, T.95-12, T.109-12, T.118-11, T.123-11, T.124-11, T.143-11, T.150-11 and Bezostaia 1 (control variant) based on the dates obtained in three years of field trials (2015-2018), performing at Didactic Station Iasi - Ezăreni Farm. The winter wheat varieties exhibited a wide variability over the studied pathogen, during the study period, variability determined by the characteristics of the agricultural year and by each winter wheat variety

Crop species and year seasons as determinants of microbiota structure in chernozem soil in the southeast region of Moldavia, Romania

In this study, we examined the diversity and abundance of microbial communities isolated from chernozem soil type in response to crop species and season from southeast region of Moldavia, Romania. Soil types, plant species, season, human activities and various land management regimes all have great impact on soil biology, but our knowledge of biodiversity of soil microorganisms is still very limited. Therefore, during 2018 we assessed the variation of microbial community in chernozem soil and its response to plant species (rapeseed, sunflower, sugar beet, wheat and maize) and season (spring, autumn). At each site, five replicate bulk samples were taken, consisting of 10 randomly collected subsamples from the surface soil (10-15 cm horizon). The samples were transported to the laboratory, stored overnight at 4°C, air-dried at room temperature and sieved (2-mm mesh) prior to further use in the experiment. The influence of crop species and season on the total number of microorganisms (CFU g -1 ), relationships between the main groups (bacteria and fungi) and the spectrum of filamentous fungi from our experiment were established. The abundance of the microbial community from all crop species were ranked as follows: wheat (19.2 x 106 CFU g–1 ) > sunflower (1.3 x 106 CFU g–1 ) > maize (1.1 x 106 CFU g–1 ) > sugar beet (0.6 x 106 CFU g–1 ) > rapeseed (0.4 x 106 CFU g–1 ). In case of yearly seasons, the microbial abundance decreased from spring to autumn. Occurrence and distribution of filamentous fungi isolated from soil samples provide new insights into ecology and niche specialization of several soil-borne species. Overall, genera composition of filamentous fungi from chernozem soil cultivated with different crop species was not very heterogeneous and most fungal genera were common to all location. Our results suggest that crop species and yearly seasons have a significant impact on microbial richness and diversity. Extensive use of xenobiotic compounds in agriculture will degrade soil microbial communities, because they affect directly microbial abundance and composition, and indirectly soil texture and fertility