Formate hydrogenlyase and formate secretion ameliorate H2 inhibition in the hyperthermophilic archaeon Thermococcus paralvinellae

Some hyperthermophilic heterotrophs in the genus Thermococcus produce H₂ in the absence of S° and have up to seven hydrogenases, but their combined physiological roles are unclear. Here, we show which hydrogenases in Thermococcus paralvinellae are affected by added H₂ during growth without S°. Growth rates and steady‐state cell concentrations decreased while formate production rates increased when T. paralvinallae was grown in a chemostat with 65 µM of added H_2(aq). Differential gene expression analysis using RNA‐Seq showed consistent expression of six hydrogenase operons with and without added H₂. In contrast, expression of the formate hydrogenlyase 1 (fhl1) operon increased with added H₂. Flux balance analysis showed H₂ oxidation and formate production using FHL became an alternate route for electron disposal during H₂ inhibition with a concomitant increase in growth rate relative to cells without FHL. T. paralvinellae also grew on formate with an increase in H₂ production rate relative to growth on maltose or tryptone. Growth on formate increased fhl1 expression but decreased expression of all other hydrogenases. Therefore, Thermococcus that possess fhl1 have a competitive advantage over other Thermococcus species in hot subsurface environments where organic substrates are present, S° is absent and slow H₂ efflux causes growth inhibition.     

Improvement of photovoltaic performance by substituent effect of donor and acceptor structure of TPA-based dye-sensitized solar cells

We report a computational study of a series of organic dyes built with triphenylamine (TPA) as an electron donor group. We designed a set of six dyes called (TPA-n, where n?=?0–5). In order to enhance the electron-injection process, the electron-donor effect of some specific substituent was studied. Thus, we gave insights into the rational design of organic TPA-based chromophores for use in dye-sensitized solar cells (DSSCs). In addition, we report the HOMO, LUMO, the calculated excited state oxidized potential E^dye*(eV) and the free energy change for electron-injection ΔG_inject(eV), and the UV-visible absorption bands for TPA-n dyes by a time-dependent density functional theory (TDDFT) procedure at the B3LYP and CAM-B3LYP levels with solvent effect. The results demonstrate that the introduction of the electron-acceptor groups produces an intramolecular charge transfer showing a shift of the absorption wavelengths of TPA-n under studies.

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Graphical Abstract Several organic dyes TPA-n with different donors and acceptors are modeled. A strong conjugation acrros the donor and anchoring groips (TPA-n) bas been studied. Candidate TPA-3 shows a promising results.

     

Evaluation of PCR Approaches for Detection of Bartonella bacilliformis in Blood Samples

BackgroundThe lack of an effective diagnostic tool for Carrion’s disease leads to misdiagnosis, wrong treatments and perpetuation of asymptomatic carriers living in endemic areas. Conventional PCR approaches have been reported as a diagnostic technique. However, the detection limit of these techniques is not clear as well as if its usefulness in low bacteriemia cases. The aim of this study was to evaluate the detection limit of 3 PCR approaches.Conclusions/SignificanceFrom the tested PCRs, the 16S rRNA PCR-approach is the best to be used in the direct blood detection of acute cases of Carrion’s disease. However its use in samples from dry blood spots results in easier management of transport samples in rural areas, a slight decrease in the sensitivity was observed. The usefulness to detect by PCR the presence of low-bacteriemic or asymptomatic carriers is doubtful, showing the need to search for new more sensible techniques.     

Immunodiffusion Analysis of Isolates of Xanthomonas cyamopsidis

Immunodiffusion analysis of intact, sonically treated, and sonically treated and heat-treated cell antigen preparations of isolates of races 0 and 1 of Xanthomonas cyamopsidis of guar, Cyamopsis tetragonoloba, indicated that these races differ from one another antigenically. The differentiating precipitin reactions are believed to have been brought about by specific heat-stable surface antigens, possibly similar to lipopolysaccaride somatic antigens of other slime-producing xanthomonads. Because differences in host reaction to inoculation with the two isolates of race 1 were known to be minor, these isolates are considered to represent serotypes of the race rather than distinct separate races. This conclusion is supported by the antigenic behavior of isolates 14 and 19 to antiserum 19. The applicability of immunodiffusion analysis for the study of pathogenic variability in X. cyamopsidis is demonstrated.     

Chemical and physiological changes in filamentous fungi during autolysis. X. Changes in the concentration of polyol in autolysing cultures of several fungi

Botrytis cinerea, Colletotrichum gloeosporioides, Aspergillus niger andPenicillium griseofulvum were grown in flasks as stationary cultures in the ordinary Czapek-Dox medium at 24° C in the dark for long periods of time. At convenient intervals during autolysis samples of mycelium were harvested and its polyol content determined. The loss of mycelial mannitol during autolysis reached to a little more than 60 %, more than 70 %, to nearly 80 % and 90 % forC. gloeosporioides, P. griseofulvum, A. niger andB. cinerea, respectively. Seventy per cent of the arabitol contained inP. griseofulvum and 85 % of the arabitol inC. gloeosporioides disappeared during autolysis. Mannitol remained present in appreciable amounts in these four fungi throughout the whole period of autolysis described, whereas arabitol disappeared fromB. cinerea and fromA. niger during the process.

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Zusammenfassung Botrytis cinerea, Colletotrichum gloeosporioides, Aspergillus niger undPenicillium griseofulvum sind als stationäre Kulturen in Czapek-Dox Nährboden bei 24° C lange Zeit in der Dunkelheit gezüchtet worden. In geeigneten Zwischenzeiten sind während der Autolyse Myzeliumproben entnommen und ihr Polyol-Inhalt bestimmt. Der Verlust vom myzelialen Mannitol während der Autolyse erreichte mehr als 60 %, mehr als 70 %, beinahe 80 % und 90 % inC. gloeosporioides, P. griseofulvum, A. niger, undB. cinerea, beziehungsweise. Siebzig Prozent von Arabitol inP. griseofulvum und 85 % von Arabitol inC. gloeosporioides verschwanden während der Autolyse. Mannitol verblieb in beträchtlicher Menge in diesen vier Pilzen während der ganzen Periode der Autolyse, während Arabitol vonB. cinerea und vonA. niger in derselben Zeit verschwand.

     

Growth and Nitrogen Fixation Activity of Soybeans in the Presence of Bean Pod Mottle Virus

Pathological and physiological responses associated with the host-microsymbiont interaction of soybeans (Glycine max‘Franklin’, ‘Dyer’, ‘Centennial’, ‘Marshall’, ‘Williams’, ‘Bedford’, and ‘Peking’), which were nodulated with Rhizobium japonicum (USDA strain 3I1b-110) and inoculated with bean pod mottle virus (BPMV) in the greenhouse, varied with the cultivar and the substrate in which the plants were grown. In plants grown in a soil mixture, the virus significantly reduced canopy growth, nodulation, total N, and ureide-N content of most cultivars but symbiotic N₂ fixation was significantly reduced only for ‘Centennial’ and ‘Peking’. In vermiculite, in which the plants depended almost exclusively on symbiotically fixed N_,2, the virus reduced canopy and nodule mass of some cultivars but these reductions were significant only for ‘Franklin’. In plants grown in this substrate, however, the virus had little effect as increases or decreases in measured components of symbiotic N metabolism were nonsignificant except for the increase in leaf ureides in ‘Marshall’. Results suggest that in either soil or vermiculite the symbiotic process in certain soybean cultivars can function at nearly a normal level despite root noduleinfection with this virus.     

Potentiation of diacylglycerol-activated protein kinase C by acyl-coenzyme A thioesters of hypolipidaemic drugs

Acyl-Coenzyme A thioesters of the hypolipidaemic and cancerinogenic peroxisome proliferators clofibric acid, nafenopin, ciprofibrate, bezafibrate and tibric acid were found to greatly increase the activity of rat brain protein kinase C. Maximal activation required the simultaneous presence of Ca+2, phosphatidylserine and diolein, thus differentiating their action from that of other tumor promoters such as phorbol esters. Under similar conditions the unesterified drugs were comparatively ineffective. Similar results were obtained using the rat liver enzyme. The data suggest that acylcoenzyme A thioesters of hypolipidaemic drugs, may play a role in the induction of liver tumors by these compounds, through the potentiation of protein kinase C.     

In vitro synthesis of myelin proteolipid protein from rat brain using a total homogenate system

In vitro synthesis of myelin proteolipid protein (PLP) was explored at different ages using rat brain total homogenates, incubated for 30 min with [³H]glycine. Total proteolipids, extracted from the incubated samples, were separated by SDSPAGE and the radioactivity was measured in the band corresponding to myelin PLP. The incorporation into PLP in relation to the incorporation into brain total proteins increased from 0.04% at 10 days of age to 0.63% at 20 days, and declined slowly thereafter. Time course experiments were carried out using brain homogenates obtained from rats of 20 days of age (i.e. at the period of maximal synthesis of PLP). Labeled PLP molecules were already found at 2.5 min of incubation and the incorporation of the label into this protein, relative to the incorporation into total proteins, did not vary throughout the entire incubation time (30 min). Pulsechase experiments using a similar system and adding cycloheximide at different incubation times showed that the appearance of label into mature PLP was immediately blocked by the inhibitor of protein synthesis. These data suggest that PLP is synthesized as such and not as a pre-protein which is subsequently processed to render mature PLP.     

Cell membrane permeabilization via connexin hemichannels in living and dying cells

Vertebrate cells that express connexins likely express connexin hemichannels (Cx HCs) at their surface. In diverse cell types, surface Cx HCs can open to serve as a diffusional exchange pathway for ions and small molecules across the cell membrane. Most cells, if not all, also express pannexins that form hemichannels and increase the cell membrane permeability but are not addressed in this review. To date, most characterizations of Cx HCs have utilized cultured cells under resting conditions have and revealed low open probability and unitary conductance close to double that of the corresponding gap junction channels. In addition, the cell membrane permeability through Cx HCs can be markedly affected within seconds to minutes by various changes in the intra and/or extracellular microenvironment (i.e., pH, pCa, redox state, transmembrane voltage and intracellular regulatory proteins) that affect levels, open probability and/or (single channel) permeability of Cx HC. Net increase or decrease in membrane permeability could result from the simultaneous interaction of different mechanisms that affect hemichannels. The permeability of Cx HCs is controlled by complex signaling cascades showing connexin, cell and cell stage dependency. Changes in membrane permeability via hemichannels can have positive consequences in some cells (mainly in healthy cells), whereas in others (mainly in cells affected by acquired and/or genetic diseases) hemichannel activation can be detrimental.     

Hypochaeris alliatae group (Asteraceae) in the western Mediterranean Region

A taxonomic, ecological, and phytogeographical revision of the Hypochaeris alliatae group is made. As a result, the name of H. alliatae (vs H. laevigata ) is proposed. The recent taxa H. leontodontoides var. glauca and H. rutea are synonymised with H. alliatae , and H. leontodontoides var. atlantica var. nov ., is described. Using chromosomal counts, morphological and histological characters, H. angustifolia is excluded from the H. alliatae group. A phylogenetic and phytogeographical assay has been made in the context of geologic phenomena from the Miocene and Pliocene in the western Mediterranean Basin.