Arrangement of the electric potential-generating redox chain in the mitochondrial membrane

The intramembrane arrangement of the respiratory chain generating electric potential difference across the mitochondrial membrane has been studied. The accessibility of various respiratory carriers to the non-penetrating electron donors and acceptors, such as ferri-and ferrocyanide, cytochrome c. fumarate and nicotinamide nuclcotides has been used as a test for surface localization of the carrier in the membrane of mitochondria and inside-out (sonicated) submitochondrial particles. Membrane potential formation was detected by measuring the transmembrane flows of the penetrating anion, phenyl dicarbaundecaborne (PCB^–).It is shown that ferricyanide reduction can support PCB^– movement if this electron acceptor interacts with intact mitochondria in the region localized on the oxygen site of the antimycin-sensitive point. The same region is accessible for ferrocyanide whose oxidation by O₂ can be also coupled with PCB^– translocation. Added nicotinamide nuclcotides cannot be utilized by mitochondria for supporting PCB^– movement.PCB^– movement in the inside-out submitochondrial particles can be supported by reduction of ferricyanide or fumarate by NADH, and of NAD⁺ by NADPH, the former process being sensitive to rotenone but not to antimycin. Antimycin-insensitive reduction of feericyanide or of CoQ₆ by succinate is not coupled with PCB^– transport. Neither ferrocyanide nor ferrocytochromec can be used as electron donors in the particles.Penetrating electron donors (TMPDH₂, succinate) and acceptors (menadione) are effective both in mitochondria and particles.It is coucluded that flavin and transhydrogenase regions of the potential-generating redox chain are localized near the inner surface, cytochromec region-near the outers surface of the internal membrane of intact mitochondria. It means that the redox chain includes at least one act of the transmembrane transfer of reducing equivalents between flavins and cytochromec.     

Biodiesel fuel from microalgae-promising alternative fuel for the future: a review

The use of organic matter such as vegetable oil to produce biodiesel fuel has been a practical technology for a number of years. However, the search for new technologies and raw materials for biodiesel fuel production has gained increased attention recently because of financial and environmental concerns. Of particular interest are raw materials that are not food-related. Microalgae have gained a great deal of attention as a potential biodiesel raw material because of their high growth rates and ability to accumulate oil, bind carbon dioxide, and remove contaminants from wastewater. This article is a literature review of technologies for biodiesel production from microalgae. The technologies relate to microalgal cultivation, microalgal growth enhancement to simultaneously increase biomass and reduce pollution, the preparation of microalgal biomass for biodiesel production, and biodiesel production itself.     

Clonal structure and reduced diversity of the invasive alien plant Erigeron annuus in Lithuania

The alien species Erigeron annuus (L.) Pers. is in an intensive spreading phase in Lithuania. Random amplified polymorphic DNA (RAPDs) and inter-simple sequence repeats (ISSRs) assays were used to study the genetic structure of old and new invasive populations and to determine the most spread genotypes of this species in Lithuania. Pairwise genetic distances between populations established using RAPD and ISSR markers significantly correlated (r=0.91, P<0.05). Our study indicates that there are two genetically different types of E. annuus populations. The first type is represented by a widely spread main clone and related monomorphic populations. The second type is represented by polymorphic populations, some of them present at sites where E. annuus has not been previously observed. Main clone predominates in nine populations and is from the region where this species was first described in natural ecosystems of Lithuania. UPGMA cluster analysis revealed genetic relationships between the main clone and accessions from old cemeteries where E. annuus has been grown as an ornamental plant. We found high genetic differentiation among populations (G _ST=0.58 for RAPDs, G _ST=0.64 for ISSRs). Taken together, our results will contribute to the monitoring of E. annuus spread in Lithuania.     

Induction of apoptosis and activation of JNK and p38 MAPK pathways in deoxynivalenol-treated cell lines

Deoxynivalenol (DON) is a mycotoxin produced by what are thought to be the most prevalent toxin-producing fungi of the Fusarium genus. Here, we present the results of apoptosis induction, phosphorylation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPKs), and expression of the c-Jun protein after DON treatment, in a pre-B lymphocyte REH cell line. In addition, human pre-T lymphocyte Jurkat, hamster kidney-derived BHK21 and mouse hepatoma MH-22a cells were used in comparative experiments in vitro. We found that the DON effect was cell origin-dependent and dose-dependent, with a significant slow-down of cell proliferation and increase of apoptotic cells in blood cell lines. BHK21 and MH-22a cells were less sensitive to the DON effect. In blood-derived REH and Jurkat cells, DON-induced apoptotic changes were preceded by an increase in JNK and p38 MAPKs phosphorylation, as well as in c-Jun expression. However, the activation of JNK phosphorylation and c-Jun expression were transient, but did not coincide with each other. An inhibitor of JNK1/2, SP600125, had a negligible negative effect on REH cell viability after DON treatment, demonstrating that JNK does not contribute to DON-induced apoptosis. In contrast, studies on the role of p38 MAPK revealed that p38 signalling is required for DON-induced apoptosis in REH cells.     

Environmental and synthetic sulphydryl group inhibitors: effects on bioluminescence and respiration in Vibrio fischeri

Elemental sulphur (as S0 and S8) is abundant in anaerobic sediments and soil, and is highly toxic in the Vibrio fischeri bioluminescence test. This mode of S0 action remains uncertain. The objective of this research was the analysis of the toxic effects of S0 on bioluminescence and respiration in V. fischeri, in joint action with N-ethylmaleimide (NEM) or 2,4-dithio-DL-threitol (DTT), which are -SH group inhibiting and maintaining synthetic agents, respectively. Non-toxic DTT immediately protected cell bioluminescence against S0 inhibition at low (5.5ppb) and high (55ppb) concentrations of S0, whilst restoration of the inhibitory effect of S0 took up to 30 minutes. NEM (62.5ppb) diminished cell bioluminescence by up to 50% after 5 minutes, but after 60 minutes, the inhibition reached 100%. DTT restored the bioluminescence function inhibited in vivo and in vitro by S0 and NEM. Enhancement of cell respiration by up to 20% and 33% was observed at 2.2ppm of S0 and 36.8ppm of 2,4-dinitrophenol (2,4-DNP; an uncoupler of oxidative phosphorylation), respectively; whilst NEM (3.1ppm) caused a reduction of up to 40%. This comparative analysis confirmed that S0 has multiple modes of action--it acts as both an -SH group inhibitor and an uncoupler of oxidative phosphorylation in V. fischeri cells.     

Identification and functional analysis of the Rz/Rz1-like accessory lysis genes in the membrane-containing bacteriophage PRD1

Bacteriophage PRD1 is a tailless membrane-containing double-stranded (ds) DNA virus infecting a variety of Gram-negative bacteria. In order to affect cell lysis, like most dsDNA phages, PRD1 uses the holin-endolysin system. In this study, we identified two accessory lysis genes, XXXVI and XXXVII , coding for proteins P36 and P37, respectively. Using genetic complementation assays, we show that protein pair P36/P37 is a functional and interchangeable analogue of the Rz/Rz1 of bacteriophage λ. Utilizing molecular biology, electrochemical as well as various microscopic techniques, we characterized the lysis phenotypes of PRD1 host cells infected with mutant viruses. Our results indicate that proteins P36 and P37 confer a competitive advantage to the phage by securing the efficient disruption of the infected cell and consequent release of the phage progeny under less favourable growth conditions. In concordance with prior data and the results obtained in this study, we propose a model explaining the role of Rz/Rz1-like proteins in the lysis process: Rz/Rz1 complexes transform the mechanical stress caused by the holin lesion at the CM to the OM leading to its disintegration. Finally, identification of the Rz / Rz1 -like genes in PRD1 suggests that tailless icosahedral phages are involved in genetic trade with tailed bacteriophages.