Combined effect of X‐ray radiation and static magnetic fields on reactive oxygen species in rat lymphocytes in vitro

The aim of this study was to investigate the effect of static magnetic fields (SMF) on reactive oxygen species induced by X‐ray radiation. The experiments were performed on lymphocytes from male albino Wistar rats. After exposure to 3 Gy X‐ray radiation (with a dose rate of 560 mGy/min) the measurement of intracellular reactive oxygen species in lymphocytes, using a fluorescent probe, was done before exposure to the SMF, and after 15 min, 1 and 2 h of exposure to the SMF or a corresponding incubation time. For SMF exposure, 0 mT (50 µT magnetic field induction opposite to the geomagnetic field) and 5 mT fields were chosen. The trend of SMF effects for 0 mT was always opposite that of 5 mT. The first one decreased the rate of fluorescence change, while the latter one increased it. Bioelectromagnetics 34:333–336, 2013. © 2012 Wiley Periodicals, Inc.     

The structural features of effective antagonists of the luteinizing hormone releasing hormone

Summary The structure-activity data of 6 years on 395 analogs of the luteinizing hormone releasing hormone (LHRH) have been studied to determine effective substituents for the ten positions for maximal antiovulatory activity and minimal histamine release. The numbers of substituents studied in the ten positions are as follows: (41)¹-(12)²-(12)³-(5)⁴-(47)⁵-(52)⁶-(16)⁷-(18)⁸-(4)⁹-(8)¹⁰. In position 1, DNal and DQal were effective with the former being more frequently the better substituent. DpClPhe was uniquely effective in position 2. Positions 3 and 4 are very sensitive to change. D3Pal in position 3 and Ser in position 4 of LHRH were in the best antagonists. PicLys and cPzACAla were the most successful residues in position 5 with cPzACAla being the better substituent. Position 6 was the most flexible and many substituents were effective; particularly DPicLys. Leu⁷ was most often present in the best antagonists. In position 8, Arg was effective for both antiovulatory activity and histamine release; ILys was effective for potency and lesser histamine release. Pro⁹ of LHRH was retained. DAlaNH₂ ¹⁰ was in the best antagonists.Abbreviations AABLys N -(4-acetylaminobenzoyl)lysine - AALys N -anisinoyl-lysine - AAPhe 3-(4-acetylaminophenyl)lysine - Abu 2-aminobutyric acid - ACLys N -(6-aminocaproyl)lysine - ACyh 1-aminocyclohexanecarboxylic acid - ACyp 1-aminocyclopentanecarboxylic acid - Aile alloisoleucine - AnGlu 4-(4-methoxy-phenylcarbamoyl)-2-aminobutyric acid - 2ANic 2-aminonicotinic acid - 6ANic 6-aminonicotinic acid - APic 6-aminopicolinic acid - APh 4-aminobenzoic acid - APhe 4-aminophynylalanine - APz 3-amino-2-pyrazinecarboxylic acid - Aze azetidine-2-carboxylic acid - Bim 5-benzimidazolecarboxylic acid - BzLys N -benzoyllysine - Cit citrulline - Cl₂Phe 3-(3,4-dichlorphenyl)alanine - cPzACAla cis-3-(4-pyrazinylcarbonylaminocyclohexyl)alnine - cPmACAla cis-3-[4-(4-pyrimidylcarbonyl)aminocyclohexyl]alanine - Dbf 3-(2-dibenzofuranyl)alanine - DMGLys N -(N,N-dimethylglycyl)lysine - Dpo N -(4,6-dimethyl-2-pyrimidyl)-ornithine - F₂Ala 3,3-difluoroalanine - hNal 4-(2-naphthyl)-2-aminobutyric acid - HOBLys N -(4-hydroxybenzoyl)lysine - hpClPhe 4-(4-chlorophenyl)-2-amino-butyric acid - Hse homoserine, 2-amino-4-hydroxybutanoic acid - ICapLys N -(6-isopropylaminocaproyl)lysine - ILys N -isopropyllysine - Ind indoline-2-carboxylic acid - INicLys N -isonicotinoyllysine - IOrn N -isopropylornithine - Me₃Arg N^G,N^G,N^G-trimethylarginine - Me₂Lys N ,N -dimethyllysine - MNal 3-[(6-methyl)-2-naphtyl]alanine - MNicLys N -(6-methylpicolinoyl)lysine - MPicLys N -(6-methylpicolinoyl)lysine - MOB 4-methoxybenzoyl - MpClPhe N-methyl-3-(4-chlorphenyl)lysine - MPZGlu glutamic acid,-4-methylpiperazine - Nal 3-(2-naphthyl)alanine - Nap 2-naphthoic acid - NicLys N -nicotinoyllysine - NO₂B 4-nitrobenzoyl - NO₂Phe 3-(4-nitrophenyl)alanine - oClPhe 3-(2-chlorphenyl)alanine - Opt O-phenyl-tyrosine - Pal 3-(3-pyridyl)alanine - 2Pal 3-(2-pyridyl)alanine - 2PALys N -(3-pyridylacetyl)lysine - pCapLys N -(6-picolinoylaminocaproyl)lysine - pClPhe 3-(4-chlorophenyl)alanine - pFPhe 3-(4-fluorophenyl)-alanine - Pic picolinic acid - PicLys N -picolinoyllysine - Pip piperidine-2-car-boxylic acid - PmcLys N -(4-pyrimidylcarbonyl)lysine - Ptf 3-(4-trifluromethyl phenyl)alanine - Pz pyrazinecarboxylic acid - PzAla 3-pyrazinylalanine - PzAPhe 3-(4-pyrazinylcarbonylaminophenyl)alanine - Qal 3-(3-quinolyl)alanine - Qnd-Lys N -quinaldoyllysine - Qui 3-quinolinecarboxylic acid - Qux 2-quinoxalinecarboxylic acid - Tic 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid - TinGly 2-thienylglycine - tNACAla trans-3-(4-nicotinoylaminocyclohexyl)-alanine - tPACAla trans-3-(4-picolinoylaminocyclohexyl)alanine     

Empirical testing of cryoconite granulation: Role of cyanobacteria in the formation of key biogenic structure darkening glaciers in polar regions

Cryoconite, the dark sediment on the surface of glaciers, often aggregates into oval or irregular granules serving as biogeochemical factories. They reduce a glacier's albedo, act as biodiversity hotspots by supporting aerobic and anaerobic microbial communities, constitute one of the organic matter (OM) sources on glaciers, and are a feeder for micrometazoans. Although cryoconite granules have multiple roles on glaciers, their formation is poorly understood. Cyanobacteria are ubiquitous and abundant engineers of cryoconite hole ecosystems. This study tested whether cyanobacteria may be responsible for cryoconite granulation as a sole biotic element. Incubation of Greenlandic, Svalbard, and Scandinavian cyanobacteria in different nutrient availabilities and substrata for growth (distilled water alone and water with quartz powder, furnaced cryoconite without OM, or powdered rocks from glacial catchment) revealed that cyanobacteria bind mineral particles into granules. The structures formed in the experiment resembled those commonly observed in natural cryoconite holes: they contained numerous cyanobacterial filaments protruding from aggregated mineral particles. Moreover, all examined strains were confirmed to produce extracellular polymeric substances (EPS), which suggests that cryoconite granulation is most likely due to EPS secretion by gliding cyanobacteria. In the presence of water as the only substrate for growth, cyanobacteria formed mostly carpet-like mats. Our data empirically prove that EPS-producing oscillatorialean cyanobacteria isolated from the diverse community of cryoconite microorganisms can form granules from mineral substrate and that the presence of the mineral substrate increases the probability of the formation of these important and complex biogeochemical microstructures on glaciers.     

Cell cycle and developmental control of cortical excitability in Xenopus laevis

Interest in cortical excitability—the ability of the cell cortex to generate traveling waves of protein activity—has grown considerably over the past 20 years. Attributing biological functions to cortical excitability requires an understanding of the natural behavior of excitable waves and the ability to accurately quantify wave properties. Here we have investigated and quantified the onset of cortical excitability in Xenopus laevis eggs and embryos and the changes in cortical excitability throughout early development. We found that cortical excitability begins to manifest shortly after egg activation. Further, we identified a close relationship between wave properties—such as wave frequency and amplitude—and cell cycle progression as well as cell size. Finally, we identified quantitative differences between cortical excitability in the cleavage furrow relative to nonfurrow cortical excitability and showed that these wave regimes are mutually exclusive.     

Transcriptional profiling identifies critical steps of cell cycle reprogramming necessary for Plasmodiophora brassicae‐driven gall formation in Arabidopsis

Plasmodiophora brassicae is a soil‐borne biotroph whose life cycle involves reprogramming host developmental processes leading to the formation of galls on its underground parts. Formation of such structures involves modification of the host cell cycle leading initially to hyperplasia, increasing the number of cells to be invaded, followed by overgrowth of cells colonised by the pathogen. Here we show that P. brassicae infection stimulates formation of the E2Fa/RBR1 complex and upregulation of MYB3R1, MYB3R4 and A‐ and B‐type cyclin expression. These factors were previously described as important regulators of the G2?M cell cycle checkpoint. As a consequence of this manipulation, a large population of host hypocotyl cells are delayed in cell cycle exit and maintained in the proliferative state. We also report that, during further maturation of galls, enlargement of host cells invaded by the pathogen involves endoreduplication leading to increased ploidy levels. This study characterises two aspects of the cell cycle reprogramming efforts of P. brassicae: systemic, related to the disturbance of host hypocotyl developmental programs by preventing cell cycle exit; and local, related to the stimulation of cell enlargement via increased endocycle activity.     

Screening concepts,characterization and structural analysis of microbial-derived bioactive lipopeptides: a review

Lipopeptide biosurfactants are surface active biomolecules that are produced by a variety of microorganisms. Microbial lipopeptides have gained the interest of microbiologists, chemists and biochemists for their high biodiversity as well as efficient action, low toxicity and good biodegradability in comparison to synthetic counterparts. In this report, we review methods for the production, isolation and screening, purification and structural characterization of microbial lipopeptides. Several techniques are currently available for each step, and we describe the most commonly utilized and recently developed techniques in this review. Investigations on lipopeptide biosurfactants in natural products require efficient isolation techniques for the characterization and evaluation of chemical and biological properties. A combination of chromatographic and spectroscopic techniques offer opportunities for a better characterization of lipopeptide structures, which in turn can lead to the application of lipopeptides in food, pharmaceutical, cosmetics, agricultural and bioremediation industries.     

Effects of Plectin Depletion on Keratin Network Dynamics and Organization

The keratin intermediate filament cytoskeleton protects epithelial cells against various types of stress and is involved in fundamental cellular processes such as signaling, differentiation and organelle trafficking. These functions rely on the cell type-specific arrangement and plasticity of the keratin system. It has been suggested that these properties are regulated by a complex cycle of assembly and disassembly. The exact mechanisms responsible for the underlying molecular processes, however, have not been clarified. Accumulating evidence implicates the cytolinker plectin in various aspects of the keratin cycle, i.e., by acting as a stabilizing anchor at hemidesmosomal adhesion sites and the nucleus, by affecting keratin bundling and branching and by linkage of keratins to actin filament and microtubule dynamics. In the present study we tested these hypotheses. To this end, plectin was downregulated by shRNA in vulvar carcinoma-derived A431 cells. As expected, integrin β4- and BPAG-1-positive hemidesmosomal structures were strongly reduced and cytosolic actin stress fibers were increased. In addition, integrins α3 and β1 were reduced. The experiments furthermore showed that loss of plectin led to a reduction in keratin filament branch length but did not alter overall mechanical properties as assessed by indentation analyses using atomic force microscopy and by displacement analyses of cytoplasmic superparamagnetic beads using magnetic tweezers. An increase in keratin movement was observed in plectin-depleted cells as was the case in control cells lacking hemidesmosome-like structures. Yet, keratin turnover was not significantly affected. We conclude that plectin alone is not needed for keratin assembly and disassembly and that other mechanisms exist to guarantee proper keratin cycling under steady state conditions in cultured single cells.     

NK cells and monocytes modulate primary HTLV-1 infection

We investigated the impact of monocytes, NK cells, and CD8⁺ T-cells in primary HTLV-1 infection by depleting cell subsets and exposing macaques to either HTLV-1 wild type (HTLV-1_WT) or to the HTLV-1_p12KO mutant unable to infect replete animals due to a single point mutation in orf-I that inhibits its expression. The orf-I encoded p8/p12 proteins counteract cytotoxic NK and CD8⁺ T-cells and favor viral DNA persistence in monocytes. Double NK and CD8⁺ T-cells or CD8 depletion alone accelerated seroconversion in all animals exposed to HTLV-1_WT. In contrast, HTLV-1_p12KO infectivity was fully restored only when NK cells were also depleted, demonstrating a critical role of NK cells in primary infection. Monocyte/macrophage depletion resulted in accelerated seroconversion in all animals exposed to HTLV-1_WT, but antibody titers to the virus were low and not sustained. Seroconversion did not occur in most animals exposed to HTLV-1_p12KO. In vitro experiments in human primary monocytes or THP-1 cells comparing HTLV-1_WT and HTLV-1_p12KO demonstrated that orf-I expression is associated with inhibition of inflammasome activation in primary cells, with increased CD47 “don’t-eat-me” signal surface expression in virus infected cells and decreased monocyte engulfment of infected cells. Collectively, our data demonstrate a critical role for innate NK cells in primary infection and suggest a dual role of monocytes in primary infection. On one hand, orf-I expression increases the chances of viral transmission by sparing infected cells from efferocytosis, and on the other may protect the engulfed infected cells by modulating inflammasome activation. These data also suggest that, once infection is established, the stoichiometry of orf-I expression may contribute to the chronic inflammation observed in HTLV-1 infection by modulating monocyte efferocytosis.