Myosin head orientation and mobility during isometric contraction: effects of osmotic compression.

We have correlated the mobility and the generation of force of myosin heads by applying radial compression to isometrically contracting muscle fibers. Osmotic pressure was produced by dextran T-500, and its effect on the orientation and mobility of myosin heads labeled with N-(1-oxy-2,2,5,5-tetramethyl-4-pyperidinyl)maleimide was observed by conventional and saturation-transfer electron paramagnetic resonance methods. A biphasic behavior is spectral changes coinciding with the tension dependence was observed as the fibers were compressed. At diameters above the equilibrium spacing, the large myosin head disorder characteristic during contraction in the absence of compression was largely maintained, whereas the mobility decreased threefold, from tauR approximately 25 microseconds to approximately 80-90 microseconds. The inhibition of fast microsecond motions was not accompanied by tension loss, implying that these motions are not necessary for force generation. At diameters below the equilibrium spacing, both the disorder and the mobility decreased dramatically in parallel with the tension inhibition, suggesting that slower microsecond motions and the disorder of the myosin head are necessary for muscle function.     

Sublethal malathion induced changes in the ovary of an air-breathing fish,Heteropneustes fossilis: a histological study

This paper describes effects of a sublethal (1.2 mg 1^–1) organophosphate, malathion, on the ovary of an air breathing catfish, Heteropneustes fossilis. The study focuses on microscopic changes that occur on ovigerous lamellae, oocytes at different stages of development and the nucleus of the immature oocyte. Also, change in estrogen levels in blood serum is investigated. Clumping of cytoplasm appears after 24 h of exposure to malathion. Clumping intensified after 48 h. Degeneration in the follicular cells was also observed. After 72 h exposure the number of nucleoli increased, nuclear materials shrunk, oocytes became adhered. With 96 h of exposure, nuclear materials of all the oocytes shrunk to a smaller clump. The oocytes fused together, and follicular epithelium became loose and ruptured. A few atretic oocytes were visible. Radioimmunoassay of the estrogen level in blood serum after 72 h of exposure of malathion showed a reduction in the level. This study showed that the histopathological condition of the gonad is reflected in malfunctioning of the endocrine system and hormonal disbalance.     

Interaction of gibberellic and indole-3-acetic acid on root formation in pea (Pisum sativum L.) epicotyl cuttings

Indole-3-acetic acid (IAA) strongly enhanced rooting of etiolated pea epicotyl cuttings while gibberellic acid (GA₃) enhanced rooting only slightly. The promoting effects of the hormones appeared not until 14 d after the onset of treatment. When GA₃ and IAA were applied together, the initiation of rooting started already after 6 d after onset of treatment. It is suggested that gibberellin plays an important role, in combination with auxin, in the initiation of root formation in Pisum cuttings.Abbreviations IAA Indole-3-acetic acid - GA₃ Gibberellic acid     

Technoeconomic analysis of five microalgae-to-biofuels processes of varying complexity

The economics surrounding five algae-to-fuels process scenarios were examined. The different processes modeled were as follows: an open pond producing either triacylglycerides (TAG) or free fatty acid methyl ester (FAME), a solar-lit photobioreactor producing either FAME or free fatty acids (FFA), and a light emitting diode irradiated (LED-lighted) photobioreactor producing TAG. These processes were chosen to represent both classical and esoteric approaches presented in the open literature. Viable (or suggested) processing techniques to liberate and purify (and convert) the microalgal triacylglycerides were then modeled to accompany each growth option. The investment and cost per kg of fuel or fuel precursor for each process was determined. The open pond produced TAG at ～$7.50/kg, while the process using the LED-lit photobioreactor produced TAG at ～$33/kg. The scenario containing the solar-lit photobioreactor produced FAME at ～$25/kg, while the open pond produced FAME at ～$4/kg. The scenario containing the solar-lit photobioreactor produced FFA at ～$29/kg. The open pond scenarios appear to be closest to the $1/kg pricepoint at this time, and thus are the most viable economic options. Future technological advancements that reduce the cost of bioreactor vessels, LED lighting, and solvent recovery, may reduce the oil production costs of these scenarios to a more attractive level.     

Dissociation of intracellular lysosomal rupture from the cell death caused by silica

The relationship between intracellular lysosomal rupture and cell death caused by silica was studied in P388d(1) macrophages. After 3 h of exposure to 150 μg silica in medium containing 1.8 mM Ca(2+), 60 percent of the cells were unable to exclude trypan blue. In the absence of extracellular Ca(2+), however, all of the cells remained viable. Phagocytosis of silica particles occurred to the same extent in the presence or absence of Ca(2+). The percentage of P388D(1) cells killed by silica depended on the dose and the concentration of Ca(2+) in the medium. Intracellular lyosomal rupture after exposure to silica was measured by acridine orange fluorescence or histochemical assay of horseradish peroxidase. With either assay, 60 percent of the cells exposed to 150 μg silica for 3 h in the presence of Ca(2+) showed intracellular lysosomal rupture, was not associated with measureable degradation of total DNA, RNA, protein, or phospholipids or accelerated turnover of exogenous horseradish peroxidase. Pretreatment with promethazine (20 μg/ml) protected 80 percent of P388D(1) macrophages against silica toxicity although lysosomal rupture occurred in 60-70 percent of the cells. Intracellular lysosomal rupture was prevented in 80 percent of the cells by pretreatment with indomethacin (5 x 10(-5)M), yet 40-50 percent of the cells died after 3 h of exposure to 150 μg silica in 1.8 mM extracellular Ca(2+). The calcium ionophore A23187 also caused intracellular lysosomal rupture in 90-98 percent of the cells treated for 1 h in either the presence or absence of extracellular Ca(2+). With the addition of 1.8 mM Ca(2+), 80 percent of the cells was killed after 3 h, whereas all of the cells remained viable in the absence of Ca(2+). These experiments suggest that intracellular lysosomal rupture is not causally related to the cell death cause by silica or {"type":"entrez-nucleotide","attrs":{"text":"A23187","term_id":"833253","term_text":"A23187"}}A23187. Cell death is dependent on extracellular Ca(2+) and may be mediated by an influx of these ions across the plasma membrane permeability barrier damaged directly by exposure to these toxins.     

SAXSDom: Modeling multidomain protein structures using small-angle X-ray scattering data

Many proteins are composed of several domains that pack together into a complex tertiary structure. Multidomain proteins can be challenging for protein structure modeling, particularly those for which templates can be found for individual domains but not for the entire sequence. In such cases, homology modeling can generate high quality models of the domains but not for the orientations between domains. Small-angle X-ray scattering (SAXS) reports the structural properties of entire proteins and has the potential for guiding homology modeling of multidomain proteins. In this article, we describe a novel multidomain protein assembly modeling method, SAXSDom that integrates experimental knowledge from SAXS with probabilistic Input-Output Hidden Markov model to assemble the structures of individual domains together. Four SAXS-based scoring functions were developed and tested, and the method was evaluated on multidomain proteins from two public datasets. Incorporation of SAXS information improved the accuracy of domain assembly for 40 out of 46 critical assessment of protein structure prediction multidomain protein targets and 45 out of 73 multidomain protein targets from the ab initio domain assembly dataset. The results demonstrate that SAXS data can provide useful information to improve the accuracy of domain-domain assembly. The source code and tool packages are available at https://github.com/jianlin-cheng/SAXSDom .     

DNA protective properties of vanillin against gamma-radiation under different conditions: possible mechanisms

Ionizing radiation is an important genotoxic agent. Protecting against this form of toxicant, especially by a dietary component, has several potential applications. In the present study, we have examined the ability of vanillin (4-hydroxy-3-methoxybenzaldehyde), a naturally occurring food flavouring agent, to inhibit radiation-induced DNA damage measured as strand breaks under in vitro, ex vivo and in vivo conditions besides the possible mechanisms behind the observed protection. Our study showed that there was a concentration-dependent inhibition of the disappearance of super-coiled (ccc) form of plasmid pBR322 (in vitro) upon exposure to 50 Gy of gamma-radiation. Presence of 0.5 mM vanillin has a dose-modifying factor (DMF) of 6.75 for 50% inactivation of ccc form. Exposure of human peripheral blood leucocytes (ex vivo) to gamma-radiation causes strand breaks in the cellular DNA, as assessed by comet assay. When leucocytes were exposed to 2 Gy of gamma-radiation there was an increase in parameters of comet assay such as %DNA in tail, tail length, 'tail moment' and 'Olive tail moment'. The presence of 0.5 mM vanillin during irradiation significantly reduced these parameters. Damage to DNA in mouse peripheral blood leucocytes after whole-body exposure of mice (in vivo) to gamma-radiation was studied at 1 and 2 h post-irradiation. There was recovery of DNA damage in terms of the above-mentioned parameters at 2 h post-irradiation. This was more than that observed at 1 h. The recovery was more in vanillin treated mice. Hence our studies showed that vanillin offers protection to DNA against radiation-induced damage possibly imparting a role other than modulation of DNA repair. To examine the possible mechanisms of radioprotection, in terms of radiation-derived radicals, we carried out the reaction of vanillin with ABTS*(+) radical spectrophotometrically besides with DNA peroxyl and carbonyl radicals by using pulse radiolysis. Our present investigations show that vanillin has ability to protect against DNA damage in plasmid pBR322, human and mouse peripheral blood leucocytes and splenic lymphocytes besides enhancing survival in splenic lymphocytes against gamma-radiation, and that the possible mechanism may involve scavenging of radicals generated during radiation, apart from modulation of DNA repair observed earlier.     

Exploring Lassa Virus Proteome to Design a Multi-epitope Vaccine Through Immunoinformatics and Immune Simulation Analyses

International Journal of Peptide Research and Therapeutics - Lassa virus (LASV) is responsible for a type of acute viral haemorrhagic fever referred to as Lassa fever. Lack of adequate treatment...