Anchored LH2 complexes in 2D polarization imaging.

PubMed

Tubasum, Sumera; Sakai, Shunsuke; Dewa, Takehisa; Sundström, Villy; Scheblykin, Ivan G; Nango, Mamoru; Pullerits, Tõnu

2013-09-26

Protein is a soft material with inherently large structural disorder. Consequently, the bulk spectroscopies of photosynthetic pigment protein complexes provide averaged information where many details are lost. Here we report spectroscopy of single light-harvesting complexes where fluorescence excitation and detection polarizations are both independently rotated. Two samples of peripheral antenna (LH2) complexes from Rhodopseudomonas acidophila were studied. In one, the complexes were embedded in polyvinyl alcohol (PVA) film; in the other, they were anchored on the glass surface and covered by the PVA film. LH2 contains two rings of pigment molecules-B800 and B850. The B800 excitation polarization properties of the two samples were found to be very similar, indicating that orientation statistics of LH2s are the same in these two very different preparations. At the same time, we found a significant difference in B850 emission polarization statistics. We conclude that the B850 band of the anchored sample is substantially more disordered. We argue that both B800 excitation and B850 emission polarization properties can be explained by the tilt of the anchored LH2s due to the spin-casting of the PVA film on top of the complexes and related shear forces. Due to the tilt, the orientation statistics of two samples become similar. Anchoring is expected to orient the LH2s so that B850 is closer to the substrate. Consequently, the tilt-related strain leads to larger deformation and disorder in B850 than in B800.

Static and Dynamic Disorder in Bacterial Light-Harvesting Complex LH2: A 2DES Simulation Study.

PubMed

Rancova, Olga; Abramavicius, Darius

2014-07-10

Two-dimensional coherent electronic spectroscopy (2DES) is a powerful technique in distinguishing homogeneous and inhomogeneous broadening contributions to the spectral line shapes of molecular transitions induced by environment fluctuations. Using an excitonic model of a double-ring LH2 aggregate, we perform simulations of its 2DES spectra and find that the model of a harmonic environment cannot provide a consistent set of parameters for two temperatures: 77 K and room temperature. This indicates the highly anharmonic nature of protein fluctuations for the pigments of the B850 ring. However, the fluctuations of B800 ring pigments can be assumed as harmonic in this temperature range.

Decreased expression of lysyl hydroxylase 2 (LH2) in skin fibroblasts from three Ehlers-Danlos patients does not result from mutations in either the coding or proximal promoter region of the LH2 gene.

PubMed

Walker, L C; Teebi, A S; Marini, J C; De Paepe, A; Malfait, F; Atsawasuwan, P; Yamauchi, M; Yeowell, H N

2004-12-01

The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of inherited connective tissue disorders characterized by tissue fragility, hyperelasticity of the skin and joint hypermobility. This phenotype, accompanied by kyphoscoliosis and/or ocular fragility, is present in patients with the autosomal recessive type VI form of EDS. These patients have significantly decreased levels of lysyl hydroxylase (LH) activity, due to mutations in the LH1 gene. LH hydroxylates specific lysine residues in the collagen molecule that are precursors for the formation of cross-links which provide collagen with its tensile strength. No disorder has been directly linked to decreased expression of LH2 and LH3, two other isoforms of LH. This study describes 3 patients with mixed phenotypes of EDS, who have significantly decreased mRNAs for LH2, but normal levels of LH1 and LH3 mRNAs, in their skin fibroblasts. In contrast to the effect of LH1 deficiency in EDS VI patients, the decreased expression of LH2 does not affect LH activity, bifunctional collagen cross-links (measured after reduction as dihydroxylysinonorleucine (DHLNL) and hydroxylysinonorleucine (HLNL)), or helical lysine hydroxylation in these cell lines. Sequence analysis of full length LH2 cDNAs and 1kb of the promoter region of LH2 does not show mutations that could explain the decreased expression of LH2. These results suggest that the deficiency of LH2 in these fibroblasts may be caused by changes in other factors required for the expression of LH2.

Spectral heterogeneity and carotenoid-to-bacteriochlorophyll energy transfer in LH2 light-harvesting complexes from Allochromatium vinosum.

PubMed

Magdaong, Nikki M; LaFountain, Amy M; Hacking, Kirsty; Niedzwiedzki, Dariusz M; Gibson, George N; Cogdell, Richard J; Frank, Harry A

2016-02-01

Photosynthetic organisms produce a vast array of spectral forms of antenna pigment-protein complexes to harvest solar energy and also to adapt to growth under the variable environmental conditions of light intensity, temperature, and nutrient availability. This behavior is exemplified by Allochromatium (Alc.) vinosum, a photosynthetic purple sulfur bacterium that produces different types of LH2 light-harvesting complexes in response to variations in growth conditions. In the present work, three different spectral forms of LH2 from Alc. vinosum, B800-820, B800-840, and B800-850, were isolated, purified, and examined using steady-state absorption and fluorescence spectroscopy, and ultrafast time-resolved absorption spectroscopy. The pigment composition of the LH2 complexes was analyzed by high-performance liquid chromatography, and all were found to contain five carotenoids: lycopene, anhydrorhodovibrin, spirilloxanthin, rhodopin, and rhodovibrin. Spectral reconstructions of the absorption and fluorescence excitation spectra based on the pigment composition revealed significantly more spectral heterogeneity in these systems compared to LH2 complexes isolated from other species of purple bacteria. The data also revealed the individual carotenoid-to-bacteriochlorophyll energy transfer efficiencies which were correlated with the kinetic data from the ultrafast transient absorption spectroscopic experiments. This series of LH2 complexes allows a systematic exploration of the factors that determine the spectral properties of the bound pigments and control the rate and efficiency of carotenoid-to-bacteriochlorophyll energy transfer.

Discrepancy between experimental and theoretical excitation transfer rates in LH2 bacteriochlorophyll-protein complexes of purple bacteria.

PubMed

Borisov, A Y

2008-02-01

Discrepancy is revealed between the values of excitation transfer times measured experimentally, and those calculated, for the atomic structures of B800 --> B850 bacteriochlorophylls within the LH2 light-harvesting pigment-protein complex of the purple bacterium Rhodopseudomonas acidophila. The value 2.9-3.2 ps for the B800 --> B850 excitation transfer, calculated on the basis of atomic structure of LH2, is about 4-times longer than that measured for this bacterium (0.7 ps). This discrepancy appears common in at least two purple bacteria. Possible sources responsible for this discrepancy are discussed. It may either signify some drawback/s/ in our notions about the precise in vivo structure of LH2 complexes, for example, possible changes of LH2 structure during crystallization, or it may reflect our ignorance of some mechanisms involved in excitation migration.

High Specific Power Motors in LN2 and LH2

NASA Technical Reports Server (NTRS)

Brown, Gerald V.; Jansen, Ralph H.; Trudell, Jeffrey J.

2007-01-01

A switched reluctance motor has been operated in liquid nitrogen (LN2) with a power density as high as that reported for any motor or generator. The high performance stems from the low resistivity of Cu at LN2 temperature and from the geometry of the windings, the combination of which permits steady-state rms current density up to 7000 A/cm2, about 10 times that possible in coils cooled by natural convection at room temperature. The Joule heating in the coils is conducted to the end turns for rejection to the LN2 bath. Minimal heat rejection occurs in the motor slots, preserving that region for conductor. In the end turns, the conductor layers are spaced to form a heat-exchanger-like structure that permits nucleate boiling over a large surface area. Although tests were performed in LN2 for convenience, this motor was designed as a prototype for use with liquid hydrogen (LH2) as the coolant. End-cooled coils would perform even better in LH2 because of further increases in copper electrical and thermal conductivities. Thermal analyses comparing LN2 and LH2 cooling are presented verifying that end-cooled coils in LH2 could be either much longer or could operate at higher current density without thermal runaway than in LN2.

High Specific Power Motors in LN2 and LH2

NASA Technical Reports Server (NTRS)

Brown, Gerald V.; Jansen, Ralph H.; Trudell, Jeffrey J.

2007-01-01

A switched reluctance motor has been operated in liquid nitrogen (LN2) with a power density as high as that reported for any motor or generator. The high performance stems from the low resistivity of Cu at LN2 temperature and from the geometry of the windings, the combination of which permits steady-state rms current density up to 7000 A/sq cm, about 10 times that possible in coils cooled by natural convection at room temperature. The Joule heating in the coils is conducted to the end turns for rejection to the LN2 bath. Minimal heat rejection occurs in the motor slots, preserving that region for conductor. In the end turns, the conductor layers are spaced to form a heat-exchanger-like structure that permits nucleate boiling over a large surface area. Although tests were performed in LN2 for convenience, this motor was designed as a prototype for use with liquid hydrogen (LH2) as the coolant. End-cooled coils would perform even better in LH2 because of further increases in copper electrical and thermal conductivities. Thermal analyses comparing LN2 and LH2 cooling are presented verifying that end-cooled coils in LH2 could be either much longer or could operate at higher current density without thermal runaway than in LN2.

Structural Stability of Light-harvesting Protein LH2 Adsorbed on Mesoporous Silica Supports.

PubMed

Shibuya, Yuuta; Itoh, Tetsuji; Matsuura, Shun-ichi; Yamaguchi, Akira

2015-01-01

In the present study, we examined the reversible thermal deformation of the membrane protein light-harvesting complex LH2 adsorbed on mesoporous silica (MPS) supports. The LH2 complex from Thermochromatium tepidum cells was conjugated to MPS supports with a series of pore diameter (2.4 to 10.6 nm), and absorption spectra of the resulting LH2/MPS conjugates were observed over a temperature range of 273 - 313 K in order to examine the structure of the LH2 adsorbed on the MPS support. The experimental results confirmed that a slight ellipsoidal deformation of LH2 was induced by adsorption on the MPS supports. On the other hand, the structural stability of LH2 was not perturbed by the adsorption. Since the pore diameter of MPS support did not influence the structural stability of LH2, it could be considered that the spatial confinement of LH2 in size-matches pore did not improve the structural stability of LH2.

Ground Operations Demonstration Unit for Liquid Hydrogen (GODU LH2)

NASA Technical Reports Server (NTRS)

Notardonato, William U.

2015-01-01

When the technology associated with zero loss storage and transfer is implemented, NASA can reduce the LH2 losses and procurement costs by up to 30 compared to historical Shuttle numbers. This return on investment is based on the mission manifest and commodity use. LH2 densification can provide improved launch vehicle ascent performance by minimizing the size of the LH2 tanks or storing more mass of propellant in the given tank volume.

Function of membrane protein in silica nanopores: incorporation of photosynthetic light-harvesting protein LH2 into FSM.

PubMed

Oda, Ippei; Hirata, Kotaro; Watanabe, Syoko; Shibata, Yutaka; Kajino, Tsutomu; Fukushima, Yoshiaki; Iwai, Satoshi; Itoh, Shigeru

2006-01-26

A high amount of functional membrane protein complex was introduced into a folded-sheet silica mesoporous material (FSM) that has nanometer-size pores of honeycomb-like hexagonal cylindrical structure inside. The photosynthetic light-harvesting complex LH2, which is a typical membrane protein, has a cylindrical structure of 7.3 nm diameter and contains 27 bacteriochlorophyll a and nine carotenoid molecules. The complex captures light energy in the anoxygenic thermophilic purple photosynthetic bacterium Thermochromatium tepidum. The amount of LH2 adsorbed to FSM was determined optically and by the adsorption isotherms of N2. The FSM compounds with internal pore diameters of 7.9 and 2.7 nm adsorbed LH2 at 1.11 and 0.24 mg/mg FSM, respectively, suggesting the high specific affinity of LH2 to the interior of the hydrophobic nanopores with a diameter of 7.9 nm. The LH2 adsorbed to FSM showed almost intact absorption bands of bacteriochlorophylls, and was fully active in the capture and transfer of excitation energy. The LH2 complex inside the FSM showed increased heat stability of the exciton-type absorption band of bacteriochlorophylls (B850), suggesting higher circular symmetry. The environment inside the hydrophobic silica nanopores can be a new matrix for the membrane proteins to reveal their functions. The silica-membrane protein adduct will be useful for the construction of new probes and reaction systems.

Crystallization and preliminary X-ray diffraction analysis of the peripheral light-harvesting complex LH2 from Marichromatium purpuratum.

PubMed

Cranston, Laura J; Roszak, Aleksander W; Cogdell, Richard J

2014-06-01

LH2 from the purple photosynthetic bacterium Marichromatium (formerly known as Chromatium) purpuratum is an integral membrane pigment-protein complex that is involved in harvesting light energy and transferring it to the LH1-RC `core' complex. The purified LH2 complex was crystallized using the sitting-drop vapour-diffusion method at 294 K. The crystals diffracted to a resolution of 6 Å using synchrotron radiation and belonged to the tetragonal space group I4, with unit-cell parameters a=b=109.36, c=80.45 Å. The data appeared to be twinned, producing apparent diffraction symmetry I422. The tetragonal symmetry of the unit cell and diffraction for the crystals of the LH2 complex from this species reveal that this complex is an octamer.

Crystallization and preliminary X-ray diffraction analysis of the peripheral light-harvesting complex LH2 from Marichromatium purpuratum

PubMed Central

Cranston, Laura J.; Roszak, Aleksander W.; Cogdell, Richard J.

2014-01-01

LH2 from the purple photosynthetic bacterium Marichromatium (formerly known as Chromatium) purpuratum is an integral membrane pigment–protein complex that is involved in harvesting light energy and transferring it to the LH1–RC ‘core’ complex. The purified LH2 complex was crystallized using the sitting-drop vapour-diffusion method at 294 K. The crystals diffracted to a resolution of 6 Å using synchrotron radiation and belonged to the tetragonal space group I4, with unit-cell parameters a = b = 109.36, c = 80.45 Å. The data appeared to be twinned, producing apparent diffraction symmetry I422. The tetragonal symmetry of the unit cell and diffraction for the crystals of the LH2 complex from this species reveal that this complex is an octamer. PMID:24915099

Monomeric RC-LH1 core complexes retard LH2 assembly and intracytoplasmic membrane formation in PufX-minus mutants of Rhodobacter sphaeroides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, Peter G.; Mothersole, David J.; Ng, Irene W.

2011-01-01

In the model photosynthetic bacterium Rhodobacter sphaeroides domains of light-harvesting 2 (LH2) complexes surround and interconnect dimeric reaction centre–light-harvesting 1–PufX (RC–LH1–PufX) ‘core’ complexes, forming extensive networks for energy transfer and trapping. These complexes are housed in spherical intracytoplasmic membranes (ICMs), which are assembled in a stepwise process where biosynthesis of core complexes tends to dominate the early stages of membrane invagination. The kinetics of LH2 assembly were measured in PufX mutants that assemble monomeric core complexes, as a consequence of either a twelve-residue N-terminal truncation of PufX (PufXΔ12) or the complete removal of PufX (PufX -). Lower rates of LH2more » assembly and retarded maturation of membrane invagination were observed for the larger and less curved ICM from the PufX - mutant, consistent with the proposition that local membrane curvature, initiated by arrays of bent RC–LH1–PufX dimers, creates a favourable environment for stable assembly of LH2 complexes. Transmission electron microscopy and high-resolution atomic force microscopy were used to examine ICM morphology and membrane protein organisation in these mutants. Some partitioning of core and LH2 complexes was observed in PufX - membranes, resulting in locally ordered clusters of monomeric RC–LH1 complexes. The distribution of core and LH2 complexes in the three types of membrane examined is consistent with previous models of membrane curvature and domain formation (Frese et al., 2008), which demonstrated that a combination of crowding and asymmetries in sizes and shapes of membrane protein complexes drives membrane organisation.« less

Monomeric RC-LH1 core complexes retard LH2 assembly and intracytoplasmic membrane formation in PufX-minus mutants of Rhodobacter sphaeroides.

PubMed

Adams, Peter G; Mothersole, David J; Ng, Irene W; Olsen, John D; Hunter, C Neil

2011-09-01

In the model photosynthetic bacterium Rhodobacter sphaeroides domains of light-harvesting 2 (LH2) complexes surround and interconnect dimeric reaction centre-light-harvesting 1-PufX (RC-LH1-PufX) 'core' complexes, forming extensive networks for energy transfer and trapping. These complexes are housed in spherical intracytoplasmic membranes (ICMs), which are assembled in a stepwise process where biosynthesis of core complexes tends to dominate the early stages of membrane invagination. The kinetics of LH2 assembly were measured in PufX mutants that assemble monomeric core complexes, as a consequence of either a twelve-residue N-terminal truncation of PufX (PufXΔ12) or the complete removal of PufX (PufX(-)). Lower rates of LH2 assembly and retarded maturation of membrane invagination were observed for the larger and less curved ICM from the PufX(-) mutant, consistent with the proposition that local membrane curvature, initiated by arrays of bent RC-LH1-PufX dimers, creates a favourable environment for stable assembly of LH2 complexes. Transmission electron microscopy and high-resolution atomic force microscopy were used to examine ICM morphology and membrane protein organisation in these mutants. Some partitioning of core and LH2 complexes was observed in PufX(-) membranes, resulting in locally ordered clusters of monomeric RC-LH1 complexes. The distribution of core and LH2 complexes in the three types of membrane examined is consistent with previous models of membrane curvature and domain formation (Frese et al., 2008), which demonstrated that a combination of crowding and asymmetries in sizes and shapes of membrane protein complexes drives membrane organisation. 2011 Elsevier B.V. All rights reserved.

Ground-State Electronic Structure of RC-LH1 and LH2 Pigment Assemblies of Purple Bacteria via the EBF-MO Method.

PubMed

Shrestha, Kushal; Jakubikova, Elena

2015-08-20

Light-harvesting antennas are protein-pigment complexes that play a crucial role in natural photosynthesis. The antenna complexes absorb light and transfer energy to photosynthetic reaction centers where charge separation occurs. This work focuses on computational studies of the electronic structure of the pigment networks of light-harvesting complex I (LH1), LH1 with the reaction center (RC-LH1), and light-harvesting complex II (LH2) found in purple bacteria. As the pigment networks of LH1, RC-LH1, and LH2 contain thousands of atoms, conventional density functional theory (DFT) and ab initio calculations of these systems are not computationally feasible. Therefore, we utilize DFT in conjunction with the energy-based fragmentation with molecular orbitals method and a semiempirical approach employing the extended Hückel model Hamiltonian to determine the electronic properties of these pigment assemblies. Our calculations provide a deeper understanding of the electronic structure of natural light-harvesting complexes, especially their pigment networks, which could assist in rational design of artificial photosynthetic devices.

Cryogenic foam insulation for LH2 fueled subsonic transports

NASA Technical Reports Server (NTRS)

Sharpe, E. L.; Helenbrook, R. G.

1978-01-01

Shortages of petroleum-based aircraft fuels are foreseen before the end of the century. To cope with such shortages, NASA is developing a commercial aircraft which can operate on liquid hydrogen. Various foam insulators for LH2 storage are considered in terms of thermal performance and service life. Of the cryogenic foams considered (plain foam, foam with flame retardants and fiberglass reinforcement, and foam with vapor barriers), polyurethane foams were found to be the best. Tests consisted of heating a 5 cm layer of insulation around an aluminum tank containing LH2 to 316 K, and then cooling it to 266 K, while the inner surface was maintained at LH2 temperature (20 K).

[Influence of LDAO on the conformation and release of bacteriochlorophyll of peripheral light-harvesting complex (LH2) from Rhodobacter azotoformans].

PubMed

Zhao, Gen-gui; Dong, Yan-min; Yang, Su-ping; Jiao, Nian-zhi; Qu, Yin-bo

2010-10-01

The aim of this study is to reveal the interaction relationships between lauryl dimethylamine N-oxide (LDAO) and peripheral light-harvesting complex (LH2) as well as the influence of LDAO on structure and function of LH2. In the present work, the effects of LDAO on the conformation and release processes of bacteriochlorophyll (BChl) of LH2 when incubated under different temperature and pH in the presence and absence of LDAO were investigated by spectroscopy. The results indicated that (1) the presence of LDAO resulted in alterations in the conformation, alpha-helix content, and spectra of Tyr and B850 band of LH2 at room temperature and pH 8.0. Moreover, energy transfer efficiency of LH2 was enhanced markedly in the presence of LDAO. (2) At 60 degrees C, both the B800 and B850 band of LH2 were released and transited into free BChl at pH 8.0. However, the release rates of bacteriochlorophylls of B800 and B850 band from LH2 were slowed down and the release processes were changed when incubated in the presence of LDAO. Hence, the stability of LH2 was improved in the presence of LDAO. (3) The accelerated release processes of bacteriochlorophylls of B800 and B850 band of LH2 were induced to transform into bacteriopheophytin (BPhe) and free BChl by LDAO in strong acid and strong alkalic solution at room temperature. However, the kinetic patterns of the B800 and B850 band were remarkably different. The release and self-assemble processes of B850 in LH2 were observed in strong acid solution without LDAO. Therefore, the different release behaviors of B800 and B850 of LH2 are induced by LDAO under different extreme environmental conditions.

[Construction and Characterization of B850-Only LH2 Energy Transfer System in Purple Bacteria].

PubMed

Li, Kai; Zhao, Chun-gui; Yue, Hui-ying; Yang, Su-ping; Qu, Yin-bo; Jiao, Nian-zhi

2015-04-01

To seek microscopic molecular mechanism of energy transfer and complex reconstitution in the photosynthesis, the conditions for construction of B850-only peripheral light-harvesting complex (LH2) and their properties were investigated using absorption, fluorescence spectroscopy, molecular sieve chromatography, ultrafiltration and sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) from the purple bacteria. The results indicated that bacteriochlorophylls (BChl) of B800 incubated in 10 mmo · L(-1) Tris-HCl (pH 8.0) buffer are selectively released from their binding sites of LH2 of Rhodobacter azotoformans (A-LH2) by 0.08% (W/V) SDS. B850-only A-LH2 was constructed after removing free BChl mixing with 10% methyl alcohol by ultrafiltration. B850 BChl was released after A-LH2 was incubated for 240 min in dark at room temperature (RT). While BChl of B800 incubated in pH 1.9 buffer were selectively released from their binding sites of LH2 of Rhodopseudomonas palustris (P-LH2). The authors acquired two components using molecular sieve chromatography. Free BChl of one component was not removed and self-assembled to P-LH2. The other removed free BChl and B850-only P-LH2 was constructed. B850 unchanged after P-LH2 was incubated. P-LH2 α and β subunits have different molecular weights, but those of A-LH2 are in the contrary. It is concluded that B850-only P-LH2 is more stable than A-LH2. The enigmatic split of the B800 absorption band was not observed in these LH2, but we acquired two kinds of B800-released LH2 from Rhodopseudomonas palustris. The authors' results may provide a new light to separate homogeneous Apoprotein LH2.

Heterogeneity of carotenoid content and composition in LH2 of the purple sulphur bacterium Allochromatium minutissimum grown under carotenoid-biosynthesis inhibition.

PubMed

Makhneva, Zoya; Bolshakov, Maksim; Moskalenko, Andrey

2008-01-01

The effects brought about by growing Allochromatium (Alc.) minutissimum in the presence of different concentrations of the carotenoid (Car) biosynthetic inhibitor diphenylamine (DPA) have been investigated. A decrease of Car content (from approximately 70% to >5%) in the membranes was accompanied by an increase of the percentage of (immature) Cars with reduced numbers of conjugated C=C bonds (from neurosporene to phytoene). Based on the obtained results and the analysis of literature data, the conclusion is reached that accumulation of phytoene during inhibition did not occur. Surprisingly, DPA inhibited phytoene synthase instead of phytoene desaturase as generally assumed. The distribution of Cars in peripheral antenna (LH2) complexes and their effect on the stability of LH2 has been investigated using absorption spectroscopy and HPLC analysis. Heterogeneity of Car composition and contents in the LH2 pool is revealed. The Car contents in LH2 varied widely from control levels to complete absence. According to common view, the assembly of LH2 occurs only in the presence of Cars. Here, we show that the LH2 can be assembled without any Cars. The presence of Cars, however, is important for structural stability of LH2 complexes.

Molecular Level Design Principle behind Optimal Sizes of Photosynthetic LH2 Complex: Taming Disorder through Cooperation of Hydrogen Bonding and Quantum Delocalization.

PubMed

Jang, Seogjoo; Rivera, Eva; Montemayor, Daniel

2015-03-19

The light harvesting 2 (LH2) antenna complex from purple photosynthetic bacteria is an efficient natural excitation energy carrier with well-known symmetric structure, but the molecular level design principle governing its structure-function relationship is unknown. Our all-atomistic simulations of nonnatural analogues of LH2 as well as those of a natural LH2 suggest that nonnatural sizes of LH2-like complexes could be built. However, stable and consistent hydrogen bonding (HB) between bacteriochlorophyll and the protein is shown to be possible only near naturally occurring sizes, leading to significantly smaller disorder than for nonnatural ones. Extensive quantum calculations of intercomplex exciton transfer dynamics, sampled for a large set of disorder, reveal that taming the negative effect of disorder through a reliable HB as well as quantum delocalization of the exciton is a critical mechanism that makes LH2 highly functional, which also explains why the natural sizes of LH2 are indeed optimal.

Direct Observation of Energy Detrapping in LH1-RC Complex by Two-Dimensional Electronic Spectroscopy.

PubMed

Ma, Fei; Yu, Long-Jiang; Hendrikx, Ruud; Wang-Otomo, Zheng-Yu; van Grondelle, Rienk

2017-01-18

The purple bacterial core light harvesting antenna-reaction center (LH1-RC) complex is the simplest system able to achieve the entire primary function of photosynthesis. During the past decade, a variety of photosynthetic proteins were studied by a powerful technique, two-dimensional electronic spectroscopy (2DES). However, little attention has been paid to LH1-RC, although its reversible uphill energy transfer, trapping, and backward detrapping processes, represent a crucial step in the early photosynthetic reaction dynamics. Thus, in this work, we employed 2DES to study two LH1-RC complexes of Thermochromatium (Tch.) tepidum. By direct observation of detrapping, the complex reversible process was clearly identified and an overall scheme of the excitation evolution in LH1-RC was obtained.

LO2/LH2 propulsion for outer planet orbiter spacecraft

NASA Technical Reports Server (NTRS)

Garrison, P. W.; Sigurdson, K. B.

1983-01-01

Galileo class orbiter missions (750-1500 kg) to the outer planets require a large postinjection delta-V for improved propulsion performance. The present investigation shows that a pump-fed low thrust LO2/LH2 propulsion system can provide a significantly larger net on-orbit mass for a given delta-V than a state-of-the-art earth storable, N2O4/monomethylhydrazine pressure-fed propulsion system. A description is given of a conceptual design for a LO2/LH2 pump-fed propulsion system developed for a Galileo class mission to the outer planets. Attention is given to spacecraft configuration, details regarding the propulsion system, the thermal control of the cryogenic propellants, and aspects of mission performance.

Direct Visualization of Exciton Reequilibration in the LH1 and LH2 Complexes of Rhodobacter sphaeroides by Multipulse Spectroscopy

PubMed Central

Cohen Stuart, Thomas A.; Vengris, Mikas; Novoderezhkin, Vladimir I.; Cogdell, Richard J.; Hunter, C. Neil; van Grondelle, Rienk

2011-01-01

The dynamics of the excited states of the light-harvesting complexes LH1 and LH2 of Rhodobacter sphaeroides are governed, mainly, by the excitonic nature of these ring-systems. In a pump-dump-probe experiment, the first pulse promotes LH1 or LH2 to its excited state and the second pulse dumps a portion of the excited state. By selective dumping, we can disentangle the dynamics normally hidden in the excited-state manifold. We find that by using this multiple-excitation technique we can visualize a 400-fs reequilibration reflecting relaxation between the two lowest exciton states that cannot be directly explored by conventional pump-probe. An oscillatory feature is observed within the exciton reequilibration, which is attributed to a coherent motion of a vibrational wavepacket with a period of ∼150 fs. Our disordered exciton model allows a quantitative interpretation of the observed reequilibration processes occurring in these antennas. PMID:21539791

Direct visualization of exciton reequilibration in the LH1 and LH2 complexes of Rhodobacter sphaeroides by multipulse spectroscopy.

PubMed

Cohen Stuart, Thomas A; Vengris, Mikas; Novoderezhkin, Vladimir I; Cogdell, Richard J; Hunter, C Neil; van Grondelle, Rienk

2011-05-04

The dynamics of the excited states of the light-harvesting complexes LH1 and LH2 of Rhodobacter sphaeroides are governed, mainly, by the excitonic nature of these ring-systems. In a pump-dump-probe experiment, the first pulse promotes LH1 or LH2 to its excited state and the second pulse dumps a portion of the excited state. By selective dumping, we can disentangle the dynamics normally hidden in the excited-state manifold. We find that by using this multiple-excitation technique we can visualize a 400-fs reequilibration reflecting relaxation between the two lowest exciton states that cannot be directly explored by conventional pump-probe. An oscillatory feature is observed within the exciton reequilibration, which is attributed to a coherent motion of a vibrational wavepacket with a period of ∼150 fs. Our disordered exciton model allows a quantitative interpretation of the observed reequilibration processes occurring in these antennas. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Spectroscopic studies of two spectral variants of light-harvesting complex 2 (LH2) from the photosynthetic purple sulfur bacterium Allochromatium vinosum.

PubMed

Niedzwiedzki, Dariusz M; Bina, David; Picken, Nichola; Honkanen, Suvi; Blankenship, Robert E; Holten, Dewey; Cogdell, Richard J

2012-09-01

Two spectral forms of the peripheral light-harvesting complex (LH2) from the purple sulfur photosynthetic bacterium Allochromatium vinosum were purified and their photophysical properties characterized. The complexes contain bacteriochlorophyll a (BChl a) and multiple species of carotenoids. The composition of carotenoids depends on the light conditions applied during growth of the cultures. In addition, LH2 grown under high light has a noticeable split of the B800 absorption band. The influence of the change of carotenoid distribution as well as the spectral change of the excitonic absorption of the bacteriochlorophylls on the light-harvesting ability was studied using steady-state absorption, fluorescence and femtosecond time-resolved absorption at 77K. The results demonstrate that the change of the distribution of the carotenoids when cells were grown at low light adapts the absorptive properties of the complex to the light conditions and maintains maximum photon-capture performance. In addition, an explanation for the origin of the enigmatic split of the B800 absorption band is provided. This spectral splitting is also observed in LH2 complexes from other photosynthetic sulfur purple bacterial species. According to results obtained from transient absorption spectroscopy, the B800 band split originates from two spectral forms of the associated BChl a monomeric molecules bound within the same complex. Copyright © 2012 Elsevier B.V. All rights reserved.

Fracture Mechanics Analysis of LH2 Feed Line Flow Liners

NASA Technical Reports Server (NTRS)

James, Mark A.; Dawicke, David S.; Brzowski, Matthew B.; Raju, Ivatury S.; Elliott, Kenny B.; Harris, Charles E.

2006-01-01

Inspections of the Space Shuttle Main Engine revealed fatigue cracks growing from slots in the flow liner of the liquid hydrogen (LH2) feed lines. During flight, the flow liners experience complex loading induced by flow of LH2 and the resonance characteristics of the structure. The flow liners are made of Inconel 718 and had previously not been considered a fracture critical component. However, fatigue failure of a flow liner could have catastrophic effect on the Shuttle engines. A fracture mechanics study was performed to determine if a damage tolerance approach to life management was possible and to determine the sensitivity to the load spectra, material properties, and crack size. The load spectra were derived separately from ground tests and material properties were obtained from coupon tests. The stress-intensity factors for the fatigue cracks were determined from a shell-dynamics approach that simulated the dominant resonant frequencies. Life predictions were obtained using the NASGRO life prediction code. The results indicated that adequate life could not be demonstrated for initial crack lengths of the size that could be detected by traditional NDE techniques.

Orbiter LH2 Feedline Flowliner Cracking Problem. Version 1.0

NASA Technical Reports Server (NTRS)

Harris, Charles E.; Cragg, Clinton H.; Raju, Ivatury S.; Elliot, Kenny B.; Madaras, Eric I.; Piascik, Robert S.; Halford, Gary R.; Bonacuse, Peter J.; Sutliff, Daniel L.; Bakhle, Milind A.

2005-01-01

In May of 2002, three cracks were found in the downstream flowliner at the gimbal joint in the LH2 feedline at the interface with the Low Pressure Fuel Turbopump (LPFP) of Space Shuttle Main Engine (SSME) #1 of Orbiter OV-104. Subsequent inspections of the feedline flowliners in the other orbiters revealed the existence of 8 additional cracks. No cracks were found in the LO2 feedline flowliners. A solution to the cracking problem was developed and implemented on all orbiters. The solution included weld repair of all detectable cracks and the polishing of all slot edges to remove manufacturing discrepancies that could initiate new cracks. Using the results of a fracture mechanics analysis with a scatter factor of 4 on the predicted fatigue life, the orbiters were cleared for return to flight with a one-flight rationale requiring inspections after each flight. OV-104 flew mission STS-112 and OV-105 flew mission STS-113. The post-flight inspections did not find any cracks in the repaired flowliners. At the request of the Orbiter Program, the NESC conducted an assessment of the Orbiter LH2 Feedline Flowliner cracking problem with a team of subject matter experts from throughout NASA.

Ultrafast time-resolved carotenoid to-bacteriochlorophyll energy transfer in LH2 complexes from photosynthetic bacteria.

PubMed

Cong, Hong; Niedzwiedzki, Dariusz M; Gibson, George N; LaFountain, Amy M; Kelsh, Rhiannon M; Gardiner, Alastair T; Cogdell, Richard J; Frank, Harry A

2008-08-28

Steady-state and ultrafast time-resolved optical spectroscopic investigations have been carried out at 293 and 10 K on LH2 pigment-protein complexes isolated from three different strains of photosynthetic bacteria: Rhodobacter (Rb.) sphaeroides G1C, Rb. sphaeroides 2.4.1 (anaerobically and aerobically grown), and Rps. acidophila 10050. The LH2 complexes obtained from these strains contain the carotenoids, neurosporene, spheroidene, spheroidenone, and rhodopin glucoside, respectively. These molecules have a systematically increasing number of pi-electron conjugated carbon-carbon double bonds. Steady-state absorption and fluorescence excitation experiments have revealed that the total efficiency of energy transfer from the carotenoids to bacteriochlorophyll is independent of temperature and nearly constant at approximately 90% for the LH2 complexes containing neurosporene, spheroidene, spheroidenone, but drops to approximately 53% for the complex containing rhodopin glucoside. Ultrafast transient absorption spectra in the near-infrared (NIR) region of the purified carotenoids in solution have revealed the energies of the S1 (2(1)Ag-)-->S2 (1(1)Bu+) excited-state transitions which, when subtracted from the energies of the S0 (1(1)Ag-)-->S2 (1(1)Bu+) transitions determined by steady-state absorption measurements, give precise values for the positions of the S1 (2(1)Ag-) states of the carotenoids. Global fitting of the ultrafast spectral and temporal data sets have revealed the dynamics of the pathways of de-excitation of the carotenoid excited states. The pathways include energy transfer to bacteriochlorophyll, population of the so-called S* state of the carotenoids, and formation of carotenoid radical cations (Car*+). The investigation has found that excitation energy transfer to bacteriochlorophyll is partitioned through the S1 (1(1)Ag-), S2 (1(1)Bu+), and S* states of the different carotenoids to varying degrees. This is understood through a consideration of the

Kisspeptin and LH pulsatile temporal coupling in PCOS patients.

PubMed

Katulski, Krzysztof; Podfigurna, Agnieszka; Czyzyk, Adam; Meczekalski, Blazej; Genazzani, Alessandro D

2018-05-04

To evaluate the temporal coupling between spontaneous kisspeptin and luteinizing hormone (LH) pulsatile releases in polycystic ovary syndrome (PCOS) patients. We examined 71 patients diagnosed with PCOS. A 2 h pulsatility study was performed to evaluate serum kisspeptin and LH pulse frequency and concentration, sampled every 10 min; baseline follicle-stimulating hormone (FSH), estradiol (E2), prolactin (PRL), cortisol, 17-hydroksy-progesterone (17OHP), testosterone (T), free testosterone index (FTI, and insulin levels were also measured. Detect and Specific Concordance (SC) algorithms were used to evaluate the temporal coupling associations between spontaneous episodic secretion of kisspeptin and LH. All PCOS patients demonstrated LH and kisspeptin pulsatile secretions. When the SC index was calculated across the sample of PCOS patients (n = 71), no temporal coupling was observed between kisspeptin and LH pulses. When PCOS patients were subdivided according to their menstrual cyclicity, oligomenorrheic patients demonstrated elevated kisspeptin pulse frequency. Additionally, the SC index reveled a temporal coupling between kisspeptin and LH secretory peaks only in eumenorrheic patients (n = 30, intermenstrual interval < 45 days). Oligomenorrheic PCOS patients (intermenstrual interval > 45 days) did not demonstrate temporal coupling between kisspeptin and LH secretory peaks. The study of the endogenous kisspeptin and LH pulsatile release revealed the temporal coupling of kisspeptin with LH secretory pulses only in eumenorrheic. This data supports the hypothesis that neuroendocrine impairments in PCOS affect the coupling of kisspeptin with LH pulses and potentially worsen as the disease progresses, becoming unequivocally evident in oligomenorrheic PCOS patients.

Distribution of rhodopin and spirilloxanthin between LH1 and LH2 complexes when incorporating carotenoid mixture into the membrane of purple sulfur bacterium Allochromatium minutissimum in vitro.

PubMed

Bolshakov, M A; Ashikhmin, A A; Makhneva, Z K; Moskalenko, A A

2016-11-01

Carotenoid mixture enriched by rhodopin and spirilloxanthin was incorporated in LH2 and LH1 complexes from Allochromatium (Alc.) minutissimum in vitro. The maximum incorporating level was ~95%. Rhodopin (56.4%) and spirilloxanthin (13.8%) were incorporated into the LH1 complex, in contrast to the control complex, which contained primarily spirilloxanthin (66.8%). After incorporating, the LH2 complex contained rhodopin (66.7%) and didehydrorhodopin (14.6%), which was close to their content in the control (67.4 and 20.5%, respectively). Thus, it was shown that carotenoids from the total pool are not selectively incorporated into LH2 and LH1 complexes in vitro in the proportion corresponding to the carotenoid content in the complexes in vivo.

Risk Assessment and Scaling for the SLS LH2 ET

NASA Technical Reports Server (NTRS)

Hafiychuk, Halyna; Ponizovskaya-Devine, Ekaterina; Luchinsky, Dmitry; Khasin, Michael; Osipov, Viatcheslav V.; Smelyanskiy, Vadim N.

2012-01-01

In this report the main physics processes in LH2 tank during prepress and rocket flight are studied. The goal of this investigation is to analyze possible hazards and to make risk assessment in proposed LH2 tank designs for SLS with 5 engines (the situation with 4 engines is less critical). For analysis we use the multinode model (MNM) developed by us and presented in a separate report and also 3D ANSYS simulations. We carry out simulation and theoretical analysis the physics processes such as (i) accumulation of bubbles in LH2 during replenish stage and their collapsing in the liquid during the prepress; (ii) condensation-evaporation at the liquid-vapor interface and tank wall, (iv) heating the liquid near the interface and wall due to condensation and environment heat, (v) injection of hot He during prepress and of hot GH2 during flight, (vi) mixing and cooling of the injected gases due to heat transfer between the gases, liquid and the tank wall. We analyze the effects of these physical processes on the thermo- and fluid gas dynamics in the ullage and on the stratification of temperature in the liquid and assess the associated hazards. A special emphasize is put on the scaling predictions for the larger SLS LH2 tank.

Radioimmunoassay of LH (in Japanese)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Motohashi, T.; Yogo, I.

The methods of isolation of binding free hormones (B/F), the double antibody method, adsorption method (dextran charcoal method), and precipitation method (dioxane method) were compared for the RIA of LH in the blood. Comparison of the standard curves revealed no difference among the three methods within measurable limits. The dextran charcoal method, a rapid quantitative determination, tended to be inferior in the variation and reproducibility of intraassay. The dioxane method was shown to be an excellent method in the convenience of procedures, precision, and reproducibility, except for the disadvantage of using an antigen-antibody system which is heterologous to LH. Whenmore » changes in the LH values during menstrual cycles in normal Mature women were examined, a large increase was observed in the phase of ovulation. In case of the administration of Enavid, an oral contraceptive, large fluctuations occurred in the LH value, indicating that ovulation was accompanied by an increase in LR. Changes in the blood LH before, during, and after the administration of Clomid, aimed at ovulation induction, were observed. (Japan)« less

Conformational Complexity in the LH2 Antenna of the Purple Sulfur Bacterium Allochromatium vinosum Revealed by Hole-Burning Spectroscopy.

PubMed

Kell, Adam; Jassas, Mahboobe; Acharya, Khem; Hacking, Kirsty; Cogdell, Richard J; Jankowiak, Ryszard

2017-06-15

This work discusses the protein conformational complexity of the B800-850 LH2 complexes from the purple sulfur bacterium Allochromatium vinosum, focusing on the spectral characteristics of the B850 chromophores. Low-temperature B850 absorption and the split B800 band shift blue and red, respectively, at elevated temperatures, revealing isosbestic points. The latter indicates the presence of two (unresolved) conformations of B850 bacteriochlorophylls (BChls), referred to as conformations 1 and 2, and two conformations of B800 BChls, denoted as B800 R and B800 B . The energy differences between average site energies of conformations 1 and 2, and B800 R and B800 B are similar (∼200 cm -1 ), suggesting weak and strong hydrogen bonds linking two major subpopulations of BChls and the protein scaffolding. Although conformations 1 and 2 of the B850 chromophores, and B800 R and B800 B , exist in the ground state, selective excitation leads to 1 → 2 and B800 R → B800 B phototransformations. Different static inhomogeneous broadening is revealed for the lowest energy exciton states of B850 (fwhm ∼195 cm -1 ) and B800 R (fwhm ∼140 cm -1 ). To describe the 5 K absorption spectrum and the above-mentioned conformations, we employ an exciton model with dichotomous protein conformation disorder. We show that both experimental data and the modeling study support a two-site model with strongly and weakly hydrogen-bonded B850 and B800 BChls, which under illumination undergo conformational changes, most likely caused by proton dynamics.

Characterisation of the LH2 spectral variants produced by the photosynthetic purple sulphur bacterium Allochromatium vinosum.

PubMed

Carey, Anne-Marie; Hacking, Kirsty; Picken, Nichola; Honkanen, Suvi; Kelly, Sharon; Niedzwiedzki, Dariusz M; Blankenship, Robert E; Shimizu, Yuuki; Wang-Otomo, Zheng-Yu; Cogdell, Richard J

2014-11-01

This study systematically investigated the different types of LH2 produced by Allochromatium (Alc.) vinosum, a photosynthetic purple sulphur bacterium, in response to variations in growth conditions. Three different spectral forms of LH2 were isolated and purified, the B800-820, B800-840 and B800-850 LH2 types, all of which exhibit an unusual split 800 peak in their low temperature absorption spectra. However, it is likely that more forms are also present. Relatively more B800-820 and B800-840 are produced under low light conditions, while relatively more B800-850 is produced under high light conditions. Polypeptide compositions of the three different LH2 types were determined by a combination of HPLC and TOF/MS. The B800-820, B800-840 and B800-850 LH2 types all have a heterogeneous polypeptide composition, containing multiple types of both α and β polypeptides, and differ in their precise polypeptide composition. They all have a mixed carotenoid composition, containing carotenoids of the spirilloxanthin series. In all cases the most abundant carotenoid is rhodopin; however, there is a shift towards carotenoids with a higher conjugation number in LH2 complexes produced under low light conditions. CD spectroscopy, together with the polypeptide analysis, demonstrates that these Alc. vinosum LH2 complexes are more closely related to the LH2 complex from Phs. molischianum than they are to the LH2 complexes from Rps. acidophila. Copyright © 2014. Published by Elsevier B.V.

Empirical Profiling of Cold Hydrogen Plumes Formed from Venting Of LH2 Storage Vessels: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buttner, William J; Rivkin, Carl H; Schmidt, Kara

Liquid hydrogen (LH2) storage is a viable approach to assuring sufficient hydrogen capacity at commercial fuelling stations. Presently, LH2 is produced at remote facilities and then transported to the end-use site by road vehicles (i.e., LH2 tanker trucks). Venting of hydrogen to depressurize the transport storage tank is a routine part of the LH2 delivery process. The behaviour of cold hydrogen plumes has not been well-characterized because empirical field data is essentially non-existent. The NFPA 2 Hydrogen Storage Safety Task Group, which consists of hydrogen producers, safety experts, and CFD modellers, has identified the lack of understanding of hydrogen dispersionmore » during LH2 venting of storage vessel as a critical gap for establishing safety distances at LH2 facilities, especially commercial hydrogen fuelling stations. To address this need, the NREL sensor laboratory, in collaboration with the NFPA 2 Safety Task Group developed the Cold Hydrogen Plume Analyzer to empirically characterize the hydrogen plume formed during LH2 storage tank venting. A prototype Analyzer was developed and field-deployed at an actual LH2 venting operation with critical findings that included: - H2 being detected as much as 2 m lower than the release point, which is not predicted by existing models - A small and inconsistent correlation between oxygen depletion and the hydrogen concentration - A negligible to non-existent correlation between in-situ temperature and the hydrogen concentration The Analyzer is currently being upgraded for enhanced metrological capabilities including improved real-time spatial and temporal profiling of the plume and tracking of prevailing weather conditions. Additional deployments are planned to monitor plume behaviour under different wind, humidity, and temperatures. This data will be shared with the NFPA 2 Safety Task Group and ultimately will be used support theoretical models and code requirements prescribed in NFPA 2.« less

Maternal postpartum learned helplessness (LH) affects maternal care by dams and responses to the LH test in adolescent offspring.

PubMed

Kurata, Akiko; Morinobu, Shigeru; Fuchikami, Manabu; Yamamoto, Shigeto; Yamawaki, Shigeto

2009-06-01

It is known that the early environment affects the mental development of rodent and human offspring. However, it is not known specifically whether a postpartum depressive state influences the depressive state in offspring. Using learned helplessness (LH) in rats as an animal model of depression, we examined the influence of maternal postpartum LH on responses to the LH test of offspring. Dam rats were judged as LH or non-helpless (nLH) on postnatal days (PN) 2-3, and maternal behavior was recorded during PN2-14. On PN 45-46, offspring were subjected to the LH test. Plasma corticosterone (CORT) levels, hippocampal levels of glucocorticoid receptor (GR) and brain-derived neurotrophic factor (BDNF) mRNA were measured before and after the LH test in offspring. Active nursing in LH dams was significantly lower than that in nLH dams. Susceptibility to LH in the offspring of LH dams was significantly higher than in those of nLH dams, and was negatively correlated with active nursing by LH dams. The GR mRNA levels before and after the LH test were lower in the offspring of LH dams than in those of nLH dams, and the reduced basal GR mRNA and protein might have resulted in the higher CORT response after the LH test. There was no significant difference in BDNF mRNA in the offspring of LH and nLH dams. These findings suggest that early postpartum LH decreased active nursing and increased depression-like behavior in the adolescent offspring via dysfunction of the hypothalamic-pituitary-adrenal axis.

Dynamics of energy transfer from lycopene to bacteriochlorophyll in genetically-modified LH2 complexes of Rhodobacter sphaeroides.

PubMed

Hörvin Billsten, H; Herek, J L; Garcia-Asua, G; Hashøj, L; Polívka, T; Hunter, C N; Sundström, V

2002-03-26

LH2 complexes from Rb. sphaeroides were modified genetically so that lycopene, with 11 saturated double bonds, replaced the native carotenoids which contain 10 saturated double bonds. Tuning the S1 level of the carotenoid in LH2 in this way affected the dynamics of energy transfer within LH2, which were investigated using both steady-state and time-resolved techniques. The S1 energy of lycopene in n-hexane was determined to be approximately 12 500 +/- 150 cm(-1), by direct measurement of the S1-S2 transient absorption spectrum using a femtosecond IR-probing technique, thus placing an upper limit on the S1 energy of lycopene in the LH2 complex. Fluorescence emission and excitation spectra demonstrated that energy can be transferred from lycopene to the bacteriochlorophyll molecules within this LH2 complex. The energy-transfer dynamics within the mutant complex were compared to wild-type LH2 from Rb. sphaeroides containing the carotenoid spheroidene and from Rs. molischianum, in which lycopene is the native carotenoid. The results show that the overall efficiency for Crt --> B850 energy transfer is approximately 80% in lyco-LH2 and approximately 95% in WT-LH2 of Rb. sphaeroides. The difference in overall Crt --> BChl transfer efficiency of lyco-LH2 and WT-LH2 mainly relates to the low efficiency of the Crt S(1) --> BChl pathway for complexes containing lycopene, which was 20% in lyco-LH2. These results show that in an LH2 complex where the Crt S1 energy is sufficiently high to provide efficient spectral overlap with both B800 and B850 Q(y) states, energy transfer via the Crt S1 state occurs to both pigments. However, the introduction of lycopene into the Rb. sphaeroides LH2 complex lowers the S1 level of the carotenoid sufficiently to prevent efficient transfer of energy to the B800 Q(y) state, leaving only the Crt S1 --> B850 channel, strongly suggesting that Crt S1 --> BChl energy transfer is controlled by the relative Crt S1 and BChl Q(y) energies.

Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2.

PubMed

Ogren, John I; Tong, Ashley L; Gordon, Samuel C; Chenu, Aurélia; Lu, Yue; Blankenship, Robert E; Cao, Jianshu; Schlau-Cohen, Gabriela S

2018-03-28

Photosynthetic purple bacteria convert solar energy to chemical energy with near unity quantum efficiency. The light-harvesting process begins with absorption of solar energy by an antenna protein called Light-Harvesting Complex 2 (LH2). Energy is subsequently transferred within LH2 and then through a network of additional light-harvesting proteins to a central location, termed the reaction center, where charge separation occurs. The energy transfer dynamics of LH2 are highly sensitive to intermolecular distances and relative organizations. As a result, minor structural perturbations can cause significant changes in these dynamics. Previous experiments have primarily been performed in two ways. One uses non-native samples where LH2 is solubilized in detergent, which can alter protein structure. The other uses complex membranes that contain multiple proteins within a large lipid area, which make it difficult to identify and distinguish perturbations caused by protein-protein interactions and lipid-protein interactions. Here, we introduce the use of the biochemical platform of model membrane discs to study the energy transfer dynamics of photosynthetic light-harvesting complexes in a near-native environment. We incorporate a single LH2 from Rhodobacter sphaeroides into membrane discs that provide a spectroscopically amenable sample in an environment more physiological than detergent but less complex than traditional membranes. This provides a simplified system to understand an individual protein and how the lipid-protein interaction affects energy transfer dynamics. We compare the energy transfer rates of detergent-solubilized LH2 with those of LH2 in membrane discs using transient absorption spectroscopy and transient absorption anisotropy. For one key energy transfer step in LH2, we observe a 30% enhancement of the rate for LH2 in membrane discs compared to that in detergent. Based on experimental results and theoretical modeling, we attribute this difference to

Experimental study of temperature sensor for an ocean-going liquid hydrogen (LH2) carrier

NASA Astrophysics Data System (ADS)

Nakano, A.; Shimazaki, T.; Sekiya, M.; Shiozawa, H.; Aoyagi, A.; Ohtsuka, K.; Iwakiri, T.; Mikami, Z.; Sato, M.; Kinoshita, K.; Matsuoka, T.; Takayama, Y.; Yamamoto, K.

2018-04-01

The prototype temperature sensors for an ocean-going liquid hydrogen (LH2) carrier were manufactured by way of trial. All of the sensors adopted Platinum 1000 (PT-1000) resistance thermometer elements. Various configurations of preproduction temperature sensors were tested in AIST's LH2 test facility. In the experiments, a PT-1000 resistance thermometer, calibrated at the National Metrology Institute of Japan at AIST, was used as the standard thermometer. The temperatures measured by the preproduction sensors were compared with the temperatures measured by the standard thermometer, and the measurement accuracy of the temperature sensors in LH2 was investigated and discussed. It was confirmed that the measurement accuracies of the preproduction temperature sensors were within ±50 mK, which is the required measurement accuracy for a technical demonstration ocean-going LH2 carrier.

Production of Antiserum to LH-Releasing Hormone (LH-RH) Associated with Gonadal Atrophy in Rabbits: Development of Radioimmunoassays for LH-RH

DOE Office of Scientific and Technical Information (OSTI.GOV)

ARIMURA, A.; SATO, H.; KUMASAKA, T.

1973-11-01

Repeated injections of synthetic LH -- RH decapeptide, adsorbed on polyvinylpyrrolidone and emulsified with complete Freund's adjuvant, resulted in the production of a specific antiserum to LH-- RH in two of three rabbits. The animals that produced this antiserum showed a reduction of pituitary LH content and marked atrophy of the testes. The antiserum-antibody complex was detected by the complement flxation test. The antiserum was capable of binding /sup 125/I- labeled LH--RH. After iodination of LHRH (using /sup 125/I and either the chloramine T or lactoperoxidase method) separation of the iodination products on CMC yielded three main peaks of radioactivity:more » The first was free iodide, the second was labeled peptide with low immunoreactivity, and the third was immunoreactive peptide. This 3rd peak consisted of two or three subpeaks; the leading subpeak(s) were more readily bound by antiserum than the trailing one(s). Binding of these fractions to antiserum was increased in the presence of small amounts of unlabeled LH--RH (a phenomenon called paradoxical binding or hock effect) but inhibited by larger amounts. Both the augmentation and the inhibition effects were dose-related, allowing the development of two different radioimmunoassay (RIA) systems for LH--RH. An ordinary (coinpetitive) type of RIA was developed in which a small amount (0.31 ng/assay tube) of unlabeled LH-- RH was added to the labeled peptide. This saturated the antiserum's capacity for paradoxical binding, so that further addition of LH-- RH (from 0.04 to 2.5 ng/ tube) inhibited binding of labeled LH--RH. The assay developed using paradoxical binding omitted the premixing of labeled and unlabeled LH--RH; in this assay addition of very small amounts (0.5 to 310 pg) of unlabeled LH--RH to the assay tubes increased the amount of label bound to antiserum and allowed construction of a parabolic curve of positive slope when B/T was plotted against arithmetic dose. The assays seem to be highly

The electronically excited states of LH2 complexes from Rhodopseudomonas acidophila strain 10050 studied by time-resolved spectroscopy and dynamic Monte Carlo simulations. I. Isolated, non-interacting LH2 complexes.

PubMed

Pflock, Tobias J; Oellerich, Silke; Southall, June; Cogdell, Richard J; Ullmann, G Matthias; Köhler, Jürgen

2011-07-21

We have employed time-resolved spectroscopy on the picosecond time scale in combination with dynamic Monte Carlo simulations to investigate the photophysical properties of light-harvesting 2 (LH2) complexes from the purple photosynthetic bacterium Rhodopseudomonas acidophila. The variations of the fluorescence transients were studied as a function of the excitation fluence, the repetition rate of the excitation and the sample preparation conditions. Here we present the results obtained on detergent solubilized LH2 complexes, i.e., avoiding intercomplex interactions, and show that a simple four-state model is sufficient to grasp the experimental observations quantitatively without the need for any free parameters. This approach allows us to obtain a quantitative measure for the singlet-triplet annihilation rate in isolated, noninteracting LH2 complexes.

Fine tuning of the spectral properties of LH2 by single amino acid residues.

PubMed

Silber, Martina V; Gabriel, Günther; Strohmann, Brigitte; Garcia-Martin, Adela; Robert, Bruno; Braun, Paula

2008-05-01

The peripheral light-harvesting complex, LH2, of Rhodobacter sphaeroides consists of an assembly of membrane-spanning alpha and beta polypeptides which assemble the photoactive bacteriochlorophyll and carotenoid molecules. In this study we systematically investigated bacteriochlorophyll-protein interactions and their effect on functional bacteriochlorophyll assembly by site-directed mutations of the LH2 alpha-subunit. The amino acid residues, isoleucine at position -1 and serine at position -4 were replaced by 12 and 13 other residues, respectively. All residues replacing isoleucine at position -1 supported the functional assembly of LH2. The replacement of isoleucine by glycine, glutamine or asparagine, however, produced LH2 complex with significantly altered spectral properties in comparison to LH2 WT. As indicated by resonance Raman spectroscopy extensive rearrangement of the bacteriochlorophyll-B850 macrocycle(s) took place in LH2 in which isoleucine -1 was replaced by glycine. The replacement results in disruption of the H-bond between the C3 acetyl groups and the aromatic residues +13/+14 without affecting the H-bond involving the C13(1) keto group. In contrast, nearly all amino acid replacements of serine at position -4 resulted in shifting of the bacteriochlorophyll-B850 red most absorption maximum. Interestingly, the extent of shifting closely correlated with the volume of the residue at position -4. These results illustrate that fine tuning of the spectral properties of the bacteriochlorophyll-B850 molecules depend on their packing with single amino acid residues at distinct positions.

Single-molecule spectroscopy reveals that individual low-light LH2 complexes from Rhodopseudomonas palustris 2.1.6. have a heterogeneous polypeptide composition.

PubMed

Brotosudarmo, Tatas H P; Kunz, Ralf; Böhm, Paul; Gardiner, Alastair T; Moulisová, Vladimíra; Cogdell, Richard J; Köhler, Jürgen

2009-09-02

Rhodopseudomonas palustris belongs to the group of purple bacteria that have the ability to produce LH2 complexes with unusual absorption spectra when they are grown at low-light intensity. This ability is often related to the presence of multiple genes encoding the antenna apoproteins. Here we report, for the first time to our knowledge, direct evidence that individual low-light LH2 complexes have a heterogeneous alphabeta-apoprotein composition that modulates the site energies of Bchl a molecules, producing absorption bands at 800, 820, and 850 nm. The arrangement of the Bchl a molecules in the "tightly coupled ring" can be modeled by nine alphabeta-Bchls dimers, such that the Bchls bound to six alphabeta-pairs have B820-like site energies and the remaining Bchl a molecules have B850-like site energies. Furthermore, the experimental data can only be satisfactorily modeled when these six alphabeta-pairs with B820 Bchl a molecules are distributed such that the symmetry of the assembly is reduced to C(3). It is also clear from the measured single-molecule spectra that the energies of the electronically excited states in the mixed B820/850 ring are mainly influenced by diagonal disorder.

Down-regulation of pituitary receptors for luteinizing hormone-releasing hormone (LH-RH) in rats by LH-RH antagonist Cetrorelix.

PubMed Central

Halmos, G; Schally, A V; Pinski, J; Vadillo-Buenfil, M; Groot, K

1996-01-01

Antagonists of luteinizing hormone-releasing hormone (LH-RH), unlike the LH-RH agonists, suppress gonadotropins and sex steroid secretion immediately after administration, without initial stimulatory effects. [Ac-D-Nal(2)1,D-Ph(4Cl)2,D-Pal(3)3,D-Cit6,D-Ala10]LH-R H (SB-75; Cetrorelix) is a modern, potent antagonistic analog of LH-RH. In this study, the binding characteristics of receptors for LH-RH in membrane fractions from rat anterior pituitaries were investigated after a single injection of Cetrorelix at a dose of 100 microg per rat. To determine whether the treatment with Cetrorelix can affect the concentration of measurable LH-RH binding sites, we applied an in vitro method to desaturate LH-RH receptors by chaotropic agents such as manganous chloride (MnCl2) and ammonium thiocyanate (NH4SCN). Our results show that the percentages of occupied LH-RH receptors at 1, 3, and 6 h after administration of Cetrorelix were approximately 28%, 14%, and 10%, respectively, of total receptors. At later time intervals, we could not detect occupied LH-RH binding sites. Ligand competition assays, following in vitro desaturation, demonstrated that rat pituitary LH-RH receptors were significantly (P < 0.01) down-regulated for at least 72 h after administration of Cetrorelix. The lowest receptor concentration was found 3-6 h after Cetrorelix treatment and a recovery in receptor number began within approximately 24 h. The down-regulation of LH-RH binding sites induced by Cetrorelix was accompanied by serum LH and testosterone suppression. Higher LH-RH receptor concentrations coincided with elevated serum hormone levels at later time intervals. Our results indicate that administration of LH-RH antagonist Cetrorelix produces a marked down-regulation of pituitary receptors for LH-RH and not merely an occupancy of binding sites. PMID:8637885

Involvement of the C-terminal extension of the alpha polypeptide and of the PucC protein in LH2 complex biosynthesis in Rubrivivax gelatinosus.

PubMed

Steunou, Anne-Soisig; Ouchane, Soufian; Reiss-Husson, Françoise; Astier, Chantal

2004-05-01

The facultative phototrophic nonsulfur bacterium Rubrivivax gelatinosus exhibits several differences from other species of purple bacteria in the organization of its photosynthetic genes. In particular, the puc operon contains only the pucB and pucA genes encoding the beta and alpha polypeptides of the light-harvesting 2 (LH2) complex. Downstream of the pucBA operon is the pucC gene in the opposite transcriptional orientation. The transcription of pucBA and pucC has been studied. No pucC transcript was detected either by Northern blotting or by reverse transcription-PCR analysis. The initiation site of pucBA transcription was determined by primer extension, and Northern blot analysis revealed the presence of two transcripts of 0.8 and 0.65 kb. The half-lives of both transcripts are longer in cells grown semiaerobically than in photosynthetically grown cells, and the small transcript is the less stable. It was reported that the alpha polypeptide, encoded by the pucA gene, presents a C-terminal extension which is not essential for LH2 function in vitro. The biological role of this alanine- and proline-rich C-terminal extension in vivo has been investigated. Two mutants with C-terminal deletions of 13 and 18 residues have been constructed. Both present the two pucBA transcripts, while their phenotypes are, respectively, LH2+ and LH2-, suggesting that a minimal length of the C-terminal extension is required for LH2 biogenesis. Another important factor involved in the LH2 biogenesis is the PucC protein. To gain insight into the function of this protein in R. gelatinosus, we constructed and characterized a PucC mutant. The mutant is devoid of LH2 complex under semiaerobiosis but still produces a small amount of these antennae under photosynthetic growth conditions. This conditional phenotype suggests the involvement of another factor in LH2 biogenesis.

LOX/LH2 vane pump for auxiliary propulsion systems

NASA Technical Reports Server (NTRS)

Hemminger, J. A.; Ulbricht, T. E.

1985-01-01

Positive displacement pumps offer potential efficiency advantages over centrifugal pumps for future low thrust space missions. Low flow rate applications, such as space station auxiliary propulsion or dedicated low thrust orbiter transfer vehicles, are typical of missions where low flow and high head rise challenge centrifugal pumps. The positive displacement vane pump for pumping of LOX and LH2 is investigated. This effort has included: (1) a testing program in which pump performance was investigated for differing pump clearances and for differing pump materials while pumping LN2, LOX, and LH2; and (2) an analysis effort, in which a comprehensive pump performance analysis computer code was developed and exercised. An overview of the theoretical framework of the performance analysis computer code is presented, along with a summary of analysis results. Experimental results are presented for pump operating in liquid nitrogen. Included are data on the effects on pump performance of pump clearance, speed, and pressure rise. Pump suction performance is also presented.

Cost Beneftt Analysts of LH2 PadB

NASA Technical Reports Server (NTRS)

Mott, Brittany

2013-01-01

This analysis is used to evaluate, from a cost and benefit perspective, potential outcomes when replacing the pressurization switches and the pressurization system to meet the needs of the LH2 storage system at Pad B. This also includes alternatives, tangible and intangible benefits, and the results of the analysis.

Regulation of LH/FSH expression by secretoglobin 3A2 in the mouse pituitary gland.

PubMed

Miyano, Yuki; Tahara, Shigeyuki; Sakata, Ichiro; Sakai, Takafumi; Abe, Hiroyuki; Kimura, Shioko; Kurotani, Reiko

2014-04-01

Secretoglobin (SCGB) 3A2 was originally identified as a downstream target for the homeodomain transcription factor NKX2-1 in the lung. NKX2-1 plays a role in the genesis and expression of genes in the thyroid, lung and ventral forebrain; Nkx2-1-null mice have no thyroid and pituitary and severely hypoplastic lungs and hypothalamus. To demonstrate whether SCGB3A2 plays any role in pituitary hormone production, NKX2-1 and SCGB3A2 expression in the mouse pituitary gland was examined by immunohistochemical analysis and RT-PCR. NKX2-1 was localized in the posterior pituitary lobe, whereas SCGB3A2 was observed in both anterior and posterior lobes as shown by immunohistochemistry and RT-PCR. Expression of CCAAT-enhancer binding proteins (C/EBPs), which regulate mouse Scgb3a2 transcription, was also examined by RT-PCR. C/EBPβ, γ, δ and ζ were expressed in the adult mouse pituitary gland. SCGB3A2 was expressed in the anterior and posterior lobes from postnatal days 1 and 5, respectively and the areas where SCGB3A2 expression was found coincided with the area where FSH-secreting cells were found. Double-staining for SCGB3A2 and pituitary hormones revealed that SCGB3A2 was mainly localized in gonadotrophs in 49 % of FSH-secreting cells and 47 % of LH-secreting cells. In addition, SCGB3A2 dramatically inhibited LH and FSH mRNA expression in rat pituitary primary cell cultures. These results suggest that SCGB3A2 regulates FSH/LH production in the anterior pituitary lobe and that transcription factors other than NKX2-1 may regulate SCGB3A2 expression.

Development of LOX/LH2 tank system for H-I launch vehicle

NASA Astrophysics Data System (ADS)

Nozaki, Y.; Takamatsu, H.; Morino, Y.; Imagawa, K.

Design features of the second stage of the prospective Japanese H-1 launch vehicle are described. The stage will use an LO2/LH2 fueled engine. The fuels will be contained in a 2219 Al alloy tank insulated with sprayed polyurethane foam. The total stage length will be 5.5 m, the volume 6.8 m, pressure 3.2 kg/sq cm (LOX) and 2.5 kg/sq cm (LH2). The diameter is 2.5 m and total fuel mass is 8.7 tons. Design verification tests, consisting of burning tests and thermal evaluation, are scheduled for the near future.

Triplet Excitation Transfer between Carotenoids in the LH2 Complex from Photosynthetic Bacterium Rhodopseudomonas palustris.

PubMed

Feng, Juan; Wang, Qian; Wu, Yi-Shi; Ai, Xi-Cheng; Zhang, Xu-Jia; Huang, You-Guo; Zhang, Xing-Kang; Zhang, Jian-Ping

2004-01-01

We have studied, by means of sub-microsecond time-resolved absorption spectroscopy, the triplet-excited state dynamics of carotenoids (Cars) in the intermediate-light adapted LH2 complex (ML-LH2) from Rhodopseudomonas palustris containing Cars with different numbers of conjugated double bonds. Following pulsed photo-excitation at 590 nm at room temperature, rapid spectral equilibration was observed either as a red shift of the isosbestic wavelength on a time scale of 0.6-1.0 mus, or as a fast decay in the shorter-wavelength side of the T(n)<--T(1) absorption of Cars with a time constant of 0.5-0.8 mus. Two major spectral components assignable to Cars with 11 and 12 conjugated double bonds were identified. The equilibration was not observed in the ML-LH2 at 77 K, or in the LH2 complex from Rhodobacter sphaeroides G1C containing a single type of Car. The unique spectral equilibration was ascribed to temperature-dependent triplet excitation transfer among different Car compositions. The results suggest that Cars of 11 and 12 conjugated bonds, both in close proximity of BChls, may coexist in an alpha,beta-subunit of the ML-LH2 complex.

Tissue-specific expression and regulation of the alternatively-spliced forms of lysyl hydroxylase 2 (LH2) in human kidney cells and skin fibroblasts.

PubMed

Walker, Linda C; Overstreet, Mayra A; Yeowell, Heather N

2005-01-01

Lysyl hydroxylases 1, 2, and 3 catalyse the hydroxylation of specific lysines in collagen. A small percentage of these hydroxylysine residues are precursors for the cross-link formation essential for the tensile strength of collagen. Lysyl hydroxylase 2 (LH2) exists as two alternatively-spliced forms; the long transcript (the major ubiquitously-expressed form) includes a 63 bp exon (13A) that is spliced out in the short form (expressed, together with the long form, in human kidney, spleen, liver, and placenta). This study shows that this alternative splicing event can be regulated by both cell density and cycloheximide (CHX). Although only the long form of LH2 is detected in untreated confluent human skin fibroblasts, after 24 h treatment with CHX the short LH2 transcript is also expressed. In kidney cells, in which both LH2 transcripts are equally expressed, the long LH2 transcript is significantly decreased after 24 h CHX treatment, whereas expression of the short transcript is slightly increased. This suggests that, in kidney cells, the splicing mechanism for the inclusion of exon 13A in LH2 requires a newly-synthesized protein factor that is suppressed by CHX, whereas, in skin fibroblasts in which levels of LH2 (long) are unaffected, CHX appears to suppress a factor that inhibits exclusion of exon 13A, thereby promoting expression of LH2 (short). As these alternate transcripts of LH2 may have specificity for hydroxylation of lysines in either telopeptide or helical collagen domains, their relative expression determines the type of cross-links formed, thereby affecting collagen strength. Therefore, any perturbation of the regulation of LH2 splicing could influence the stability of the extracellular matrix and contribute to specific connective tissue disorders.

A replacement LH2 recirculation line before installation in Discovery

NASA Technical Reports Server (NTRS)

1999-01-01

A spare four-inch diameter LH2 recirculation line (shown in photo) will be used to replace a damaged LH2 line in the orbiter Discovery. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. Workers noted a dent in the line during routine aft compartment inspections Tuesday, Dec. 7. The dent measures 12 inches long and about =-inch deep. Managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope.

Adaptation of Rhodopseudomonas acidophila strain 7050 to growth at different light intensities: what are the benefits to changing the type of LH2?

PubMed

Gardiner, A T; Niedzwiedzki, D M; Cogdell, R J

2018-04-01

Typical purple bacterial photosynthetic units consist of light harvesting one/reaction centre 'core' complexes surrounded by light harvesting two complexes. Factors such as the number and size of photosynthetic units per cell, as well as the type of light harvesting two complex that is produced, are controlled by environmental factors. In this paper, the change in the type of LH2 present in the Rhodopsuedomonas acidophila strain 7050 is described when cells are grown at a range of different light intensities. This species contains multiple pucBA genes that encode the apoproteins that form light-harvesting complex two, and a more complex mixture of spectroscopic forms of this complex has been found than was previously thought to be the case. Femto-second time resolved absorption has been used to investigate how the energy transfer properties in the membranes of high-light and low-light adapted cells change as the composition of the LH2 complexes varies.

Dynamics of exciton relaxation in LH2 antenna probed by multipulse nonlinear spectroscopy.

PubMed

Novoderezhkin, Vladimir I; Cohen Stuart, Thomas A; van Grondelle, Rienk

2011-04-28

We explain the relaxation dynamics in the LH2-B850 antenna as revealed by multipulse pump-dump-probe spectroscopy (Th. A. Cohen Stuart, M. Vengris, V. I. Novoderezhkin, R. J. Cogdell, C. N. Hunter, R. van Grondelle, submitted). The theory of pump-dump-probe response is evaluated using the doorway-window approach in combination with the modified Redfield theory. We demonstrate that a simultaneous fit of linear spectra, pump-probe, and pump-dump-probe kinetics can be obtained at a quantitative level using the disordered exciton model, which is essentially the same as used to model the spectral fluctuations in single LH2 complexes (Novoderezhkin, V.; Rutkauskas, D.; van Grondelle, R. Biophys. J. 2006, 90, 2890). The present studies suggest that the observed relaxation rates are strongly dependent on the realization of the disorder. A big spread of the rates (exceeding 3 orders of magnitude) is correlated with the disorder-induced changes in delocalization length and overlap of the exciton wave functions. We conclude that the bulk kinetics reflect a superposition of many pathways corresponding to different physical limits of energy transfer, varying from sub-20 fs relaxation between delocalized and highly spatially overlapping exciton states to >20 ps jumps between states localized at the opposite sides of the ring.

Environment-assisted Quantum Critical Effect for Excitation Energy Transfer in a LH2-type Trimer

NASA Astrophysics Data System (ADS)

Xu, Lan; Xu, Bo

2015-10-01

In this article, we are investigating excitation energy transfer (EET) in a basic unit cell of light-harvesting complex II (LH2), named a LH2-type trimer. Calculation of energy transfer efficiency (ETE) in the framework of non-Markovian environment is also implemented. With these achievements, we theoretically predict the environment-assisted quantum critical effect, where ETE exhibits a sudden change at the critical point of quantum phase transition (QPT) for the LH2-type trimer. It is found that highly efficient EET with nearly unit efficiency may occur in the vicinity of the critical point of QPT.

Carotenoid-bacteriochlorophyll energy transfer in LH2 complexes studied with 10-fs time resolution.

PubMed

Polli, Dario; Cerullo, Giulio; Lanzani, Guglielmo; De Silvestri, Sandro; Hashimoto, Hideki; Cogdell, Richard J

2006-04-01

In this report, we present a study of carotenoid-bacteriochlorophyll energy transfer processes in two peripheral light-harvesting complexes (known as LH2) from purple bacteria. We use transient absorption spectroscopy with approximately 10 fs temporal resolution, which is necessary to observe the very fast energy relaxation processes. By comparing excited-state dynamics of the carotenoids in organic solvents and inside the LH2 complexes, it has been possible to directly evaluate their energy transfer efficiency to the bacteriochlorophylls. In the case of okenone in the LH2 complex from Chromatium purpuratum, we obtained an energy transfer efficiency of etaET2=63+/-2.5% from the optically active excited state (S2) and etaET1=61+/-2% from the optically dark state (S1); for rhodopin glucoside contained in the LH2 complex from Rhodopseudomonas acidophila these values become etaET2=49.5+/-3.5% and etaET1=5.1+/-1%. The measurements also enabled us to observe vibrational energy relaxation in the carotenoids' S1 state and real-time collective vibrational coherence initiated by the ultrashort pump pulses. Our results are important for understanding the dynamics of early events of photosynthesis and relating it to the structural arrangement of the chromophores.

A replacement LH2 recirculation line before installation in Discovery

NASA Technical Reports Server (NTRS)

1999-01-01

Gary Hamilton (left) and James Stickley, both with United Space Alliance, check out a spare four-inch diameter LH2 recirculation line that will be used to replace a damaged LH2 line in the orbiter Discovery. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. Workers noted a dent in the line during routine aft compartment inspections Tuesday, Dec. 7. The dent measures 12 inches long and about =-inch deep. Managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope.

A replacement LH2 recirculation line before installation in Discovery

NASA Technical Reports Server (NTRS)

1999-01-01

James Stickley (left) and Derry Dilby (right), who are with United Space Alliance, check over a spare four-inch diameter LH2 recirculation line that will be used to replace a damaged LH2 line in the orbiter Discovery. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. Workers noted a dent in the line during routine aft compartment inspections Tuesday, Dec. 7. The dent measures 12 inches long and about =-inch deep. Managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope.

Protein-induced geometric constraints and charge transfer in bacteriochlorophyll-histidine complexes in LH2.

PubMed

Wawrzyniak, Piotr K; Alia, A; Schaap, Roland G; Heemskerk, Mattijs M; de Groot, Huub J M; Buda, Francesco

2008-12-14

Bacteriochlorophyll-histidine complexes are ubiquitous in nature and are essential structural motifs supporting the conversion of solar energy into chemically useful compounds in a wide range of photosynthesis processes. A systematic density functional theory study of the NMR chemical shifts for histidine and for bacteriochlorophyll-a-histidine complexes in the light-harvesting complex II (LH2) is performed using the BLYP functional in combination with the 6-311++G(d,p) basis set. The computed chemical shift patterns are consistent with available experimental data for positive and neutral(tau) (N(tau) protonated) crystalline histidines. The results for the bacteriochlorophyll-a-histidine complexes in LH2 provide evidence that the protein environment is stabilizing the histidine close to the Mg ion, thereby inducing a large charge transfer of approximately 0.5 electronic equivalent. Due to this protein-induced geometric constraint, the Mg-coordinated histidine in LH2 appears to be in a frustrated state very different from the formal neutral(pi) (N(pi) protonated) form. This finding could be important for the understanding of basic functional mechanisms involved in tuning the electronic properties and exciton coupling in LH2.

Resonance Raman and surface-enhanced resonance Raman spectra of LH2 antenna complex from Rhodobacter sphaeroides and Ectothiorhodospira sp. excited in the Qx and Qy transitions.

PubMed

Chumanov, G; Picorel, R; Ortiz de Zarate, I; Cotton, T M; Seibert, M

2000-05-01

Well-resolved vibrational spectra of LH2 complex isolated from two photosynthetic bacteria, Rhodobacter sphaeroides and Ectothiorhodospira sp., were obtained using surface-enhanced resonance Raman scattering (SERRS) exciting into the Qx and the Qy transitions of bacteriochlorophyll a. High-quality SERRS spectra in the Qy region were accessible because the strong fluorescence background was quenched near the roughened Ag surface. A comparison of the spectra obtained with 590 nm and 752 nm excitation in the mid- and low-frequency regions revealed spectral differences between the two LH2 complexes as well as between the LH2 complexes and isolated bacteriochlorophyll a. Because peripheral modes of pigments contribute mainly to the low-frequency spectral region, frequencies and intensities of many vibrational bands in this region are affected by interactions with the protein. The results demonstrate that the microenvironment surrounding the pigments within the two LH2 complexes is somewhat different, despite the fact that the complexes exhibit similar electronic absorption spectra. These differences are most probably due to specific pigment-pigment and pigment-protein interactions within the LH2 complexes, and the approach might be useful for addressing subtle static and dynamic structural variances between pigment-protein complexes from different sources or in complexes altered chemically or genetically.

Solvation effect of bacteriochlorophyll excitons in light-harvesting complex LH2.

PubMed

Urboniene, V; Vrublevskaja, O; Trinkunas, G; Gall, A; Robert, B; Valkunas, L

2007-09-15

We have characterized the influence of the protein environment on the spectral properties of the bacteriochlorophyll (Bchl) molecules of the peripheral light-harvesting (or LH2) complex from Rhodobacter sphaeroides. The spectral density functions of the pigments responsible for the 800 and 850 nm electronic transitions were determined from the temperature dependence of the Bchl absorption spectra in different environments (detergent micelles and native membranes). The spectral density function is virtually independent of the hydrophobic support that the protein experiences. The reorganization energy for the B850 Bchls is 220 cm(-1), which is almost twice that of the B800 Bchls, and its Huang-Rhys factor reaches 8.4. Around the transition point temperature, and at higher temperatures, both the static spectral inhomogeneity and the resonance interactions become temperature-dependent. The inhomogeneous distribution function of the transitions exhibits less temperature dependence when LH2 is embedded in membranes, suggesting that the lipid phase protects the protein. However, the temperature dependence of the fluorescence spectra of LH2 cannot be fitted using the same parameters determined from the analysis of the absorption spectra. Correct fitting requires the lowest exciton states to be additionally shifted to the red, suggesting the reorganization of the exciton spectrum.

Comparison of the fluorescence kinetics of detergent-solubilized and membrane-reconstituted LH2 complexes from Rps. acidophila and Rb. sphaeroides.

PubMed

Pflock, Tobias; Dezi, Manuela; Venturoli, Giovanni; Cogdell, Richard J; Köhler, Jürgen; Oellerich, Silke

2008-01-01

Picosecond time-resolved fluorescence spectroscopy has been used in order to compare the fluorescence kinetics of detergent-solubilized and membrane-reconstituted light-harvesting 2 (LH2) complexes from the purple bacteria Rhodopseudomonas (Rps.) acidophila and Rhodobacter (Rb.) sphaeroides. LH2 complexes were reconstituted in phospholipid model membranes at different lipid:protein-ratios and all samples were studied exciting with a wide range of excitation densities. While the detergent-solubilized LH2 complexes from Rps. acidophila showed monoexponential decay kinetics (tau(f )= 980 ps) for excitation densities of up to 3.10(13) photons/(pulse.cm(2)), the membrane-reconstituted LH2 complexes showed multiexponential kinetics even at low excitation densities and high lipid:protein-ratios. The latter finding indicates an efficient clustering of LH2 complexes in the phospholipid membranes. Similar results were obtained for the LH2 complexes from Rb. sphaeroides.

Endophytic bacterial diversity in grapevine (Vitis vinifera L.) leaves described by 16S rRNA gene sequence analysis and length heterogeneity-PCR.

PubMed

Bulgari, Daniela; Casati, Paola; Brusetti, Lorenzo; Quaglino, Fabio; Brasca, Milena; Daffonchio, Daniele; Bianco, Piero Attilio

2009-08-01

Diversity of bacterial endophytes associated with grapevine leaf tissues was analyzed by cultivation and cultivation-independent methods. In order to identify bacterial endophytes directly from metagenome, a protocol for bacteria enrichment and DNA extraction was optimized. Sequence analysis of 16S rRNA gene libraries underscored five diverse Operational Taxonomic Units (OTUs), showing best sequence matches with gamma-Proteobacteria, family Enterobacteriaceae, with a dominance of the genus Pantoea. Bacteria isolation through cultivation revealed the presence of six OTUs, showing best sequence matches with Actinobacteria, genus Curtobacterium, and with Firmicutes genera Bacillus and Enterococcus. Length Heterogeneity-PCR (LH-PCR) electrophoretic peaks from single bacterial clones were used to setup a database representing the bacterial endophytes identified in association with grapevine tissues. Analysis of healthy and phytoplasma-infected grapevine plants showed that LH-PCR could be a useful complementary tool for examining the diversity of bacterial endophytes especially for diversity survey on a large number of samples.

Directed formation of micro- and nanoscale patterns of functional light-harvesting LH2 complexes.

PubMed

Reynolds, Nicholas P; Janusz, Stefan; Escalante-Marun, Maryana; Timney, John; Ducker, Robert E; Olsen, John D; Otto, Cees; Subramaniam, Vinod; Leggett, Graham J; Hunter, C Neil

2007-11-28

The precision placement of the desired protein components on a suitable substrate is an essential prelude to any hybrid "biochip" device, but a second and equally important condition must also be met: the retention of full biological activity. Here we demonstrate the selective binding of an optically active membrane protein, the light-harvesting LH2 complex from Rhodobacter sphaeroides, to patterned self-assembled monolayers at the micron scale and the fabrication of nanometer-scale patterns of these molecules using near-field photolithographic methods. In contrast to plasma proteins, which are reversibly adsorbed on many surfaces, the LH2 complex is readily patterned simply by spatial control of surface polarity. Near-field photolithography has yielded rows of light-harvesting complexes only 98 nm wide. Retention of the native optical properties of patterned LH2 molecules was demonstrated using in situ fluorescence emission spectroscopy.

Fluorescence polarization measures energy funneling in single light-harvesting antennas--LH2 vs conjugated polymers.

PubMed

Camacho, Rafael; Tubasum, Sumera; Southall, June; Cogdell, Richard J; Sforazzini, Giuseppe; Anderson, Harry L; Pullerits, Tõnu; Scheblykin, Ivan G

2015-10-19

Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ε). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ε = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET.

Development tests of LOX/LH 2 tank for H-I launch vehicle

NASA Astrophysics Data System (ADS)

Takamatsu, H.; Imagawa, K.; Ichimaru, Y.

H-I is a future launch vehicle of Japan with a capability of placing more than 550 kg payload into a geostationary orbit. The National Space Development Agency of Japan (NASDA) is now directing its efforts to the final development of H-I launch vehicle. H-I's high launch capability is attained by adopting a newly developed second stage with a LOX/LH 2 propulsion system. The second stage propulsion system consists of a tank and an engine. The tank is 2.5 m in diameter and 5.7 m in length and contains 8.7 tons of propellants. This tank is an integral tank with a common bulkhead which separates the tank into forward LH 2 tank and aft LOX tank. The tank is made of 2219 aluminum alloy and is insulated with sprayed polyurethane foam. The common bulkhead is made of FRP honeycomb core and aluminium alloy surface sheets. The most critical item in the development of the tank is the common bulkhead, therefore the cryogenic structural test was carried out to verify the structural integrity of the bulkhead. The structural integrity of the whole LOX/LH 2 tank was verified by the cryogenic structural test of a sub-scale tank and the room temperature structural test of a prototype tank.

X-33 LH2 Tank Failure Investigation Findings

NASA Technical Reports Server (NTRS)

Niedermeyer, Melinda; Munafo, Paul (Technical Monitor)

2002-01-01

This viewgraph presentation gives an overview of the X-33 LH2 tank failure investigation findings. The conclusions of the investigation include the following: (1) the inner skin microcracked and hydrogen infiltrated; (2) the cracks grew larger under pressure; (3) when pressure was removed, the cracks closed slightly; (4) when the tank was drained and warmed, the cracks closed and blocked the leak path; (5) FOD and debond areas provided an opportunity for a leak path; and (6) there is still hydrogen in the the other three lobes today.

Theory of Excitonic Delocalization for Robust Vibronic Dynamics in LH2.

PubMed

Caycedo-Soler, Felipe; Lim, James; Oviedo-Casado, Santiago; van Hulst, Niek F; Huelga, Susana F; Plenio, Martin B

2018-06-11

Nonlinear spectroscopy has revealed long-lasting oscillations in the optical response of a variety of photosynthetic complexes. Different theoretical models that involve the coherent coupling of electronic (excitonic) or electronic-vibrational (vibronic) degrees of freedom have been put forward to explain these observations. The ensuing debate concerning the relevance of either mechanism may have obscured their complementarity. To illustrate this balance, we quantify how the excitonic delocalization in the LH2 unit of Rhodopseudomonas acidophila purple bacterium leads to correlations of excitonic energy fluctuations, relevant coherent vibronic coupling, and importantly, a decrease in the excitonic dephasing rates. Combining these effects, we identify a feasible origin for the long-lasting oscillations observed in fluorescent traces from time-delayed two-pulse single-molecule experiments performed on this photosynthetic complex and use this approach to discuss the role of this complementarity in other photosynthetic systems.

Carotenoid-to-bacteriochlorophyll energy transfer through vibronic coupling in LH2 from Phaeosprillum molischianum.

PubMed

Thyrhaug, Erling; Lincoln, Craig N; Branchi, Federico; Cerullo, Giulio; Perlík, Václav; Šanda, František; Lokstein, Heiko; Hauer, Jürgen

2018-03-01

The peripheral light-harvesting antenna complex (LH2) of purple photosynthetic bacteria is an ideal testing ground for models of structure-function relationships due to its well-determined molecular structure and ultrafast energy deactivation. It has been the target for numerous studies in both theory and ultrafast spectroscopy; nevertheless, certain aspects of the convoluted relaxation network of LH2 lack a satisfactory explanation by conventional theories. For example, the initial carotenoid-to-bacteriochlorophyll energy transfer step necessary on visible light excitation was long considered to follow the Förster mechanism, even though transfer times as short as 40 femtoseconds (fs) have been observed. Such transfer times are hard to accommodate by Förster theory, as the moderate coupling strengths found in LH2 suggest much slower transfer within this framework. In this study, we investigate LH2 from Phaeospirillum (Ph.) molischianum in two types of transient absorption experiments-with narrowband pump and white-light probe resulting in 100 fs time resolution, and with degenerate broadband 10 fs pump and probe pulses. With regard to the split Q x band in this system, we show that vibronically mediated transfer explains both the ultrafast carotenoid-to-B850 transfer, and the almost complete lack of transfer to B800. These results are beyond Förster theory, which predicts an almost equal partition between the two channels.

Population and coherence dynamics in light harvesting complex II (LH2).

PubMed

Yeh, Shu-Hao; Zhu, Jing; Kais, Sabre

2012-08-28

The electronic excitation population and coherence dynamics in the chromophores of the photosynthetic light harvesting complex 2 (LH2) B850 ring from purple bacteria (Rhodopseudomonas acidophila) have been studied theoretically at both physiological and cryogenic temperatures. Similar to the well-studied Fenna-Matthews-Olson (FMO) protein, oscillations of the excitation population and coherence in the site basis are observed in LH2 by using a scaled hierarchical equation of motion approach. However, this oscillation time (300 fs) is much shorter compared to the FMO protein (650 fs) at cryogenic temperature. Both environment and high temperature are found to enhance the propagation speed of the exciton wave packet yet they shorten the coherence time and suppress the oscillation amplitude of coherence and the population. Our calculations show that a long-lived coherence between chromophore electronic excited states can exist in such a noisy biological environment.

Fluorescence polarization measures energy funneling in single light-harvesting antennas—LH2 vs conjugated polymers

NASA Astrophysics Data System (ADS)

Camacho, Rafael; Tubasum, Sumera; Southall, June; Cogdell, Richard J.; Sforazzini, Giuseppe; Anderson, Harry L.; Pullerits, Tõnu; Scheblykin, Ivan G.

2015-10-01

Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ɛ). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ɛ = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET.

Fluorescence polarization measures energy funneling in single light-harvesting antennas—LH2 vs conjugated polymers

PubMed Central

Camacho, Rafael; Tubasum, Sumera; Southall, June; Cogdell, Richard J.; Sforazzini, Giuseppe; Anderson, Harry L.; Pullerits, Tõnu; Scheblykin, Ivan G.

2015-01-01

Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ε). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ε = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET. PMID:26478272

Singlet-triplet fission of carotenoid excitation in light-harvesting LH2 complexes of purple phototrophic bacteria.

PubMed

Klenina, I B; Makhneva, Z K; Moskalenko, A A; Gudkov, N D; Bolshakov, M A; Pavlova, E A; Proskuryakov, I I

2014-03-01

The current generally accepted structure of light-harvesting LH2 complexes from purple phototrophic bacteria conflicts with the observation of singlet-triplet carotenoid excitation fission in these complexes. In LH2 complexes from the purple bacterium Allochromatium minutissimum, a drop in the efficiency of carotenoid triplet generation is demonstrated, which correlates with the extent of selective photooxidation of bacteriochlorophylls absorbing at ~850 nm. We conclude that singlet-triplet fission of carotenoid excitation proceeds with participation of these excitonically coupled bacteriochlorophylls. In the framework of the proposed mechanism, the contradiction between LH2 structure and photophysical properties of carotenoids is eliminated. The possibility of singlet-triplet excitation fission involving a third mediator molecule was not considered earlier.

LH and hCG Action on the Same Receptor Results in Quantitatively and Qualitatively Different Intracellular Signalling

PubMed Central

Casarini, Livio; Lispi, Monica; Longobardi, Salvatore; Milosa, Fabiola; La Marca, Antonio; Tagliasacchi, Daniela; Pignatti, Elisa; Simoni, Manuela

2012-01-01

Human luteinizing hormone (hLH) and chorionic gonadotropin (hCG) act on the same receptor (LHCGR) but it is not known whether they elicit the same cellular and molecular response. This study compares for the first time the activation of cell-signalling pathways and gene expression in response to hLH and hCG. Using recombinant hLH and recombinant hCG we evaluated the kinetics of cAMP production in COS-7 and hGL5 cells permanently expressing LHCGR (COS-7/LHCGR, hGL5/LHCGR), as well as cAMP, ERK1/2, AKT activation and progesterone production in primary human granulosa cells (hGLC). The expression of selected target genes was measured in the presence or absence of ERK- or AKT-pathways inhibitors. In COS-7/LHCGR cells, hCG is 5-fold more potent than hLH (cAMP ED50: 107.1±14.3 pM and 530.0±51.2 pM, respectively). hLH maximal effect was significantly faster (10 minutes by hLH; 1 hour by hCG). In hGLC continuous exposure to equipotent doses of gonadotropins up to 36 hours revealed that intracellular cAMP production is oscillating and significantly higher by hCG versus hLH. Conversely, phospho-ERK1/2 and -AKT activation was more potent and sustained by hLH versus hCG. ERK1/2 and AKT inhibition removed the inhibitory effect on NRG1 (neuregulin) expression by hLH but not by hCG; ERK1/2 inhibition significantly increased hLH- but not hCG-stimulated CYP19A1 (aromatase) expression. We conclude that: i) hCG is more potent on cAMP production, while hLH is more potent on ERK and AKT activation; ii) hGLC respond to equipotent, constant hLH or hCG stimulation with a fluctuating cAMP production and progressive progesterone secretion; and iii) the expression of hLH and hCG target genes partly involves the activation of different pathways depending on the ligand. Therefore, the LHCGR is able to differentiate the activity of hLH and hCG. PMID:23071612

Single-molecule spectroscopy unmasks the lowest exciton state of the B850 assembly in LH2 from Rps. acidophila.

PubMed

Kunz, Ralf; Timpmann, Kõu; Southall, June; Cogdell, Richard J; Freiberg, Arvi; Köhler, Jürgen

2014-05-06

We have recorded fluorescence-excitation and emission spectra from single LH2 complexes from Rhodopseudomonas (Rps.) acidophila. Both types of spectra show strong temporal spectral fluctuations that can be visualized as spectral diffusion plots. Comparison of the excitation and emission spectra reveals that for most of the complexes the lowest exciton transition is not observable in the excitation spectra due to the cutoff of the detection filter characteristics. However, from the spectral diffusion plots we have the full spectral and temporal information at hand and can select those complexes for which the excitation spectra are complete. Correlating the red most spectral feature of the excitation spectrum with the blue most spectral feature of the emission spectrum allows an unambiguous assignment of the lowest exciton state. Hence, application of fluorescence-excitation and emission spectroscopy on the same individual LH2 complex allows us to decipher spectral subtleties that are usually hidden in traditional ensemble spectroscopy. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Single-Molecule Spectroscopy Unmasks the Lowest Exciton State of the B850 Assembly in LH2 from Rps. acidophila

PubMed Central

Kunz, Ralf; Timpmann, Kõu; Southall, June; Cogdell, Richard J.; Freiberg, Arvi; Köhler, Jürgen

2014-01-01

We have recorded fluorescence-excitation and emission spectra from single LH2 complexes from Rhodopseudomonas (Rps.) acidophila. Both types of spectra show strong temporal spectral fluctuations that can be visualized as spectral diffusion plots. Comparison of the excitation and emission spectra reveals that for most of the complexes the lowest exciton transition is not observable in the excitation spectra due to the cutoff of the detection filter characteristics. However, from the spectral diffusion plots we have the full spectral and temporal information at hand and can select those complexes for which the excitation spectra are complete. Correlating the red most spectral feature of the excitation spectrum with the blue most spectral feature of the emission spectrum allows an unambiguous assignment of the lowest exciton state. Hence, application of fluorescence-excitation and emission spectroscopy on the same individual LH2 complex allows us to decipher spectral subtleties that are usually hidden in traditional ensemble spectroscopy. PMID:24806933

Stability of integral membrane proteins under high hydrostatic pressure: the LH2 and LH3 antenna pigment-protein complexes from photosynthetic bacteria.

PubMed

Kangur, Liina; Timpmann, Kõu; Freiberg, Arvi

2008-07-03

The bacteriochlorophyll a-containing LH2 and LH3 antenna complexes are the integral membrane proteins that catalyze the photosynthetic process in purple photosynthetic bacteria. The LH2 complex from Rhodobacter sphaeroides shows characteristic strong absorbance at 800 and 850 nm due to the pigment molecules confined in two separate areas of the protein. In the LH3 complex from Rhodopesudomonas acidophila the corresponding bands peak at 800 and 820 nm. Using the bacteriochlorophyll a cofactors as intrinsic probes to monitor local changes in the protein structure, we investigate spectral responses of the antenna complexes to very high hydrostatic pressures up to 2.5 GPa when embedded into natural membrane environment or extracted with detergent. We first demonstrate that high pressure does induce significant alterations to the tertiary structure of the proteins not only in proximity of the 800 nm-absorbing bacteriochlorophyll a molecules known previously (Gall, A.; et al. Biochemistry 2003, 42, 13019) but also of the 850 nm- and 820 nm-absorbing molecules, including breakage of the hydrogen bond they are involved in. The membrane-protected complexes appear more resilient to damaging effects of the compression compared with the complexes extracted into mixed detergent-buffer environment. Increased resistance of the isolated complexes is observed at high protein concentration resulting aggregation as well as when cosolvent (glycerol) is added into the solution. These stability variations correlate with ability of penetration of the surrounding polar solvent (water) into the hydrophobic protein interiors, being thus the principal reason of the pressure-induced denaturation of the proteins. Considerable variability of elastic properties of the isolated complexes was also observed, tentatively assigned to heterogeneous protein packing in detergent micelles. While a number of the isolated complexes release most of their bacteriochlorophyll a content under high pressure

Carotenoid radical cation formation in LH2 of purple bacteria: a quantum chemical study.

PubMed

Wormit, Michael; Dreuw, Andreas

2006-11-30

In LH2 complexes of Rhodobacter sphaeroides the formation of a carotenoid radical cation has recently been observed upon photoexcitation of the carotenoid S2 state. To shed more light onto the yet unknown molecular mechanism leading to carotenoid radical formation in LH2, the interactions between carotenoid and bacteriochlorophyll in LH2 are investigated by means of quantum chemical calculations for three different carotenoids--neurosporene, spheroidene, and spheroidenone--using time-dependent density functional theory. Crossings of the calculated potential energy curve of the electron transfer state with the bacteriochlorophyll Qx state and the carotenoid S1 and S2 states occur along an intermolecular distance coordinate for neurosporene and spheroidene, but for spheroidenone no crossing of the electron transfer state with the carotenoid S1 state could be found. By comparison with recent experiments where no formation of a spheroidenone radical cation has been observed, a molecular mechanism for carotenoid radical cation formation is proposed in which it is formed via a vibrationally excited carotenoid S1 or S*state. Arguments are given why the formation of the carotenoid radical cation does not proceed via the Qx, S2, or higher excited electron transfer states.

Space Shuttle - Bringing cryohydrogen technology down to earth. [details of LH2 and LO2 technology and External Tank design

NASA Technical Reports Server (NTRS)

Odom, J. B.

1978-01-01

The External Tank must provide a safe storage container for both LH2 and LO2, a means of maintaining propellant quality in order to meet the engine pump net positive suction pressure requirements, and a structural strong-back for the Space Shuttle system, all at the minimum recurring cost and weight, while maintaining quality and reliability. The present paper summarizes External Tank design features and discusses the advantages of using LH2 and LO2 for the Space Shuttle system.

Preclinical Investigations Reveal the Broad-Spectrum Neutralizing Activity of Peptide Pep19-2.5 on Bacterial Pathogenicity Factors

PubMed Central

Sánchez-Gómez, Susana; Martinez de Tejada, Guillermo; Dömming, Sabine; Brandenburg, Julius; Kaconis, Yani; Hornef, Mathias; Dupont, Aline; Marwitz, Sebastian; Goldmann, Torsten; Ernst, Martin; Gutsmann, Thomas; Schürholz, Tobias

2013-01-01

Bacterial infections are known to cause severe health-threatening conditions, including sepsis. All attempts to get this disease under control failed in the past, and especially in times of increasing antibiotic resistance, this leads to one of the most urgent medical challenges of our times. We designed a peptide to bind with high affinity to endotoxins, one of the most potent pathogenicity factors involved in triggering sepsis. The peptide Pep19-2.5 reveals high endotoxin neutralization efficiency in vitro, and here, we demonstrate its antiseptic/anti-inflammatory effects in vivo in the mouse models of endotoxemia, bacteremia, and cecal ligation and puncture, as well as in an ex vivo model of human tissue. Furthermore, we show that Pep19-2.5 can bind and neutralize not only endotoxins but also other bacterial pathogenicity factors, such as those from the Gram-positive bacterium Staphylococcus aureus. This broad neutralization efficiency and the additive action of the peptide with common antibiotics makes it an exceptionally appropriate drug candidate against bacterial sepsis and also offers multiple other medication opportunities. PMID:23318793

Reusable LH2 tank technology demonstration through ground test

NASA Technical Reports Server (NTRS)

Bianca, C.; Greenberg, H. S.; Johnson, S. E.

1995-01-01

The paper presents the project plan to demonstrate, by March 1997, the reusability of an integrated composite LH2 tank structure, cryogenic insulation, and thermal protection system (TPS). The plan includes establishment of design requirements and a comprehensive trade study to select the most suitable Reusable Hydrogen Composite Tank system (RHCTS) within the most suitable of 4 candidate structural configurations. The 4 vehicles are winged body with the capability to deliver 25,000 lbs of payload to a circular 220 nm, 51.6 degree inclined orbit (also 40,000 lbs to a 28.5 inclined 150 nm orbit). A prototype design of the selected RHCTS is established to identify the construction, fabrication, and stress simulation and test requirements necessary in an 8 foot diameter tank structure/insulation/TPS test article. A comprehensive development test program supports the 8 foot test article development and involves the composite tank itself, cryogenic insulation, and integrated tank/insulation/TPS designs. The 8 foot diameter tank will contain the integrated cryogenic insulation and TPS designs resulting from this development and that of the concurrent lightweight durable TPS program. Tank ground testing will include 330 cycles of LH2 filling, pressurization, body loading, depressurization, draining, and entry heating.

Overview of LH experiments in JET with an ITER-like wall

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirov, K. K.; Baranov, Yu.; Brix, M.

2014-02-12

An overview of the recent results of Lower Hybrid (LH) experiments at JET with the ITER-like wall (ILW) is presented. Topics relevant to LH wave coupling are addressed as well as issues related to ILW and LH system protections. LH wave coupling was studied in conditions determined by ILW recycling and operational constraints. It was concluded that LH wave coupling was not significantly affected and the pre-ILW performance could be recovered after optimising the launcher position and local gas puffing. SOL density measurements were performed using a Li-beam diagnostic. Dependencies on the D2 injection rate from the dedicated gas valve,more » the LH power and the LH launcher position were analysed. SOL density modifications due to LH were modelled by the EDGE2D code assuming SOL heating by collisional dissipation of the LH wave and/or possible ExB drifts in the SOL. The simulations matched reasonably well the measured SOL profiles. Observations of arcs and hotspots with visible and IR cameras viewing the LH launcher are presented.« less

Study of fuel systems for LH2-fueled subsonic transport aircraft, volume 1

NASA Technical Reports Server (NTRS)

Brewer, G. D.; Morris, R. E.; Davis, G. W.; Versaw, E. F.; Cunnington, G. R., Jr.; Riple, J. C.; Baerst, C. F.; Garmong, G.

1978-01-01

Several engine concepts examined to determine a preferred design which most effectively exploits the characteristics of hydrogen fuel in aircraft tanks received major emphasis. Many candidate designs of tank structure and cryogenic insulation systems were evaluated. Designs of all major elements of the aircraft fuel system including pumps, lines, valves, regulators, and heat exchangers received attention. Selected designs of boost pumps to be mounted in the LH2 tanks, and of a high pressure pump to be mounted on the engine were defined. A final design of LH2-fueled transport aircraft was established which incorporates a preferred design of fuel system. That aircraft was then compared with a conventionally fueled counterpart designed to equivalent technology standards.

ASASSN-15lh: A highly super-luminous supernova

NASA Astrophysics Data System (ADS)

Dong, Subo; Shappee, B. J.; Prieto, J. L.; Jha, S. W.; Stanek, K. Z.; Holoien, T. W.-S.; Kochanek, C. S.; Thompson, T. A.; Morrell, N.; Thompson, I. B.; Basu, U.; Beacom, J. F.; Bersier, D.; Brimacombe, J.; Brown, J. S.; Bufano, F.; Chen, Ping; Conseil, E.; Danilet, A. B.; Falco, E.; Grupe, D.; Kiyota, S.; Masi, G.; Nicholls, B.; Olivares E., F.; Pignata, G.; Pojmanski, G.; Simonian, G. V.; Szczygiel, D. M.; Woźniak, P. R.

2016-01-01

We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as the most luminous supernova yet found. At redshift z = 0.2326, ASASSN-15lh reached an absolute magnitude of Mu,AB = -23.5 ± 0.1 and bolometric luminosity Lbol = (2.2 ± 0.2) × 1045 ergs s-1, which is more than twice as luminous as any previously known supernova. It has several major features characteristic of the hydrogen-poor super-luminous supernovae (SLSNe-I), whose energy sources and progenitors are currently poorly understood. In contrast to most previously known SLSNe-I that reside in star-forming dwarf galaxies, ASASSN-15lh appears to be hosted by a luminous galaxy (MK ≈ -25.5) with little star formation. In the 4 months since first detection, ASASSN-15lh radiated (1.1 ± 0.2) × 1052 ergs, challenging the magnetar model for its engine.

Ovarian hyperstimulation, hyperprolactinaemia and LH gonadotroph adenoma.

PubMed

Castelo-Branco, Camil; del Pino, Marta; Valladares, Esther

2009-08-01

This report considers a highly exceptional case of ovarian hyperstimulation syndrome due to a gonadotroph adenoma secreting LH in a 31-year-old patient who presented with amenorrhoea and galactorrhoea syndrome and a complex bilateral ovarian mass. Magnetic resonance imaging revealed a pituitary adenoma, and laboratory tests corroborated the hyperprolactinaemia without other hormonal pituitary abnormalities. Ovarian hyperstimulation syndrome due to a gonadotroph adenoma with normal gonadotrophins is extremely rare. Most of the described cases are caused by FSH adenomas. Due to the originality of the case, it was considered useful for understanding the management of this entity, and it is proposed that LH adenomas should also be considered in the differential diagnosis of patients with spontaneous ovarian hyperstimulation syndrome.

Proinflammatory Cytokine Infusion Attenuates LH's Feedforward on Testosterone Secretion: Modulation by Age.

PubMed

Veldhuis, Johannes; Yang, Rebecca; Roelfsema, Ferdinand; Takahashi, Paul

2016-02-01

In the experimental animal, inflammatory signals quench LH's feedforward drive of testosterone (T) secretion and appear to impair GnRH-LH output. The degree to which such suppressive effects operate in the human is not known. To test the hypothesis that IL-2 impairs LH's feedforward drive on T and T's feedback inhibition of LH secretion in healthy men. Mayo Center for Translational Science Activities. A total of 35 healthy men, 17 young and 18 older. Randomized prospective double-blind saline-controlled study of IL-2 infusion in 2 doses with concurrent 10-minute blood sampling for 24 hours. Deconvolution analysis of LH and T secretion. After saline injection, older compared with young men exhibited reduced LH feedforward drive on T secretion (P < .001), and decreased T feedback inhibition of LH secretion (P < .01). After IL-2 injection, LH's feedforward onto T secretion declined markedly especially in young subjects (P < .001). Concomitantly, IL-2 potentiated T's proportional feedback on LH secretion especially in older volunteers. This investigation confirms combined feedforward and feedback deficits in older relative to young men given saline and demonstrates 1) joint mechanisms by which IL-2 enforces biochemical hypogonadism, viz, combined feedforward block and feedback amplification; and 2) unequal absolute inhibition of T and LH secretion by IL-2 in young and older men. These outcomes establish that the male gonadal axis is susceptible to dual-site suppression by a prototypic inflammatory mediator. Thus, we postulate that selected ILs might also enforce male hypogonadism in chronic systemic inflammation.

Towards revealing the structure of bacterial inclusion bodies.

PubMed

Wang, Lei

2009-01-01

Protein aggregation is a widely observed phenomenon in human diseases, biopharmaceutical production, and biological research. Protein aggregates are generally classified as highly ordered, such as amyloid fibrils, or amorphous, such as bacterial inclusion bodies. Amyloid fibrils are elongated filaments with diameters of 6-12 nm, they are comprised of residue-specific cross-beta structure, and display characteristic properties, such as binding with amyloid-specific dyes. Amyloid fibrils are associated with dozens of human pathological conditions, including Alzheimer disease and prion diseases. Distinguished from amyloid fibrils, bacterial inclusion bodies display apparent amorphous morphology. Inclusion bodies are formed during high-level recombinant protein production, and formation of inclusion bodies is a major concern in biotechnology. Despite of the distinctive morphological difference, bacterial inclusion bodies have been found to have some amyloid-like properties, suggesting that they might contain structures similar to amyloid-like fibrils. Recent structural data further support this hypothesis, and this review summarizes the latest progress towards revealing the structural details of bacterial inclusion bodies.

An Ab Initio Description of the Excitonic Properties of LH2 and Their Temperature Dependence.

PubMed

Cupellini, Lorenzo; Jurinovich, Sandro; Campetella, Marco; Caprasecca, Stefano; Guido, Ciro A; Kelly, Sharon M; Gardiner, Alastair T; Cogdell, Richard; Mennucci, Benedetta

2016-11-10

The spectroscopic properties of light-harvesting (LH) antennae in photosyntehtic organisms represent a fingerprint that is unique for each specific pigment-protein complex. Because of that, spectroscopic observations are generally combined with structural data from X-ray crystallography to obtain an indirect representation of the excitonic properties of the system. Here, an alternative strategy is presented which goes beyond this empirical approach and introduces an ab initio computational description of both structural and electronic properties and their dependence on the temperature. The strategy is applied to the peripheral light-harvesting antenna complex (LH2) present in purple bacteria. By comparing this model with the one based on the crystal structure, a detailed, molecular level explanation of the absorption and circular dichroism (CD) spectra and their temperature dependence is achieved. The agreement obtained with the experiments at both low and room temperature lays the groundwork for an atomistic understanding of the excitation dynamics in the LH2 system.

Proinflammatory Cytokine Infusion Attenuates LH's Feedforward on Testosterone Secretion: Modulation by Age

PubMed Central

Yang, Rebecca; Roelfsema, Ferdinand; Takahashi, Paul

2016-01-01

Context: In the experimental animal, inflammatory signals quench LH's feedforward drive of testosterone (T) secretion and appear to impair GnRH-LH output. The degree to which such suppressive effects operate in the human is not known. Objective: To test the hypothesis that IL-2 impairs LH's feedforward drive on T and T's feedback inhibition of LH secretion in healthy men. Setting: Mayo Center for Translational Science Activities. Patients or Other Participants: A total of 35 healthy men, 17 young and 18 older. Interventions: Randomized prospective double-blind saline-controlled study of IL-2 infusion in 2 doses with concurrent 10-minute blood sampling for 24 hours. Main Outcome Measures: Deconvolution analysis of LH and T secretion. Results: After saline injection, older compared with young men exhibited reduced LH feedforward drive on T secretion (P < .001), and decreased T feedback inhibition of LH secretion (P < .01). After IL-2 injection, LH's feedforward onto T secretion declined markedly especially in young subjects (P < .001). Concomitantly, IL-2 potentiated T's proportional feedback on LH secretion especially in older volunteers. Conclusion: This investigation confirms combined feedforward and feedback deficits in older relative to young men given saline and demonstrates 1) joint mechanisms by which IL-2 enforces biochemical hypogonadism, viz, combined feedforward block and feedback amplification; and 2) unequal absolute inhibition of T and LH secretion by IL-2 in young and older men. These outcomes establish that the male gonadal axis is susceptible to dual-site suppression by a prototypic inflammatory mediator. Thus, we postulate that selected ILs might also enforce male hypogonadism in chronic systemic inflammation. PMID:26600270

LH (Luteinizing Hormone) Test

MedlinePlus

... to predict ovulation by detecting a woman's monthly pre-ovulation LH surge. It indicates ovulation but cannot, however, be used to confirm that ovulation has occurred. Why would a man need a test for FSH and LH; I thought these were ...

Effects of ICRF power on SOL density profiles and LH coupling during simultaneous LH and ICRF operation on Alcator C-Mod

NASA Astrophysics Data System (ADS)

Lau, C.; Lin, Y.; Wallace, G.; Wukitch, S. J.; Hanson, G. R.; Labombard, B.; Ochoukov, R.; Shiraiwa, S.; Terry, J.

2013-09-01

A dedicated experiment during simultaneous lower hybrid (LH) and ion cyclotron range-of-frequencies (ICRF) operations is carried out to evaluate and understand the effects of ICRF power on the scrape-off-layer (SOL) density profiles and on the resultant LH coupling for a wide range of plasma parameters on Alcator C-Mod. Operation of the LH launcher with the adjacent ICRF antenna significantly degrades LH coupling while operation with the ICRF antenna that is not magnetically connected to the LH launcher minimally affects LH coupling. An X-mode reflectometer system at three poloidal locations adjacent to the LH launcher and a visible video camera imaging the LH launcher are used to measure local SOL density profile and emissivity modifications with the application of LH and LH + ICRF power. These measurements confirm that the density in front of the LH launcher depends strongly on the magnetic field line mapping of the active ICRF antenna. Reflectometer measurements also observe both ICRF-driven and LH-driven poloidal density profile asymmetries, especially a strong density depletion at certain poloidal locations in front of the LH launcher during operation with a magnetically connected ICRF antenna. The results indicate that understanding both LH-driven flows and ICRF sheath driven flows may be necessary to understand the observed density profile modifications and LH coupling results during simultaneous LH + ICRF operation.

Towards revealing the structure of bacterial inclusion bodies

PubMed Central

2009-01-01

Protein aggregation is a widely observed phenomenon in human diseases, biopharmaceutical production, and biological research. Protein aggregates are generally classified as highly ordered, such as amyloid fibrils, or amorphous, such as bacterial inclusion bodies. Amyloid fibrils are elongated filaments with diameters of 6–12 nm, they are comprised of residue-specific cross-β structure, and display characteristic properties, such as binding with amyloid-specific dyes. Amyloid fibrils are associated with dozens of human pathological conditions, including Alzheimer disease and prion diseases. Distinguished from amyloid fibrils, bacterial inclusion bodies display apparent amorphous morphology. Inclusion bodies are formed during high-level recombinant protein production, and formation of inclusion bodies is a major concern in biotechnology. Despite of the distinctive morphological difference, bacterial inclusion bodies have been found to have some amyloid-like properties, suggesting that they might contain structures similar to amyloid-like fibrils. Recent structural data further support this hypothesis, and this review summarizes the latest progress towards revealing the structural details of bacterial inclusion bodies. PMID:19806034

Astronomy. ASASSN-15lh: A highly super-luminous supernova.

PubMed

Dong, Subo; Shappee, B J; Prieto, J L; Jha, S W; Stanek, K Z; Holoien, T W-S; Kochanek, C S; Thompson, T A; Morrell, N; Thompson, I B; Basu, U; Beacom, J F; Bersier, D; Brimacombe, J; Brown, J S; Bufano, F; Chen, Ping; Conseil, E; Danilet, A B; Falco, E; Grupe, D; Kiyota, S; Masi, G; Nicholls, B; Olivares E, F; Pignata, G; Pojmanski, G; Simonian, G V; Szczygiel, D M; Woźniak, P R

2016-01-15

We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as the most luminous supernova yet found. At redshift z = 0.2326, ASASSN-15lh reached an absolute magnitude of Mu ,AB = -23.5 ± 0.1 and bolometric luminosity Lbol = (2.2 ± 0.2) × 10(45) ergs s(-1), which is more than twice as luminous as any previously known supernova. It has several major features characteristic of the hydrogen-poor super-luminous supernovae (SLSNe-I), whose energy sources and progenitors are currently poorly understood. In contrast to most previously known SLSNe-I that reside in star-forming dwarf galaxies, ASASSN-15lh appears to be hosted by a luminous galaxy (MK ≈ -25.5) with little star formation. In the 4 months since first detection, ASASSN-15lh radiated (1.1 ± 0.2) × 10(52) ergs, challenging the magnetar model for its engine. Copyright © 2016, American Association for the Advancement of Science.

Shuttle Main Propulsion System LH2 Feed Line and Inducer Simulations

NASA Technical Reports Server (NTRS)

Dorney, Daniel J.; Rothermel, Jeffry

2002-01-01

This viewgraph presentation includes simulations of the unsteady flow field in the LH2 feed line, flow line, flow liner, backing cavity and inducer of Shuttle engine #1. It also evaluates aerodynamic forcing functions which may contribute to the formation of the cracks observed on the flow liner slots. The presentation lists the numerical methods used, and profiles a benchmark test case.

An Evaluation of LH-Stimulated Testosterone Production by ...

EPA Pesticide Factsheets

An Evaluation of LH-Stimulated Testosterone Production by Highly Purified Rat Leydig Cells: A Complementary Screen for Steroidogenesis in the Testis. 1Botteri, N., 2Suarez, J., 2Laws, S., 2Klinefelter, G.1Oak Ridge Institute for Science and Education, Oak Ridge, TN, 2 U.S. Environmental Protection Agency, ORD, NHEERL, TAD, RTP, NCThe H295R steroidogenesis assay uses an adrenocarcinoma cell line which fails to elicit LH mediated responses. This limits the assay’s ability to detect chemicals which disrupt LH-mediated Leydig cell responses in the testis. This study evaluated whether LH-stimulated T production by purified rat Leydig cells would be altered after exposure to chemicals that failed to decrease T production in the ToxCast H295R screen. Ten chemicals negative for T inhibition in the H295R screen, were selected based on alterations in upstream substrates (deoxycorticosterone, hydroxyprogesterone) expected to result in a decrease in T. Based on earlier work, simvastatin served as our positive control. Each chemical was tested over 6 concentrations ranging from 0.1 µM to 100 µM. Leydig cells were cultured overnight under maximal LH stimulation. A minimum of 3 replicate experiments were conducted for each format (24 and 96 well) and chemical tested; cell viability was assessed using a live/dead cytotoxicity kit. T data were excluded if viability was less than 80% of control. Initial evaluation using a 24-well Leydig cell assay confir

Nocturnal Urinary Excretion of FSH and LH in Children and Adolescents With Normal and Early Puberty.

PubMed

Kolby, Nanna; Busch, Alexander S; Aksglaede, Lise; Sørensen, Kaspar; Petersen, Jorgen Holm; Andersson, Anna-Maria; Juul, Anders

2017-10-01

Clinical use of single serum gonadotropin measurements in children is limited by the pulsatile secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). However, first morning voided (FMV) urine may integrate the fluctuating gonadotropin serum levels. We aimed to evaluate urinary and serum gonadotropin levels according to age, sex, and pubertal stage in healthy children and to assess the clinical use of FMV urinary gonadotropins in children with disordered puberty. Cross-sectional part of the COPENHAGEN Puberty Study and longitudinal study of patients. Population-based and outpatient clinic. Eight hundred forty-three healthy children from the COPENHAGEN Puberty Study and 25 girls evaluated for central precocious puberty (CPP). Clinical pubertal staging, including serum and urinary gonadotropin levels. Urinary gonadotropins increased with advancing age and pubertal development and were detectable in FMV urine before physical signs of puberty. FMV urinary LH correlated strongly with basal (r = 0.871, P < 0.001) and gonadotropin-releasing hormone (GnRH)-stimulated serum LH (r = 0.82, P < 0.001). Urinary LH was superior to urinary FSH in differentiating the pubertal stage. Receiver operating curve analysis revealed that a cut-off standard deviation (SD) score of 2 for urinary LH (IU/L) gave a sensitivity of 75% and a specificity of 92% in predicting a positive GnRH stimulation test (LHmax > 5 IU/L). Urinary concentrations of LH decreased after 3 months of GnRH treatment to levels below +2 SDs. Urinary gonadotropin levels increased before the onset of puberty and were elevated in girls with CPP. We suggest urinary LH as an alternative noninvasive method to improve diagnosing and therapeutic management of children with disordered puberty. Copyright © 2017 Endocrine Society

B800-B850 coherence correlates with energy transfer rates in the LH2 complex of photosynthetic purple bacteria.

PubMed

Smyth, Cathal; Oblinsky, Daniel G; Scholes, Gregory D

2015-12-14

Until recently, no analytical measure of many-body delocalization in open systems had been developed, yet such a measure enables characterization of how molecular excitons delocalize in photosynthetic light-harvesting complexes, and in turn helps us understand quantum coherent aspects of electronic energy transfer. In this paper we apply these measures to a model peripheral light-harvesting complex, LH2 from Rhodopseudomonas acidophila. We find how many chromophores collectively contribute to the "delocalization length" of an excitation within LH2 and how the coherent delocalization is distributed spatially. We also investigate to what extent this delocalization length is effective, by examining the impact of bipartite and multipartite entanglement in inter-ring energy transfer in LH2.

The Evolution of Utilizing Manual Throttles to Avoid Low LH2 NPSP at the SSME Inlet

NASA Technical Reports Server (NTRS)

Henfling, Rick

2011-01-01

Even before the first flight of the Space Shuttle, it was understood low liquid hydrogen (LH2) Net Positive Suction Pressure (NPSP) at the inlet to the Space Shuttle Main Engine (SSME) can have adverse effects on engine operation. A number of failures within both the External Tank (ET) and the Orbiter Main Propulsion System could result in a low LH2 NPSP condition. Operational workarounds were developed to take advantage of the onboard crew s ability to manually throttle down the SSMEs, which alleviated the low LH2 NPSP condition. A throttling down of the SSME resulted in an increase in NPSP, mainly due to the reduction in frictional flow losses while at a lower throttle setting. As engineers refined their understanding of the NPSP requirements for the SSME (through a robust testing program), the operational techniques evolved to take advantage of these additional capabilities. Currently the procedure, which for early Space Shuttle missions required a Return-to-Launch-Site abort, now would result in a nominal Main Engine Cut Off (MECO) and no loss of mission objectives.

Controlled Ovarian Hyperstimulation with Intrauterine Insemination Is More Successful After r-hCG Administration Than Spontaneous LH Surge.

PubMed

Taerk, Evan; Hughes, Edward; Greenberg, Cassandra; Neal, Michael; Amin, Shilpa; Faghih, Mehrnoosh; Karnis, Megan

2017-01-01

The purpose of this study was to evaluate whether clinical pregnancy rate is affected by timing intrauterine insemination (IUI) according to serum LH surge, r-hCG trigger, or a combination of LH surge and r-hCG trigger in controlled ovarian hyperstimulation (COH) cycles for patients with a variety of infertility etiologies. The last 365 consecutive COH-IUI cycles performed at ONE Fertility Burlington in 2014 were reviewed and categorized according to method of IUI timing. Associations between categorical variables were analyzed using a combination of Chi-square and Fisher's Exact tests, and between continuous variables using independent sample t-tests and logistic regression to a level of significance of p<0.05. The overall clinical pregnancy rate in this sample was 18.1% (66/365). Administration of r-hCG prior to IUI resulted in a higher clinical pregnancy rate compared with spontaneous serum LH surge: 18.2% vs . 5.8%, p=0.012. Patients in whom r-hCG was administered concomitantly with a serum LH surge had a higher clinical pregnancy than the r-hCG trigger group (30.8% vs . 18.2%, p=0.004) and LH surge group (30.8% vs . 5.8%, p<0.001). A sub-group analysis revealed that patients receiving r-FSH, rather than clomiphene or letrozole, had a significantly higher clinical pregnancy rate after r-hCG trigger as compared to the LH surge group (21.7% vs . 2.1%, p=0.01). In subfertile couples undergoing COH-IUI, r-hCG administration was associated with an increased clinical pregnancy rate compared with spontaneous serum LH surge. When r-hCG was administered concomitantly with a serum LH surge, this benefit was amplified. The effect appears to be of particular importance in r-FSH-medicated cycles.

The origin of the split B800 absorption peak in the LH2 complexes from Allochromatium vinosum.

PubMed

Löhner, Alexander; Carey, Anne-Marie; Hacking, Kirsty; Picken, Nichola; Kelly, Sharon; Cogdell, Richard; Köhler, Jürgen

2015-01-01

The absorption spectrum of the high-light peripheral light-harvesting (LH) complex from the photosynthetic purple bacterium Allochromatium vinosum features two strong absorptions around 800 and 850 nm. For the LH2 complexes from the species Rhodopseudomonas acidophila and Rhodospirillum molischianum, where high-resolution X-ray structures are available, similar bands have been observed and were assigned to two pigment pools of BChl a molecules that are arranged in two concentric rings (B800 and B850) with nine (acidophila) or eight (molischianum) repeat units, respectively. However, for the high-light peripheral LH complex from Alc. vinosum, the intruiging feature is that the B800 band is split into two components. We have studied this pigment-protein complex by ensemble CD spectroscopy and polarisation-resolved single-molecule spectroscopy. Assuming that the high-light peripheral LH complex in Alc. vinosum is constructed on the same modular principle as described for LH2 from Rps. acidophila and Rsp. molischianum, we used those repeat units as a starting point for simulating the spectra. We find the best agreement between simulation and experiment for a ring-like oligomer of 12 repeat units, where the mutual arrangement of the B800 and B850 rings resembles those from Rsp. molischianum. The splitting of the B800 band can be reproduced if both an excitonic coupling between dimers of B800 molecules and their interaction with the B850 manifold are taken into account. Such dimers predict an interesting apoprotein organisation as discussed below.

LH-RH binding to purified pituitary plasma membranes: absence of adenylate cyclase activation.

PubMed

Clayton, R N; Shakespear, R A; Marshall, J C

1978-06-01

Purified bovine pituitary plasma membranes possess two specific LH-RH binding sites. The high affinity site (2.5 X 10(9) l/mol) has low capacity (9 X 10(-15) mol/mg membrane protein) while the low affinity site 6.1 X 10(5) l/mol) has a much higher capacity (1.1 X 10(-10) mol/mg). Specific LH-RH binding to plasma membranes is increased 8.5-fold during purification from homogenate whilst adenylate cyclase activity is enriched 7--8-fold. Distribution of specific LH-RH binding to sucrose density gradient interface fractions parallels that of adenylate cyclase activity. Mg2+ and Ca2+ inhibit specific [125I]LH-RH binding at micromolar concentrations. Synthetic LH-RH, up to 250 microgram/ml, failed to stimulate adenylase cyclase activity of the purified bovine membranes. Using a crude 10,800 g rat pituitary membrane preparation, LH-RH similarly failed to activate adenylate cyclase even in the presence of guanyl nucleotides. These data confirm the presence of LH-RH receptor sites on pituitary plasma membranes and suggest that LH-RH-induced gonadotrophin release may be mediated by mechanisms other than activation of adenylate cyclase.

Evidence of excited state localization and static disorder in LH2 investigated by 2D-polarization single-molecule imaging at room temperature.

PubMed

Tubasum, Sumera; Camacho, Rafael; Meyer, Matthias; Yadav, Dheerendra; Cogdell, Richard J; Pullerits, Tõnu; Scheblykin, Ivan G

2013-12-07

Two-dimensional polarization fluorescence imaging of single light harvesting complexes 2 (LH2) of Rps. acidophila was carried out to investigate the polarization properties of excitation and fluorescence emission simultaneously, at room temperature. In two separate experiments we excited LH2 with a spectrally narrow laser line matched to the absorption bands of the two chromophore rings, B800 and B850, thereby indirectly and directly triggering fluorescence of the B850 exciton state. A correlation analysis of the polarization modulation depths in excitation and emission for a large number of single complexes was performed. Our results show, in comparison to B800, that the B850 ring is a more isotropic absorber due to the excitonic nature of its excited states. At the same time, we observed a strong tendency for LH2 to emit with dipolar character, from which preferential localization of the emissive exciton, stable for minutes, is inferred. We argue that the observed effects can consistently be explained by static energetic disorder and/or deformation of the complex, with possible involvement of exciton self-trapping.

In vivo intra-luteal implants of prostaglandin (PG) E(1) or E(2) (PGE(1), PGE(2)) prevent luteolysis in cows. I. Luteal weight, circulating progesterone, mRNA for luteal luteinizing hormone (LH) receptor, and occupied and unoccupied luteal receptors for LH.

PubMed

Weems, Yoshie S; Arreguin-Arevalo, J Alejandro; Nett, Torrance M; Vann, Rhonda C; Ford, Stephen P; Bridges, Phillip J; Welsh, Thomas H; Lewis, Andrew W; Neuendorff, Don A; Randel, Ronald D; Weems, Charles W

2011-08-01

Previously, it was reported that chronic intra-uterine infusion of PGE(1) or PGE(2) every four hours inhibited luteolysis in ewes. However, estradiol-17β or PGE(2) given intra-uterine every 8h did not inhibit luteolysis in heifers, but infusion of estradiol+PGE(2) inhibited luteolysis in heifers. The objective of this experiment was to determine whether and how intra-luteal implants containing PGE(1) or PGE(2) prevent luteolysis in Angus or Brahman cows. On day-13 post-estrus, Angus cows received no intra-luteal implant and corpora lutea were retrieved or Angus and Brahman cows received intra-luteal silastic implants containing Vehicle, PGE(1), or PGE(2) and corpora lutea were retrieved on day-19. Coccygeal blood was collected daily for analysis for progesterone. Breed did not influence the effect of PGE(1) or PGE(2) on luteal mRNA for LH receptors or unoccupied or occupied luteal LH receptors did not differ (P>0.05) so the data were pooled. Luteal weights of Vehicle-treated Angus or Brahman cows from days-13-19 were lower (P<0.05) than those treated with intra-luteal implants containing PGE(1) or PGE(2). Day-13 Angus luteal weights were heavier (P<0.05) than Vehicle-treated Angus cows on day-19 and luteal weights of day-13 corpora lutea were similar (P>0.05) to Angus cows on day-19 treated with intra-luteal implants containing PGE(1) or PGE(2). Profiles of circulating progesterone in Angus or Brahman cows treated with intra-luteal implants containing PGE(1) or PGE(2) differed (P<0.05) from controls, but profiles of progesterone did not differ (P>0.05) between breeds or between cows treated with intra-luteal implants containing PGE(1) or PGE(2). Intra-luteal implants containing PGE(1) or PGE(2) prevented (P<0.05) loss of luteal mRNA for LH receptors and unoccupied or occupied receptors for LH compared to controls. It is concluded that PGE(1) or PGE(2) alone delays luteolysis regardless of breed. We also conclude that either PGE(1) or PGE(2) prevented luteolysis in

Differences in Signal Activation by LH and hCG are Mediated by the LH/CG Receptor’s Extracellular Hinge Region

PubMed Central

Grzesik, Paul; Kreuchwig, Annika; Rutz, Claudia; Furkert, Jens; Wiesner, Burkhard; Schuelein, Ralf; Kleinau, Gunnar; Gromoll, Joerg; Krause, Gerd

2015-01-01

The human lutropin (hLH)/choriogonadotropin (hCG) receptor (LHCGR) can be activated by binding two slightly different gonadotropic glycoprotein hormones, choriogonadotropin (CG) – secreted by the placenta, and lutropin (LH) – produced by the pituitary. They induce different signaling profiles at the LHCGR. This cannot be explained by binding to the receptor’s leucine-rich-repeat domain (LRRD), as this binding is similar for the two hormones. We therefore speculate that there are previously unknown differences in the hormone/receptor interaction at the extracellular hinge region, which might help to understand functional differences between the two hormones. We have therefore performed a detailed study of the binding and action of LH and CG at the LHCGR hinge region. We focused on a primate-specific additional exon in the hinge region, which is located between LRRD and the serpentine domain. The segment of the hinge region encoded by exon10 was previously reported to be only relevant to hLH signaling, as the exon10-deletion receptor exhibits decreased hLH signaling, but unchanged hCG signaling. We designed an advanced homology model of the hormone/LHCGR complex, followed by experimental characterization of relevant fragments in the hinge region. In addition, we examined predictions of a helical exon10-encoded conformation by block-wise polyalanine (helix supporting) mutations. These helix preserving modifications showed no effect on hormone-induced signaling. However, introduction of a structure-disturbing double-proline mutant LHCGR-Q303P/E305P within the exon10-helix has, in contrast to exon10-deletion, no impact on hLH, but only on hCG signaling. This opposite effect on signaling by hLH and hCG can be explained by distinct sites of hormone interaction in the hinge region. In conclusion, our analysis provides details of the differences between hLH- and hCG-induced signaling that are mainly determined in the L2-beta loop of the hormones and in the

Responses to constant infusion of LH-RH in girls with primary hypogonadism.

PubMed

Reiter, E O; Duckett, G E; Root, A W

1980-09-01

To further assess quantitative pituitary gonadotropin release in patients with primary hypogonadism, a 3-hour constant infusion of the synthetic gonadotropin-releasing hormone, LH-RH, was administered to 12 functionally agonadal girls (11 with Turner syndrome and 1 who had been overiectomized), aged 9.5 to 19.42 years. Gonadotropin and sex steroid responses were determined before and during the infusion and contrasted to those in normal pubertal females. in girls with skeletal age under 11 years, mean control LH increased (P < .001) from 2.2 +/- 0.3 (mean +/- SEM) mIU/ml to 21.3 +/- 7.3 during LH-RH infusion, while luteinizing hormone (LH) rose (P < .001) from 89.2 +/- 24.6 to 276.5 +/- 42.6 girls with skeletal age over 11 years. This age-related augmentation is an exaggeration of data in normal girls and occcurs despite minimal gonadal secretion of sex steroids. A similar age-related discrepancy was not seen in follicle-stimulating hormone (FSH) secretion evoked by LH-RH; all girls had FSH increments into the castrate range with a rise from mean control levels of 78.6 +/- 6.7 to 133.9 +/- 8.3. These data demonstrate an age-related increase in LH-RH-evoked LH secretion, but not of FSH, in children and adolescents with primary hypogonadism.

KEA-144: Final Results of the Ground Operations Demonstration Unit for Liquid Hydrogen (GODU-LH2) Project

NASA Technical Reports Server (NTRS)

Notardonato, William; Fesmire, James; Swanger, Adam; Jumper, Kevin; Johnson, Wesley; Tomsik, Thomas

2017-01-01

GODU-LH2 system has successfully met all test objectives at the 33%, 67%, and 100% tank fill level. Complete control over the state of the fluid has been demonstrated using Integrated Refrigeration and Storage (IRAS). Almost any desired point along the H2saturation curve can essentially be "dialed in" and maintained indefinitely. System can also be used to produce densified hydrogen in large quantities to the triple point. Exploring multiple technology infusion paths. Studying implementation of IRAS technology into new LH2sphere for EM-2 at LC39B. Technical interchange also occurring with STMD, LSP, ULA, DoE, KIST, Kawasaki, Shell Oil, SpaceX, US Coast Guard, and Virgin Galactic.

Development and validation of cryogenic foam insulation for LH2 subsonic transports

NASA Technical Reports Server (NTRS)

Anthony, F. M.; Colt, J. Z.; Helenbrook, R. G.

1981-01-01

Fourteen foam insulation specimens were tested. Some were plain foam while others contained flame retardants, chopped fiberglass reinforcement and/or vapor barriers. The thermal performance of the insulation was determined by measuring the rate at which LH2 boiled from an aluminum tank insulated with the test material. The test specimens were approximately 50 mm (2 in.) thick. They were structurally scaled so that the test cycle would duplicate the maximum thermal stresses predicted for the thicker insulation of an aircraft liquid hydrogen fuel tank during a typical subsonic flight. The simulated flight cycle of approximately 10 minutes duration heated the other insulation surface to 316 K (110 F) and cooled it to 226 K (20 F) while the inner insulation surface remained at liquid hydrogen temperature of 20 K (-423 F). Two urethane foam insulations exceeded the initial life goal of 2400 simulated flight cycles and sustained 4400 cycles with only minor damage. The addition of fiberglass reinforcement of flame retardant materials to an insulation degraded thermal performance and/or the life of the foam material. Installation of vapor barriers enhanced the structural integrity of the material but did not improve thermal performance. All of the foams tested were available materials; none were developed specifically for LH2 service.

Exploring the pathophysiology of hypogonadism in men with type 2 diabetes: kisspeptin-10 stimulates serum testosterone and LH secretion in men with type 2 diabetes and mild biochemical hypogonadism.

PubMed

George, Jyothis T; Veldhuis, Johannes D; Tena-Sempere, Manuel; Millar, Robert P; Anderson, Richard A

2013-07-01

Low serum testosterone is commonly observed in men with type 2 diabetes (T2DM), but the neuroendocrine pathophysiology remains to be elucidated. The hypothalamic neuropeptide kisspeptin integrates metabolic signals with the reproductive axis in animal models. We hypothesized that administration of exogenous kisspeptin-10 will restore luteinizing hormone (LH) and testosterone secretion in hypotestosteronaemic men with T2DM. Five hypotestosteronaemic men with T2DM (age 33·6 ± 3 years, BMI 40·6 ± 6·3, total testosterone 8·5 ± 1·0 nmol/l, LH 4·7 ± 0·7 IU/l, HbA1c 7·4±2%, duration of diabetes <5 years) and seven age-matched healthy men. EXPERIMENT 1: Mean LH increased in response to intravenous administration of kisspeptin-10 (0·3 mcg/kg bolus) both in healthy men (5·5 ± 0·8 to 13·9 ± 1·7 IU/l P < 0·001) and in men with T2DM (4·7 ± 0·7 to 10·7 ± 1·2 IU/l P = 0·02) with comparable ΔLH (P = 0·18). EXPERIMENT 2: Baseline 10-min serum sampling for LH and hourly testosterone measurements were performed in four T2DM men over 12 h. An intravenous infusion of kisspeptin-10 (4 mcg/kg/h) was administered for 11 h, 5 days later. There were increases in LH (3·9 ± 0·1 IU/l to 20·7 ± 1·1 IU/l P = 0·03) and testosterone (8·5 ± 1·0 to 11·4 ± 0·9 nmol/l, P = 0·002). LH pulse frequency increased from 0·6 ± 0·1 to 0·9 ± 0 pulses/h (P = 0·05) and pulsatile component of LH secretion from 32·1 ± 8·0 IU/l to 140·2 ± 23·0 IU/l (P = 0·007). Kisspeptin-10 administration increased LH pulse frequency and LH secretion in hypotestosteronaemic men with T2DM in this proof-of-concept study, with associated increases in serum testosterone. These data suggest a potential novel therapeutic role for kisspeptin agonists in enhancing endogenous testosterone secretion in men with T2DM and central hypogonadism. © 2012 John Wiley & Sons Ltd.

Sulfation of LH Does Not Affect Intracellular Trafficking

PubMed Central

Pearl, Christopher A.; Boime, Irving

2009-01-01

LH and FSH are produced by the same gonadotrope cells of the anterior pituitary but differ in their mode of secretion. LH secretion is primarily episodic, or regulated, while FSH secretion is primarily basal, or constitutive. The asparagine (N)-linked oligosaccharides of LH and FSH terminate with sulfate and sialic acid, respectively. TSH also contains sulfated N-linked oligosaccharides and is secreted through the regulated pathway. It has been hypothesized that sulfate plays a role in segregating LH to the regulated pathway. Using a mouse pituitary model, we tested this hypothesis by examining the secretory fate of LH from pituitaries treated with sodium chlorate, a known inhibitor of sulfation. Here we show that mouse LH is sulfated and secreted through the regulated pathway, while FSH is secreted constitutively. LH secretion from chlorate treated pituitaries, which showed complete inhibition of sulfation, was similar to untreated pituitaries. These data suggest that the metabolic role for sulfated N-linked oligosaccharides is not for intracellular trafficking but for the extracellular bioactivity of LH. PMID:19647136

Understanding L-H transition in tokamak fusion plasmas

NASA Astrophysics Data System (ADS)

Xu, Guosheng; Wu, Xingquan

2017-03-01

This paper reviews the current state of understanding of the L-H transition phenomenon in tokamak plasmas with a focus on two central issues: (a) the mechanism for turbulence quick suppression at the L-H transition; (b) the mechanism for subsequent generation of sheared flow. We briefly review recent advances in the understanding of the fast suppression of edge turbulence across the L-H transition. We uncover a comprehensive physical picture of the L-H transition by piecing together a number of recent experimental observations and insights obtained from 1D and 2D simulation models. Different roles played by diamagnetic mean flow, neoclassical-driven mean flow, turbulence-driven mean flow, and turbulence-driven zonal flows are discussed and clarified. It is found that the L-H transition occurs spontaneously mediated by a shift in the radial wavenumber spectrum of edge turbulence, which provides a critical evidence for the theory of turbulence quench by the flow shear. Remaining questions and some key directions for future investigations are proposed. This work was supported by National Magnetic Confinement Fusion Science Program of China under Contracts No. 2015GB101000, No. 2013GB106000, and No. 2013GB107000 and National Natural Science Foundation of China under Contracts No. 11575235 and No. 11422546.

Navier-Stokes computations with finite-rate chemistry for LO2/LH2 rocket engine plume flow studies

NASA Technical Reports Server (NTRS)

Dougherty, N. Sam; Liu, Baw-Lin

1991-01-01

Computational fluid dynamics methods have been developed and applied to Space Shuttle Main Engine LO2/LH2 plume flow simulation/analysis of airloading and convective base heating effects on the vehicle at high flight velocities and altitudes. New methods are described which were applied to the simulation of a Return-to-Launch-Site abort where the vehicle would fly briefly at negative angles of attack into its own plume. A simplified two-perfect-gases-mixing approach is used where one gas is the plume and the other is air at 180-deg and 135-deg flight angle of attack. Related research has resulted in real gas multiple-plume interaction methods with finite-rate chemistry described herein which are applied to the same high-altitude-flight conditions of 0 deg angle of attack. Continuing research plans are to study Orbiter wake/plume flows at several Mach numbers and altitudes during ascent and then to merge this model with the Shuttle 'nose-to-tail' aerodynamic and SRB plume models for an overall 'nose-to-plume' capability. These new methods are also applicable to future launch vehicles using clustered-engine LO2/LH2 propulsion.

Role of B800 in carotenoid-bacteriochlorophyll energy and electron transfer in LH2 complexes from the purple bacterium Rhodobacter sphaeroides.

PubMed

Polívka, Tomas; Niedzwiedzki, Dariusz; Fuciman, Marcel; Sundström, Villy; Frank, Harry A

2007-06-28

The role of the B800 in energy and electron transfer in LH2 complexes has been studied using femtosecond time-resolved transient absorption spectroscopy. The B800 site was perturbed by application of lithium dodecyl sulfate (LDS), and comparison of treated and untreated LH2 complexes from Rhodobacter sphaeroides incorporating carotenoids neurosporene, spheroidene, and spheroidenone was used to explore the role of B800 in carotenoid to bacteriochlorophyll-a (BChla) energy transfer and carotenoid radical formation. Efficiencies of the S1-mediated energy transfer in the LDS-treated complexes were 86, 61, and 57% in the LH2 complexes containing neurosporene, spheroidene, and spheroidenone, respectively. Analysis of the carotenoid S1 lifetimes in solution, LDS-treated, and untreated LH2 complexes allowed determination of B800/B850 branching ratio in the S1-mediated energy transfer. It is shown that B800 is a major acceptor, as approximately 60% of the energy from the carotenoid S1 state is accepted by B800. This value is nearly independent of conjugation length of the carotenoid. In addition to its role in energy transfer, the B800 BChla is the only electron acceptor in the event of charge separation between carotenoid and BChla in LH2 complexes, which is demonstrated by prevention of carotenoid radical formation in the LDS-treated LH2 complexes. In the untreated complexes containing neurosporene and spheroidene, the carotenoid radical is formed with a time constant of 300-400 fs. Application of different excitation wavelengths and intensity dependence of the carotenoid radical formation showed that the carotenoid radical can be formed only after excitation of the S2 state of carotenoid, although the S2 state itself is not a precursor of the charge-separated state. Instead, either a hot S1 state or a charge-transfer state lying between S2 and S1 states of the carotenoid are discussed as potential precursors of the charge-separated state.

Elimination of polarity in the carotenoid terminus promotes the exposure of B850-binding sites (Tyr 44, 45) and ANS-mediated energy transfer in LH2 complexes of Rhodobacter sphaeroides.

PubMed

Liu, Yuan; Wu, Yongqiang; Xu, Chunhe

2004-12-10

Carotenoids in the peripheral light-harvesting complexes (LH2) of the green mutant (GM309) of Rhodobacter sphaeroides were identified as containing neurosporenes, which lack the polar CH(3)O group, compared to spheroidenes in native-LH2 of R. sphaeroides 601. After LH2 complexes were treated with 1-anilino-8-naphthalene sulfonate (ANS), new energy transfer pathways from ANS or tryptophan to carotenoids were discovered in both native- and GM309-LH2. The carotenoid fluorescence intensity of GM309-LH2 was greater than that of native-LH2 when bound with ANS, suggesting that the elimination of polarity in the neurosporene increases the energy transfer from ANS to carotenoid. The fact that two alpha-tyrosines (alpha-Tyr 44, 45, B850-binding sites) in each alpha-apoprotein of GM309-LH2 were more easily modified than those of native-LH2 by N-acetylimidazole (NAI) indicates that the elimination of polarity in the neurosporene terminus increases the exposure of these sites to solution.

Evaluating the Nature of So-Called S*-State Feature in Transient Absorption of Carotenoids in Light-Harvesting Complex 2 (LH2) from Purple Photosynthetic Bacteria.

PubMed

Niedzwiedzki, Dariusz M; Hunter, C Neil; Blankenship, Robert E

2016-11-03

Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S* state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation-bacteriochlorophyll anion pair. These findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes.

Evaluating the Nature of So-Called S*-State Feature in Transient Absorption of Carotenoids in Light-Harvesting Complex 2 (LH2) from Purple Photosynthetic Bacteria

PubMed Central

2016-01-01

Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S* state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation–bacteriochlorophyll anion pair. These findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes. PMID:27726397

Evaluating the nature of so-called S*-State feature in transient absorption of carotenoids in light-harvesting complex 2 (LH2) from purple photosynthetic bacteria

DOE PAGES

Niedzwiedzki, Dariusz M.; Hunter, C. Neil; Blankenship, Robert E.

2016-10-11

Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S*more » state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation- bacteriochlorophyll anion pair. Lastly, these findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes.« less

Evaluating the nature of so-called S*-State feature in transient absorption of carotenoids in light-harvesting complex 2 (LH2) from purple photosynthetic bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niedzwiedzki, Dariusz M.; Hunter, C. Neil; Blankenship, Robert E.

Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S*more » state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation- bacteriochlorophyll anion pair. Lastly, these findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes.« less

The “Ram Effect”: A “Non-Classical” Mechanism for Inducing LH Surges in Sheep

PubMed Central

Fabre-Nys, Claude; Chanvallon, Audrey; Dupont, Joëlle; Lardic, Lionel; Lomet, Didier; Martinet, Stéphanie; Scaramuzzi, Rex J.

2016-01-01

During spring sheep do not normally ovulate but exposure to a ram can induce ovulation. In some ewes an LH surge is induced immediately after exposure to a ram thus raising questions about the control of this precocious LH surge. Our first aim was to determine the plasma concentrations of oestradiol (E2) E2 in anoestrous ewes before and after the “ram effect” in ewes that had a “precocious” LH surge (starting within 6 hours), a “normal” surge (between 6 and 28h) and “late» surge (not detected by 56h). In another experiment we tested if a small increase in circulating E2 could induce an LH surge in anoestrus ewes. The concentration of E2 significantly was not different at the time of ram introduction among ewes with the three types of LH surge. “Precocious” LH surges were not preceded by a large increase in E2 unlike “normal” surges and small elevations of circulating E2 alone were unable to induce LH surges. These results show that the “precocious” LH surge was not the result of E2 positive feedback. Our second aim was to test if noradrenaline (NA) is involved in the LH response to the “ram effect”. Using double labelling for Fos and tyrosine hydroxylase (TH) we showed that exposure of anoestrous ewes to a ram induced a higher density of cells positive for both in the A1 nucleus and the Locus Coeruleus complex compared to unstimulated controls. Finally, the administration by retrodialysis into the preoptic area, of NA increased the proportion of ewes with an LH response to ram odor whereas treatment with the α1 antagonist Prazosin decreased the LH pulse frequency and amplitude induced by a sexually active ram. Collectively these results suggest that in anoestrous ewes NA is involved in ram-induced LH secretion as observed in other induced ovulators. PMID:27384667

High efficiency light harvesting by carotenoids in the LH2 complex from photosynthetic bacteria: unique adaptation to growth under low-light conditions.

PubMed

Magdaong, Nikki M; LaFountain, Amy M; Greco, Jordan A; Gardiner, Alastair T; Carey, Anne-Marie; Cogdell, Richard J; Gibson, George N; Birge, Robert R; Frank, Harry A

2014-09-25

Rhodopin, rhodopinal, and their glucoside derivatives are carotenoids that accumulate in different amounts in the photosynthetic bacterium, Rhodoblastus (Rbl.) acidophilus strain 7050, depending on the intensity of the light under which the organism is grown. The different growth conditions also have a profound effect on the spectra of the bacteriochlorophyll (BChl) pigments that assemble in the major LH2 light-harvesting pigment-protein complex. Under high-light conditions the well-characterized B800-850 LH2 complex is formed and accumulates rhodopin and rhodopin glucoside as the primary carotenoids. Under low-light conditions, a variant LH2, denoted B800-820, is formed, and rhodopinal and rhodopinal glucoside are the most abundant carotenoids. The present investigation compares and contrasts the spectral properties and dynamics of the excited states of rhodopin and rhodopinal in solution. In addition, the systematic differences in pigment composition and structure of the chromophores in the LH2 complexes provide an opportunity to explore the effect of these factors on the rate and efficiency of carotenoid-to-BChl energy transfer. It is found that the enzymatic conversion of rhodopin to rhodopinal by Rbl. acidophilus 7050 grown under low-light conditions results in nearly 100% carotenoid-to-BChl energy transfer efficiency in the LH2 complex. This comparative analysis provides insight into how photosynthetic systems are able to adapt and survive under challenging environmental conditions.

High Efficiency Light Harvesting by Carotenoids in the LH2 Complex from Photosynthetic Bacteria: Unique Adaptation to Growth under Low-Light Conditions

PubMed Central

2015-01-01

Rhodopin, rhodopinal, and their glucoside derivatives are carotenoids that accumulate in different amounts in the photosynthetic bacterium, Rhodoblastus (Rbl.) acidophilus strain 7050, depending on the intensity of the light under which the organism is grown. The different growth conditions also have a profound effect on the spectra of the bacteriochlorophyll (BChl) pigments that assemble in the major LH2 light-harvesting pigment–protein complex. Under high-light conditions the well-characterized B800-850 LH2 complex is formed and accumulates rhodopin and rhodopin glucoside as the primary carotenoids. Under low-light conditions, a variant LH2, denoted B800-820, is formed, and rhodopinal and rhodopinal glucoside are the most abundant carotenoids. The present investigation compares and contrasts the spectral properties and dynamics of the excited states of rhodopin and rhodopinal in solution. In addition, the systematic differences in pigment composition and structure of the chromophores in the LH2 complexes provide an opportunity to explore the effect of these factors on the rate and efficiency of carotenoid-to-BChl energy transfer. It is found that the enzymatic conversion of rhodopin to rhodopinal by Rbl. acidophilus 7050 grown under low-light conditions results in nearly 100% carotenoid-to-BChl energy transfer efficiency in the LH2 complex. This comparative analysis provides insight into how photosynthetic systems are able to adapt and survive under challenging environmental conditions. PMID:25171303

Immunoreactive LH in long-term frozen human urine samples.

PubMed

Singh, Gurmeet Kaur Surindar; Jimenez, Mark; Newman, Ron; Handelsman, David J

2014-04-01

Urine provides a convenient non-invasive alternative to blood sampling for measurement of certain hormones. Urinary luteinizing hormone (LH) measurements have been used for endocrinology research and anti-doping testing. However, the commercially available LH immunoassays are developed and validated for human blood samples but not urine so that LH assays intended for use with urine samples need thorough validation. Therefore, the present study evaluated the measurement of urinary LH immunoreactivity using previously validated immunofluorometric (IF) and immunochemiluminometric (ICL) LH assays after prolonged frozen storage. LH was measured in serial urine samples following administration of a single injection of one of two doses of recombinant human chorionic hormone (rhCG) with assays run at the end of study (2008) and again after four years of frozen (-20 °C) storage where samples were stored without adding preservatives. The ICL assay showed quantitatively reproducible LH measurements after prolonged -20 °C storage. However, the IF immunoassay gave consistently lower LH levels relative to ICL (2008) with a further proportionate reduction after four years of sample storage (2012). Yet, both the assays displayed similar patterns of the time-course of urine LH measurement both before and after four years of frozen storage. In conclusion, we found that both immunoassays are suitable for urinary LH measurements with ICL assay being more robust for quantitative urinary LH measurement such as for anti-doping purposes, whereas the IF could be applicable for research studies where urine LH levels are compared within-study but not in absolute terms. Copyright © 2013 John Wiley & Sons, Ltd.

Next-Generation Sequencing Reveals Significant Bacterial Diversity of Botrytized Wine

PubMed Central

Bokulich, Nicholas A.; Joseph, C. M. Lucy; Allen, Greg; Benson, Andrew K.; Mills, David A.

2012-01-01

While wine fermentation has long been known to involve complex microbial communities, the composition and role of bacteria other than a select set of lactic acid bacteria (LAB) has often been assumed either negligible or detrimental. This study served as a pilot study for using barcoded amplicon next-generation sequencing to profile bacterial community structure in wines and grape musts, comparing the taxonomic depth achieved by sequencing two different domains of prokaryotic 16S rDNA (V4 and V5). This study was designed to serve two goals: 1) to empirically determine the most taxonomically informative 16S rDNA target region for barcoded amplicon sequencing of wine, comparing V4 and V5 domains of bacterial 16S rDNA to terminal restriction fragment length polymorphism (TRFLP) of LAB communities; and 2) to explore the bacterial communities of wine fermentation to better understand the biodiversity of wine at a depth previously unattainable using other techniques. Analysis of amplicons from the V4 and V5 provided similar views of the bacterial communities of botrytized wine fermentations, revealing a broad diversity of low-abundance taxa not traditionally associated with wine, as well as atypical LAB communities initially detected by TRFLP. The V4 domain was determined as the more suitable read for wine ecology studies, as it provided greater taxonomic depth for profiling LAB communities. In addition, targeted enrichment was used to isolate two species of Alphaproteobacteria from a finished fermentation. Significant differences in diversity between inoculated and uninoculated samples suggest that Saccharomyces inoculation exerts selective pressure on bacterial diversity in these fermentations, most notably suppressing abundance of acetic acid bacteria. These results determine the bacterial diversity of botrytized wines to be far higher than previously realized, providing further insight into the fermentation dynamics of these wines, and demonstrate the utility of next

Operational Issues in the Development of a Cost-Effective Reusable LOX/LH2 Engine

NASA Technical Reports Server (NTRS)

Ballard, Richard O.

2005-01-01

Contents include the following: SLI initiated under NASA Research Announcement (NRA) 8-30. Strategic Objectives. Make spaceflight safer (1 in 10000 mission LOV). Make spaceflight cheaper ($1000/lb payload). Two prototype LOX/LH2 engine systems funded under Cycle-1 of NRA8-30. COBRA (Pratt & Whitney / Aerojet). RS-83 (Rocketdyne).

Carotenoid stoichiometry in the LH2 crystal: no spectral evidence for the presence of the second molecule in the alpha/beta-apoprotein dimer.

PubMed

Gall, Andrew; Gardiner, Alastair T; Cogdell, Richard J; Robert, Bruno

2006-07-10

In this work we have investigated the carotenoid-protein interactions in LH2 complexes of Rhodopseudomonas acidophila both in "free in solution" mixed-micelles and in three-dimensional crystals by Raman spectroscopy in resonance with the carotenoid (Car) molecules. We show that the Car molecules when bound to their binding pockets show no significant differences when the complexes are "free in solution" or packed in crystalline arrays. Furthermore, there is no significant wavelength dependence in the Raman spectrum of the Car molecules of LH2. This indicates that there is only one Car configuration in LH2 and thus only one molecule per alpha/beta-heterodimer.

Development tests of LOX/LH2 tank for H-I launch vehicle

NASA Astrophysics Data System (ADS)

Takamatsu, H.; Imagawa, K.; Ichimaru, Y.

1984-10-01

The design and preliminary test performance of an integrated LOX/LH2 tank for the second-stage propulsion system of the H-I launch be vehicle being developed by NASDA are presented and illustrated with drawings, diagrams, photographs, graphs, and tables. The tank has length 5.7 m, diameter 2.5 m, and capacity 8.7 tons and is constructed of 2219 Al alloy. The common bulkhead of Al-alloy-covered GFRP honeycomb, identified as the most critical component, has successfully completed extensive mechanical and thermal testing of both subscale and prototype models.

Research Resource: Preovulatory LH Surge Effects on Follicular Theca and Granulosa Transcriptomes

PubMed Central

Gunewardena, Sumedha; Hong, Xiaoman; Spitschak, Marion; Baufeld, Anja

2013-01-01

The molecular mechanisms that regulate the pivotal transformation processes observed in the follicular wall following the preovulatory LH surge, are still not established, particularly for cells of the thecal layer. To elucidate thecal cell (TC) and granulosa cell (GC) type-specific biologic functions and signaling pathways, large dominant bovine follicles were collected before and 21 hours after an exogenous GnRH-induced LH surge. Antral GCs (aGCs; aspirated by follicular puncture) and membrane-associated GCs (mGCs; scraped from the follicular wall) were compared with TC expression profiles determined by mRNA microarrays. Of the approximately 11 000 total genes expressed in the periovulatory follicle, only 2% of thecal vs 25% of the granulosa genes changed in response to the LH surge. The majority of the 203 LH-regulated thecal genes were also LH regulated in GCs, leaving a total of 57 genes as LH-regulated TC-specific genes. Of the 57 thecal-specific LH-regulated genes, 74% were down-regulated including CYP17A1 and NR5A1, whereas most other genes are being identified for the first time within theca. Many of the newly identified up-regulated thecal genes (eg, PTX3, RND3, PPP4R4) were also up-regulated in granulosa. Minimal expression differences were observed between aGCs and mGCs; however, transcripts encoding extracellular proteins (NID2) and matrix modulators (ADAMTS1, SASH1) dominated these differences. We also identified large numbers of unknown LH-regulated GC genes and discuss their putative roles in ovarian function. This Research Resource provides an easy-to-access global evaluation of LH regulation in TCs and GCs that implicates numerous molecular pathways heretofore unknown within the follicle. PMID:23716604

Research resource: preovulatory LH surge effects on follicular theca and granulosa transcriptomes.

PubMed

Christenson, Lane K; Gunewardena, Sumedha; Hong, Xiaoman; Spitschak, Marion; Baufeld, Anja; Vanselow, Jens

2013-07-01

The molecular mechanisms that regulate the pivotal transformation processes observed in the follicular wall following the preovulatory LH surge, are still not established, particularly for cells of the thecal layer. To elucidate thecal cell (TC) and granulosa cell (GC) type-specific biologic functions and signaling pathways, large dominant bovine follicles were collected before and 21 hours after an exogenous GnRH-induced LH surge. Antral GCs (aGCs; aspirated by follicular puncture) and membrane-associated GCs (mGCs; scraped from the follicular wall) were compared with TC expression profiles determined by mRNA microarrays. Of the approximately 11 000 total genes expressed in the periovulatory follicle, only 2% of thecal vs 25% of the granulosa genes changed in response to the LH surge. The majority of the 203 LH-regulated thecal genes were also LH regulated in GCs, leaving a total of 57 genes as LH-regulated TC-specific genes. Of the 57 thecal-specific LH-regulated genes, 74% were down-regulated including CYP17A1 and NR5A1, whereas most other genes are being identified for the first time within theca. Many of the newly identified up-regulated thecal genes (eg, PTX3, RND3, PPP4R4) were also up-regulated in granulosa. Minimal expression differences were observed between aGCs and mGCs; however, transcripts encoding extracellular proteins (NID2) and matrix modulators (ADAMTS1, SASH1) dominated these differences. We also identified large numbers of unknown LH-regulated GC genes and discuss their putative roles in ovarian function. This Research Resource provides an easy-to-access global evaluation of LH regulation in TCs and GCs that implicates numerous molecular pathways heretofore unknown within the follicle.

Orthotopic transplantation of LH receptor knockout and wild-type ovaries.

PubMed

Chudgar, Daksha; Lei, Zhenmin; Rao, Ch V

2005-10-07

Luteinizing hormone (LH) receptor knockout animals have an ovarian failure due to an arrest in folliculogenesis at the antral stage. As a result, the animals have an infertility phenotype. The present study was undertaken to determine whether this phenotype could be reversed by orthotopic transplantation of wild-type ovaries. The results revealed that transplanting wild-type ovaries into null animals did not result in resumption of estrus cycles. Although the number of different types of follicles increased, none progressed to ovulation. The serum hormone profiles improved, reflecting the ovarian changes. The wild-type animals with null ovaries also failed to cycle and their ovaries and serum hormone levels were more like null animals with their own ovaries. Although the lack of rescue of null ovaries placed into wild-type animals was predicted, the failure of wild-type ovaries placed in null animals was not, which could be due to chronic exposure of transplanted tissue to high circulating LH levels and also possibly due to altered internal milieu in null animals. These findings may have implications for potential future considerations of grafting normal donor ovaries into women who have an ovarian failure resulting from inactivating LH receptor mutations.

Serum LH and FSH Responses to Synthetic LH-RH in Normal Infants, Children and Patients With Turner's Syndrome

ERIC Educational Resources Information Center

Suwa, Seizo; And Others

1974-01-01

Effects of luteinizing hormone-releasing hormone (LH-RH) on LH and follicle-stimulating hormone (FSH) release were studied in 26 normal children and six patients (from 1-to 14-years-old) with Turner's syndrome. (Author)

A simple performance calculation method for LH2/LOX engines with different power cycles

NASA Technical Reports Server (NTRS)

Schmucker, R. H.

1973-01-01

A simple method for the calculation of the specific impulse of an engine with a gas generator cycle is presented. The solution is obtained by a power balance between turbine and pump. Approximate equations for the performance of the combustion products of LH2/LOX are derived. Performance results are compared with solutions of different engine types.

The crystal structures of EAP domains from Staphylococcus aureus reveal an unexpected homology to bacterial superantigens.

PubMed

Geisbrecht, Brian V; Hamaoka, Brent Y; Perman, Benjamin; Zemla, Adam; Leahy, Daniel J

2005-04-29

The Eap (extracellular adherence protein) of Staphylococcus aureus functions as a secreted virulence factor by mediating interactions between the bacterial cell surface and several extracellular host proteins. Eap proteins from different Staphylococcal strains consist of four to six tandem repeats of a structurally uncharacterized domain (EAP domain). We have determined the three-dimensional structures of three different EAP domains to 1.8, 2.2, and 1.35 A resolution, respectively. These structures reveal a core fold that is comprised of an alpha-helix lying diagonally across a five-stranded, mixed beta-sheet. Comparison of EAP domains with known structures reveals an unexpected homology with the C-terminal domain of bacterial superantigens. Examination of the structure of the superantigen SEC2 bound to the beta-chain of a T-cell receptor suggests a possible ligand-binding site within the EAP domain (Fields, B. A., Malchiodi, E. L., Li, H., Ysern, X., Stauffacher, C. V., Schlievert, P. M., Karjalainen, K., and Mariuzza, R. (1996) Nature 384, 188-192). These results provide the first structural characterization of EAP domains, relate EAP domains to a large class of bacterial toxins, and will guide the design of future experiments to analyze EAP domain structure/function relationships.

Sequencing and generation of an infectious clone of the pathogenic goose parvovirus strain LH.

PubMed

Wang, Jianye; Duan, Jinkun; Zhu, Liqian; Jiang, Zhiwei; Zhu, Guoqiang

2015-03-01

In this study, the complete genome of the virulent strain LH of goose parvovirus (GPV) was sequenced and cloned into the pBluescript II (SK) plasmid vector. Sequence alignments of the inverted terminal repeats (ITR) of GPV strains revealed a common 14-nt-pair deletion in the stem of the palindromic structure in the LH strain and three other strains isolated after 1982 when compared to three GPV strains isolated earlier than that time. Transfection of 11-day-old embryonated goose eggs with the plasmid pLH, which contains the entire genome of strain LH, resulted in successful rescue of the infectious virus. Death of embryos after transfection via the chorioallantoic membrane infiltration route occurred earlier than when transfection was done via the allantoic cavity inoculation route. The rescued virus exhibited virulence similar to that of its parental virus, as evaluated by the mortality rate in goslings. Generation of the pathogenic infectious clone provides us with a powerful tool to elucidate the molecular pathogenesis of GPV in the future.

In silico predictions of LH2 ring sizes from the crystal structure of a single subunit using molecular dynamics simulations.

PubMed

Janosi, Lorant; Keer, Harindar; Cogdell, Richard J; Ritz, Thorsten; Kosztin, Ioan

2011-07-01

Most of the currently known light-harvesting complexes 2 (LH2) rings are formed by 8 or 9 subunits. As of now, questions like "what factors govern the LH2 ring size?" and "are there other ring sizes possible?" remain largely unanswered. Here, we investigate by means of molecular dynamics (MD) simulations and stochastic modeling the possibility of predicting the size of an LH2 ring from the sole knowledge of the high resolution crystal structure of a single subunit. Starting with single subunits of two LH2 rings with known size, that is, an 8-ring from Rs. moliscianum (MOLI) and a 9-ring from Rps. acidophila (ACI), and one with unknown size (referred to as X), we build atomic models of subunit dimers corresponding to assumed 8-, 9-, and 10-ring geometries. After inserting each of the dimers into a lipid-water environment, we determine the preferred angle between the corresponding subunits by three methods: (1) energy minimization, (2) free MD simulations, and (3) potential of mean force calculations. We find that the results from all three methods are consistent with each other, and when taken together, it allows one to predict with reasonable level of confidence the sizes of the corresponding ring structures. One finds that X and ACI very likely form a 9-ring, while MOLI is more likely to form an 8-ring than a 9-ring. Finally, we discuss both the merits and limitations of all three prediction methods. Copyright © 2011 Wiley-Liss, Inc.

DATA COLLECTION CONSTRAINTS FOR THE USE OF LENGTH HETEROGENEITY POLYMERASE CHAIN REACTION (LH-PCR) AS AN INDICATOR OF STREAM SANITARY AND ECOLOGICAL CONDITION

EPA Science Inventory

This study is part of a larger project for the development of bacterial indicators of stream sanitary and ecological condition. Here we report preliminary research on the use of Length Heterogeneity Polymerase Chain Reaction (LH-PCR), which discriminates among 16S rRNA genes bas...

Crystal structure of the Haemophilus influenzae Hap adhesin reveals an intercellular oligomerization mechanism for bacterial aggregation

PubMed Central

Meng, Guoyu; Spahich, Nicole; Kenjale, Roma; Waksman, Gabriel; St Geme, Joseph W

2011-01-01

Bacterial biofilms are complex microbial communities that are common in nature and are being recognized increasingly as an important determinant of bacterial virulence. However, the structural determinants of bacterial aggregation and eventual biofilm formation have been poorly defined. In Gram-negative bacteria, a major subgroup of extracellular proteins called self-associating autotransporters (SAATs) can mediate cell–cell adhesion and facilitate biofilm formation. In this study, we used the Haemophilus influenzae Hap autotransporter as a prototype SAAT to understand how bacteria associate with each other. The crystal structure of the H. influenzae HapS passenger domain (harbouring the SAAT domain) was determined to 2.2 Å by X-ray crystallography, revealing an unprecedented intercellular oligomerization mechanism for cell–cell interaction. The C-terminal SAAT domain folds into a triangular-prism-like structure that can mediate Hap–Hap dimerization and higher degrees of multimerization through its F1–F2 edge and F2 face. The intercellular multimerization can give rise to massive buried surfaces that are required for overcoming the repulsive force between cells, leading to bacterial cell–cell interaction and formation of complex microcolonies. PMID:21841773

A Host-Produced Autoinducer-2 Mimic Activates Bacterial Quorum Sensing.

PubMed

Ismail, Anisa S; Valastyan, Julie S; Bassler, Bonnie L

2016-04-13

Host-microbial symbioses are vital to health; nonetheless, little is known about the role crosskingdom signaling plays in these relationships. In a process called quorum sensing, bacteria communicate with one another using extracellular signal molecules called autoinducers. One autoinducer, AI-2, is proposed to promote interspecies bacterial communication, including in the mammalian gut. We show that mammalian epithelia produce an AI-2 mimic activity in response to bacteria or tight-junction disruption. This AI-2 mimic is detected by the bacterial AI-2 receptor, LuxP/LsrB, and can activate quorum-sensing-controlled gene expression, including in the enteric pathogen Salmonella typhimurium. AI-2 mimic activity is induced when epithelia are directly or indirectly exposed to bacteria, suggesting that a secreted bacterial component(s) stimulates its production. Mutagenesis revealed genes required for bacteria to both detect and stimulate production of the AI-2 mimic. These findings uncover a potential role for the mammalian AI-2 mimic in fostering crosskingdom signaling and host-bacterial symbioses. Copyright © 2016 Elsevier Inc. All rights reserved.

Dynamics of the h-LH and h-FSH response after the stimulation test with Gn-RH-LH/FSH in man.

PubMed

Klepsch, I; Grigorescu, A; Eşanu, C

1976-01-01

A study was carried out on a number of 17 subjects concerning the dynamics of LH and FSH response after stimulation with Gn-RH-LH/FSH. The results show a stimulation 10 minutes after quick i.v. injection of synthetic RH, with a peak at 20-30 minutes and a persistence of the response of up to 180 min. The variation of the response is proportional with the dose, the response to stimulation being higher for LH than for FSH. The response in the normal adult male is of 82-858% for LH and of 157-250% for FSH. In aged subjects there is an increased response capacity showing that the hypophysis still reacts at an advanced age, with variations depending on the individual characteristics. In Sheehan's syndrome the basal values of FSH and LH are low, with a slight response after stimulation with RH, suggesting the possibility of a partial regeneration of the hypophysis if any intact areas were left after the initial necrotic process.

The LH2 complexes are assembled in the cells of purple sulfur bacterium Ectothiorhodospira haloalkaliphila with inhibition of carotenoid biosynthesis.

PubMed

Ashikhmin, Aleksandr; Makhneva, Zoya; Moskalenko, Andrey

2014-03-01

The effect of the inhibitor of carotenoid (Car) biosynthesis, diphenylamine (DPA), on the cells of the purple sulfur bacterium Ectothiorhodospira (Ect.) haloalkaliphila has been studied. There occurs an inhibition of the biosynthesis of colored Cars (≥99 %) at 71 μM DPA. Considering "empty" Car pockets (Moskalenko and Makhneva 2012) the content of Cars in the DPA-treated samples is first calculated more correctly. The total content of the colored Cars in the sample at 71 μM DPA does not exceed 1 % of the wild type. In the DPA-treated cells (membranes) a complete set of pigment-protein complexes is retained. The LH2 complex at 71 μM DPA is isolated, which is identical to the LH2 complex of the wild type in near IR absorption spectra. This suggests that the principles for assembling this LH2 complex in vivo in the absence of colored Cars remain the same. These results are in full agreement with the data obtained earlier for Allochromatium (Alc.) minutissimum (Moskalenko and Makhneva 2012). They are as follows: (1) DPA almost entirely inhibits the biosynthesis of the colored Cars in Ect. haloalkaliphila cells. (2) In the DPA-treated samples non-colored Cars are detected at 53.25 μM DPA (as traces) and at 71 μM DPA. (3) DPA may affect both phytoene synthase (at ≤71 μM DPA) and phytoene desaturase (at ≥53.25 μM DPA). (4) The assembly of LH2 complex does occur without any colored Cars.

Physics of GAM-initiated L-H transition in a tokamak

NASA Astrophysics Data System (ADS)

Askinazi, L. G.; Belokurov, A. A.; Bulanin, V. V.; Gurchenko, A. D.; Gusakov, E. Z.; Kiviniemi, T. P.; Lebedev, S. V.; Kornev, V. A.; Korpilo, T.; Krikunov, S. V.; Leerink, S.; Machielsen, M.; Niskala, P.; Petrov, A. V.; Tukachinsky, A. S.; Yashin, A. Yu; Zhubr, N. A.

2017-01-01

Based on experimental observations using the TUMAN-3M and FT-2 tokamaks, and the results of gyrokinetic modeling of the interplay between turbulence and the geodesic acoustic mode (GAM) in these installations, a simple model is proposed for the analysis of the conditions required for L-H transition triggering by a burst of radial electric field oscillations in a tokamak. In the framework of this model, one-dimensional density evolution is considered to be governed by an anomalous diffusion coefficient dependent on radial electric field shear. The radial electric field is taken as the sum of the oscillating term and the quasi-stationary one determined by density and ion temperature gradients through a neoclassical formula. If the oscillating field parameters (amplitude, frequency, etc) are properly adjusted, a transport barrier forms at the plasma periphery and sustains after the oscillations are switched off, manifesting a transition into the high confinement mode with a strong inhomogeneous radial electric field and suppressed transport at the plasma edge. The electric field oscillation parameters required for L-H transition triggering are compared with the GAM parameters observed at the TUMAN-3M (in the discharges with ohmic L-H transition) and FT-2 tokamaks (where no clear L-H transition was observed). It is concluded based on this comparison that the GAM may act as a trigger for the L-H transition, provided that certain conditions for GAM oscillation and tokamak discharge are met.

Development of advanced materials composites for use as insulations for LH2 tanks

NASA Technical Reports Server (NTRS)

Lemons, C. R.; Salmassy, O. K.

1973-01-01

A study of thread-reinforced polyurethane foam and glass fabric liner, serving as internally bonded insulation for space shuttle LH2 tanks, is reported. Emphasis was placed on an insulation system capable of reentry and multiple reuse in the shuttle environment. The optimized manufacturing parameters associated with each element of the composite are established and the results, showing successful completion of subscale system evaluation tests using the shuttle flight environmental requirements, are given.

The observation of ultrafast excited-state dynamical evolution in B800- partially or completely released LH2 of Rhodobacter sphaeroides 601 at room temperature.

PubMed

Liu, Weimin; Liu, Yuan; Yan, Yongli; Liu, Kangjun; Guo, Lijun; Xu, Chunhe; Qian, Shixiong

2006-04-01

Photodynamics of two kinds of peripheral antenna complexes (LH2 of Rhodobacter sphaeroides, native LH2 (RS601) and B800-released LH2 where B800-BChls were partially or completely removed with different pH treatments), were studied using femtosecond pump-probe technique at different laser wavelengths. The obtained results for these samples with different B800/B850 ratios demonstrated that under the excitation around B800 nm, the photoabsorption and photobleaching dynamics were caused by the direct excitation of upper excitonic levels of B850 and excited state of B800 pigments, respectively. Furthermore, the removal of B800 pigments had little effect on the energy transfer processes of B850 interband/intraband transfer.

Investigation of lightweight designs and materials for LO2 and LH2 propellant tanks for space vehicles, phase 2 and phase 3

NASA Technical Reports Server (NTRS)

1976-01-01

Full size Tug LO2 and LH2 tank configurations were defined, based on selected tank geometries. These configurations were then locally modeled for computer stress analysis. A large subscale test tank, representing the selected Tug LO2 tank, was designed and analyzed. This tank was fabricated using procedures which represented production operations. An evaluation test program was outlined and a test procedure defined. The necessary test hardware was also fabricated.

Stark absorption spectroscopy on the carotenoids bound to B800-820 and B800-850 type LH2 complexes from a purple photosynthetic bacterium, Phaeospirillum molischianum strain DSM120.

PubMed

Horibe, Tomoko; Qian, Pu; Hunter, C Neil; Hashimoto, Hideki

2015-04-15

Stark absorption spectroscopy was applied to clarify the structural differences between carotenoids bound to the B800-820 and B800-850 LH2 complexes from a purple photosynthetic bacterium Phaeospirillum (Phs.) molischianum DSM120. The former complex is produced when the bacteria are grown under stressed conditions of low temperature and dim light. These two LH2 complexes bind carotenoids with similar composition, 10% lycopene and 80% rhodopin, each with the same number of conjugated CC double bonds (n=11). Quantitative classical and semi-quantum chemical analyses of Stark absorption spectra recorded in the carotenoid absorption region reveal that the absolute values of the difference dipole moments |Δμ| have substantial differences (2 [D/f]) for carotenoids bound to either B800-820 or B800-850 complexes. The origin of this striking difference in the |Δμ| values was analyzed using the X-ray crystal structure of the B800-850 LH2 complex from Phs. molischianum DSM119. Semi-empirical molecular orbital calculations predict structural deformations of the major carotenoid, rhodopin, bound within the B800-820 complex. We propose that simultaneous rotations around neighboring CC and CC bonds account for the differences in the 2 [D/f] of the |Δμ| value. The plausible position of the rotation is postulated to be located around C21-C24 bonds of rhodopin. Copyright © 2014 Elsevier Inc. All rights reserved.

Functional characteristics of spirilloxanthin and keto-bearing Analogues in light-harvesting LH2 complexes from Rhodobacter sphaeroides with a genetically modified carotenoid synthesis pathway.

PubMed

Niedzwiedzki, Dariusz M; Dilbeck, Preston L; Tang, Qun; Mothersole, David J; Martin, Elizabeth C; Bocian, David F; Holten, Dewey; Hunter, C Neil

2015-01-01

Light-harvesting 2 (LH2) complexes from a genetically modified strain of the purple photosynthetic bacterium Rhodobacter (Rba.) sphaeroides were studied using static and ultrafast optical methods and resonance Raman spectroscopy. Carotenoid synthesis in the Rba. sphaeroides strain was engineered to redirect carotenoid production away from spheroidene into the spirilloxanthin synthesis pathway. The strain assembles LH2 antennas with substantial amounts of spirilloxanthin (total double-bond conjugation length N=13) if grown anaerobically and of keto-bearing long-chain analogs [2-ketoanhydrorhodovibrin (N=13), 2-ketospirilloxanthin (N=14) and 2,2'-diketospirilloxanthin (N=15)] if grown semi-aerobically (with ratios that depend on growth conditions). We present the photophysical, electronic, and vibrational properties of these carotenoids, both isolated in organic media and assembled within LH2 complexes. Measurements of excited-state energy transfer to the array of excitonically coupled bacteriochlorophyll a molecules (B850) show that the mean lifetime of the first singlet excited state (S1) of the long-chain (N≥13) carotenoids does not change appreciably between organic media and the protein environment. In each case, the S1 state appears to lie lower in energy than that of B850. The energy-transfer yield is ~0.4 in LH2 (from the strain grown aerobically or semi-aerobically), which is less than half that achieved for LH2 that contains short-chain (N≤11) analogues. Collectively, the results suggest that the S1 excited state of the long-chain (N≥13) carotenoids participates little if at all in carotenoid-to-BChl a energy transfer, which occurs predominantly via the carotenoid S2 excited state in these antennas. Copyright © 2015 Elsevier B.V. All rights reserved.

Spectroscopic and Thermodynamic Characterization of the Metal-Binding Sites in the LH1-RC Complex from Thermophilic Photosynthetic Bacterium Thermochromatium tepidum.

PubMed

Kimura, Yukihiro; Yura, Yuki; Hayashi, Yusuke; Li, Yong; Onoda, Moe; Yu, Long-Jiang; Wang-Otomo, Zheng-Yu; Ohno, Takashi

2016-12-15

The light-harvesting 1 reaction center (LH1-RC) complex from thermophilic photosynthetic bacterium Thermochromatium (Tch.) tepidum exhibits enhanced thermostability and an unusual LH1 Q y transition, both induced by Ca 2+ binding. In this study, metal-binding sites and metal-protein interactions in the LH1-RC complexes from wild-type (B915) and biosynthetically Sr 2+ -substituted (B888) Tch. tepidum were investigated by isothermal titration calorimetry (ITC), atomic absorption (AA), and attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopies. The ITC measurements revealed stoichiometric ratios of approximately 1:1 for binding of Ca 2+ , Sr 2+ , or Ba 2+ to the LH1 αβ-subunit, indicating the presence of 16 binding sites in both B915 and B888. The AA analysis provided direct evidence for Ca 2+ and Sr 2+ binding to B915 and B888, respectively, in their purified states. Metal-binding experiments supported that Ca 2+ and Sr 2+ (or Ba 2+ ) competitively associate with the binding sites in both species. The ATR-FTIR difference spectra upon Ca 2+ depletion and Sr 2+ substitution demonstrated that dissociation and binding of Ca 2+ are predominantly responsible for metal-dependent conformational changes of B915 and B888. The present results are largely compatible with the recent structural evidence that another binding site for Sr 2+ (or Ba 2+ ) exists in the vicinity of the Ca 2+ -binding site, a part of which is shared in both metal-binding sites.

Evaluation of biological activities of new LH-RH antagonists (T-series) in male and female rats.

PubMed

Pinski, J; Yano, T; Janaky, T; Nagy, A; Juhasz, A; Bokser, L; Groot, K; Schally, A V

1993-01-01

A series of new highly potent LH-RH antagonists (T-series) has been synthesized in our laboratory. Among these analogs, antagonists [Ac-D-Nal(2), D-Phe(4Cl)2, D-Pal(3)3, D-Lys(A2pr(Car)2)6, D-Ala10]LH-RH (T-140); [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Lys(A2pr(Ac)2)6, D-Ala10]LH-RH (T-148); [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Lys(A2pr(For)2)6, D-Ala10]LH-RH (T-151) and [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Lys(A2bu(For)2)6, D-Ala10]LH-RH (T-159) were the most powerful. Antagonists T-140, T-148 and T-151 produced a complete blockade of ovulation in normal cycling rats at a dose of 1.5 micrograms/rat and antagonist T-159 at a dose of only 0.75 micrograms/rat. The inhibitory effects of compounds T-148, T-151 and T-159 on gonadotropin and sex steroid secretion were investigated in male and female rats. To determine their effect on LH levels in castrated male and ovariectomized female rats, T-148, T-151 and T-159 were injected subcutaneously in doses of 0.625 and 2.5 micrograms/rat. Blood samples were taken at different intervals for 48 h. All three compounds at either dose caused a significant (P < 0.01) decrease in LH levels for more than 6 h. Significant (P < 0.01) inhibition of LH lasted for more than 24 h following a dose of 2.5 micrograms sc of all 3 antagonists in both male and female rats. Serum FSH levels were also suppressed significantly for more than 48 h in castrated male rats by all three antagonists at a dose of 5 micrograms/rat sc.(ABSTRACT TRUNCATED AT 250 WORDS)

LENGTH-HETEROGENEITY POLYMERASE CHAIN REACTION (LH-PCR) AS AN INDICATOR OF STREAM SANITARY AND ECOLOGICAL CONDITION: OPTIMAL SAMPLE SIZE AND HOLDING CONDITIONS

EPA Science Inventory

The use of coliform plate count data to assess stream sanitary and ecological condition is limited by the need to store samples at 4oC and analyze them within a 24-hour period. We are testing LH-PCR as an alternative tool to assess the bacterial load of streams, offering a cost ...

Bifurcation analysis and dimension reduction of a predator-prey model for the L-H transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dam, Magnus; Brøns, Morten; Juul Rasmussen, Jens

2013-10-15

The L-H transition denotes a shift to an improved confinement state of a toroidal plasma in a fusion reactor. A model of the L-H transition is required to simulate the time dependence of tokamak discharges that include the L-H transition. A 3-ODE predator-prey type model of the L-H transition is investigated with bifurcation theory of dynamical systems. The analysis shows that the model contains three types of transitions: an oscillating transition, a sharp transition with hysteresis, and a smooth transition. The model is recognized as a slow-fast system. A reduced 2-ODE model consisting of the full model restricted to themore » flow on the critical manifold is found to contain all the same dynamics as the full model. This means that all the dynamics in the system is essentially 2-dimensional, and a minimal model of the L-H transition could be a 2-ODE model.« less

Integrative approach to produce hydrogen and polyhydroxybutyrate from biowaste using defined bacterial cultures.

PubMed

Patel, Sanjay K S; Kumar, Prasun; Singh, Mamtesh; Lee, Jung-Kul; Kalia, Vipin C

2015-01-01

Biological production of hydrogen (H2) and polyhydroxybutyrate (PHB) from pea-shell slurry (PSS) was investigated using defined mixed culture (MMC4, composed of Enterobacter, Proteus, Bacillus spp.). Under batch culture, 19.0LH2/kg of PSS (total solid, TS, 2%w/v) was evolved. Using effluent from the H2 producing stage, Bacillus cereus EGU43 could produce 12.4% (w/w) PHB. Dilutions of PSS hydrolysate containing glucose (0.5%, w/v) resulted in 45-75LH2/kg TS fed and 19.1% (w/w) of PHB content. Under continuous culture, MMC4 immobilized on coconut coir (CC) lead to an H2 yield of 54L/kg TS fed and a PHB content of 64.7% (w/w). An improvement of 2- and 3.7-fold in H2 and PHB yields were achieved in comparison to control. This integrative approach using defined set of bacterial strains can prove effective in producing biomolecules from biowastes. Copyright © 2014. Published by Elsevier Ltd.

Preliminary base heating environments for a generalized ALS LO2/LH2 launch vehicle, appendix 1 and 2

NASA Technical Reports Server (NTRS)

Bender, Robert L.; Reardon, John E.

1989-01-01

A secondary objective of contract NAS8-39141 is to provide base heating assessments, as required, to support Advanced Launch System (ALS) preliminary launch vehicle and propulsion system design studies. The ALS propulsion systems integration working group meeting (No. 3) recently completed in San Diego, California, focused attention on the need for base heating environment determination to provide preliminary requirements for LO2/LH2 propulsion systems currently being considered for ALS. We were requested to provide these environments for a range of possible propellant mixture and nozzle area ratios. Base heating environments can only be determined as a function of altitude when the engine operating conditions and vehicle base region geometry (engine arrangement) are known. If time dependent environments are needed to assess thermal loads, a trajectory must also be provided. These parameters are not fixed at this time since the ALS configurations and propulsion operating conditions are varied and continue to be studied by Phase B contractors. Therefore, for this study, a generalized LO2/LH2 system was selected along with a vehicle configuration consisting of a seven-engine booster and a three-engine core. MSFC provided guidance for the selection. We also selected a limited number of body points on the booster and core vehicles and engines for the environment estimates. Environments at these locations are representative of maximum heating conditions in the base region and are provided as a function of altitude only. Guidelines and assumptions for this assessment, methodology for determining the environments, and preliminary results are provided in this technical note. Refinements in the environments will be provided as the ALS design matures.

Increasing LH Pulsatility in Women With Hypothalamic Amenorrhoea Using Intravenous Infusion of Kisspeptin-54

PubMed Central

Jayasena, Channa N.; Abbara, Ali; Veldhuis, Johannes D.; Comninos, Alexander N.; Ratnasabapathy, Risheka; De Silva, Akila; Nijher, Gurjinder M. K.; Ganiyu-Dada, Zainab; Mehta, Amrish; Todd, Catriona; Ghatei, Mohammad A.; Bloom, Stephen R.

2014-01-01

Background: Hypothalamic amenorrhea (HA) is the one of the most common causes of period loss in women of reproductive age and is associated with deficient LH pulsatility. High-dose kisspeptin-54 acutely stimulates LH secretion in women with HA, but chronic administration causes desensitization. GnRH has paradoxical effects on reproductive activity; we therefore hypothesized that a dose-dependent therapeutic window exists within which kisspeptin treatment restores the GnRH/LH pulsatility in women with HA. Aim: The aim of the study was to determine whether constant iv infusion of kisspeptin-54 temporarily increases pulsatile LH secretion in women with HA. Methods: Five patients with HA each underwent six assessments of LH pulsatility. Single-blinded continuous iv infusion of vehicle or kisspeptin-54 (0.01, 0.03, 0.10, 0.30, or 1.00 nmol/kg/h) was administered. The LH pulses were detected using blinded deconvolution. Results: Kisspeptin increased LH pulsatility in all patients with HA, with peak responses observed at different doses in each patient. The mean peak number of pulses during infusion of kisspeptin-54 was 3-fold higher when compared with vehicle (number of LH pulses per 8 h: 1.6 ± 0.4, vehicle; 5.0 ± 0.5, kisspeptin-54, P < .01 vs vehicle). The mean peak LH pulse secretory mass during kisspeptin-54 was 6-fold higher when compared with vehicle (LH pulse secretory mass in international units per liter: 3.92 ± 2.31, vehicle; 23.44 ± 12.59, kisspeptin-54; P < .05 vs vehicle). Conclusions: Kisspeptin-54 infusion temporarily increases LH pulsatility in women with HA. Furthermore, we have determined the dose range within which kisspeptin-54 treatment increases basal and pulsatile LH secretion in women with HA. This work provides a basis for studying the potential of kisspeptin-based therapies to treat women with HA. PMID:24517142

[The lh-rh-test in men with fertility disorders (author's transl)].

PubMed

Krause, W; Höbel, W

1976-11-01

89 mal patients with fertility disorders underwent a test with 50 mug synthetic LH-RH. The basal levels of FSH and LH are elevated in patients with azoospermia, with testicular atrophy, varicocele and Klinefelters syndrome. They increase with age. After stimulation with LH-RH the highest relative peaks (maximal value divided by control value) of LH are seen younger patients, in those with varicocele, and oligozoospermia. The FSH-values do not differ significantly between these groups. Low relative peaks of LH are seen in older patients. In Klinefelter's syndrome the relative peaks of FSH and LH are significantly lowered.

Determination of the topological shape of integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria in the detergent solution by small-angle X-ray scattering.

PubMed

Hong, Xinguo; Weng, Yu-Xiang; Li, Ming

2004-02-01

The topological shape of the integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria Rhodobacter spheroides 2.4.1 in detergent solution has been determined from synchrotron small-angle X-ray scattering data using direct curve-fitting by the ellipsoid, ab initio shape determination methods of simulated annealing algorithm and multipole expansion, respectively. The results indicate that the LH2 protein in aqueous solution is encapsulated by a monolayered detergent shell. The detergent-stabilized structure has the shape of an oblate plate, with a thickness of 40 A, a long axis of 110 A, and a short axis of 85 A. After correction for the detergent shell, the shape of the LH2 core is also an oblate plate with a height of 40 A, a long axis of 80 A, and a short axis of 55 A. In contrast to the cylindrical crystal structure with a height of 40 A and a diameter of 68 A, the molecular shape of the LH2 complex in detergent solution clearly deviates from the ringlike crystal structure, with an eccentricity found to be 0.59-consistent with the result of single molecular spectroscopy study of the isolated single LH2 molecules.

Determination of the Topological Shape of Integral Membrane Protein Light-Harvesting Complex LH2 from Photosynthetic Bacteria in the Detergent Solution by Small-Angle X-Ray Scattering

PubMed Central

Hong, Xinguo; Weng, Yu-Xiang; Li, Ming

2004-01-01

The topological shape of the integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria Rhodobacter spheroides 2.4.1 in detergent solution has been determined from synchrotron small-angle X-ray scattering data using direct curve-fitting by the ellipsoid, ab initio shape determination methods of simulated annealing algorithm and multipole expansion, respectively. The results indicate that the LH2 protein in aqueous solution is encapsulated by a monolayered detergent shell. The detergent-stabilized structure has the shape of an oblate plate, with a thickness of 40 Å, a long axis of 110 Å, and a short axis of 85 Å . After correction for the detergent shell, the shape of the LH2 core is also an oblate plate with a height of 40 Å, a long axis of 80 Å, and a short axis of 55 Å. In contrast to the cylindrical crystal structure with a height of 40 Å and a diameter of 68 Å, the molecular shape of the LH2 complex in detergent solution clearly deviates from the ringlike crystal structure, with an eccentricity found to be 0.59—consistent with the result of single molecular spectroscopy study of the isolated single LH2 molecules. PMID:14747343

Patterned biofilm formation reveals a mechanism for structural heterogeneity in bacterial biofilms.

PubMed

Gu, Huan; Hou, Shuyu; Yongyat, Chanokpon; De Tore, Suzanne; Ren, Dacheng

2013-09-03

Bacterial biofilms are ubiquitous and are the major cause of chronic infections in humans and persistent biofouling in industry. Despite the significance of bacterial biofilms, the mechanism of biofilm formation and associated drug tolerance is still not fully understood. A major challenge in biofilm research is the intrinsic heterogeneity in the biofilm structure, which leads to temporal and spatial variation in cell density and gene expression. To understand and control such structural heterogeneity, surfaces with patterned functional alkanthiols were used in this study to obtain Escherichia coli cell clusters with systematically varied cluster size and distance between clusters. The results from quantitative imaging analysis revealed an interesting phenomenon in which multicellular connections can be formed between cell clusters depending on the size of interacting clusters and the distance between them. In addition, significant differences in patterned biofilm formation were observed between wild-type E. coli RP437 and some of its isogenic mutants, indicating that certain cellular and genetic factors are involved in interactions among cell clusters. In particular, autoinducer-2-mediated quorum sensing was found to be important. Collectively, these results provide missing information that links cell-to-cell signaling and interaction among cell clusters to the structural organization of bacterial biofilms.

Close-in characteristics of LH2/LOX reactions

NASA Technical Reports Server (NTRS)

Riehl, W. A.; Ullian, L. J.

1985-01-01

In deriving shock overpressures from space vehicles employing LH2 and LOX, separate methods of analyses and prediction are recommended, as a function of the distance. Three methods of treatment are recommended. For the Far Field - where the expected shock overpressure is less than 40 psi (lambda = 5) - use the classical PYRO approach to determine TNT yield, and employ classical ordnance (Kingery) curve to obtain the overall value. For the Close-In Range, a suggested limit is 3D, or a zone from a distance of three times the tank diameter to the tank wall. Rather than estimate a specific distance from the center of explosion to the target, it is only necessary to estimate whether this could be within one, two, or three diameters away from the wall; i.e., in the 1, 2, or 3D zone. Then assess whether mixing mode is by the PYRO CBGS (spill) mode or CBM (internal mixing) mode. From the zone and mixing mode, the probability of attaining various shock overpressures is determined from the plots provided herein. For the transition zone, between 40 psi and the 3D distance, it is tentatively recommended that both of the preceding methods be used, and to be conservative, the higher resulting value be used.

X-Rays from the Location of the Double-humped Transient ASASSN-15lh

NASA Astrophysics Data System (ADS)

Margutti, R.; Metzger, B. D.; Chornock, R.; Milisavljevic, D.; Berger, E.; Blanchard, P. K.; Guidorzi, C.; Migliori, G.; Kamble, A.; Lunnan, R.; Nicholl, M.; Coppejans, D. L.; Dall'Osso, S.; Drout, M. R.; Perna, R.; Sbarufatti, B.

2017-02-01

We present the detection of persistent soft X-ray radiation with {L}x˜ {10}41-1042 erg s-1 at the location of the extremely luminous, double-humped transient ASASSN-15lh as revealed by Chandra and Swift. We interpret this finding in the context of observations from our multiwavelength campaign, which revealed the presence of weak narrow nebular emission features from the host-galaxy nucleus and clear differences with respect to superluminous supernova optical spectra. Significant UV flux variability on short timescales detected at the time of the rebrightening disfavors the shock interaction scenario as the source of energy powering the long-lived UV emission, while deep radio limits exclude the presence of relativistic jets propagating into a low-density environment. We propose a model where the extreme luminosity and double-peaked temporal structure of ASASSN-15lh is powered by a central source of ionizing radiation that produces a sudden change in the ejecta opacity at later times. As a result, UV radiation can more easily escape, producing the second bump in the light curve. We discuss different interpretations for the intrinsic nature of the ionizing source. We conclude that, if the X-ray source is physically associated with the optical-UV transient, then ASASSN-15lh most likely represents the tidal disruption of a main-sequence star by the most massive spinning black hole detected to date. In this case, ASASSN-15lh and similar events discovered in the future would constitute the most direct probes of very massive, dormant, spinning, supermassive black holes in galaxies. Future monitoring of the X-rays may allow us to distinguish between the supernova hypothesis and the hypothesis of a tidal disruption event.

X-Rays from the Location of the Double-humped Transient ASASSN-15lh

PubMed Central

Margutti, R.; Metzger, B. D.; Chornock, R.; Milisavljevic, D.; Berger, E.; Blanchard, P. K.; Guidorzi, C.; Migliori, G.; Kamble, A.; Lunnan, R.; Nicholl, M.; Coppejans, D. L.; Dall’Osso, S.; Drout, M. R.; Perna, R.; Sbarufatti, B.

2017-01-01

We present the detection of persistent soft X-ray radiation with Lx ~ 1041–1042 erg s−1 at the location of the extremely luminous, double-humped transient ASASSN-15lh as revealed by Chandra and Swift. We interpret this finding in the context of observations from our multiwavelength campaign, which revealed the presence of weak narrow nebular emission features from the host-galaxy nucleus and clear differences with respect to superluminous supernova optical spectra. Significant UV flux variability on short timescales detected at the time of the rebrightening disfavors the shock interaction scenario as the source of energy powering the long-lived UV emission, while deep radio limits exclude the presence of relativistic jets propagating into a low-density environment. We propose a model where the extreme luminosity and double-peaked temporal structure of ASASSN-15lh is powered by a central source of ionizing radiation that produces a sudden change in the ejecta opacity at later times. As a result, UV radiation can more easily escape, producing the second bump in the light curve. We discuss different interpretations for the intrinsic nature of the ionizing source. We conclude that, if the X-ray source is physically associated with the optical–UV transient, then ASASSN-15lh most likely represents the tidal disruption of a main-sequence star by the most massive spinning black hole detected to date. In this case, ASASSN-15lh and similar events discovered in the future would constitute the most direct probes of very massive, dormant, spinning, supermassive black holes in galaxies. Future monitoring of the X-rays may allow us to distinguish between the supernova hypothesis and the hypothesis of a tidal disruption event. PMID:28966348

Evaluation of bacterial communities belonging to natural whey starters for Grana Padano cheese by length heterogeneity-PCR.

PubMed

Lazzi, C; Rossetti, L; Zago, M; Neviani, E; Giraffa, G

2004-01-01

To detect bacteria present in controlled dairy ecosystems with defined composition by length-heterogeneity (LH)-PCR. LH-PCR allows to distinguish different organisms on the basis of natural variations in the length of 16S rRNA gene sequences. LH-PCR was applied to depict population structure of the lactic acid bacteria (LAB) species recoverable from Grana Padano cheese whey starters. Typical bacterial species present in the LAB community were evidenced and well discriminated. Small differences in species composition, e.g. the frequent finding of Streptococcus thermophilus and the constant presence of thermophilic lactobacilli (Lactobacillus helveticus, Lact. delbrueckii subsp. lactis/bulgaricus and Lact. fermentum) were reliably highlighted. Specificity of LH-PCR was confirmed by species-specific PCR from total DNA of the cultures. LH-PCR is a useful tool to monitor microbial composition and population dynamics in dairy starter cultures. When present, non-dominant bacterial species present in the whey starters, such as Strep. thermophilus, can easily be visualized and characterized without isolating and cultivating single strains. A similar approach can be applied to more complex dairy ecosystems such as milk or cheese curd. Community members and differences in population structure of controlled dairy ecosystems such as whey starters for hard cheeses can be evaluated and compared in a relative easy, fast, reliable and highly reproducible way.

Developmental programming: Prenatal BPA treatment disrupts timing of LH surge and ovarian follicular wave dynamics in adult sheep

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veiga-Lopez, A.; Beckett, E.M.; Abi Salloum, B.

Developmental exposure to BPA adversely affects reproductive function. In sheep, prenatal BPA treatment induces reproductive neuroendocrine defects, manifested as LH excess and dampened LH surge and perturbs early ovarian gene expression. In this study we hypothesized that prenatal BPA treatment will also disrupt ovarian follicular dynamics. Pregnant sheep were treated from days 30 to 90 of gestation with 3 different BPA doses (0.05, 0.5, or 5 mg/kg BW/day). All female offspring were estrus synchronized and transrectal ultrasonography was performed daily for 22 days to monitor ovarian follicular and corpora lutea dynamics. Blood samples were collected to assess preovulatory hormonal changesmore » and luteal progesterone dynamics. Statistical analysis revealed that the time interval between the estradiol rise and the preovulatory LH surge was shortened in the BPA-treated females. None of the three BPA doses had an effect on corpora lutea, progestogenic cycles, and mean number or duration of ovulatory and non-ovulatory follicles. However, differences in follicular count trajectories were evident in all three follicular size classes (2–3 mm, 4–5 mm, and ≥ 6 mm) of prenatal BPA-treated animals compared to controls. Number of follicular waves tended also to be more variable in the prenatal BPA-treated groups ranging from 2 to 5 follicular waves per cycle, while this was restricted to 3 to 4 waves in control females. These changes in ovarian follicular dynamics coupled with defects in time interval between estradiol rise and preovulatory LH release are likely to lead to subfertility in prenatal BPA-treated females. - Highlights: • Prenatal BPA shortens interval between estradiol rise and preovulatory LH surge. • Prenatal BPA affects follicular count trajectory and follicular wave occurrence. • Prenatal BPA does not affect ovulatory rate and progesterone dynamics.« less

Impact of the lipid bilayer on energy transfer kinetics in the photosynthetic protein LH2† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc04814a

PubMed Central

Ogren, John I.; Tong, Ashley L.; Gordon, Samuel C.; Chenu, Aurélia; Lu, Yue; Blankenship, Robert E.; Cao, Jianshu

2018-01-01

Photosynthetic purple bacteria convert solar energy to chemical energy with near unity quantum efficiency. The light-harvesting process begins with absorption of solar energy by an antenna protein called Light-Harvesting Complex 2 (LH2). Energy is subsequently transferred within LH2 and then through a network of additional light-harvesting proteins to a central location, termed the reaction center, where charge separation occurs. The energy transfer dynamics of LH2 are highly sensitive to intermolecular distances and relative organizations. As a result, minor structural perturbations can cause significant changes in these dynamics. Previous experiments have primarily been performed in two ways. One uses non-native samples where LH2 is solubilized in detergent, which can alter protein structure. The other uses complex membranes that contain multiple proteins within a large lipid area, which make it difficult to identify and distinguish perturbations caused by protein–protein interactions and lipid–protein interactions. Here, we introduce the use of the biochemical platform of model membrane discs to study the energy transfer dynamics of photosynthetic light-harvesting complexes in a near-native environment. We incorporate a single LH2 from Rhodobacter sphaeroides into membrane discs that provide a spectroscopically amenable sample in an environment more physiological than detergent but less complex than traditional membranes. This provides a simplified system to understand an individual protein and how the lipid–protein interaction affects energy transfer dynamics. We compare the energy transfer rates of detergent-solubilized LH2 with those of LH2 in membrane discs using transient absorption spectroscopy and transient absorption anisotropy. For one key energy transfer step in LH2, we observe a 30% enhancement of the rate for LH2 in membrane discs compared to that in detergent. Based on experimental results and theoretical modeling, we attribute this difference

Spacecraft attitude impacts on COLD-SAT non-vacuum jacketed LH2 supply tank thermal performance

NASA Technical Reports Server (NTRS)

Arif, Hugh

1990-01-01

The Cryogenic On-Orbit Liquid Depot - Storage, Acquisition and Transfer (COLD-SAT) spacecraft will be launched into low earth orbit to perform fluid management experiments on the behavior of subcritical liquid hydrogen (LH2). For determining the optimum on-orbit attitude for the COLD-SAT satellite, a comparative analytical study was performed to determine the thermal impacts of spacecraft attitude on the performance of the COLD-SAT non-vacuum jacketed LH2 supply tank. Tank thermal performance was quantitied by total conductive and radiative heat leakage into the pressure vessel due to the absorbed solar, earth albedo and infra-red on-orbit fluxes, and also by the uniformity of the variation of this leakage on the vessel surface area. Geometric and thermal analysis math models were developed for the spacecraft and the tank as part of this analysis, based on their individual thermal/structural designs. Two quasi-inertial spacecraft attitudes were investigated and their effects on the tank performance compared. The results are one of the criteria by which the spacecraft orientation in orbit was selected for the in-house NASA Lewis Research Center design.

Spacecraft attitude impacts on COLD-SAT non-vacuum jacketed LH2 supply tank thermal performance

NASA Technical Reports Server (NTRS)

Arif, Hugh

1990-01-01

The Cryogenic On-Orbit Liquid Depot - Storage, Acquisition and Transfer (COLD-SAT) spacecraft will be launched into low earth orbit to perform fluid management experiments on the behavior of subcritical liquid hydrogen (LH2). For determining the optimum on-orbit attitude for the COLD-SAT satellite, a comparative analytical study was performed to determine the thermal impacts of spacecraft attitude on the performance of the COLD-SAT non-vacuum jacketed LH2 supply tank. Tank thermal performance was quantified by total conductive and radiative heat leakage into the pressure vessel due to the absorbed solar, earth albedo and infra-red on-orbit fluxes, and also by the uniformity of the variation of this leakage on the vessel surface area. Geometric and thermal analysis math models were developed for the spacecraft and the tank as part of this analysis, based on their individual thermal/structural designs. Two quasi-inertial spacecraft attitudes were investigated and their effects on the tank performance compared. The results are one of the criteria by which the spacecraft orientation in orbit was selected for the in-house NASA Lewis Research Center design.

The NMDA Receptor Subunit NR2b: Effects on LH Release and GnRH Gene Expression in Young and Middle-aged Female Rats, with Modulation by Estradiol

PubMed Central

Maffucci, Jacqueline A.; Walker, Deena M.; Ikegami, Aiko; Woller, Michael J.; Gore, Andrea C.

2008-01-01

The loss of reproductive capacity during aging involves changes in the neural regulation of the hypothalamic gonadotropin-releasing hormone (GnRH) neurons controlling reproduction. This neuronal circuitry includes glutamate receptors on GnRH neurons. Previously, we reported an increase in the expression of the NR2b subunit protein of the NMDA receptor on GnRH neurons in middle-aged compared to young female rats. Here, we examined the functional implications of the NR2b subunit on the onset of reproductive aging, using an NR2b-specific antagonist ifenprodil. Young (3–5 mos.) and middle-aged (10–13 mos.) female rats were ovariectomized (OVX), 17β-estradiol (E2) or vehicle (cholesterol) treated, and implanted with a jugular catheter. Serial blood sampling was undertaken every 10 minutes for 4 hours, with ifenprodil (10mg/kg) or vehicle injected (i.p.) after one hour of baseline sampling. The pulsatile release of pituitary LH and levels of GnRH mRNA in hypothalamus were quantified as indices of the reproductive axis. Our results showed effects of ifenprodil on both endpoints. In OVX rats given cholesterol, neither age nor ifenprodil had any effects on LH release. In E2-treated rats, aging was associated with significant decreases in pulsatile LH release. Additionally, ifenprodil stimulated parameters of pulsatile LH release in both young and middle-aged animals. Ifenprodil had few effects on GnRH mRNA; the only significant effect of ifenprodil was found in the middle-aged, cholesterol group. Together, these findings support a role for the NR2b subunit of the NMDAR in GnRH/LH regulation. Because most of these effects were exhibited on pituitary LH release in the absence of a concomitant change in GnRH gene expression, it is likely that NMDA receptors containing the NR2b subunit plays a role in GnRH-induced LH release, independent of de novo GnRH gene expression. PMID:18025808

Transient absorption study of two-photon excitation mechanism in the LH2 complex from purple bacterium Rhodobacter sphaeroides.

PubMed

Stepanenko, Ilya; Kompanetz, Viktor; Makhneva, Zoya; Chekalin, Sergey; Moskalenko, Andrei; Razjivin, Andrei

2012-03-08

The mechanism of two-photon excitation of a peripheral light-harvesting complex LH2 (B800-850) from purple bacterium Rhodobacter sphaeroides was explained on the basis of femtosecond transient absorption data. Fast bleaching of the B850 absorption band was measured under two-photon excitation by 1350 nm femtosecond pulses, showing fast subpicosecond arrival of excitation energy to B850 circular aggregates. Any spectral changes connected with the B800 absorption band of B800-BChl molecules were absent. A similar picture was observed under one-photon excitation of the LH2 complex by 675 nm femtosecond pulses. We believe these effects may be attributed to direct excitation of high-energy excitonic states of a B850 circular aggregate or its vibrational manifold in accordance with the model of Abe [Chem. Phys. 2001, 264, 355-363].

Influence of hormonal control on LH pulsatility and secretion in women with classical congenital adrenal hyperplasia.

PubMed

Bachelot, Anne; Chakhtoura, Zeina; Plu-Bureau, Geneviève; Coudert, Mathieu; Coussieu, Christiane; Badachi, Yasmina; Dulon, Jérome; Charbit, Beny; Touraine, Philippe

2012-10-01

Women with classical congenital adrenal hyperplasia (CAH) exhibit reduced fertility due to several factors including anovulation. This has been attributed to a disturbed gonadotropic axis as in polycystic ovary syndrome (PCOS), but there is no precise evaluation. Our aim was to evaluate the gonadotropic axis and LH pulsatility patterns and to determine factor(s) that could account for the potential abnormality of LH pulsatility. Case/control study. Sixteen CAH women (11 with the salt-wasting form and five with the simple virilizing form), aged from 18 to 40 years, and 16 age-matched women, with regular menstrual cycles (28 ± 3 days), were included. LH pulse patterns over 6 h were determined in patients and controls. No differences were observed between patients and controls in terms of mean LH levels, LH pulse amplitude, or LH frequency. In CAH patients, LH pulsatility patterns were heterogeneous, leading us to perform a clustering analysis of LH data, resulting in a two-cluster partition. Patients in cluster 1 had similar LH pulsatility patterns to the controls. Patients in cluster 2 had: lower LH pulse amplitude and frequency and presented menstrual cycle disturbances more frequently; higher 17-OH progesterone, testosterone, progesterone, and androstenedione levels; and lower FSH levels. LH pulsatility may be normal in CAH women well controlled by hormonal treatment. Undertreatment is responsible for hypogonadotropic hypogonadism, with low LH pulse levels and frequency, but not PCOS. Suppression of progesterone and androgen concentrations during the follicular phase of the menstrual cycle should be a major objective in these patients.

Mechanism of degradation of LH-RH and neurotensin by synaptosomal peptidases.

PubMed

McDermott, J R; Smith, A I; Dodd, P R; Hardy, J A; Edwardson, J A

1983-01-01

The products of degradation of LH-RH and neurotensin by synaptosomes isolated from rat hypothalamus and cortex have been identified. LH-RH is cleaved at Tyr5-Gly6 and Pro9-Gly10 giving rise to LH-RH (1-5), LH-RH (6-10) and LH-RH (1-9). Neurotensin is cleaved at Arg8-Arg9, Pro10-Tyr11 and Ile12-Leu13, giving neurotensin (1-8), neurotensin (1-10), neurotensin (1-12) and neurotensin (9-13) as major products. While most of the peptidase activity is localized in the cytoplasmic fraction, a small but significant proportion is membrane bound. For LH-RH, the specificity of the membrane-bound activity is similar to that in the cytosol fraction; for neurotensin, the membrane fraction preferentially gives rise to the (1-10) and (1-11) peptides. The most potent inhibitors of the LH-RH and neurotensin degrading enzymes in synaptosomes are heavy metal ions (mercury and copper), p-chloromercuribenzoate and 1,10 phenanthroline.

The Mystery of ASASSN-15lh

NASA Astrophysics Data System (ADS)

Fruchter, Andrew; van Velzen, Sjoert

2018-01-01

ASASSN-15lh is the most luminous optical transient ever detected; yet, its nature is unclear. It was first thought to be a supernova. However, its host shows little sign of star formation, and the transient has remained a hot thermal source for two years, making a supernova origin seem less likely. Alternatively, ASSASN-15lh may be a flare caused by the tidal disruption of a star by a supermassive black hole. However, this model is also far from an easy fit. The luminosity of the host’s bulge implies a black hole mass so large that a star would almost certainly be swallowed before disrupted, unless the the black hole is spinning near maximally. Furthermore, the double-humped shape of the light curve seen in the UV is highly unusual for a tidal disruption flare (TDF). Here we present reanalysis of HST archival images of the ASASSN-15lh and its host. We show that the host has highly unusual morphological features that are only reasonably explained by a substantial merger. A merger can greatly increase the rate of TDFs through perturbation of stellar orbits, the introduction and/or formation of new stars near the central black hole, or even the addition of a second massive black hole to the core of the galaxy. The disturbed morphology of the host thus supports the TDF explanation of ASASSN-15lh.

Developmental programming: Prenatal BPA treatment disrupts timing of LH surge and ovarian follicular wave dynamics in adult sheep

PubMed Central

Veiga-Lopez, A; Beckett, EM; Abi Salloum, B; Ye, W; Padmanabhan, V

2014-01-01

Developmental exposure to BPA adversely affects reproductive function. In sheep, prenatal BPA treatment induces reproductive neuroendocrine defects, manifested as LH excess and dampened LH surge and perturbs early ovarian gene expression. In this study we hypothesized that prenatal BPA treatment will also disrupt ovarian follicular dynamics. Pregnant sheep were treated from days 30 to 90 of gestation with 3 different BPA doses (0.05, 0.5, or 5 mg/kg BW/day). All female offspring were estrus synchronized and transrectal ultrasonography was performed daily for 22 days to monitor ovarian follicular and corpora lutea dynamics. Blood samples were collected to assess hormonal preovulatory changes and luteal progesterone dynamics. Statistical analysis revealed that the time interval between the estradiol rise and the preovulatory LH surge was shortened in the BPA-treated females. None of the three BPA doses had an effect on corpora lutea, progestogenic cycles, and mean or duration of ovulatory and non-ovulatory follicles. However, differences in follicular count trajectories were evident in all three follicular size classes (2–3 mm, 4–5 mm, and ≥ 6 mm) of prenatal BPA-treated animals compared to controls. Number of follicular waves tended also to be more variable in the prenatal BPA-treated groups ranging from 2 to 5 follicular waves per cycle, while this was restricted to 3 to 4 waves in control females. These changes in ovarian follicular dynamics coupled with defects in time interval between estradiol rise and preovulatory LH release are likely to lead to subfertility in prenatal BPA-treated females. PMID:24923655

The Use of rLH, HMG and hCG in Controlled Ovarian Stimulation for Assisted Reproductive Technologies

DTIC Science & Technology

2012-11-21

express CYP17, the gene encoding for the critical enzyme in the conversion of progesterone and pregnenalone to androgens (3). Conversely, granulosa...2. Potential mechanisms of exogenous LH benefit in ART There are theoretical benefits of the use of exogenous LH for the oocyte and the endometrium...folliculogenesis when administered with FSH (85). rLH has potential advantages over the LH activity in hMG in that there is less risk of protein contamination and

Probing energy transfer events in the light harvesting complex 2 (LH2) of Rhodobacter sphaeroides with two-dimensional spectroscopy.

PubMed

Fidler, Andrew F; Singh, Ved P; Long, Phillip D; Dahlberg, Peter D; Engel, Gregory S

2013-10-21

Excitation energy transfer events in the photosynthetic light harvesting complex 2 (LH2) of Rhodobacter sphaeroides are investigated with polarization controlled two-dimensional electronic spectroscopy. A spectrally broadened pulse allows simultaneous measurement of the energy transfer within and between the two absorption bands at 800 nm and 850 nm. The phased all-parallel polarization two-dimensional spectra resolve the initial events of energy transfer by separating the intra-band and inter-band relaxation processes across the two-dimensional map. The internal dynamics of the 800 nm region of the spectra are resolved as a cross peak that grows in on an ultrafast time scale, reflecting energy transfer between higher lying excitations of the B850 chromophores into the B800 states. We utilize a polarization sequence designed to highlight the initial excited state dynamics which uncovers an ultrafast transfer component between the two bands that was not observed in the all-parallel polarization data. We attribute the ultrafast transfer component to energy transfer from higher energy exciton states to lower energy states of the strongly coupled B850 chromophores. Connecting the spectroscopic signature to the molecular structure, we reveal multiple relaxation pathways including a cyclic transfer of energy between the two rings of the complex.

Analysis and design of insulation systems for LH2-fueled aircraft

NASA Technical Reports Server (NTRS)

Cunnington, G. R., Jr.

1979-01-01

An analytical program was conducted to evaluate the performance of 15 potential insulations for the fuel tanks of a subsonic LH2-fueled transport aircraft intended for airline service in the 1990-1995 time period. As a result, two candidate insulation systems are proposed for subsonic transport aircraft applications. Both candidates are judged to be the optimum available and should meet the design requirements. However, because of the long-life cyclic nature of the application and the cost sensitivity of airline operations, an experimental tank/insulation development or proof-of-concept program is recommended. This program should be carried out with a nearly full-scale system which would be subjected to the cyclic thermal and mechanical inputs anticipated in aircraft service.

Betacarotene supplementation increases ovulation rate without an increment in LH secretion in cyclic goats.

PubMed

Meza-Herrera, Cesar A; Vargas-Beltran, Fermin; Vergara-Hernandez, Hector P; Macias-Cruz, Ulises; Avendaño-Reyes, Leonel; Rodriguez-Martinez, Rafael; Arellano-Rodriguez, Gerardo; Veliz-Deras, Francisco G

2013-03-01

This study aimed to evaluate the effects of betacarotene (BC) supplementation on ovulation rate (OR) and luteinizing hormone (LH) secretion in adult goats during the breeding season. Additionally, total ovarian activity (TOA) comprising the total number of ultrasonographically detectable antral follicles (AF) and corpora lutea (OR) was also assessed. In early October, adult goats [n=22, 3.5 years of age, 7/8 Sannen-Alpine; 26°N, 103°W at 1117m.a.s.l.] were randomly assigned to: (i) BC group (BCG), orally supplemented with 50mg of BC/goat/day [n=10; live weight (LW)=45.9±2.0kg, body condition score (BCS; range: 0-emaciated to 5-obese)=3.0±0.1], and (ii) control group (CONT) [n=12; LW=46.2±2.0kg, BCS=3.0±0.1]. All animals received a basal diet of alfalfa hay, corn silage and corn grain, with free access to water and mineral salts. The whole experimental period spanned 34 days before and 17 days after ovulation. On day 23 of the experiment, estrus was synchronized with progestin-releasing intravaginal sponges; 36h prior to estrus, an intensive blood sampling (every 15min for 6h) was performed to determine mean LH concentrations, pulsatility (LH-PULSE) and area under the curve (LH-AUC) for serial LH concentrations. Afterwards, by the end of the luteal phase (i.e., 17 days after the onset of estrus), an ultrasonographic scanning was performed to evaluate OR and TOA [AF+OR]. The average LW and BCS did not differ (p>0.05) during the experimental period. BC-supplemented goats showed an increase in OR (3.4±0.2 versus 2.8±0.2; p<0.05) and exhibited lower (p<0.05) serum LH concentrations, LH-AUC and LH-PULSE compared to CONT. A positive correlation was recorded between OR and LW (r(2)=0.42, p<0.05) and BCS (r(2)=0.47, p<0.05). In addition, AF (5.0±0.6 versus 3.4±0.6) and TOA (8.4±0.6 versus 6.2±0.6) were greater (p<0.05) in the BC-supplemented group than CONT. Supplementation with BC enhanced ovarian follicular development and ovulation rate in adult female goats

LOX/LH2 propulsion system for launch vehicle upper stage, test results

NASA Technical Reports Server (NTRS)

Ikeda, T.; Imachi, U.; Yuzawa, Y.; Kondo, Y.; Miyoshi, K.; Higashino, K.

1984-01-01

The test results of small LOX/LH2 engines for two propulsion systems, a pump fed system and a pressure fed system are reported. The pump fed system has the advantages of higher performances and higher mass fraction. The pressure fed system has the advantages of higher reliability and relative simplicity. Adoption of these cryogenic propulsion systems for upper stage of launch vehicle increases the payload capability with low cost. The 1,000 kg thrust class engine was selected for this cryogenic stage. A thrust chamber assembly for the pressure fed propulsion system was tested. It is indicated that it has good performance to meet system requirements.

Atomistic non-adiabatic dynamics of the LH2 complex with a GPU-accelerated ab initio exciton model

DOE PAGES

Sisto, Aaron; Stross, Clem; van der Kamp, Marc W.; ...

2017-03-28

We recently outlined an efficient multi-tiered parallel ab initio excitonic framework that utilizes time dependent density functional theory (TDDFT) to calculate ground and excited state energies and gradients of large supramolecular complexes in atomistic detail – enabling us to undertake non-adiabatic simulations which explicitly account for the coupled anharmonic vibrational motion of all the constituent atoms in a supramolecular system. Here we apply that framework to the 27 coupled bacterio-chlorophyll-a chromophores which make up the LH2 complex, using it to compute an on-the-fly nonadiabatic surface-hopping (SH) trajectory of electronically excited LH2. Part one of this article is focussed on calibratingmore » our ab initio exciton Hamiltonian using two key parameters: a shift δ, which corrects for the error in TDDFT vertical excitation energies; and an effective dielectric constant ε, which describes the average screening of the transition-dipole coupling between chromophores. Using snapshots obtained from equilibrium molecular dynamics simulations (MD) of LH2, we tune the values of both δ and ε through fitting to the thermally broadened experimental absorption spectrum, giving a linear absorption spectrum that agrees reasonably well with experiment. In part two of this article, we construct a time-resolved picture of the coupled vibrational and excitation energy transfer (EET) dynamics in the sub-picosecond regime following photo-excitation. Assuming Franck–Condon excitation of a narrow eigenstate band centred at 800 nm, we use surface hopping to follow a single nonadiabatic dynamics trajectory within the full eigenstate manifold. Consistent with experimental data, this trajectory gives timescales for B800→B850 population transfer (τ B800→B850) between 650–1050 fs, and B800 population decay (τ 800→) between 10–50 fs. The dynamical picture that emerges is one of rapidly fluctuating LH2 eigenstates that are delocalized over multiple

Atomistic non-adiabatic dynamics of the LH2 complex with a GPU-accelerated ab initio exciton model.

PubMed

Sisto, Aaron; Stross, Clem; van der Kamp, Marc W; O'Connor, Michael; McIntosh-Smith, Simon; Johnson, Graham T; Hohenstein, Edward G; Manby, Fred R; Glowacki, David R; Martinez, Todd J

2017-06-14

We recently outlined an efficient multi-tiered parallel ab initio excitonic framework that utilizes time dependent density functional theory (TDDFT) to calculate ground and excited state energies and gradients of large supramolecular complexes in atomistic detail - enabling us to undertake non-adiabatic simulations which explicitly account for the coupled anharmonic vibrational motion of all the constituent atoms in a supramolecular system. Here we apply that framework to the 27 coupled bacterio-chlorophyll-a chromophores which make up the LH2 complex, using it to compute an on-the-fly nonadiabatic surface-hopping (SH) trajectory of electronically excited LH2. Part one of this article is focussed on calibrating our ab initio exciton Hamiltonian using two key parameters: a shift δ, which corrects for the error in TDDFT vertical excitation energies; and an effective dielectric constant ε, which describes the average screening of the transition-dipole coupling between chromophores. Using snapshots obtained from equilibrium molecular dynamics simulations (MD) of LH2, we tune the values of both δ and ε through fitting to the thermally broadened experimental absorption spectrum, giving a linear absorption spectrum that agrees reasonably well with experiment. In part two of this article, we construct a time-resolved picture of the coupled vibrational and excitation energy transfer (EET) dynamics in the sub-picosecond regime following photo-excitation. Assuming Franck-Condon excitation of a narrow eigenstate band centred at 800 nm, we use surface hopping to follow a single nonadiabatic dynamics trajectory within the full eigenstate manifold. Consistent with experimental data, this trajectory gives timescales for B800→B850 population transfer (τ B800→B850 ) between 650-1050 fs, and B800 population decay (τ 800→ ) between 10-50 fs. The dynamical picture that emerges is one of rapidly fluctuating LH2 eigenstates that are delocalized over multiple chromophores and

Bacterial diskospondylitis in juvenile mink from 2 Ontario mink farms.

PubMed

Martínez, Jorge; Vidaña, Beatriz; Cruz-Arambulo, Robert; Slavic, Durda; Tapscott, Brian; Brash, Marina L

2013-09-01

Nine juvenile mink with hind-limb paresis/paralysis from 2 Ontario farms were submitted for necropsy. Diagnostic tests revealed spinal compression and severe thoracic diskospondylitis with intralesional Gram-positive coccoid bacterial colonies. Streptococcus canis, Streptococcus dysgalactiae subsp. equisimilis, and hemolytic Staphylococcus spp. were isolated from vertebral lesions.

Computation provides chemical insight into the diverse hydride NMR chemical shifts of [Ru(NHC)4(L)H]0/+ species (NHC = N-heterocyclic carbene; L = vacant, H2, N2, CO, MeCN, O2, P4, SO2, H-, F- and Cl-) and their [Ru(R2PCH2CH2PR2)2(L)H]+ congeners.

PubMed

Häller, L Jonas L; Mas-Marzá, Elena; Cybulski, Mateusz K; Sanguramath, Rajashekharayya A; Macgregor, Stuart A; Mahon, Mary F; Raynaud, Christophe; Russell, Christopher A; Whittlesey, Michael K

2017-02-28

Relativistic density functional theory calculations, both with and without the effects of spin-orbit coupling, have been employed to model hydride NMR chemical shifts for a series of [Ru(NHC) 4 (L)H] 0/+ species (NHC = N-heterocyclic carbene; L = vacant, H 2 , N 2 , CO, MeCN, O 2 , P 4 , SO 2 , H - , F - and Cl - ), as well as selected phosphine analogues [Ru(R 2 PCH 2 CH 2 PR 2 ) 2 (L)H] + (R = i Pr, Cy; L = vacant, O 2 ). Inclusion of spin-orbit coupling provides good agreement with the experimental data. For the NHC systems large variations in hydride chemical shift are shown to arise from the paramagnetic term, with high net shielding (L = vacant, Cl - , F - ) being reinforced by the contribution from spin-orbit coupling. Natural chemical shift analysis highlights the major orbital contributions to the paramagnetic term and rationalizes trends via changes in the energies of the occupied Ru d π orbitals and the unoccupied σ* Ru-H orbital. In [Ru(NHC) 4 (η 2 -O 2 )H] + a δ-interaction with the O 2 ligand results in a low-lying LUMO of d π character. As a result this orbital can no longer contribute to the paramagnetic shielding, but instead provides additional deshielding via overlap with the remaining (occupied) d π orbital under the L z angular momentum operator. These two effects account for the unusual hydride chemical shift of +4.8 ppm observed experimentally for this species. Calculations reproduce hydride chemical shift data observed for [Ru( i Pr 2 PCH 2 CH 2 P i Pr 2 ) 2 (η 2 -O 2 )H] + (δ = -6.2 ppm) and [Ru(R 2 PCH 2 CH 2 PR 2 ) 2 H] + (ca. -32 ppm, R = i Pr, Cy). For the latter, the presence of a weak agostic interaction trans to the hydride ligand is significant, as in its absence (R = Me) calculations predict a chemical shift of -41 ppm, similar to the [Ru(NHC) 4 H] + analogues. Depending on the strength of the agostic interaction a variation of up to 18 ppm in hydride chemical shift is possible and this factor (that is not necessarily

Energy exchange dynamics across L-H transitions in NSTX

NASA Astrophysics Data System (ADS)

Diallo, A.; Banerjee, S.; Zweben, S. J.; Stoltzfus-Dueck, T.

2017-06-01

We studied the energy exchange dynamics across the low-to-high-confinement (L-H) transition in NSTX discharges using the gas-puff imaging (GPI) diagnostic. The investigation focused on the energy exchange between flows and turbulence to help clarify the mechanism of the L-H transition. We applied this study to three types of heating schemes, including a total of 17 shots from the NSTX 2010 campaign run. Results show that the edge fluctuation characteristics (fluctuation levels, radial and poloidal correlation lengths) measured using GPI do not vary just prior to the H-mode transition, but change after the transition. Using a velocimetry approach (orthogonal-dynamics programming), velocity fields of a 24× 30 cm GPI view during the L-H transition were obtained with good spatial (˜1 cm) and temporal (˜2.5 μs) resolutions. Analysis using these velocity fields shows that the production term is systematically negative just prior to the L-H transition, indicating a transfer from mean flows to turbulence, which is inconsistent with the predator-prey paradigm. Moreover, the inferred absolute value of the production term is two orders of magnitude too small to explain the observed rapid L-H transition. These discrepancies are further reinforced by consideration of the ratio between the kinetic energy in the mean flow to the thermal free energy, which is estimated to be much less than 1, suggesting again that the turbulence depletion mechanism may not play an important role in the transition to the H-mode. Although the Reynolds work therefore appears to be too small to directly deplete the turbulent free energy reservoir, order-of-magnitude analysis shows that the Reynolds stress may still make a non-negligible contribution to the observed poloidal flows.

Bacterial diskospondylitis in juvenile mink from 2 Ontario mink farms

PubMed Central

Martínez, Jorge; Vidaña, Beatriz; Cruz-Arambulo, Robert; Slavic, Durda; Tapscott, Brian; Brash, Marina L.

2013-01-01

Nine juvenile mink with hind-limb paresis/paralysis from 2 Ontario farms were submitted for necropsy. Diagnostic tests revealed spinal compression and severe thoracic diskospondylitis with intralesional Gram-positive coccoid bacterial colonies. Streptococcus canis, Streptococcus dysgalactiae subsp. equisimilis, and hemolytic Staphylococcus spp. were isolated from vertebral lesions. PMID:24155490

Dephosphorylation and inactivation of NPR2 guanylyl cyclase in granulosa cells contributes to the LH-induced decrease in cGMP that causes resumption of meiosis in rat oocytes

PubMed Central

Egbert, Jeremy R.; Shuhaibar, Leia C.; Edmund, Aaron B.; Van Helden, Dusty A.; Robinson, Jerid W.; Uliasz, Tracy F.; Baena, Valentina; Geerts, Andreas; Wunder, Frank; Potter, Lincoln R.; Jaffe, Laurinda A.

2014-01-01

In mammals, the meiotic cell cycle of oocytes starts during embryogenesis and then pauses. Much later, in preparation for fertilization, oocytes within preovulatory follicles resume meiosis in response to luteinizing hormone (LH). Before LH stimulation, the arrest is maintained by diffusion of cyclic (c)GMP into the oocyte from the surrounding granulosa cells, where it is produced by the guanylyl cyclase natriuretic peptide receptor 2 (NPR2). LH rapidly reduces the production of cGMP, but how this occurs is unknown. Here, using rat follicles, we show that within 10 min, LH signaling causes dephosphorylation and inactivation of NPR2 through a process that requires the activity of phosphoprotein phosphatase (PPP)-family members. The rapid dephosphorylation of NPR2 is accompanied by a rapid phosphorylation of the cGMP phosphodiesterase PDE5, an enzyme whose activity is increased upon phosphorylation. Later, levels of the NPR2 agonist C-type natriuretic peptide decrease in the follicle, and these sequential events contribute to the decrease in cGMP that causes meiosis to resume in the oocyte. PMID:25183874

Development of advanced materials composites for use as insulations for LH2 tanks

NASA Technical Reports Server (NTRS)

Lemons, C. R.; Watts, C. R.; Salmassy, O. K.

1972-01-01

A study of internal insulation materials and fabrication processes for space shuttle LH2 tanks is reported. Emphasis was placed on an insulation system capable of reentry and multiple reuse in the Shuttle environment. Results are given on the optimization and manufacturing process scale-up of a 3D fiberreinforced foam insulation, BX-251-3D, derived from the Saturn S-4B internal insulation. It is shown that BX-251-3D can be satisfactorily installed in large-scale tanks under conditions that will permit a significant cost saving over the existing S-4B technology.

Thermal test of the insulation structure for LH 2 tank by using the large experimental apparatus

NASA Astrophysics Data System (ADS)

Kamiya, S.; Onishi, K.; Konshima, N.; Nishigaki, K.

Conceptual designs of large mass LH 2 (liquid hydrogen) storage systems, whose capacity is 50,000 m3, have been studied in the Japanese hydrogen project, World Energy Network (WE-NET) [K. Fukuda, in: WE-NET Hydrogen Energy Symposium, 1999, P1-P41]. This study has concluded that their thermal insulation structures for the huge LH 2 tanks should be developed. Their actual insulation structures comprise not only the insulation material but also reinforced members and joints. To evaluate their thermal performance correctly, a large test specimen including reinforced members and joints will be necessary. After verifying the thermal performance of a developed large experimental apparatus [S. Kamiya, Cryogenics 40 (1) (2000) 35] for measuring the thermal conductance of various insulation structures, we tested two specimens, a vacuum multilayer insulation (MLI) with a glass fiber reinforced plastic (GFRP) support and a vacuum solid insulation (microtherm ®) with joints. The thermal background test for verifying the thermal design of the experimental apparatus showed that the background heat leak is 0.1 W, small enough to satisfy apparatus performance requirement. The thermal conductance measurements of specimens also showed that thermal heat fluxes of MLI with a GFRP support and microtherm ® are 8 and 5.4 W/m2, respectively.

Bacterial Communities in Women with Bacterial Vaginosis: High Resolution Phylogenetic Analyses Reveal Relationships of Microbiota to Clinical Criteria

PubMed Central

Srinivasan, Sujatha; Hoffman, Noah G.; Morgan, Martin T.; Matsen, Frederick A.; Fiedler, Tina L.; Hall, Robert W.; Ross, Frederick J.; McCoy, Connor O.; Bumgarner, Roger; Marrazzo, Jeanne M.; Fredricks, David N.

2012-01-01

Background Bacterial vaginosis (BV) is a common condition that is associated with numerous adverse health outcomes and is characterized by poorly understood changes in the vaginal microbiota. We sought to describe the composition and diversity of the vaginal bacterial biota in women with BV using deep sequencing of the 16S rRNA gene coupled with species-level taxonomic identification. We investigated the associations between the presence of individual bacterial species and clinical diagnostic characteristics of BV. Methodology/Principal Findings Broad-range 16S rRNA gene PCR and pyrosequencing were performed on vaginal swabs from 220 women with and without BV. BV was assessed by Amsel’s clinical criteria and confirmed by Gram stain. Taxonomic classification was performed using phylogenetic placement tools that assigned 99% of query sequence reads to the species level. Women with BV had heterogeneous vaginal bacterial communities that were usually not dominated by a single taxon. In the absence of BV, vaginal bacterial communities were dominated by either Lactobacillus crispatus or Lactobacillus iners. Leptotrichia amnionii and Eggerthella sp. were the only two BV-associated bacteria (BVABs) significantly associated with each of the four Amsel’s criteria. Co-occurrence analysis revealed the presence of several sub-groups of BVABs suggesting metabolic co-dependencies. Greater abundance of several BVABs was observed in Black women without BV. Conclusions/Significance The human vaginal bacterial biota is heterogeneous and marked by greater species richness and diversity in women with BV; no species is universally present. Different bacterial species have different associations with the four clinical criteria, which may account for discrepancies often observed between Amsel and Nugent (Gram stain) diagnostic criteria. Several BVABs exhibited race-dependent prevalence when analyzed in separate groups by BV status which may contribute to increased incidence of BV in

Hybrid Composites for LH2 Fuel Tank Structure

NASA Technical Reports Server (NTRS)

Grimsley, Brian W.; Cano, Roberto J.; Johnston, Norman J.; Loos, Alfred C.; McMahon, William M.

2001-01-01

The application of lightweight carbon fiber reinforced plastics (CFRP) as structure for cryogenic fuel tanks is critical to the success of the next generation of Reusable Launch Vehicles (RLV). The recent failure of the X-33 composite fuel tank occurred in part due to microcracking of the polymer matrix, which allowed cryogen to permeate through the inner skin to the honeycomb core. As part of an approach to solve these problems, NASA Langley Research Center (LaRC) and Marshall Space Flight Center (MSFC) are working to develop and investigate polymer films that will act as a barrier to the permeation of LH2 through the composite laminate. In this study two commercially available films and eleven novel LaRC films were tested in an existing cryogenics laboratory at MSFC to determine the permeance of argon at room temperature. Several of these films were introduced as a layer in the composite to form an interleaved, or hybrid, composite to determine the effects on permeability. In addition, the effects of the interleaved layer thickness, number, and location on the mechanical properties of the composite laminate were investigated. In this initial screening process, several of the films were found to exhibit lower permeability to argon than the composite panels tested.

Insight into the structure of photosynthetic LH2 aggregate from spectroscopy simulations.

PubMed

Rancova, Olga; Sulskus, Juozas; Abramavicius, Darius

2012-07-12

Using the electrostatic model of intermolecular interactions, we obtain the Frenkel exciton Hamiltonian parameters for the chlorophyll Qy band of a photosynthetic peripheral light harvesting complex LH2 of a purple bacteria Rhodopseudomonas acidophila from structural data. The intermolecular couplings are mostly determined by the chlorophyll relative positions, whereas the molecular transition energies are determined by the background charge distribution of the whole complex. The protonation pattern of titratable residues is used as a tunable parameter. By studying several protonation state scenarios for distinct protein groups and comparing the simulated absorption and circular dichroism spectra to experiment, we determine the most probable configuration of the protonation states of various side groups of the protein.

Urinary excretion of LH and testosterone from male rats during exposure to increased gravity: post-spaceflight and centrifugation

NASA Technical Reports Server (NTRS)

Ortiz, R. M.; Wade, C. E.; Morey-Holton, E.

2000-01-01

A dissociation between plasma luteinizing hormone (LH) and testosterone (T) appears to exist during exposure to altered gravity. The pulsatile nature of LH release and the diurnal variability of T secretion may mask or bias the effects of altered gravity on the pituitary-gonadal axis when analyzing plasma concentrations. Therefore, we examined the relationship between the excretion of urinary LH and T in male Sprague-Dawley rats during exposure to increased gravity upon return to Earth following a 14-day spaceflight (n = 6) and by 12 days of centrifugation at 2g (n = 8). Excreted LH and T were elevated on the first 3 days postflight. Excreted T was elevated between Days 1 and 8 of centrifugation; however, excreted LH was reduced on Days 2 and 3 compared with control animals. Excreted LH and T were significantly correlated (R = 0.731 and 0.706, respectively) in postspaceflight and centrifuged animals. Correlation curves had similar slopes (0.0213 and 0.023, respectively), but different y-intercepts (-1.43 and 3.32, respectively). The sustained increase in excreted T during centrifugation suggests that the pituitary-gonadal axis in postspaceflight animals may adapt quicker to increased gravity. The upward shift in the correlation curve exhibited by the centrifuged animals suggests that the sensitivity of LH-induced T release is increased in these animals. The previous dissociation between plasma LH and T during altered gravity was not observed in the present study in which excreted LH and T were measured.

The structure and thermal motion of the B800-850 LH2 complex from Rps.acidophila at 2.0A resolution and 100K: new structural features and functionally relevant motions.

PubMed

Papiz, Miroslav Z; Prince, Steve M; Howard, Tina; Cogdell, Richard J; Isaacs, Neil W

2003-03-07

The structure at 100K of integral membrane light-harvesting complex II (LH2) from Rhodopseudomonas acidophila strain 10050 has been refined to 2.0A resolution. The electron density has been significantly improved, compared to the 2.5A resolution map, by high resolution data, cryo-cooling and translation, libration, screw (TLS) refinement. The electron density reveals a second carotenoid molecule, the last five C-terminal residues of the alpha-chain and a carboxy modified alpha-Met1 which forms the ligand of the B800 bacteriochlorophyll. TLS refinement has enabled the characterisation of displacements between molecules in the complex. B850 bacteriochlorophyll molecules are arranged in a ring of 18 pigments composed of nine approximate dimers. These pigments are strongly coupled and at their equilibrium positions the excited state dipole interaction energies, within and between dimers, are approximately 370cm(-1) and 280cm(-1), respectively. This difference in coupling energy is similar in magnitude to changes in interaction energies arising from the pigment displacements described by TLS tensors. The displacements appear to be non-random in nature and appear to be designed to optimise the modulation of pigment energy interactions. This is the first time that LH2 pigment displacements have been quantified experimentally. The calculated energy changes indicate that there may be significant contributions to inter-pigment energy interactions from molecular displacements and these may be of importance to photosynthetic energy transfer.

Transient dwarfism and hypogonadism in mice lacking Otx1 reveal prepubescent stage-specific control of pituitary levels of GH, FSH and LH.

PubMed

Acampora, D; Mazan, S; Tuorto, F; Avantaggiato, V; Tremblay, J J; Lazzaro, D; di Carlo, A; Mariano, A; Macchia, P E; Corte, G; Macchia, V; Drouin, J; Brûlet, P; Simeone, A

1998-04-01

Genetic and molecular approaches have enabled the identification of regulatory genes critically involved in determining cell types in the pituitary gland and/or in the hypothalamus. Here we report that Otx1, a homeobox-containing gene of the Otx gene family, is postnatally transcribed and translated in the pituitary gland. Cell culture experiments indicate that Otx1 may activate transcription of the growth hormone (GH), follicle-stimulating hormone (betaFSH), luteinizing hormone (betaLH) and alpha-glycoprotein subunit (alphaGSU) genes. Analysis of Otx1 null mice indicates that, at the prepubescent stage, they exhibit transient dwarfism and hypogonadism due to low levels of pituitary GH, FSH and LH hormones which, in turn, dramatically affect downstream molecular and organ targets. Nevertheless, Otx1-/- mice gradually recover from most of these abnormalities, showing normal levels of pituitary hormones with restored growth and gonadal function at 4 months of age. Expression patterns of related hypothalamic and pituitary cell type restricted genes, growth hormone releasing hormone (GRH), gonadotropin releasing hormone (GnRH) and their pituitary receptors (GRHR and GnRHR) suggest that, in Otx1-/- mice, hypothalamic and pituitary cells of the somatotropic and gonadotropic lineages appear unaltered and that the ability to synthesize GH, FSH and LH, rather than the number of cells producing these hormones, is affected. Our data indicate that Otx1 is a new pituitary transcription factor involved at the prepubescent stage in the control of GH, FSH and LH hormone levels and suggest that a complex regulatory mechanism might exist to control the physiological need for pituitary hormones at specific postnatal stages.

LH/hCG-Receptor Expression May Have a Negative Prognostic Value in Low-Risk Endometrial Cancer.

PubMed

Noci, Ivo; Sorbi, Flavia; Mannini, Luca; Projetto, Elisabetta; Pillozzi, Serena; Ghizzoni, Viola; Lottini, Tiziano; Moncini, Daniela; Baroni, Gianna; Mungai, Francesco; Arcangeli, Annarosa; Fambrini, Massimiliano

2016-01-01

A 51 year-old woman was diagnosed with endometrial cancer (EC) and underwent surgical staging. Pathological evaluation showed a 2 cm × 1 cm G2 endometrioid EC with a 30% myometrial deep invasion (FIGO Stage 1A). The patient was classified as low risk of recurrence, and no adjuvant treatment was offered. Six months after surgery, the patient developed an early vescico-vaginal recurrence, and chemotherapy treatment was started. Few months later, a subsequent involvement of vaginal wall, ileum, and omentum was detected, and the patient underwent second surgery. LH/hCG-receptor (LH/hCG-R) expression has been previously reported to be associated with an invasive phenotype in EC cells. Moreover, in a preclinical mouse model of EC behaves as a prometastatic molecular device. We analyzed the expression level of LH/hCG-R in cancer specimens collected during surgeries. Molecular and immunohistochemical analyses showed a strong expression of both mRNA and protein for LH/hCG-R in all specimens. LH/hCG-R expression may be assessed together with other clinicopathological parameters in order to better predict the risk of recurrence in low-risk EC patients. Further clinical trials are warranted in order to validate LH/hCG-R as biomarker in EC.

Fluorescence-excitation and emission spectra from LH2 antenna complexes of Rhodopseudomonas acidophila as a function of the sample preparation conditions.

PubMed

Kunz, Ralf; Timpmann, Kõu; Southall, June; Cogdell, Richard J; Köhler, Jürgen; Freiberg, Arvi

2013-10-10

The high sensitivity of optical spectra of pigment-protein complexes to temperature and pressure is well known. In the present study, we have demonstrated the significant influence of the environments commonly used in bulk and single-molecule spectroscopic studies at low temperatures on the LH2 photosynthetic antenna complex from Rhodopseudomonas acidophila. A transfer of this LH2 complex from a bulk-buffer solution into a spin-coated polymer film results in a 189 cm(-1) blue shift of the B850 excitonic absorption band at 5 K. Within the molecular exciton model, the origin of this shift could be disentangled into three parts, namely to an increase of the local site energies, a contraction of the exciton band, and a decrease of the displacement energy.

Weak evidence of bright light effects on human LH and FSH.

PubMed

Kripke, Daniel F; Elliott, Jeffrey A; Youngstedt, Shawn D; Parry, Barbara L; Hauger, Richard L; Rex, Katharine M

2010-05-11

Most mammals are seasonal breeders whose gonads grow to anticipate reproduction in the spring and summer. As day length increases, secretion increases for two gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH). This response is largely controlled by light. Light effects on gonadotropins are mediated through effects on the suprachiasmatic nucleus and responses of the circadian system. There is some evidence that seasonal breeding in humans is regulated by similar mechanisms, and that light stimulates LH secretion, but primate responses seem complex. To gain further information on effects of bright light on LH and FSH secretion in humans, we analyzed urine samples collected in three experiments conducted for other goals. First, volunteers ages 18-30 years and 60-75 commenced an ultra-short 90-min sleep-wake cycle, during which they were exposed to 3000 lux light for 3 hours at balanced times of day, repeated for 3 days. Urine samples were assayed to explore any LH phase response curve. Second, depressed participants 60-79 years of age were treated with bright light or dim placebo light for 28 days, with measurements of urinary LH and FSH before and after treatment. Third, women of ages 20-45 years with premenstrual dysphoric disorder (PMDD) were treated to one 3-hour exposure of morning light, measuring LH and FSH in urine before and after the treatments. Two of the three studies showed significant increases in LH after light treatment, and FSH also tended to increase, but there were no significant contrasts with parallel placebo treatments and no significant time-of-day treatment effects. These results gave some support for the hypothesis that bright light may augment LH secretion. Longer-duration studies may be needed to clarify the effects of light on human LH and FSH.

Pulsatile LH secretion and ovarian follicular wave emergence and growth in anestrous ewes.

PubMed

Seekallu, Srinivas V; Barrett, David M W; Toosi, Behzad M; Clarke, Kelsey; Ewen, Kirk A; Duggavathi, Rajesha; Davies, Kate L; Pattullo, Kim M; Bagu, Edward T; Rawlings, Norman C

2010-10-01

The objective of this study was to determine if pulsatile LH secretion was needed for ovarian follicular wave emergence and growth in the anestrous ewe. In Experiment 1, ewes were either large or small (10 x 0.47 or 5 x 0.47 cm, respectively; n = 5/group) sc implants releasing estradiol-17 beta for 10 d (Day 0 = day of implant insertion), to suppress pulsed LH secretion, but not FSH secretion. Five sham-operated control ewes received no implants. In Experiment 2, 12 ewes received large estradiol-releasing implants for 12 d (Day 0 = day of implant insertion); six were given GnRH (200 ng IV) every 4 h for the last 6 d that the implants were in place (to reinitiate pulsed LH secretion) whereas six Control ewes were given saline. Ovarian ultrasonography and blood sampling were done daily; blood samples were also taken every 12 min for 6 h on Days 5 and 9, and on Days 6 and 12 of the treatment period in Experiments 1 and 2, respectively. Treatment with estradiol blocked pulsatile LH secretion (P < 0.001). In Experiment 1, implant treatment halted follicular wave emergence between Days 2 and 10. In Experiment 2, follicular waves were suppressed during treatment with estradiol, but resumed following GnRH treatment. In both experiments, the range of peaks in serum FSH concentrations that preceded and triggered follicular wave emergence was almost the same as control ewes and those given estradiol implants alone or with GnRH; mean concentrations did not differ (P < 0.05). We concluded that some level of pulsatile LH secretion was required for the emergence of follicular waves that were triggered by peaks in serum FSH concentrations in the anestrous ewe. (c) 2010 Elsevier Inc. All rights reserved.

LH2 Target Design & Position Survey Techniques for the MUSE experiment for Precise Proton Radius Measurement

NASA Astrophysics Data System (ADS)

Le Pottier, Luc; Roy, Pryiashee; Lorenzon, Wolfgang; Raymond, Richard; Steinberg, Noah; Rossi de La Fuente, Erick; MUSE (MUon proton Scattering Experiment) Collaboration

2017-09-01

The proton radius puzzle is a currently unresolved problem which has intrigued the scientific community, dealing with a 7 σ discrepancy between the proton radii determined from muonic hydrogen spectroscopy and electron scattering measurements. The MUon Scattering Experiment (MUSE) aims to resolve this puzzle by performing the first simultaneous elastic scattering measurements of both electrons and muons on the proton, which will allow the comparison of the radii from the two interactions with reduced systematic uncertainties. The data from this experiment is expected to provide the best test of lepton universality to date. The experiment will take place at the Paul Scherrer Institute in Switzerland in 2018. An essential component of the experiment is a liquid hydrogen (LH2) cryotarget system. Our group at the University of Michigan is responsible for the design, fabrication and installation of this system. Here we present our LH2 target cell design and fabrication techniques for successful operation at 20 K and 1 atm, and our computer vision-based target position survey system which will determine the position of the target, installed inside a vacuum chamber, with 0.01 mm or better precision at the height of the liquid hydrogen target and along the beam direction during the experiment.

Neurokinin-3 Receptor Activation in the Retrochiasmatic Area is Essential for the Full Preovulatory LH Surge in Ewes

PubMed Central

Porter, Katrina L.; Hileman, Stanley M.; Hardy, Steven L.; Nestor, Casey C; Lehman, Michael N.; Goodman, Robert L.

2014-01-01

Neurokinin B (NKB) is essential for human reproduction and has been shown to stimulate LH secretion in several species, including sheep. Ewes express the neurokinin-3 receptor (NK3R) in the retrochiasmatic area (RCh) and there is one report that placement of senktide, an NK3R agonist, therein stimulates LH secretion that resembles an LH surge in ewes. In this study, we first confirmed that local administration of senktide to the RCh produced a surge-like increase in LH secretion, and then tested the effects of this agonist in two other areas implicated in the control of LH secretion and where NK3R is found in high abundance: the preoptic area (POA) and arcuate nucleus (ARC). Bilateral microimplants containing senktide induced a dramatic surge-like increase in LH when given in the POA similar to that seen with RCh treatment. In contrast, senktide treatment in the ARC resulted in a much smaller, but significant, increase in LH concentrations suggestive of an effect on tonic secretion. The possible role of POA and RCh NK3R activation in the LH surge was next tested by treating ewes with SB222200, an NK3R antagonist, in each area during an E2-induced LH surge. SB222200 in the RCh, but not in the POA, reduced LH surge amplitude by about 40% compared to controls, indicating that NK3R activation in the former region is essential for full expression of the preovulatory LH surge. Based on these data, we propose that NKB actions in the RCh are an important component of the preovulatory LH surge in ewes. PMID:25040132

Single-shot ultrabroadband two-dimensional electronic spectroscopy of the light-harvesting complex LH2.

PubMed

Harel, Elad; Long, Phillip D; Engel, Gregory S

2011-05-01

Here we present two-dimensional (2D) electronic spectra of the light-harvesting complex LH2 from purple bacteria using coherent pulses with bandwidth of over 100 nm FWHM. This broadband excitation and detection has allowed the simultaneous capture of both the B800 and B850 bands using a single light source. We demonstrate that one laser pulse is sufficient to capture the entire 2D electronic spectrum with a high signal-to-noise ratio. At a waiting time of 800 fs, we observe population transfer from the B800 to B850 band as manifested by a prominent cross peak. These results will enable observation of the dynamics of biological systems across both ultrafast (<1 ps) and slower (>1 ms) timescales simultaneously.

Kisspeptin Antagonists Reveal Kisspeptin 1 and Kisspeptin 2 Differential Regulation of Reproduction in the Teleost, Morone saxatilis.

PubMed

Zmora, Nilli; Stubblefield, John David; Wong, Ten-Tsao; Levavi-Sivan, Berta; Millar, Robert Peter; Zohar, Yonathan

2015-09-01

The importance of kisspeptin in regulating vertebrate reproduction has been well established, but the exact mechanism continues to unfold. Unlike mammals, many lower vertebrates possess a dual kisspeptin system, Kiss1 and Kiss2. To decipher the roles of the kisspeptins in fish, we identified two potential kisspeptin antagonists, pep 234 and pep 359, by screening analogs for their ability to inactivate striped bass Kiss1 and Kiss2 receptors expressed in COS7 cells. Pep 234 (a mammalian KISS1 antagonist) antagonizes Kiss1r signaling activated by Kiss1 and Kiss2, and pep 359 (a novel analog) antagonizes Kiss2 activation of both receptors. In vitro studies using brain slices demonstrated that only Kiss2 can upregulate the expression of the hypophysiotropic gnrh1, which was subsequently diminished by pep 234 and pep 359. In primary pituitary cell cultures, the two antagonists revealed a complex network of putative endogenous and exogenous regulation by kisspeptin. While both kisspeptins stimulate Fsh expression and secretion, Kiss2 predominately induces Lh secretion. Pep 234 and 359 treatment of spawning males hindered sperm production. This effect was accompanied with decreased brain gnrh1 and gnrh2 mRNA levels and peptide content in the pituitary, and increased levels of pituitary Lh, probably due to attenuation of Lh release. Strikingly, the mRNA levels of arginine-vasotocin, the neurons of which in the preoptic area coexpress kiss2r, were dramatically reduced by the antagonists. Our results demonstrate differential actions of Kiss1 and Kiss2 systems along the hypothalamic-pituitary axis and interactions with other neuropeptides, and further reinforce the importance of kisspeptin in the execution of spawning. © 2015 by the Society for the Study of Reproduction, Inc.

The unexpected, long-lasting, UV rebrightening of the superluminous supernova ASASSN-15lh

NASA Astrophysics Data System (ADS)

Godoy-Rivera, D.; Stanek, K. Z.; Kochanek, C. S.; Chen, Ping; Dong, Subo; Prieto, J. L.; Shappee, B. J.; Jha, S. W.; Foley, R. J.; Pan, Y.-C.; Holoien, T. W.-S.; Thompson, Todd. A.; Grupe, D.; Beacom, J. F.

2017-04-01

Given its peak luminosity and early-time spectra, ASASSN-15lh was classified as the most luminous supernova ever discovered. Here, we report a UV rebrightening of ASASSN-15lh observed with Swift during our follow-up campaign. The rebrightening began at t ≃ 90 d (observer frame) after the primary peak and was followed by a ˜120-d long plateau in the bolometric luminosity, before starting to fade again at t ≃ 210 d. ASASSN-15lh rebrightened in the Swift UV bands by ΔmUVW2 ≃ -1.75 mag, ΔmUVM2 ≃ -1.25 mag and ΔmUVW1 ≃ -0.8 mag, but did not rebrighten in the optical bands. Throughout its initial decline, subsequent rebrightening and renewed decline, the spectra did not show evidence of interactions between the ejecta and circumstellar medium such as narrow emission lines. There are hints of weak Hα emission at late-times, but Margutti et al. have shown that it is narrow line emission consistent with star formation in the host nucleus. By fitting a blackbody, we find that during the rebrightening, the effective photospheric temperature increased from TBB ≃ 11 000 K to TBB ≃ 18 000 K. Over the ˜ 550 d since its detection, ASASSN-15lh has radiated ˜1.7 -1.9 × 1052 erg. Although its physical nature remains uncertain, the evolution of ASASSN-15lh's photospheric radius, its radiated energy and the implied event rate, are all more similar to those of H-poor superluminous supernovae than to tidal disruption events.

Selective binding of carotenoids with a shorter conjugated chain to the LH2 antenna complex and those with a longer conjugated chain to the reaction center from Rubrivivax gelatinosus.

PubMed

Kakitani, Yoshinori; Fujii, Ritsuko; Hayakawa, Yoshihiro; Kurahashi, Masahiro; Koyama, Yasushi; Harada, Jiro; Shimada, Keizo

2007-06-19

Rubrivivax gelatinosus having both the spheroidene and spirilloxanthin biosynthetic pathways produces carotenoids (Cars) with a variety of conjugated chains, which consist of different numbers of conjugated double bonds (n), including the C=C (m) and C=O (o) bonds. When grown under anaerobic conditions, the wild type produces Cars for which n = m = 9-13, whereas under semiaerobic conditions, it additionally produces Cars for which n = m + o = 10 + 1, 13 + 1, and 13 + 2. On the other hand, a mutant, in which the latter pathway is genetically blocked, produces only Cars for which n = 9 and 10 under anaerobic conditions and n = 9, 10, and 10 + 1 under semianaerobic conditions. Those Cars that were extracted from the LH2 complex (LH2) and the reaction center (RC), isolated from the wild-type and the mutant Rvi. gelatinosus, were analyzed by HPLC, and their structures were determined by mass spectrometry and 1H NMR spectroscopy. The selective binding of Cars to those pigment-protein complexes has been characterized as follows. (1) Cars with a shorter conjugated chain are selectively bound to LH2 whereas Cars with a longer conjugated chain to the RC. (2) Shorter chain Cars with a hydroxyl group are bound to LH2 almost exclusively. This rule holds either in the absence or in the presence of the keto group. The natural selection of shorter chain Cars by LH2 and longer chain Cars by the RC is discussed, on the basis of the results now available, in relation to the light-harvesting and photoprotective functions of Cars.

Effects of human chorionic gonadotropin combined with clomiphene on Serum E2, FSH, LH and PRL levels in patients with polycystic ovarian syndrome.

PubMed

Yonggang, Huang; Xiaosheng, Lu; Zhaoxia, Huang; Yilu, Chen; Jiqiang, Lv; Huina, Zhang

2017-02-01

Effects of human chorionic gonadotropin combined with clomiphene on serum E 2 , FSH, LH and PRL levels in patients with polycystic ovarian syndrome were analyzed. 90 patients with polycystic ovarian syndrome treated from January 2015 to March 2016 were randomly and evenly divided into control group and observation group. Patients in the control group were only treated with clomiphene. On the basis of the treatment in control group, human chorionic gonadotropin was added in the treatment of observation group. The changes of E 2 , FSH, LH, PRL levels were compared between two groups before and after the treatment. Clinical curative effects of patients in the two groups was evaluated. Adverse reactions during treatment in two groups were observed and recorded. The incidence of adverse reactions was calculated. Serum E 2 , FSH, LH and PRL levels in the two groups decreased significantly after treatment compared with that before treatment. The difference is statistical significant ( P  < 0.05). After the treatment, E 2 , FSH, LH and PRL levels in the observation group were lower than that in the control group and the difference is statistical significant ( P  < 0.05). Total effective rate was 64.44% in the control group and 93.33% in the observation group. There were statistically significant difference in clinical curative effects in the two groups ( P  < 0.05). Different degrees of adverse reactions were found in both groups during treatment, such as nausea, vomiting, anorexia, liver dysfunction. There were 2 cases of nausea, 2 cases of vomiting, 3 cases of anorexia and 1 case of liver dysfunction from the 45 patients in control group. The total incidence of adverse reactions was 17.78% (8/45). There were 1 case of nausea, 1 case of vomiting, 1 case of anorexia and no liver dysfunction from the 45 patients in observation group. The total incidence of adverse reactions was 6.67% (3/45). The total incidence of adverse reactions in the observation group was

Effect of monosaccharide sugars on LH-induced differentiation and sugar transport facilitator (SLC2A) expression in sheep theca cells in vitro.

PubMed

Campbell, B K; Kendall, N R; Onions, V; Guo, L; Scaramuzzi, R J

2014-03-01

The aim of the present study was to investigate the effects of glucose, galactose and fructose on the LH-induced differentiation and mRNA expression of sugar transport facilitators (SLC2A) by sheep thecal cells derived from small antral follicles cultured under serum-free conditions for 6 days. The dose and type of monosaccharide had a significant effect on LH-induced androstenedione production by theca cells and there was a significant interaction (P<0.001). Glucose and galactose were used with equal efficiency so that cell numbers and androstenedione production at the end of the culture were comparable. Pharmacological doses of glucose (16.7 mM) inhibited steroidogenesis (P<0.05). Cell numbers and androstenedione production by cells cultured with fructose were lower than for cells cultured with either glucose or galactose (P<0.001). None of the monosaccharides resulted in the production of lactate. Expression of SLC2A1, SLC2A4 and SLC2A8, but not SLC2A5, mRNA was detected in fresh and cultured theca cells. Large doses (16.7 mM) of glucose and fructose, but not galactose, suppressed (P<0.05) SLC2A expression. The results show that glucose and galactose, but not fructose, are readily metabolised via oxidative pathways to support LH-induced differentiation of sheep theca cells. Further work is required to determine the mechanisms resulting in these differences in relation to the established effects of nutrition on reproductive function.

Bacterial α2-macroglobulins: colonization factors acquired by horizontal gene transfer from the metazoan genome?

PubMed Central

Budd, Aidan; Blandin, Stephanie; Levashina, Elena A; Gibson, Toby J

2004-01-01

Background Invasive bacteria are known to have captured and adapted eukaryotic host genes. They also readily acquire colonizing genes from other bacteria by horizontal gene transfer. Closely related species such as Helicobacter pylori and Helicobacter hepaticus, which exploit different host tissues, share almost none of their colonization genes. The protease inhibitor α2-macroglobulin provides a major metazoan defense against invasive bacteria, trapping attacking proteases required by parasites for successful invasion. Results Database searches with metazoan α2-macroglobulin sequences revealed homologous sequences in bacterial proteomes. The bacterial α2-macroglobulin phylogenetic distribution is patchy and violates the vertical descent model. Bacterial α2-macroglobulin genes are found in diverse clades, including purple bacteria (proteobacteria), fusobacteria, spirochetes, bacteroidetes, deinococcids, cyanobacteria, planctomycetes and thermotogae. Most bacterial species with bacterial α2-macroglobulin genes exploit higher eukaryotes (multicellular plants and animals) as hosts. Both pathogenically invasive and saprophytically colonizing species possess bacterial α2-macroglobulins, indicating that bacterial α2-macroglobulin is a colonization rather than a virulence factor. Conclusions Metazoan α2-macroglobulins inhibit proteases of pathogens. The bacterial homologs may function in reverse to block host antimicrobial defenses. α2-macroglobulin was probably acquired one or more times from metazoan hosts and has then spread widely through other colonizing bacterial species by more than 10 independent horizontal gene transfers. yfhM-like bacterial α2-macroglobulin genes are often found tightly linked with pbpC, encoding an atypical peptidoglycan transglycosylase, PBP1C, that does not function in vegetative peptidoglycan synthesis. We suggest that YfhM and PBP1C are coupled together as a periplasmic defense and repair system. Bacterial α2-macroglobulins might

Luteinizing hormone (LH) levels in male workers exposed to urban stressors.

PubMed

Tomao, Enrico; Tomei, Gianfranco; Rosati, Maria Valeria; Caciari, Tiziana; Danese, Daniele; Gamberale, Daniele; Vacca, Daniele; Palermo, Paola; Anzelmo, Vincenza; Tomei, Francesco

2009-08-01

The aim of the study is to evaluate if occupational exposure to urban stressors could cause alterations in luteinizing hormone (LH) plasma levels in male traffic policemen vs. administrative staff of Municipal Police.After excluding the subjects with the main confounding factors, male traffic police and administrative staff of Municipal Police were matched by age, working life, body mass index (BMI), alcohol drinking habit, cigarette smoking habit and habitual consumption of Italian coffee.In 166 male traffic police mean LH values were significantly higher compared to 166 male administrative employees. The distribution of LH values in traffic police and in administrative employees was statistically significant.Our results suggest that recent exposure to urban stressors (chemical, physical and psycho-social) can alter the plasma concentration of LH. In agreement with our previous research, levels of plasma LH may be used as early biological markers, valuable for the group, used in occupational set before the appearance of the disease.

Investigation of lightweight designs and materials for LO2 and LH2 propellant tanks for space vehicles, phase 1

NASA Technical Reports Server (NTRS)

1975-01-01

Design, analysis, and fabrication studies were performed on nonintegral (suspended) tanks using a representative space tug design. The LH2 and LO2 tank concept selection was developed. Tank geometries and support relationships were investigated using tug design propellant inertias and ullage pressures, then compared based on total tug systems effects. The tank combinations which resulted in the maximum payload were selected. Tests were conducted on samples of membrane material which was processed in a manner simulating production tank fabrication operations to determine fabrication effects on the fracture toughness of the tank material. Fracture mechanics analyses were also performed to establish a preliminary set of allowables for initial defects.

Purified monomeric ligand.MD-2 complexes reveal molecular and structural requirements for activation and antagonism of TLR4 by Gram-negative bacterial endotoxins.

PubMed

Gioannini, Theresa L; Teghanemt, Athmane; Zhang, DeSheng; Esparza, Gregory; Yu, Liping; Weiss, Jerrold

2014-08-01

A major focus of work in our laboratory concerns the molecular mechanisms and structural bases of Gram-negative bacterial endotoxin recognition by host (e.g., human) endotoxin-recognition proteins that mediate and/or regulate activation of Toll-like receptor (TLR) 4. Here, we review studies of wild-type and variant monomeric endotoxin.MD-2 complexes first produced and characterized in our laboratories. These purified complexes have provided unique experimental reagents, revealing both quantitative and qualitative determinants of TLR4 activation and antagonism. This review is dedicated to the memory of Dr. Theresa L. Gioannini (1949-2014) who played a central role in many of the studies and discoveries that are reviewed.

Regional and temporal differences in gene expression of LH(BETA)T(AG) retinoblastoma tumors.

PubMed

Houston, Samuel K; Pina, Yolanda; Clarke, Jennifer; Koru-Sengul, Tulay; Scott, William K; Nathanson, Lubov; Schefler, Amy C; Murray, Timothy G

2011-07-23

The purpose of this study was to evaluate by microarray the hypothesis that LH(BETA)T(AG) retinoblastoma tumors exhibit regional and temporal variations in gene expression. LH(BETA)T(AG) mice aged 12, 16, and 20 weeks were euthanatized (n = 9). Specimens were taken from five tumor areas (apex, anterior lateral, center, base, and posterior lateral). Samples were hybridized to gene microarrays. The data were preprocessed and analyzed, and genes with a P < 0.01, according to the ANOVA models, and a log(2)-fold change >2.5 were considered to be differentially expressed. Differentially expressed genes were analyzed for overlap with known networks by using pathway analysis tools. There were significant temporal (P < 10(-8)) and regional differences in gene expression for LH(BETA)T(AG) retinoblastoma tumors. At P < 0.01 and log(2)-fold change >2.5, there were significant changes in gene expression of 190 genes apically, 84 genes anterolaterally, 126 genes posteriorly, 56 genes centrally, and 134 genes at the base. Differentially expressed genes overlapped with known networks, with significant involvement in regulation of cellular proliferation and growth, response to oxygen levels and hypoxia, regulation of cellular processes, cellular signaling cascades, and angiogenesis. There are significant temporal and regional variations in the LH(BETA)T(AG) retinoblastoma model. Differentially expressed genes overlap with key pathways that may play pivotal roles in murine retinoblastoma development. These findings suggest the mechanisms involved in tumor growth and progression in murine retinoblastoma tumors and identify pathways for analysis at a functional level, to determine significance in human retinoblastoma. Microarray analysis of LH(BETA)T(AG) retinal tumors showed significant regional and temporal variations in gene expression, including dysregulation of genes involved in hypoxic responses and angiogenesis.

Receptor-targeted therapy of human experimental urinary bladder cancers with cytotoxic LH-RH analog AN-152 [AEZS- 108].

PubMed

Szepeshazi, Karoly; Schally, Andrew V; Keller, Gunhild; Block, Norman L; Benten, Daniel; Halmos, Gabor; Szalontay, Luca; Vidaurre, Irving; Jaszberenyi, Miklos; Rick, Ferenc G

2012-07-01

Many bladder cancers progress to invasion with poor prognosis; new therapeutic methods are needed. We developed a cytotoxic LH-RH analog, AN-152 (AEZS-108) containing doxorubicin (DOX), for targeted therapy of cancers expressing LHRH receptors. We investigated the expression of LH-RH receptors in clinical bladder cancers and in HT-1376, J82, RT-4 and HT-1197 human bladder cancer lines. The effect of analog, AN-152, on growth of these tumor lines xenografted into nude mice was analyzed. Using molecular and functional assays, we also evaluated the differences between the effects of AN-152, and DOX alone. We demonstrated the expression of LH-RH receptors on 18 clinical bladder cancers by immunohistochemistry and on four human urinary bladder cancer lines HT-1376, J82, RT-4 and HT-1197 by Western blotting and binding assays. AN-152 powerfully inhibited growth of these bladder cancers in nude mice. AN-152 exerted greater effects than DOX and was less toxic. DOX activated strong multidrug resistance mechanisms in RT-4 and HT-1197 cancers, while AN-152 had no or less such effect. PCR assays and in vitro studies revealed differences in the action of AN-152 and DOX on the expression of genes involved in apoptosis. These results suggest that targeted cytotoxic LH-RH analog, AN-152 (AEZS- 108), should be examined for treatment of patients with LH-RH receptor positive invasive bladder cancers.

Correlation between LH secretion in castrated rats with cellular proliferation and synthesis of DNA in the anterior pituitary gland.

PubMed

Romano, M I; Machiavelli, G A; Pérez, R L; Carricarte, V; Burdman, J A

1984-07-01

The relationship between the release of LH and the synthesis of DNA was studied in the anterior pituitary gland of castrated rats. Cell types were characterized immunocytochemically. Castration significantly (P less than 0.01) increased the concentration of LH in serum (1326%) and the incorporation of [3H]thymidine into pituitary DNA (72%). This was accompanied by an increment in the activity of the enzyme DNA polymerase-alpha (58%) and in the number of mitoses (from 2 +/- 0.1/mm2 in intact rats to 21 +/- 0.8/mm2 15 days after castration). Only 20% of the mitoses found in the pituitary gland of castrated rats were positively stained with the antiserum against the beta-subunit of LH. The other 80% did not stain either with LH antiserum or with antisera against the other pituitary hormones. There was a significant (P less than 0.01) increase in the number of LH cells in castrated rats (48%). All the changes produced in the anterior pituitary gland after castration were prevented by the administration of dihydrotestosterone. The results demonstrate that a stimulation of LH release is followed by an increase of DNA synthesis and cell proliferation of gonadotrophs in the anterior pituitary gland.

Interactome of E. piscicida and grouper liver proteins reveals strategies of bacterial infection and host immune response.

PubMed

Li, Hui; Zhu, Qing-Feng; Peng, Xuan-Xian; Peng, Bo

2017-01-03

The occurrence of infectious diseases is related to heterogeneous protein interactions between a host and a microbe. Therefore, elucidating the host-pathogen interplay is essential. We previously revealed the protein interactome between Edwardsiella piscicida and fish gill cells, and the present study identified the protein interactome between E. piscicida and E. drummondhayi liver cells. E. drummondhayi liver cells and bacterial pull-down approaches were used to identify E. piscicida outer membrane proteins that bind to liver cells and fish liver cell proteins that interact with bacterial cells, respectively. Eight bacterial proteins and 11 fish proteins were characterized. Heterogeneous protein-protein interactions between these bacterial cells and fish liver cells were investigated through far-Western blotting and co-immunoprecipitation. A network was constructed based on 42 heterogeneous protein-protein interactions between seven bacterial proteins and 10 fish proteins. A comparison of the new interactome with the previously reported interactome showed that four bacterial proteins overlapped, whereas all of the identified fish proteins were new, suggesting a difference between bacterial tricks for evading host immunity and the host strategy for combating bacterial infection. Furthermore, these bacterial proteins were found to regulate the expression of host innate immune-related proteins. These findings indicate that the interactome contributes to bacterial infection and host immunity.

Revealing structure and assembly cues for Arabidopsis root-inhabiting bacterial microbiota.

PubMed

Bulgarelli, Davide; Rott, Matthias; Schlaeppi, Klaus; Ver Loren van Themaat, Emiel; Ahmadinejad, Nahal; Assenza, Federica; Rauf, Philipp; Huettel, Bruno; Reinhardt, Richard; Schmelzer, Elmon; Peplies, Joerg; Gloeckner, Frank Oliver; Amann, Rudolf; Eickhorst, Thilo; Schulze-Lefert, Paul

2012-08-02

The plant root defines the interface between a multicellular eukaryote and soil, one of the richest microbial ecosystems on Earth. Notably, soil bacteria are able to multiply inside roots as benign endophytes and modulate plant growth and development, with implications ranging from enhanced crop productivity to phytoremediation. Endophytic colonization represents an apparent paradox of plant innate immunity because plant cells can detect an array of microbe-associated molecular patterns (also known as MAMPs) to initiate immune responses to terminate microbial multiplication. Several studies attempted to describe the structure of bacterial root endophytes; however, different sampling protocols and low-resolution profiling methods make it difficult to infer general principles. Here we describe methodology to characterize and compare soil- and root-inhabiting bacterial communities, which reveals not only a function for metabolically active plant cells but also for inert cell-wall features in the selection of soil bacteria for host colonization. We show that the roots of Arabidopsis thaliana, grown in different natural soils under controlled environmental conditions, are preferentially colonized by Proteobacteria, Bacteroidetes and Actinobacteria, and each bacterial phylum is represented by a dominating class or family. Soil type defines the composition of root-inhabiting bacterial communities and host genotype determines their ribotype profiles to a limited extent. The identification of soil-type-specific members within the root-inhabiting assemblies supports our conclusion that these represent soil-derived root endophytes. Surprisingly, plant cell-wall features of other tested plant species seem to provide a sufficient cue for the assembly of approximately 40% of the Arabidopsis bacterial root-inhabiting microbiota, with a bias for Betaproteobacteria. Thus, this root sub-community may not be Arabidopsis-specific but saprophytic bacteria that would naturally be found

The stellar content of LH 9 and 10 (N11) in the LMC - A case for sequential star formation

NASA Technical Reports Server (NTRS)

Parker, Joel WM.; Garmany, Catharine D.; Massey, Philip; Walborn, Nolan R.

1992-01-01

The young OB associations Lucke-Hodge 9 and 10 are studied with UBV photometry that is independent of reddening to determine the IMF directly from star counts. The temperature and reddening of the stars are determined which, in conjunction with the spectroscopic classification of the earliest stars, is employed to place the stellar groups on the theoretical H-R diagram. Observations are also presented of the highly compact H II region/knot N11A and the multiple system HD 32228, and LH 9 and 10 are compared. The Lyman ionizing flux calculated at 4.9-7.2 x 10 exp 50/s agrees well with flux required to generate the H-alpha luminosity of the H II region. LH 10 has a much flatter slope, a higher ratio of higher-mass to lower-mass stars, and greater reddening than LH 9, and LH 10 contains all of the O stars earlier than O6. It is concluded that LH 9 is older than LH 10 and probably contributed to the initiation of star formation in LH 10.

A quantum mechanical analysis of the light-harvesting complex 2 (LH2) from purple photosynthetic bacteria: insights into the electrostatic effects of transmembrane helices.

PubMed

Pichierri, Fabio

2011-02-01

We perform a quantum mechanical study of the peptides that are part of the LH2 complex from Rhodopseudomonas acidophila, a non-sulfur purple bacteria that has the ability of producing chemical energy from photosynthesis. The electronic structure calculations indicate that the transmembrane helices of these peptides are characterized by dipole moments with a magnitude of about 150D. When the full nonamer assembly made of 18 peptides is considered, then a macrodipole of magnitude 806D is built up from the vector sum of each monomer dipole. The macrodipole is oriented normal to the membrane plane and with the positive tip toward the cytoplasm thereby indicating that the electronic charge of the protein scaffold is polarized toward the periplasm. The results obtained here suggest that the asymmetric charge distribution of the protein scaffold contributes an anisotropic electrostatic environment which differentiates the absorption properties of the bacteriochlorophyll pigments, B800 and B850, embedded in the LH2 complex. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

LH pulses and the corpus luteum: the luteal phase deficiency LPD).

PubMed

Wuttke, W; Pitzel, L; Seidlová-Wuttke, D; Hinney, B

2001-01-01

The proper function of the GnRH pulse generator in the hypothalamus is essential for normal ovarian function, hence also for proper function of the corpus luteum. During the luteal phase LH pulses stimulate progesterone release, which is essential for normal endometrial transformation. Approximately one-half of all luteal phase deficiencies (LPD) are due to improper function of the GnRH pulse generator. Obviously, following ovulation the increased serum progesterone levels oversuppress the GnRH pulse generator, resulting in too few LH pulses and therefore improper luteal function. Also, latent hyperprolactinemia may lead to an LPD which can be effectively treated with plant extracts containing dopaminergic (prolactin-suppressing) compounds. Our increasing knowledge of auto- and paracrine mechanisms between nonsteroidogenic and steroidogenic cells now allow subclassification of LPDs of ovarian origin. The so-called small luteal cells are LH-responsive. If they develop improperly the regularly occurring LH pulses are unable to stimulate progesterone secretion from the small luteal cells, which results in what we call the small luteal cell defect. In addition, there is also evidence that the large luteal cells may function improperly. Hence, basal progesterone release is too low while LH-stimulated progesterone release from the small luteal cells appears to be intact. This subclassification of luteal phase deficiency results in the suggestion of different treatments. In cases where the corpus luteum is LH-responsive, such as the hypothalamic corpus luteum insufficiency and the large luteal cell defect, HCG treatment or pulsatile treatment with GnRH is advisable. In the case of LH/hCG-unresponsive small luteal cell defect a progesterone substitution is suggested.

Evaluation of different ranges of LH:FSH ratios in polycystic ovarian syndrome (PCOS) - Clinical based case control study.

PubMed

Malini, N A; Roy George, K

2018-05-01

Polycystic ovary syndrome (PCOS) is a highly prevalent endocrine and metabolic disorder among reproductive aged women, leading to infertility. One of the common clinical manifestations in PCOS is that there is a difference in the range of LH production in different case of PCOS and accordingly variability in LH:FSH ratio was observed. The aim of the present study was to evaluate different ranges of LH:FSH ratios in PCOS. In this cross sectional study, a consecutive series of 745 women (aged 28.11 ± 0.2) who were subjected to infertility treatment at specialist infertility clinics in central Travancore region were considered. About 50 healthy females (aged 27.58 ± 0.4) with regular menstrual cycles were regarded as control. The data were collected from hospital records using subject's written informed consent. PCOS patients were observed to have different ranges of LH:FSH ratios from < 1 range to 4.6-5.5 and subjects were classified into 7 PCO subgroups on the basis of their LH:FSH ratios. In whole PCO group, body weight, LH, FSH, LH:FSH ratio, insulin, HbA1c, estradiol, testosterone and TSH were significantly (P < .05) increased whereas progesterone and SHBG levels were significantly (P < .05) decreased in comparison to control. In various PCO subgroups as LH levels and LH:FSH ratios were increased, levels of insulin, testosterone and AMH were increased and SHBG levels were decreased accordingly. This finding suggested a dependence of insulin, LH and testosterone in initiating the hormonal imbalances in PCOS. Copyright © 2018 Elsevier Inc. All rights reserved.

Long-term subcutaneous pulsatile low dose LH-RH administration for treatment of infertile men with secondary hypogonadotrophic hypogonadism.

PubMed

Skarin, G; Nillius, S J; Wide, L

1984-01-01

Chronic pulsatile subcutaneous low dose LH-RH treatment was given to three infertile men with longstanding (2-4 years) secondary hypothalamic pituitary failure. Before the therapy they had very low serum concentrations of gonadotrophins and testosterone. They were impotent and could not produce any ejaculate for sperm analysis. The pulsatile LH-RH treatment, which was continued up to 250 days, was given by means of a small portable automatically-timed infusion pump. Fifty microliter of the LH-RH solution was infused during one min every 90 min. The LH-RH doses were 1, 5 and 20 micrograms. The serum concentrations of the gonadotrophins and testosterone were normalized in the three patients within 10 days of pulsatile low dose LH-RH therapy. Libido and potency returned. The first ejaculates contained no sperms. With continued LH-RH treatment spermatogenesis was induced and normalized. Two of the men fertilized their wives. The pregnancy tests were positive after 181 and 230 days of treatment, respectively. Two healthy girls have been born. Paternity tests were positive. The third man is still receiving pulsatile LH-RH therapy. He has up till now been treated for four months. Chronic pulsatile s.c. low dose LH-RH administration is a very promising new therapy for those hypogonadal men who previously have required human gonadotrophin treatment to restore fertility.

Monoclonal antibodies against loggerhead sea turtle, Caretta caretta, IgY isoforms reveal differential contributions to antibody titers and relatedness among other sea turtles.

PubMed

Rodgers, Maria L; Rice, Charles D

2018-05-19

Serum from loggerhead sea turtles, Caretta caretta, was collected from the southeast Atlantic Ocean during routine summer monitoring studies in 2017. Serum immunoglobulin IgY was purified and used to develop IgY isoform-specific monoclonal antibodies (mAb). mAb LH12 was developed against the 66 kDa heavy chain of IgY, mAb LH1 was developed against the truncated heavy chain of approximately 37 kDA, and mAb LH9 was developed against the 23 kDa light chains. mAb LH9 reacts with the light chains of all sea turtles, mAb LH12 reacts with the long heavy chain of all sea turtles within the family Cheloniidae, and mAb LH1 reacts with the truncated form of IgY in both olive and Kemp's ridley turtles. Circulating IgY antibodies against three different marine bacterial pathogens were determined in 16 loggerhead samples using these mAbs. mAb LH12 detects higher titers than mAb LH1, and mAb LH9 detects the highest titers. Copyright © 2018 Elsevier Ltd. All rights reserved.

Unified analysis of ensemble and single-complex optical spectral data from light-harvesting complex-2 chromoproteins for gaining deeper insight into bacterial photosynthesis

NASA Astrophysics Data System (ADS)

Pajusalu, Mihkel; Kunz, Ralf; Rätsep, Margus; Timpmann, Kõu; Köhler, Jürgen; Freiberg, Arvi

2015-11-01

Bacterial light-harvesting pigment-protein complexes are very efficient at converting photons into excitons and transferring them to reaction centers, where the energy is stored in a chemical form. Optical properties of the complexes are known to change significantly in time and also vary from one complex to another; therefore, a detailed understanding of the variations on the level of single complexes and how they accumulate into effects that can be seen on the macroscopic scale is required. While experimental and theoretical methods exist to study the spectral properties of light-harvesting complexes on both individual complex and bulk ensemble levels, they have been developed largely independently of each other. To fill this gap, we simultaneously analyze experimental low-temperature single-complex and bulk ensemble optical spectra of the light-harvesting complex-2 (LH2) chromoproteins from the photosynthetic bacterium Rhodopseudomonas acidophila in order to find a unique theoretical model consistent with both experimental situations. The model, which satisfies most of the observations, combines strong exciton-phonon coupling with significant disorder, characteristic of the proteins. We establish a detailed disorder model that, in addition to containing a C2-symmetrical modulation of the site energies, distinguishes between static intercomplex and slow conformational intracomplex disorders. The model evaluations also verify that, despite best efforts, the single-LH2-complex measurements performed so far may be biased toward complexes with higher Huang-Rhys factors.

Unified analysis of ensemble and single-complex optical spectral data from light-harvesting complex-2 chromoproteins for gaining deeper insight into bacterial photosynthesis.

PubMed

Pajusalu, Mihkel; Kunz, Ralf; Rätsep, Margus; Timpmann, Kõu; Köhler, Jürgen; Freiberg, Arvi

2015-01-01

Bacterial light-harvesting pigment-protein complexes are very efficient at converting photons into excitons and transferring them to reaction centers, where the energy is stored in a chemical form. Optical properties of the complexes are known to change significantly in time and also vary from one complex to another; therefore, a detailed understanding of the variations on the level of single complexes and how they accumulate into effects that can be seen on the macroscopic scale is required. While experimental and theoretical methods exist to study the spectral properties of light-harvesting complexes on both individual complex and bulk ensemble levels, they have been developed largely independently of each other. To fill this gap, we simultaneously analyze experimental low-temperature single-complex and bulk ensemble optical spectra of the light-harvesting complex-2 (LH2) chromoproteins from the photosynthetic bacterium Rhodopseudomonas acidophila in order to find a unique theoretical model consistent with both experimental situations. The model, which satisfies most of the observations, combines strong exciton-phonon coupling with significant disorder, characteristic of the proteins. We establish a detailed disorder model that, in addition to containing a C_{2}-symmetrical modulation of the site energies, distinguishes between static intercomplex and slow conformational intracomplex disorders. The model evaluations also verify that, despite best efforts, the single-LH2-complex measurements performed so far may be biased toward complexes with higher Huang-Rhys factors.

[Low-dose desmopressin (DDAVP) and blood levels of FSH, LH and testosterone in men].

PubMed

García-Pascual, I J; Rozán Flores, M A

1996-03-01

The effect of desmopressin (DDAVP) administration (2.5 micrograms/12 hours) on serum concentrations of FSH, LH and testosterone was studied in six men. No significant changes were observed in serum concentrations of FSH and LH after 9 days with DDAVP therapy. Nevertheless, serum concentrations of testosterone after 12 hours of DDAVP administration were significantly higher than basal concentrations. Three hours after the administration of DDAVP, serum testosterone concentrations decreased significantly. The conclusion reached was that low doses of desmopressin do not change serum concentrations of FSH and LH, but serum concentration of testosterone is decreased within three hours after the administration, although an increase is observed 12 hours later possibly due to a "rebound effect". Desmopressin would therefore directly act upon human testicle.

Deep sequencing reveals exceptional diversity and modes of transmission for bacterial sponge symbionts

PubMed Central

Webster, Nicole S; Taylor, Michael W; Behnam, Faris; Lücker, Sebastian; Rattei, Thomas; Whalan, Stephen; Horn, Matthias; Wagner, Michael

2010-01-01

Marine sponges contain complex bacterial communities of considerable ecological and biotechnological importance, with many of these organisms postulated to be specific to sponge hosts. Testing this hypothesis in light of the recent discovery of the rare microbial biosphere, we investigated three Australian sponges by massively parallel 16S rRNA gene tag pyrosequencing. Here we show bacterial diversity that is unparalleled in an invertebrate host, with more than 250 000 sponge-derived sequence tags being assigned to 23 bacterial phyla and revealing up to 2996 operational taxonomic units (95% sequence similarity) per sponge species. Of the 33 previously described ‘sponge-specific’ clusters that were detected in this study, 48% were found exclusively in adults and larvae – implying vertical transmission of these groups. The remaining taxa, including ‘Poribacteria’, were also found at very low abundance among the 135 000 tags retrieved from surrounding seawater. Thus, members of the rare seawater biosphere may serve as seed organisms for widely occurring symbiont populations in sponges and their host association might have evolved much more recently than previously thought. PMID:21966903

Turbulence and sheared flow structures behind the isotopic dependence of the L-H power threshold on DIII-D

NASA Astrophysics Data System (ADS)

Yan, Z.; Gohil, P.; McKee, G. R.; Eldon, D.; Grierson, B.; Rhodes, T.; Petty, C. C.

2017-12-01

Measurements of long wavelength ({{k}\\bot }{{ρ }i}   <  1) density fluctuation characteristics in the edge of both Deuterium (D) and Hydrogen (H) plasmas across the L-H transition on DIII-D demonstrate the existence of single or double bands of low-wavenumber turbulence observed near the edge of H and D plasmas. These are strongly correlated with the L to H-mode transition power threshold (P LH) and can help explain the isotopic and density dependence of P LH, and how the P LH difference is reduced at higher density. Understanding and accurately predicting the L-H power threshold is critical to accessing to H-mode, and operating and achieving high confinement in burning plasmas such as ITER. Above about n e ~ 4  ×  1019 m-3, P LH is seen to converge for H and D, and increases for both with higher density. Surprisingly, the P LH increases significantly at low density in H but not in D plasmas. Two distinct frequency bands of density fluctuations are observed in the D plasmas at low density, n e ~ 1.2-1.5  ×  1019 m-3, but not in H plasmas with similar density, which appears to be correlated to the much lower power threshold in D at low density. Consistently, E  ×  B shear in the region of r/a ~ 0.95-1.0 is larger in D plasmas than in H plasmas at low density; as the P LH increases with increasing density, the dual mode structure disappears while E  ×  B shear becomes similar and small for both D and H plasmas at higher density, n e ~ 5  ×  1019 m-3, where P LH is similar for both D and H plasmas. The increased edge fluctuations, increased flow shear, and the dual-band nature of edge turbulence correlating with lower P LH may account for the strong isotope and density dependencies of P LH and support current L-H transition theories but suggest a complex behavior that can inform a more complete model of the L-H transition threshold.

Effects of Calcium Ions on the Thermostability and Spectroscopic Properties of the LH1-RC Complex from a New Thermophilic Purple Bacterium Allochromatium tepidum.

PubMed

Kimura, Yukihiro; Lyu, Shuwen; Okoshi, Akira; Okazaki, Koudai; Nakamura, Natsuki; Ohashi, Akira; Ohno, Takashi; Kobayashi, Manami; Imanishi, Michie; Takaichi, Shinichi; Madigan, Michael T; Wang-Otomo, Zheng-Yu

2017-05-18

The light harvesting-reaction center (LH1-RC) complex from a new thermophilic purple sulfur bacterium Allochromatium (Alc.) tepidum was isolated and characterized by spectroscopic and thermodynamic analyses. The purified Alc. tepidum LH1-RC complex showed a high thermostability comparable to that of another thermophilic purple sulfur bacterium Thermochromatium tepidum, and spectroscopic characteristics similar to those of a mesophilic bacterium Alc. vinosum. Approximately 4-5 Ca 2+ per LH1-RC were detected by inductively coupled plasma atomic emission spectroscopy and isothermal titration calorimetry. Upon removal of Ca 2+ , the denaturing temperature of the Alc. tepidum LH1-RC complex dropped accompanied by a blue-shift of the LH1 Q y absorption band. The effect of Ca 2+ was also observed in the resonance Raman shift of the C3-acetyl νC═O band of bacteriochlorophyll-a, indicating changes in the hydrogen-bonding interactions between the pigment and LH1 polypeptides. Thermodynamic parameters for the Ca 2+ -binding to the Alc. tepidum LH1-RC complex indicated that this reaction is predominantly driven by the largely favorable electrostatic interactions that counteract the unfavorable negative entropy change. Our data support a hypothesis that Alc. tepidum may be a transitional organism between mesophilic and thermophilic purple bacteria and that Ca 2+ is one of the major keys to the thermostability of LH1-RC complexes in purple bacteria.

Assessment of crash fire hazard of LH sub 2 fueled aircraft

NASA Technical Reports Server (NTRS)

Brewer, G. D.; Wittlin, G.; Versaw, E. F.; Parmley, R.; Cima, R.; Walther, E. G.

1981-01-01

The relative safety of passengers in LH2 - fueled aircraft, as well as the safety of people in areas surrounding a crash scene, has been evaluated in an analytical study. Four representative circumstances were postulated involving a transport aircraft in which varying degrees of severity of damage were sustained. Potential hazard to the passengers and to the surroundings posed by the spilled fuel was evaluated for each circumstance. Corresponding aircraft fueled with liquid methane, Jet A, and JP-4 were also studied in order to make comparisons of the relative safety. The four scenarios which were used to provide a basis for the evaluation included: (1) a small fuel leak internal to the aircraft, (2) a survivable crash in which a significant quantity of fuel is spilled in a radial pattern as a result of impact with a stationary object while taxiing at fairly low speed, (3) a survivable crash in which a significant quantity of fuel is spilled in an axial pattern as a result of impact during landing, and (4) a non-survivable crash in which a massive fuel spill occurs instantaneously.

Structure of the dimeric RC–LH1–PufX complex from Rhodobaca bogoriensis investigated by electron microscopy

PubMed Central

Semchonok, Dmitry A.; Chauvin, Jean-Paul; Frese, Raoul N.; Jungas, Colette; Boekema, Egbert J.

2012-01-01

Electron microscopy and single-particle averaging were performed on isolated reaction centre (RC)—antenna complexes (RC–LH1–PufX complexes) of Rhodobaca bogoriensis strain LBB1, with the aim of establishing the LH1 antenna conformation, and, in particular, the structural role of the PufX protein. Projection maps of dimeric complexes were obtained at 13 Å resolution and show the positions of the 2 × 14 LH1 α- and β-subunits. This new dimeric complex displays two open, C-shaped LH1 aggregates of 13 αβ polypeptides partially surrounding the RCs plus two LH1 units forming the dimer interface in the centre. Between the interface and the two half rings are two openings on each side. Next to the openings, there are four additional densities present per dimer, considered to be occupied by four copies of PufX. The position of the RC in our model was verified by comparison with RC–LH1–PufX complexes in membranes. Our model differs from previously proposed configurations for Rhodobacter species in which the LH1 ribbon is continuous in the shape of an S, and the stoichiometry is of one PufX per RC. PMID:23148268

Microbiome analysis reveals the abundance of bacterial pathogens in Rousettus leschenaultii guano

PubMed Central

Banskar, Sunil; Bhute, Shrikant S.; Suryavanshi, Mangesh V.; Punekar, Sachin; Shouche, Yogesh S.

2016-01-01

Bats are crucial for proper functioning of an ecosystem. They provide various important services to ecosystem and environment. While, bats are well-known carrier of pathogenic viruses, their possible role as a potential carrier of pathogenic bacteria is under-explored. Here, using culture-based approach, employing multiple bacteriological media, over thousand bacteria were cultivated and identified from Rousettus leschenaultii (a frugivorous bat species), the majority of which were from the family Enterobacteriaceae and putative pathogens. Next, pathogenic potential of most frequently cultivated component of microbiome i.e. Escherichia coli was assessed to identify its known pathotypes which revealed the presence of virulent factors in many cultivated E. coli isolates. Applying in-depth bacterial community analysis using high-throughput 16 S rRNA gene sequencing, a high inter-individual variation was observed among the studied guano samples. Interestingly, a higher diversity of bacterial communities was observed in decaying guano representative. The search against human pathogenic bacteria database at 97% identity, a small proportion of sequences were found associated to well-known human pathogens. The present study thus indicates that this bat species may carry potential bacterial pathogens and advice to study the effect of these pathogens on bats itself and the probable mode of transmission to humans and other animals. PMID:27845426

Microbiome analysis reveals the abundance of bacterial pathogens in Rousettus leschenaultii guano.

PubMed

Banskar, Sunil; Bhute, Shrikant S; Suryavanshi, Mangesh V; Punekar, Sachin; Shouche, Yogesh S

2016-11-15

Bats are crucial for proper functioning of an ecosystem. They provide various important services to ecosystem and environment. While, bats are well-known carrier of pathogenic viruses, their possible role as a potential carrier of pathogenic bacteria is under-explored. Here, using culture-based approach, employing multiple bacteriological media, over thousand bacteria were cultivated and identified from Rousettus leschenaultii (a frugivorous bat species), the majority of which were from the family Enterobacteriaceae and putative pathogens. Next, pathogenic potential of most frequently cultivated component of microbiome i.e. Escherichia coli was assessed to identify its known pathotypes which revealed the presence of virulent factors in many cultivated E. coli isolates. Applying in-depth bacterial community analysis using high-throughput 16 S rRNA gene sequencing, a high inter-individual variation was observed among the studied guano samples. Interestingly, a higher diversity of bacterial communities was observed in decaying guano representative. The search against human pathogenic bacteria database at 97% identity, a small proportion of sequences were found associated to well-known human pathogens. The present study thus indicates that this bat species may carry potential bacterial pathogens and advice to study the effect of these pathogens on bats itself and the probable mode of transmission to humans and other animals.

A comparison between r-LH and urinary supplements containing LH activity in patients undergoing the microdose GnRH agonist flare protocol for in-vitro fertilization: a pilot study.

PubMed

Shavit, Tal; Agdi, Mohammed; Son, Weon Y; Hasson, Josseph; Dahan, Michael H

2016-08-01

The aim of this study was to compare pregnancy rates and stimulation parameters in patients with diminished ovarian reserve, who were treated with recombinant human luteinizing hormone (r-LH) or menopausal gonadotropins (hMG), as part of a microdose flare protocol. A retrospective cohort study was performed. Comparisons between the group that was stimulated with r-LH plus follicle stimulating hormone (FSH) to those treated with hMG and FSH, were performed. Measurements included: medication doses, number of oocyte collected, number of embryos obtained, pregnancy and clinical pregnancy rates. Patients in the r-LH group (N.=40) had significant higher clinical pregnancy rates (33% vs. 14%; P=0.04) and used lower dose of LH (1938 IU vs. 2807 IU; P=0.02) compared to patients that were stimulated with hMG (N.=39). r-LH may offer advantages for the treatment of diminished ovarian reserve when performing a microdose flare protocol when compared to hMG. Both larger and prospective studies should be carried out to confirm these findings.

[Morinda Officinalis How improves cellphone radiation-induced abnormality of LH and LHR in male rats].

PubMed

Li, Rong; Yang, Wei-qun; Chen, Hui-qin; Zhang, Yong-hong

2015-09-01

To investigate the effects of Morina Officinalis How (MOH) on the abnormal levels of serum luteotrophic hormone (LH) and LH receptor (LHR) in the testis tissue induced by cellphone radiation (CPR) in rats. Fifty adult male SD rats were randomly divided into five groups of equal number: sham CPR, untreated CPR, negative double distilled water (DDW) control, aqueous MOH extract, and alcohol MOH extract. All the animals were exposed to mobile phone radiation except those of the sham CPR group. Then, the rats of the latter two groups were treated intragastrically with MOH at 20 g per kg of the body weight per day in water and alcohol, respectively. After 2. weeks of treatment, all the rats were sacrificed for measurement of the levels of serum LH and LHR in the testis tissue. The levels of serum LH and LHR were 30.15 ± 8.71 and 33.28 ± 6.61 in the aqueous MOH group and 0.96 ± 0.06 and 0.94 ± 0.08 in the alcohol MOH group, both significantly decreased as compared with the negative DDW controls (P < 0.05), but with no remarkable difference between the two MOH groups (P > 0.05). MOH can improve CPR-induced abnormality of LH and LHR in adult male rats.

LH-21 and abnormal cannabidiol improve β-cell function in isolated human and mouse islets through GPR55-dependent and -independent signalling.

PubMed

Ruz-Maldonado, Inmaculada; Pingitore, Attilio; Liu, Bo; Atanes, Patricio; Huang, Guo Cai; Baker, David; Alonso, Francisco José; Bermúdez-Silva, Francisco Javier; Persaud, Shanta J

2018-04-01

To examine the effects of Abn-CBD (GPR55 agonist) and LH-21 (CB1 antagonist) on human and mouse islet function, and to determine signalling via GPR55 using islets from GPR55 -/- mice. Islets isolated from human organ donors and mice were incubated in the absence or presence of Abn-CBD or LH-21, and insulin secretion, [Ca 2+ ] i, cAMP , apoptosis, β-cell proliferation and CREB and AKT phosphorylation were examined using standard techniques. Abn-CBD potentiated glucose-stimulated insulin secretion and elevated [Ca 2+ ] i in human islets and islets from both GPR55 +/+ and GPR55 -/- mice. LH-21 also increased insulin secretion and [Ca 2+ ] i in human islets and GPR55 +/+ mouse islets, but concentrations of LH-21 up to 0.1 μM were ineffective in islets from GPR55 -/- mice. Neither ligand affected basal insulin secretion or islet cAMP levels. Abn-CBD and LH-21 reduced cytokine-induced apoptosis in human islets and GPR55 +/+ mouse islets, and these effects were suppressed after GPR55 deletion. They also increased β-cell proliferation: the effects of Abn-CBD were preserved in islets from GPR55 -/- mice, while those of LH-21 were abolished. Abn-CBD and LH-21 increased AKT phosphorylation in mouse and human islets. This study showed that Abn-CBD and LH-21 improve human and mouse islet β-cell function and viability. Use of islets from GPR55 -/- mice suggests that designation of Abn-CBD and LH-21 as a GPR55 agonist and a CB1 antagonist, should be revised. © 2017 John Wiley & Sons Ltd.

Turbulence and sheared flow structures behind the isotopic dependence of the L-H power threshold on DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Zheng; Gohil, Punit; McKee, George R.

Measurements of long wavelength (kmore » $$\\perp$$p i < 1) density fluctuation characteristics in the edge of both Deuterium (D) and Hydrogen (H) plasmas across the L-H transition on DIII-D demonstrate the existence of single or double bands of low-wavenumber turbulence observed near the edge of H and D plasmas. These are strongly correlated with the L to H-mode transition power threshold (P LH) and can help explain the isotopic and density dependence of P LH, and how the P LH difference is reduced at higher density. Understanding and accurately predicting the L-H power threshold is critical to accessing to H-mode, and operating and achieving high confinement in burning plasmas such as ITER. Above about n e ~ 4 × 10 19 m -3, P LH is seen to converge for H and D, and increases for both with higher density. Surprisingly, the P LH increases significantly at low density in H but not in D plasmas. Two distinct frequency bands of density fluctuations are observed in the D plasmas at low density, n e ~ 1.2-1.5 × 10 19 m -3, but not in H plasmas with similar density, which appears to be correlated to the much lower power threshold in D at low density. Consistently, E × B shear in the region of r/a ~ 0.95-1.0 is larger in D plasmas than in H plasmas at low density; as the P LH increases with increasing density, the dual mode structure disappears while E × B shear becomes similar and small for both D and H plasmas at higher density, n e ~ 5 × 10 19 m -3, where P LH is similar for both D and H plasmas. Lastly, the increased edge fluctuations, increased flow shear, and the dualband nature of edge turbulence correlating with lower P LH may account for the strong isotope and density dependencies of PLH and support current L-H transition theories but suggest a complex behavior that can inform a more complete model of the L-H transition threshold.« less

Turbulence and sheared flow structures behind the isotopic dependence of the L-H power threshold on DIII-D

DOE PAGES

Yan, Zheng; Gohil, Punit; McKee, George R.; ...

2017-09-18

Measurements of long wavelength (kmore » $$\\perp$$p i < 1) density fluctuation characteristics in the edge of both Deuterium (D) and Hydrogen (H) plasmas across the L-H transition on DIII-D demonstrate the existence of single or double bands of low-wavenumber turbulence observed near the edge of H and D plasmas. These are strongly correlated with the L to H-mode transition power threshold (P LH) and can help explain the isotopic and density dependence of P LH, and how the P LH difference is reduced at higher density. Understanding and accurately predicting the L-H power threshold is critical to accessing to H-mode, and operating and achieving high confinement in burning plasmas such as ITER. Above about n e ~ 4 × 10 19 m -3, P LH is seen to converge for H and D, and increases for both with higher density. Surprisingly, the P LH increases significantly at low density in H but not in D plasmas. Two distinct frequency bands of density fluctuations are observed in the D plasmas at low density, n e ~ 1.2-1.5 × 10 19 m -3, but not in H plasmas with similar density, which appears to be correlated to the much lower power threshold in D at low density. Consistently, E × B shear in the region of r/a ~ 0.95-1.0 is larger in D plasmas than in H plasmas at low density; as the P LH increases with increasing density, the dual mode structure disappears while E × B shear becomes similar and small for both D and H plasmas at higher density, n e ~ 5 × 10 19 m -3, where P LH is similar for both D and H plasmas. Lastly, the increased edge fluctuations, increased flow shear, and the dualband nature of edge turbulence correlating with lower P LH may account for the strong isotope and density dependencies of PLH and support current L-H transition theories but suggest a complex behavior that can inform a more complete model of the L-H transition threshold.« less

Tyk2 as a target for immune regulation in human viral/bacterial pneumonia.

PubMed

Berg, Johanna; Zscheppang, Katja; Fatykhova, Diana; Tönnies, Mario; Bauer, Torsten T; Schneider, Paul; Neudecker, Jens; Rückert, Jens C; Eggeling, Stephan; Schimek, Maria; Gruber, Achim D; Suttorp, Norbert; Hippenstiel, Stefan; Hocke, Andreas C

2017-07-01

The severity and lethality of influenza A virus (IAV) infections is frequently aggravated by secondary bacterial pneumonia. However, the mechanisms in human lung tissue that provoke this increase in fatality are unknown and therapeutic immune modulatory options are lacking.We established a human lung ex vivo co-infection model to investigate innate immune related mechanisms contributing to the susceptibility of secondary pneumococcal pneumonia.We revealed that type I and III interferon (IFN) inhibits Streptococcus pneumoniae -induced interleukin (IL)-1β release. The lack of IL-1β resulted in the repression of bacterially induced granulocyte-macrophage colony-stimulating factor (GM-CSF) liberation. Specific inhibition of IFN receptor I and III-associated tyrosine kinase 2 (Tyk2) completely restored the S. pneumoniae -induced IL-1β-GM-CSF axis, leading to a reduction of bacterial growth. A preceding IAV infection of the human alveolus leads to a type I and III IFN-dependent blockade of the early cytokines IL-1β and GM-CSF, which are key for orchestrating an adequate innate immune response against bacteria. Their virally induced suppression may result in impaired bacterial clearance and alveolar repair.Pharmacological inhibition of Tyk2 might be a new treatment option to sustain beneficial endogenous GM-CSF levels in IAV-associated secondary bacterial pneumonia. Copyright ©ERS 2017.

Automatic location of L/H transition times for physical studies with a large statistical basis

NASA Astrophysics Data System (ADS)

González, S.; Vega, J.; Murari, A.; Pereira, A.; Dormido-Canto, S.; Ramírez, J. M.; contributors, JET-EFDA

2012-06-01

Completely automatic techniques to estimate and validate L/H transition times can be essential in L/H transition analyses. The generation of databases with hundreds of transition times and without human intervention is an important step to accomplish (a) L/H transition physics analysis, (b) validation of L/H theoretical models and (c) creation of L/H scaling laws. An entirely unattended methodology is presented in this paper to build large databases of transition times in JET using time series. The proposed technique has been applied to a dataset of 551 JET discharges between campaigns C21 and C26. A prediction with discharges that show a clear signature in time series is made through the locating properties of the wavelet transform. It is an accurate prediction and the uncertainty interval is ±3.2 ms. The discharges with a non-clear pattern in the time series use an L/H mode classifier based on discharges with a clear signature. In this case, the estimation error shows a distribution with mean and standard deviation of 27.9 ms and 37.62 ms, respectively. Two different regression methods have been applied to the measurements acquired at the transition times identified by the automatic system. The obtained scaling laws for the threshold power are not significantly different from those obtained using the data at the transition times determined manually by the experts. The automatic methods allow performing physical studies with a large number of discharges, showing, for example, that there are statistically different types of transitions characterized by different scaling laws.

Adaptation of Rhodopseudomonas acidophila strain 7050 to growth at different light intensities: what are the benefits to changing the type of LH2?

DOE PAGES

Gardiner, A. T.; Niedzwiedzki, D. M.; Cogdell, R. J.

2018-01-01

Femto-second time resolved absorption has been used to investigate how the energy transfer properties in the membranes of high-light and low-light adapted cells change as the composition of the LH2 complexes varies.

Adaptation of Rhodopseudomonas acidophila strain 7050 to growth at different light intensities: what are the benefits to changing the type of LH2?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardiner, A. T.; Niedzwiedzki, D. M.; Cogdell, R. J.

Femto-second time resolved absorption has been used to investigate how the energy transfer properties in the membranes of high-light and low-light adapted cells change as the composition of the LH2 complexes varies.

Energies and excited-state dynamics of 1Bu+, 1Bu- and 3Ag- states of carotenoids bound to LH2 antenna complexes from purple photosynthetic bacteria

NASA Astrophysics Data System (ADS)

Christiana, Rebecca; Miki, Takeshi; Kakitani, Yoshinori; Aoyagi, Shiho; Koyama, Yasushi; Limantara, Leenawaty

2009-10-01

Time-resolved pump-probe stimulated-emission and transient-absorption spectra were recorded after excitation with ˜30 fs pulses to the 1Bu+(0) and optically-forbidden diabatic levels of carotenoids, neurosporene, spheroidene and lycopene having n = 9-11 double bonds, bound to LH2 antenna complexes from Rhodobacter sphaeroides G1C, 2.4.1 and Rhodospirillum molischianum. The low-energy shift of stimulated emission from the covalent 1Bu-(0) and 3Ag-(0) levels slightly larger than that from the ionic 1Bu+(0) state suggests the polarization, whereas more efficient triplet generation suggests the twisting of the conjugated chain in Cars bound to the LH2 complexes, when compared to Cars free in solution.

Nutritional regulation of LH secretion in gilts: Hypothalamic expression of kisspeptin and neurokinin B

USDA-ARS?s Scientific Manuscript database

Puberty, brought about by changes in LH pulse frequency and amplitude, is metabolically gated in the pig. How nutrition regulates LH secretion to initiate puberty in gilts is largely unknown. Kisspeptin (Kiss1) and neurokinin B (NKB) are neuropeptides that have been implicated in regulating LH pulsa...

Deep sequencing reveals exceptional diversity and modes of transmission for bacterial sponge symbionts.

PubMed

Webster, Nicole S; Taylor, Michael W; Behnam, Faris; Lücker, Sebastian; Rattei, Thomas; Whalan, Stephen; Horn, Matthias; Wagner, Michael

2010-08-01

Marine sponges contain complex bacterial communities of considerable ecological and biotechnological importance, with many of these organisms postulated to be specific to sponge hosts. Testing this hypothesis in light of the recent discovery of the rare microbial biosphere, we investigated three Australian sponges by massively parallel 16S rRNA gene tag pyrosequencing. Here we show bacterial diversity that is unparalleled in an invertebrate host, with more than 250,000 sponge-derived sequence tags being assigned to 23 bacterial phyla and revealing up to 2996 operational taxonomic units (95% sequence similarity) per sponge species. Of the 33 previously described 'sponge-specific' clusters that were detected in this study, 48% were found exclusively in adults and larvae - implying vertical transmission of these groups. The remaining taxa, including 'Poribacteria', were also found at very low abundance among the 135,000 tags retrieved from surrounding seawater. Thus, members of the rare seawater biosphere may serve as seed organisms for widely occurring symbiont populations in sponges and their host association might have evolved much more recently than previously thought. © 2009 Society for Applied Microbiology and Blackwell Publishing Ltd.

The equine LH/CGβ subunit combines divergent intracellular traits of the human LHβ and CGβ subunits

PubMed Central

Cohen, Limor; Bousfield, George R; Ben-Menahem, David

2017-01-01

The pituitary LHβ and placental CGβ subunits are products of different genes in primates. The major structural difference between the two subunits is in the carboxy-terminal region, where the short carboxyl sequence of hLHβ is replaced by a longer O-glycosylated carboxy-terminal peptide (CTP) in hCGβ. In association with this structural deviation, there are marked differences in the secretion kinetics and polarized routing of the two subunits. In equids, however, the CGβ and LHβ subunits are products of the same gene expressed in the placenta and pituitary (eLH/CGβ), and both contain a CTP. This unusual expression pattern intrigued us and led to our study of eLH/CGβ subunit secretion by transfected CHO and MDCK cells. In continuous labeling and pulse chase experiments, the secretion of the eLH/CGβ subunit from the transfected CHO cells was inefficient (medium recovery of 16–25%) and slow (t1/2 >6.5 hrs). This indicated that, the secretion of the eLH/CGβ subunit resembles that of hLHβ rather than hCGβ. In MDCK cells grown on Transwell filters, the eLH/CGβ subunit was preferentially secreted from the apical side, similar to the hCGβ subunit secretory route (~65% of the total protein secreted). Taken together, these data suggested that secretion of the eLH/CGβ subunit integrates features of both hLHβ and hCGβ subunits. We propose that the evolution of this intracellular behavior may fulfill the physiological demands for biosynthesis of the eLH/CGβ subunit in the pituitary as well as in the placenta. PMID:25796287

Energy transfer in purple bacterial photosynthetic units from cells grown in various light intensities.

PubMed

Niedzwiedzki, Dariusz M; Gardiner, Alastair T; Blankenship, Robert E; Cogdell, Richard J

2018-05-03

Three photosynthetic membranes, called intra-cytoplasmic membranes (ICMs), from wild-type and the ∆pucBA abce mutant of the purple phototrophic bacterium Rps. palustris were investigated using optical spectroscopy. The ICMs contain identical light-harvesting complex 1-reaction centers (LH1-RC) but have various spectral forms of light-harvesting complex 2 (LH2). Spectroscopic studies involving steady-state absorption, fluorescence, and femtosecond time-resolved absorption at room temperature and at 77 K focused on inter-protein excitation energy transfer. The studies investigated how energy transfer is affected by altered spectral features of the LH2 complexes as those develop under growth at different light conditions. The study shows that LH1 → LH2 excitation energy transfer is strongly affected if the LH2 complex alters its spectroscopic signature. The LH1 → LH2 excitation energy transfer rate modeled with the Förster mechanism and kinetic simulations of transient absorption of the ICMs demonstrated that the transfer rate will be 2-3 times larger for ICMs accumulating LH2 complexes with the classical B800-850 spectral signature (grown in high light) compared to the ICMs from the same strain grown in low light. For the ICMs from the ∆pucBA abce mutant, in which the B850 band of the LH2 complex is blue-shifted and almost degenerate with the B800 band, the LH1 → LH2 excitation energy transfer was not observed nor predicted by calculations.

Phyllosphere Bacterial Community of Floating Macrophytes in Paddy Soil Environments as Revealed by Illumina High-Throughput Sequencing

PubMed Central

Xie, Wan-Ying

2014-01-01

The phyllosphere of floating macrophytes in paddy soil ecosystems, a unique habitat, may support large microbial communities but remains largely unknown. We took Wolffia australiana as a representative floating plant and investigated its phyllosphere bacterial community and the underlying driving forces of community modulation in paddy soil ecosystems using Illumina HiSeq 2000 platform-based 16S rRNA gene sequence analysis. The results showed that the phyllosphere of W. australiana harbored considerably rich communities of bacteria, with Proteobacteria and Bacteroidetes as the predominant phyla. The core microbiome in the phyllosphere contained genera such as Acidovorax, Asticcacaulis, Methylibium, and Methylophilus. Complexity of the phyllosphere bacterial communities in terms of class number and α-diversity was reduced compared to those in corresponding water and soil. Furthermore, the bacterial communities exhibited structures significantly different from those in water and soil. These findings and the following redundancy analysis (RDA) suggest that species sorting played an important role in the recruitment of bacterial species in the phyllosphere. The compositional structures of the phyllosphere bacterial communities were modulated predominantly by water physicochemical properties, while the initial soil bacterial communities had limited impact. Taken together, the findings from this study reveal the diversity and uniqueness of the phyllosphere bacterial communities associated with the floating macrophytes in paddy soil environments. PMID:25362067

Ultra-broadband 2D electronic spectroscopy of carotenoid-bacteriochlorophyll interactions in the LH1 complex of a purple bacterium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maiuri, Margherita; Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544; Réhault, Julien

We investigate the excitation energy transfer (EET) pathways in the photosynthetic light harvesting 1 (LH1) complex of purple bacterium Rhodospirillum rubrum with ultra-broadband two-dimensional electronic spectroscopy (2DES). We employ a 2DES apparatus in the partially collinear geometry, using a passive birefringent interferometer to generate the phase-locked pump pulse pair. This scheme easily lends itself to two-color operation, by coupling a sub-10 fs visible pulse with a sub-15-fs near-infrared pulse. This unique pulse combination allows us to simultaneously track with extremely high temporal resolution both the dynamics of the photoexcited carotenoid spirilloxanthin (Spx) in the visible range and the EET betweenmore » the Spx and the B890 bacterio-chlorophyll (BChl), whose Q{sub x} and Q{sub y} transitions peak at 585 and 881 nm, respectively, in the near-infrared. Global analysis of the one-color and two-color 2DES maps unravels different relaxation mechanisms in the LH1 complex: (i) the initial events of the internal conversion process within the Spx, (ii) the parallel EET from the first bright state S{sub 2} of the Spx towards the Q{sub x} state of the B890, and (iii) the internal conversion from Q{sub x} to Q{sub y} within the B890.« less

Repeated administration of CGP 46381, a gamma-aminobutyric acidB antagonist, and ethosuximide suppresses seizure-associated cyclic adenosine 3'5' monophosphate response element- and activator protein-1 DNA-binding activities in lethargic (lh/lh) mice.

PubMed

Ishige, K; Endo, H; Saito, H; Ito, Y

2001-01-19

To characterize seizure-associated increases in cerebral cortical and thalamic cyclic AMP responsive element (CRE)- and activator protein 1 (AP-1) DNA-binding activities in lethargic (lh/lh) mice, a genetic model of absence seizures, we examined the effects of ethosuximide and CGP 46381 on these DNA-binding activities. Repeated administration (twice a day for 5 days) of ethosuximide (200 mg/kg) or CGP 46381 (60 mg/kg) attenuated both seizure behavior and the increased DNA-binding activities, and was more effective than a single administration of these drugs. These treatments did not affect either normal behavior or basal DNA-binding activities in non-epileptic control (+/+) mice. Gel supershift assays revealed that the increased CRE-binding activity was attributable to activation of the binding activity of CREB, and that the c-Fos-c-Jun complex was a component of the increased AP-1 DNA-binding activity.

Crystal structures of two bacterial HECT-like E3 ligases in complex with a human E2 reveal atomic details of pathogen-host interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, David Yin-wei; Diao, Jianbo; Chen, Jue

2012-12-10

In eukaryotes, ubiquitination is an important posttranslational process achieved through a cascade of ubiquitin-activating (E1), conjugating (E2), and ligase (E3) enzymes. Many pathogenic bacteria deliver virulence factors into the host cell that function as E3 ligases. How these bacterial 'Trojan horses' integrate into the eukaryotic ubiquitin system has remained a mystery. Here we report crystal structures of two bacterial E3s, Salmonella SopA and Escherichia coli NleL, both in complex with human E2 UbcH7. These structures represent two distinct conformational states of the bacterial E3s, supporting the necessary structural rearrangements associated with ubiquitin transfer. The E2-interacting surface of SopA and NleLmore » has little similarity to those of eukaryotic E3s. However, both bacterial E3s bind to the canonical surface of E2 that normally interacts with eukaryotic E3s. Furthermore, we show that a glutamate residue on E3 is involved in catalyzing ubiquitin transfer from E3 to the substrate, but not from E2 to E3. Together, these results provide mechanistic insights into the ubiquitin pathway and a framework for understanding molecular mimicry in bacterial pathogenesis.« less

A review of candidate multilayer insulation systems for potential use on wet-launched LH2 tankage for the Space Exploration Initiative lunar missions

NASA Technical Reports Server (NTRS)

Knoll, Richard H.; Stochl, Robert J.; Sanabria, Rafael

1991-01-01

The storage of cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) for the future Space Exploration Initiative (SEI) will require lightweight, high performance thermal protection systems (TPSs). For the near-term lunar missions, the major weight element for most of the TPSs will be multilayer insulation (MLI) and/or the special structures/systems required to accommodate the MLI. Methods of applying MLI to LH2 tankage to avoid condensation or freezing of condensible gases such as nitrogen or oxygen while in the atmosphere are discussed. Because relatively thick layers of MLI will be required for storage times of a month or more, the transient performance from ground-hold to space-hold of the systems will become important in optimizing the TPSs for many of the missions. The ground-hold performance of several candidate systems are given as well as a qualitative assessment of the transient performance effects.

A review of candidate multilayer insulation systems for potential use on wet-launched LH2 tankage for the space exploration initiative lunar missions

NASA Technical Reports Server (NTRS)

Knoll, Richard H.; Stochl, Robert J.; Sanabria, Rafael

1991-01-01

The storage of cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) for the future Space Exploration Initiative (SEI) will require lightweight, high performance thermal protection systems (TPS's). For the near-term lunar missions, the major weight element for most of the TPS's will be multilayer insulation (MLI) and/or the special structures/systems required to accommodate the MLI. Methods of applying MLI to LH2 tankage to avoid condensation or freezing of condensible gases such as nitrogen or oxygen while in the atmosphere are discussed. Because relatively thick layers of MLI will be required for storage times of a month or more, the transient performance from ground-hold to space-hold of the systems will become important in optimizing the TPS's for many of the missions. The ground-hold performance of several candidate systems are given as well as a qualitative assessment of the transient performance effects.

Vertical Distribution of Bacterial Communities in the Indian Ocean as Revealed by Analyses of 16S rRNA and nasA Genes.

PubMed

Jiang, Xuexia; Jiao, Nianzhi

2016-09-01

Bacteria play an important role in the marine biogeochemical cycles. However, research on the bacterial community structure of the Indian Ocean is scarce, particularly within the vertical dimension. In this study, we investigated the bacterial diversity of the pelagic, mesopelagic and bathypelagic zones of the southwestern Indian Ocean (50.46°E, 37.71°S). The clone libraries constructed by 16S rRNA gene sequence revealed that most phylotypes retrieved from the Indian Ocean were highly divergent from those retrieved from other oceans. Vertical differences were observed based on the analysis of natural bacterial community populations derived from the 16S rRNA gene sequences. Based on the analysis of the nasA gene sequences from GenBank database, a pair of general primers was developed and used to amplify the bacterial nitrate-assimilating populations. Environmental factors play an important role in mediating the bacterial communities in the Indian Ocean revealed by canonical correlation analysis.

The Evolution of Utilizing Manual Throttles to Avoid Excessively Low LH2 NPSP at the SSME Inlet

NASA Technical Reports Server (NTRS)

Henfling, Rick

2011-01-01

In the late 1970s, years before the Space Shuttle flew its maiden voyage, it was understood low liquid hydrogen (LH2) Net Positive Suction Pressure (NPSP) at the inlet to the Space Shuttle Main Engine (SSME) could have adverse effects on engine operation. A number of failures within both the External Tank (ET) and the Orbiter Main Propulsion System (MPS) could result in a low LH2 NPSP condition, which at extremely low levels can result in cavitation of SSME turbomachinery. Operational workarounds were developed to take advantage of the onboard crew s ability to manually throttle down the SSMEs (via the Pilot s Speedbrake/Throttle Controller), which alleviated the low LH2 NPSP condition. Manually throttling the SSME to a lower power level resulted in an increase in NPSP, mainly due to the reduction in frictional flow losses while at the lower throttle setting. Early in the Space Shuttle Program s history, the relevant Flight Rule for the Booster flight controllers in Mission Control did not distinguish between ET and Orbiter MPS failures and the same crew action was taken for both. However, after a review of all Booster operational techniques following the Challenger disaster in the late 1980s, it was determined manually throttling the SSME to a lower power was only effective for Orbiter MPS failures and the Flight Rule was updated to reflect this change. The Flight Rule and associated crew actions initially called for a single throttle step to minimum power level when a low threshold for NPSP was met. As engineers refined their understanding of the NPSP requirements for the SSME (through a robust testing program), the operational techniques evolved to take advantage of the additional capabilities. This paper will examine the evolution of the Flight rule and associated procedure and how increases in knowledge about the SSME and the Space Shuttle vehicle as a whole have helped shape their development. What once was a single throttle step when NPSP decreased to a

The Evolution of Utilizing Manual Throttling to Avoid Excessively Low LH2 NPSP at the SSME Inlet

NASA Technical Reports Server (NTRS)

Henfling, Rick

2010-01-01

In the late 1970s, years before the Space Shuttle flew its maiden voyage, it was understood low liquid hydrogen (LH2) Net Positive Suction Pressure (NPSP) at the inlet to the Space Shuttle Main Engine (SSME) could have adverse effects on engine operation. A number of failures within both the External Tank (ET) and the Orbiter Main Propulsion System (MPS) could result in a low LH2 NPSP condition, which at extremely low levels can result in cavitation of SSME turbomachinery. Operational workarounds were developed to take advantage of the onboard crew s ability to manually throttle down the SSMEs (via the Pilot s Speedbrake/Throttle Controller), which alleviated the low LH2 NPSP condition. Manually throttling the SSME to a lower power level resulted in an increase in NPSP, mainly due to the reduction in frictional flow losses while at the lower throttle setting. Early in the Space Shuttle Program s history, the relevant Flight Rule for the Booster flight controller in Mission Control did not distinguish between ET and Orbiter MPS failures and the same crew action was taken for both. However, after a review of all Booster operational techniques following the Challenger disaster in the late 1980s, it was determined manually throttling the SSME to a lower power was only effective for Orbiter MPS failures and the Flight Rule was updated to reflect this change. The Flight Rule and associated crew actions initially called for a single throttle step to minimum power level when a low threshold for NPSP was met. As engineers refined their understanding of the NPSP requirements for the SSME (through a robust testing program), the operational techniques evolved to take advantage of the additional capabilities. This paper will examine the evolution of the Flight rule and associated procedure and how increases in knowledge about the SSME and the Space Shuttle vehicle as a whole have helped shape their development. What once was a single throttle step when NPSP decreased to a

Pretest analysis document for Semiscale Test S-LH-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, R.A.

Results from various pretest calculations which were performed for Test S-LH-1 are included in this report. Test S-LH-1 has been designed to produce primary liquid holdup in the steam generator U-tubes similar to Tests S-UT-8. The analyses included in this report indicate liquid will be held in the tubes, the core liquid level will be appropriately depressed, and a core heater rod temperature excursion should occur. Several sensitivity studies are also included which identify parameters which could affect the response.

Swabbing of waiting room magazines reveals only low levels of bacterial contamination

PubMed Central

Charnock, Colin

2005-01-01

Previous studies have shown that toys in waiting rooms of general practice surgeries can be contaminated with potentially pathogenic bacteria. The question was raised as to whether magazines might also be sources of contamination. Swabbing of the front page of 15 magazines from 11 general practice surgeries, followed by analysis for total and specific bacteria, revealed low levels of contamination. Among targeted groups of pathogens only two colonies of Staphylococcus aureus were detected. Magazines do not seem to be potentially important vectors of bacterial transfer in the setting examined. PMID:15667764

The effects of Vitex agnus castus extract and its interaction with dopaminergic system on LH and testosterone in male mice.

PubMed

Nasri, Sima; Oryan, Shahrbano; Rohani, Ali Haeri; Amin, Gholam Reza

2007-07-15

The purpose of this study was to evaluate the probable effects of Vitex agnus castus (Vac.) on the male reproductive physiology. It is a well known fact that LH secretion from the anterior pituitary of mammals is controlled by many neurotransmiters such as dopamine. In this experiment, we have studied the effect of Vac. extract on the LH and testosterone hormones and its interaction with the dopaminergic system on male mice. In order to evaluate these effects, we used the hydroalcoholic Vac. extract (for extraction we used percolation technique) injection with the following doses: 65, 165, 265, 365 and 465 mg kg-', bromocriptine as a dopamine receptor agonist (5, 10, 20 mg kg(-1)) and haloperidol as a dopamine receptor antagonist (1, 1.5, 2, 2.5, 3 mg kg(-1)). To study the interaction between Vac. extract and dopaminergic system, we injected the optimum doses of Vac. with bromocriptine or haloperidol at the same time. Intraperitoneal injections were applied in all experiments, once a day for 30 days. The control group remained intact and the sham group received vehicle. After the last injection, we collected the animal blood serums for hormonal assays. LH and testosterone were measured by Radio Immuno Assay (RIA). LH and testosterone, showed significant decrease in bromocriptine group and haloperidol increased these hormones. Vac. extract decreased significantly the LH and testosterone levels. The coadministration of Vac. extract and bromocriptine decreased LH and testosterone. Coadministration of Vac. extract and haloperidol decreased LH and testosterone levels. These results suggest: dopamine regulates the gonadotroph-leydig cells axis. It appears that Vac. exertes effects through dopaminergic system and other pathways. The findings of this study show we can use Vac. extract for pathological cases of increasing LH and testosterone.

Riverine Bacterial Communities Reveal Environmental Disturbance Signatures within the Betaproteobacteria and Verrucomicrobia.

PubMed

Balmonte, John Paul; Arnosti, Carol; Underwood, Sarah; McKee, Brent A; Teske, Andreas

2016-01-01

Riverine bacterial communities play an essential role in the biogeochemical coupling of terrestrial and marine environments, transforming elements and organic matter in their journey from land to sea. However, precisely due to the fact that rivers receive significant terrestrial input, the distinction between resident freshwater taxa vs. land-derived microbes can often become ambiguous. Furthermore, ecosystem perturbations could introduce allochthonous microbial groups and reshape riverine bacterial communities. Using full- and partial-length 16S ribosomal RNA gene sequences, we analyzed the composition of bacterial communities in the Tar River of North Carolina from November 2010 to November 2011, during which a natural perturbation occurred: the inundation of the lower reaches of an otherwise drought-stricken river associated with Hurricane Irene, which passed over eastern North Carolina in late August 2011. This event provided the opportunity to examine the microbiological, hydrological, and geochemical impacts of a disturbance, defined here as the large freshwater influx into the Tar River, superimposed on seasonal changes or other ecosystem variability independent of the hurricane. Our findings demonstrate that downstream communities are more taxonomically diverse and temporally variable than their upstream counterparts. More importantly, pre- vs. post-disturbance taxonomic comparison of the freshwater-dominant Betaproteobacteria class and the phylum Verrucomicrobia reveal a disturbance signature of previously undetected taxa of diverse origins. We use known traits of closely-related taxa to interpret the ecological function of disturbance-associated bacteria, and hypothesize that carbon cycling was enhanced post-disturbance in the Tar River, likely due to the flux of organic carbon into the system associated with the large freshwater pulse. Our analyses demonstrate the importance of geochemical and hydrological alterations in structuring bacterial communities

Phyllosphere bacterial community of floating macrophytes in paddy soil environments as revealed by illumina high-throughput sequencing.

PubMed

Xie, Wan-Ying; Su, Jian-Qiang; Zhu, Yong-Guan

2015-01-01

The phyllosphere of floating macrophytes in paddy soil ecosystems, a unique habitat, may support large microbial communities but remains largely unknown. We took Wolffia australiana as a representative floating plant and investigated its phyllosphere bacterial community and the underlying driving forces of community modulation in paddy soil ecosystems using Illumina HiSeq 2000 platform-based 16S rRNA gene sequence analysis. The results showed that the phyllosphere of W. australiana harbored considerably rich communities of bacteria, with Proteobacteria and Bacteroidetes as the predominant phyla. The core microbiome in the phyllosphere contained genera such as Acidovorax, Asticcacaulis, Methylibium, and Methylophilus. Complexity of the phyllosphere bacterial communities in terms of class number and α-diversity was reduced compared to those in corresponding water and soil. Furthermore, the bacterial communities exhibited structures significantly different from those in water and soil. These findings and the following redundancy analysis (RDA) suggest that species sorting played an important role in the recruitment of bacterial species in the phyllosphere. The compositional structures of the phyllosphere bacterial communities were modulated predominantly by water physicochemical properties, while the initial soil bacterial communities had limited impact. Taken together, the findings from this study reveal the diversity and uniqueness of the phyllosphere bacterial communities associated with the floating macrophytes in paddy soil environments. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Fungal and bacterial successions in the process of co-composting of organic wastes as revealed by 454 pyrosequencing.

PubMed

Galitskaya, Polina; Biktasheva, Liliya; Saveliev, Anatoly; Grigoryeva, Tatiana; Boulygina, Eugenia; Selivanovskaya, Svetlana

2017-01-01

Composting is viewed as one of the primary methods to treat organic wastes. Co-composting may improve the efficiency of this treatment by establishing the most suitable conditions for decomposers than those present in the individual wastes. Given that bacteria and fungi are the driving agents of composting, information about the composition of their communities and dynamics during composting may improve reproducibility, performance and quality of the final compost as well as help to evaluate the potential human health risk and the choice of the most appropriate application procedure. In this study, the co-composting of mixtures containing two similar components (organic fraction of municipal solid waste and sawdust polluted by oil) and one discriminate component (sewage sludges of different origin) were investigated. Bacterial and fungal community successions in the two mixtures were analyzed during the composting process by determining the change in their structural dynamics using qPCR and 454 pyrosequencing methods in a lab experiment for a period of 270 days. During the initial composting stage, the number of 16S bacterial copies was (3.0±0.2) x 106 and (0.4±0.0) x 107 g-1, and the Rhodospiralles and Lactobacialles orders dominated. Fungal communities had (2.9±0.0) x105 and (6.1±0.2) x105 ITS copies g-1, and the Saccharomycetales order dominated. At the end of the thermophilic stage on the 30th day of composting, bacterial and fungal communities underwent significant changes: dominants changed and their relative abundance decreased. Typical compost residents included Flavobacteriales, Chitinophagaceae and Bacterioidetes for bacteria and Microascaceae, Dothideomycetes, Eurotiomycetes, Sordariomycetes, and Agaricomycetes for fungi. During the later composting stages, the dominating taxa of both bacterial and fungal communities remained, while their relative abundance decreased. In accordance with the change in the dominating OTUs, it was concluded that the

Fungal and bacterial successions in the process of co-composting of organic wastes as revealed by 454 pyrosequencing

PubMed Central

Galitskaya, Polina; Saveliev, Anatoly; Grigoryeva, Tatiana; Boulygina, Eugenia; Selivanovskaya, Svetlana

2017-01-01

Composting is viewed as one of the primary methods to treat organic wastes. Co-composting may improve the efficiency of this treatment by establishing the most suitable conditions for decomposers than those present in the individual wastes. Given that bacteria and fungi are the driving agents of composting, information about the composition of their communities and dynamics during composting may improve reproducibility, performance and quality of the final compost as well as help to evaluate the potential human health risk and the choice of the most appropriate application procedure. In this study, the co-composting of mixtures containing two similar components (organic fraction of municipal solid waste and sawdust polluted by oil) and one discriminate component (sewage sludges of different origin) were investigated. Bacterial and fungal community successions in the two mixtures were analyzed during the composting process by determining the change in their structural dynamics using qPCR and 454 pyrosequencing methods in a lab experiment for a period of 270 days. During the initial composting stage, the number of 16S bacterial copies was (3.0±0.2) x 106 and (0.4±0.0) x 107 g-1, and the Rhodospiralles and Lactobacialles orders dominated. Fungal communities had (2.9±0.0) x105 and (6.1±0.2) x105 ITS copies g-1, and the Saccharomycetales order dominated. At the end of the thermophilic stage on the 30th day of composting, bacterial and fungal communities underwent significant changes: dominants changed and their relative abundance decreased. Typical compost residents included Flavobacteriales, Chitinophagaceae and Bacterioidetes for bacteria and Microascaceae, Dothideomycetes, Eurotiomycetes, Sordariomycetes, and Agaricomycetes for fungi. During the later composting stages, the dominating taxa of both bacterial and fungal communities remained, while their relative abundance decreased. In accordance with the change in the dominating OTUs, it was concluded that the

Patterns of LH and FSH in men during high-frequency blood sampling.

PubMed

Scheele, F; Lambalk, C B; Schoemaker, J; van Kessel, H; de Koning, J; van Dieten, J A; van Rees, G P; de Vries Robles-Korsen, T J

1987-07-01

The aim of the study was to test the hypothesis that in serial determinations of concentrations of LH and FSH involving blood samples taken every minute, the observed pulses of LH and FSH which last less than 3-4 min might not be a physiological phenomenon but part of the 'noise' of the radioimmunoassay or blood-sampling technique. Blood was sampled every minute for a period of 90 min in six men. During the first 45 min, blood was sampled by means of vacuum tubes only. During the second 45 min, sampling took place with a syringe via a rubber stopper, either using a tourniquet (n = 3) or flushing the cannula with heparinized saline. Three criteria were used to identify variations in the patterns of LH and FSH as true hormonal changes. First, a threshold was used which had to be exceeded by the difference between nadir and maximum values before a pulse could be identified. An average of approximately six pulses per 90 min was found in both the LH and FSH series. The majority of these pulses lasted less than 3-4 min. In two subjects, larger LH pulses of longer duration were measured. Secondly, differences between duplicate measurements of nadir and/or maximum values of more than one-third of the amplitude of a pulse were considered unacceptable. This involved about 75% of the pulses. Thirdly, the reproducibility of the hormone variations was estimated. In one subject, concentrations of LH were measured four times in four separate assays.(ABSTRACT TRUNCATED AT 250 WORDS)

Multilayer-MCTDH approach to the energy transfer dynamics in the LH2 antenna complex

NASA Astrophysics Data System (ADS)

Shibl, Mohamed F.; Schulze, Jan; Al-Marri, Mohammed J.; Kühn, Oliver

2017-09-01

The multilayer multiconfiguration time-dependent Hartree method is used to study the coupled exciton-vibrational dynamics in a high-dimensional nonameric model of the LH2 antenna complex of purple bacteria. The exciton-vibrational coupling is parametrized within the Huang-Rhys model according to phonon and intramolecular vibrational modes derived from an experimental bacteriochlorophyll spectral density. In contrast to reduced density matrix approaches, the Schrödinger equation is solved explicitly, giving access to the full wave function. This facilitates an unbiased analysis in terms of the coupled dynamics of excitonic and vibrational degrees of freedom. For the present system, we identify spectator modes for the B800 to B800 transfer and we find a non-additive effect of phonon and intramolecular vibrational modes on the B800 to B850 exciton transfer.

Two-photon excitation spectroscopy of carotenoid-containing and carotenoid-depleted LH2 complexes from purple bacteria.

PubMed

Stepanenko, Ilya; Kompanetz, Viktor; Makhneva, Zoya; Chekalin, Sergey; Moskalenko, Andrei; Razjivin, Andrei

2009-08-27

We applied two-photon fluorescence excitation spectroscopy to LH2 complex from purple bacteria Allochromatium minutissimum and Rhodobacter sphaeroides . Bacteriochlorophyll fluorescence was measured under two-photon excitation of the samples within the 1200-1500 nm region. Spectra were obtained for both carotenoid-containing and -depleted complexes of each bacterium to allow their direct comparison. The depletion of carotenoids did not alter the two-photon excitation spectra of either bacteria. The spectra featured a wide excitation band around 1350 nm (2x675 nm, 14,800 cm(-1)) which strongly resembled two-photon fluorescence excitation spectra of similar complexes published by other authors. We consider obtained experimental data to be evidence of direct two-photon excitation of bacteriochlorophyll excitonic states in this spectral region.

Atomistic absorption spectra and non-adiabatic dynamics of the LH2 complex with a GPU-accelerated ab initio exciton model

NASA Astrophysics Data System (ADS)

Glowacki, David

Recently, we outlined an efficient multi-tiered parallel excitonic framework that utilizes time dependent density functional theory (TDDFT) to calculate ground/excited state energies and gradients of large supramolecular complexes in atomistic detail. In this paper, we apply our ab initioexciton framework to the 27 coupled bacteriocholorophyll-a chromophores which make up the LH2 complex, using it to compute linear absorption spectra and short-time, on-the-fly nonadiabatic surface-hopping (SH) dynamics of electronically excited LH2. Our ab initio exciton model includes two key parameters whose values are determined by fitting to experiment: d, which is added to the diagonal elements, corrects for the error in TDDFT vertical excitation energies on a single chromophore; and e, which occurs on the off-diagonal matrix elements, describes the average dielectric screening of the inter-chromophore transition-dipole coupling. Using snapshots obtained from equilibrium molecular dynamics simulations (MD) of LH2, best-fit values of both d and e were obtained by fitting to the thermally broadened experimental absorption spectrum within the Frank-Condon approximation, providing a linear absorption spectrum that agrees reasonably well with the experimental observations. We follow the nonadiabatic dynamics using surface hopping to construct time-resolved visualizations of the EET dynamics in the sub-picosecond regime following photoexcitation. This provides some qualitative insight into the excitonic energy transfer (EET) that results from atomically resolved vibrational fluctuations of the chromophores. The dynamical picture that emerges is one of rapidly fluctuating eigenstates that are delocalized over multiple chromophores and undergo frequent crossing on a femtosecond timescale as a result of the underlying chromophore vibrational dynamics. The eigenstate fluctuations arise from disorder in both the diagonal chromophore site energies and the off-diagonal inter

Optimal fold symmetry of LH2 rings on a photosynthetic membrane

PubMed Central

Cleary, Liam; Chen, Hang; Chuang, Chern; Silbey, Robert J.; Cao, Jianshu

2013-01-01

An intriguing observation of photosynthetic light-harvesting systems is the N-fold symmetry of light-harvesting complex 2 (LH2) of purple bacteria. We calculate the optimal rotational configuration of N-fold rings on a hexagonal lattice and establish two related mechanisms for the promotion of maximum excitation energy transfer (EET). (i) For certain fold numbers, there exist optimal basis cells with rotational symmetry, extendable to the entire lattice for the global optimization of the EET network. (ii) The type of basis cell can reduce or remove the frustration of EET rates across the photosynthetic network. We find that the existence of a basis cell and its type are directly related to the number of matching points S between the fold symmetry and the hexagonal lattice. The two complementary mechanisms provide selection criteria for the fold number and identify groups of consecutive numbers. Remarkably, one such group consists of the naturally occurring 8-, 9-, and 10-fold rings. By considering the inter-ring distance and EET rate, we demonstrate that this group can achieve minimal rotational sensitivity in addition to an optimal packing density, achieving robust and efficient EET. This corroborates our findings i and ii and, through their direct relation to S, suggests the design principle of matching the internal symmetry with the lattice order. PMID:23650366

Optimal fold symmetry of LH2 rings on a photosynthetic membrane.

PubMed

Cleary, Liam; Chen, Hang; Chuang, Chern; Silbey, Robert J; Cao, Jianshu

2013-05-21

An intriguing observation of photosynthetic light-harvesting systems is the N-fold symmetry of light-harvesting complex 2 (LH2) of purple bacteria. We calculate the optimal rotational configuration of N-fold rings on a hexagonal lattice and establish two related mechanisms for the promotion of maximum excitation energy transfer (EET). (i) For certain fold numbers, there exist optimal basis cells with rotational symmetry, extendable to the entire lattice for the global optimization of the EET network. (ii) The type of basis cell can reduce or remove the frustration of EET rates across the photosynthetic network. We find that the existence of a basis cell and its type are directly related to the number of matching points S between the fold symmetry and the hexagonal lattice. The two complementary mechanisms provide selection criteria for the fold number and identify groups of consecutive numbers. Remarkably, one such group consists of the naturally occurring 8-, 9-, and 10-fold rings. By considering the inter-ring distance and EET rate, we demonstrate that this group can achieve minimal rotational sensitivity in addition to an optimal packing density, achieving robust and efficient EET. This corroborates our findings i and ii and, through their direct relation to S, suggests the design principle of matching the internal symmetry with the lattice order.

Extreme supernova models for the super-luminous transient ASASSN-15LH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatzopoulos, Emmanouil; Wheeler, John C.; Vinko, J.

The recent discovery of the unprecedentedly super-luminous transient ASASSN-15lh (or SN 2015L) with its UV-bright secondary peak challenges all the power-input models that have been proposed for super-luminous supernovae. Here we examine some of the few viable interpretations of ASASSN-15lh in the context of a stellar explosion, involving combinations of one or more power inputs. We model the light curve of ASASSN-15lh with a hybrid model that includes contributions from magnetar spin-down energy and hydrogen-poor circumstellar interaction. We also investigate models of pure circumstellar interaction with a massive hydrogen-deficient shell and discuss the lack of interaction features in the observedmore » spectra. We find that, as a supernova, ASASSN-15lh can be best modeled by the energetic core-collapse of an ~40 M ⊙ star interacting with a hydrogen-poor shell of ~20 M ⊙. The circumstellar shell and progenitor mass are consistent with a rapidly rotating pulsational pair-instability supernova progenitor as required for strong interaction following the final supernova explosion. Additional energy injection by a magnetar with an initial period of 1–2 ms and magnetic field of 0.1–1 × 10 14 G may supply the excess luminosity required to overcome the deficit in single-component models, but this requires more fine-tuning and extreme parameters for the magnetar, as well as the assumption of efficient conversion of magnetar energy into radiation. As a result, we thus favor a single-input model where the reverse shock formed in a strong SN ejecta–circumstellar matter interaction following a very powerful core-collapse SN explosion can supply the luminosity needed to reproduce the late-time UV-bright plateau.« less

Extreme supernova models for the super-luminous transient ASASSN-15LH

DOE PAGES

Chatzopoulos, Emmanouil; Wheeler, John C.; Vinko, J.; ...

2016-09-07

The recent discovery of the unprecedentedly super-luminous transient ASASSN-15lh (or SN 2015L) with its UV-bright secondary peak challenges all the power-input models that have been proposed for super-luminous supernovae. Here we examine some of the few viable interpretations of ASASSN-15lh in the context of a stellar explosion, involving combinations of one or more power inputs. We model the light curve of ASASSN-15lh with a hybrid model that includes contributions from magnetar spin-down energy and hydrogen-poor circumstellar interaction. We also investigate models of pure circumstellar interaction with a massive hydrogen-deficient shell and discuss the lack of interaction features in the observedmore » spectra. We find that, as a supernova, ASASSN-15lh can be best modeled by the energetic core-collapse of an ~40 M ⊙ star interacting with a hydrogen-poor shell of ~20 M ⊙. The circumstellar shell and progenitor mass are consistent with a rapidly rotating pulsational pair-instability supernova progenitor as required for strong interaction following the final supernova explosion. Additional energy injection by a magnetar with an initial period of 1–2 ms and magnetic field of 0.1–1 × 10 14 G may supply the excess luminosity required to overcome the deficit in single-component models, but this requires more fine-tuning and extreme parameters for the magnetar, as well as the assumption of efficient conversion of magnetar energy into radiation. As a result, we thus favor a single-input model where the reverse shock formed in a strong SN ejecta–circumstellar matter interaction following a very powerful core-collapse SN explosion can supply the luminosity needed to reproduce the late-time UV-bright plateau.« less

LH2 tank pressure control by thermodynamic vent system (TVS) at zero gravity

NASA Astrophysics Data System (ADS)

Wang, B.; Huang, Y. H.; Chen, Z. C.; Wu, J. Y.; Li, P.; Sun, P. J.

2017-02-01

Thermodynamic vent system (TVS) is employed for pressure control of propellant tanks at zero gravity. An analytical lumped parameter model is developed to predict pressure variation in an 18.09 m3 liquid hydrogen tank equipped with TVS. Mathematical simulations are carried out assuming tank is filled up to 75% volume (liquid mass equals to 945 kg) and is subjected to heat flux of 0.76 W/m2. Tank pressure controls at 165.5-172.4, 165.5-179.3 and 165.5-182.2 kPa are compared with reference to number of vent cycles, vent duration per cycle and loss of hydrogen. Analysis results indicate that the number of vent cycles significantly decreases from 62 to 21 when tank pressure control increases from 6.9 to 20.4 kPa. Also, duration of vent cycle increases from 63 to 152 and cycle duration decreases from 3920 to 3200 s. Further, the analysis result suggests that LH2 evaporation loss per day decreases from 0.17 to 0.14%. Based on the results of analysis, TVS is found effective in controlling the propellant tank pressure in zero gravity.

Parallel electron force balance and the L-H transition

DOE PAGES

Stoltzfus-Dueck, T.

2016-05-23

In one popular paradigm for the L-H transition, energy transfer to the mean flows directly depletes turbulence fluctuation energy, resulting in suppression of the turbulence and a corresponding transport bifurcation. To quantitatively evaluate this mechanism, one must remember that electron parallel force balance couples nonzonal velocity fluctuations with electron pressure fluctuations on rapid timescales, comparable with the electron transit time. For this reason, energy in the nonzonal velocity stays in a fairly fixed ratio to the free energy in electron density fluctuations, at least for frequency scales much slower than electron transit. Furthermore, in order for direct depletion of themore » energy in turbulent fluctuations to cause the L-H transition, energy transfer via Reynolds stress must therefore drain enough energy to significantly reduce the sum of the free energy in nonzonal velocities and electron pressure fluctuations. At low k⊥, the electron thermal free energy is much larger than the energy in nonzonal velocities, posing a stark challenge for this model of the L-H transition.« less

Evolution of Edge Pedestal Profiles Over the L-H Transition

NASA Astrophysics Data System (ADS)

Sayer, M. S.; Stacey, W. M.; Floyd, J. P.; Groebner, R. J.

2012-10-01

The detailed time evolution of thermal diffusivities, electromagnetic forces, pressure gradients, particle pinch and momentum transport frequencies (which determine the diffusion coefficient) have been analyzed during the L-H transition in a DIII-D discharge. Density, temperature, rotation velocity and electric field profiles at times just before and after the L-H transition are analyzed in terms of these quantities. The analysis is based on the fluid particle balance, energy balance, force balance and heat conduction equations, as in Ref. [1], but with much greater time resolution and with account for thermal ion orbit loss. The variation of diffusive and non-diffusive transport over the L-H transition is determined from the variation in the radial force balance (radial electric field, VxB force, and pressure gradient) and the variation in the interpreted diffusive transport coefficients. 6pt [1] W.M. Stacey and R.J. Groebner, Phys. Plasmas 17, 112512 (2010).

Accelerated Episodic LH Release Accompanies Blunted Progesterone Regulation in PCOS-like Female Rhesus Monkeys (Macaca mulatta) Exposed to Testosterone During Early-to-Mid Gestation.

PubMed

Abbott, David H; Vepraskas, Sarah H; Horton, Teresa H; Terasawa, Ei; Levine, Jon E

2018-06-15

Ovarian theca cell hyperandrogenism in women with PCOS is compounded by androgen receptor-mediated impairment of estradiol and progesterone negative feedback regulation of episodic LH release. The resultant LH hypersecretion, likely the product of accelerated episodic release of GnRH from the median eminence of the hypothalamus, hyperstimulates ovarian theca cell steroidogenesis, enabling testosterone (T) and androstenedione excess. Prenatally androgenized female monkeys (PA) exposed to fetal male levels of T during early-to-mid gestation, when adult, demonstrate PCOS-like traits, including high T and LH levels. This study tests the hypothesis that progesterone resistance-associated acceleration in episodic LH release contributes to PA monkey LH excess. 4 PA and 3 regularly cycling, healthy control adult female rhesus monkeys of comparable age and body mass index underwent (1) a 10 h, frequent intravenous sampling assessment for LH episodic release, immediately followed by (2) IV infusion of exogenous GnRH to quantify continuing pituitary LH responsiveness, and subsequently (3) an SC injection of a progesterone receptor antagonist, mifepristone, to examine LH responses to blockade of progesterone-mediated action. Compared to controls, the relatively hyperandrogenic PA females exhibited ~100% increase (p = 0.037) in LH pulse frequency, positive correlation of LH pulse amplitude (p = 0.017) with androstenedione, ~100% greater increase (p = 0.034) in acute (0--10 min) LH responses to exogenous GnRH, and an absence (p = 0.008) of modest LH elevation following acute progesterone receptor blockade suggestive of diminished progesterone negative feedback. Such dysregulation of LH release in PCOS-like monkeys implicates impaired feedback control of episodic release of hypothalamic GnRH reminiscent of PCOS neuroendocrinopathy. 2018 S. Karger AG, Basel.

Effects of nesfatin-1 on food intake and LH secretion in prepubertal gilts and genomic association of the porcine NUCB2 gene with growth traits

USDA-ARS?s Scientific Manuscript database

Nesfatin-1, a product of the nucleobindin 2 (NUCB2) gene, purportedly plays important roles in whole-body energy homeostasis. Experiments were conducted to determine how NUCB2 expression in fat depots may be controlled in the pig and to test the hypothesis that nesfatin-1 regulates appetite and LH s...

Male sexual behavior contributes to the maintenance of high LH pulsatility in anestrous female goats.

PubMed

Vielma, Jesús; Chemineau, Philippe; Poindron, Pascal; Malpaux, Benoît; Delgadillo, José Alberto

2009-10-01

The objective of this study was to determine the importance of male sexual behavior in stimulating LH secretion in anovulatory female goats. Two groups of females (n=10 per group) were each exposed to a buck in sexual rest and submitted to natural daylength. In one group, the buck was awake, whereas in the other group, it was sedated to prevent its sexual behavior. Two other groups of goats (n=10 per group) were exposed to sexually active bucks that had been exposed to 2.5 months of long days. In one group, the buck was awake, and in the other group, it was sedated. LH secretion was determined every 15 min from 4 h before introducing the bucks to 8 h after, then every 15 min again from 20 to 24 h after introducing the bucks. The bucks submitted to natural daylength did not stimulate LH secretion (P>0.05), whether they were sedated or not. In contrast, both the awake and the sedated light-treated bucks induced an increase (P<0.05) of LH pulsatility in the first 4 h following their introduction. However, pulsatility remained elevated until 24 h in the females exposed to the light-treated awake buck, whereas in the group with the light-treated sedated buck, pulsatility diminished (P<0.05) after the first 4 h of stimulation by the buck. In conclusion, the sexual behavior of males contributes to the maintenance of a high LH pulsatility up to 24 h after introduction into a group of anovulatory goats.

A Computational Method for Determining the Equilibrium Composition and Product Temperature in a LH2/LOX Combustor

NASA Technical Reports Server (NTRS)

Sozen, Mehmet

2003-01-01

In what follows, the model used for combustion of liquid hydrogen (LH2) with liquid oxygen (LOX) using chemical equilibrium assumption, and the novel computational method developed for determining the equilibrium composition and temperature of the combustion products by application of the first and second laws of thermodynamics will be described. The modular FORTRAN code developed as a subroutine that can be incorporated into any flow network code with little effort has been successfully implemented in GFSSP as the preliminary runs indicate. The code provides capability of modeling the heat transfer rate to the coolants for parametric analysis in system design.

Subtle spectral effects accompanying the assembly of bacteriochlorophylls into cyclic light harvesting complexes revealed by high-resolution fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Rätsep, Margus; Pajusalu, Mihkel; Linnanto, Juha Matti; Freiberg, Arvi

2014-10-01

We have observed that an assembly of the bacteriochloropyll a molecules into B850 and B875 groups of cyclic bacterial light-harvesting complexes LH2 and LH1, respectively, results an almost total loss of the intra-molecular vibronic structure in the fluorescence spectrum, and simultaneously, an essential enhancement of its phonon sideband due to electron-phonon coupling. While the suppression of the vibronic coupling in delocalized (excitonic) molecular systems is predictable, as also confirmed by our model calculations, a boost of the electron-phonon coupling is rather unexpected. The latter phenomenon is explained by exciton self-trapping, promoted by mixing the molecular exciton states with charge transfer states between the adjacent chromophores in the tightly packed B850 and B875 arrangements. Similar, although less dramatic trends were noted for the light-harvesting complexes containing chlorophyll pigments.

Exploring bacterial infections: theoretical and experimental studies of the bacterial population dynamics and antibiotic treatment

NASA Astrophysics Data System (ADS)

Shao, Xinxian

Bacterial infections are very common in human society. Thus extensive research has been conducted to reveal the molecular mechanisms of the pathogenesis and to evaluate the antibiotics' efficacy against bacteria. Little is known, however, about the population dynamics of bacterial populations and their interactions with the host's immune system. In this dissertation, a stochatic model is developed featuring stochastic phenotypic switching of bacterial individuals to explain the single-variant bottleneck discovered in multi strain bacterial infections. I explored early events in a bacterial infection establishment using classical experiments of Moxon and Murphy on neonatal rats. I showed that the minimal model and its simple variants do not work. I proposed modifications to the model that could explain the data quantitatively. The bacterial infections are also commonly established in physical structures, as biofilms or 3-d colonies. In contrast, most research on antibiotic treatment of bacterial infections has been conducted in well-mixed liquid cultures. I explored the efficacy of antibiotics to treat such bacterial colonies, a broadly applicable method is designed and evaluated where discrete bacterial colonies on 2-d surfaces were exposed to antibiotics. I discuss possible explanations and hypotheses for the experimental results. To verify these hypotheses, we investigated the dynamics of bacterial population as 3-d colonies. We showed that a minimal mathematical model of bacterial colony growth in 3-d was able to account for the experimentally observed presence of a diffusion-limited regime. The model further revealed highly loose packing of the cells in 3-d colonies and smaller cell sizes in colonies than plancktonic cells in corresponding liquid culture. Further experimental tests of the model predictions have revealed that the ratio of the cell size in liquid culture to that in colony cultures was consistent with the model prediction, that the dead cells

Human LH and hCG stimulate differently the early signalling pathways but result in equal testosterone synthesis in mouse Leydig cells in vitro.

PubMed

Riccetti, Laura; De Pascali, Francesco; Gilioli, Lisa; Potì, Francesco; Giva, Lavinia Beatrice; Marino, Marco; Tagliavini, Simonetta; Trenti, Tommaso; Fanelli, Flaminia; Mezzullo, Marco; Pagotto, Uberto; Simoni, Manuela; Casarini, Livio

2017-01-05

Human luteinizing hormone (LH) and chorionic gonadotropin (hCG) are glycoprotein hormones regulating development and reproductive functions by acting on the same receptor (LHCGR). We compared the LH and hCG activity in gonadal cells from male mouse in vitro, i.e. primary Leydig cells, which is a common tool used for gonadotropin bioassay. Murine Leydig cells are naturally expressing the murine LH receptor (mLhr), which binds human LH/hCG. Cultured Leydig cells were treated by increasing doses of recombinant LH and hCG, and cell signaling, gene expression and steroid synthesis were evaluated. We found that hCG is about 10-fold more potent than LH in cAMP recruitment, and slightly but significantly more potent on cAMP-dependent Erk1/2 phosphorylation. However, no significant differences occur between LH and hCG treatments, measured as activation of downstream signals, such as Creb phosphorylation, Stard1 gene expression and testosterone synthesis. These data demonstrate that the responses to human LH/hCG are only quantitatively and not qualitatively different in murine cells, at least in terms of cAMP and Erk1/2 activation, and equal in activating downstream steroidogenic events. This is at odds with what we previously described in human primary granulosa cells, where LHCGR mediates a different pattern of signaling cascades, depending on the natural ligand. This finding is relevant for gonadotropin quantification used in the official pharmacopoeia, which are based on murine, in vivo bioassay and rely on the evaluation of long-term, testosterone-dependent effects mediated by rodent receptor.

Thermal Design of Vapor Cooling of Flight Vehicle Structures Using LH2 Boil-Off

NASA Technical Reports Server (NTRS)

Wang, Xiao-Yen; Zoeckler, Joseph

2015-01-01

Using hydrogen boil-off vapor to cool the structure of a flight vehicle cryogenic upper stage can reduce heat loads to the stage and increase the usable propellant in the stage or extend the life of the stage. The hydrogen vapor can be used to absorb incoming heat as it increases in temperature before being vented overboard. In theory, the amount of heat leaking into the hydrogen tank from the structure will be reduced if the structure is cooled using the propellant boil-off vapor. However, the amount of boil-off vapor available to be used for cooling and the reduction in heat leak to the propellant tank are dependent to each other. The amount of heat leak reduction to the LH2 tank also depends on the total heat load on the stage and the vapor cooling configurations.

Recent Advances in LOX / LH2 Propulsion System for Reusable Vehicle Testing

NASA Astrophysics Data System (ADS)

Tokudome, Shinichiro; Naruo, Yoshihiro; Yagishita, Tsuyoshi; Nonaka, Satoshi; Shida, Maki; Mori, Hatsuo; Nakamura, Takeshi

The third-generation vehicle RVT#3 equipped with a pressure-fed engine, which had upgraded in terms of durability enhancement and a LH2 tank of composite material, successfully performed in repeated flight operation tests; and the vehicle reached its maximum flying altitude of 42m in October 2003. The next step for demonstrating entire sequence of full-scale operation is to put a turbopump-fed system into propulsion system. From a result of primary system analysis, we decided to build an expander-cycle engine by diverting a pair of turbopumps, which had built for another research program, to the present study. A combustion chamber with long cylindrical portion adapted to the engine cycle was also newly made. Two captive firing tests have been conducted with two different thrust control methods, following the component tests of combustor and turbopumps separately conducted. A considerable technical issues recognized in the tests were the robustness enhancement of shaft seal design, the adjustment of shaft stiffness, and start-up operation adapted to the specific engine system. Experimental study of GOX/GH2 RCS thrusters have also been started as a part of a conceptual study of the integration of the propulsion system associated with simplification and reliability improvement of the vehicle system.

Molecular assessment of microbiota structure and dynamics along mixed olive oil and winery wastewaters biotreatment.

PubMed

Eusébio, Ana; Tacão, Marta; Chaves, Sandra; Tenreiro, Rogério; Almeida-Vara, Elsa

2011-07-01

The major parcel of the degradation occurring along wastewater biotreatments is performed either by the native microbiota or by added microbial inocula. The main aim of this study was to apply two fingerprinting methods, temperature gradient gel electrophoresis (TGGE) and length heterogeneity-PCR (LH-PCR) analysis of 16S rRNA gene fragments, in order to assess the microbiota structure and dynamics during mixed olive oil and winery wastewaters aerobic biotreatment performed in a jet-loop reactor (JLR). Sequence homology analysis showed the presence of bacterial genera Gluconacetobacter, Klebsiella, Lactobacillus, Novosphingobium, Pseudomonas, Prevotella, Ralstonia, Sphingobium and Sphingomonas affiliated with five main phylogenetic groups: alpha-, beta- and gamma-Proteobacteria, Firmicutes and Bacteroidetes. LH-PCR analysis distinguished eight predominant DNA fragments correlated with the samples showing highest performance (COD removal rates of 67 up to 75%). Cluster analysis of both TGGE and LH-PCR fingerprinting profiles established five main clusters, with similarity coefficients higher than 79% (TGGE) and 62% (LH-PCR), and related with hydraulic retention time, indicating that this was the main factor responsible for the shifts in the microbiota structure. Canonical correspondence analysis revealed that changes observed on temperature and O(2) level were also responsible for shifts in microbiota composition. Community level metabolic profile analysis was used to test metabolic activities in samples. Integrated data revealed that the microbiota structure corresponds to bacterial groups with high degradative potential and good suitability for this type of effluents biotreatments.

ASASSN-15LH: A SUPERLUMINOUS ULTRAVIOLET REBRIGHTENING OBSERVED BY SWIFT AND HUBBLE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Peter J.; Yang, Yi; Wang, Lifan

2016-09-01

We present and discuss ultraviolet and optical photometry from the Ultraviolet/Optical Telescope, X-ray limits from the X-Ray Telescope on Swift, and imaging polarimetry and ultraviolet/optical spectroscopy with the Hubble Space Telescope , all from observations of ASASSN-15lh. It has been classified as a hydrogen-poor superluminous supernova (SLSN I), making it more luminous than any other supernova observed. ASASSN-15lh is not detected in the X-rays in individual or co-added observations. From the polarimetry we determine that the explosion was only mildly asymmetric. We find the flux of ASASSN-15lh to increase strongly into the ultraviolet, with an ultraviolet luminosity 100 times greatermore » than the hydrogen-rich, ultraviolet-bright SLSN II SN 2008es. We find that objects as bright as ASASSN-15lh are easily detectable beyond redshifts of ∼4 with the single-visit depths planned for the Large Synoptic Survey Telescope. Deep near-infrared surveys could detect such objects past a redshift of ∼20, enabling a probe of the earliest star formation. A late rebrightening—most prominent at shorter wavelengths—is seen about two months after the peak brightness, which is itself as bright as an SLSN. The ultraviolet spectra during the rebrightening are dominated by the continuum without the broad absorption or emission lines seen in SLSNe or tidal disruption events (TDEs) and the early optical spectra of ASASSN-15lh. Our spectra show no strong hydrogen emission, showing only Ly α absorption near the redshift previously found by optical absorption lines of the presumed host. The properties of ASASSN-15lh are extreme when compared to either SLSNe or TDEs.« less

Endocrine correlates of reproduction in the wolf. I. Serum progesterone, estradiol and LH during the estrous cycle

USGS Publications Warehouse

Seal, U.S.; Plotka, E.D.; Packard, J.M.; Mech, L.D.

1979-01-01

The estrous cycle of 10 intact female wolves, aged 8 months-8 years at the initiation of the study, was characterized in terms of vaginal smears, behavioral observations and serum concentrations of estradiol-17β, progesterone and luteinizing hormone (LH) from January through June. No estrous cycles occurred in these animals between June and December. All were housed with male wolves. Two pups and 1 adult remained anestrous during this interval. One pup and 2 adults produced litters between May 4-6. Four adults exhibited endocrine changes similar to those of the pregnant animals but no litters or signs of abortion were observed. The duration of proestrus was 15.7 ± 1.6 days (X ± SEM, n = 6), of estrus 9.0 ± 1.2 days (n = 4) and of the luteal phase 63 ± 2 days (n = 6). The duration of pregnancy was between 60-65 days. The anestrous females (86 blood samples) had 6 progesterone values between 1-2 ng/ml and the remainder below 1 ng/ml. Their estradiol-17β concentrations varied between 5-20 pg/ml. Values for LH varied between 0.1-2 ng/ml, except for 1 value above 15 ng/ml for each of the 2 anestrous pups on 12 January.The 7 estrous animals (260 samples) included 1 pup and 2 adults that delivered litters. Estradiol-17β varied between 10-20 pg/ml during proestrus, peaked at 30-70 pg/ml late in proestrus and fluctuated between 10-30 pg/ml during pregnancy or the duration of luteal activity in the nonpregnant animals. The preovulatory LH rise, 5-15 ng/ml, extended over 3 days during and immediately following the peak estradiol-17β values. An earlier elevation in LH was observed in 3 of the estrous animals. Progesterone began increasing during the LH surge and peaked 11-14 days later at 22-40 ng/ml. Progesterone concentrations greater than 3 ng/ml were maintained for 56-68 days in 6 of the 7 animals exhibiting estrus. Progesterone concentrations declined at parturition but continued to fluctuate between 0.2-3 ng/ml for 3-6 weeks.

Whole brain-pituitary in vitro preparation of the transgenic medaka (Oryzias latipes) as a tool for analyzing the differential regulatory mechanisms of LH and FSH release.

PubMed

Karigo, Tomomi; Aikawa, Masato; Kondo, Chika; Abe, Hideki; Kanda, Shinji; Oka, Yoshitaka

2014-02-01

Two types of gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), are important pituitary hormones for sexual maturation and reproduction, and both of them are centrally regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. In mammals, these two gonadotropins are secreted from a single type of gonadotrope. The mechanisms of differential regulation by GnRH of the release of two types of gonadotropins with different secretory profiles are still unknown. In teleosts, however, LH and FSH are secreted from separate cellular populations, unlike in mammals. This feature makes them useful for studying the regulatory mechanisms of LH and FSH secretions independently. Here, we generated transgenic medaka lines that express Ca(2+) indicator protein, inverse-pericam, specifically in the LH or FSH cells. We performed cell-type-specific Ca(2+) imaging of LH and FSH cells, respectively, using the whole brain-pituitary preparations of these transgenic fish in which all neural circuits and GnRH neuronal projection to the pituitary are kept intact. LH and FSH cells showed different Ca(2+) responses to GnRH. The results suggest differential regulation mechanisms for LH and FSH release by GnRH. Moreover, we also succeeded in detecting the effect on LH cells of endogenous GnRH peptide, which was released by electrical stimulation of the axons of GnRH1 neurons. Thus, our newly developed experimental model system using the whole brain-pituitary in vitro preparation of the transgenic medaka is a powerful tool for analyzing the differential regulatory mechanisms of the release of LH and FSH by multisynaptic neural inputs to the pituitary.

Fluorescent chemosensor based on sensitive Schiff base for selective detection of Zn2+

NASA Astrophysics Data System (ADS)

Singh, T. Sanjoy; Paul, Pradip C.; Pramanik, Harun A. R.

2014-03-01

A Schiff-base fluorescent compound - N, N‧-bis(salicylidene)-1,2 - phenylenediamine (LH2) was synthesized and evaluated as a chemoselective Zn2+ sensor. Addition of Zn2+ to ethanol solution of LH2 resulted in a red shift with a pronounced enhancement in the fluorescence intensity. Moreover, other common alkali, alkaline earth and transition metal ions failed to induce response or minimal spectral changes. Notably, this chemosensor could distinguish clearly Zn2+ from Cd2+. Fluorescence studies on free Schiff base ligand LH2 and LH2 - Zn2+ complex reveal that the quantum yield strongly increases upon coordination. The stoichiometric ratio and association constant were evaluated using Benesi - Hildebrand relation giving 1:1 stoichiometry. This further corroborated 1:1 complex formation based on Job's plot analyses.

LH prevents cisplatin-induced apoptosis in oocytes and preserves female fertility in mouse.

PubMed

Rossi, Valerio; Lispi, Monica; Longobardi, Salvatore; Mattei, Maurizio; Rella, Francesca Di; Salustri, Antonietta; De Felici, Massimo; Klinger, Francesca G

2017-01-01

Premature ovarian failure and female infertility are frequent side effects of anticancer therapies, owing to the extreme sensitivity of the ovarian reserve oocytes to the damaging effects of irradiation and chemotherapy on DNA. We report here a robust protective effect of luteinizing hormone (LH) on the primordial follicle pool of prepubertal ovaries against the cisplatin (Cs)-induced apoptosis. In vitro LH treatment of prepubertal ovarian fragments generated anti-apoptotic signals by a subset of ovarian somatic cells expressing LH receptor (LHR) through cAMP/PKA and Akt pathways. Such signals, reducing the oocyte level of pro-apoptotic TAp63 protein and favoring the repair of the Cs-damaged DNA in the oocytes, prevented their apoptosis. Noteworthy, in vivo administration to prepubertal female mice of a single dose of LH together with Cs inhibited the depletion of the primordial follicle reserve caused by the drug and preserved their fertility in reproductive age, preventing significant alteration in the number of pregnancy and of delivered pups. In conclusion, these findings establish a novel ovoprotective role for LH and further support the very attracting prospective to use physiological 'fertoprotective' approaches for preventing premature infertility and risks linked to precocious menopause in young patients who survived cancer after chemotherapy.

LH prevents cisplatin-induced apoptosis in oocytes and preserves female fertility in mouse

PubMed Central

Rossi, Valerio; Lispi, Monica; Longobardi, Salvatore; Mattei, Maurizio; Rella, Francesca Di; Salustri, Antonietta; De Felici, Massimo; Klinger, Francesca G

2017-01-01

Premature ovarian failure and female infertility are frequent side effects of anticancer therapies, owing to the extreme sensitivity of the ovarian reserve oocytes to the damaging effects of irradiation and chemotherapy on DNA. We report here a robust protective effect of luteinizing hormone (LH) on the primordial follicle pool of prepubertal ovaries against the cisplatin (Cs)-induced apoptosis. In vitro LH treatment of prepubertal ovarian fragments generated anti-apoptotic signals by a subset of ovarian somatic cells expressing LH receptor (LHR) through cAMP/PKA and Akt pathways. Such signals, reducing the oocyte level of pro-apoptotic TAp63 protein and favoring the repair of the Cs-damaged DNA in the oocytes, prevented their apoptosis. Noteworthy, in vivo administration to prepubertal female mice of a single dose of LH together with Cs inhibited the depletion of the primordial follicle reserve caused by the drug and preserved their fertility in reproductive age, preventing significant alteration in the number of pregnancy and of delivered pups. In conclusion, these findings establish a novel ovoprotective role for LH and further support the very attracting prospective to use physiological 'fertoprotective' approaches for preventing premature infertility and risks linked to precocious menopause in young patients who survived cancer after chemotherapy. PMID:27689876

Estrogen Modulates Specific Life and Death Signals Induced by LH and hCG in Human Primary Granulosa Cells In Vitro.

PubMed

Casarini, Livio; Riccetti, Laura; De Pascali, Francesco; Gilioli, Lisa; Marino, Marco; Vecchi, Eugenia; Morini, Daria; Nicoli, Alessia; La Sala, Giovanni Battista; Simoni, Manuela

2017-04-28

Luteinizing hormone (LH) and human chorionic gonadotropin (hCG) are glycoprotein hormones used for assisted reproduction acting on the same receptor (LHCGR) and mediating different intracellular signaling. We evaluated the pro- and anti-apoptotic effect of 100 pM LH or hCG, in the presence or in the absence of 200 pg/mL 17β-estradiol, in long-term, serum-starved human primary granulosa cells (hGLC) and a transfected granulosa cell line overexpressing LHCGR (hGL5/LHCGR). To this purpose, phospho-extracellular-regulated kinase 1/2 (pERK1/2), protein kinase B (pAKT), cAMP-responsive element binding protein (pCREB) activation and procaspase 3 cleavage were evaluated over three days by Western blotting, along with the expression of target genes by real-time PCR and cell viability by colorimetric assay. We found that LH induced predominant pERK1/2 and pAKT activation STARD1 , CCND2 and anti-apoptotic XIAP gene expression, while hCG mediated more potent CREB phosphorylation, expression of CYP19A1 and procaspase 3 cleavage than LH. Cell treatment by LH is accompanied by increased (serum-starved) cell viability, while hCG decreased the number of viable cells. The hCG-specific, pro-apoptotic effect was blocked by a physiological dose of 17β-estradiol, resulting in pAKT activation, lack of procaspase 3 cleavage and increased cell viability. These results confirm that relatively high levels of steroidogenic pathway activation are linked to pro-apoptotic signals in vitro, which may be counteracted by other factors, i.e., estrogens.

Direct analysis by time-of-flight secondary ion mass spectrometry reveals action of bacterial laccase-mediator systems on both hardwood and softwood samples.

PubMed

Goacher, Robyn E; Braham, Erick J; Michienzi, Courtney L; Flick, Robert M; Yakunin, Alexander F; Master, Emma R

2017-12-29

The modification and degradation of lignin play a vital role in carbon cycling as well as production of biofuels and bioproducts. The possibility of using bacterial laccases for the oxidation of lignin offers a route to utilize existing industrial protein expression techniques. However, bacterial laccases are most frequently studied on small model compounds that do not capture the complexity of lignocellulosic materials. This work studied the action of laccases from Bacillus subtilis and Salmonella typhimurium (EC 1.10.3.2) on ground wood samples from yellow birch (Betula alleghaniensis) and red spruce (Picea rubens). The ability of bacterial laccases to modify wood can be facilitated by small molecule mediators. Herein, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), gallic acid and sinapic acid mediators were tested. Direct analysis of the wood samples was achieved by time-of-flight secondary ion mass spectrometry (ToF-SIMS), a surface sensitive mass spectrometry technique that has characteristic peaks for H, G and S lignin. The action of the bacterial laccases on both wood samples was demonstrated and revealed a strong mediator influence. The ABTS mediator led to delignification, evident in an overall increase of polysaccharide peaks in the residual solid, along with equal loss of G and S-lignin peaks. The gallic acid mediator demonstrated minimal laccase activity. Meanwhile, the sinapic acid mediator altered the S/G peak ratio consistent with mediator attaching to the wood solids. The current investigation demonstrates the action of bacterial laccase-mediator systems directly on woody materials, and the potential of using ToF-SIMS to uncover the fundamental and applied role of bacterial enzymes in lignocellulose conversion. © 2017 Scandinavian Plant Physiology Society.

Spontaneous and LH-induced maturation in Bufo arenarum oocytes: importance of gap junctions.

PubMed

Toranzo, G Sánchez; Oterino, J; Zelarayán, L; Bonilla, F; Bühler, M I

2007-02-01

It has been demonstrated in Bufo arenarum that fully grown oocytes are capable of meiotic resumption in the absence of a hormonal stimulus if they are deprived of their follicular envelopes. This event, called spontaneous maturation, only takes place in oocytes collected during the reproductive period, which have a metabolically mature cytoplasm. In Bufo arenarum, progesterone acts on the oocyte surface and causes modifications in the activities of important enzymes, such as a decrease in the activity of adenylate cyclase (AC) and the activation of phospholipase C (PLC). PLC activation leads to the formation of diacylglycerol (DAG) and inositol triphosphate (IP(3)), second messengers that activate protein kinase C (PKC) and cause an increase in intracellular Ca(2+). Recent data obtained from Bufo arenarum show that progesterone-induced maturation causes significant modifications in the level and composition of neutral lipids and phospholipids of whole fully grown ovarian oocytes and of enriched fractions in the plasma membrane. In amphibians, the luteinizing hormone (LH) is responsible for meiosis resumption through the induction of progesterone production by follicular cells. The aim of this work was to study the importance of gap junctions in the spontaneous and LH-induced maturation in Bufo arenarum oocytes. During the reproductive period, Bufo arenarum oocytes are capable of undergoing spontaneous maturation in a similar way to mammalian oocytes while, during the non-reproductive period, they exhibit the behaviour that is characteristic of amphibian oocytes, requiring progesterone stimulation for meiotic resumption (incapable oocytes). This different ability to mature spontaneously is coincident with differences in the amount and composition of the phospholipids in the oocyte membranes. Capable oocytes exhibit in their membranes higher quantities of phospholipids than incapable oocytes, especially of PC and PI, which are precursors of second messengers such as

Energy transfer in light-adapted photosynthetic membranes: from active to saturated photosynthesis.

PubMed

Fassioli, Francesca; Olaya-Castro, Alexandra; Scheuring, Simon; Sturgis, James N; Johnson, Neil F

2009-11-04

In bacterial photosynthesis light-harvesting complexes, LH2 and LH1 absorb sunlight energy and deliver it to reaction centers (RCs) with extraordinarily high efficiency. Submolecular resolution images have revealed that both the LH2:LH1 ratio, and the architecture of the photosynthetic membrane itself, adapt to light intensity. We investigate the functional implications of structural adaptations in the energy transfer performance in natural in vivo low- and high-light-adapted membrane architectures of Rhodospirillum photometricum. A model is presented to describe excitation migration across the full range of light intensities that cover states from active photosynthesis, where all RCs are available for charge separation, to saturated photosynthesis where all RCs are unavailable. Our study outlines three key findings. First, there is a critical light-energy density, below which the low-light adapted membrane is more efficient at absorbing photons and generating a charge separation at RCs, than the high-light-adapted membrane. Second, connectivity of core complexes is similar in both membranes, suggesting that, despite different growth conditions, a preferred transfer pathway is through core-core contacts. Third, there may be minimal subareas on the membrane which, containing the same LH2:LH1 ratio, behave as minimal functional units as far as excitation transfer efficiency is concerned.

Quantitative proteomic analysis of bacterial enzymes released in cheese during ripening.

PubMed

Jardin, Julien; Mollé, Daniel; Piot, Michel; Lortal, Sylvie; Gagnaire, Valérie

2012-04-02

Due to increasingly available bacterial genomes in databases, proteomic tools have recently been used to screen proteins expressed by micro-organisms in food in order to better understand their metabolism in situ. While the main objective is the systematic identification of proteins, the next step will be to bridge the gap between identification and quantification of these proteins. For that purpose, a new mass spectrometry-based approach was applied, using isobaric tagging reagent for quantitative proteomic analysis (iTRAQ), which are amine specific and yield labelled peptides identical in mass. Experimental Swiss-type cheeses were manufactured from microfiltered milk using Streptococcus thermophilus ITG ST20 and Lactobacillus helveticus ITG LH1 as lactic acid starters. At three ripening times (7, 20 and 69 days), cheese aqueous phases were extracted and enriched in bacterial proteins by fractionation. Each sample, standardised in protein amount prior to proteomic analyses, was: i) analysed by 2D-electrophoresis for qualitative analysis and ii) submitted to trypsinolysis, and labelled with specific iTRAQ tag, one per ripening time. The three labelled samples were mixed together and analysed by nano-LC coupled on-line with ESI-QTOF mass spectrometer. Thirty proteins, both from bacterial or bovine origin, were identified and efficiently quantified. The free bacterial proteins detected were enzymes from the central carbon metabolism as well as stress proteins. Depending on the protein considered, the quantity of these proteins in the cheese aqueous extract increased from 2.5 to 20 fold in concentration from day 7 to day 69 of ripening. Copyright © 2012 Elsevier B.V. All rights reserved.

Lower-hybrid (LH) oscillitons evolved from ion-acoustic (IA)/ion-cyclotron (IC) solitary waves: effect of electron inertia

NASA Astrophysics Data System (ADS)

Ma, J. Z. G.; Hirose, A.

2010-05-01

Lower-hybrid (LH) oscillitons reveal one aspect of geocomplexities. They have been observed by rockets and satellites in various regions in geospace. They are extraordinary solitary waves the envelop of which has a relatively longer period, while the amplitude is modulated violently by embedded oscillations of much shorter periods. We employ a two-fluid (electron-ion) slab model in a Cartesian geometry to expose the excitation of LH oscillitons. Relying on a set of self-similar equations, we first produce, as a reference, the well-known three shapes (sinusoidal, sawtooth, and spiky or bipolar) of parallel-propagating ion-acoustic (IA) solitary structures in the absence of electron inertia, along with their Fast Fourier Transform (FFT) power spectra. The study is then expanded to illustrate distorted structures of the IA modes by taking into account all the three components of variables. In this case, the ion-cyclotron (IC) mode comes into play. Furthermore, the electron inertia is incorporated in the equations. It is found that the inertia modulates the coupled IA/IC envelops to produce LH oscillitons. The newly excited structures are characterized by a normal low-frequency IC solitary envelop embedded by high-frequency, small-amplitude LH oscillations which are superimposed upon by higher-frequency but smaller-amplitude IA ingredients. The oscillitons are shown to be sensitive to several input parameters (e.g., the Mach number, the electron-ion mass/temperature ratios, and the electron thermal speed). Interestingly, whenever a LH oscilliton is triggered, there occurs a density cavity the depth of which can reach up to 20% of the background density, along with density humps on both sides of the cavity. Unexpectedly, a mode at much lower frequencies is also found beyond the IC band. Future studies are finally highlighted. The appendices give a general dispersion relation and specific ones of linear modes relevant to all the nonlinear modes encountered in the text.

Endophytic bacterial community of grapevine leaves influenced by sampling date and phytoplasma infection process

PubMed Central

2014-01-01

Background Endophytic bacteria benefit host plant directly or indirectly, e.g. by biocontrol of the pathogens. Up to now, their interactions with the host and with other microorganisms are poorly understood. Consequently, a crucial step for improving the knowledge of those relationships is to determine if pathogens or plant growing season influence endophytic bacterial diversity and dynamic. Results Four healthy, four phytoplasma diseased and four recovered (symptomatic plants that spontaneously regain a healthy condition) grapevine plants were sampled monthly from June to October 2010 in a vineyard in north-western Italy. Metagenomic DNA was extracted from sterilized leaves and the endophytic bacterial community dynamic and diversity were analyzed by taxon specific real-time PCR, Length-Heterogeneity PCR and genus-specific PCR. These analyses revealed that both sampling date and phytoplasma infection influenced the endophytic bacterial composition. Interestingly, in June, when the plants are symptomless and the pathogen is undetectable (i) the endophytic bacterial community associated with diseased grapevines was different from those in the other sampling dates, when the phytoplasmas are detectable inside samples; (ii) the microbial community associated with recovered plants differs from that living inside healthy and diseased plants. Interestingly, LH-PCR database identified bacteria previously reported as biocontrol agents in the examined grapevines. Of these, Burkholderia, Methylobacterium and Pantoea dynamic was influenced by the phytoplasma infection process and seasonality. Conclusion Results indicated that endophytic bacterial community composition in grapevine is correlated to both phytoplasma infection and sampling date. For the first time, data underlined that, in diseased plants, the pathogen infection process can decrease the impact of seasonality on community dynamic. Moreover, based on experimental evidences, it was reasonable to hypothesize that

Endophytic bacterial community of grapevine leaves influenced by sampling date and phytoplasma infection process.

PubMed

Bulgari, Daniela; Casati, Paola; Quaglino, Fabio; Bianco, Piero A

2014-07-21

Endophytic bacteria benefit host plant directly or indirectly, e.g. by biocontrol of the pathogens. Up to now, their interactions with the host and with other microorganisms are poorly understood. Consequently, a crucial step for improving the knowledge of those relationships is to determine if pathogens or plant growing season influence endophytic bacterial diversity and dynamic. Four healthy, four phytoplasma diseased and four recovered (symptomatic plants that spontaneously regain a healthy condition) grapevine plants were sampled monthly from June to October 2010 in a vineyard in north-western Italy. Metagenomic DNA was extracted from sterilized leaves and the endophytic bacterial community dynamic and diversity were analyzed by taxon specific real-time PCR, Length-Heterogeneity PCR and genus-specific PCR. These analyses revealed that both sampling date and phytoplasma infection influenced the endophytic bacterial composition. Interestingly, in June, when the plants are symptomless and the pathogen is undetectable (i) the endophytic bacterial community associated with diseased grapevines was different from those in the other sampling dates, when the phytoplasmas are detectable inside samples; (ii) the microbial community associated with recovered plants differs from that living inside healthy and diseased plants. Interestingly, LH-PCR database identified bacteria previously reported as biocontrol agents in the examined grapevines. Of these, Burkholderia, Methylobacterium and Pantoea dynamic was influenced by the phytoplasma infection process and seasonality. Results indicated that endophytic bacterial community composition in grapevine is correlated to both phytoplasma infection and sampling date. For the first time, data underlined that, in diseased plants, the pathogen infection process can decrease the impact of seasonality on community dynamic. Moreover, based on experimental evidences, it was reasonable to hypothesize that after recovery the restructured

Persistent organic pollutants as predictors of increased FSH:LH ratio in naturally cycling, reproductive age women.

PubMed

Gallo, Mia V; Ravenscroft, Julia; Carpenter, David O; Schell, Lawrence M; Akwesasne Task Force On The Environment

2018-07-01

Although several recent studies suggest endocrine disrupting compounds, such as polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p', DDE), and hexachlorobenzene (HCB), target different organs and systems in the body, their impact on female reproductive function in humans is not well characterized. We seek to determine the relationship between several known endocrine disrupting compounds and a marker of ovarian responsivity, the FSH:LH ratio (higher ratio indicates less ovarian responsivity). For this analysis, 169 naturally cycling women between 21 and 38 years of age completed interviews and had their blood drawn on day 3 of their menstrual cycle for analyses of toxicants, gonadal sex hormones (E 2 and P 4 ), and gonadotropins (FSH and LH). PCB congeners were classified into five groups based on their environmental persistence, distribution in human tissue, and toxicological action, reflecting the structure, mechanism, and known biological activity of individual PCB congeners. For every unit (ppb) increase in the level of the estrogenic PCB group, there was a 5-fold greater risk of a FSH:LH ratio ≥ 2, controlling for individual differences in age, percent body fat, cycle day 3 estradiol levels, parity, alcohol use and cigarette smoking in the past year (exp[ß] = 5; p = ≤0.01). PCB congeners identified as estrogenic were analyzed individually, and, of the 19 potentially estrogenic congeners, five were significantly, and positively related to an increased FSH:LH ratio. Four of these congeners are non-persistent, easily volatilize in the environment, and are easily metabolized, and hence, are indicative of very recent or current exposure. p,p'-DDE and HCB were not associated with FSH:LH ratio. We find a clinical indicator of ovarian responsivity, FSH:LH ratio, is associated with a specific group of estrogenic PCBs. These congeners may become airborne when they volatilize from dredged PCB-contaminated soil or from indoor PCB

Atomic force microscopy reveals multiple patterns of antenna organization in purple bacteria: implications for energy transduction mechanisms and membrane modeling.

PubMed

Sturgis, James N; Niederman, Robert A

2008-01-01

Recent topographs of the intracytoplasmic membrane (ICM) of purple bacteria obtained by atomic force microscopy (AFM) have provided the first surface views of the native architecture of a multicomponent biological membrane at submolecular resolution, representing an important landmark in structural biology. A variety of species-dependent, closely packed arrangements of light-harvesting (LH) complexes was revealed: the most highly organized was found in Rhodobacter sphaeroides in which the peripheral LH2 antenna was seen either in large clusters or in fixed rows interspersed among ordered arrays of dimeric LH1-reaction center (RC) core complexes. A more random organization was observed in other species containing both the LH1 and LH2 complexes, as typified by Rhododspirillum photometricum with randomly packed monomeric LH1-RC core complexes intermingled with large, paracrystalline domains of LH2 antenna. Surprisingly, no structures that could be identified as the ATP synthase or cytochrome bc (1) complexes were observed, which may reflect their localization at ICM vesicle poles or in curved membrane areas, out of view from the flat regions imaged by AFM. This possible arrangement of energy transducing complexes has required a reassessment of energy tranduction mechanisms which place the cytochrome bc (1) complex in close association with the RC. Instead, more plausible proposals must account for the movement of quinone redox species over considerable membrane distances on appropriate time scales. AFM, together with atomic resolution structures are also providing the basis for molecular modeling of the ICM that is leading to an improved picture of the supramolecular organization of photosynthetic complexes, as well as the forces that drive their segregation into distinct domains.

Cetrorelix suppresses the preovulatory LH surge and ovulation induced by ovulation-inducing factor (OIF) present in llama seminal plasma.

PubMed

Silva, Mauricio E; Smulders, Juan P; Guerra, Monserrat; Valderrama, Ximena P; Letelier, Claudia; Adams, Gregg P; Ratto, Marcelo H

2011-05-30

The purpose of the study was to determine if the effect of llama OIF on LH secretion is mediated by stimulation of the hypothalamus or pituitary gland. Using a 2-by-2 factorial design to examine the effects of OIF vs GnRH with or without a GnRH antagonist, llamas with a growing ovarian follicle greater than or equal to 8 mm were assigned randomly to four groups (n = 7 per group) and a) pre-treated with 1.5 mg of GnRH antagonist (cetrorelix acetate) followed by 1 mg of purified llama OIF, b) pre-treated with 1.5 mg of cetrorelix followed by 50 micrograms of GnRH, c) pre-treated with a placebo (2 ml of saline) followed by 1 mg of purified llama OIF or d) pre-treated with a placebo (2 ml of saline) followed by 50 micrograms of GnRH. Pre-treatment with cetrorelix or saline was given as a single slow intravenous dose 2 hours before intramuscular administration of either GnRH or OIF. Blood samples for LH measurement were taken every 15 minutes from 1.5 hours before to 8 hours after treatment. The ovaries were examined by ultrasonography to detect ovulation and CL formation. Blood samples for progesterone measurement were taken every-other-day from Day 0 (day of treatment) to Day 16. Ovulation rate was not different (P = 0.89) between placebo+GnRH (86%) and placebo+OIF groups (100%); however, no ovulations were detected in llamas pre-treated with cetrorelix. Plasma LH concentrations surged (P < 0.01) after treatment in both placebo+OIF and placebo+GnRH groups, but not in the cetrorelix groups. Maximum plasma LH concentrations and CL diameter profiles did not differ between the placebo-treated groups, but plasma progesterone concentrations were higher (P < 0.05), on days 6, 8 and 12 after treatment, in the OIF- vs GnRH-treated group. Cetrorelix (GnRH antagonist) inhibited the preovulatory LH surge induced by OIF in llamas suggesting that LH secretion is modulated by a direct or indirect effect of OIF on GnRH neurons in the hypothalamus.

Cortisol Secretory Parameters in Young Exercisers in Relation to LH Secretion and Bone Parameters

PubMed Central

Ackerman, Kathryn E.; Patel, Kamal T.; Guereca, Gabriela; Pierce, Lisa; Herzog, David B.; Misra, Madhusmita

2012-01-01

Objective Amenorrhoea and low bone density are common in excessive exercisers, yet endocrine factors that differentiate adolescent amenorrhoeic exercisers (AE) from eumenorrhoeic exercisers (EE) are unclear. We have previously reported that high ghrelin and low leptin predict lower LH secretion in AE. Leptin and ghrelin impact cortisol secretion, and hypercortisolaemia can inhibit LH pulsatility. We hypothesized that higher cortisol secretion in young endurance weight-bearing AE compared with EE and non-exercisers predicts lower LH secretion, lower levels of a bone formation marker and higher levels of a bone resorption marker. Design Cross-sectional Subjects We studied 21 AE, 18 EE and 20 non-exercisers 14–21 years (BMI 10th–90th%iles). Measurements Subjects underwent frequent sampling (11 p.m. to 7 a.m.) to assess cortisol, ghrelin, leptin and LH secretory dynamics. Fasting levels of a bone formation (P1NP) and bone resorption (CTX) marker were measured. Results BMI did not differ among groups. Cortisol pulse amplitude, mass, half-life and area under the curve (AUC) were highest in AE (p=0.04, 0.007, 0.04 and 0.003) and were associated inversely with fat mass (r=−0.29, −0.28 and −0.35, p=0.03, 0.04 and 0.007). We observed inverse associations between cortisol and LH AUC (r= −0.36, p=0.008), which persisted after controlling for fat mass, leptin and ghrelin AUC. Cortisol correlated positively with CTX in EE and inversely with P1NP in non-exercisers. Conclusions Higher cortisol secretion in AE compared with EE and non-exercisers is associated with lower LH secretion. Effects of leptin and ghrelin on LH secretion may be mediated by increased cortisol. PMID:22671919

Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses

DOE PAGES

Schostag, Morten; Stibal, Marek; Jacobsen, Carsten S.; ...

2015-04-30

The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78°N) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable organic matter on the bacterial communities. The copy numbermore » of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below -10°C. Multivariate statistical analysis of the bacterial diversity data (DNA and cDNA libraries) revealed a season-based clustering of the samples, and, e.g., the relative abundance of potentially active Cyanobacteria peaked in June and Alphaproteobacteria increased over the summer and then declined from October to November. The structure of the bulk (DNA-based) community was significantly correlated with pH and dissolved organic carbon, while the potentially active (RNA-based) community structure was not significantly correlated with any of the measured soil parameters. A large fraction of the 16S rRNA transcripts was assigned to nitrogen-fixing bacteria (up to 24% in June) and phototrophic organisms (up to 48% in June) illustrating the potential importance of nitrogen fixation in otherwise nitrogen poor Arctic ecosystems and of phototrophic bacterial activity on the soil surface.« less

Distinct summer and winter bacterial communities in the active layer of Svalbard permafrost revealed by DNA- and RNA-based analyses

PubMed Central

Schostag, Morten; Stibal, Marek; Jacobsen, Carsten S.; Bælum, Jacob; Taş, Neslihan; Elberling, Bo; Jansson, Janet K.; Semenchuk, Philipp; Priemé, Anders

2015-01-01

The active layer of soil overlaying permafrost in the Arctic is subjected to dramatic annual changes in temperature and soil chemistry, which likely affect bacterial activity and community structure. We studied seasonal variations in the bacterial community of active layer soil from Svalbard (78°N) by co-extracting DNA and RNA from 12 soil cores collected monthly over a year. PCR amplicons of 16S rRNA genes (DNA) and reverse transcribed transcripts (cDNA) were quantified and sequenced to test for the effect of low winter temperature and seasonal variation in concentration of easily degradable organic matter on the bacterial communities. The copy number of 16S rRNA genes and transcripts revealed no distinct seasonal changes indicating potential bacterial activity during winter despite soil temperatures well below −10°C. Multivariate statistical analysis of the bacterial diversity data (DNA and cDNA libraries) revealed a season-based clustering of the samples, and, e.g., the relative abundance of potentially active Cyanobacteria peaked in June and Alphaproteobacteria increased over the summer and then declined from October to November. The structure of the bulk (DNA-based) community was significantly correlated with pH and dissolved organic carbon, while the potentially active (RNA-based) community structure was not significantly correlated with any of the measured soil parameters. A large fraction of the 16S rRNA transcripts was assigned to nitrogen-fixing bacteria (up to 24% in June) and phototrophic organisms (up to 48% in June) illustrating the potential importance of nitrogen fixation in otherwise nitrogen poor Arctic ecosystems and of phototrophic bacterial activity on the soil surface. PMID:25983731

Structure and Orientation of Bovine Lactoferrampin in the Mimetic Bacterial Membrane as Revealed by Solid-State NMR and Molecular Dynamics Simulation

PubMed Central

Tsutsumi, Atsushi; Javkhlantugs, Namsrai; Kira, Atsushi; Umeyama, Masako; Kawamura, Izuru; Nishimura, Katsuyuki; Ueda, Kazuyoshi; Naito, Akira

2012-01-01

Bovine lactoferrampin (LFampinB) is a newly discovered antimicrobial peptide found in the N1-domain of bovine lactoferrin (268–284), and consists of 17 amino-acid residues. It is important to determine the orientation and structure of LFampinB in bacterial membranes to reveal the antimicrobial mechanism. We therefore performed 13C and 31P NMR, 13C-31P rotational echo double resonance (REDOR), potassium ion-selective electrode, and quartz-crystal microbalance measurements for LFampinB with mimetic bacterial membrane and molecular-dynamics simulation in acidic membrane. 31P NMR results indicated that LFampinB caused a defect in mimetic bacterial membranes. Ion-selective electrode measurements showed that ion leakage occurred for the mimetic bacterial membrane containing cardiolipin. Quartz-crystal microbalance measurements revealed that LFampinB had greater affinity to acidic phospholipids than that to neutral phospholipids. 13C DD-MAS and static NMR spectra showed that LFampinB formed an α-helix in the N-terminus region and tilted 45° to the bilayer normal. REDOR dephasing patterns between carbonyl carbon nucleus in LFampinB and phosphorus nuclei in lipid phosphate groups were measured by 13C-31P REDOR and the results revealed that LFampinB is located in the interfacial region of the membrane. Molecular-dynamics simulation showed the tilt angle to be 42° and the rotation angle to be 92.5° for Leu3, which are in excellent agreement with the experimental values. PMID:23083717

Coupled cryoconite ecosystem structure-function relationships are revealed by comparing bacterial communities in alpine and Arctic glaciers.

PubMed

Edwards, Arwyn; Mur, Luis A J; Girdwood, Susan E; Anesio, Alexandre M; Stibal, Marek; Rassner, Sara M E; Hell, Katherina; Pachebat, Justin A; Post, Barbara; Bussell, Jennifer S; Cameron, Simon J S; Griffith, Gareth Wyn; Hodson, Andrew J; Sattler, Birgit

2014-08-01

Cryoconite holes are known as foci of microbial diversity and activity on polar glacier surfaces, but are virtually unexplored microbial habitats in alpine regions. In addition, whether cryoconite community structure reflects ecosystem functionality is poorly understood. Terminal restriction fragment length polymorphism and Fourier transform infrared metabolite fingerprinting of cryoconite from glaciers in Austria, Greenland and Svalbard demonstrated cryoconite bacterial communities are closely correlated with cognate metabolite fingerprints. The influence of bacterial-associated fatty acids and polysaccharides was inferred, underlining the importance of bacterial community structure in the properties of cryoconite. Thus, combined application of T-RFLP and FT-IR metabolite fingerprinting promises high throughput, and hence, rapid assessment of community structure-function relationships. Pyrosequencing revealed Proteobacteria were particularly abundant, with Cyanobacteria likely acting as ecosystem engineers in both alpine and Arctic cryoconite communities. However, despite these generalities, significant differences in bacterial community structures, compositions and metabolomes are found between alpine and Arctic cryoconite habitats, reflecting the impact of local and regional conditions on the challenges of thriving in glacial ecosystems. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Shrimp alpha-2-macroglobulin prevents the bacterial escape by inhibiting fibrinolysis of blood clots.

PubMed

Chaikeeratisak, Vorrapon; Somboonwiwat, Kunlaya; Tassanakajon, Anchalee

2012-01-01

Proteomic analysis of the hemocytic proteins of Penaeus monodon (Pm) has previously shown that alpha-2-macroglobulin (A2M) was among the proteins that showed substantially altered expression levels upon Vibrio harveyi infection. Therefore, in this study its potentially important role in the response of shrimp to bacterial infection was further characterized. The yeast two-hybrid system revealed that the receptor binding domain of PmA2M interacted with the carboxyl-terminus of one or both of the transglutaminase type II isoforms, which are key enzymes involved in the shrimp clotting system. In accord with this, PmA2M was found to be localized on the extracellular blood clots and to colocalize with clottable proteins. RNA interference (RNAi)-mediated knockdown of A2M transcript levels reduced the PmA2M transcript levels (∼94%) and significantly reduced the bacterial seizing ability of the clotting system, resulting in an up to 3.3-fold higher number of V. harveyi that systemically disseminated into the circulatory system at 5 min post-infection before subsequent clearance by the immune system. Furthermore, an appearance of PmA2M depleted clots in the presence of V. harveyi strikingly demonstrated fibrinolysis zones surrounding the bacteria. This study provides the first evidence of the vital role of PmA2M in enhancing bacterial sequestration by protecting blood clots against fibrinolysis.

Enantiomeric characterization and structure elucidation of LH601A using vibrational circular dichroism spectroscopy

NASA Astrophysics Data System (ADS)

Shen, Jian; Magesh, Sadagopan; Chen, Lin; Hu, Longqin; He, Yanan

2018-03-01

LH601A is a novel non-reactive chiral molecule inhibiting Keap1-Nrf2 protein-protein interaction. The absolute configuration (AC) was independently determined in this study using vibrational circular dichroism (VCD) spectroscopy. Because of band overlapping and broadening in the IR spectrum, a direct VCD spectrum comparison method is devised without the conventional IR band alignment. Being an unbiased AC inquiry, all possible chiralities are evaluated based on the statistical analysis of VCD similarity, Sv. The AC of three-center stereoisomer LH601A is unambiguously assigned to (S,R,S). A comparative study was also carried out to investigate the structural and energy differences of calculated conformers using the polarized continuum model of dimethyl sulfoxide.

Crystal structure analysis reveals Pseudomonas PilY1 as an essential calcium-dependent regulator of bacterial surface motility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orans, Jillian; Johnson, Michael D.L.; Coggan, Kimberly A.

Several bacterial pathogens require the 'twitching' motility produced by filamentous type IV pili (T4P) to establish and maintain human infections. Two cytoplasmic ATPases function as an oscillatory motor that powers twitching motility via cycles of pilus extension and retraction. The regulation of this motor, however, has remained a mystery. We present the 2.1 {angstrom} resolution crystal structure of the Pseudomonas aeruginosa pilus-biogenesis factor PilY1, and identify a single site on this protein required for bacterial translocation. The structure reveals a modified {beta}-propeller fold and a distinct EF-hand-like calcium-binding site conserved in pathogens with retractile T4P. We show that preventing calciummore » binding by PilY1 using either an exogenous calcium chelator or mutation of a single residue disrupts Pseudomonas twitching motility by eliminating surface pili. In contrast, placing a lysine in this site to mimic the charge of a bound calcium interferes with motility in the opposite manner - by producing an abundance of nonfunctional surface pili. Our data indicate that calcium binding and release by the unique loop identified in the PilY1 crystal structure controls the opposing forces of pilus extension and retraction. Thus, PilY1 is an essential, calcium-dependent regulator of bacterial twitching motility.« less

Spatial and species variations in bacterial communities associated with corals from the Red Sea as revealed by pyrosequencing.

PubMed

Lee, On On; Yang, Jiangke; Bougouffa, Salim; Wang, Yong; Batang, Zenon; Tian, Renmao; Al-Suwailem, Abdulaziz; Qian, Pei-Yuan

2012-10-01

Microbial associations with corals are common and are most likely symbiotic, although their diversity and relationships with environmental factors and host species remain unclear. In this study, we adopted a 16S rRNA gene tag-pyrosequencing technique to investigate the bacterial communities associated with three stony Scleractinea and two soft Octocorallia corals from three locations in the Red Sea. Our results revealed highly diverse bacterial communities in the Red Sea corals, with more than 600 ribotypes detected and up to 1,000 species estimated from a single coral species. Altogether, 21 bacterial phyla were recovered from the corals, of which Gammaproteobacteria was the most dominant group, and Chloroflexi, Chlamydiae, and the candidate phylum WS3 were reported in corals for the first time. The associated bacterial communities varied greatly with location, where environmental conditions differed significantly. Corals from disturbed areas appeared to share more similar bacterial communities, but larger variations in community structures were observed between different coral species from pristine waters. Ordination methods identified salinity and depth as the most influential parameters affecting the abundance of Vibrio, Pseudoalteromonas, Serratia, Stenotrophomonas, Pseudomonas, and Achromobacter in the corals. On the other hand, bacteria such as Chloracidobacterium and Endozoicomonas were more sensitive to the coral species, suggesting that the host species type may be influential in the associated bacterial community, as well. The combined influences of the coral host and environmental factors on the associated microbial communities are discussed. This study represents the first comparative study using tag-pyrosequencing technology to investigate the bacterial communities in Red Sea corals.

Spatial and Species Variations in Bacterial Communities Associated with Corals from the Red Sea as Revealed by Pyrosequencing

PubMed Central

Lee, On On; Yang, Jiangke; Bougouffa, Salim; Wang, Yong; Batang, Zenon; Tian, Renmao; Al-Suwailem, Abdulaziz

2012-01-01

Microbial associations with corals are common and are most likely symbiotic, although their diversity and relationships with environmental factors and host species remain unclear. In this study, we adopted a 16S rRNA gene tag-pyrosequencing technique to investigate the bacterial communities associated with three stony Scleractinea and two soft Octocorallia corals from three locations in the Red Sea. Our results revealed highly diverse bacterial communities in the Red Sea corals, with more than 600 ribotypes detected and up to 1,000 species estimated from a single coral species. Altogether, 21 bacterial phyla were recovered from the corals, of which Gammaproteobacteria was the most dominant group, and Chloroflexi, Chlamydiae, and the candidate phylum WS3 were reported in corals for the first time. The associated bacterial communities varied greatly with location, where environmental conditions differed significantly. Corals from disturbed areas appeared to share more similar bacterial communities, but larger variations in community structures were observed between different coral species from pristine waters. Ordination methods identified salinity and depth as the most influential parameters affecting the abundance of Vibrio, Pseudoalteromonas, Serratia, Stenotrophomonas, Pseudomonas, and Achromobacter in the corals. On the other hand, bacteria such as Chloracidobacterium and Endozoicomonas were more sensitive to the coral species, suggesting that the host species type may be influential in the associated bacterial community, as well. The combined influences of the coral host and environmental factors on the associated microbial communities are discussed. This study represents the first comparative study using tag-pyrosequencing technology to investigate the bacterial communities in Red Sea corals. PMID:22865078

Influence of sodium valproate on medium-late luteal phase pulsatile LH secretion in normal women.

PubMed

Lado Abeal, J; Rey Losada, C; Cabezas Agricola, J M; Cabezas-Cerrato, J

1994-01-01

It is not known whether gamma-aminobutyric acid (GABA) is involved in control of pulsatile LH secretion in human beings. Previous work by our group has shown that manipulation of the GABAergic system with sodium valproate does not affect pulsatile LH secretion in normal women in the late follicular phase. However, it has been suggested that steroid levels are critical for the influence of GABA upon hormone secretion; in particular, progesterone has been said to enhance inhibition by GABA. In this work we studied the effect of sodium valproate on pulsatile LH secretion in medium-late luteal phase of normal women. Six normal young women were studied over an 8-hour period in two successive menstrual cycles. On each occasion blood samples were taken every 10 minutes between 1000 and 1800 h. We administered 400 mg of sodium valproate every 8 hours on the 7 days preceding their second cycle and additional 400 mg at 0900 and 1400 h on the day of the study. Ovulation day was estimated by means of serial ovarian ultrasound examinations and confirmed by serum progesterone concentrations. In each cycle, LH, oestradiol and progesterone were determined by radioimmunoassay and sodium valproate by repolarization fluorescence spectrophotometry. The series of LH levels was smoothed for 1-minute sampling periods by means of a spline function and analysed by means of a program developed in our laboratory and written in Fortran 77. The program deconvolved the signal and calculated the pulse area, pulse duration, interpulse interval and number of pulses. LH pulse identification on the deconvolved signals was performed using our own method based on Friedman's non-parametric statistic. The statistical significance of differences between parameters was estimated using the Mann-Whitney test and Wilcoxon signed rank test. There were no significant differences in LH pulse area, pulse duration, interpulse interval or number of pulses with the administration of sodium valproate. Activation of

Genomic analysis reveals the major driving forces of bacterial life in the rhizosphere

PubMed Central

Matilla, Miguel A; Espinosa-Urgel, Manuel; Rodríguez-Herva, José J; Ramos, Juan L; Ramos-González, María Isabel

2007-01-01

Background Mutualistic interactions less well known than those between rhizobia and legumes are commonly found between plants and bacteria, frequently pseudomonads, which colonize roots and adjacent soil areas (the rhizosphere). Results A global analysis of Pseudomonas putida genes expressed during their interaction with maize roots revealed how a bacterial population adjusts its genetic program to this lifestyle. Differentially expressed genes were identified by comparing rhizosphere-colonizing populations with three distinct controls covering a variety of nutrients, growth phases and life styles (planktonic and sessile). Ninety rhizosphere up-regulated (rup) genes, which were induced relative to all three controls, were identified, whereas there was no repressed gene in common between the experiments. Genes involved in amino acid uptake and metabolism of aromatic compounds were preferentially expressed in the rhizosphere, which reflects the availability of particular nutrients in root exudates. The induction of efflux pumps and enzymes for glutathione metabolism indicates that adaptation to adverse conditions and stress (oxidative) response are crucial for bacterial life in this environment. The finding of a GGDEF/EAL domain response regulator among the induced genes suggests a role for the turnover of the secondary messenger c-diGMP in root colonization. Several mutants in rup genes showed reduced fitness in competitive root colonization. Conclusion Our results show the importance of two selective forces of different nature to colonize the rhizosphere: stress adaptation and availability of particular nutrients. We also identify new traits conferring bacterial survival in this niche and open a way to the characterization of specific signalling and regulatory processes governing the plant-Pseudomonas association. PMID:17784941

Differential testosterone response to GnRH-induced LH release before and after musth in adult Asian elephant (Elephas maximus) bulls.

PubMed

Somgird, Chaleamchat; Sripiboon, Supaphen; Mahasawangkul, Sittidet; Boonprasert, Khajohnpat; Brown, Janine L; Stout, Tom A E; Colenbrander, Ben; Thitaram, Chatchote

2016-04-15

Bull elephants exhibit marked increases in testosterone secretion during musth, and studies have shown a heightened sensitivity of the testis to GnRH-stimulated testosterone production in musth compared to nonmusth males. However, activity of the hypothalamo-pituitary-gonadal axis before or soon after musth has not been studied in detail. The aim of this study was to evaluate LH and testosterone responses to GnRH challenge in nine adult Asian elephant (Elephas maximus) bulls during three periods relative to musth: premusth, postmusth, and nonmusth. Bulls were administered 80 μg of a GnRH agonist, and blood was collected before and after injection to monitor serum hormone concentrations. The same bulls were injected with saline 2 weeks before each GnRH challenge and monitored using the same blood collection protocol. All bulls responded to GnRH, but not saline, with an increase in LH and testosterone during all three periods. The mean peak LH (1.76 ± 0.19 ng/mL; P < 0.001) and testosterone (6.71 ± 1.62 ng/mL; P = 0.019) concentrations after GnRH were higher than the respective baselines (0.57 ± 0.07 ng/mL, 3.05 ± 0.60 ng/mL). Although basal- and GnRH-induced LH secretion were similar across the stages, evaluation of the area under the curve in GnRH-treated bulls indicated that the testosterone response was greatest during premusth (2.84 ± 0.76 area units; P = 0.019) compared to postmusth (2.02 ± 0.63 area units), and nonmusth (2.01 ± 0.46 area units). This confirms earlier reports that GnRH stimulates LH release and subsequent testosterone production in bull elephants. Furthermore, although the hypothalamo-pituitary-gonadal axis is active throughout the year, the testis appears to be more responsive to LH in terms of testosterone production in the period leading up to musth, compared to the nonmusth and postmusth periods. This heightened sensitivity, perhaps as a result of LH receptor up-regulation, may prime the testis for maximal

Male goat vocalizations stimulate the estrous behavior and LH secretion in anestrous goats that have been previously exposed to bucks.

PubMed

Delgadillo, José Alberto; Vielma, Jesús; Hernandez, Horacio; Flores, José Alfredo; Duarte, Gerardo; Fernández, Ilda Graciela; Keller, Matthieu; Gelez, Hélène

2012-09-01

We investigated whether live vocalizations emitted by bucks interacting with anestrous females stimulate secretion of LH, estrous behavior and ovulation in anestrous goats. In experiment 1, bucks rendered sexually active by exposure to long days followed by natural photoperiod were exposed in a light-proof-building to five anestrous females. Buck vocalizations were reproduced through a microphone-amplifier-loudspeaker system to an open pen where one group of goats (n=6) was exposed for 10 days to these live vocalizations. Another group of females (n=6) was isolated from males and vocalizations. The proportion of goats displaying estrous behavior was significantly higher in females exposed to buck vocalizations than in females isolated from males. The proportion of goats that ovulated did not differ between the 2 groups (exposed to males versus isolated). In experiment 2, female goats that either had previous contact with males (n=7), or no previous contact with males (n=7) were exposed to live buck vocalizations, reproduced as described in experiment 1, for 5 days. The number and amplitude of LH pulses did not differ between groups before exposition to buck vocalizations. Five days of exposure to male vocalizations significantly increased LH pulsatility only in females that had previous contact with males, while LH pulse amplitude was not modified. We concluded that live buck vocalizations can stimulate estrous behavior and LH secretion in goats if they have had previous contact with bucks. Copyright © 2012 Elsevier Inc. All rights reserved.

Diverse culturable bacterial communities with cellulolytic potential revealed from pristine habitat in Indian trans-Himalaya.

PubMed

Thakur, Vikas; Kumar, Vijay; Kumar, Sanjay; Singh, Dharam

2018-05-28

Pangi-Chamba Himalaya (PCH) region is very pristine, unique and virgin niche for bioresource exploration. In the current study, for the first time, the bacterial diversity of this region for potential cellulose degrader was investigated. A total of 454 pure bacterial isolates were obtained from diverse sites in PCH region and 111 isolates were further selected for 16S rDNA characterization based on ARDRA grouping. Identified bacteria belongs to twenty-eight genera representing four phyla namely Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes. Pseudomonas was most abundant genera followed by Bacillus, Geobacillus, Arthrobacter, Paenibacillus, and Flavobacterium. In addition, 6 putative novel bacteria (based on 16S rDNA sequence similarity) and thermophiles from non-thermogenic sites were also reported for the first time. Screening for cellulose degradation ability on carboxymethyl cellulose (CMC) plates had revealed 70.92% of cellulolytic bacteria. Current study reports diverse genera (Arthrobacter, Paenibacillus, Chryseobacterium, Pedobacter, Streptomyces, Agromyces, Flavobacterium, and Pseudomonas), high cellulose hydrolysis zone, and wide pH and temperature functional cellulolytic bacteria hitherto reported in the literature. Diverse bacterial genera with high cellulolytic activity in broad pH and temperature range provide opportunity to develop a bioprocess for efficient pretreatment of lignocellulosic biomass, which is currently being investigated.

An integrated metagenomics pipeline for strain profiling reveals novel patterns of bacterial transmission and biogeography

PubMed Central

Nayfach, Stephen; Rodriguez-Mueller, Beltran; Garud, Nandita

2016-01-01

We present the Metagenomic Intra-species Diversity Analysis System (MIDAS), which is an integrated computational pipeline for quantifying bacterial species abundance and strain-level genomic variation, including gene content and single-nucleotide polymorphisms (SNPs), from shotgun metagenomes. Our method leverages a database of more than 30,000 bacterial reference genomes that we clustered into species groups. These cover the majority of abundant species in the human microbiome but only a small proportion of microbes in other environments, including soil and seawater. We applied MIDAS to stool metagenomes from 98 Swedish mothers and their infants over one year and used rare SNPs to track strains between hosts. Using this approach, we found that although species compositions of mothers and infants converged over time, strain-level similarity diverged. Specifically, early colonizing bacteria were often transmitted from an infant’s mother, while late colonizing bacteria were often transmitted from other sources in the environment and were enriched for spore-formation genes. We also applied MIDAS to 198 globally distributed marine metagenomes and used gene content to show that many prevalent bacterial species have population structure that correlates with geographic location. Strain-level genetic variants present in metagenomes clearly reveal extensive structure and dynamics that are obscured when data are analyzed at a coarser taxonomic resolution. PMID:27803195

Production of specific antisera for radioimmunoassay of human luteinizing hormone (LH) in the presence of human chorionic gonadotropin (hCG). [/sup 125/I

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thorell, J.I.; Jeppsson, S.; Holmstrom, B.

1976-09-01

A specific radioimmunoassay for LH, which measures plasma LH in the presence of human chorionic gonadotropin (hCG) is described. Rabbits were immunized with highly purified native LH. One of the antisera with a difference in its reactivity against LH and hCG was further purified by affinity chromatography on a column with hCG coupled to Sepharose 4B. The adsorbed antiserum and /sup 125/I-LH was used in a double antibody assay. The LH standard (MRC/68/40) efficiently inhibited the binding of /sup 125/I-LH, and the standard curve showed a sensitivity of 0.5 ng/ml in the sample. hCG up to 10,000 ng/ml did notmore » inhibit the binding of /sup 125/I-LH. The plasma level of LH in pregnant women in the first trimester was low (1.3 +- 0.1 ng/ml). When LH was measured in fertile or menopausal women with or without stimulation with LH/FSH releasing hormone (LH-RH)/sup x/ the results agreed to those found with our conventional LH-assay based on antiserum against hCG.« less

Arginine-lysine positional swap of the LL-37 peptides reveals evolutional advantages of the native sequence and leads to bacterial probes.

PubMed

Wang, Xiuqing; Junior, José Carlos Bozelli; Mishra, Biswajit; Lushnikova, Tamara; Epand, Richard M; Wang, Guangshun

2017-08-01

Antimicrobial peptides are essential components of the innate immune system of multicellular organisms. Although cationic and hydrophobic amino acids are known determinants of these amphipathic molecules for bacterial killing, it is not clear how lysine-arginine (K-R) positional swaps influence peptide structure and activity. This study addresses this question by investigating two groups of peptides (GF-17 and 17BIPHE2) derived from human cathelicidin LL-37. K-R positional swap showed little effect on minimal inhibitory concentrations of the peptides. However, there are clear differences in bacterial killing kinetics. The membrane permeation patterns vary with peptide and bacterial types, but not changes in fluorescent dyes, salts or pH. In general, the original peptide is more efficient in bacterial killing, but less toxic to human cells, than the K-R swapped peptides, revealing the evolutionary significance of the native sequence for host defense. The characteristic membrane permeation patterns for different bacteria suggest a possible application of these K-R positional-swapped peptides as molecular probes for the type of bacteria. Such differences are related to bacterial membrane compositions: minimal for Gram-positive Staphylococcus aureus with essentially all anionic lipids (cardiolipin and phosphatidylglycerol), but evident for Gram-negative Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli with a mixture of phosphatidylethanolamine and phosphatidylglycerol. Biophysical characterization found similar structures and binding affinities for these peptides in vesicle systems mimicking E. coli and S. aureus. It seems that interfacial arginines of GF-17 are preferred over lysines in bacterial membrane permeation. Our study sheds new light on the design of cationic amphipathic peptides. Copyright © 2017 Elsevier B.V. All rights reserved.

Role of exogenous estrogen in initiation of estrus and induction of an LH surge

USDA-ARS?s Scientific Manuscript database

Among cattle the LH surge that causes ovulation occurs shortly after the onset of a spontaneous estrus. In addition an injection of 100 'g of GnRH can induce an LH surge capable of inducing ovulation. We hypothesized that different preovulatory estradiol profiles would result in different ovulator...

Shrimp Alpha-2-Macroglobulin Prevents the Bacterial Escape by Inhibiting Fibrinolysis of Blood Clots

PubMed Central

Chaikeeratisak, Vorrapon; Somboonwiwat, Kunlaya; Tassanakajon, Anchalee

2012-01-01

Proteomic analysis of the hemocytic proteins of Penaeus monodon (Pm) has previously shown that alpha-2-macroglobulin (A2M) was among the proteins that showed substantially altered expression levels upon Vibrio harveyi infection. Therefore, in this study its potentially important role in the response of shrimp to bacterial infection was further characterized. The yeast two-hybrid system revealed that the receptor binding domain of PmA2M interacted with the carboxyl-terminus of one or both of the transglutaminase type II isoforms, which are key enzymes involved in the shrimp clotting system. In accord with this, PmA2M was found to be localized on the extracellular blood clots and to colocalize with clottable proteins. RNA interference (RNAi)-mediated knockdown of A2M transcript levels reduced the PmA2M transcript levels (∼94%) and significantly reduced the bacterial seizing ability of the clotting system, resulting in an up to 3.3-fold higher number of V. harveyi that systemically disseminated into the circulatory system at 5 min post-infection before subsequent clearance by the immune system. Furthermore, an appearance of PmA2M depleted clots in the presence of V. harveyi strikingly demonstrated fibrinolysis zones surrounding the bacteria. This study provides the first evidence of the vital role of PmA2M in enhancing bacterial sequestration by protecting blood clots against fibrinolysis. PMID:23082160

Do Substance P and Neurokinin A Play Important Roles in the Control of LH Secretion in Ewes?

PubMed Central

Fergani, Chrysanthi; Mazzella, Leanne; Coolen, Lique M.; McCosh, Richard B.; Hardy, Steven L.; Newcomb, Nora; Grachev, Pasha; Lehman, Michael N.

2016-01-01

There is now general agreement that neurokinin B (NKB) acts via neurokinin-3-receptor (NK3R) to stimulate secretion of GnRH and LH in several species, including rats, mice, sheep, and humans. However, the roles of two other tachykinins, substance P (SP) and neurokinin A, which act primarily via NK1R and NK2R, respectively, are less clear. In rodents, these signaling pathways can stimulate LH release and substitute for NKB signaling; in humans, SP is colocalized with kisspeptin and NKB in the mediobasal hypothalamus. In this study, we examined the possible role of these tachykinins in control of the reproductive axis in sheep. Immunohistochemistry was used to describe the expression of SP and NK1R in the ovine diencephalon and determine whether these proteins are colocalized in kisspeptin or GnRH neurons. SP-containing cell bodies were largely confined to the arcuate nucleus, but NK1R-immunoreactivity was more widespread. However, there was very low coexpression of SP or NK1R in kisspeptin cells and none in GnRH neurons. We next determined the minimal effective dose of these three tachykinins that would stimulate LH secretion when administered into the third ventricle of ovary-intact anestrous sheep. A much lower dose of NKB (0.2 nmol) than of neurokinin A (2 nmol) or SP (10 nmol) consistently stimulated LH secretion. Moreover, the relative potency of these three neuropeptides parallels the relative selectivity of NK3R. Based on these anatomical and pharmacological data, we conclude that NKB-NK3R signaling is the primary pathway for the control of GnRH secretion by tachykinins in ewes. PMID:27704950

Do Substance P and Neurokinin A Play Important Roles in the Control of LH Secretion in Ewes?

PubMed

Fergani, Chrysanthi; Mazzella, Leanne; Coolen, Lique M; McCosh, Richard B; Hardy, Steven L; Newcomb, Nora; Grachev, Pasha; Lehman, Michael N; Goodman, Robert L

2016-12-01

There is now general agreement that neurokinin B (NKB) acts via neurokinin-3-receptor (NK3R) to stimulate secretion of GnRH and LH in several species, including rats, mice, sheep, and humans. However, the roles of two other tachykinins, substance P (SP) and neurokinin A, which act primarily via NK1R and NK2R, respectively, are less clear. In rodents, these signaling pathways can stimulate LH release and substitute for NKB signaling; in humans, SP is colocalized with kisspeptin and NKB in the mediobasal hypothalamus. In this study, we examined the possible role of these tachykinins in control of the reproductive axis in sheep. Immunohistochemistry was used to describe the expression of SP and NK1R in the ovine diencephalon and determine whether these proteins are colocalized in kisspeptin or GnRH neurons. SP-containing cell bodies were largely confined to the arcuate nucleus, but NK1R-immunoreactivity was more widespread. However, there was very low coexpression of SP or NK1R in kisspeptin cells and none in GnRH neurons. We next determined the minimal effective dose of these three tachykinins that would stimulate LH secretion when administered into the third ventricle of ovary-intact anestrous sheep. A much lower dose of NKB (0.2 nmol) than of neurokinin A (2 nmol) or SP (10 nmol) consistently stimulated LH secretion. Moreover, the relative potency of these three neuropeptides parallels the relative selectivity of NK3R. Based on these anatomical and pharmacological data, we conclude that NKB-NK3R signaling is the primary pathway for the control of GnRH secretion by tachykinins in ewes.

Analysis of LH Launcher Arrays (Like the ITER One) Using the TOPLHA Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maggiora, R.; Milanesio, D.; Vecchi, G.

2009-11-26

TOPLHA (Torino Polytechnic Lower Hybrid Antenna) code is an innovative tool for the 3D/1D simulation of Lower Hybrid (LH) antennas, i.e. accounting for realistic 3D waveguides geometry and for accurate 1D plasma models, and without restrictions on waveguide shape, including curvature. This tool provides a detailed performances prediction of any LH launcher, by computing the antenna scattering parameters, the current distribution, electric field maps and power spectra for any user-specified waveguide excitation. In addition, a fully parallelized and multi-cavity version of TOPLHA permits the analysis of large and complex waveguide arrays in a reasonable simulation time. A detailed analysis ofmore » the performances of the proposed ITER LH antenna geometry has been carried out, underlining the strong dependence of the antenna input parameters with respect to plasma conditions. A preliminary optimization of the antenna dimensions has also been accomplished. Electric current distribution on conductors, electric field distribution at the interface with plasma, and power spectra have been calculated as well. The analysis shows the strong capabilities of the TOPLHA code as a predictive tool and its usefulness to LH launcher arrays detailed design.« less

Developmental Programming: Prenatal and Postnatal Androgen Antagonist and Insulin Sensitizer Interventions Prevent Advancement of Puberty and Improve LH Surge Dynamics in Prenatal Testosterone-Treated Sheep

PubMed Central

Veiga-Lopez, Almudena; Herkimer, Carol; Abi Salloum, Bachir; Moeller, Jacob; Beckett, Evan; Sreedharan, Rohit

2015-01-01

Prenatal T excess induces maternal hyperinsulinemia, early puberty, and reproductive/metabolic defects in the female similar to those seen in women with polycystic ovary syndrome. This study addressed the organizational/activational role of androgens and insulin in programming pubertal advancement and periovulatory LH surge defects. Treatment groups included the following: 1) control; 2) prenatal T; 3) prenatal T plus prenatal androgen antagonist, flutamide; 4) prenatal T plus prenatal insulin sensitizer, rosiglitazone; 5) prenatal T and postnatal flutamide; 6) prenatal T and postnatal rosiglitazone; and 7) prenatal T and postnatal metformin. Prenatal treatments spanned 30–90 days of gestation and postnatal treatments began at approximately 8 weeks of age and continued throughout. Blood samples were taken twice weekly, beginning at approximately 12 weeks of age to time puberty. Two-hour samples after the synchronization with prostaglandin F2α were taken for 120 hours to characterize LH surge dynamics at 7 and 19 months of age. Prenatal T females entered puberty earlier than controls, and all interventions prevented this advancement. Prenatal T reduced the percentage of animals having LH surge, and females that presented LH surge exhibited delayed timing and dampened amplitude of the LH surge. Prenatal androgen antagonist, but not other interventions, restored LH surges without normalizing the timing of the surge. Normalization of pubertal timing with prenatal/postnatal androgen antagonist and insulin sensitizer interventions suggests that pubertal advancement is programmed by androgenic actions of T involving insulin as a mediary. Restoration of LH surges by cotreatment with androgen antagonist supports androgenic programming at the organizational level. PMID:25919188

Developmental Programming: Prenatal and Postnatal Androgen Antagonist and Insulin Sensitizer Interventions Prevent Advancement of Puberty and Improve LH Surge Dynamics in Prenatal Testosterone-Treated Sheep.

PubMed

Padmanabhan, Vasantha; Veiga-Lopez, Almudena; Herkimer, Carol; Abi Salloum, Bachir; Moeller, Jacob; Beckett, Evan; Sreedharan, Rohit

2015-07-01

Prenatal T excess induces maternal hyperinsulinemia, early puberty, and reproductive/metabolic defects in the female similar to those seen in women with polycystic ovary syndrome. This study addressed the organizational/activational role of androgens and insulin in programming pubertal advancement and periovulatory LH surge defects. Treatment groups included the following: 1) control; 2) prenatal T; 3) prenatal T plus prenatal androgen antagonist, flutamide; 4) prenatal T plus prenatal insulin sensitizer, rosiglitazone; 5) prenatal T and postnatal flutamide; 6) prenatal T and postnatal rosiglitazone; and 7) prenatal T and postnatal metformin. Prenatal treatments spanned 30-90 days of gestation and postnatal treatments began at approximately 8 weeks of age and continued throughout. Blood samples were taken twice weekly, beginning at approximately 12 weeks of age to time puberty. Two-hour samples after the synchronization with prostaglandin F2α were taken for 120 hours to characterize LH surge dynamics at 7 and 19 months of age. Prenatal T females entered puberty earlier than controls, and all interventions prevented this advancement. Prenatal T reduced the percentage of animals having LH surge, and females that presented LH surge exhibited delayed timing and dampened amplitude of the LH surge. Prenatal androgen antagonist, but not other interventions, restored LH surges without normalizing the timing of the surge. Normalization of pubertal timing with prenatal/postnatal androgen antagonist and insulin sensitizer interventions suggests that pubertal advancement is programmed by androgenic actions of T involving insulin as a mediary. Restoration of LH surges by cotreatment with androgen antagonist supports androgenic programming at the organizational level.

An evaluation of bacterial contamination of barriers used in periapical tissue regeneration: Part 2--Bacterial penetration.

PubMed

Sharma, Priya; Mickel, André K; Chogle, Sami; Sharma, Prem Nath; Han, Yiping W; Jones, Jefferson J

2008-03-01

To compare the relative penetration of Prevotella melaninogenica and Enterococcus faecalis through 3 guided tissue regeneration membranes: Atrisorb, Lambone, and OsseoQuest. It was hypothesized that OsseoQuest would show increased bacterial penetration when compared to Lambone and Atrisorb. Centrifuge tubes containing trypticase soy broth were sealed with circular sections of membranes and placed in test tubes containing culture media. The bacterial penetration was assessed by passage of bacteria from the outer tube culture media to the inner centrifuge tube media through the membrane. After incubation for 4 and 48 hours, the media from the outer and inner tubes were compared for bacterial count. P melaninogenica exhibited 91% penetration for Lambone in 2 days, while OsseoQuest displayed 87% penetration with E faecalis in the same time. Atrisorb displayed a minimal penetration with both bacteria (2%). Atrisorb displayed the least bacterial penetration, which may be attributed to membrane structure, chemical configuration, hydrophobicity, and porosity of tested membranes.

The relationship between LH and thyroid volume in patients with PCOS

PubMed Central

2012-01-01

Background Thyroid volume (TV) has been found to be associated with age, anthropometry, smoking, iodine status and hyperinsulinemia. Hyperinsulinemia is frequent finding in patients with PCOS and has associations with TV. However, the TV has been evaluated only a few studies in patients with PCOS. Therefore, the aim of this study was to evaluate the biochemical and hormonal variables in patients with PCOS comparing with the controls and their relationships between TV. Methods This was a case–control study conducted in a training and research hospital. The study population consisted of 47 reproductive-age PCOS women and 30 control subjects. We evaluated anthropometric, biochemical and hormonal parameters as well as thyroid volume in PCOS patients and controls. Insulin resistance was calculated using the homeostasis model assessment insulin resistance index (HOMA-IR). Results Mean age, BMI, thyroid stimulant hormone (TSH) levels and TV were similar between groups (p<0.05). The HOMA-IR and free T4 levels were higher in patients with PCOS. However, hyperinsulinemia and insulin resistance were not found to be associated with TV. Thyroid volume was positively correlated with the LH and anti TPO levels. The participants were divided into 2 groups according to HOMA-IR levels. The mean TV measurement was higher in group with higher HOMA-IR levels, but the difference was not significant in young age PCOS patients. Conclusion In early age PCOS patients it was observed that insulin resistance had no effect on TV. In this case, anti TPO and LH have dominant effect on TV. Chronic stimulation with LH and insulin may lead to increase in TV in later stages of the PCOS diseases. PMID:23231775

The energies and kinetics of triplet carotenoids in the LH2 antenna complexes as determined by phosphorescence spectroscopy

NASA Astrophysics Data System (ADS)

Rondonuwu, Ferdy S.; Taguchi, Tokio; Fujii, Ritsuko; Yokoyama, Kyosuke; Koyama, Yasushi; Watanabe, Yasutaka

2004-01-01

The triplet (T 1) states of carotenoids (Cars) and bacteriochlorophyll a (BChl) in the LH2 antenna complexes from Rhodobacter sphaeroides G1C, Rba. sphaeroides 2.4.1 and Rhodospirillum molischianum, containing neurosporene, spheroidene and lycopene, respectively, were examined by stationary-state and time-resolved phosphorescence spectroscopy. The T 1 energies of Cars were determined, irrespective of the Car or BChl excitation, to be 7030 cm -1 (neurosporene), 6920 cm -1 (spheroidene) and 6870 cm -1 (lycopene), respectively, whereas that of BChl to be 7590 cm -1. In the Rba. sphaeroides G1C, the Car and BChl triplet states decayed in similar time constant as the BChl Q y state, a fact which indicates that the pair of triplet states decays through the triplet-triplet annihilation mechanism.

Potential antidiabetic activity of extracellular polysaccharides in submerged fermentation culture of Coriolus versicolor LH1.

PubMed

Yang, John Powen; Hsu, Taihao; Lin, Fangyi; Hsu, Wenkuang; Chen, Yucheng

2012-09-01

The separation and purification of extracellular polysaccharides from Coriolus versicolor LH1 were investigated along with their α-glucosidase inhibition properties. Three polysaccharide fractions (ePS-F2-1, ePS-F3-1, and ePS-F4-1) were separated from the culture medium of LH1 using a DEAE anion-exchange column and a Sephadex™ G-50 gel filtration column. Their chemical compositions was determined. On the basis of an α-glucosidase inhibition assay, the enzyme inhibition activities of ePS-F2-1, ePS-F3-1, and ePS-F4-1 were investigated. Among these, ePS-F4-1 had the highest enzyme inhibition effects on α-glucosidase. According to the results of the chemical component analysis, ePS-F3-1 and ePS-F4-1 are the polysaccharides which are combined with triterpenoides, and ePS-F2-1 is complexed with proteins and triterpenoides. Copyright © 2012 Elsevier Ltd. All rights reserved.

Excitation energy transfer from the bacteriochlorophyll Soret band to carotenoids in the LH2 light-harvesting complex from Ectothiorhodospira haloalkaliphila is negligible.

PubMed

Razjivin, A P; Lukashev, E P; Kompanets, V O; Kozlovsky, V S; Ashikhmin, A A; Chekalin, S V; Moskalenko, A A; Paschenko, V Z

2017-09-01

Pathways of intramolecular conversion and intermolecular electronic excitation energy transfer (EET) in the photosynthetic apparatus of purple bacteria remain subject to debate. Here we experimentally tested the possibility of EET from the bacteriochlorophyll (BChl) Soret band to the singlet S 2 level of carotenoids using femtosecond pump-probe measurements and steady-state fluorescence excitation and absorption measurements in the near-ultraviolet and visible spectral ranges. The efficiency of EET from the Soret band of BChl to S 2 of the carotenoids in light-harvesting complex LH2 from the purple bacterium Ectothiorhodospira haloalkaliphila appeared not to exceed a few percent.

Plant-associated bacterial populations on native and invasive plant species: comparisons between 2 freshwater environments.

PubMed

Olapade, Ola A; Pung, Kayleigh

2012-06-01

Plant-microbial interactions have been well studied because of the ecological importance of such relationships in aquatic systems. However, general knowledge regarding the composition of these biofilm communities is still evolving, partly as a result of several confounding factors that are attributable to plant host properties and to hydrodynamic conditions in aquatic environments. In this study, the occurrences of various bacterial phylogenetic taxa on 2 native plants, i.e., mayapple (Podophyllum peltatum L.) and cow parsnip (Heracleum maximum Bartram), and on an invasive species, i.e., garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande), were quantitatively examined using nucleic acid staining and fluorescence in situ hybridization. The plants were incubated in triplicates for about a week within the Kalamazoo River and Pierce Cedar Creek as well as in microcosms. The bacterial groups targeted for enumeration are known to globally occur in relatively high abundance and are also ubiquitously distributed in freshwater environments. Fluorescence in situ hybridization analyses of the bacterioplankton assemblages revealed that the majority of bacterial cells that hybridized with the different probes were similar between the 2 sites. In contrast, the plant-associated populations while similar on the 3 plants incubated in Kalamazoo River, their representations were highest on the 2 native plants relative to the invasive species in Pierce Cedar Creek. Overall, our results further suggested that epiphytic bacterial assemblages are probably under the influences of and probably subsequently respond to multiple variables and conditions in aquatic milieus.

Lack of Toll-like receptor 2 results in higher mortality of bacterial meningitis by impaired host resistance.

PubMed

Böhland, Martin; Kress, Eugenia; Stope, Matthias B; Pufe, Thomas; Tauber, Simone C; Brandenburg, Lars-Ove

2016-10-15

Bacterial meningitis is - despite therapeutical progress during the last decades - still characterized by high mortality and severe permanent neurogical sequelae. The brain is protected from penetrating pathogens by both the blood-brain barrier and the innate immune system. Invading pathogens are recognized by so-called pattern recognition receptors including the Toll-like receptors (TLR) which are expressed by glial immune cells in the central nervous system. Among these, TLR2 is responsible for the detection of Gram-positive bacteria such as the meningitis-causing pathogen Streptococcus pneumoniae. Here, we used TLR2-deficient mice to investigate the effects on mortality, bacterial growth and inflammation in a mouse model of pneumococcal meningitis. Our results revealed a significantly increased mortality rate and higher bacterial burden in TLR2-deficient mice with pneumococcal meningitis. Furthermore, infected TLR2-deficient mice suffered from a significantly increased pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) and Chemokine (C-C motif) ligand 2 (CCL2) or CCL3 chemokine expression and decreased expression of anti-inflammatory cytokines and antimicrobial peptides. In contrast, glial cell activation assessed by glial cell marker expression was comparable to wildtype mice. Taken together, the results suggest that TLR2 is essential for an efficient immune response against Streptococcus pneumoniae meningitis since lack of the receptor led to a worse outcome by higher mortality due to increased bacterial burden, weakened innate immune response and reduced expression of antimicrobial peptides. Copyright © 2016 Elsevier B.V. All rights reserved.

ASME Section VIII Recertification of a 33,000 Gallon Vacuum-jacketed LH2 Storage Vessel for Densified Hydrogen Testing at NASA Kennedy Space Center

NASA Technical Reports Server (NTRS)

Swanger, Adam M.; Notardonato, William U.; Jumper, Kevin M.

2015-01-01

The Ground Operations Demonstration Unit for Liquid Hydrogen (GODU-LH2) has been developed at NASA Kennedy Space Center in Florida. GODU-LH2 has three main objectives: zero-loss storage and transfer, liquefaction, and densification of liquid hydrogen. A cryogenic refrigerator has been integrated into an existing, previously certified, 33,000 gallon vacuum-jacketed storage vessel built by Minnesota Valley Engineering in 1991 for the Titan program. The dewar has an inner diameter of 9.5 and a length of 71.5; original design temperature and pressure ranges are -423 F to 100 F and 0 to 95 psig respectively. During densification operations the liquid temperature will be decreased below the normal boiling point by the refrigerator, and consequently the pressure inside the inner vessel will be sub-atmospheric. These new operational conditions rendered the original certification invalid, so an effort was undertaken to recertify the tank to the new pressure and temperature requirements (-12.7 to 95 psig and -433 F to 100 F respectively) per ASME Boiler and Pressure Vessel Code, Section VIII, Division 1. This paper will discuss the unique design, analysis and implementation issues encountered during the vessel recertification process.

Extraordinary Structured Noncoding RNAs Revealed by Bacterial Metagenome Analysis

PubMed Central

Weinberg, Zasha; Perreault, Jonathan; Meyer, Michelle M.; Breaker, Ronald R.

2012-01-01

Estimates of the total number of bacterial species1-3 suggest that existing DNA sequence databases carry only a tiny fraction of the total amount of DNA sequence space represented by this division of life. Indeed, environmental DNA samples have been shown to encode many previously unknown classes of proteins4 and RNAs5. Bioinformatics searches6-10 of genomic DNA from bacteria commonly identify novel noncoding RNAs (ncRNAs)10-12 such as riboswitches13,14. In rare instances, RNAs that exhibit more extensive sequence and structural conservation across a wide range of bacteria are encountered15,16. Given that large structured RNAs are known to carry out complex biochemical functions such as protein synthesis and RNA processing reactions, identifying more RNAs of great size and intricate structure is likely to reveal additional biochemical functions that can be achieved by RNA. We applied an updated computational pipeline17 to discover ncRNAs that rival the known large ribozymes in size and structural complexity or that are among the most abundant RNAs in bacteria that encode them. These RNAs would have been difficult or impossible to detect without examining environmental DNA sequences, suggesting that numerous RNAs with extraordinary size, structural complexity, or other exceptional characteristics remain to be discovered in unexplored sequence space. PMID:19956260

Circulating breeding and pre-breeding prolactin and LH are not associated with clutch size in the zebra finch (Taeniopygia guttata).

PubMed

Ryan, Calen P; Dawson, Alistair; Sharp, Peter J; Meddle, Simone L; Williams, Tony D

2014-06-01

Clutch size is a fundamental predictor of avian fitness, widely-studied from evolutionary and ecological perspectives, but surprisingly little is known about the physiological mechanisms regulating clutch size variation. The only formal mechanistic hypothesis for avian clutch-size determination predicts an anti-gonadal effect of circulating prolactin (PRL) via the inhibition of luteinizing hormone (LH), and has become widely-accepted despite little experimental support. Here we investigated the relationship between pre-breeding and breeding plasma PRL and LH and clutch-size in captive-breeding female zebra finches (Taeniopygia guttata). Using a repeated-measures design, we followed individual females from pre-breeding, through multiple breeding attempts, and attempted to decrease PRL using the D2-receptor agonist, bromocriptine. Clutch size was independent of variation in pre-breeding PRL or LH, although pre-breeding LH was negatively correlated with the time between pairing and the onset of laying. Clutch size was independent of variation in plasma PRL on all days of egg-laying. Bromocriptine treatment had no effect on plasma PRL, but in this breeding attempt clutch size was also independent of plasma PRL. Finally, we found no evidence for an inverse relationship between plasma PRL and LH levels, as predicted if PRL had inhibitory effects via LH. Thus, our data fail to provide any support for the involvement of circulating PRL in clutch size determination. These findings suggest that alternative models for hormonal control of avian clutch size need to be considered, perhaps involving downstream regulation of plasma PRL at the level of the ovary, or other hormones that have not been considered to date. Copyright © 2014 Elsevier Inc. All rights reserved.

Stability and properties of quasi-stable conformational states in the LH2 light-harvesting complex of Rbl. acidophilus bacteria formed by hexacoordination of bacteriochlorophyll a magnesium atom

NASA Astrophysics Data System (ADS)

Belov, Aleksandr S.; Khokhlov, Daniil V.; Glebov, Ilya O.; Poddubnyy, Vladimir V.; Eremin, Vadim V.

2017-06-01

Single-molecule spectroscopic experiments on several light-harvesting complexes revealed the existence of a set of metastable conformational states with different spectroscopic properties and lifetimes spanning from milliseconds to tens of seconds. In the absence of explicit structural data, a number of probable structural changes underlying the observed spectroscopic shifts were proposed. We examine the donor-acceptor interaction between the magnesium atom and the acetyl group of the adjacent bacteriochlorophylls a as a possible origin of metastable conformational states in the LH2 light-harvesting complex of Rbl. acidophilus bacteria. The results of QM/MM and molecular dynamics simulations show that such ligation can occur at room temperature and leads to one metastable coordination bond per pair of bacteriochlorophylls in the B850 ring. According to the results of Poisson-TrESP modeling, such coordination lowers the energies of the excited states of the complex by up to 163 cm-1 which causes red spectral shift of the B850 band.

LH Power Losses In Front of the JET Launcher

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacquet, P.; Arnoux, G.; Kirov, K.

2009-11-26

In recent JET experiments, Lower Hybrid (LH) power losses in the Scrape-Off Layer (SOL) were characterized using infra-red (IR) thermography. Hot spots were observed on objects intercepting the field lines passing in front of the LH launcher, i.e. on poloidal limiters and on dumplates located at the top of the tokamak; their locations being in good agreement with magnetic field line tracing using the EFIT equilibrium code. The dumplate temperature was monitored while scanning the launcher position so that the radial distance between field lines intercepting the hot spots and the launcher was increased up to 3.5 cm. The dissipationmore » layer in front of the launcher was estimated to be at least 3.5 cm wide, in agreement with recent measurements on Tore-Supra, but not with simple models that predict a dissipation layer in the mm range.« less

Comparison of the effect of natural mating, LH, and GnRH on interval to ovulation and luteal function in llamas.

PubMed

Ratto, Marcelo; Huanca, Wilfredo; Singh, Jaswant; Adams, Gregg P

2006-02-01

Gonadotropins and GnRH have been used to electively induce ovulation in llamas and alpacas, but critical evaluation of the natural interval to ovulation after mating has not been performed nor has a direct comparison of the effects of natural mating versus hormone treatments on this interval and subsequent luteal development. The objectives of this study were to compare the effects of hormonal treatments and natural mating on ovulation induction, interval to ovulation, and luteal development in llamas. The ovaries of llamas were examined by transrectal ultrasonography once daily. Llamas with a large follicle were assigned randomly to be: (1) mated with an intact male (mated; n=10); (2) given 5 mg of LH im (LH; n=11); or (3) 50 microg of GnRH im (GnRH; n=10). Ultrasound examinations were performed every 4h from treatment (day 0) to ovulation and thereafter once daily for 15 consecutive days to monitor CL growth and regression (n=5 per group). Plasma progesterone concentrations were measured at days 0, 3, 6, 9, and 12 after treatment to evaluate CL function. The size of the largest preovulatory follicle at the time of treatment did not differ among groups (11+/-0.6, 10.5+/-0.8, 11.8+/-0.9 mm, for mated, LH, and GnRH groups, respectively; P=0.6). No differences were detected among groups (mated, LH, and GnRH) in ovulation rate (80%, 91%, 80%, respectively; P=0.6), or interval from treatment to ovulation (30.0+/-0.5, 29.3+/-0.6, 29.3+/-0.7h, respectively; P=0.9). Similarly, no differences were detected among groups (mated, LH, and GnRH) in maximum CL diameter (14.2+/-0.3, 13.2+/-0.5, and 13.0+/-0.7 mm, respectively; P=0.5), the day of maximum CL diameter (7.6+/-0.2, 7.6+/-0.2, and 7.4+/-0.4 mm, respectively; P=0.6), or the day on which the CL began to regress (12.3+/-0.3 [non-pregnant, n=3], 11.8+/-0.6, 12.2+/-0.4, respectively; P=0.4). The diameter of the CL and plasma progesterone concentrations changed over days (P<0.0001) but the profiles did not differ among

Intermolecular Modes between LH2 Bacteriochlorophylls and Protein Residues: The Effect on the Excitation Energies.

PubMed

Anda, André; De Vico, Luca; Hansen, Thorsten

2017-06-08

Light-harvesting system 2 (LH2) executes the primary processes of photosynthesis in purple bacteria; photon absorption, and energy transportation to the reaction center. A detailed mechanistic insight into these operations is obscured by the complexity of the light-harvesting systems, particularly by the chromophore-environment interaction. In this work, we focus on the effects of the protein residues that are ligated to the bacteriochlorophylls (BChls) and construct potential energy surfaces of the ground and first optically excited state for the various BChl-residue systems where we in each case consider two degrees of freedom in the intermolecular region. We find that the excitation energies are only slightly affected by the considered modes. In addition, we see that axial ligands and hydrogen-bonded residues have opposite effects on both excitation energies and oscillator strengths by comparing to the isolated BChls. Our results indicate that only a small part of the chromophore-environment interaction can be associated with the intermolecular region between a BChl and an adjacent residue, but that it may be possible to selectively raise or lower the excitation energy at the axial and planar residue positions, respectively.

Comparative effects of sub-stimulating concentrations of non-human versus human Luteinizing Hormones (LH) or chorionic gonadotropins (CG) on adenylate cyclase activation by forskolin in MLTC cells.

PubMed

Nguyen, Thi-Mong Diep; Filliatreau, Laura; Klett, Danièle; Combarnous, Yves

2018-05-15

We have compared various Luteinizing Hormone (LH) and Chorionic Gonadotropin (CG) preparations from non-human and human species in their ability to synergize with 10 µM forskolin (FSK) for cyclic AMP intracellular accumulation, in MLTC cells. LH from rat pituitary as well as various isoforms of pituitary ovine, bovine, porcine, equine and human LHs and equine and human CG were studied. In addition, recombinant human LH and CG were also compared with the natural human and non-human hormones. Sub-stimulating concentrations of all LHs and CGs (2-100 pM) were found to stimulate cyclic AMP accumulation in MLTC cells in the presence of an also non-stimulating FSK concentration (10 µM). Like rat LH, the most homologous available hormone for mouse MLTC cells, all non-human LHs and CG exhibit a strong potentiating effect on FSK response. The human, natural and recombinant hLH and hCG also do so but in addition, they were found to elicit a permissive effect on FSK stimulation. Indeed, when incubated alone with MLTC cells at non-stimulating concentrations (2-70 pM) hLH and hCG permit, after being removed, a dose-dependent cyclic AMP accumulation with 10 µM FSK. Our data show a clearcut difference between human LH and CG compared to their non-human counterparts on MLTC cells adenylate cyclase activity control. This points out the risk of using hCG as a reference ligand for LHR in studies using non-human cells. Copyright © 2018 Elsevier Inc. All rights reserved.

Body mass index and gonadotropin hormones (LH & FSH) associate with clinical symptoms among women with polycystic ovary syndrome.

PubMed

Esmaeilzadeh, Seddigheh; Andarieh, Maryam Ghanbari; Ghadimi, Reza; Delavar, Mouloud Agajani

2014-09-28

To evaluate the relevance of body mass index (BMI), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and LH/FSH ratio with clinical symptoms in polycystic ovary syndrome (PCOS) women. We reviewed the medical records of all women visited in the PCOS Clinic of Babol (Iran) from 2008 to 2012. A retrospective cross-sectional study was conducted on 175 PCOS women; aged 18-38 years diagnosed based on the Rotterdam criteria. Among the PCOs women, the prevalence of oligomenorrhea, acne, and hirsutism were found to be 92.0%, 31.4%, and 78.9%, respectively. Positive finding of polycystic ovaries was observed in 89.1% of PCOS women with by using sonography. A total of 69.2% overweight/obesity patients had polycystic ovary morphology on ultrasound image. Compared with non- overweight/obesity, the adjusted OR of PCOS women for sonographic view of polycystic ovaries was 4.33 (95% CI, 1.42-13.15, p=0.001), Nevertheless, the adjusted odds ratio (OR) showed no significant associations between LH, FSH, and LH/FSH ratio with clinical symptoms in these women. The findings of this study indicated that the overweight/obese women with PCOS are at an increased risk for sonographic view of polycystic ovaries. Therefore, it is suggested that successful weight loss is the most effective method of restoring ovulation, menstruation that should be used as major advice in obese PCOS patients.

Multi-Level, Multi Time-Scale Fluorescence Intermittency of Photosynthetic LH2 Complexes: A Precursor of Non-Photochemical Quenching?

PubMed

Schörner, Mario; Beyer, Sebastian Reinhardt; Southall, June; Cogdell, Richard J; Köhler, Jürgen

2015-11-05

The light harvesting complex LH2 is a chromoprotein that is an ideal system for studying protein dynamics via the spectral fluctuations of the emission of its intrinsic chromophores. We have immobilized these complexes in a polymer film and studied the fluctuations of the fluorescence intensity from individual complexes over 9 orders of magnitude in time. Combining time-tagged detection of single photons with a change-point analysis has allowed the unambigeous identification of the various intensity levels due to the huge statistical basis of the data set. We propose that the observed intensity level fluctuations reflect conformational changes of the protein backbone that might be a precursor of the mechanism from which nonphotochemical quenching of higher plants has evolved.

Effect of kisspeptin-10, LH and hCG on serum testosterone concentrations in stallions, donkeys and mules.

PubMed

Akhtar, Rana Waseem; Shah, Syed Aftab Hussain; Qureshi, Irfan Zia

2017-10-15

This study was conducted to determine the response of serum testosterone (T) in male equines (stallions, donkeys and mules) after administering intravenous doses of kisspeptin-10 (KP-10), human chorionic gonadotropin (hCG) and luteinizing hormone (LH) and saline as a control. The animals were divided into four groups of three each: Group I, 3 ml of 0.95% saline; Group II, 50 μg KP-10; Group III, 2500 IU hCG and group IV, 400 μg LH. The administration of KP-10 and hCG to stallions resulted in a significant increase in serum T concentration at 240 min; whereas it was significantly higher at 30, 60, 120, and 240 min with LH treatment as compared to pre-dose concentrations. Both KP-10 and hCG significantly elevated the T concentrations in donkeys at 120 and 240 min, respectively; whereas it was significantly higher at 60, 120, and 240 min with LH treatment as compared to pre-dose concentration. Both KP-10 and LH elevated T in donkeys at 240 min as compared to the control and hCG concentrations. After 120 and 240 min, T concentrations in mules were higher (p < 0.05) with administration of KP-10, hCG and LH as compared to the control. In conclusion, the administration of KP-10, hCG and LH elevate the serum T concentration in normal male equines. It is suggested that KP-10 may be useful in situations where an increase in T is desired. Further work is required to determine the effect of KP-10 on T in male equids with reproductive abnormalities before it can be used in clinical situations. Copyright © 2017 Elsevier Inc. All rights reserved.

Separation, purification, and α-glucosidase inhibition of polysaccharides from Coriolus versicolor LH1 mycelia.

PubMed

Hsu, Wen-kuang; Hsu, Tai-hao; Lin, Fang-yi; Cheng, Yuan-kai; Yang, John Po-wen

2013-01-30

Intracellular polysaccharides (iPs) were separated and purified from Coriolus versicolor LH1 mycelia and characterized for their α-glucosidase inhibitory properties. Three iP fractions (iPL-F5-2-1, iPL-F5-4-1, and iPL-F5-5-1) were extracted, separated, and purified from LH1 mycelia using microwave extraction technology, a DEAE-Sepharose CL-6B column, a Diaion HP20 macroporous adsorption column, and a Sephadex™ G-50 gel-permeation column. The principal constituents of iPL-F5-2-1, iPL-F5-4-1, and iPL-F5-5-1 were saponins and polyphenoic compound mixtures. The enzyme inhibition activity, IC(50) values, of these three fractions were 1.7, 1.8, and 0.8 mg/mL, respectively. The α-glucosidase inhibitory properties were related to the presence of α-(1,4) glycosidic linkages in the polysaccharide structure and the total relative percentage of d-glucose and d-galactose in the structure of polysaccharides, other than triterpenoids. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bacterial community composition in the gut content of Lampetra japonica revealed by 16S rRNA gene pyrosequencing.

PubMed

Zuo, Yu; Xie, Wenfang; Pang, Yue; Li, Tiesong; Li, Qingwei; Li, Yingying

2017-01-01

The composition of the bacterial communities in the hindgut contents of Lampetrs japonica was surveyed by Illumina MiSeq of the 16S rRNA gene. An average of 32385 optimized reads was obtained from three samples. The rarefaction curve based on the operational taxonomic units tended to approach the asymptote. The rank abundance curve representing the species richness and evenness was calculated. The composition of microbe in six classification levels was also analyzed. Top 20 members in genera level were displayed as the classification tree. The abundance of microorganisms in different individuals was displayed as the pie charts at the branch nodes in the classification tree. The differences of top 50 genera in abundance between individuals of lamprey are displayed as a heatmap. The pairwise comparison of bacterial taxa abundance revealed that there are no significant differences of gut microbiota between three individuals of lamprey at a given rarefied depth. Also, the gut microbiota derived from L. japonica displays little similarity with other aquatic organism of Vertebrata after UPGMA analysis. The metabolic function of the bacterial communities was predicted through KEGG analysis. This study represents the first analysis of the bacterial community composition in the gut content of L. japonica. The investigation of the gut microbiota associated with L. japonica will broaden our understanding of this unique organism.

Highly purified hMG versus recombinant FSH plus recombinant LH in intrauterine insemination cycles in women ≥35 years: a RCT.

PubMed

Moro, Francesca; Scarinci, Elisa; Palla, Carola; Romani, Federica; Familiari, Alessandra; Tropea, Anna; Leoncini, Emanuele; Lanzone, Antonio; Apa, Rosanna

2015-01-01

.3%) in the recombinant group versus 35/289 (12.2%) in the HP-hMG group [(odds ratio (OR) 1.50, 95% CI 0.94-2.41, P = 0.09]. The number of interrupted cycles for high risk of OHSS was 13/290 (4.5%) in the rFSH plus rLH group and 2/289 (0.7%) in the HP-hMG group (OR 6.73, 95% CI 1.51-30.12, P = 0.013). One of the limitations of this study was the early closure and the ongoing PR could be overestimated. Both patient and gynaecologist were informed of the assigned treatment. Our results demonstrated the lack of differences in terms of ongoing PR between recombinant product and HP-hMG, in women ≥35 years undergoing controlled ovarian stimulation for IUI cycles. HP-hMG was safer than recombinant gonadotrophin concerning the risk of OHSS. None. NCT01604044. © The Author 2014. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Analysis of multiple positive feedback paradigms demonstrates a complete absence of LH surges and GnRH activation in mice lacking kisspeptin signaling.

PubMed

Dror, Tal; Franks, Jennifer; Kauffman, Alexander S

2013-06-01

Kisspeptin stimulates gonadotropin-releasing hormone (GnRH) neurons via the kisspeptin receptor, Kiss1r. In rodents, estrogen-responsive kisspeptin neurons in the rostral hypothalamus have been postulated to mediate estrogen-induced positive feedback induction of the preovulatory luteinizing hormone (LH) surge. However, conflicting evidence exists regarding the ability of mice lacking Kiss1r to display LH surges in response to exogenous hormones. Whether the discrepancy reflects different mouse strains used and/or utilization of different surge-induction paradigms is unknown. Here, we tested multiple hormonal paradigms in one Kiss1r knockout (KO) model to see which paradigms, if any, could generate circadian-timed LH surges. Kiss1r KO and wild-type (WT) females were ovariectomized, given sex steroids in various modes, and assessed several days later for LH levels in the morning or evening (when surges occur). Serum LH levels were very low in all morning animals, regardless of genotype or hormonal paradigm. In each paradigm, virtually all WT females displayed clear LH surges in the evening, whereas none of the KO females demonstrated LH surges. The lack of LH surges in KO mice reflects a lack of GnRH secretion rather than diminished pituitary responsiveness from a lifetime lack of GnRH exposure because KO mice responded to GnRH priming with robust LH secretion. Moreover, high cfos-GnRH coexpression was detected in WT females in the evening, whereas low cfos-GnRH coexpression was present in KO females at all time points. Our findings conclusively demonstrate that WT females consistently display LH surges under multiple hormonal paradigms, whereas Kiss1r KO mice do not, indicating that kisspeptin-Kiss1r signaling is mandatory for GnRH/LH surge induction.

Lipocalin 2 in cerebrospinal fluid as a marker of acute bacterial meningitis

PubMed Central

2014-01-01

Background Early differential diagnosis between acute bacterial and viral meningitis is problematic. We aimed to investigate whether the detection of lipocalin 2, a protein of the acute innate immunity response, may be used as a marker for acute bacterial meningitis. Methods Transgenic mice expressing the human transferrin were infected by intraperitoneal route and were imaged. Cerebrospinal fluid (CSF) was sampled up to 48hours post- infection to measure lipocalin 2. We also tested a collection of 90 and 44 human CSF with confirmed acute bacterial or acute viral meningitis respectively. Results Lipocalin 2 was detected after 5 h in CSF during experimental infection in mice. Lipocalin 2 levels were significantly higher (p < 0.0001) in patients with confirmed acute bacterial meningitis (mean 125 pg/mL, range 106–145 pg/mL) than in patients with acute viral meningitis (mean 2 pg/mL, range 0–6 pg/mL) with a sensitivity of 81%, a specificity of 93%, a positive predictive value of 96% and a negative predictive value of 71% in diagnosing acute bacterial meningitis. Conclusions Increased levels of lipocalin 2 in cerebrospinal fluid may discriminate between acute bacterial and viral meningitis in patients with clinical syndrome of meningitis. PMID:24885531

Establishing bacterial communities by 'word of mouth': LuxS and autoinducer 2 in biofilm development.

PubMed

Hardie, Kim Rachael; Heurlier, Karin

2008-08-01

Multicellular bacterial communities (biofilms) abound in nature, and their successful formation and survival is likely to require cell-cell communication--including quorum sensing--to co-ordinate appropriate gene expression. The only mode of quorum sensing that is shared by both Gram-positive and Gram-negative bacteria involves the production of the signalling molecule autoinducer 2 by LuxS. A survey of the current literature reveals that luxS contributes to biofilm development in some bacteria. However, inconsistencies prevent biofilm development being attributed to the production of AI2 in all cases.

Construction and Structural Analysis of Tethered Lipid Bilayer Containing Photosynthetic Antenna Proteins for Functional Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sumino, Ayumi; Dewa, Takehisa; Takeuchi, Toshikazu

2011-07-11

The construction and structural analysis of a tethered planar lipid bilayer containing bacterial photosynthetic membrane proteins, light-harvesting complex 2 (LH2), and light-harvesting core complex (LH1-RC) is described and establishes this system as an experimental platform for their functional analysis. The planar lipid bilayer containing LH2 and/or LH1-RC complexes was successfully formed on an avidin-immobilized coverglass via an avidin-biotin linkage. Atomic force microscopy (AFM) showed that a smooth continuous membrane was formed there. Lateral diffusion of these membrane proteins, observed by a fluorescence recovery after photobleaching (FRAY), is discussed in terms of the membrane architecture. Energy transfer from LH2 to LH1-RCmore » within the tethered membrane architecture. Energy transfer from LH2 to LH1-RC within the tethered membrane was observed by steady-state fluorescence spectroscopy, indicating that the tethered membrane can mimic the natural situation.« less

L-H transition and pedestal studies on MAST

NASA Astrophysics Data System (ADS)

Meyer, H.; De Bock, M. F. M.; Conway, N. J.; Freethy, S. J.; Gibson, K.; Hiratsuka, J.; Kirk, A.; Michael, C. A.; Morgan, T.; Scannell, R.; Naylor, G.; Saarelma, S.; Saveliev, A. N.; Shevchenko, V. F.; Suttrop, W.; Temple, D.; Vann, R. G. L.; MAST, the; NBI Teams

2011-11-01

On MAST studies of the profile evolution of the electron temperature (Te), electron density (ne), radial electric field (Er) as well as novel measurements of the ion temperature (Ti) and toroidal current density (jphi) in the pedestal region allow further insight into the processes forming and defining the pedestal such as the H-mode access conditions and MHD stability. This includes studies of fast evolution of Te, ne and Er with Δt = 0.2 ms time resolution and the evolution of pe and jphi through an edge-localized mode (ELM) cycle. Measurements of the H-mode power threshold, PL-H revealed that about 40% more power is required to access H-mode in 4He than in D and that a change in the Z-position of the X-point can change PL-H significantly in single and double null configurations. The profile measurements in the L-mode phase prior to H-mode suggest that neither the gradient nor the value of the mean Te or Er at the plasma edge play a major role in triggering the L-H transition. After the transitions, first the fluctuations are suppressed, then the Er shear layer and the ne pedestal develops followed by the Te pedestal. In the banana regime at low collisionality (νsstarf) ∇Ti ≈ 0 leading to Ti > Te in the pedestal region with Ti ~ 0.3 keV close to the separatrix. A clear correlation of ∇Ti with νsstarf is observed. The measured jphi (using the motional Stark effect) Te and ne are in broad agreement with the common peeling-ballooning stability picture for ELMs and neoclassical calculations of the bootstrap current. The jphi and ∇pe evolution Δt ≈ 2 ms as well as profiles in discharges with counter current neutral beam injection raise questions with respect to this edge stability picture.

Age-specific changes in the regulation of LH-dependent testosterone secretion: assessing responsiveness to varying endogenous gonadotropin output in normal men.

PubMed

Liu, Peter Y; Takahashi, Paul Y; Roebuck, Pamela D; Iranmanesh, Ali; Veldhuis, Johannes D

2005-09-01

Pulsatile and thus total testosterone (Te) secretion declines in older men, albeit for unknown reasons. Analytical models forecast that aging may reduce the capability of endogenous luteinizing hormone (LH) pulses to stimulate Leydig cell steroidogenesis. This notion has been difficult to test experimentally. The present study used graded doses of a selective gonadotropin releasing hormone (GnRH)-receptor antagonist to yield four distinct strata of pulsatile LH release in each of 18 healthy men ages 23-72 yr. Deconvolution analysis was applied to frequently sampled LH and Te concentration time series to quantitate pulsatile Te secretion over a 16-h interval. Log-linear regression was used to relate pulsatile LH secretion to attendant pulsatile Te secretion (LH-Te drive) across the four stepwise interventions in each subject. Linear regression of the 18 individual estimates of LH-Te feedforward dose-response slopes on age disclosed a strongly negative relationship (r = -0.721, P < 0.001). Accordingly, the present data support the thesis that aging in healthy men attenuates amplitude-dependent LH drive of burst-like Te secretion. The experimental strategy of graded suppression of neuroglandular outflow may have utility in estimating dose-response adaptations in other endocrine systems.

Effects and interactions of tachykinins and dynorphin on FSH and LH secretion in developing and adult rats.

PubMed

Ruiz-Pino, F; Garcia-Galiano, D; Manfredi-Lozano, M; Leon, S; Sánchez-Garrido, M A; Roa, J; Pinilla, L; Navarro, V M; Tena-Sempere, M

2015-02-01

Kisspeptin/neurokinin B/dynorphin (KNDy) neurons, which coexpress kisspeptins (Kps), neurokinin B (NKB), and dynorphin (Dyn), regulate gonadotropin secretion. The KNDy model proposes that NKB (a stimulator, through NK3R) and Dyn (an inhibitor, through κ-opioid receptor) shape Kp secretion onto GnRH neurons. However, some aspects of this paradigm remain ill defined. Here we aimed to characterize the following: 1) the effects of NKB signaling on FSH secretion and 2) the role of Dyn in gonadotropin secretion after NK3R activation; 3) additionally, we explored the roles of other tachykinin receptors, NK1R and NK2R, on gonadotropin release. Thus, the effects of the NK3R agonist, senktide, on FSH release were explored across postnatal development in male and female rats; gonadotropin responses to agonists of NK1R substance P and NK2R [neurokinin A (NKA)] were also monitored. Moreover, the effects of senktide on gonadotropin secretion were assessed after antagonizing Dyn actions by nor-binaltorphimine didydrochloride. Before puberty, rats of both sexes showed increased FSH secretion to senktide (and Kp-10). Conversely, adult female rats were irresponsive to senktide in terms of FSH, despite proven LH responses, whereas the adult males did not display FSH or LH responses to senktide, even at high doses. In turn, substance P and NKA stimulated gonadotropin secretion in prepubertal rats, whereas in adults modest gonadotropin responses to NKA were detected. By pretreatment with a Dyn antagonist, adult males became responsive to senktide in terms of LH secretion and displayed elevated basal LH and FSH levels; nor-binaltorphimine didydrochloride treatment uncovered FSH responses to senktide in adult females. Furthermore, the expression of Pdyn and Opkr1 (encoding Dyn and κ-opioid receptor, respectively) in the mediobasal hypothalamus was greater in males than in females at prepubertal ages. Overall, our data contribute to refining our understanding on how the elements of the

Temporal concentrations of cortisol and LH in virgin ewes acutely exposed to rams during the transition into the breeding season.

PubMed

McCosh, R B; Berry, E M; Wehrman, M E; Redden, R R; Hallford, D M; Berardinelli, J G

2015-03-01

The objectives of this study were to determine if exposing seasonally anovular ewes to rams would alter patterns of cortisol concentrations, and if these changes are associated with changes in characteristics of LH concentrations. Seasonally anestrous ewes were assigned to be exposed to rams (RE; n=11) or wethers (NE; n=12). Blood samples were collected at 15-min intervals beginning 120 min before introduction of males (time=0 min), and continued for 360 min after male exposure. Characteristics of cortisol and LH concentrations included: mean and baseline concentrations, pulse amplitude, duration, frequency, and time to first pulse. Mean and baseline cortisol concentrations, and cortisol pulse amplitude, frequency, and time to first pulse after male exposure did not differ between RE and NE ewes. Cortisol pulse duration was longer (P<0.05) in RE ewes than in NE ewes. Mean LH and LH pulse amplitude, duration, and time to first pulse after male exposure did not differ between RE and NE ewes. Baseline LH concentrations and LH pulse frequency were greater (P<0.05) in RE than in NE ewes. In RE ewes, but not NE ewes, LH pulse frequency tended to increase (P=0.06) as pulse frequency of cortisol decreased. In conclusion, exposing ewes to mature rams during the transition into the breeding season increased LH pulse frequency which hastened ovulatory activity. However, the results do not support the hypothesis that changes in cortisol concentrations plays a significant role in the 'ram effect'. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of RFamide-related peptide-3(RFRP-3) on secretion of LH in ovariectomized prepubertal gilts

USDA-ARS?s Scientific Manuscript database

Pulses of LH are suppressed prior to puberty in the gilt. RFRP-3 is proposed to be a hypophysiotropic hormone in mammals. A series of experiments (EXP) were conducted to test the hypothesis that RFRP-3 inhibits LH release in ovariectomized (OVX) prepubertal gilts. All gilts were OVX at least two wee...

Bacterial assemblages of the eastern Atlantic Ocean reveal both vertical and latitudinal biogeographic signatures

NASA Astrophysics Data System (ADS)

Friedline, C. J.; Franklin, R. B.; McCallister, S. L.; Rivera, M. C.

2012-06-01

Microbial communities are recognized as major drivers of the biogeochemical processes in the oceans. However, the genetic diversity and composition of those communities is poorly understood. The aim of this study is to investigate the composition of bacterial assemblages in three different water layer habitats: surface (2-20 m), deep chlorophyll maximum (DCM; 28-90 m), and deep (100-4600 m) at nine stations along the eastern Atlantic Ocean from 42.8° N to 23.7° S. The sampling of three discrete, predefined habitat types from different depths, Longhurstian provinces, and geographical locations allowed us to investigate whether marine bacterial assemblages show spatial variation and to determine if the observed spatial variation is influenced by current environmental conditions, historical/geographical contingencies, or both. The PCR amplicons of the V6 region of the 16S rRNA from 16 microbial assemblages were pyrosequenced, generating a total of 352 029 sequences; after quality filtering and processing, 257 260 sequences were clustered into 2871 normalized operational taxonomic units (OTU) using a definition of 97% sequence identity. Community ecology statistical analyses demonstrate that the eastern Atlantic Ocean bacterial assemblages are vertically stratified and associated with water layers characterized by unique environmental signals (e.g., temperature, salinity, and nutrients). Genetic compositions of bacterial assemblages from the same water layer are more similar to each other than to assemblages from different water layers. The observed clustering of samples by water layer allows us to conclude that contemporary environments are influencing the observed biogeographic patterns. Moreover, the implementation of a novel Bayesian inference approach that allows a more efficient and explicit use of all the OTU abundance data shows a distance effect suggesting the influence of historical contingencies on the composition of bacterial assemblages. Surface

Targeting Nrf2 Signaling Improves Bacterial Clearance by Alveolar Macrophages in Patients with COPD and in a Mouse Model

PubMed Central

Harvey, Christopher J.; Thimmulappa, Rajesh K.; Sethi, Sanjay; Kong, Xiaoni; Yarmus, Lonny; Brown, Robert H.; David, Feller-Kopman; Wise, Robert; Biswal, Shyam

2016-01-01

Patients with chronic obstructive pulmonary disease (COPD) have innate immune dysfunction in the lung largely due to defective macrophage phagocytosis. This deficiency results in periodic bacterial infections that cause acute exacerbations of COPD, a major source of morbidity and mortality. Recent studies indicate that a decrease in Nrf2 (nuclear erythroid–related factor 2) signaling in patients with COPD may hamper their ability to defend against oxidative stress, although the role of Nrf2 in COPD exacerbations has not been determined. Here, we test whether activation of Nrf2 by the phytochemical sulforaphane restores phagocytosis of clinical isolates of nontypeable Haemophilus influenza (NTHI) and Pseudomonas aeruginosa (PA) by alveolar macrophages from patients with COPD. Sulforaphane treatment restored bacteria recognition and phagocytosis in alveolar macrophages from COPD patients. Furthermore, sulforaphane treatment enhanced pulmonary bacterial clearance by alveolar macrophages and reduced inflammation in wild-typemice but not in Nrf2-deficientmice exposed to cigarette smoke for 6 months. Gene expression and promoter analysis revealed that Nrf2 increased phagocytic ability of macrophages by direct transcriptional up-regulation of the scavenger receptor MARCO. Disruption of Nrf2 or MARCO abrogated sulforaphane-mediated bacterial phagocytosis by COPD alveolar macrophages. Our findings demonstrate the importance of Nrf2 and its downstream target MARCO in improving antibacterial defenses and provide a rationale for targeting this pathway, via pharmacological agents such as sulforaphane, to prevent exacerbations of COPD caused by bacterial infection. PMID:21490276

Induction of ovarian activity and ovulation in an induced ovulator, the maned wolf (Chrysocyon brachyurus), using GnRH agonist and recombinant LH.

PubMed

Johnson, Amy E M; Freeman, Elizabeth W; Colgin, Mark; McDonough, Caitlin; Songsasen, Nucharin

2014-07-01

Assisted reproductive techniques, such as ovarian manipulation and artificial insemination, are useful for enhancing genetic management of threatened wildlife maintained ex situ. In this study, we used noninvasive fecal hormone monitoring to investigate (1) the influence of pairing with a male on endocrine responses of female maned wolves (Chrysocyon brachyurus) to a GnRH agonist (deslorelin) and (2) the efficiency of recombinant LH (reLH) on ovulation induction in females housed alone. Deslorelin (2.1 mg Ovuplant) was given to females that were either paired with a male (n = 4) or housed alone (n = 7); the implant was removed 7 to 11 days postimplantation. Three of seven singleton females were injected with reLH (0.0375 mg) on the day of implant removal, whereas the remaining females (n = 4) did not receive the additional treatment. Fecal samples were collected 5 to 7 days/wk from all females starting 11 days prior to hormone insertion until at least 70 days post implant removal for a total of 11 hormone treatment cycles. Fecal estrogen and progestagen metabolites were extracted and analyzed by enzyme immunoassay. Evidence of ovulation, demonstrated by a surge of estrogen followed by a significant rise in progestagen, occurred in all paired females. Three of the four singleton females that did not receive reLH treatment exhibited no rise in progestagen after an estrogen surge. All singleton females treated with reLH exhibited a rise in fecal progestagen after injection, indicating ovulation. In conclusion, deslorelin is effective at inducing ovarian activity and ovulation in paired female maned wolves; however, exogenous reLH is needed to induce ovulation in females housed alone. The findings obtained from this study serve as a foundation for future application of artificial insemination to enhance genetic management of this threatened species ex situ. Published by Elsevier Inc.

Local and Regional Diversity Reveals Dispersal Limitation and Drift as Drivers for Groundwater Bacterial Communities from a Fractured Granite Formation

PubMed Central

Beaton, E. D.; Stevenson, Bradley S.; King-Sharp, Karen J.; Stamps, Blake W.; Nunn, Heather S.; Stuart, Marilyne

2016-01-01

Microorganisms found in terrestrial subsurface environments make up a large proportion of the Earth’s biomass. Biogeochemical cycles catalyzed by subsurface microbes have the potential to influence the speciation and transport of radionuclides managed in geological repositories. To gain insight on factors that constrain microbial processes within a formation with restricted groundwater flow we performed a meta-community analysis on groundwater collected from multiple discrete fractures underlying the Chalk River Laboratories site (located in Ontario, Canada). Bacterial taxa were numerically dominant in the groundwater. Although these were mainly uncultured, the closest cultivated representatives were from the phenotypically diverse Betaproteobacteria, Deltaproteobacteria, Bacteroidetes, Actinobacteria, Nitrospirae, and Firmicutes. Hundreds of taxa were identified but only a few were found in abundance (>1%) across all assemblages. The remainder of the taxa were low abundance. Within an ecological framework of selection, dispersal and drift, the local and regional diversity revealed fewer taxa within each assemblage relative to the meta-community, but the taxa that were present were more related than predicted by chance. The combination of dispersion at one phylogenetic depth and clustering at another phylogenetic depth suggest both niche (dispersion) and filtering (clustering) as drivers of local assembly. Distance decay of similarity reveals apparent biogeography of 1.5 km. Beta diversity revealed greater influence of selection at shallow sampling locations while the influences of dispersal limitation and randomness were greater at deeper sampling locations. Although selection has shaped each assemblage, the spatial scale of groundwater sampling favored detection of neutral processes over selective processes. Dispersal limitation between assemblages combined with local selection means the meta-community is subject to drift, and therefore, likely reflects the

Local and Regional Diversity Reveals Dispersal Limitation and Drift as Drivers for Groundwater Bacterial Communities from a Fractured Granite Formation.

PubMed

Beaton, E D; Stevenson, Bradley S; King-Sharp, Karen J; Stamps, Blake W; Nunn, Heather S; Stuart, Marilyne

2016-01-01

Microorganisms found in terrestrial subsurface environments make up a large proportion of the Earth's biomass. Biogeochemical cycles catalyzed by subsurface microbes have the potential to influence the speciation and transport of radionuclides managed in geological repositories. To gain insight on factors that constrain microbial processes within a formation with restricted groundwater flow we performed a meta-community analysis on groundwater collected from multiple discrete fractures underlying the Chalk River Laboratories site (located in Ontario, Canada). Bacterial taxa were numerically dominant in the groundwater. Although these were mainly uncultured, the closest cultivated representatives were from the phenotypically diverse Betaproteobacteria, Deltaproteobacteria, Bacteroidetes, Actinobacteria, Nitrospirae, and Firmicutes. Hundreds of taxa were identified but only a few were found in abundance (>1%) across all assemblages. The remainder of the taxa were low abundance. Within an ecological framework of selection, dispersal and drift, the local and regional diversity revealed fewer taxa within each assemblage relative to the meta-community, but the taxa that were present were more related than predicted by chance. The combination of dispersion at one phylogenetic depth and clustering at another phylogenetic depth suggest both niche (dispersion) and filtering (clustering) as drivers of local assembly. Distance decay of similarity reveals apparent biogeography of 1.5 km. Beta diversity revealed greater influence of selection at shallow sampling locations while the influences of dispersal limitation and randomness were greater at deeper sampling locations. Although selection has shaped each assemblage, the spatial scale of groundwater sampling favored detection of neutral processes over selective processes. Dispersal limitation between assemblages combined with local selection means the meta-community is subject to drift, and therefore, likely reflects the

Distinct Habitats Select Particular Bacterial Communities in Mangrove Sediments.

PubMed

Rocha, Lidianne L; Colares, Geórgia B; Nogueira, Vanessa L R; Paes, Fernanda A; Melo, Vânia M M

2016-01-01

We investigated the relationship among environmental variables, composition, and structure of bacterial communities in different habitats in a mangrove located nearby to an oil exploitation area, aiming to retrieve the natural pattern of bacterial communities in this ecosystem. The T-RFLP analysis showed a high diversity of bacterial populations and an increase in the bacterial richness from habitats closer to the sea and without vegetation (S1) to habitats covered by Avicennia schaueriana (S2) and Rhizophora mangle (S3). Environmental variables in S1 and S2 were more similar than in S3; however, when comparing the bacterial compositions, S2 and S3 shared more OTUs between them, suggesting that the presence of vegetation is an important factor in shaping these bacterial communities. In silico analyses of the fragments revealed a high diversity of the class Gammaproteobacteria in the 3 sites, although in general they presented quite different bacterial composition, which is probably shaped by the specificities of each habitat. This study shows that microhabitats inside of a mangrove ecosystem harbor diverse and distinct microbiota, reinforcing the need to conserve these ecosystems as a whole.

Distinct Habitats Select Particular Bacterial Communities in Mangrove Sediments

PubMed Central

Rocha, Lidianne L.; Colares, Geórgia B.; Nogueira, Vanessa L. R.; Paes, Fernanda A.; Melo, Vânia M. M.

2016-01-01

We investigated the relationship among environmental variables, composition, and structure of bacterial communities in different habitats in a mangrove located nearby to an oil exploitation area, aiming to retrieve the natural pattern of bacterial communities in this ecosystem. The T-RFLP analysis showed a high diversity of bacterial populations and an increase in the bacterial richness from habitats closer to the sea and without vegetation (S1) to habitats covered by Avicennia schaueriana (S2) and Rhizophora mangle (S3). Environmental variables in S1 and S2 were more similar than in S3; however, when comparing the bacterial compositions, S2 and S3 shared more OTUs between them, suggesting that the presence of vegetation is an important factor in shaping these bacterial communities. In silico analyses of the fragments revealed a high diversity of the class Gammaproteobacteria in the 3 sites, although in general they presented quite different bacterial composition, which is probably shaped by the specificities of each habitat. This study shows that microhabitats inside of a mangrove ecosystem harbor diverse and distinct microbiota, reinforcing the need to conserve these ecosystems as a whole. PMID:26989418

Fox-2 protein regulates the alternative splicing of scleroderma-associated lysyl hydroxylase 2 messenger RNA.

PubMed

Seth, Puneet; Yeowell, Heather N

2010-04-01

Scleroderma (systemic sclerosis [SSc]) is a complex connective tissue disorder characterized by hardening and thickening of the skin. One hallmark of scleroderma is excessive accumulation of collagen accompanied by increased levels of pyridinoline collagen crosslinks derived from hydroxylysine residues in the collagen telopeptide domains. Lysyl hydroxylase 2 (LH2), an important alternatively spliced enzyme in collagen biosynthesis, acts as a collagen telopeptide hydroxylase. Changes in the pattern of LH2 alternative splicing, favoring increased inclusion of the alternatively spliced LH2 exon 13A, thereby increasing the levels of the long transcript of LH2 (LH2[long]), are linked to scleroderma disease. This study was undertaken to examine the role played by RNA binding protein Fox-2 in regulating exon 13A inclusion, which leads to the generation of scleroderma-associated LH2(long) messenger RNA (mRNA). Phylogenetic sequence analysis of introns flanking exon 13A was performed. A tetracycline-inducible system in T-Rex 293 cells was used to induce Fox-2 protein, and endogenous LH2(long) mRNA was determined by reverse transcriptase-polymerase chain reaction. An LH2 minigene was designed, validated, and used in Fox-2 overexpression and mutagenesis experiments. Knockdown of Fox-2 was performed in mouse embryonic fibroblasts and in fibroblasts from SSc patients. Overexpression of Fox-2 enhanced the inclusion of exon 13A and increased the generation of LH2(long) mRNA, whereas knockdown of Fox-2 decreased LH2(long) transcripts. Mutational analysis of an LH2 minigene demonstrated that 2 of the 4 Fox binding motifs flanking LH2 exon 13A are required for inclusion of exon 13A. In early passage fibroblasts derived from patients with scleroderma, the knockdown of Fox-2 protein significantly decreased the endogenous levels of LH2(long) mRNA. Our findings indicate that Fox-2 plays an integral role in the regulation of LH2 splicing. Knockdown of Fox-2 and other methods to decrease