bluuebunny/crossref_metadata_2025 huggingface dataset:
Lectin binding on surfaces of Frankia strains
Authors: Chaboud Annie , Lalonde Maurice
Published: November 2009

As a prerequisite for the formation of symbiotic association the two partners must come in contact at their cell surfaces, where the phenomena of specificity and recognition are believed to take place. Therefore, in the case of actinorhizal symbioses, probing of Frankia cell surfaces was investigated with fluorescein-labelled lectins as specific markers for sugar residues. Eleven Frankia isolates grown in vitro and originating from Alnus and Elaeagnus host-plant specificity groups were tested with lectins of different carbohydrate-binding specificities. The N-acetylglucosamine and sialic acid binding lectin groups were able to bind to cell surfaces of both type-N and type-P strains of the Alnus group but not to any Frankia strains of the Elaeagnus group. Sugar residues recognized by these lectin groups on colonies of Frankia strains of the Alnus group were detected on hyphae, vesicles, and sporangia but not on mature spores. The present lectin binding study demonstrates that the use of lectins as bioprobes can be a valid tool in the awaited species definition in the genus Frankia.
The role of diffusion in oxygen protection of nitrogenase in nodules of Alnus rubra
Authors: Winship Lawrence J. , Tjepkema John D.
Published: November 2009

Endophyte respiration in actinorhizal nodules has two main functions: to provide ATP and reductant for nitrogenase and associated enzymes and to protect nitrogenase from inactivation by oxygen. Combined with a diffusion path which limits the flow of oxygen, the consumption of oxygen by respiration maintains a very low internal [Formula: see text]. We have used a continuous-flow root-nodule gas-exchange system to investigate the properties of such a diffusion path in intact, attached nodules of Alnus rubra infected with Frankia strain ArI3. When nodules were exposed to gas mixtures containing argon, oxygen, and acetylene, the resulting curves of ethylene production versus acetylene concentration showed diffusion-limited enzyme kinetics. Consequently, ethylene production at very low acetylene concentrations (<0.2% v/v) was used to characterize the diffusion path that both acetylene and oxygen must traverse to reach their active sites in the endophyte. The permeability of this path changed markedly with temperature and can account for the shape of the temperature response curve for total nitrogenase activity. Owing to the temperature-dependent barrier, energy production remains limited by oxygen diffusion, and nitrogenase can function over a wide temperature range at a relatively constant energy cost without inactivation by excess oxygen.
Uranium accumulation in the lichen Cladonia rangiferina. Part II. Toxic effects of cationic, neutral, and anionic forms of the uranyl ion
Authors: Boileau L. J. R. , Nieboer E. , Richardson D. H. S.
Published: November 2009

The toxicity of the uranyl ion to the lichen Cladonia rangiferina (L.) Wigg. was shown to be strongly dependent on chemical speciation. Photosynthetic measurements indicated that the anionic complex of oxalate [Formula: see text] was more toxic than the uncomplexed cation [Formula: see text]. No detrimental response could be assigned to the neutral phthalate complex (UO2L). Toxicity was also affected by the physiological condition of the lichen material. Samples exhibiting low photosynthetic levels typical for winter-collected material were damaged to a greater degree. Neither the cationic nor anionic species induced K+ loss from the lichen and the small release induced by the neutral species of the uranyl ion in phthalate buffer reflects a reduction in membrane integrity resulting from Ca2+ depletion. The effects of the uranyl ion and of the buffers used on Ca2+ displacement from lichen samples are discussed. Uranium uptake induced a reduction in total 14C fixation rates, a decrease in the proportion of radioactivity in the ethanol-soluble fraction, and an increase in the ethanol-insoluble fraction. These effects are ascribed to interference with bicarbonate transfer into the algal cell and the blocking of carbohydrate transport from the algal partner.
Petersenia palmariae n. sp. (Oomycetes): a pathogenic parasite of the red alga Palmaria mollis (Rhodophyceae)
Authors: Meer John P. van der , Pueschel Curt M.
Published: November 2009

Specimens of Palmaria mollis (Setchell and Gardner) van der Meer and Bird collected from Vancouver Island, Canada, were found to harbour a pathogenic fungal parasite. When infected fronds were put into culture, the algal thallus became completely covered with small white lesions. These were most concentrated in young tissue and soon killed the apices of the fronds. The parasite completed approximately one infection cycle per week at 10 °C. It died at temperatures near 15 °C, even though the host remained healthy at 20 °C. The parasite was identified as a species of Petersenia (Oomycetes). It most resembled P. lobata (H. E. Petersen) Sparrow but differed sufficiently in detail to consider it a new species, Petersenia palmariae. The new species does not infect Ceramium rubrum (Hudson) C. Agardh which serves as host for both P. lobata and P. pollagaster, the only other members of the genus known to parasitize marine algae. Nor does it infect Palmaria palmata (L.) O. Kuntze, a species related to the host on which it was discovered, which suggests Petersenia palmariae may be host specific.
Morphological and taxonomic relationships among branched, ligulate members of the genus Desmarestia (Phaeophyceae, Desmarestiales), with particular reference to South African D. firma
Authors: Anderson Robert James
Published: November 2009

An examination is made of the reproductive anatomy and the morphology of branched, ligulate members of the genus Desmarestia from worldwide localities. Entities from southern Africa, New Zealand, South America, Gough Island, northwestern America, and Europe show varying degrees of morphological overlap, but all possess sporangia similar in size and shape to, and scattered among, the vegetative cortical cells. Specimens from Signy Island (South Orkneys) have sporangia subtended by stalk cells, interspersed with sterile paraphyses, and arranged in a palisadelike sorus (Antarctic type). The taxonomic implications of these findings are discussed. The New Zealand and Gough entities are referred to D. ligulata (Stackhouse) Lamouroux and the name D. firma (C.Ag.) Skottsb. is retained for the southern African entity.
The reproductive biology of Hydrocharis morsus-ranae. II. Seed and seedling morphology
Authors: Scribailo Robin W. , Posluszny Usher
Published: November 2009

This study of seed and seedling morphology in the aquatic monocotyledon Hydrocharis morsus-ranae L. (Hydrocharitaceae) represents part of a continuing study of sexual reproduction in this species. Scanning electron microscope studies of the seeds showed them to have testas covered with hollow spiraliform tubercles. Germination occurs when the radicle and cotyledon of the embryo from the exalbuminous seed elongate, splitting the tuberculate testa. The buoyant embryo then rises to the surface with the first foliage leaves emerging from a highly modified cotyledonary sheath. This makes early growth in the seedling look strictly hypocotyledonary. Both the radicle and cotyledon discontinue growth by the two-leaf stage in the seedlings. The young seedlings undergo several growth phases. At first they look Lemna-like in habit and then, subsequently, very similar to germinating turions of the same species. Several methods are discussed to help distinguish between germinating turions and seedlings. During a subsequent field study of a H. morsus-ranae population, only two germinating seedlings were discovered. Several reasons for the absence of seedlings in this population are discussed.
Nitrogen absorption and assimilation in NaCl-resistant and NaCl-susceptible millet genotypes (Pennisetum americanum)
Authors: Bottacin Alessandra , Cacco Giovanni , Saccomani Massimo
Published: November 2009

Nitrogen absorption and assimilation were compared in salt-resistant and salt-susceptible genotypes of millet (Pennisetum americanum L. Leeke) in the absence of NaCl (control) and under saline conditions (300 mM NaCl). At 300 mM NaCl, Na+ and Cl− contents of leaves were lower in the resistant than in the susceptible genotypes and K+ content decreased with respect to the control in both genotypes. In the susceptible genotypes, the uptake of both [Formula: see text] and [Formula: see text] was inhibited by NaCl, while in the resistant genotypes only [Formula: see text] uptake was inhibited. The activities of several enzymes of nitrogen assimilation were also related to salinity tolerance: in vivo nitrate reductase and NADH- and NADPH-dependent glutamate dehydrogenase increased; in vitro nitrate reductase and the rate of [14C]leucine incorporation decreased. Only the glutamine pathway enzymes, glutamine synthetase and glutamate synthase, gave different responses to salinity in relation to the genotype: both enzyme activities were higher in the resistant and lower in the susceptible genotypes. These results suggest that the shift of nitrogen assimilation toward the glutamine route is the main feature of the salt adaptation in millet.
Breeding systems and genetic variation in Amsinckia spectabilis (Boraginaceae)
Authors: Ganders Fred R. , Denny Susan K. , Tsai David
Published: November 2009

Samples from 10 populations of Amsinckia spectabilis var. spectabilis and three populations of A. spectabilis var. microcarpa were analyzed for allelic variation at 17 allozyme loci using stareh gel electrophoresis. This species is a self-compatible annual which has heterostylous populations, homostylous populations, and mixed populations containing heterostylous and homostylous plants. Heterostylous populations had the highest outcrossing rates, homostylous populations the lowest, and mixed populations were intermediate in outcrossing rate. Outcrossing rate is highly correlated with the average stigma–anther separation in flowers in the populations. Genetic variability was highest in heterostylous populations, lowest in homostylous populations, and was intermediate in mixed populations, although one large homostylous population was as variable as were mixed populations. Genetic identities among populations were very high with the exception of the two northernmost, isolated homostylous populations which were fixed for rare alleles at some loci. In the rest of the populations, genetic identities were higher between populations of the same taxonomic variety than they were in intervarietal comparisons.
Host infection and flower formation by the parasite Tristerix aphyllus (Loranthaceae)
Authors: Mauseth James D. , Montenegro Gloria , Walckowiak Alan M.
Published: November 2009

Tristerix aphyllus is able to invade its host as follows. As a seed germinates, the tip of the radicle swells and attaches to the host, forming a haustorium. Slender multiseriate filaments are produced that can pass through the stomata and enter the host. Additionally, the haustorium forms a layer of cells that slide radially from the center of the haustorium. Because the cells adhere to the host surface, they tear the cuticle and epidermis away as they slide, thereby exposing inner layers of the host to invasion by filaments of cells produced by the haustorium. After invasion, the seed and embryo die and fall away, and T. aphyllus exists purely as an endophyte. To produce flowers, certain filaments of T. aphyllus, lying just below the host epidermis, proliferate forming nodules of callus. Within these nodules, up to 10 adventitious floral buds arise, either exogenously or endogenously. These have an apical meristem, a short axis, and three to six leaf primordia. By an unknown mechanism, the nodule is able to kill and break open the host hypodermis and epidermis; when this happens, one or several of the buds (which become dormant after formation) resume growth and emerge through the broken host epidermis.
Scanning electron microscopic observations of basidiospores in Pholiota and related genera
Authors: Farr David F.
Published: November 2009

Scanning electron microscopic observations of basidiospores are reported for 16 species of Pholiota, 3 species of Stropharia, 3 species of Hypholoma, and 1 species of Psilocybe. The surface of the spores varies from smooth to granulate or verrucate, to being covered with baculate, clavate, or echinulate elements or intricately ridged. Fresh spores fixed in glutaraldehyde exhibit a different ornamentation than spores of the same specimen fixed in Formalin – acetic acid – alcohol. The appearance of herbarium material rehydrated in water differs from that of fresh material fixed in glutaraldehyde or Formalin – acetic acid – alcohol. Differences in spore ornamentation between species were more apparent in material fixed in glutaraldehyde. The range of ornamentation types suggests that this character may have taxonomic value.
Late Wisconsin and Holocene vegetational history of the Upper Koyukuk region, Brooks Range, AK
Authors: Edwards Mary E. , Anderson Patricia M. , Garfinkel Harriet L. , Brubaker Linda B.
Published: November 2009

Three pollen diagrams provide information on late Wisconsin and Holocene vegetation history at high elevation and midelevations (1000 and 600 m) in the east-central Brooks Range. After the retreat of glacial ice and until about 12 000 years before present, the vegetation was a tundra, dominated by Salix, Cyperaceae, Gramineae, Artemisia, and other herbaceous taxa. However, because the early pollen spectra do not have close modern analogs, the detailed composition and ecology of this tundra cannot be inferred. Between ca. 12 000 and ca. 8 000 years before present, Betula nana–glandulosa was the dominant pollen producer at both elevations; a significant ericaceous component was present in the vegetation of the alpine sites, but not at the lower elevation site. During the period 10 500 – 8 500 years before present, Populus balsamifera and Juniperus were probably abundant at the lower site and may also have been present at the higher sites, where they are now absent. Picea glauca, Alnus spp., Picea mariana, and Betula papyrifera became established at the lower site between ca. 8500 and 6000 years before present. None of these species currently grows at the high sites, but their arrival at lower elevations is represented in the regional pollen rain at these sites. The arrival times of Picea glauca and Picea mariana in the study area are consistent with the hypothesis that P. glauca preceded P. mariana into the central Brooks Range.
Effect of Azospirillum spp. inoculation on root development and uptake in wheat (Triticum aestivum cv. Miriam) in hydroponic systems
Authors: Kapulnik Yoram , Gafny Ron , Okon Yaacov
Published: November 2009

Wheat (Triticum aestivum cv. Miriam) was grown in petri dishes and in vermiculite-filled pots. Inoculation with a mixture of Azospirillum brasilense strains Cd, Sp 7, and Cd-1, a local strain, significantly enhanced above noninoculatcd controls the root length and branching. In a hydroponic system containing [Formula: see text], the surface area of roots and the uptake of [Formula: see text] from the mineral solution during plant growth were increased by inoculation. However, no significant changes were obtained in the [Formula: see text] uptake – root surface area ratio. Heading and flowering occurred earlier in the inoculated plants as compared with the noninoculated plants. Total shoot and root weights, plant height, the number of fertile tillers, and grain yield were significantly increased by inoculation. The inoculated roots did not show any nitrogen fixation activity. It was concluded that under these experimental conditions, the benefits obtained in wheat inoculated with Azospirillum are mainly derived from an enhancement of root development and the amount of [Formula: see text] taken up by the roots.
THE HEISENBERG FAMILY FOR THE PRINCIPAL GRADING OF $U_q(\hat{\cal G})$
Authors: ZUEVSKY A.
Published: November 2009

We describe existence conditions and explicitly construct elements for a Heisenberg family in the principal grading of the quantized universal enveloping algebra [Formula: see text] of an affine Kac–Moody algebra [Formula: see text] in the Drinfeld formulation.
PROPERTIES OF Ta2O5 THIN FILMS DEPOSITED BY DC REACTIVE MAGNETRON SPUTTERING
Authors: ZHOU JICHENG , LUO DITIAN , LI YOUZHEN , LIU ZHENG
Published: November 2009

Ta 2 O 5 thin films were deposited at different oxygen flow ratio ( O 2/( O 2+Ar) = 10 ~ 80%) by DC reactive magnetron sputtering. Influence of oxygen flow ratio on depositing rate, surface characteristics, microstructure, and optical properties are discussed in this paper. With the increasing of oxygen, deposition rate decreases exponentially, the root mean square roughness and the maximum roughness decrease according to the atom force microscope images. XRD patterns indicate the as-deposited Ta 2 O 5 films are amorphous. Based on the envelop method, the samples' optical constants are calculated from the curve of transmission spectrum. The results indicate that refractive index n increases from 2.01 to 2.20 (λ = 500 nm ) for the oxygen flow ratio increases from 20% to 60%, the extinction coefficient k appears to decrease.
DFT STUDY ON POLYDIACETYLENES AND THEIR DERIVATIVES
Authors: HUANG BIN , CHEN XING , CAO ZEXING
Published: November 2009

Optimized geometries and vibrational frequencies of polydiacetylenes (PDAs) and their derivatives were studied by density functional calculations at the B3LYP/6-31G* level. The time-dependent density functional theory was used to determine their vertical transition energies and corresponding oscillator strengths. Calculations show that different side groups in these linear carbon chains can significantly modify their structural and electronic properties, whereas the effect of terminal substitution is negligible. Predicted equilibrium geometries indicate that the single, double, and triple bonds of PDAs and their derivatives are almost unchanged as the chain increases, showing a remarkable character of localized bond. The periodic boundary condition calculations reveal that the strongest adsorption for the infinite chain of PDA appears at 723 nm, and the HOMO → LUMO excitation is responsible for this strong electronic transition.
MOLECULAR DYNAMICS AND FREE ENERGY ANALYSES OF ERK2–PYRAZOLYLPYRROLE INHIBITORS INTERACTIONS: INSIGHT INTO STRUCTURE-BASED LIGAND DESIGN
Authors: ZHAN JIN-HUI , ZHAO XI , HUANG XU-RI , SUN CHIA-CHUNG
Published: November 2009

The extracellular signal-regulated protein kinase 2 (ERK2) is a pivotal member involving in Ras/Raf/MEK/ERK signal transduction pathway, acting as a central point where multiple signaling pathways coalesce to drive transcription. The pyrazolylpyrrole compounds as ATP competitive inhibitors of ERK2 can bind target with a special binding mode and have higher inhibitory potency than other ERK2-inhibitors. We investigated the interaction mode of ERK2-inhibitor using molecular dynamics simulation. The molecular mechanics Poisson–Boltzmann surface area approach is used to calculate the binding free energy of ERK2 with pyrazolylpyrrole inhibitors to analyze the factors of improving the affinity. The results indicated that the electrostatic interactions play the most important role in keeping the stabilization of ERK2-inhibitor. The structural analyses showed that the protein motions can be controlled by changing the structures of inhibitors; furthermore, the full use of available space in the binding site by improving the flexibilities of inhibitors and introducing hydrophobic groups can increase the inhibitory effect.
EXPLORING THE ROLE OFC–H… π INTERACTIONS ON THE STRUCTURAL STABILITY OF ANTIMICROBIAL PEPTIDES
Authors: RAMANATHAN K. , SETHUMADHAVAN RAO
Published: November 2009

A computational analysis on the C – H … π interactions in a group of 53 antimicrobial peptides was investigated. A total of 162 C – H … π interactions were observed. Side-chain to side-chain C – H … π interactions are the predominant type of interactions in antimicrobial peptides data set. There was an average of one significant C – H … π interaction for every 7 residues in the antimicrobial peptides investigated. Long-range C – H … π interactions are the predominant type of interactions. The secondary structure preference, solvent accessibility and stabilization centers of these of C – H … π interacting residues were estimated. It is likely that the C – H … π interactions contribute significantly to the overall stability of antimicrobial peptides. These interactions were observed after a molecular dynamics study on these set of antimicrobial peptides using CHARMM force field.
Voltage-dependent facilitation of Cx46 hemichannels
Authors: Retamal Mauricio A. , Yin ShengYong , Altenberg Guillermo A. , Reuss Luis
Published: November 2009

Gap junction channels are formed by two hemichannels in series (one from each neighboring cell), which are in turn connexin hexamers. Under normal conditions, hemichannels at the plasma membrane are mostly closed but can be opened by changes in membrane voltage, extracellular divalent ion concentration, phosphorylation, pH, and redox potential. Recently, interactions between channels have been found to modulate the activity of several ion channels, including gap junction channels. Here, we studied whether connexin46 (Cx46) hemichannels display such behavior. We studied the response of the Cx46 hemichannels expressed in Xenopus laevis oocytes to consecutive depolarization pulses. Hemichannels formed by wild-type Cx46 and a COOH-terminal domain truncation mutant (Cx46ΔCT) were activated by voltage pulses. When the hemichannels were depolarized repeatedly from −60 mV to +80 mV, the amplitude of the outward and tail currents increased progressively with successive pulses. This phenomenon (“current facilitation”) depended on the amplitude of the depolarization, reaching a maximum at approximately +60 mV in oocytes expressing Cx46, and on the interval between pulses, disappearing with intervals longer than about 20 s. The current facilitation was also present in oocytes expressing Cx46ΔCT, ruling out a primary role of this domain in the facilitation. Nominal removal of divalent cations from the extracellular side caused maximal current activation of Cx46 and Cx46ΔCT hemichannels and prevented facilitation. The results suggest that Cx46 hemichannels show a cooperative activation independent of their COOH-terminal domain.
Growth hormone-releasing hormone activates sleep regulatory neurons of the rat preoptic hypothalamus
Authors: Peterfi Zoltan , McGinty Dennis , Sarai Erzsebet , Szymusiak Ronald
Published: November 2009

We examined whether growth hormone-releasing hormone (GHRH) may promote non-rapid eye movement (NREM) sleep via activation of GABAergic neurons in the preoptic area. Male Sprague-Dawley rats were implanted with EEG, EMG electrodes and a unilateral intracerebroventricular cannula. Groups of rats received injections (3 μl icv) with gonadotropin-releasing hormone (GHRH) (0.1 nmol/100 g body wt) or equal volume of physiological saline at the onset of the dark period and were permitted spontaneous sleep for 90 min. Separate groups of rats were sleep deprived by gentle handling for 90 min, beginning at the time of GHRH or saline injection, at the onset of the dark period. Other groups of rats received intracerebroventricular octreotide (somatostatin analog OCT) injections, intracerebroventricular injection of one of two doses of competitive GHRH antagonist, or intracerebroventricular saline injection at light onset and were then permitted 90 min spontaneous sleep-waking. Rats were killed immediately after the 90-min sleep/wake monitoring period. Brain tissue was processed for immunohistochemistry for c-Fos protein and glutamic acid decarboxylase (GAD). Single c-Fos and dual Fos-GAD cell counts were determined in the median preoptic nucleus (MnPN), and in the core and the extended parts of the ventrolateral preoptic nucleus (cVLPO and exVLPO). Intracerebroventricular GHRH elicited a significant increase in NREM sleep amount. Double-labeled Fos+GAD cell counts were significantly elevated after GHRH injection in the MnPN and VLPO in both undisturbed and sleep-deprived groups. OCT and GHRH antagonist significantly decreased NREM sleep amount compared with control rats. OCT injection increased single c-Fos-labeled cell counts in the MnPN, but not in the VLPO. Double-labeled cell counts were significantly reduced after OCT and the high dose of GHRH antagonist injection in all areas examined. These findings identify GABAergic neurons in the MnPN and VLPO as potential targets of the sleep-regulatory actions of GHRH.
Renal NOS activity, expression, and localization in male and female spontaneously hypertensive rats
Authors: Sullivan Jennifer C. , Pardieck Jennifer L. , Hyndman Kelly A. , Pollock Jennifer S.
Published: November 2009

The goal of this study was to examine the status of the renal nitric oxide (NO) system by determining NO synthase (NOS) isoform activity and expression within the three regions of the kidney in 14-wk-old male and female spontaneously hypertensive rats (SHR). NOS activity, and NOS1 and NOS3 protein expressions and localization were comparable in the renal cortex and outer medulla of male and female SHR. In contrast, male SHR had significantly less NOS1 and NOS3 enzymatic activity (0 ± 5 and 53 ± 7 pmol·mg−1·30 min−1, respectively) compared with female SHR (37 ± 16 and 172 ± 40 pmol·mg−1·30 min−1, respectively). Lower levels of inner medullary NOS1 activity in male SHR were associated with less NOS1 protein expression [45 ± 7 relative densitometric units (RDU)] and fewer NOS1-positive cells in the renal inner medulla compared with female SHR (79 ± 12 RDU). Phosphorylation of NOS3 is an important determinant of NOS activity. Male SHR had significantly greater phosphorylation of NOS3 on threonine 495 in the renal cortex compared with females (0.25 ± 0.05 vs. 0.15 ± 0.06 RDU). NOS3 phosphorylation was comparable in males and females in the other regions of the kidney. cGMP levels were measured as an indirect index of NO production. cGMP levels were significantly lower in the renal cortex (0.08 ± 0.01 pmol/mg) and inner medulla (0.43 ± 0.02 pmol/mg) of male SHR compared with females (cortex: 0.14 ± 0.02 pmol/mg; inner medulla: 0.56 ± 0.02 pmol/mg). Our data suggest that the effect of the sex of the animal on NOS activity and expression is different in the three regions of the SHR kidney and supports the hypothesis that male SHR have lower NO bioavailability compared with females.
Sex differences in adaptive downregulation of pre-macula densa sodium transporters with ANG II infusion in mice
Authors: Tiwari Swasti , Li Lijun , Riazi Shahla , Halagappa Veerendra K. Madala , Ecelbarger Carolyn M.
Published: November 2009

An increase in blood pressure (BP) due to angiotensin II (ANG II) infusion or other means is associated with adaptive pressure natriuresis due to reduced sodium reabsorption primarily in proximal tubule (PT) and thick ascending limb (TAL). We tested the hypothesis that male and female mice would show differential response to ANG II infusion with regard to the regulation of the protein abundance of sodium transporters in the PT and TAL and that these responses would be modulated by aging. Young (∼3 mo) and old (∼21 mo) male and female mice were infused with ANG II at 800 ng·kg body wt−1·min−1by osmotic minipump for 7 days or received a sham operation. ANG II increased mean arterial pressure (MAP), measured by radiotelemetry, significantly more in male mice of both ages (increased ∼30–40 mmHg), compared with females (increased ∼15–25 mmHg). On day 1, MAP was also significantly increased in old mice, relative to young ( P = 0.01). ANG II infusion was associated with a significant decline in plasma testosterone (to <30% of control male) in male mice and rise in young female mice (to 478% of control female). No sex differences were found in the upregulation of the sodium hydrogen exchanger abundance on Western blots observed with ANG II infusion or the downregulation of the sodium phosphate cotransporter; however, aging did impact on some of these changes. Male mice (especially young) also had significantly reduced levels of the TAL bumetanide-sensitive Na-K-2Cl cotransporter (to 60% of male control), while young females showed an increase (to 126% of female control) with ANG II infusion. These sex differences do not support impaired pressure natriuresis in male mice, but might reflect a greater need and attempt to mount an appropriately BP-metered natriuretic response by additional downregulation of TAL sodium reabsorption.
Inhibitors of histone deacetylases suppress cisplatin-induced p53 activation and apoptosis in renal tubular cells
Authors: Dong Guie , Luo Jia , Kumar Vijay , Dong Zheng
Published: November 2009

Inhibitors of histone deacetylases, including suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA), are emerging anticancer agents. In the current study, we examined the cytoprotective effects of these agents. Cisplatin induced 40–50% apoptosis in rat kidney proximal tubular cells in 18 h, which was suppressed to 20–30% by 1–5 μM SAHA or 0.1 μM TSA. Consistently, SAHA partially prevented cisplatin-induced caspase activation. The cytoprotective effects of SAHA and TSA were associated with long-term cell survival. During cisplatin treatment, Bax translocated to mitochondria, leading to cytochrome c release. Both Bax translocation and cytochrome c release were ameliorated by SAHA. Mechanistically, SAHA inhibited and TSA delayed p53 phosphorylation, acetylation, and activation during cisplatin incubation. At the upstream signaling level, SAHA blocked cisplatin-induced phosphorylation of Chk2, a key DNA damage response kinase. Interestingly, in HCT116 colon cancer cells, SAHA suppressed cisplatin-induced p53 activation, but enhanced apoptosis. The results suggest that inhibitors of histone deacetylases can protect against cisplatin nephrotoxicity by attenuating DNA damage response and associated p53 activation.
A plate reader-based method for cell water permeability measurement
Authors: Fenton R. A. , Moeller H. B. , Nielsen S. , de Groot B. L. , Rützler M.
Published: November 2009

Cell volume and water permeability measurements in cultured mammalian cells are typically conducted under a light microscope. Many of the employed approaches are time consuming and not applicable to a study of confluent epithelial cell monolayers. We present here an adaptation of a calcein-quenching-based approach for a plate reader. A standard curve of fluorescence intensities at equilibrium has been recorded, following a shift from 285 mosmol/kgH2O to a series of altered extracellular osmolyte concentrations, ranging from final concentrations of 185 to 585 mosmol/kgH2O, by changing buffer d-mannitol concentrations. Similarly, according average cell volumes have been measured in suspension in a Coulter counter (particle-sizing device). Based on these measurements, we have derived an equation that facilitates the modeling of cell volume changes based on fluorescence intensity changes. We have utilized the method to study the role of a carboxyl-terminus aquaporin (AQP)-2 phosphorylation site, which is known to affect AQP2 membrane trafficking, in heterologous type I Madin-Darby canine kidney cells. We find that water permeability in cells expressing phosphorylation site mutants was in the following order: AQP2-S256D > AQP2 wild-type > AQP2-S256A. We propose that the method can be applied to study AQP function and more generally to study cell volume changes in adherent cell lines. Furthermore, it should be adaptable for AQP inhibitor screening in chemical compound libraries.
Modeling transport in the kidney: investigating function and dysfunction
Authors: Edwards Aurélie
Published: November 2009

Mathematical models of water and solute transport in the kidney have significantly expanded our understanding of renal function in both health and disease. This review describes recent theoretical developments and emphasizes the relevance of model findings to major unresolved questions and controversies. These include the fundamental processes by which urine is concentrated in the inner medulla, the ultrastructural basis of proteinuria, irregular flow oscillation patterns in spontaneously hypertensive rats, and the mechanisms underlying the hypotensive effects of thiazides. Macroscopic models of water, NaCl, and urea transport in populations of nephrons have served to test, confirm, or refute a number of hypotheses related to the urine concentrating mechanism. Other macroscopic models focus on the mechanisms, role, and irregularities of renal hemodynamic control and on the regulation of renal oxygenation. At the mesoscale, models of glomerular filtration have yielded significant insight into the ultrastructural basis underlying a number of disorders. At the cellular scale, models of epithelial solute transport and pericyte Ca2+signaling are being used to elucidate transport pathways and the effects of hormones and drugs. Areas where further theoretical progress is conditional on experimental advances are also identified.
Anticipatory Control of Motion-to-Force Transitions With the Fingertips Adapts Optimally to Task Difficulty
Authors: Cianchetti Flor A. , Valero-Cuevas Francisco J.
Published: November 2009

Moving our fingertips toward objects to produce well-directed forces immediately upon contact is fundamental to dexterous manipulation. This apparently simple motion-to-force transition in fact involves a time-critical, predictive switch in control strategy. Given that dexterous manipulation must accommodate multiple mechanical conditions, we investigated whether and how this transition adapts to task difficulty. Eight adults (19–39 yr) produced ramps of isometric vertical fingertip force against a rigid surface immediately following a tapping motion. By changing target surface friction and size, we defined an easier (sandpaper, 11 mm diam) versus a more difficult (polished steel, 5 mm diam) task. As in prior work, we assembled fine-wire electromyograms from all seven muscles of the index finger into a seven-dimensional vector defining the full muscle coordination pattern—and quantified its temporal evolution as its alignment with a reference coordination pattern vector for steady-state force production. As predicted by numerical optimizations to neuromuscular delays, our empirical and sigmoidal nonlinear regression analyses show that the coordination pattern transitions begin sooner for the more difficult tasks than for the easier tasks (∼120 ms, P < 0.02, and ∼115 ms, P < 0.015, respectively) and that the coordination pattern transition in alignment is well represented by a sigmoidal trend ( R^2 > 0.7 in most cases). Importantly, the force vector following contact had smaller directional error ( P < 0.02) for the more difficult task even though the transition in coordination pattern was less stereotypical and uniform than for the easier task. These adaptations of transition strategy to task difficulty are compatible with an optimization to counteract neuromuscular delays and noise to enable this fundamental element of dexterous manipulation.
Muscarinic Acetylcholine Receptor Modulation of Mu (μ) Opioid Receptors in Adult Rat Sphenopalatine Ganglion Neurons
Authors: Margas Wojciech , Mahmoud Saifeldin , Ruiz-Velasco Victor
Published: November 2009

The sphenopalatine ganglion (SPG) neurons represent the parasympathetic branch of the autonomic nervous system involved in controlling cerebral blood flow. In the present study, we examined the coupling mechanism between mu (μ) opioid receptors (MOR) and muscarinic acetylcholine receptors (mAChR) with Ca2+channels in acutely dissociated adult rat SPG neurons. Successful MOR activation was recorded in ∼40–45% of SPG neurons employing the whole cell variant of the patch-clamp technique. In addition, immunofluorescence assays indicated that MOR are not expressed in all SPG neurons while M2mAChR staining was evident in all neurons. The concentration-response relationships generated with morphine and [d-Ala2-N-Me-Phe4-Glycol5]-enkephalin (DAMGO) showed IC50values of 15.2 and 56.1 nM and maximal Ca2+current inhibition of 26.0 and 38.7%, respectively. Activation of MOR or M2mAChR with morphine or oxotremorine-methiodide (Oxo-M), respectively, resulted in voltage-dependent inhibition of Ca2+currents via coupling with Gαi/oprotein subunits. The acute prolonged exposure (10 min) of neurons to morphine or Oxo-M led to the homologous desensitization of MOR and M2mAChR, respectively. The prolonged stimulation of M2mAChR with Oxo-M resulted in heterologous desensitization of morphine-mediated Ca2+current inhibition, and was sensitive to the M2mAChR blocker methoctramine. On the other hand, when the neurons were exposed to morphine or DAMGO for 10 min, heterologous desensitization of M2mAChR was not observed. These results suggest that in rat SPG neurons activation of M2mAChR likely modulates opioid transmission in the brain vasculature to adequately maintain cerebral blood flow.
Split-Belt Treadmill Adaptation Shows Different Functional Networks for Fast and Slow Human Walking
Authors: Vasudevan Erin V. L. , Bastian Amy J.
Published: November 2009

New walking patterns can be learned over short time scales (i.e., adapted in minutes) using a split-belt treadmill that controls the speed of each leg independently. This leads to storage of a modified motor pattern that is expressed as an aftereffect in regular walking conditions and must be de-adapted to return to normal. Here we asked whether the nervous system adapts a general walking pattern that is used across many speeds or a specific pattern affecting only the two speeds experienced during split-belt training. In experiment 1, we tested three groups of healthy adult subjects walking at different split-belt speed combinations and then assessed aftereffects at a range of speeds. We found that aftereffects were largest at the slower speed that was used in split-belt training in all three groups, and it decayed gradually for all other speeds. Thus adaptation appeared to be more strongly linked to the slow walking speed. This result suggests a separation in the functional networks used for fast and slow walking. We tested this in experiment 2 by adapting walking to split belts and then determining how much fast regular walking washed out the slow aftereffect and vice versa. We found that 23–38% of the aftereffect remained regardless of which speed was washed out first. This demonstrates that there is only partial overlap in the functional networks coordinating different walking speeds. Taken together, our results suggest that there are some neural networks for controlling locomotion that are recruited specifically for fast versus slow walking in humans, similar to recent findings in other vertebrates.
Conditional Selection of Contra- and Ipsilateral Forelimb Movements by the Dorsal Premotor Cortex in Monkeys
Authors: Kurata Kiyoshi
Published: November 2009

It has been suggested that the dorsal premotor cortex (PMd) may contribute to conditional motor behavior. Thus when a selection is instructed by arbitrary conditional cues, it is possible that the unilateral PMd affects behavior, regardless of which arm, contra- or ipsilateral, is to be used. We examined this possibility by recording neuronal activity and injecting muscimol into the caudal PMd (PMdc) of monkeys while they were performing a reaching task toward visuospatial targets with either the right or left arm, as instructed by low-frequency or high-frequency tone signals. Following the injection of a small amount of muscimol (1 μL; 5 μg/μL) into the unilateral PMdc, monkeys exhibited two major deficits in behavioral performance: 1) erroneous selection of the arm not indicated by the instruction (selection errors) and 2) no movement initiation in response to a visuospatial target cue serving as a trigger signal for reaching within the reaction time limit (movement initiation errors). Errors were observed following unilateral muscimol injection into both right and left PMdc, although selection errors occurred with significantly greater frequency in the arm contralateral to the injection site. By contrast, movement initiation errors were more commonly observed in left-arm trials, regardless of whether the right or left PMdc was inactivated. Notably, errors rarely occurred following a ventral PM muscimol injection. These results suggest that the left and right PMdc cooperate to transform conditional sensory cues into appropriate motor output and can affect both contra- and ipsilateral body movement.
Conference Report: Seventh Annual AACR International Conference on Frontiers in Cancer Prevention Research
Authors: Brown Powel H. , Viner Jaye L. , Brewster Abenaa , Heckman Carolyn J. , Hursting Stephen , Johnson Karen , Mao Jenny T.
Published: November 2009

In November, 2008 the AACR held the Seventh Annual Frontiers in Cancer Prevention Research meeting in Washington, DC. At this meeting, a wide range of cutting-edge cancer prevention research was presented. This summary highlights some of the most impactful presentations with a focus on the interaction between inflammation, infections, the immune system, and tumor microenvironment in promoting cancer. Several of these presentations described targeting host-tumor interactions as a means for cancer prevention. As discussed below, this meeting continues to represent all phases of cancer prevention research including epidemiologic studies, behavioral and lifestyle interventions, carcinogenesis research, preclinical studies testing novel preventive interventions, and the results of early- and late-phase cancer prevention trials. Major advances presented at the 2008 meeting included studies showing that immune cells can be either protumorigenic or antitumorigenic, efforts to develop more comprehensive human papillomavirus vaccines to more effectively prevent cervical cancer and other human papillomavirus–related cancers, controversial studies of vitamin D and cancer risk, and studies of single-nucleotide polymorphisms to better assess cancer risk. These and the other presentations at this meeting continue to provide strong support for the concept that cancer will be most effectively controlled by applying modern cancer prevention strategies
Haggai and Ezekiel: The Complicated Relations between the Two Prophets
Authors: Kasher Rimon
Published: November 2009

The issue of a possible link between Haggai and Ezekiel (the prophets and the books) was raised in the recent years by several scholars. Among them are P. D. Hanson (1975), C. Stuhlmueller (1988), A. Laato (1992), and S. S. Tuell (2003). In this article we will examine some of the main arguments. It is our conclusion, based on a careful examination of the arguments, that only a few are valid. Yet we can show that both Haggai and Ezekiel share some prominent components of their world views. Both seem to belong to a millennial movement (based on a anthropological definition); both based their concepts upon theocentricity, and both deal seriously with the question of God's status. Their solutions are however quite different, due to their own experience and the difference in political and social situations.
Validation of Precipitable Water Vapor within the NCEP/DOE Reanalysis Using Global GPS Observations from One Decade
Authors: Vey Sibylle , Dietrich Reinhard , Rülke Axel , Fritsche Mathias , Steigenberger Peter , Rothacher Markus
Published: November 2009

In contrast to previous studies validating numerical weather prediction (NWP) models using observations from the global positioning system (GPS), this paper focuses on the validation of seasonal and interannual variations in the water vapor. The main advantage of the performed validation is the independence of the GPS water vapor estimates compared to studies using water vapor datasets from radiosondes or satellite microwave radiometers that are already assimilated into the NWP models. Tropospheric parameters from a GPS reanalysis carried out in a common project of the Technical Universities in Munich and Dresden were converted into precipitable water (PW) using surface pressure observations from the WMO and mean atmospheric temperature data from ECMWF. PW time series were generated for 141 globally distributed GPS sites covering the time period from the beginning of 1994 to the end of 2004. The GPS-derived PW time series were carefully examined for their homogeneity. The validation of the NWP model from NCEP shows that the differences between the modeled and observed PW values are time dependent. In addition to establishing a long-term mean, this study also validates the seasonal cycle and interannual variations in the PW. Over Europe and large parts of North America the seasonal cycle and the interannual variations in the PW from GPS and NCEP agree very well. The results reveal a submillimeter accuracy of the GPS-derived PW anomalies. In the regions mentioned above, NCEP provides a highly accurate database for studies of long-term changes in the atmospheric water vapor. However, in the Southern Hemisphere large differences in the seasonal signals and in the PW anomalies were found between GPS and NCEP. The seasonal signal of the PW is underestimated by NCEP in the tropics and in Antarctica by up to 40% and 25%, respectively. Climate change studies based on water vapor data from NCEP should consider the large uncertainties in the analysis when interpreting these data, especially in the tropics.
The Influence of the Basic State on the Northern Hemisphere Circulation Response to Climate Change
Authors: Sigmond Michael , Scinocca John F.
Published: November 2009

Employing a comprehensive atmospheric general circulation model, the authors have shown in a previous study that the time-mean Northern Hemisphere (NH) winter circulation response to a CO2 doubling perturbation depends significantly on parameterized orographic gravity wave drag (OGWD) parameter settings, which are essentially related to the strength of OGWD. A possible implication is that aspects of the greenhouse gas–induced circulation response could depend directly on the formulation and internal parameters settings of the OGWD scheme. Such a result would further heighten the importance of OGWD parameterizations for climate studies and have far-reaching implications for modeled projections of future climate change.

In this study the causal relationship between OGWD and changes in time-mean NH wintertime circulation response to CO2 doubling is investigated. This is accomplished by introducing a methodology that allows one to hold the OGWD forcing fixed to its 1 × CO2 value when CO2 is doubled. Employing this methodology for perturbation experiments with different strengths of OGWD, the authors find that the changes in OGWD forcing due to CO2 doubling have essentially no impact on the time-mean zonal-mean zonal wind response. The primary conclusion is that the OGWD influence is limited to its impact on the 1 × CO2 basic-state climatology, which defines the propagation characteristics of resolved waves. Different strengths of OGWD result in control basic states with different refractive properties for the resolved waves. It is shown that the action of resolved waves, as well as their sensitivity to such differences in the control climatology, explains essentially all of the NH wintertime circulation sensitivity identified here and in a previous study. Implications for climate change projections and climate-model development are discussed.