bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial community production, respiration, and structure of the microbial food web of an ecosystem in the northeastern Atlantic Ocean
Authors: Maixandeau Anne , Lefèvre Dominique , Karayanni Hera , Christaki Urania , Van Wambeke France , Thyssen Melilotus , Denis Michel , Fernández Camila I. , Uitz Julia , Leblanc Karine , Quéguiner Bernard
Published: July 2005

Gross community production (GCP), dark community respiration (DCR), and the biomass of the different size classes of organisms in the microbial community were measured in the northeastern Atlantic basin as part of the Programme Océan Multidisciplinaire Méso Echelle (POMME) project. The field experiment was conducted during three seasons (winter, spring, and late summer–fall) in 2001. Samples were collected from four different mesoscale structures within the upper 100 m. GCP rates increased from winter (101 ± 24 mmol O2 m−2 d−1) to spring (153 ± 27 mmol O2 m−2 d−1) and then decreased from spring to late summer (44 ± 18 mmol O2 m−2 d−1). DCR rates increased from winter (−47 ± 18 mmol O2 m−2 d−1) to spring (−97 ± 7 mmol O2 m−2 d−1) and then decreased from spring to late summer (50 ± 7 mmol O2 m−2 d−1). The onset of stratification depended on latitude as well as on the presence of mesoscale structures (eddies), and this largely contributed to the variability of GCP. The trophic status of the POMME area was defined as net autotrophic, with a mean annual net community production rate of +38 ± 18 mmol O2 m−2 d−1, exhibiting a seasonal variation from +2 ± 20 mmol O2 m−2 d−1 to +57 ± 20 mmol O2 m−2 d−1. This study highlights that small organisms (picoautotrophs, nanoautotrophs, and bacteria) are the main organisms contributing to biological fluxes throughout the year and that episodic blooms of microphytoplankton are related to mesoscale structures.
A synthesis of the POMME physical data set: One year monitoring of the upper layer
Authors: Gaillard F. , Mercier H. , Kermabon C.
Published: July 2005

The Programme Océan Multidisciplinaire Méso Echelle (POMME) experiment was designed to describe and quantify the role of mesoscale processes in the subduction of mode waters in the northeast Atlantic. During 1 year (September 2000–October 2001), in situ measurements were conducted over a 8° square area centered on 18°W, 42°N. We present the synthesis of the physical data set collected during this experiment. To improve time and space coverages, these measurements are combined with satellite information from sea surface temperature and altimetry. Daily fields of temperature, salinity, and stream function are produced over a seasonal cycle with a simplified Kalman filter. We analyze the annual cycle of the upper layer. The 1 year mean circulation in the upper 400 m resembles the scheme proposed by Paillet and Mercier (1997). The meridional component of the flow carries cold water southward, thus contributing to cool the POMME area. The annual mean heat budget shows that this advection by the mean current nearly balances the warming by the surface heat fluxes. The mixed layer maximum depth is reached in March. It increases, in zonal averages, from 100 m south of 38°N to more than 270 m north of 45°N and, remarkably, is shaped by the mesoscale. The subpolar mode water formed in the north of the POMME area has a lower density (26.8–27.0) than the mode water formed in the years 1988–1990 that Paillet and Arhan (1996) found in the density range (27.0–27.1). This mode water is continuously advected southward across the 42°N latitude, leading to an annual mean transport of 1.4 106 m3 s−1.
Detection of faceted crystals in deep convective clouds via the antisolar peak
Authors: Sherwood Steven C.
Published: July 2005

It is shown that an antisolar peak can clearly be detected in backscattered near‐infrared reflectances from deep convective cloud tops. This peak should be caused only by regularly faceted ice crystals, primarily columns and plates, rather than rimed or irregular particles. Using 13 years of AVHRR (advanced very high resolution radiometer) data, the average peak stands 22% above the background for sampled clouds having brightness temperatures below 220 K; the implied mean contribution of pristine crystals to total ice surface area, based on a published model, is 13 ± 5%. Local estimates of this percentage agree roughly with available field data. The distribution of peak strength is positively skewed, suggesting that a few deep cumuli may be rich in regular particles while a majority contain even less than the 13% mean. The antisolar peak varies geographically, with largest mean values over the central Atlantic and Pacific ITCZs, and smallest values over the Caribbean/American region during summer. Curiously, there is no significant land‐ocean contrast in the antisolar peak, even though MODIS (Moderate Resolution Imaging Spectroradiometer) data indicate a strong land‐ocean contrast in cumulus glaciation temperature, so it does not appear that supercooled water amounts at lower levels regulate the habit distribution observed at cloud top in any straightforward way. Variations in the antisolar peak may be significant for backscatter lidar retrievals of cloud extinction.
Solar cycle modulation of the Southern Annular Mode
Authors: Kuroda Yuhji , Kodera Kunihiko
Published: July 2005

The effect of the 11‐year solar cycle modulation on the Southern Annular Mode (SAM) in the Southern Hemisphere is examined through analysis of observational data from 1968 to 2001. It is found that the year‐to‐year variability of the October–November mean SAM differs significantly according to the solar activity. In high solar activity years, the SAM signal extends to the upper stratosphere during October to December and activity in the troposphere lasts until autumn, whereas in low solar activity years, the SAM signal is confined almost inside the troposphere from October to December and it disappears by January. This situation is very similar to that observed for the modulation of the winter mean North Atlantic Oscillation in the Northern Hemisphere. A possible mechanism of solar cycle modulation of the SAM is also discussed.
On the significance of atmospheric CO2 growth rate anomalies in 2002–2003
Authors: Jones Chris D. , Cox Peter M.
Published: July 2005

We examine the facts behind the growth rate of atmospheric CO2 in 2002 and 2003. Observations show consecutive increases of greater than 2 parts per million (ppmv) per year for the first time on the Mauna Loa record (which extends back to 1958). We use a statistical regression to show that increasing anthropogenic emissions and El Niño activity are able to account for variations in the CO2 growth rate at Mauna Loa, aside from the anomalously low growth rates of 1992 and 1993 following the Pinatubo volcanic eruption, and the anomalously high growth rate of 2003. Increased forest fires in the northern hemisphere, consistent with remote‐sensing and carbon monoxide measurements, seem likely to have contributed significantly to the 2003 anomaly. We hypothesise that the hot and dry Eurasian summer of 2003 led to an increase in forest fire emissions from Siberia, and may also have directly suppressed land‐carbon uptake. Insofar as the 2003 Eurasian summer may have been a symptom of anthropogenic climate change, it is possible that the 2003 CO2 growth rate anomaly is the first evidence of a positive climate‐carbon cycle feedback.
Estimating the seaward extent of sea breeze from QuikSCAT scatterometry
Authors: Aparna M. , Shetye S. R. , Shankar D. , Shenoi S. S. C. , Mehra P. , Desai R. G. P.
Published: July 2005

We present an objective method for quantifying the seaward extent of the sea breeze. The underlying assumption is that the offshore decay in the strength of the sea breeze results in an offshore decay of the vector correlation between the wind vectors near and away from the coast. The degradation in the vector correlation coefficient is used to estimate the seaward extent of the sea breeze using QuikSCAT data.
TRMM observations of the global relationship between ice water content and lightning
Authors: Petersen Walter A. , Christian Hugh J. , Rutledge Steven A.
Published: July 2005

This study uses TRMM lightning and radar observations to study the fundamental relationship between precipitation ice mass and lightning flash density. The results indicate that the physical assumptions of precipitation‐based charging and mixed phase precipitation development are robust and that on a global scale, the relationship between precipitation ice water path and lightning flash density is relatively invariant between land, ocean and coastal regimes. Hence lightning data may be a useful variable for inclusion in combined space borne algorithms designed to retrieve ice water content.
Novel polyisoprenyl phosphates block phospholipase D and human neutrophil activation in vitro and murine peritoneal inflammation in vivo
Authors: Levy Bruce D , Hickey Lorraine , Morris Andrew J , Larvie Mykol , Keledjian Raquel , Petasis Nicos A , Bannenberg Gerard , Serhan Charles N
Published: July 2005

Leukocyte production of reactive oxygen species (ROS) is an essential component of the antimicrobial armament mounted during host defense, but when released to the extracellular milieu ROS can also injure host tissues and provoke inflammation. Polyisoprenyl phosphates (PIPPs) are constituents of human leukocyte membranes that regulate pivotal intracellular enzymes, such as phospholipase D (PLD). We prepared new PIPP mimetics and studied their impact in vivo on leukocyte activation, including ROS generation, in acute inflammation.

In a stereospecific and concentration‐dependent manner, the PIPP mimetics directly regulated Streptomyces chromofuscus phospholipase D (sPLD) action. The IC50 for a (Z)‐isomer of endogenous presqualene diphosphate (PSDP) was 100 nM.

Structure–activity relationships were also determined for PIPP mimetic inhibition of recombinant human PLD1b, a prominent isoform in human leukocytes. The PIPP mimetic rank order for PLD1b inhibition differed from sPLD, although the (Z)‐PSDP isomer remained the most potent PIPP mimetic for inhibition of both enzymes. Truncation of PLD1b to its catalytic core uncovered potential regulatory roles for both PSDP's isoprenoid and diphosphate moieties.

The (Z)‐PSDP isomer reduced ROS production by activated human leukocytes and decreased murine neutrophil accumulation (65.6%) and ROS production (38.5%) in vivo during zymosan A‐initiated peritonitis. When administered intraperitoneally 2 h after zymosan A, the (Z)‐PSDP isomer decreased in vivo neutrophil accumulation (72.5%) and ROS generation (74.4%) 6 h later in peritoneal exudates.

Together, these results provide new means to protect and control unchecked inflammatory responses that characterize many human diseases.

British Journal of Pharmacology (2005) 146, 344–351. doi:10.1038/sj.bjp.0706338
Tight junction: a co‐ordinator of cell signalling and membrane trafficking
Authors: Köhler Katja , Zahraoui Ahmed
Published: July 2005

Increasing evidence indicates that the tight junction plays a role in membrane transport. Various signalling and trafficking molecules localize to the sites of cell—cell junctions in epithelial cells, including Rab proteins, a family of small GTPases that regulate different steps of vesicular transport along the endocytic and exocytic pathways. We have recently shown that Rab13 controls protein kinase A activity, demonstrating a clear biochemical and functional link between Rab13 and protein kinase A signalling during tight junction assembly in epithelial cells. The present article focuses on how protein kinase A signalling and protein trafficking events could be integrated at tight junctions in epithelial cells.
Toll-like receptors and chronic lung disease
Authors: Chaudhuri Nazia , Dower Steven K. , Whyte Moira K. B. , Sabroe Ian
Published: July 2005

TLRs (Toll-like receptors) comprise a family of proteins whose function is principally to facilitate the detection of, and response to, pathogens. Protozoa, helminths, viruses, bacteria and fungi can all activate TLR signalling, and these signals have important roles in the activation of host defence. TLRs may also respond to products of tissue damage, providing them with roles in infective and sterile inflammation. Their role as detectors of pathogens and pathogen-associated molecules provides molecular mechanisms to underpin the observations leading to the hygiene hypothesis. Targeting of TLR signalling has implications in the control of infection, vaccine design, desensitization to allergens and down-regulation of inflammation. This review will explore TLR history, molecular signalling and the potential roles of TLRs in chronic lung disease.
Ion association dynamics in aqueous solutions of sulfate salts as studied by Raman band shape analysis
Authors: Watanabe Daisuke , Hamaguchi Hiro-o
Published: July 2005

A new perspective is shown on the interaction between the sulfate ion and its counter cation in aqueous solutions. We propose the dynamic exchange model of ion association instead of the conventional static equilibrium model. The concentration dependence of the Raman band shape of the totally symmetric (a1) SO stretch mode of the sulfate ion is investigated systematically for four sulfate ions, MgSO4, (NH4)2SO4, K2SO4, and Li2SO4. The concentration dependence of the a1 Raman band shape in the MgSO4 system is successfully reproduced by the analysis based on the dynamic exchange model. As a result, quantitative information about the extremely dynamic nature of the ion association has been obtained: the mean time between associations is a few picoseconds and the mean lifetime of association is several hundred femtoseconds.
Simulations of one- and two-electron systems by Bead-Fourier path integral molecular dynamics
Authors: Ivanov Sergei D. , Lyubartsev Alexander P.
Published: July 2005

The Bead-Fourier path integral molecular dynamics technique introduced earlier [S. D. Ivanov, A. P. Lyubartsev, and A. Laaksonen, Phys. Rev. E 67 066710 (2003)] is applied for simulation of electrons in the simplest molecules: molecular hydrogen, helium atom, and their ions. Special attention is paid to the correct description of electrons in the core region of a nucleus. In an attempt to smooth the Coulomb potential at small distances, a recipe is suggested. The simulation results are in excellent agreement with the analytical solution for the “harmonic helium atom”, as well as with the vibrational potential of the H2 molecule and He ionization energies. It is demonstrated, that the Bead-Fourier path integral molecular dynamics technique is able to provide the accuracy required for the description of electron structure and chemical bonds in cases when electron exchange effects need not be taken into account.
Lanthanum silicate gate dielectric stacks with subnanometer equivalent oxide thickness utilizing an interfacial silica consumption reaction
Authors: Lichtenwalner Daniel J. , Jur Jesse S. , Kingon Angus I. , Agustin Melody P. , Yang Yan , Stemmer Susanne , Goncharova Lyudmila V. , Gustafsson Torgny , Garfunkel Eric
Published: July 2005

A silicate reaction between lanthana and silica layers has been utilized to eliminate interfacial silica in metal-insulator-semiconductor devices and to obtain devices with very low equivalent oxide thickness (EOT). This provides a simple process route to interface elimination, while producing a silicate dielectric with a higher temperature stability of the amorphous phase. The La2O3 layers in this study are deposited by reactive evaporation on (001) Si covered by a ∼0.8–1.0-nm-thick SiO2 chemical oxide, and are capped in situ with a Ta gate, followed by a reaction anneal, which lowers the EOT from greater than 1.5 nm for the as-deposited bilayer stack to as low as 0.5 nm. Electron energy-loss spectroscopy and medium-energy ion scattering are used to show that a temperature of 400 °C is sufficient for the formation of the silicate gate dielectric. Gate leakage currents as low as 0.06A∕cm2 are obtained for stacks having an EOT of 0.63 nm, orders of magnitude below that of SiO2 having the same EOT value. Electrical breakdown is observed at applied fields above 16MV∕cm.
Effects of nitrogen, oxygen, and moisture on the electron transport in tris(8-hydroxyquinoline) aluminum
Authors: Fong H. H. , So S. K.
Published: July 2005

The effects of nitrogen, oxygen, and moisture on the electron mobilities of tris(8-hydroxyquinoline) aluminum (Alq3) have been examined by time-of-flight (TOF) technique at room temperature under an applied electric-field range of 0.3–1MV∕cm. Our results suggest that both oxygen and water molecules can impede electron conduction in Alq3. Detailed analysis suggests that water molecules induce electron traps even at very low dosages. Oxygen interacts with Alq3 at high dosages and results in highly dispersive TOF signals. Moisture appears to be more detrimental than oxygen in hindering electron transport in Alq3.
Nitrogen effects on generation and velocity of dislocations in Czochralski-grown silicon
Authors: Yonenaga I.
Published: July 2005

The dynamic properties of individual dislocations in nitrogen (N)-doped Czochralski-grown Si crystals with concentrations up to 6×1015cm−3 were investigated at temperatures of 650–950°C using the etch pit technique and compared with such characteristics of N-free Si crystals. The velocity of dislocations in motion in N-doped crystals was revealed to be unaffected by N doping. It was found that the generation of dislocations from a surface scratch was suppressed in N-doped Si and that the critical stress for dislocation generation increased with N concentration, which is interpreted as being due to dislocation immobilization caused by impurity segregation. N doping is concluded to be effective in the promotion of precipitation of oxygen impurity resulting in immobilization of dislocations.
Otolith science entering the 21st century
Authors: Campana Steven E.
Published: July 2005

A review of 862 otolith-oriented papers published since the time of the 1998 Otolith Symposium in Bergen, Norway suggests that there has been a change in research emphasis compared to earlier years. Although close to 40% of the papers could be classifed as ‘annual age and growth’ studies, the remaining papers were roughly equally divided between studies of otolith microstructure, otolith chemistry and non-ageing applications. A more detailed breakdown of subject areas identified 15 diverse areas of specialisation, including age determination, larval fish ecology, population dynamics, species identification, tracer applications and environmental reconstructions. For each of the 15 subject areas, examples of representative studies published in the last 6 years were presented, with emphasis on the major developments and highlights. Among the challenges for the future awaiting resolution, the development of novel methods for validating the ages of deepsea fishes, the development of a physiologically-based otolith growth model, and the identification of the limits (if any) of ageing very old fish are among the most pressing.
Tracking continental habitat shifts of eels using otolith Sr/Ca ratios: validation and application to the coastal, estuarine and riverine eels of the Gironde - Garonne - Dordogne watershed
Authors: Daverat F. , Tomas J. , Lahaye M. , Palmer M. , Elie P.
Published: July 2005

To enable a relevant interpretation of otolith strontium : calcium (Sr/Ca) variations in terms of habitat shifts of eels, the Sr/Ca-salinity relationship in eel otoliths was validated. Downstream and upstream migrations of young eels were reproduced in the laboratory by transferring groups of fish every 2 months between aquaria filled with water coming from the Dordogne river (salinity = 0), the upper Gironde estuary (salinity = 5), the lower Gironde estuary (salinity = 25) and the coast (salinity = 30), which represented the salinity gradient observed in the Gironde–Garonne–Dordogne watershed. Ontogenetic changes in otolith Sr/Ca were assessed in two groups of control fish that were kept in one of either two constant salinities (fresh water or seawater). X-ray electron microprobe (wavelength dispersive spectrometry, WDS) analyses of Sr/Ca ratios in the otoliths showed that the change of aquarium was recorded as a Sr/Ca increase (downstream migration) or a Sr/Ca decrease (upstream migration). No ontogenetic effect was detected in otoliths of control fish outside glass eel marks in either group of fish. The electron microprobe (WDS) analysis of the Sr/Ca life (transected in several otoliths of eels caught in the Gironde–Garonne–Dordogne watershed) showed that some of them were migrant eels that had experienced one major habitat shift during their continental life.
A new method for robust feature extraction of otolith growth marks using fingerprint recognition methods
Authors: Palmer M. , Álvarez A. , Tomás J. , Morales-Nin B.
Published: July 2005

Individual and population age structures constitute essential knowledge for proper management of commercial fisheries. Despite the important advances made in age determination using otolith growth structures, there is still a need to improve both precision and accuracy. The problem of increasing precision in age estimations has been addressed via increasing automation in the identification of growth marks. However, approaches based on otolith size, weight, perimeter, and related measurements (including contour analysis) have moderate success in age prediction. Likewise, early attempts of image analysis have reported poor results, both in cases of 1D (grey-intensity profiles) or 2D images. Recent developments in image analysis have broken this trend, and fully automatic techniques could be an alternative for routine ageing in the near future. Here, we propose a new method for 2D feature extraction that provides robust numerical descriptors of the growth structures of otoliths.
Quality issues in the use of otoliths for fish age estimation
Authors: Morison A. K. , Burnett J. , McCurdy W. J. , Moksness E.
Published: July 2005

Quality issues in fish age estimation, which historically have focused mainly on inadequacies in the validation process, are increasingly directed at ways to measure and control the errors or inconsistencies in the application of established and validated methods. The process of age estimation, as undertaken by human operators, involves a complex mix of pattern recognition and interpretation based on knowledge and experience. It is best characterised as a skill rather than an art. Such an approach promotes the use of well-recognised techniques designed to maintain and enhance skills that also assist in maintaining standards. The results of a questionnaire completed by representatives of over 50 ageing laboratories worldwide were used to assess current quality assurance and quality control practices. Results indicate a great diversity in attention to, and no clear consensus on desirable standards for, quality issues, including staff training, use of reference sets, reading protocols, and post-reading analyses. This is considered more likely to reflect variation in awareness of the importance of quality issues than variation in the need for quality assurance and quality control measures. Greater attention to a range of quality control processes is urged, particularly the more regular use of reference sets.
Formation of morphologically similar globular aggregates from diverse aggregation-prone proteins in mammalian cells
Authors: Mukai Hideyuki , Isagawa Takayuki , Goyama Emiko , Tanaka Shuhei , Bence Neil F. , Tamura Atsuo , Ono Yoshitaka , Kopito Ron R.
Published: July 2005

Huntington's disease is a progressive neurodegenerative disorder caused by a polyglutamine repeat expansion in the first exon of the huntingtin (Htt) protein. N-terminal Htt peptides with polyglutamine tracts in the pathological range (51–122 glutamines) form high-molecular-weight protein aggregates with fibrillar morphology
in vitro
, and they form discrete inclusion bodies in a cell-culture model. However, in some studies, formation of discrete Htt inclusions does not correlate well with cell death. We coexpressed N-terminal Htt fragments containing 91 glutamines fused to different affinity tags in HEK293 cells, and we isolated small aggregates by double sequential-affinity chromatography to assure the isolation of multimeric molecules. Transmission electron microscopy and atomic force microscopy revealed the isolated aggregates as globules or clusters of globules 4–50 nm in diameter without any detectable fibrillar species. Because small nonfibrillar oligomers, not mature fibrils, recently have been suggested to be the principal cytotoxic species in neurodegenerative disease, these Htt globular aggregates formed in cells may represent the pathogenic form of mutant Htt.
Giardia mitosomes and trichomonad hydrogenosomes share a common mode of protein targeting
Authors: Dolezal Pavel , Smíd Ondrej , Rada Petr , Zubácová Zuzana , Bursać Dejan , Suták Robert , Nebesárová Jana , Lithgow Trevor , Tachezy Jan
Published: July 2005

Mitochondria are archetypal organelles of endosymbiotic origin in eukaryotic cells. Some unicellular eukaryotes (protists) were considered to be primarily amitochondrial organisms that diverged from the eukaryotic lineage before the acquisition of the premitochondrial endosymbiont, but their amitochondrial status was recently challenged by the discovery of mitochondria-like double membrane-bound organelles called mitosomes. Here, we report that proteins targeted into mitosomes of
Giardia intestinalis
have targeting signals necessary and sufficient to be recognized by the mitosomal protein import machinery. Expression of these mitosomal proteins in
Trichomonas vaginalis
results in targeting to hydrogenosomes, a hydrogen-producing form of mitochondria. We identify, in
Giardia
and
Trichomonas
, proteins related to the component of the translocase in the inner membrane from mitochondria and the processing peptidase. A shared mode of protein targeting supports the hypothesis that mitosomes, hydrogenosomes, and mitochondria represent different forms of the same fundamental organelle having evolved under distinct selection pressures.
Constitutively active L-type Ca
2+
channels
Authors: Navedo Manuel F. , Amberg Gregory C. , Votaw V. Scott , Santana Luis F.
Published: July 2005

Ca
2+
influx through L-type Ca
2+
channels (LTCCs) influences numerous physiological processes ranging from contraction in muscle and memory in neurons to gene expression in many cell types. However, the spatiotemporal organization of functional LTCCs has been nearly impossible to investigate because of methodological limitations. Here, we examined LTCC function with high temporal and spatial resolution using evanescent field fluorescence microscopy. Surprisingly, we found that LTCCs operated in functionally organized clusters, not necessarily as individual proteins. Furthermore, LTCC function in these clusters does not appear to be controlled by simple stochastic gating but instead by a PKC-dependent switch mechanism. This work suggests that resting intracellular free calcium concentration in arterial myocytes is predominantly controlled by this process in combination with rare voltage-dependent openings of individual LTCCs. We propose that Ca
2+
influx via persistent LTCCs may be an important mechanism regulating steady-state local and global Ca
2+
signals.
The high-pressure phase of alumina and implications for Earth's D″ layer
Authors: Oganov Artem R. , Ono Shigeaki
Published: July 2005

Using
ab initio
simulations and high-pressure experiments in a diamond anvil cell, we show that alumina (Al
2
O
3
) adopts the CaIrO
3
-type structure above 130 GPa. This finding substantially changes the picture of high-pressure behavior of alumina; in particular, we find that perovskite structure is never stable for Al
2
O
3
at zero Kelvin. The CaIrO
3
-type phase suggests a reinterpretation of previous shock-wave experiments and has important implications for the use of alumina as a window material in shock-wave experiments. In particular, the conditions of the stability of this phase correspond to those at which shock-wave experiments indicated an increase of the electrical conductivity. If this increase is caused by high ionic mobility in the CaIrO
3
-type phase of Al
2
O
3
, similar effect can be expected in the isostructural postperovskite phase of MgSiO
3
(which is the dominant mineral phase in the Earth's D″ layer). The effect of the incorporation of Al on the perovskite/postperovskite transition of MgSiO
3
is discussed.
Expression, physiological action, and coexpression patterns of neuropeptide Y in rat taste-bud cells
Authors: Zhao Fang-li , Shen Tiansheng , Kaya Namik , Lu Shao-gang , Cao Yu , Herness Scott
Published: July 2005

Recent studies have suggested that neuropeptides could play previously unrecognized functional roles in peripheral gustation. To date, two peptides, cholecystokinin and vasoactive intestinal peptide, have been localized to subsets of taste-bud (TB) cells (TBC) and one, cholecystokinin, has been demonstrated to produce excitatory physiological actions. This study extends our knowledge of neuropeptides in TBC in three significant ways. First, using techniques of immunocytochemistry and RT-PCR, evidence is presented for the expression of a third peptide, neuropeptide Y (NPY). Like other peptide expression patterns, NPY expression is circumscribed to a subset of cells within the taste bud. Second, using physiological studies, we demonstrate that NPY specifically enhances an inwardly rectifying potassium current via NPY-Y1 receptors. This action is antagonistic to the previously demonstrated inhibitory effect exerted by cholecystokinin on the same current, thus providing important clues to their signaling roles in the TB. Third, using the technique of double-labeled fluorescent immunocytochemistry, the relationship of three subsets of neuropeptide-expressing TB cells to one another was examined. Remarkably, NPY expressions, although fewer in number than either the cholecystokinin or vasoactive intestinal peptide subsets, overlapped 100% with either peptide. Collectively, these three observations transform previously suggestive roles of neuromodulation by peptides in TB cells to more concrete signaling pathways. The extensive colocalization of these peptides suggests they may be subject to similar presynaptic influences of release yet have antagonistic postsynaptic actions. The convergence or divergence of these postsynaptic actions awaits further investigation.
DNA-based vaccines activate innate and adaptive antitumor immunity by engaging the NKG2D receptor
Authors: Zhou He , Luo Yunping , Lo Jeng-fan , Kaplan Charles D. , Mizutani Masato , Mizutani Noriko , Lee Jiing-Dwan , Primus F. James , Becker Jürgen C. , Xiang Rong , Reisfeld Ralph A.
Published: July 2005

The interaction of NKG2D, a stimulatory receptor expressed on natural killer (NK) cells and activated CD8+T cells, and its ligands mediates stimulatory and costimulatory signals to these cells. Here, we demonstrate that DNA-based vaccines, encoding syngeneic or allogeneic NKG2D ligands together with tumor antigens such as survivin or carcinoembryonic antigen, markedly activate both innate and adaptive antitumor immunity. Such vaccines result in highly effective, NK- and CD8+T cell-mediated protection against either breast or colon carcinoma cells in prophylactic and therapeutic settings. Notably, this protection was irrespective of the NKG2D ligand expression level of the tumor cells. Hence, this strategy has the potential to lead to widely applicable and possibly clinically useful DNA-based cancer vaccines.
Role of pro-IGF-II processing by proprotein convertase 4 in human placental development
Authors: Qiu Qing , Basak Ajoy , Mbikay Majambu , Tsang Benjamin K. , Gruslin Andrée
Published: July 2005

Fetal growth restriction (intrauterine growth restriction, IUGR) is a leading cause of perinatal mortality. However, the causes of aberrant development of the placenta and, thus, of the fetus, are not currently known. Insulin-like growth factor II (IGF-II) has been shown to be an important regulator of fetoplacental growth. This growth factor must undergo posttranslational processing, and, thus, we hypothesized that aberrant processing of pro-IGF-II to IGF-II may be a cause of IUGR. Here, we have found that the proprotein convertase PC4 is expressed in the human placenta and that it cleaves pro-IGF-II to generate the intermediate processed form, IGF-II (1-102) and, subsequently, mature IGF-II (1-67), which are accounted for by the removal of terminal basic residues by carboxypeptidases. This processing confers the ability of IGF-II to activate invasive trophoblast cells through AKT phosphorylation, whereas inhibition of PC4 by a PC4-specific inhibitor blocks pro-IGF-II processing and reduces trophoblast cell migration, which can be partly restored by addition of mature IGF-II. Consistent with the hypothesis that IGF-II processing is implicated in IUGR, sera of patients carrying IUGR fetuses displayed elevated levels of pro-IGF-II. Thus, abnormal processing of IGF-II by PC4 may represent a previously uncharacterized mechanism involved in the pathophysiology of fetoplacental growth restriction, and elevated pro-IGF-II may be a useful clinical marker for risk of IUGR.
Docosahexaenoic acid: A positive modulator of Akt signaling in neuronal survival
Authors: Akbar Mohammed , Calderon Frances , Wen Zhiming , Kim Hee-Yong
Published: July 2005

Phosphatidylinositol 3-kinase [PI (3)K]/Akt signaling is a critical pathway in cell survival. Here, we demonstrate a mechanism where membrane alteration by the n-3 fatty acid status affects Akt signaling, impacting neuronal survival. Docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid highly enriched in neuronal membranes, promotes neuronal survival by facilitating membrane translocation/activation of Akt through its capacity to increase phosphatidylserine (PS), the major acidic phospholipid in cell membranes. The activation of PI (3)K and phosphatidylsinositol triphosphate formation were not affected by DHA, indicating that membrane interaction of Akt is the event responsible for the DHA effect. Docosapentaenoic acid, which replaces DHA during n-3 fatty acid deficiency, was less effective in accumulating PS and translocating Akt and thus less effective in preventing apoptosis. Consistently,in vivoreduction of DHA by dietary depletion of n-3 fatty acids decreased hippocampal PS and increased neuronal susceptibility to apoptosis in cultures. This mechanism may contribute to neurological deficits associated with n-3 fatty acid deficiency and support protective effects of DHA in pathological models such as brain ischemia or Alzheimer's disease.
Retrograde movement of tRNAs from the cytoplasm to the nucleus in
Saccharomyces cerevisiae
Authors: Shaheen Hussam H. , Hopper Anita K.
Published: July 2005

In eukaryotes, tRNAs transcribed in the nucleus function in cytoplasmic protein synthesis. The Ran-GTP-binding exportin, Los1p/Xpo-t, and additional pathway(s) mediate tRNA transport to the cytoplasm. Although tRNA movement was thought to be unidirectional, recent reports that yeast precursor tRNA splicing occurs in the cytoplasm, whereas fully spliced tRNAs can reside in the nucleus, require that either the precursor tRNA splicing machinery or mature tRNAs move from the cytoplasm to the nucleus. Our data argue against the first possibility and strongly support the second. Combining heterokaryon analysis with fluorescence
in situ
hybridization, we show that a foreign tRNA encoded by one nucleus can move from the cytoplasm to a second nucleus that does not encode the tRNA. We also discovered nuclear accumulation of endogenous cytoplasmic tRNAs in haploid yeast cells in response to nutritional deprivation. Nuclear accumulation of cytoplasmic tRNA requires Ran and the Mtr10/Kap111 member of the importin-β family. Retrograde tRNA nuclear import may provide a novel mechanism to regulate gene expression in eukaryotes.
The RNaseIII enzyme
Dicer
is required for morphogenesis but not patterning of the vertebrate limb
Authors: Harfe Brian D. , McManus Michael T. , Mansfield Jennifer H. , Hornstein Eran , Tabin Clifford J.
Published: July 2005

The RNaseIII-containing enzyme
Dicer
is believed to be required for the processing of most, if not all, microRNAs (miRNAs) and for processing long dsRNA into small interfering RNAs. Because the complete loss of
Dicer
in both zebrafish and mice results in early embryonic lethality, it has been impossible to determine what role, if any,
Dicer
has in patterning later tissues in the developing vertebrate embryo. To bypass the early requirement of
Dicer
in development, we have created a conditional allele of this gene in mice. Using transgenes to drive Cre expression in discrete regions of the limb mesoderm, we find that removal of
Dicer
results in the loss of processed miRNAs. Phenotypically, developmental delays, in part due to massive cell death as well as disregulation of specific gene expression, lead to the formation of a much smaller limb. Thus,
Dicer
is required for the formation of normal mouse limbs. Strikingly, however, we did not detect defects in basic patterning or in tissue-specific differentiation of
Dicer
-deficient limb buds.
Chemical exchange 2D IR of hydrogen-bond making and breaking
Authors: Kim Yung Sam , Hochstrasser Robin M.
Published: July 2005

The involvement of chemical exchange in 2D IR heterodyne echo spectroscopy is characterized through the hydrogen-bond exchange between CH3OH and the CN of CH3CN. The exchange dynamics on the hydrogen-bond potential surfaces associated with different quantum states of the high-frequency CN stretching mode contributes to strong cross peaks between CN groups in two different chemical configurations and provides firm evidence of the hydrogen exchange between them. In analogy with NMR, the chemical exchange is seen in both slow and dynamic regimes. The relative magnitudes of the cross peaks at various population periods measure the picosecond regime time constants for H-bond transfer, whereas the temperature dependences indicate that the activation energy for the exchange from the H-bonded state to the free state is ≈6.2 kJ·mol–1. The results suggest that the hydrogen-bond dynamics is very similar in both vibrational quantum states of CN, suggesting that this stretching mode is not strongly coupled to the H-bond breaking reaction coordinate. The likely manifestations of chemical exchange in 2D IR experiments are discussed.
Toward a live microbial microbicide for HIV: Commensal bacteria secreting an HIV fusion inhibitor peptide
Authors: Rao Srinivas , Hu Stella , McHugh Louise , Lueders Kira , Henry Ken , Zhao Qi , Fekete Richard A. , Kar Sudeshna , Adhya Sankar , Hamer Dean H.
Published: July 2005

Most HIV transmission occurs on the mucosal surfaces of the gastrointestinal and cervicovaginal tracts, both of which are normally coated by a biofilm of nonpathogenic commensal bacteria. We propose to genetically engineer such naturally occurring bacteria to protect against HIV infection by secreting antiviral peptides. Here we describe the development and characterization of Nissle 1917, a highly colonizing probiotic strain of
Escherichia coli
, secreting HIV-gp41-hemolysin A hybrid peptides that block HIV fusion and entry into target cells. By using an appropriate combination of cis- and transacting secretory and regulatory signals, micromolar secretion levels of the anti-HIV peptides were achieved. The genetically engineered Nissle 1917 were capable of colonizing mice for periods of weeks to months, predominantly in the colon and cecum, with lower concentrations of bacteria present in the rectum, vagina, and small intestine. Histological and immunocytochemical examination of the colon revealed bacterial growth and peptide secretion throughout the luminal mucosa and in association with epithelial surfaces. The use of genetically engineered live microbes as anti-HIV microbicides has important potential advantages in economy, efficacy, and durability.
Ground-based and remotely sensed nutrient availability across a tropical landscape
Authors: Porder Stephen , Asner Gregory P. , Vitousek Peter M.
Published: July 2005

Tropical soils often are assumed to be highly weathered and thus nutrient-depleted, but this prediction applies primarily to geomorphically stable surfaces. Topography complicates the assumption of nutrient depletion, because erosion can enhance the supply of nutrients to tropical ecosystems. Consequently, understanding nutrient availability across landscapes requires a spatially explicit assessment of the relative strength of depletion and enhancement. We document the relationship between foliar nutrients and topographic position across a 20-km
2
, 4- to 5-million-year-old eroded landscape in Kaua'i, Hawai'i, and use this relationship to build a bottom-up map of predicted nutrient availability across this landscape. Only ≈17% of the landscape is nutrient-poor, mostly on stable uplands; nutrient availability on slopes and valley bottoms is much higher, in some cases similar to the most fertile montane forests in the Hawaiian Islands. This pattern was corroborated by top-down remote sensing of area-integrated canopy phosphorus concentrations.
Use of BMI in the assessment of undernutrition in older subjects: reflecting on practice
Authors: Cook Z. , Kirk S. , Lawrenson S. , Sandford S.
Published: July 2005

In recent years there has been a proliferation of nutrition screening tools but undernutrition remains prevalent amongst older subjects. Screening tools commonly include BMI as the widely-accepted ‘gold standard’ indicator of malnutrition. Whilst BMI may be an appropriate tool for population studies when it can be measured accurately in research conditions, the use of BMI in clinical practice may mask important weight changes and result in a failure to alert healthcare staff to a nutritional problem. The inclusion of BMI has been identified as a barrier to completing the screening process at ward level. Also, feedback from dietitians working with older subjects indicates that 72.5% of those using BMI express concerns that it is of limited use for practical reasons or that the reference range (20–25 kg/m2) is not appropriate to older subjects. Further evidence questions whether or not BMI is applicable for inclusion in methods used to identify an older subject at risk of undernutrition in a variety of care settings. In view of these findings it is advocated that weight change over a period of time together with clinical judgement is a far superior prognostic indicator of undernutrition. Despite screening, there is evidence that inpatients continue to lose weight before discharge. Further experiential evidence from both community and ward settings suggests that inadequacies in care planning, food provision and a lack of assistance with feeding are common. In order to improve the management of undernutrition in older subjects it is therefore recommended that the focus of attention should be on addressing these practical issues and on the effective monitoring of these processes.
Probing the Geometry of the Inner Vestibule of BK Channels with Sugars
Authors: Brelidze Tinatin I. , Magleby Karl L.
Published: July 2005

The geometry of the inner vestibule of BK channels was probed by examining the effects of different sugars in the intracellular solution on single-channel current amplitude (unitary current). Glycerol, glucose, and sucrose decreased unitary current through BK channels in a concentration- and size-dependent manner, in the order sucrose > glucose > glycerol, with outward currents being reduced more than inward currents. The fractional decrease of outward current was more directly related to the fractional hydrodynamic volume occupied by the sugars than to changes in osmolality. For concentrations of sugars ≤1 M, the i/V plots for outward currents in the presence and absence of sugar superimposed after scaling, and increasing K+i from 150 mM to 2 M increased the magnitudes of the i/V plots with little effect on the shape of the scaled curves. These observations suggest that sugars ≤1 M reduce outward currents mainly by entering the inner vestibule and reducing the movement of K+ through the vestibule, rather than by limiting diffusion-controlled access of K+ to the vestibule. With 2 M sucrose, the movement of K+ into the inner vestibule became diffusion limited for 150 mM K+i and voltages >+100 mV. Increasing K+i then relieved the diffusion limitation. An estimate of the capture radius based on the 5 pA diffusion-limited current for channels without the ring of negative charge at the entrance to the inner vestibule was 2.2 Å. Adding the radius of a hydrated K+ (6–8 Å) then gave an effective radius for the entrance to the inner vestibule of 8–10 Å. Such a functionally wide entrance to the inner vestibule together with our observation that even small concentrations of sugar in the inner vestibule reduce unitary current suggest that a wide inner vestibule is required for the large conductance of BK channels.
Evaluation of Corpus Callosum Anisotropy in Young Adults With Fetal Alcohol Syndrome According to Diffusion Tensor Imaging
Authors: Ma Xiangyang , Coles Claire D. , Lynch Mary Ellen , LaConte Stephen M. , Zurkiya Omar , Wang Danli , Hu Xiaoping
Published: July 2005

Background:

Fetal alcohol syndrome (FAS) and associated disorders resulting from maternal alcohol use during gestation are among the most common developmental disorders. However, they are rarely diagnosed and not fully understood in terms of their behavioral and neurocognitive phenotype. Prenatal exposure leads to alterations in facial morphology, growth, and neurocognition. The nature and extent of teratogenic effects on the brain and the relationship between such effects and observed behaviors remain in debate because there are no established markers for the neurological effects of exposure. In this study, we examined the impact of prenatal alcohol exposure on white‐matter integrity in the corpus callosum by using diffusion tensor imaging (DTI) and herein describe the relationship between such effects and observed physical and behavioral outcomes.

Methods:

DTI was used to evaluate diffusion anisotropy in the genu and splenium of corpus callosum in 16 low‐income, primarily African‐American volunteers. Volunteers were recruited from a cohort of young adults who had received neuropsychological evaluations during adolescence. Nine had been prenatally exposed to alcohol and had characteristics of FAS, and seven were nonexposed controls.

Results:

Significant difference in the means for diffusion fractional anisotropy (t= 2.26, df= 9, p <0.002) and apparent diffusion coefficient (t= 2.14, df= 14, p < 0.008) were observed in the corpus callosum of alcohol‐exposed youth compared with nonexposed youth. No significant differences were found in intracranial volume between these groups.

Conclusions:

Our results illustrate that DTI can be used in evaluating the integrity of corpus callosum in alcohol‐exposed individuals. If future studies support these findings, diffusion anisotropy, represented by fractional anisotropy, has the potential to be used as a clinical marker in the diagnosis of FAS.