bluuebunny/crossref_metadata_2025 huggingface dataset:
Calcium currents in the A7r5 smooth muscle-derived cell line. Calcium-dependent and voltage-dependent inactivation.
Authors: Giannattasio B , Jones S W , Scarpa A
Published: May 2004

Inactivation of a dihydropyridine-sensitive calcium current was studied in a cell line (A7r5) derived from smooth muscle of the rat thoracic aorta. Inactivation is faster with extracellular Ca2+ than with Ba2+. In Ba2+, inactivation increases monotonically with depolarization. In Ca2+, inactivation is related to the amount of inward current, so that little inactivation is seen in Ca2+ for brief depolarizations approaching the reversal potential. Longer depolarizations in Ca2+ reveal two components of inactivation, the slower component behaving like that observed in Ba2+. Furthermore, lowering extracellular Ca2+ slows inactivation. These results are consistent with the coexistence of two inactivation processes, a slow voltage-dependent inactivation, and a more rapid current-dependent inactivation which is observable only with Ca2+. Ca(2+)-dependent inactivation is decreased but not eliminated when intracellular Ca2+ is buffered by 10 mM BAPTA, suggesting that Ca2+ acts at a site on or near the channel. We also studied recovery from inactivation after either a short pulse (able to produce significant inactivation only in Ca2+) or a long pulse (giving similar inactivation with either cation). Surprisingly, recovery from Ca(2+)-dependent inactivation was voltage dependent. This suggests that the pathways for recovery from inactivation are similar regardless of how inactivation is generated. We propose a model where Ca(2+)- and voltage-dependent inactivation occur independently.
Cell to cell communication and pH in the frog lens.
Authors: Mathias R T , Riquelme G , Rae J L
Published: May 2004

Fiber cells of the lens are electrically and diffusionally interconnected through extensive gap junctions. These junctions allow fluxes of small solutes to move between inner cells and peripheral cells, where the majority of transmembrane transport takes place. We describe here a method utilizing two intracellular microelectrodes to measure the cell to cell resistance between fiber cells at any given distance into the intact lens. We also use ion-sensitive microelectrodes to record intracellular pH at various depths in the intact lens. We find that gap junctions connecting inner fiber cells differ in pH sensitivity as well as normal coupling resistance from those connecting peripheral cells. The transition occurs in a zone between 500 and 650 microns into the lens. Fiber cells peripheral to this zone have a specific coupling resistance of 1.1 omega cm2, whereas those inside have a specific coupling resistance of 2.7 omega cm2. However, when the cytoplasm of fiber cells is acidified by bubbling with CO2, peripheral cells uncouple and the cell to cell resistance goes up more than 40-fold, whereas junctions inside this zone are essentially unaffected by changes in intracellular pH. In a normal frog lens, the intracellular pH in fiber cells near the lens surface is 7.02, a value significantly alkaline to electrochemical equilibrium. Our data suggest that Na/H exchange and perhaps other Na gradient-dependent mechanisms in the peripheral cells maintain this transmembrane gradient. Deep in the lens, the fiber cell cytoplasm is significantly more acidic (pHi 6.81) due to influx of hydrogen across the inner fiber cell membranes and production of H+ by the inner fiber cells. Because of the normally acid cytoplasm of interior fiber cells, their loss of gap junctional sensitivity to pH may be essential to lens survival.
Sustained and transient calcium currents in horizontal cells of the white bass retina.
Authors: Sullivan J M , Lasater E M
Published: May 2004

Calcium currents were recorded from cultured horizontal cells (HCs) isolated from adult white bass retinas, using the whole-cell patch-clamp technique. Ca2+ currents were enhanced using 10 mM extracellular Ca2+, while Na+ and K+ currents were pharmacologically suppressed. Two components of the Ca2+ current, one transient, the other sustained, were found. The large transient component of the Ca2+ current, which has not been seen before in HCs, is similar, but not identical, to the T-type Ca2+ current described previously in a variety of preparations. The sustained component of the Ca2+ current is similar, but not identical, to the L-type current described in other preparations. FTX, a factor isolated from the venom of the funnel-web spider, Agelenopsis aperta, preferentially and irreversibly blocks the sustained component of the Ca2+ current at very dilute concentrations. The sustained component of the Ca2+ current inactivates slowly, over the course of 15-60 s, in some HCs. This inactivation of the sustained Ca2+ current, when present, is primarily voltage dependent rather than Ca2+ dependent.
Fusion of membranes during fertilization. Increases of the sea urchin egg's membrane capacitance and membrane conductance at the site of contact with the sperm.
Authors: McCulloh D H , Chambers E L
Published: May 2004

The early events of fertilization that precede and cause activation of an egg have not been fully elucidated. The earliest electrophysiological change in the sea urchin egg is a sperm-evoked increase of the egg's membrane conductance. The resulting depolarization facilitates entry of the fertilizing sperm and precludes the entry of supernumerary sperm. The sequence of the increase in the egg's membrane conductance, gamete membrane fusion, egg activation, and sperm entry, including causal relationships between these events, are not known. This study reports the use of whole egg voltage clamp and loose patch clamp to monitor simultaneously changes of membrane conductance and capacitance at the site of sperm-egg contact. Measurements were made during sperm-egg interactions where sperm entry readily proceeded or was precluded by maintaining the egg's membrane potential either at large, negative values or at positive values. Whenever the sperm evoked an increase of the egg's membrane conductance, that increase initiated abruptly, was localized to the site of sperm attachment, and was accompanied by a simultaneous abrupt increase of the membrane capacitance. This increase of capacitance indicated the establishment of electrical continuity between gametes (possibly fusion of the gametes' plasma membranes). If sperm entry was blocked by large negative membrane potentials, the capacitance cut off rapidly and simultaneously with a decrease of the membrane conductance, indicating that electrical continuity between gametes was disrupted. When sperm entry was precluded by positive membrane potentials, neither conductance nor capacitance increased, indicating that sperm entry was halted before the fusion of membranes. A second, smooth increase of capacitance was associated with the exocytosis of cortical granules near the sperm in eggs that were activated. Electrical continuity between the gametes always preceded activation of the egg, but transient electrical continuity between the gametes alone was not always sufficient to induce activation.
Oxygen distribution and consumption in the cat retina during normoxia and hypoxemia.
Authors: Linsenmeier R A , Braun R D
Published: May 2004

Oxygen tension (PO2) was measured with microelectrodes within the retina of anesthetized cats during normoxia and hypoxemia (i.e., systemic hypoxia), and photoreceptor oxygen consumption was determined by fitting PO2 measurements to a model of steady-state oxygen diffusion and consumption. Choroidal PO2 fell linearly during hypoxemia, about 0.64 mmHg/mmHg decrease in arterial PO2 (PaO2). The choroidal circulation provided approximately 91% of the photoreceptors' oxygen supply under dark-adapted conditions during both normoxia and hypoxemia. In light adaptation the choroid supplied all of the oxygen during normoxia, but at PaO2's less than 60 mmHg the retinal circulation supplied approximately 10% of the oxygen. In the dark-adapted retina the decrease in choroidal PO2 caused a large decrease in photoreceptor oxygen consumption, from approximately 5.1 ml O2/100 g.min during normoxia to 2.6 ml O2/100 g.min at a PaO2 of 50 mmHg. When the retina was adapted to a rod saturating background, normoxic oxygen consumption was approximately 33% of the dark-adapted value, and hypoxemia caused almost no change in oxygen consumption. This difference in metabolic effects of hypoxemia in light and dark explains why the standing potential of the eye and retinal extracellular potassium concentration were previously found to be more affected by hypoxemia in darkness. Frequency histograms of intraretinal PO2 were used to characterize the oxygenation of the vascularized inner half of the retina, where the oxygen distribution is heterogeneous and simple diffusion models cannot be used. Inner retinal PO2 during normoxia was relatively low: 18 +/- 12 mmHg (mean and SD; n = 8,328 values from 36 profiles) in dark adaptation, and significantly lower, 13 +/- 6 mmHg (n = 4,349 values from 19 profiles) in light adaptation. Even in the dark-adapted retina, 30% of the values were less than 10 mmHg. The mean PO2 in the inner (i.e., proximal) half of the retina was well regulated during hypoxemia. In dark adaptation it was significantly reduced only at PaO2's less than 45 mmHg, and it was reduced less at these PaO2's in light adaptation.
Chemosensory responses in isolated olfactory receptor neurons from Necturus maculosus.
Authors: Dionne V E
Published: May 2004

Olfactory receptor neurons were isolated without enzymes from the mudpuppy, Necturus maculosus, and tested for chemosensitivity. The cells responded to odorants with changes in firing frequency and alterations in excitability that were detected with tight-seal patch electrodes using on-cell and whole-cell recording conditions. Chemosensitive cells exhibited two primary response characteristics: excitation and inhibition. Both types of primary response were observed in different cells stimulated by mixtures of amino acids as well as by the single compound L-alanine, suggesting that there may be more than one transduction pathway for some odorants. Using the normal whole-cell recording method, the chemosensitivity of competent cells washed out rapidly; a resistive whole-cell method was used to record odorant responses under current-clamp conditions. In response to chemical stimulation, excitability appeared to be modulated in several different ways in different cells: odorants induced hyperpolarizing or depolarizing receptor potentials, elicited or inhibited transient, rhythmic generator potentials, and altered excitability without changing the membrane potential or input resistance. These effects suggest that olfactory transduction is mediated through at least three different pathways with effects on four or more components of the membrane conductance. Polychotomous pathways such as these may be important for odor discrimination and for sharpening the "odor image" generated in the olfactory epithelium.
Apical K+ channels in Necturus taste cells. Modulation by intracellular factors and taste stimuli.
Authors: Cummings T A , Kinnamon S C
Published: May 2004

The apically restricted, voltage-dependent K+ conductance of Necturus taste receptor cells was studied using cell-attached, inside-out and outside-out configurations of the patch-clamp recording technique. Patches from the apical membrane typically contained many channels with unitary conductances ranging from 30 to 175 pS in symmetrical K+ solutions. Channel density was so high that unitary currents could be resolved only at negative voltages; at positive voltages patch recordings resembled whole-cell recordings. These multi-channel patches had a small but significant resting conductance that was strongly activated by depolarization. Patch current was highly K+ selective, with a PK/PNa ratio of 28. Patches containing single K+ channels were obtained by allowing the apical membrane to redistribute into the basolateral membrane with time. Two types of K+ channels were observed in isolation. Ca(2+)-dependent channels of large conductance (135-175 pS) were activated in cell-attached patches by strong depolarization, with a half-activation voltage of approximately -10 mV. An ATP-blocked K+ channel of 100 pS was activated in cell-attached patches by weak depolarization, with a half-activation voltage of approximately -47 mV. All apical K+ channels were blocked by the sour taste stimulus citric acid directly applied to outside-out and perfused cell-attached patches. The bitter stimulus quinine also blocked all channels when applied directly by altering channel gating to reduce the open probability. When quinine was applied extracellularly only to the membrane outside the patch pipette and also to inside-out patches, it produced a flickery block. Thus, sour and bitter taste stimuli appear to block the same apical K+ channels via different mechanisms to produce depolarizing receptor potentials.
Relation between veratridine reaction dynamics and macroscopic Na current in single cardiac cells.
Authors: Zong X G , Dugas M , Honerjäger P
Published: May 2004

Veratridine modification of Na current was examined in single dissociated ventricular myocytes from late-fetal rats. Extracellularly applied veratridine reduced peak Na current and induced a noninactivating current during the depolarizing pulse and an inward tail current that decayed exponentially (tau = 226 ms) after repolarization. The effect was quantitated as tail current amplitude, Itail (measured 10 ms after repolarization), relative to the maximum amplitude induced by a combination of 100 microM veratridine and 1 microM BDF 9145 (which removes inactivation) in the same cell. Saturation curves for Itail were predicted on the assumption of reversible veratridine binding to open Na channels during the pulse with reaction rate constants determined previously in the same type of cell at single Na channels comodified with BDF 9145. Experimental relationships between veratridine concentration and Itail confirmed those predicted by showing (a) half-maximum effect near 60 microM veratridine and no saturation up to 300 microM in cells with normally inactivating Na channels, and (b) half-maximum effect near 3.5 microM and saturation at 30 microM in cells treated with BDF 9145. Due to its known suppressive effect on single channel conductance, veratridine induced a progressive, but partial reduction of noninactivating Na current during the 50-ms depolarizations in the presence of BDF 9145, the kinetics of which were consistent with veratridine association kinetics in showing a decrease in time constant from 57 to 22 and 11 ms, when veratridine concentration was raised from 3 to 10 and 30 microM, respectively. As predicted for a dissociation process, the tail current time constant was insensitive to veratridine concentration in the range from 1 to 300 microM. In conclusion, we have shown that macroscopic Na current of a veratridine-treated cardiomyocyte can be quantitatively predicted on the assumption of a direct relationship between veratridine binding dynamics and Na current and as such can be successfully used to analyze molecular properties of the veratridine receptor site at the cardiac Na channel.
Na(+)-dependent Cl-HCO3 exchange in the squid axon. Dependence on extracellular pH.
Authors: Boron W F , Knakal R C
Published: May 2004

Intracellular pH (pHi) in squid giant axons recovers from acid loads by means of a Na(+)-dependent Cl-HCO3 exchanger, the actual mechanism of which might be exchange of: (i) external Na+ and HCO3- for internal Cl- and H+, (ii) Na+ plus two HCO3- for Cl-, (iii) Na+ and CO3= for Cl-, or (iv) the NaCO3- ion pair for Cl-. Here we examine sensitivity of transport to changes of extracellular pH (pHo) in the range 7.1-8.6. We altered pHo in four ways, using: (i) classical "metabolic" disturbances in which we varied [HCO3-]o, [NaCO3-]o, and [CO3=]o at a fixed [CO2]o; (ii) classical "respiratory" disturbances in which we varied [CO2]o, [NaCO3-]o, and [CO3=]o at a fixed [HCO3-]o; (iii) novel mixed-type acid-base disturbances in which we varied [HCO3-]o and [CO2]o at a fixed [CO3=]o and [NaCO3-]o; and (iv) a second series of novel mixed-type disturbances in which we varied [CO2]o, [CO3=]o, and [Na+]o at a fixed [HCO3-]o and [NaCO3-]o. Axons (initial pHi approximately 7.4) were internally dialyzed with a pH 6.5 solution containing 400 mM Cl- but no Na+. After pHi, measured with a glass microelectrode, had fallen to approximately 6.6, dialysis was halted. The equivalent acid extrusion rate (JH) was computed from the rate of pHi recovery (i.e., increase) in the presence of Na+ and HCO3-. When pHo was varied by method (i), which produced the greatest range of [CO3=]o and [NaCO3-]o values, JH increased with pHo in a sigmoidal fashion; the relation was fitted by a pH titration curve with a pK of approximately 7.7 and a Hill coefficient of approximately 3.0. With method (ii), which produced smaller changes in [CO3=]o and [NaCO3-]o, JH also increased with pHo, though less steeply. With method (iii), which involved changes in neither [CO3=]o nor [NaCO3-]o, JH was insensitive to pHo changes. Finally, with method (iv), which involved changes in neither [HCO3-] nor [NaCO3-]o, but reciprocal changes in [CO3=]o and [Na+]o, JH also was insensitive to pHo changes. We found that decreasing pHo from 8.6 to 7.1 caused the apparent Km for external HCO3- ([Na+]o = 425 mM) to increase from 1.0 to 26.7 mM, whereas Jmax was relatively stable. Decreasing pHo from 8.6 to 7.4 caused the apparent Km values for external Na+ ([HCO3-]o = 48 mM) to increase from 8.6 to 81 mM, whereas Jmax was relatively stable.(ABSTRACT TRUNCATED AT 400 WORDS)
Gating of maxi K+ channels studied by Ca2+ concentration jumps in excised inside-out multi-channel patches (myocytes from guinea pig urinary bladder).
Authors: Markwardt F , Isenberg G
Published: May 2004

Currents through maxi K+ channels were recorded in inside-out macro-patches. Using a liquid filament switch (Franke, C., H. Hatt, and J. Dudel. 1987. Neurosci, Lett. 77:199-204) the Ca2+ concentration at the tip of the patch electrode ([Ca2+]i) was changed in less than 1 ms. Elevation of [Ca2+]i from less than 10 nM to 3, 6, 20, 50, 320, or 1,000 microM activated several maxi K+ channels in the patch, whereas return to less than 10 nM deactivated them. The time course of Ca(2+)-dependent activation and deactivation was evaluated from the mean of 10-50 sweeps. The mean currents started a approximately 10-ms delay that was attributed to diffusion of Ca2+ from the tip to the K+ channel protein. The activation and deactivation time courses were fitted with the third power of exponential terms. The rate of activation increased with higher [Ca2+]i and with more positive potentials. The rate of deactivation was independent of preceding [Ca2+]i and was reduced at more positive potentials. The rate of deactivation was measured at five temperatures between 16 and 37 degrees C; fitting the results with the Arrhenius equation yielded an energy barrier of 16 kcal/mol for the Ca2+ dissociation at 0 mV. After 200 ms, the time-dependent processes were in a steady state, i.e., there was no sign of inactivation. In the steady state (200 ms), the dependence of channel openness, N.P(o), on [Ca2+]i yielded a Hill coefficient of approximately 3. The apparent dissociation constant, KD, decreased from 13 microM at -50 mV to 0.5 microM at +70 mV. The dependence of N.P(o) on voltage followed a Boltzmann distribution with a maximal P(o) of 0.8 and a slope factor of approximately 39 mV. The results were summarized by a model describing Ca2+- and voltage-dependent activation and deactivation, as well as steady-state open probability by the binding of Ca2+ to three equal and independent sites within the electrical field of the membrane at an electrical distance of 0.31 from the cytoplasmic side.
Separation of Q beta and Q gamma charge components in frog cut twitch fibers with tetracaine. Critical comparison with other methods.
Authors: Hui C S , Chen W
Published: May 2004

Charge movement was measured in frog cut twitch fibers with the double Vaseline-gap technique. 25 microM tetracaine had very little effect on the maximum amounts of Q beta and Q gamma but slowed the kinetics of the I gamma humps in the ON segments of TEST-minus-CONTROL current traces, giving rise to biphasic transients in the difference traces. This concentration of tetracaine also shifted V gamma 3.7 (SEM 0.7) mV in the depolarizing direction, resulting in a difference Q-V plot that was bell-shaped with a peak at approximately -50 mV. 0.5-1.0 mM tetracaine suppressed the total amount of charge. The suppressed component had a sigmoidal voltage distribution with V = -56.6 (SEM 1.1) mV, k = 2.5 (SEM 0.5) mV, and qmax/cm = 9.2 (SEM 1.5) nC/microF, suggesting that the tetracaine-sensitive charge had a steep voltage dependence, a characteristic of the Q gamma component. An intermediate concentration (0.1-0.5 mM) of tetracaine shifted V gamma and partially suppressed the tetracaine-sensitive charge, resulting in a difference Q-V plot that rose to a peak and then decayed to a plateau level. Following a TEST pulse to greater than -60 mV, the slow inward current component during a post-pulse to approximately -60 mV was also tetracaine sensitive. The voltage distribution of the charge separated by tetracaine (method 1) was compared with those separated by three other existing methods: (a) the charge associated with the hump component separated by a sum of two kinetic functions from the ON segment of a TEST-minus-CONTROL current trace (method 2), (b) the steeply voltage-dependent component separated from a Q-V plot of the total charge by fitting with a sum of two Boltzmann distribution functions (method 3), and (c) the sigmoidal component separated from the Q-V plot of the final OFF charge obtained with a two-pulse protocol (method 4). The steeply voltage-dependent components separated by all four methods are consistent with each other, and are therefore concluded to be equivalent to the same Q gamma component. The shortcomings of each separation method are critically discussed. Since each method has its own advantages and disadvantages, it is recommended that, as much as possible, Q gamma should be separated by more than one method to obtain more reliable results.
Acute Alcohol Use and Suicidal Behavior: A Review of the Literature
Authors: Cherpitel Cheryl J. , Borges Guilherme L.G. , Wilcox Holly C.
Published: May 2004

Abstract: Background: Both acute and chronic use of alcohol are associated with suicidal behavior. However, the differing relationship of each component of alcohol use and possible causal mechanisms remain unclear.

Methods: This article reviews and summarizes associations between acute alcohol consumption (with and without intoxication) and suicidal behavior (both completed suicide and suicide attempts) among adults 19 years and older, as presented in literature published between 1991 and 2001. Possible mechanisms and methodologic challenges for evaluating the association are also discussed. An application of a research design (the case‐crossover study) that has the potential for addressing the effects of acute alcohol use over and above usual or chronic use is presented.

Results: The majority of articles reviewed were restricted to descriptive studies that documented the prevalence of suicide completers or attempters who tested positive for alcohol use. A wide range of alcohol‐positive cases were found for both completed suicide (10–69%) and suicide attempts (10–73%). Common methodologic limitations included the lack of control groups (for evaluating risk conferred by alcohol use), selection and ascertainment bias, and small sample sizes. The results of the case‐crossover pilot study indicated substantially higher risk of suicide during or shortly after use of alcohol compared with alcohol‐free periods.

Conclusions: Although there is a substantial literature of published studies on acute alcohol use and suicidal behavior, the majority of studies focus on completed suicide and report prevalence estimates. Findings from such studies are subject to several possible sources of bias and have not advanced our knowledge of mechanisms in the association between acute alcohol use and suicidal behavior. The case‐crossover design may help to overcome some limitations of these studies and facilitate evaluation of associations and possible causal mechanisms by which acute alcohol use is linked to suicidal behavior.
Suicidal Behaviors and Alcohol Use Among Adolescents: A Developmental Psychopathology Perspective
Authors: Windle Michael
Published: May 2004

Abstract: A developmental psychopathology conceptual model was provided to represent the major categories of risk and protective factors, including alcohol use and binge drinking, that predict suicidal behaviors that range from suicidal thoughts to completed suicides. The conceptual model emphasized the importance of identifying age‐specific sets of risk and protective factors to facilitate the development of effective interventions. As an empirical illustration, a multivariate mediation path model was specified and evaluated with a sample of teens. Findings indicated that several distal variables (e.g., difficult temperament, coping motives for drinking, lower family support, higher percentage of friends using alcohol) significantly predicted mediators (e.g., depression, stressful events, binge drinking) that, in turn, predicted suicidal behaviors. Binge drinking significantly predicted suicide attempts over and above the influence of depression and stressful events.
Serotonergic and Noradrenergic Neurobiology of Alcoholic Suicide
Authors: Underwood Mark D. , Mann J. John , Arango Victoria
Published: May 2004

Abstract: Background: Alcoholism is associated with alterations in the serotonergic and noradrenergic systems. Alcoholics are at a significantly higher risk for suicide than the general population. Altered serotonin (5‐HT) function is associated with suicide and serious suicide attempts. We hypothesized patterns of abnormality associated independently with suicide and with alcoholism.

Methods: Quantitative autoradiographic experiments were performed in human postmortem brain tissue sections from alcoholics, alcoholic‐suicide decedents, nonalcoholic suicide decedents, and normal controls diagnosed by psychological autopsy.

Results: Binding to 5‐HT1A receptors is lower in both alcoholic suicides and alcoholic nonsuicides, suggesting that this effect is related to alcoholism and not suicide. In nonalcoholic suicides, there is a localized increase in 5‐HT1A binding in ventral prefrontal cortex, hypothesized to be a response to less serotonin input. Therefore, alcoholic suicides may fail to up‐regulate ventral prefrontal 5‐HT1A receptors in response to decreased serotonergic transmission, failing to mitigate the impact of less serotonin upon signal transduction and thereby increasing the risk of suicidal behavior. Binding to the serotonin transporter is low in alcoholic suicides but not in alcoholic nonsuicides, suggesting an association with suicide, as nonalcoholic suicides also have decreased binding compared with controls. Evidence of impaired serotonergic innervation associated with alcoholism is also manifested by less 5‐HT1D terminal autoreceptor binding in alcoholics. Nonalcoholic suicides do not have lower 5‐HT1D binding.

In the noradrenergic system, alcoholics (suicide and nonsuicide) and nonalcoholic suicide victims all have fewer pigmented locus ceruleus neurons compared with controls, yet β1‐adrenergic binding is low in both alcoholic groups, whereas α1‐and α2‐adrenergic binding decreases are more pronounced in the alcoholic suicide group. These noradrenergic findings differ from those in nonalcoholic suicides, which have a common feature with alcoholics in having less α2‐and β1‐adrenergic binding but more α1‐adrenergic binding in ventrolateral and orbital cortex.

Conclusion: Extensive but different abnormalities in both the serotonergic and noradrenergic systems have been identified in alcoholics and suicides, suggesting two separate patterns: one related to alcoholism and the other related to suicide. The different patterns suggest different causes and homeostatic responses for alcoholism and suicide.
Interventions in Suicidal Alcoholics
Authors: Cornelius Jack R. , Clark Duncan B. , Salloum Ihsan M. , Bukstein Oscar G. , Kelly Thomas M.
Published: May 2004

Abstract: Research involving suicidal alcoholics is scarce despite the frequent presence of suicidal ideation and behavior among alcoholics. Unfortunately, suicidal ideation is a common exclusion criterion from participation in most studies that are relevant to this population. This article addresses identifying, evaluating, and treating people with alcohol abuse or dependence who display suicidal ideation or suicidal behavior. The state of the art is reviewed regarding interventions, including acute stabilization and specific medications for alcoholism and depression with a special focus on the selective serotonin reuptake inhibitors. Appropriate hospitalization, discharge, and family involvement are discussed. Finally, gaps in knowledge are identified with a focus on priorities and directions for future research.
Petrobacter succinatimandens gen. nov., sp. nov., a moderately thermophilic, nitrate-reducing bacterium isolated from an Australian oil well
Authors: Salinas Monica Bonilla , Fardeau Marie-Laure , Cayol Jean-Luc , Casalot Laurence , Patel Bharat K. C. , Thomas Pierre , Garcia Jean-Louis , Ollivier Bernard
Published: May 2004

A novel Gram-negative, aerobic and moderately thermophilic bacterium, strain 4BONT, was isolated from a non-water-flooded Australian terrestrial oil reservoir. Cells were non-spore-forming straight rods, which were motile by means of a polar flagellum. The optimum growth conditions were 55 °C, pH 6·9 and 0·5 % NaCl. Strain 4BONT was oxidase- and catalase-positive; it grew on fumarate, pyruvate, succinate, formate, ethanol and yeast extract in the presence of oxygen or nitrate as terminal electron acceptor. Nitrate was reduced to nitrous oxide. The DNA G+C content of the strain was 58·6 mol%. The closest phylogenetic relative of strain 4BONT was Hydrogenophilus
thermoluteolus (similarity of 91·8 %), of the β-Proteobacteria. As strain 4BONT is physiologically and phylogenetically different from H. thermoluteolus, it is proposed that it be assigned to a novel species of a novel genus, Petrobacter succinatimandens gen. nov., sp. nov. The type strain is 4BONT (=DSM 15512T=CIP 107790T).
Formosa algae gen. nov., sp. nov., a novel member of the family Flavobacteriaceae
Authors: Ivanova Elena P. , Alexeeva Yulia V. , Flavier Sébastien , Wright Jonathan P. , Zhukova Natalia V. , Gorshkova Natalia M. , Mikhailov Valery V. , Nicolau Dan V. , Christen Richard
Published: May 2004

Four light-yellow-pigmented, Gram-negative, short-rod-shaped, non-motile isolates were obtained from enrichment culture during degradation of the thallus of the brown algaFucus evanescens. The isolates studied were chemo-organotrophic, alkalitolerant and mesophilic. Polar lipids were analysed and phosphatidylethanolamine was the only phospholipid identified. The predominant cellular fatty acids were 15 : 0, i15 : 0, ai15 : 0, i15 : 1 and 15 : 1(n-6). The DNA G+C contents of the four strains were 34·0–34·4 mol%. The level of DNA relatedness of the four isolates was conspecific (88–98 %), indicating that they belong to the same species. The 16S rDNA sequence of strain KMM 3553Twas determined. Phylogenetic analysis revealed that KMM 3553Tformed a distinct phyletic line in the phylumBacteroidetes, classFlavobacteriain the familyFlavobacteriaceaeand that, phylogenetically, this strain could be placed almost equidistant from the generaGelidibacterandPsychroserpens(16S rRNA gene sequence similarities of 94 %). On the basis of significant differences in phenotypic and chemotaxonomic characteristics, it is suggested that the isolates represent a novel species in a new genus; the nameFormosa algaegen. nov., sp. nov. is proposed. The type strain is KMM 3553T(=CIP 107684T).
Agarivorans albus gen. nov., sp. nov., a γ-proteobacterium isolated from marine animals
Authors: Kurahashi Midori , Yokota Akira
Published: May 2004

Six bacterial strains were isolated from healthy marine organisms that were collected from the coast of the Kanto area in Japan. Phylogenetic analysis based on 16S rDNA sequence similarity showed that the six isolates formed a separate cluster in the γ-Proteobacteria and were related to the genera Alteromonas and Glaciecola (<91·6 % similarity). The isolates were related closely to each other (DNA–DNA reassociation values of 74–93 %). The isolates had a polar flagellum and were Gram-negative, mesophilic, strictly aerobic rods that required salt for growth. Distinct phenotypic features of this group included the ability to hydrolyse agar and white pigmentation of colonies. The DNA G+C content of the isolates was 48–50 mol%. The major quinone was Q-8. Phenotypic characteristics of the isolates differed from those of members of the genera Alteromonas and Glaciecola. The name Agarivorans albus gen. nov., sp. nov. is proposed for the six isolates; the type strain is MKT 106T (=IAM 14998T=LMG 21761T).
Psychrophilic pseudomonads from Antarctica: Pseudomonas antarctica sp. nov., Pseudomonas meridiana sp. nov. and Pseudomonas proteolytica sp. nov.
Authors: Reddy Gundlapalli S. N. , Matsumoto Genki I. , Schumann Peter , Stackebrandt Erko , Shivaji Sisinthy
Published: May 2004

Thirty-one bacteria that belonged to the genusPseudomonaswere isolated from cyanobacterial mat samples that were collected from various water bodies in Antarctica. All 31 isolates were psychrophilic; they could be divided into three groups, based on their protein profiles. Representative strains of each of the three groups, namely CMS 35T, CMS 38Tand CMS 64T, were studied in detail. Based on 16S rRNA gene sequence analysis, it was established that the strains were related closely to thePseudomonas fluorescensgroup. Phenotypic and chemotaxonomic characteristics further confirmed their affiliation to this group. The three strains could also be differentiated from each other and the closely related speciesPseudomonas orientalis,Pseudomonas brenneriandPseudomonas migulae, based on phenotypic and chemotaxonomic characteristics and the level of DNA–DNA hybridization. Therefore, it is proposed that strains CMS 35T(=MTCC 4992T=DSM 15318T), CMS 38T(=MTCC 4993T=DSM 15319T) and CMS 64T(=MTCC 4994T=DSM 15321T) should be assigned to novel species of the genusPseudomonasasPseudomonas antarcticasp. nov.,Pseudomonas meridianasp. nov. andPseudomonas proteolyticasp. nov., respectively.
Reinekea marinisedimentorum gen. nov., sp. nov., a novel gammaproteobacterium from marine coastal sediments
Authors: Romanenko Lyudmila A. , Schumann Peter , Rohde Manfred , Mikhailov Valery V. , Stackebrandt Erko
Published: May 2004

A Gram-negative, oxidase- and catalase-positive, rod-shaped bacterium, designated strain KMM 3655T, was isolated from a coastal marine sediment sample. The novel bacterium required sodium ions for growth and grew between 0·5 and 5 % NaCl and at 4–37 °C, but not at 40 °C. It reduced nitrate, formed acids from glucose under aerobic and anaerobic conditions, utilized a limited spectrum of organic substrates and did not produce gelatinase, caseinase, amylase or chitinase. The major isoprenoid quinone was Q8. Polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and an unknown phospholipid. Fatty acid analysis of strain KMM 3655Trevealed C16 : 0, C16 : 1ω7cand C18 : 1ω7cas predominant components. The G+C content of the DNA was 51·1 mol%. Phylogenetic analysis of the 16S rDNA sequence placed the new isolate within theγ-Proteobacteriaas a separate deep branch, with about 90 % sequence similarity to representatives of the genusOceanospirillumand other remotely related genera. Combined phylogenetic and physiological data show that the new marine sediment isolate, KMM 3655T, represents a novel genus and species, for which the nameReinekea marinisedimentorumgen. nov., sp. nov. is proposed. The type strain is KMM 3655T(=DSM 15388T).
Phylogeny of Firmicutes with special reference to Mycoplasma (Mollicutes) as inferred from phosphoglycerate kinase amino acid sequence data
Authors: Wolf Matthias , Müller Tobias , Dandekar Thomas , Pollack J. Dennis
Published: May 2004

The phylogenetic position of the Mollicutes has been re-examined by using phosphoglycerate kinase (Pgk) amino acid sequences. Hitherto unpublished sequences from Mycoplasma mycoides subsp. mycoides, Mycoplasma hyopneumoniae and Spiroplasma citri were included in the analysis. Phylogenetic trees based on Pgk data indicated a monophyletic origin for the Mollicutes within the Firmicutes, whereas Bacilli (Firmicutes) and Clostridia (Firmicutes) appeared to be paraphyletic. With two exceptions, i.e. Thermotoga (Thermotogae) and Fusobacterium (Fusobacteria), which clustered within the Firmicutes, comparative analyses show that at a low taxonomic level, the resolved phylogenetic relationships that were inferred from both the Pgk protein and 16S rRNA gene sequence data are congruent.
Repeat-type distribution in trnL intron does not correspond with species phylogeny: comparison of the genetic markers 16S rRNA and trnL intron in heterocystous cyanobacteria
Authors: Oksanen Ilona , Lohtander Katileena , Sivonen Kaarina , Rikkinen Jouko
Published: May 2004

tRNALeu UAA (trnL) intron sequences are used as genetic markers for differentiating cyanobacteria and for constructing phylogenies, since the introns are thought to be more variable among close relatives than is the 16S rRNA gene, the conventional phylogenetic marker. The evolution of trnL intron sequences and their utility as a phylogenetic marker were analysed among heterocystous cyanobacteria with maximum-parsimony, maximum-likelihood and Bayesian inference by comparing their evolutionary information to that of the 16S rRNA gene. Trees inferred from the 16S rRNA gene and the distribution of two repeat classes in the P6b stem–loop of the trnL intron were in clear conflict. The results show that, while similar heptanucleotide repeat classes I and II in the P6b stem–loop of the trnL intron could be found among distant relatives, some close relatives harboured different repeat classes with a high sequence difference. Moreover, heptanucleotide repeat class II and other sequences from the P6b stem–loop of the trnL intron interrupted several other intergenic regions in the genomes of heterocystous cyanobacteria. Cluster analyses based on conserved intron sequences without loops P6b, P9 and parts of P5 corresponded in most clades to the 16S rRNA gene phylogeny, although the relationships were not resolved well, according to low bootstrap support. Thus, the hypervariable loop sequences of the trnL intron, especially the P6b stem–loop, cannot be used for phylogenetic analysis and conclusions cannot be drawn about species relationships on the basis of these elements. Evolutionary scenarios are discussed considering the origin of the repeats.
Halomonas ventosae sp. nov., a moderately halophilic, denitrifying, exopolysaccharide-producing bacterium
Authors: Martínez-Cánovas M. José , Quesada Emilia , Llamas Inmaculada , Béjar Victoria
Published: May 2004

Halomonas ventosaesp, nov. includes three moderately halophilic, exopolysaccharide-producing strains isolated from saline soils in Jaén (south-eastern Spain). These strains can grow anaerobically using either nitrate or nitrite as terminal electron acceptor and hydrolyse both tyrosine and phenylalanine. Their G+C content varies between 72·6 and 74·3 mol%. The affiliation of the isolates with the genusHalomonaswas confirmed by 16S rRNA gene sequence comparison. DNA–DNA hybridization shows 70·4–82·7 % relatedness among the three strains. Nevertheless, their relatedness is less than 43 % compared to related reference strains. The proposed type strain forHalomonas ventosaeis strain Al12T(=CECT 5797T=DSM 15911T). It grows best at 8 % (w/v) sea salts and requires the presence of Na+. Its major fatty acids are 18 : 1ω7c, 16 : 0, 16 : 1ω7c, and 15 : 0 iso 2-OH. The predominant respiratory lipoquinone found in strain Al12Tis ubiquinone with nine isoprene units (Q-9).
Emendation of the genus Acidomonas Urakami, Tamaoka, Suzuki and Komagata 1989
Authors: Yamashita Shun-ichi , Uchimura Tai , Komagata Kazuo
Published: May 2004

The genus Acidomonas and the species Acidomonas methanolica were recharacterized by using the type strain (NRIC 0498T), three reference strains and 10 methanol-utilizing bacteria that were isolated from activated sludge from three different sewage-treatment plants in Tokyo. Based on 16S rDNA sequences, all strains formed a single cluster within the Acetobacteraceae that was clearly different from the genera Acetobacter, Gluconobacter, Gluconacetobacter, Asaia and Kozakia. The 14 strains were identified as a single species, Acidomonas methanolica, by DNA–DNA similarities, showed DNA G+C contents that ranged from 62 to 63 mol% and had Q-10 as the major quinone, accounting for >87 % of total ubiquinones. Cells of Acidomonas methanolica had a single polar flagellum (or occasionally polar tuft flagella); this differs from a previous study that described peritrichous flagella. Oxidation of acetate was positive for all strains, but oxidation of lactate was weakly positive and varied with strains. Dihydroxyacetone was not produced from glycerol. Pantothenic acid was an essential requirement for growth. The strains tested grew at mostly the same extent at pH 3·0–8·0. Therefore, Acidomonas methanolica should be regarded as acidotolerant, not acidophilic. The descriptions of the genus Acidomonas and the species Acidomonas methanolica Urakami, Tamaoka, Suzuki and Komagata 1989 are emended with newly obtained data.
Characterization of a ‘Bacteroidetes’ symbiont in Encarsia wasps (Hymenoptera: Aphelinidae): proposal of ‘Candidatus Cardinium hertigii’
Authors: Zchori-Fein Einat , Perlman Steve J. , Kelly Suzanne E. , Katzir Nurit , Hunter Martha S.
Published: May 2004

Previously, analysis of 16S rDNA sequences placed a newly discovered lineage of bacterial symbionts of arthropods in the ‘Bacteroidetes’. This symbiont lineage is associated with a number of diverse host reproductive manipulations, including induction of parthenogenesis in severalEncarsiaparasitoid wasps (Hymenoptera: Aphelinidae). In this study, electron microscopy and phylogenetic analysis of the 16S rRNA andgyrBgenes of symbionts fromEncarsia hispidaandEncarsia pergandiellaare used to describe and further characterize these bacteria. Phylogenetic analyses based on these two genes showed that theEncarsiasymbionts are allied with theCytophaga aurantiacalineage within the ‘Bacteroidetes’, with their closest described relative being the acanthamoeba symbiont ‘CandidatusAmoebophilus asiaticus’. TheEncarsiasymbionts share 97 % 16S rDNA sequence similarity withBrevipalpusmite andIxodestick symbionts and 88 % sequence similarity with ‘CandidatusA. asiaticus’. Electron microscopy revealed that many of the bacteria found in the ovaries of the twoEncarsiaspecies contained a regular, brush-like array of microfilament-like structures that appear to be characteristic of the symbiont. Finally, the role of this bacterium in parthenogenesis induction inE. hispidawas confirmed. Based on phylogenetic analyses and electron microscopy, classification of the symbionts fromEncarsiaas ‘CandidatusCardinium hertigii’ is proposed.
Use of recA as an alternative phylogenetic marker in the family Vibrionaceae
Authors: Thompson C. C. , Thompson F. L. , Vandemeulebroecke K. , Hoste B. , Dawyndt P. , Swings J.
Published: May 2004

This study analysed the usefulness ofrecAgene sequences as an alternative phylogenetic and/or identification marker for vibrios. TherecAsequences suggest that the genusVibriois polyphyletic. The high heterogeneity observed within vibrios was congruent with former polyphasic taxonomic studies on this group.Photobacteriumspecies clustered together and apparently nested within vibrios, whileGrimontia hollisaewas apart from other vibrios. Within the vibrios,Vibrio choleraeandVibrio mimicusclustered apart from the other genus members.Vibrio harveyi- andVibrio splendidus-related species formed compact separated groups. On the other hand, species related toVibrio tubiashiiappeared scattered in the phylogenetic tree. The pairsVibrio coralliilyticusandVibrio neptunius,Vibrio nereisandVibrio xuiiandV. tubiashiiandVibrio brasiliensisclustered completely apart from each other. There was a correlation of 0·58 betweenrecAand 16S rDNA pairwise similarities. Strains of the same species have at least 94 %recAsequence similarity.recAgene sequences are much more discriminatory than 16S rDNA. For 16S rDNA similarity values above 98 % there was a wide range ofrecA similarities, from 83 to 99 %.
Reassignment of the basidiomycetous yeasts Trichosporon pullulans to Guehomyces pullulans gen. nov., comb. nov. and Hyalodendron lignicola to Trichosporon lignicola comb. nov.
Authors: Fell Jack W. , Scorzetti Gloria
Published: May 2004

Nucleotide sequence analyses of the hymenomycetous yeasts demonstrated that Hyalodendron lignicola should be considered as a member of the genus Trichosporon within the Trichosporonales and that Trichosporon pullulans is associated closely with the Cystofilobasidiales, rather than the Trichosporonales. Accordingly, the following proposals are made: Trichosporon lignicola comb. nov. and Guehomyces gen. nov., to accommodate Guehomyces pullulans comb. nov. in the Cystofilobasidiales.
Propionispora hippei sp. nov., a novel Gram-negative, spore-forming anaerobe that produces propionic acid
Authors: Abou-Zeid Dunja Manal , Biebl Hanno , Spröer Cathrin , Müller Rolf-Joachim
Published: May 2004

A Gram-negative, spore-forming anaerobe, KST, was isolated from an enrichment culture that was set up for anaerobic degradation of the aliphatic polyester poly(propylene adipate). The strain had the cellular organization of Sporomusa, vibrio-shaped cells and terminal round spores, and fermented sugars and sugar alcohols to propionic and acetic acid. Based on the morphological and physiological features as well as on a 16S rRNA gene similarity of 98 %, it was grouped with Propionispora vibrioides. A relatively low DNA–DNA hybridization value with the type strain of this species (47 %), and differences in substrate utilization and spore morphology, suggested that the strain should be classified in a separate species, Propionispora hippei sp. nov., with KST as the type strain (=DSM 15287T=ATCC BAA-665T).
cis-Regulatory Elements for Mesophyll-Specific Gene Expression in the C4 PlantFlaveria trinervia, the Promoter of the C4 Phosphoenolpyruvate Carboxylase Gene[W]
Authors: Gowik Udo , Burscheidt Janet , Akyildiz Meryem , Schlue Ute , Koczor Maria , Streubel Monika , Westhoff Peter
Published: May 2004

C4 photosynthesis depends on the strict compartmentalization of CO2 assimilatory enzymes. cis-regulatory mechanisms are described that ensure mesophyll-specific expression of the gene encoding the C4 isoform of phosphoenolpyruvate carboxylase (ppcA1) of the C4 dicot Flaveria trinervia. To elucidate and understand the anatomy of the C4  ppcA1 promoter, detailed promoter/reporter gene studies were performed in the closely related C4 species F. bidentis, revealing that the C4 promoter contains two regions, a proximal segment up to −570 and a distal part from −1566 to −2141, which are necessary but also sufficient for high mesophyll-specific expression of the β-glucuronidase reporter gene. The distal region behaves as an enhancer-like expression module that can direct mesophyll-specific expression when inserted into the ppcA1 promoter of the C3 plant F. pringlei. Mesophyll expression determinants were restricted to a 41-bp segment, referred to as mesophyll expression module 1 (Mem1). Evolutionary and functional studies identified the tetranucleotide sequence CACT as a key component of Mem1.