NADPH/NADP ratio could regulate the glyoxylate cycle in Tetrahymena pyriformis

• 1.1. The glyoxylic acid cycle pathway could be regulated through the modulation of the isocitrate dehydrogenase-NADP activity. This enzyme is inhibited by NADPH.
• 2.2. The effect on the glyoxylate cycle flux of variations in the rate of the NADPH-consuming pathways has been studied.
• 3.3. Increase in the rate of NADPH-consuming activity by addition of H₂O₂ produces inhibition of the glyoxylate cycle and decrease in the NADPH/NADP ratio.
• 4.4. These results suggest that the glyoxylate flux in Tetrahymena could be modulated by regulation of NADP-dependent isocitrate dehydrogenase by the NADPH/NADP ratio.

     

Identification of neurons involved in the earthworm Amynthas hawayanus reflex activity

• 1.1. The medial (MGF), lateral (LGF) and motor (RMS-2) giant neurons were confirmed as neural components in the earthworm Amynthas hawayanus polysynaptic reflex circuit by simultaneous potential recording and dye injection.
• 2.2. The reflex was initiated from the mechanoreceptors when evoked by mechanical stimulation but electrical stimulation also evoked an antidromic response in the motoneuron.
• 3.3. The primary reflex response propagates decrementally along both giant axons but directly evoked action potentials conduct in an all-or-none fashion.
• 4.4. The secondary reflex response continues to propagate after the primary response disappears.
• 5.5. A rhythmically discharging neuron of uncertain function was also identified.

     

Modulation of active potassium transport by aldosterone

• 1.1. The role of aldosterone on active potassium transport across lizard colon under voltage-clamped conditions has been investigated.
• 2.2. Control colons exhibited no net potassium flux (J^k_net) despite of the existence of active opposite unidi ectional fluxes.
• 3.3. An important net secretory potassium flux was found in short-circuited aldosterone-stimulated colons.
• 4.4. Mucosal amiloride did not change (J^k_net) either in control or aldosterone-stimulated colons.
• 5.5. Luminal barium alters K ⁺ transport in a manner consistent with the presence of barium-sensitive conductances at the apical membrane of both control and aldosterone-treated colons.
• 6.6. The effects of ouabain and barium on control and aldosterone-induced potassium flows were consistent with a model involving basolateral uptake by an Na ⁺-K ⁺-ATPase and conductive exit across the apical membrane.
• 7.7. The stimulatory effect of aldosterone on potassium secretion is associated with parallel increases of both basolateral K ⁺ entry and the apical conductive pathway.

     

Surface Loops in a Single SH2 Domain Are Capable of Encoding the Spectrum of Specificity of the SH2 Family,

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Highlights

• •Surface loops play an essential role in SH2 domain specificity.
• •Diverse specificities may be obtained from a single SH2 domain by combinatorial mutations in the EF and BG loops.
• •The specificity of a loop mutant correlates with the sequence characteristics of the bait peptide used in its isolation.

     

Preparation and execution of movement: Parallels between insect and mammalian motor systems

• 1.1. The organization of the motor systems underlying locomotion in insects and mammals is surprisingly similar. There are also parallels between the insect motor system and the system underlying reaching and the occulomotor system in primates.
• 2.2. The movements generated by all these systems are planned or prepared before their execution and there is a partial separation of circuits for preparation and execution.
• 3.3. These circuits consist of multiple descending pathways interconnected to form overlapping loops which work co-operatively to determine the motor output. Thus, both insect and mammalian motor systems can be treated as parallel distributed (PDP) systems.
• 4.4. This enables a comparison of functional levels of processing in the different systems and also provides a basis for modelling motor systems with attractor neural networks.

     

Morphology and electrophysiological characteristics of caudodorsal cells of Lymnaea stagnalis in dissociated cell culture

• 1.1. The neuroendocrine caudodorsal cells (CDCs) of Lymnaea stagnalis are a network of about 100 electrotonically coupled neurones. The CDCs release multiple peptides, including an ovulation hormone, during a period of electrical activity, the CDC-discharge.
• 2.2. In isolated brains, a similar period of electrical activity (the afterdischarge) can be induced in all CDCs by a period of intracellular repetitive suprathreshold stimulation of one CDC.
• 3.3. In order to study the regulation of this electrical behaviour in the absence of electrical interactions and in a controlled environment, experiments were performed on CDCs in dissociated cell culture.
• 4.4. Methods for isolation and cell culture are described. Cell cultures had long-term viability and outgrowth of neurities occurred under serum-free conditions.
• 5.5. CDCs in cell culture maintained their capability of producing afterdischarges upon electrical stimulation. Cells in culture appeared more excitable than cells in the intact isolated brain.
• 6.6. The characteristic responses of CDCs in intact isolated brains to acetylcholine and FMRFamide were preserved in cultured CDCs. Both agents induced a transient hyperpolarization of the membrane, inexcitability and inhibition of an ongoing discharge.
• 7.7. In experiments where isolated CDCs were closely apposed, but physically separate, it was found that an afterdischarge in one CDC could induce a discharge in the other CDC.
• 8.8. These results confirm previous results which showed that an excitatory factor is released from the brain during the afterdischarge (Ter Maat et al., 1988, Brain Res., 43, 77–82), and demonstrate that this excitatory factor is released from the CDCs themselves.

     

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Gluconeogenesis in hepatocytes determined with [2-13C] acetate and quantitative 13C NMR spectroscopy

• 1.1. In the present study the major metabolic pathways of glucose metabolism were determined in isolated liver cells using [2-¹³C]acetate and ¹³C magnetic resonance spectroscopy.
• 2.2. The relative reaction rates of glucose synthesis to the TCA cycle were determined from the ¹³C distribution in glucose where the overall ¹³C enrichment of glucose was 6.41 ± 1.94% (mean ± SD; n = 6) and the mean ¹³C enrichment of C1, C2, C5, C6 to C3, C4 was 2.63 ± 0.30.
• 3.3. Since the distribution of tracer in glucose is a function of the relative entry rates of pyruvate to acetyl-CoA into the oxaloacetate pool this was calculated to be 0.32 ± 0.15 and the factor for carbon exchange (1/P) between the gluconeogenic pathway and the TCA cycle was calculated to be 1.03 ± 0.20.
• 4.4. With this carbon exchange factor and the approximated ¹³C enrichment of acetyl-CoA the intramitochondrial ¹³C enrichment of phosphoenolpyruvate was calculated and the “true” rate of hepatic gluconeogenesis from phosphoenolpyruvate estimated.
• 5.5. Since acetate was metabolized solely in liver cells the ¹³C enrichment of acetyl-CoA could be approximated from that of 3-hydroxybutyrate.
• 6.6. The carbon 13 enrichment of 3-hydroxybutyrate and phosphoenolpyruvate was 5.89 ± 0.90% and 5.96 ± 1.67%, respectively.
• 7.7. The per cent gluconeogenesis from phosphoenolpyruvate calculated as the ratio of the ¹³C enrichment of glucose to that of 3-hydroxybutyrate times 1/P was 107 ± 8%.
• 8.8. In this study the validity of assessing isotopic exchange at oxaloacetate as suggested by Katz [Katz J. (1985) Am. J. Physiol.248, R391–R399] when interpretation of the data are not obscured by pseudoketogenesis.
• 9.9. Magnetic resonance spectroscopy provides direct information about intramolecular tracer distribution by which flux rates in major metabolic pathways are derived.

     

Adenosine effect on lactate and pyruvate production in the hypoxic guineapig heart

• 1.1. It has been shown that adenosine stimulates glycolysis in some cells and this ability of adenosine was tested in the hypoxic guineapig heart.
• 2.2. Adenosine (10 μM) activated lactate production in the isolated perfused guineapig heart under conditions of normoxia but did not under hypoxia.
• 3.3. Despite this, the nucleoside favorably influenced the energy metabolism of the hypoxic heart as revealed by the better posthypoxic functional recovery (98%) compared to the control without adenosine (78%).
• 4.4. Our findings suggest a role for the glycolytic pathway in this effect of the nucleoside as long as other cardiac energy-yielding pathways are strictly aerobic.

     

12-O-tetradecanoylphorbol-13-acetate enhances glycolysis in rat thymocytes

• 1.1. The potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) induced a rapid increase in glycolysis in rat thymocytes.
• 2.2. The increase in the glycolytic flux was also reflected by elevated fructose 1,6-diphosphate levels.
• 3.3. TPA treatment did not result in an increase of hexokinase, phosphofructokinase or pyruvate kinase when measured in cell homogenates.
• 4.4. It is suggested that the early increase in glycolysis in TPA treated lymphocytes may result from TPA-mediated increase in glucose transport.

     

Electric organ discharge frequency modulation evoked by water vibration in Gymnotus carapo

• 1.1. The electric organ discharge (EOD) frequency modulations evoked by brief water vibration were analysed in the pulse-type fish Gymnotus carapo.
• 2.2. The response consisted of a transient increase of the EOD frequency at short latency (30 msec). Response profiles were characteristic of the specimen and relatively independent on stimulus intensity.
• 3.3. Conversely, they were dependent on stimulation sequence, showing a rapid decrement along successive stimuli and high temporal discrimination.
• 4.4. The brief latencies indicate a relatively simple neural circuit.
• 5.5. The response may be an electrolocation enhancement strategy for the detection of moving objects based on “sampling” the periphery at a higher frequency.

     

Comprehensive Analysis of Individual Variation in the Urinary Proteome Revealed Significant Gender Differences

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Highlights

• •Comprehensive analysis of inter-individual variation of normal urinary proteome.
• •Significant gender differences were observed.
• •Proteins increased in female urine are enriched in immunological pathways.
• •Estimated reference intervals of proteins as the baseline for biomarker discovery.

     

Mitochondrial and peroxisomal fractions derived from human white adipocytes

• 1.1. A procedure is described for the separation of intact peroxisomes from human white adipocytes using a linear metrizamide gradient (20–50% w/v).
• 2.2. Peroxisomes were found in the high density region of the gradient in an intact form.
• 3.3. Mitochondria were distributed in the high density and low density regions of the gradient.
• 4.4. Lysosomes separated well from the peroxisomes, occurring only in the low density region of the gradient.
• 5.5. Low levels of glyoxylate cycle enzyme activities (isocitrate lyase and malate synthase) were detected within the light and heavy mitochondrial pellet fractions.

     

Global Proteome and Ubiquitinome Changes in the Soluble and Insoluble Fractions of Q175 Huntington Mice Brains

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Highlights

• •Quantitative changes in global proteome and ubiquitinome in Huntington's disease.
• •Differential ubiquitination of wild-type and mutant Htt in mice brain.
• •Enriched pathways include vesicle transport and mRNA processing.
• •Correlation between protein and diGly site fold changes.

     

Variations of respiratory rate of Tisbe holothuriae humes (copepoda,harpacticoida) in relation to temperature,salinity and food type

• 1.1. The influence of temperature (14,19, 24°C), salinity (26,32, 38,44%.) and food type (artificial diets: Fryfood, Mytilus, Soya, Yeast, Spirulina) on the respiratory rate of Tisbe holothuriae has been studied.
• 2.2. Oxygen consumption decreased with decreasing temperature, but with a greater rate at supra- or subnormal salinities.
• 3.3. Multiple-regression analysis showed the quadratic effect of temperature and the linear effect of salinity to be the more important factors affecting respiration.
• 4.4. The food type also seems to exert an important effect on oxygen consumption.
• 5.5. A significant lowering of respiration was observed for all food tested when the animals were starved.