Effects of ATP and cyclic AMP on the (Na+ + K+ + 2Cl-)-cotransport system in turkey erythrocytes

As turkey erythrocytes were progressively depleted of ATP by preincubation with dinitrophenol, the (Na+ + K+ + 2Cl-)-cotransport system (assayed by the bumetanide-sensitive fraction of 86Rb+ influx) became less responsive to activation. The dependence upon intracellular ATP concentration was significantly steeper for transport activated by hypertonic shock (halfmaximal activity at 0.7 mM ATP) than for that activated by either epinephrine or cyclic AMP (halfmaximal activity at 1.7 mM ATP). Upon removal of epinephrine or cyclic AMP from cells that had been preincubated with those substances, bumetanide-sensitive transport activity declined sharply, even though the intracellular cyclic AMP concentration was still over 10-fold that required to maximally activate the transport system. These data are in agreement with the notion that the (Na+ + K+ + 2Cl-)-cotransport system in turkey erythrocytes is activated by cyclic AMP, presumably through the 'classical' pathway involving a protein kinase. They do however indicate that some other, as yet undefined aspect of cyclic AMP metabolism is important for the maintenance of transport activity.     

α-MSH Stimulates Glucose Uptake in Mouse Muscle and Phosphorylates Rab-GTPase-Activating Protein TBC1D1 Independently of AMPK

The melanocortin system includes five G-protein coupled receptors (family A) defined as MC1R-MC5R, which are stimulated by endogenous agonists derived from proopiomelanocortin (POMC). The melanocortin system has been intensely studied for its central actions in body weight and energy expenditure regulation, which are mainly mediated by MC4R. The pituitary gland is the source of various POMC-derived hormones released to the circulation, which raises the possibility that there may be actions of the melanocortins on peripheral energy homeostasis. In this study, we examined the molecular signaling pathway involved in α-MSH-stimulated glucose uptake in differentiated L6 myotubes and mouse muscle explants. In order to examine the involvement of AMPK, we investigate α-MSH stimulation in both wild type and AMPK deficient mice. We found that α-MSH significantly induces phosphorylation of TBC1 domain (TBC1D) family member 1 (S237 and T596), which is independent of upstream PKA and AMPK. We find no evidence to support that α-MSH-stimulated glucose uptake involves TBC1D4 phosphorylation (T642 and S704) or GLUT4 translocation.     

Using Echo Ultrasound from Schooling Fish to Detect and Classify Fish Types

Fish finders have already been widely available in the fishing market for a number of years.However,the sizes of these fishfinders are too big and their prices are expensive to suit for the research of robotic fish or mini-submarine.The goal of thisresearch is to propose a low-cost fish detector and classifier which suits for underwater robot or submarine as a proximity sensor.With some pre-condition in hardware and algorithms,the experimental results show that the proposed design has good per-formance,with a detection rate of 100 % and a classification rate of 94 %.Both the existing type of fish and the group behaviorcan be revealed by statistical interpretations such as hovering passion and sparse swimming mode.     

The membrane topology of proton-pumping Escherichia coli transhydrogenase determined by cysteine labeling.

The membrane topology of proton-pumping nicotinamide-nucleotide transhydrogenase from Escherichia coli was determined by site-specific chemical labeling. A His-tagged cysteine-free transhydrogenase was used to introduce unique cysteines in positions corresponding to potential membrane loops. The cysteines were reacted with fluorescent reagents, fluorescein 5-maleimide or 2-[(4'-maleimidyl)anilino]naphthalene-6-sulfonic acid, in both intact cells and inside-out vesicles. Labeled transhydrogenase was purified with a small-scale procedure using a metal affinity resin, and the amount of labeling was measured as fluorescence on UV-illuminated acrylamide gels. The difference in labeling between intact cells and inside-out vesicles was used to discriminate between a periplasmic and a cytosolic location of the residues. The membrane region was found to be composed of 13 helices (four in the alpha-subunit and nine in the beta-subunit), with the C terminus of the alpha-subunit and the N terminus of the beta-subunit facing the cytosolic and periplasmic sides, respectively. These results differ from previous models with regard to both number of helices and the relative location and orientation of certain helices. This study constitutes the first in which all transmembrane segments of transhydrogenase have been experimentally determined and provides an explanation for the different topologies of the mitochondrial and E. coli transhydrogenases.     

Evidence for the signaling role of methyl jasmonate, methyl salicylate and benzothiazole between poplar (Populus simonii × P. pyramidalis ‘Opera 8277’) cuttings

Interplant communication has been widely demonstrated in plants, especially in herbaceous plants. In this study, mechanical damage was shown to affect the levels of pyrochatechol, chlorogenic acid, gallic acid and p-hydroxyl benzoic acid in poplar (Populus simonii × P. pyramidalis ‘Opera 8277’) cuttings, indicating the activation of defense response. In neighboring intact cuttings, the levels of those phenolics also varied when compared to the control, suggesting the interplant communication between poplar cuttings. Three volatiles, methyl jasmonate, methyl salicylate and benzothiazole, were detected in volatiles emitted from mechanically damaged poplar cuttings. All of them can induce changes in the levels of four phenolics. Therefore, they could act as airborne signals between P. simonii × P. pyramidalis ‘Opera 8277’ cuttings. The different change patterns of phenolic contents induced by different volatiles imply that the defense response activated in neighboring plants may be regulated by multiple signaling pathways. The results also suggest that the entire defense response of plants involves a variety of airborne signals in wound-induced volatiles.     

Characteristics of carbohydrate metabolism in the rat liver in thiamine deficiency

Thiamine deficiency in rats induced by oxythiamine is accompanied by an increase in the free NADP+/NADPH ratio in liver tissue, which results in multifold stimulation of the metabolite flux in the oxidation branch of the pentose cycle. The increase in the intracellular concentrations of isocitrate and alpha-ketoglutarate with a simultaneous decrease of malate in the liver of vitamin-deficient rats points to the inhibition of alpha-ketoglutarate dehydrogenase responsible for the anomalous metabolism under conditions of thiamine deficiency. The decrease of the functional activity of the tricarboxylic acid cycle is concomitant with the activation of conversions in the oxidation branch of the pentose cycle, glucuronate and glycolytic pathways of carbohydrate metabolism, which is directed at eliminating the energy deficiency in rats with B1-hypovitaminosis.     

A method for flow cytometric cell cycle analysis of normal and psoriatic human epidermis based on a detergent/citric acid technique for suspension of nuclei

A new method is described for flow cytometric cell cycle analysis of normal and psoriatic human epidermis, based on non-enzymatic tissue disaggregation. The epidermis was isolated by treatment with acetic acid and stored by freezing. After thawing, the epidermis was disintegrated into a nuclear suspension by 3 steps: incubation with dithiotreitol, whirling in a buffer (pH 7.4) with the non-ionic detergent Nonidet P40, EGTA, RNase and spermine, and whirling after addition of citric acid to a final concentration of 1% (pH 2.4). The suspension was stained with propidium iodide and filtered before flow cytometry. The yield of suspended nuclei was approximately 70% of the original number of cells in the tissue. The detergent/citric acid method was found to be preferable to an ultrasonication method previously used on human epidermis. All cell cycle and cell maturation stages were represented in the detergent/citric acid suspension, in contrast to the selection of immature G1, S and G2 stages with enzymatic methods. In the analysis of psoriatic epidermis inadequately matured (parakeratotic) cells were present in the suspension and had to be discriminated by gating on light scattering intensity, as they were not susceptible to lysis and did not stain properly. The fraction of S phase nuclei was on average 1.9% in normal and 7.7% in psoriatic epidermis, thus confirming the results of other investigators using enzymes. The presence of mitotic figures in the suspension was demonstrated by flow sorting. In this way the mitotic fraction was estimated to 0.06% in normal and 0.22% in psoriatic epidermis, confirming histological data of other investigators.