Cytochemical adenosine triphosphatase of vorticellid myonemes

A highly specific adenosine triphosphatase has been found to be localized in the contractile apparatus of vorticellids. It is most prominent in the cilia as well as in the myonemes which course the latitudes and longitudes of the cell and spiral in the flat peristome. The stalk displays more activity in the spasmoneme sheath than in the spasmoneme itself. The spasmoneme canal appears negative. A delicate fiber coils around the outside of the stalk in a helix. All these structures may be seen in the living protozoan by phasecontrast microscopy.     

Cochlear function and sodium and potassium activated adenosine triphosphatase

The maintenance of the cation gradients between endolymph and perilymph in the cochlea requires the operation of a cation pump. An adenosine triphosphatase system activated by sodium and potassium is present in high activity in the cochlear membranes (tegmentum vasculosum and stria vascularis). The cochlear microphonic potential is inhibited by perilymphatic perfusion of ouabain and erythrophleine. Since the microphonic potential depends on the high concentration of potassium ions in the endolymph, our findings strongly suggest the operation of an adenosine triphosphatase cation pump system activated by sodium and potassium, in the generation of cochlear cation gradients.     

Actin-myosin interaction: inhibition of the myosin adenosine triphosphatase by actin

In the absence of magnesium ion, the addition of actin to myosin in a 1 :4 ratio has a strong inhibitory effect on the adenosine triphosphatase activity, in contrast to the well-known activating effect of actin in the presence of magnesium ion. This finding suggests that both effects result from a conformational change in the active site of the myosin adenosine triphosphatase.     

Renal concentrating mechanism: possible role for sodium-potassium activated adenosine triphosphatase

Sodium-potassium activated adenosine triphosphatase activity was found to be almost twice as high in renal medulla as in cortex. Infusion of digoxin, a specific inhibitor of the enzyme, into one renal artery of the dog resulted in unilateral natriuresis, impaired concentrating capacity, and reduction of the enzyme activity in both cortex and medulla. It is suggested that the sodium-potassium adenosine triphosphatase plays an important role in urine concentration mechanisms.     

Flagellar adenosine triphosphatase from sea urchin sperm: properties and relation to motility

Adenosine triphosphatase activated by divalent cations is apparently a component of the motile apparatus in flagella of Arbacia sperm, as judged by the activity of this enzyme in intact flagella, glycerol-extracted flagella, and soluble extracts prepared from flagella. However, the variation in the physical properties and in the amount of enzyme obtained after a variety of treatments suggests that additional components are involved in the motile mechanism. These features distinguish the soluble flagellar enzyme from adenosine triphosphatases of other motile cells.     

Steelhead migration: potential temperature effects as indicated by gill adenosine triphosphatase activities

Yearling steelhead trout held in fresh water at cold temperatures (6.5 degrees or 10 degrees C) showed an increase in gill microsomal Na(+), K(+)-stimulated adenosine triphosphatase activity during parr-smolt transformation, whereas trout held in warm water (15 degrees or 20 degrees C) did not. Adenosine triphosphatase activity increased and other indications of transformation were observed in fish transferred from warm to cold water, whereas the reverse occurred on transfer from cold to warm water.     

Sodium-potassium adenosine triphosphatase: acyl phosphate "intermediate" shown to be L-glutamyl-gamma-phosphate

Peptides obtained from pepsin digestion of the phosphorylated and nonphosphorylated forms of a preparation of brain microsomal sodium-potassium-activated adenosine triphosphatase were treated at pH 5.4 with N-(n-propyl-2,3-(3)H) hydroxylamine of high specific activity, then separated by column chromatography, and further digested with pronase. A compound isolated in higher amounts from the phosphorylated enzyme than from the nonphosphorylated enzyme migrated with authentic L-glutamyl-gamma-propylhydroxamate in four chromatographic systems and on electrophoresis on paper at three different pH's. The acyl phosphate "intermediate" in the phosphorylated form of the adenosine-triphosphatase therefore appears to be an L-glutamyl-gamma-phosphate residue.     

Sodium- and potassium-activated adenosine triphosphatase of gills: role in adaptation of teleosts to salt water

The activity of adenosine triphosphatase activated by sodium and potassium ions is greatly increased in the gill and pseudobranch of the euryhaline killifish, Fundulus heteroclitus, after its adaptation to seawater. Adenosine triphosphatase activity in gills of fish in salt water is reduced by hypophysectomy. The data suggest that this enzyme is involved in the excretion of sodiumions by the gill and that the adaptive increase which occurs in seawater is influenced by the hypophysis.     

桑蚕幼虫中肠细胞腺苷三磷酸酶活性的细胞化学

用电镜细胞化学技术研究了桑蚕五龄幼虫中肠组织细胞中ＡＴＰａｓｅ的亚细胞分布。ＡＴＰａｓｅ仅大量分布在中肠圆筒形细胞的微绒毛和杯形细胞在肠腔的开口处、肠壁肌肉的肌质膜上、部分细胞的细胞质膜和细胞器及细胞质中．ＡＴＰａｓｅ的这种分布状态与细胞的功能紧密相关．     

Sodium and potassium effects on skeletal muscle microsomal adenosine triphosphatase and calcium uptake

The relationship between the (Na(+) and K(+))-activated adenosine triphosphatase enzyme system implicated in sodium-transport by cell membranes and the calcium-activated adenosine triphosphatase, which is generally associated with calcium uptake, was examined in microsomes from skeletal muscle. Whereas sodium and potassium did not modify the relatively low adenosine triphosphatase activity seen in the absence of calcium, a pattern similar to that of the sodium-transport enzyme system was seen afer the addition of CaCl(2). The calcium-activated adenosine triphosphatase was stimulated equally by sodium or potassium alone, but both the rate and extent of calcium uptake were enhanced more by potassium than by sodium at concentrations below 0.12 mole per liter. In the absence of either of these ions addition of calcium failed to activate adenosine triphosphatase although significant amounts of calcium were taken up by the microsomes.     

Catecholamine and dibutyryl cyclic AMP effects on myosin adenosine triphosphatase in cultured rat heart cells

Catecholamines and dibutyryl adenosine 3', 5'-monophosphate (dibutyryl cyclic AMP) increase the activity of myosin adenosine triphosphatase in cultured rat heart cells. Dichloroisoproterenol, an inhibitor of the beta receptor of the catecholamines, inhibits the action of the catecholamines but not of cyclic AMP.     

Tritiated digoxin binding to (Na+ + K+)-activated adenosine triphosphatase: possible allosteric site

Tritiated H(3)-digoxin specifically binds to a cardiac (Na(+) + K(+))-activated adenosine triphosphatase. In the presence of adenosine triphosphate and other nucleoside di- and triphosphates, binding is stimulated by sodium ion, the apparent rate constant being similar to that reported for phosphorus-32 incorporation from adenosine triphosphate and for the adenosine triphosphatase activity. In the presence of magnesium, manganese, inorganic phosphate, or other ions, sodium ion inhibits binding. The data support an allosteric type of sodium-potassium ion pump.     

Insulin stimulation of nucleoside triphosphatase activity in isolated nuclear envelopes

The activity of nucleoside triphosphatase, an enzyme that regulates nuclear messenger RNA transport, was measured in highly purified nuclear envelopes isolated from rat liver. Addition of picomolar concentrations of insulin to freshly prepared nuclear envelopes directly increased the enzyme activity. The major effect of insulin on this enzyme was to increase the maximum velocity of its activity; no significant effects were seen on the affinity constant. These studies raise the possibility, therefore, that the nuclear envelope is a site where insulin regulates nuclear functions.     

Immunohistochemistry of adenosine deaminase: implications for adenosine neurotransmission

Immunohistochemical analysis of adenosine deaminase in rat brain revealed an extensive plexus of adenosine deaminase-containing neurons in the basal hypothalamus. These neurons converged on and were most numerous in three major centers, namely, the tuberal, caudal, and postmammillary caudal magnocellular nuclei. Most other brain regions were devoid of cells containing adenosine deaminase. Some adenosine deaminase-containing neurons were retrogradely labeled with the fluorescent dye fast blue when the dye was injected into the frontal cortex and striatum. Specific populations of neurons having high levels of adenosine deaminase may release adenosine as a neurotransmitter.     

Dopamine-beta-hydroxylase: evidence for increased activity in sympathetic neurons during psychotic states

Tritiated dopamine was infused into psychiatric patients during acute psychotic episodes and in remission. An index of the activity of dopamine-beta-hydroxylase of salivary gland sympathetic neurons was determined by measuring the distribution of tritiated metabolites in salivary fluid. Increased synthesis of norepinephrine occurred in acute schizophrenia and in the manic state of manic-depressive psychosis but not in the depressed phase.     

Fluorescent modification of adenosine 3',5'-monophosphate: spectroscopic properties and activity in enzyme systems

The synthesis of a highly fluorescent analog of adenosine 3',5'-monophosphate, namely, 1,N(6)-ethenoadenosine 3',5'-monophosphate, has provided a powerful probe for systems involving adenosine 3',5'-monophosphate. The potential utility of this analog is indicated by its long fluorescent lifetime, detectability at low concentration, and relatively long wavelength of excitation (300 nanometers). In protein kinase systems it is a highly acceptable substitute for adenosine 3',5'-monophosphate.     

大豆根瘤固氮对籽粒中草酸积累的影响

以大豆品种黑农38号为试验材料,研究了结瘤和不结瘤情况下大豆未成熟和成熟荚皮和籽粒中的酰脲(尿囊素和尿囊酸)和草酸含量变化.结果表明:在大豆开花后20 d和45 d,不结瘤处理大豆荚皮和籽粒中根瘤产生的酰脲含量明显降低,而不结瘤处理大豆籽粒中的草酸含量明显高于结瘤处理,荚皮和籽粒中草酸的总含量在2个处理之间没有明显差异.可见,大豆籽粒中的草酸合成前体不是来自根瘤产生酰脲的分解产物乙醛酸.     

高直链淀粉水稻的淀粉积累及相关酶活性关系研究

研究高直链淀粉型水稻品种菲优188花后各时间段内籽粒中不同类型淀粉含量和积累速度的变化,以及淀粉合成相关酶活性的变化,结果发现:该品种花后不同时间段内直链淀粉、支链淀粉、总淀粉含量及其相关酶活性均存在极显著差异.直链淀粉和支链淀粉的积累规律相似,均呈Logistic曲线方程式积累,直链淀粉和支链淀粉积累速度随时间的变化规律也相似,且均与淀粉合成酶呈极显著正相关性.     

Pyrimidine starvation induced by adenosine in fibroblasts and lymphoid cells: role of adenosine deaminase

In the presence of 10(-4) to 10(-5) molar adenosine, established cell lines of fibroblastic or lymphoid origin die of pyrimidine starvation. Less than lethal concentrations inhibit cell growth. Over a broad concentration range, the effects of adenosine are prevented by providing a suitable pyrimidine source. We suggest that the recently described immune deficiency disease associated with absence of adenosine deaminase may be the result of pyrimidine starvation induced by adenosine nucleotides in cells of the lymphoid system.