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E Ball

Publications and source records attributed to E Ball.

At least 55 records · Page 3Linked to original sources
PubMed1987

Arthrin, a myofibrillar protein of insect flight muscle, is an actin-ubiquitin conjugate.

Flight muscles of some insects contain a myofibrillar protein termed arthrin, which is closely related to actin (mw 43,000). Here we demonstrate that arthrin (mw 55,000) is ubiquitinated actin. We show that in Act88FM342, a flightless Drosophila mutant wherein the Act88F actin gene specifies a glu93----lys replacement, isoelectric points of both actin III and arthrin are shifted, revealing that both are encoded by the same gene. Arthrin reacts with an anti-ubiquitin antibody, which demonstrates that its extra mass results from ubiquitin ligation. Approximately one-seventh of myofibrillar actin is stably ubiquitinated, suggesting that there may be one arthrin molecule per actin-tropomyosin-troponin cooperative unit. Arthrin formation lags several hours behind that of actin III, implying that ubiquitination coincides with some aspect of myofibril assembly.

Actins↗
PubMed1987

Regulation of protein kinase C by cyclic adenosine 3':5'-monophosphate and a tumor promoter in skeletal myoblasts.

The specific activity of protein kinase C in rat skeletal myoblasts decreased when they were exposed for very short periods to isoproterenol, forskolin, dibutyryl cyclic AMP (Bt2cAMP), or the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA). In the presence of Bt2cAMP or forskolin only the cytosolic but not the membrane-bound kinase activity was found to decrease. Treatment with TPA, however, led to a decrease in the activity of the enzyme both in the cytosolic as well as the membrane fractions. The effects observed in vivo could be duplicated in crude extracts of myoblasts incubated with cAMP analogues or TPA. In the presence of ATP, protein kinase C activity decreased considerably in crude cytosolic fractions treated with the cAMP analogues, but a requirement for ATP was not evident for the decrease in activity brought about by TPA. For the cAMP analogues the decrease in protein kinase C was also prevented by incubation of the extracts with an inhibitor of cAMP-dependent protein kinase. The regulation of protein kinase C by Bt2cAMP (but not by TPA) was altered in Rous sarcoma virus-transformed myoblasts. It is considered likely that a component affected by cAMP (probably a substrate for cAMP-dependent protein kinase) participates in the regulation of protein kinase C activity, and it is altered in unknown ways in transformed myoblasts.

Animals↗
PubMed1985

Impaired mononuclear-cell proliferation in patients with the acquired immune deficiency syndrome results from abnormalities of both T lymphocytes and adherent mononuclear cells.

Peripheral blood mononuclear cells from patients with acquired immune deficiency syndrome proliferate poorly after stimulation with soluble mitogens. The present study was undertaken to assess the relative contributions of T lymphocytes and of plastic adherent mononuclear cells to the impaired mononuclear cell responses. We employed a four-step separation procedure including terminal depletion using a monocyte-specific monoclonal antibody (61D3) to derive populations of highly purified T cells from patients and from normal subjects. Highly purified T cells proliferated poorly in response to phytohemagglutinin and pokeweed mitogen. The addition of autologous adherent cells to highly purified T cells markedly improved mitogen-driven proliferation in all subjects; however, mononuclear cells from patients with AIDS responded less well than normals (P less than or equal to 0.01) for both phytohemagglutinin and pokeweed. Allogeneic normal adherent cells fully restored both phytohemagglutinin and pokeweed responses in normal highly purified T cells. Adherent cells from patients were comparable to normal adherent cells in phytohemagglutinin-driven proliferation but performed significantly less well when pokeweed was used to stimulate normal highly purified T-cell responders (4308 cpm after coculture with patients' adherent cells vs 8244 cpm after coculture with allogeneic normal adherent cells; P = 0.05). Similarly, when patient's highly purified T cells were stimulated with pokeweed mitogen, control adherent cells functioned substantially better than patient adherent cells (1198 cpm for allogeneic patient adherent cells vs 2324 cpm for normal adherent cells; P = 0.05). Although the addition of normal adherent cells to patients' highly purified T cells significantly improved pokeweed mitogen responses, these values did not reach normal. Suppression by patients adherent cells was not demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1984

Characterization of the vacuolar ATPase activity of the crassulacean-acid-metabolism plant Kalanchoë daigremontiana. Receptor modulating.

Plants performing crassulacean acid metabolism show a large nocturnal accumulation of malic acid in the vacuole of the photosynthetic cells. It has been postulated that an H+-translocating ATPase energizes the transport of malic acid across the tonoplast into the vacuole. In the present work we have characterized the ATPase activity associated with vacuoles of the crassulacean-acid-metabolism plant Kalanchoë daigremontiana and compare it with other phosphohydrolases. Vacuoles were isolated by polybase-induced lysis of mesophyll-cell protoplasts. The vacuoles had a high activity of unspecific acid phosphatase (pH optimum 5.3). The acid phosphatase was strongly inhibited by ammonium molybdate (with 50% inhibition at about 0.5 mmol m-3), but was not completely inhibited even at much higher ammonium-molybdate concentrations. In contrast, the vacuolar ATPase activity, assayed in the presence of 100 mmol m-3 ammonium molybdate, had a pH optimum of 8.0. ATP was the preferred substrate, but GTP, ITP and ADP were hydrolyzed at appreciable rates. The mean ATPase activity at pH 8.0 was 14.5 nmol h-1 (10(3) vacuoles)-1, an average 13% of which was attributable to residual acid-phosphatase activity. Inorganic-pyrophosphatase activity could not be demonstrated unambiguously. The vacuolar ATPase activity was Mg2+-dependent, had an apparent Km for MgATP2- of 0.31 mol m-3, and was 32% stimulated by 50 mol m-3 KCl. Of the inhibitors tested, oligomycin slightly inhibited the vacuolar ATPase activity and diethylstilbestrol and NO-3 were both markedly inhibitory. Dicyclohexylcarbodiimide and tributyltin were also strongly inhibitory. Tributyltin caused a 50% inhibition at about 0.3 mmol m-3. This is taken as evidence that the vacuolar ATPase might function as an H+-translocating ATPase. It is shown that the measured activity of the vacuolar ATPase would be of the right order to account for the observed rates of nocturnal malic-acid accumulation in K. daigremontiana.

Acid Phosphatase↗
PubMed1984

Influence of Applied NaCl on Crassulacean Acid Metabolism and Ionic Levels in a Cactus, Cereus validus.

To determine possible physiological responses to salinity, seedlings of Cereus validus Haworth, a cactus from Salinas Grandes, Argentina, were treated with up to 600 millimolar NaCl for up to 16 days when they were about 9 months old and 100 millimeters tall. Salt stress decreased stem biomass, e.g. it was 19.7 grams for controls and 11.4 grams for plants treated with 400 millimolar NaCl for 14 days. Nocturnal CO(2) uptake in these obligate Crassulacean acid metabolism (CAM) plants was inhibited 67% upon treatment with 400 millimolar NaCl for 14 days (controls, 181 millimoles CO(2) per square meter), while nocturnal accumulation of malate was inhibited 49% (controls, 230 millimoles malate per square meter). The larger accumulation of malate as compared to uptake of atmospheric CO(2) suggests that internal CO(2) recycling occurred during the dark period. Such recycling was lower in the controls ( approximately 20%) than in the NaCl-treated plants ( approximately 50%). The nocturnal increase in malate and titratable acidity depended on the total daily photosynthetically active radiation available; measurements suggest a quantum requirment of 26 photons per malate. As NaCl in the medium was increased to 600 millimolar in daily increments of 50 millimolar, Na and Cl concentrations in the roots increased from about 7 to 100 millimolar, but K concentration in the cell sap remained near 26 millimolar. Concomitantly, concentrations of Na and Cl in the shoots increased from 8 to 17 millimolar and from 1 to 7 millimolar, respectively, while the K concentration increased about 16 to 60 millimolar. In plants maintained for 14 days at 500 millimolar NaCl, the root levels of Na and Cl increased to 260 millimolar, the shoot levels were about 60 millimolar, and the stem bases began to become necrotic. Such Na retention in the roots together with the special possibilities of carbon reutilization given by CAM are apparently survival mechanisms for the temporarily saline conditions experienced in its natural habitat.

Journal Article↗
PubMed1983

Transfusion-associated cytomegalovirus infection and acquired immune deficiency syndrome in an infant.

An infant who received multiple blood transfusions in the neonatal intensive care unit developed a transfusion-associated CMV infection at age 11 weeks and thereafter was noted to have hepatosplenomegaly, mitogen hyporesponsiveness, persistent viruria, an abnormal distribution of T-lymphocyte subpopulations, and poor growth. He has had recurrent opportunistic infections, including Pneumocystis carinii pneumonia. Six donors of blood products received by this infant were investigated; one was found to have chronic lymphadenopathy, weight loss, intermittent diarrhea, lymphopenia, and a profound depression of lymphocytes with a helper/inducer surface phenotype (T4 positive). Family members have an abnormal distribution of T cell subpopulations similar to those reported in asymptomatic homosexuals. The course of disease in our patient suggests that acquired immune deficiency syndrome may be transmitted to young infants via blood products.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Effect of cyanide in dark and light on the membrane potential and the ATP level of young and mature green tissues of higher plants.

The effect of CN(-) and N(2) on the electrical membrane potential (E(m)) was compared with that of CN(-) on the ATP levels in cotyledons of Gossypium hirsutum and in Lemna gibba L. In mature cotton tissue, CN(-) depolarized E(m) to the energy-independent diffusion potential (E(D)) in the dark. In the light E(m) recovered transiently. The same was observed in leaves of Nicotiana, Avena, Impatiens, Kalanchoë, and in Lemna. In contrast, in young cotton cotyledons and tobacco leaves and, to a large extent, in +sucrose-grown Lemna, E(m) was depolarized to E(D) also in the light in a similar way as in the dark.In Lemna grown without sucrose, the energy-dependent component of E(m) was only partially depolarized by CN(-) in dark or light. Cyanide plus salicylhydroxamic acid completely reduced E(m) to E(D), abolished respiration and photosynthesis, and severely diminished the ATP level. This suggests the operation of a CN(-)-insensitive respiration in uninjured Lemna. The initial CN(-)-induced decay of the ATP level in cotton and Lemna was more rapid than the decay of E(m). CN(-)-induced oscillations of the ATP level were followed by similar but slower oscillations of E(m). This supports the view of a general dependence of E(m) on ATP. Discrepancies between inhibitor-induced changes of E(m) and ATP levels are suggested to result from additional regulation of E(m) by the cytoplasmatic pH value.A comparison of E(D) in young and mature cotton cotyledons in the dark and in the light suggests that in growing young cotyledons the different effect of CN(-) in the light is due to a less effective photosynthesis together with high mitochondrial respiration. In Lemna and in mature cotton tissue, E(m) in the light is maintained by noncyclic photophosphorylation and photosystem II, which is only partly inhibited by CN(-), thus resulting in an incomplete depolarization and recovery of E(m). Complete inhibition of photosynthetic O(2) evolution and membrane depolarization by CN(-) plus salicylhydroxamic acid are suggested to result from photooxidation.

Journal Article↗
PubMed1982

Sex differences in the effects of voluntary activity on sucrose-induced obesity.

Sedentary, adult rats of both sexes fed Purina chow and a 32% sucrose solution overate, gained excess weight and had higher Lee Indexes of obesity than control animals fed only Purina chow. The magnitude of these effects was similar in the males and females. Animals of both sexes fed the sucrose diet showed a slower rate of weight loss during food deprivation than the chow controls. Access to an activity wheel led to a reduction in caloric intake and the elimination of obesity in male rats. In the chow fed male rats activity led to a smaller, transient suppression in caloric intake and a slightly lower level of body weight than the sedentary chow controls. Access to activity did not affect body weight in the female rats in either dietary condition. Rather, both active groups of female rats appeared to compensate for the energy cost of voluntary activity by a small increase in food consumption. Long-term exposure to activity was associated with more rapid weight loss during food deprivation in both males and females. These data reveal that high levels of activity and obesity can co-exist when normal female rats are fed a palatable diet but that activity eliminates this form of obesity in the male rat.

Animals↗
PubMed1977

Effects of Water and Turgor Potential on Malate Efflux from Leaf Slices of Kalanchoë daigremontiana.

Malate efflux from leaf cells of the Crassulacean acid metabolism plant Kalanchoë daigremontiana Hamet et Perrier was studied using leaf slices submerged in experimental solutions. Leaves were harvested at the end of the dark phase and therefore contained high malate levels. Water potentials of solutions were varied between 0 and -5 bar using mannitol (a slowly permeating solute) and ethylene glycol (a rapidly permeating solute), respectively. Mannitol solutions of water potentials down to -5 bar considerably reduced malate efflux. The slowly permeating solute mannitol reduces both water potential and turgor potential of the cells. The water potential of a mannitol solution of -5 bar is just above plasmolyzing concentration. Malate efflux in ethylene glycol at -5 bar was only slightly smaller than at 0 bar, and much higher than in mannitol at -5 bar. Tissues in rapidly permeating ethylene glycol would have turgor potentials similar to tissues in 0.1 mm CaSO(4). The results demonstrate that malate efflux depends on turgor potential rather than on water potential of the cells.

Journal Article↗
PubMed1975

Effects of osmotic gradients on vacuolar malic Acid storage: a basic principle in oscillatory behavior of crassulacean Acid metabolism.

Malate synthesis by CO(2) dark fixation and malate accumulation in the vacuoles of leaf slices of Kalanchoë daigremontiana Hamet et Perrier, a plant performing crassulacean acid metabolism, occurs only in external solutions where the osmotic pressure difference between the cells and the medium is low. Conversely, malate loss from the vacuoles depends on a high osmotic pressure difference between the cells and the medium and is observed in media of low osmotic pressure. This suggests that the diurnal oscillations of malate levels in crassulacean acid metabolism leaf cells are regulated by osmotic gradients. These findings support a model which is introduced to explain how the rhythm of crassulacean acid metabolism may function in the intact plant.

Journal Article↗