Trichoderma asperellum Induces Maize Seedling Growth by Activating the Plasma Membrane H+-ATPase.

Although Trichoderma spp. have beneficial effects on numerous plants, there is not enough knowledge about the mechanism by which they improves plant growth. In this study, we evaluated the participation of plasma membrane (PM) H+-ATPase, a key enzyme involved in promoting cell growth, in the elongation induced by T. asperellum and compared it with the effect of 10 µM indol acetic acid (IAA) because IAA promotes elongation and PM H+-ATPase activation. Two seed treatments were tested: biopriming and noncontact. In neither were the tissues colonized by T. asperellum; however, the seedlings were longer than the control seedlings, which also accumulated IAA and increased root acidification. An auxin transport inhibitor (2,3,5 triiodobenzoic acid) reduced the plant elongation induced by Trichoderma spp. T. asperellum seed treatment increased the PM H+-ATPase activity in plant roots and shoots. Additionally, the T. asperellum extracellular extract (TE) activated the PM H+-ATPase activity of microsomal fractions of control plants, although it contained 0.3 µM IAA. Furthermore, the mechanism of activation of PM H+-ATPase was different for IAA and TE; in the latter, the activation depends on the phosphorylation state of the enzyme, suggesting that, in addition to IAA, T. asperellum excretes other molecules that stimulate PM H+-ATPase to induce plant growth.

[Functional disorders of FOF1-ATPase in submitochondrial particles obtained from platelets of patients with a diagnosis of probable Alzheimer's disease]. / Alteración funcional de la F0F1-ATPasa en partículas submitocondriales obtenidas de plaquetas de pacientes con diagnóstico de enfermedad de Alzheimer probable.

INTRODUCTION: Recent studies indicate that decreased energy generation by mitochondria is a feature that is common across neurodegenerative diseases. PATIENTS AND METHODS: In order to obtain direct evidence that mitochondrial functioning is altered, we measured the hydrolytic activity of F0F1-ATPase and its capacity to generate a stable proton gradient in submitochondrial particles in 29 patients diagnosed with probable Alzheimer's disease (AD). Submitochondrial particles were obtained from platelets of patients with a diagnosis of probable AD and from clinically healthy controls. RESULTS: Data revealed that the hydrolytic activity of F0F1-ATPase increases significantly in patients with probable AD (41.7+/-4.3 nmol PO4 min-1[mg protein]-1, n=29) as compared to the control subjects (29.1+/-1.9 nmol PO4 min-1 [mg protein]-1, n=29). It is important to note that, in the male population with probable AD, we found that hydrolytic activity of F0F1-ATPase increased as cerebral deterioration progressed. We also detected a lower pH gradient in the submitochondrial particles of patients with probable AD (0.28+/-0.08 pH units, n=25) as compared to the controls (0.5+/-0.1 pH units, n=20). CONCLUSIONS: Overall, these data point to an alteration in the functioning of the enzyme.

Alteración funcional de la F0F1-ATPasa en partículas submitocondriales obtenidas de plaquetas de pacientes con diagnóstico de enfermedad de Alzheimer probable / Functional disorders of fof1-atpase in submitochondrial particles obtained from platelets of patients with a diagnosis of probable alzheimer’s disease

Introducción. Los estudios recientes indican que una disminución en la generación de energía de la mitocondria es una característica que unifica a las enfermedades neurodegenerativas. Pacientes y métodos. Para obtener evidencia directa que la función mitocondrial se altera, cuantificamos en 29 pacientes diagnosticados con probable enfermedad de Alzheimer (EA) la actividad hidrolítica de la F0F1-ATPasa y su capacidad para generar un gradiente estable de protones en partículas submitocondriales. Las partículas submitocondriales se obtuvieron de plaquetas de pacientes con diagnóstico probable de EA y de controles clínicamente sanos. Resultados. Los datos revelaron que la actividad hidrolítica de la F0F1-ATPasa se incrementa de manera significativa en los pacientes con la probable EA -41,7 ± 4,3 nmol PO4 min-1(mg proteína)-1, con n = 29- en comparación con los controles -29,1 ± 1,9 nmol PO4 min-1 (mg proteína)- 1, con n = 29-. De manera importante, encontramos que en la población masculina con probable EA, la actividad hidrolítica de la F0F1-ATPasa aumenta conforme progresa el deterioro cerebral. También detectamos un gradiente de pH menor en las partículas submitocondriales de los pacientes con probable EA (0,28 ± 0,08 unidades de pH, n = 25) comparados con los controles (0,5 ± 0,1 unidades de pH, n = 20). Conclusión. Estos datos, en conjunto, indican una alteración funcional en la enzima

Introduction. Recent studies indicate that decreased energy generation by mitochondria is a feature that is common across neurodegenerative diseases. Patients and methods. In order to obtain direct evidence that mitochondrial functioning is altered, we measured the hydrolytic activity of F0F1-ATPase and its capacity to generate a stable proton gradient in submitochondrial particles in 29 patients diagnosed with probable Alzheimer’s disease (AD). Submitochondrial particles were obtained from platelets of patients with a diagnosis of probable AD and from clinically healthy controls. Results. Data revealed that the hydrolytic activity of F0F1-ATPase increases significantly in patients with probable AD (41.7 ± 4.3 nmol PO4 min-1[mg protein]-1, n = 29) as compared to the control subjects (29.1 ± 1.9 nmol PO4 min-1 [mg protein]-1, n = 29). It is important to note that, in the male population with probable AD, we found that hydrolytic activity of F0F1-ATPase increased as cerebral deterioration progressed. We also detected a lower pH gradient in the submitochondrial particles of patients with probable AD (0.28 ± 0.08 pH units, n = 25) as compared to the controls (0.5 ± 0.1 pH units, n = 20). Conclusions. Overall, these data point to an alteration in the functioning of the enzyme

Comparison of plasma membrane H+-ATPase activity in vesicles obtained from dry and hydrated maize embryos.

ATP hydrolysis from H+-ATPase of plasma membrane was measured in vesicles from maize embryos imbibed at times between 0 and 5 h. The activity had a maximum at 2 h of imbibition. In order to detect whether the enzyme had the same characteristics through the first 5 h of imbibition, vanadate and lysophophatydilcholine sensitivities, as well as trypsin, pH and temperature effects on the activity of the H+-ATPase from plasma membrane vesicles isolated from embryos imbibed at 0 or 5 h were studied. The results indicate that the activity expressed at 0 h is very different from the activity at 5 h. The activity from embryos imbibed for 5 h was less sensitive to vanadate, trypsin and lysophosphatidylcholine, more sensitive to denaturing temperatures and with a broader pH dependence, as compared to the activity from embryos that were not imbibed. When vanadate-sensitive ATPase activity was purified by anion exchange chromatography, the peaks obtained from the 0 and 5 h imbibed embryos were different and non-overlapping. These data could be interpreted in terms of different enzyme structures from dry and imbibed embryos due to either different primary structures or covalent modifications, or differences in membrane vicinities.

A modified colorimetric method for the determination of orthophosphate in the presence of high ATP concentrations.

We describe a modified colorimetric method that quantitates inorganic phosphate linearly up to 60 nmol, with high stability of the developed color and with a low interference by ATP concentration (up to 30 mM). This method is very suitable for use in ATPase enzymatic assays, especially with enzymes that have low specific activities and (or) high Km values for ATP.

Effect of diacetyl piquerol on H(+)-ATPase activity of microsomes fromIpomoea purpurea.

The effect of an allelopathic compound, diacetyl-piquerol on the H(+) -ATPase activity of the microsomal fraction from the radicles of a common weedIpomoea purpurea was studied. The diacetyl-piquerol inhibited the germination and radicle growth fromI. purpurea; the radicle growth was increasingly inhibited (10% to 100%) as piquerol concentrations were raised (10 µM to 1000 µM). The H(+)-ATPase activity was inhibited (48%) by 500 µM diacetyl-piquerol, and this inhibition was higher in plasma membrane ATPase (67.2%) than in tonoplast membrane ATPase (31.4%). Additional studies of the precise physiological mechanisms of interference caused by allelopathic compounds are needed.