Mg-ATPase Activity Research Articles

The exploration of pasteurization processes and mechanisms of inactivation of Bacillus cereus ATCC 14579 using radio frequency energy

Radio frequency (RF) heating has been utilized to investigate sterilization techniques, but the mechanism of sterilization via RF heating, particularly on Bacillus cereus (B. cereus), has not been thoroughly examined. In this paper, sterilization processes and potential bactericidal mechanisms of B. cereus using RF were investigated. The best heating and sterilization efficiency was achieved at (Electrode gap 130 mm, conductivity of bacterial suspension 0.1 S/m, volume of bacterial suspension 40 mL). Heating a suspension of B. cereus to 90 °C in 80 s using RF reduced the number of viable bacteria by 4.87 logarithms. At the cellular level, there was a significant leakage of nucleic acids and proteins from the bacterial cells. Additionally, the integrity of the cell membrane was severely damaged, with a decrease in ATP concentration of 2.08 mM, Na, K-ATPase activity to 10.7 (U/109 cells), and Ca, Mg-ATPase activity to 11.6 (U/109 cells). At the molecular level, transcriptomics analysis showed that RF heating of B. cereus to 65 °C produced 650 more differentially expressed genes (DEGs) compared with RF heating to 45 °C. The GO annotation analysis indicated that the majority of differentially expressed genes (DEGs) were predominantly associated with cellular components. KEGG metabolic analysis showed enrichment in microbial metabolism in diverse environments, etc. This study investigated the potential bactericidal mechanism of B. cereus using RF, and provided some theoretical basis for the research of the sterilization of B. cereus.

Calcium reduces the effects of cadmium on the responses of biomarkers in freshwater fish (Oreochromis niloticus)

ABSTRACT The hardness of freshwaters varies depending on geographical locations and calcium is the most important element determining water hardness. Thus, the present study focused on responses of oxidative stress biomarkers in the liver and ATPase activities in the gill of freshwater fish (Oreochromis niloticus) after acute and chronic cadmium exposures in differing calcium levels (30, 60 and 120 mg Ca/L). Fish were exposed to Cd for acute (25 µM, 3 days) and chronic (5 µM, 30 days) durations. There were significant (p < 0.05) alterations in the oxidative stress parameters after cadmium exposures. In the liver, activities of catalase and superoxide dismutase increased in both durations, though activities of glutathione peroxidase, glutathione reductase and glutathione S-transferase decreased. Likewise, levels of glutathione and malondialdehyde increased significantly in both durations. In the gill, there were significant decreases in Na,K-ATPase activity and increases in Mg-ATPase activity. However, calcium alone did not cause any alteration (p > 0.05) in the responses of biomarkers. Data also showed that alterations in biomarkers were highest at the lowest calcium levels. Present data emphasised that calcium protected the fish against the toxic effects of cadmium and suggested that metal toxicity varies depending on the chemical quality of waters from different geographical areas.

Simultaneous ocean acidification and warming do not alter the lipid-associated biochemistry but induce enzyme activities in an asterinid starfish

Ocean acidification and warming affect marine ecosystems from the molecular scale in organismal physiology to broad alterations of ecosystem functions. However, knowledge of their combined effects on tropical-subtropical intertidal species remains limited. Pushing the environmental range of marine species away from the optimum initiates stress impacting biochemical metabolic characteristics, with consequences on lipid-associated and enzyme biochemistry. This study investigates lipid-associated fatty acids (FAs) and enzyme activities involved in biomineralization of the tropical-subtropical starfish Aquilonastra yairi in response to projected near-future global change. The starfish were acclimatized to two temperature levels (27 °C, 32 °C) crossed with three pCO2 concentrations (455 μatm, 1052 μatm, 2066 μatm). Total lipid (ΣLC) and FAs composition were unaffected by combined elevated temperature and pCO2, but at elevated temperature, there was an increase in ΣLC, SFAs (saturated FAs) and PUFAs (polyunsaturated FAs), and a decrease in MUFAs (monounsaturated FAs). However, temperature was the sole factor to significantly alter SFAs composition. Positive parabolic responses of Ca-ATPase and Mg-ATPase enzyme activities were detected at 27 °C with elevated pCO2, while stable enzyme activities were observed at 32 °C with elevated pCO2. Our results indicate that the lipid-associated biochemistry of A. yairi is resilient and capable of coping with near-future ocean acidification and warming. However, the calcification-related enzymes Ca-ATPase and Mg-ATPase activity appear to be more sensitive to pCO2/pH changes, leading to vulnerability concerning the skeletal structure.

Discovery of the first unconventional myosin: Acanthamoeba myosin-I.

Having characterized actin from Acanthamoeba castellanii (Weihing and Korn, Biochemistry, 1971, 10, 590-600) and knowing that myosin had been isolated from the slime mold Physarum (Hatano and Tazawa, Biochim. Biophys. Acta, 1968, 154, 507-519; Adelman and Taylor, Biochemistry, 1969, 8, 4976-4988), we set out in 1969 to find myosin in Acanthamoeba. We used K-EDTA-ATPase activity to assay myosin, because it is a unique feature of muscle myosins. After slightly less than 3years, we purified a K-EDTA ATPase that interacted with actin. Actin filaments stimulated the Mg-ATPase activity of the crude enzyme, but this was lost with further purification. Recombining fractions from the column where this activity was lost revealed a "cofactor" that allowed actin filaments to stimulate the Mg-ATPase of the purified enzyme. The small size of the heavy chain and physical properties of the purified myosin were unprecedented, so many were skeptical, assuming that our myosin was a proteolytic fragment of a larger myosin similar to muscle or Physarum myosin. Subsequently our laboratories confirmed that Acanthamoeba myosin-I is a novel unconventional myosin that interacts with membrane lipids (Adams and Pollard, Nature, 1989, 340 (6234), 565-568) and that the cofactor is a myosin heavy chain kinase (Maruta and Korn, J. Biol. Chem., 1977, 252, 8329-8332). Phylogenetic analysis (Odronitz and Kollmar, Genome Biology, 2007, 8, R196) later established that class I myosin was the first myosin to appear during the evolution of eukaryotes.

Adrenergic Receptors in the Mechanism of Regulation of Mitochondrial and Cytoplasmic Enzymes of Cardiomyocytes by Catecholamines.

We studied the role of adrenoceptors in the regulation of activity of mitochondrial and cytoplasmic enzymes in cardiomyocytes by catecholamines and their metabolites. Different types of adrenergic receptors (AR) agonists acting either on both α- and β-AR or selectively on α- or β-AR, as well as quinoid metabolites of catecholamines were used. It was found that the activating effect of β-AR agonist isadrin (isoproterenol) on succinate dehydrogenase of the mitochondria in the heart is prevented by β-adrenergic blockade. The activating effect of dopamine, epinephrine, and isoproterenol on cytochrome C-oxidase and the inhibitory effect of dopamine, norepinephrine, epinephrine, and isoproterenol on Mg-activated ATPase was not mediated by adrenoreceptors. Hormones of the sympathoadrenal system epinephrine, dopamine, norepinephrine, isoproterenol, and catecholamine metabolites (adrenochrome and adrenoxyl) modulating activity of the respiratory chain enzymes of mitochondria in the heart regulate the processes of tissue respiration by transferring mitochondria into a state of "loose" phosphorylation and respiration coupling. Epinephrine as a β-AR agonist increased activity of cytosolic enzymes catalyzing metabolism of purine nucleotides (adenosine deaminase and AMP deaminase), enzymes of antioxidant defense (glutathione peroxidase and catalase), and the level of malondialdehyde and diene conjugates. β-AR blockade with metoprolol abolished the activating effect of epinephrine on glutathione reductase, glutathione peroxidase, and catalase and reduced the level of malondialdehyde and diene conjugates.

Evaluation of the neuroprotective activity of gamma‐benzylidenes digoxin derivatives against brain ischemia

Brain ischemia is one of the diseases with the highest mortality rate today. Among the victims who do not die, most will have some functional disability as a sequel. Currently, tissue plasminogen activator (rt‐PA) is the only pharmacological treatment for ischemia and there are no treatments with neuroprotective effects for this disease. Recently, cardiotonic steroids (CTS) have been shown to promote neuroprotection against ischemia. However, CTS are drugs that have a narrow therapeutic index and their utilization in clinic are restrict. BD‐15 is a new a non‐toxic benzylidine digoxin derivative that was demonstrated to direct increase of the α3‐Na,K‐ATPase activity, and to prevent chemical ischemia in N2a cells model, but it was never tested in a ischemia model in animal. We report here the results of the use of BD‐15 against cognitive damage and neurotoxic actions caused during brain ischemia. Wistar rats were divided in 4 groups (6 animals per group): Control, Control + BD 100 µg/kg treatment, Ischemia and Ischemia + BD‐15 100 µg/kg treatment. Transient brain ischemia was induced with bilateral occlusion of both common carotid arteries for 30 minutes, and after that the animal were followed by three days of reperfusion, with or without BD‐15 treatment (one dose per day IP, 100 µg/kg) and the hippocampus was collected to perform biochemical analysis such as: membrane lipid profile and peroxidation and membrane enzyme activities (PMCA, SERCA, and acetylcholinesterase); histological analysis for infarct volume quantification using TTC dye, and behavioral parameters assessed by the open field behavior test (the parameters evaluated were the number of times the animal changed quadrant, raised its body and presented self‐cleaning behavior and the number of visits to the central quadrants) were also evaluated. In histological analysis, the ischemia provoked a brain tissue damage after 3 days reperfusion, and BD‐15 treatment was able to impair this damage. Ischemia provoked an decrease in the total Na,K‐ATPase activity and an increase of the expression levels of the pump and BD‐15 prevent that changes caused by ischemia. The same profile was found for total PMCA activity and PMCA4 expression levels. BD‐15 was also able to prevent the decrease of activity of SERCA, Mg‐ATPase and acetylcholinesterase caused by ischemia. The membrane lipid peroxidation (thiobarbituric acid reactive substance), was increased in the ischemic group, and again BD‐15 was able to prevent this effect. Regarding the lipid profile, we observed an increase in the content of phospholipids and cholesterol in the ischemic group, and an decrease in the groups treated with BD‐15. The behavioral parameters demonstrated that BD‐15 prevents the motor damage caused by ischemia. In conclusion, BD‐15 is a non‐toxic CTS that demonstrate the prevention of brain damages provoked by ischemia, and appear to promote neuroprotection in animals exposed to global ischemia.

Effects of in vivo exposures to nanoparticles (Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;, CuO, TiO&lt;sub&gt;2&lt;/sub&gt;) on the activities of ATPases in the gill and muscle of freshwater mussel (Unio tigridis)

Mussels are effective bioindicator organisms for aquatic environments. Therefore, they were often used to determine the effects of various xenobiotics in the aquatic systems. There is no study to our knowledge on the in vivo effects of nanoparticles (NPs) on the activities of ATPases in freshwater mussels (Unio tigridis). This work demonstrates the effects of Al$_{2}$O$_{3}$, CuO, and TiO$_{2}$ NPs on Na- ATPase, Ca-ATPase, and Mg-ATPase activities in the gill and muscle of mussels following 14-day exposures to different concentrations of NPs (0, 1, 3, 9 mg/L). Mussels were fed with laboratory cultured algae (Chlorella vulgaris) during the exposures. There was no ouabainsensitive ATPase activity in the tissues of U. tigridis. The activities of Na-ATPase and Ca-ATPase in the gill decreased significantly (p < 0.05), while Mg-ATPase activity increased. However, the activities of all ATPases decreased significantly after NP exposures in the muscle. There were more significant alterations in the gill compared to the alterations in the muscle. The order of NP effects was determined as TiO$_{2}$ > CuO > Al$_{2}$O$_{3}$. There was no significant alteration in algae consumption between control and NP-exposed mussels. The present study reporting the first data on the effects of NPs in U. tigridis demonstrated the sensitivity of mussel physiology towards NP exposures, suggesting further studies to understand better the physiological response of mussels.

Alterations on the Activities of Ion ATPases in the Gill and Muscle of Freshwater Mussel (Unio tigridis) Exposed to Copper

Ion ATPases in the tissues of aquatic animals are sensitive to metal exposures. Mussels are filter-feeding animals and have a sedentary lifestyle that makes them good bio-indicator animals. Thus, the present study was carried out to investigate the effects of copper (0, 30, 90 µg/L) on the activities of Na-ATPase, Mg-ATPase, and Ca-ATPase in the gill and muscle of freshwater mussels (Unio tigridis) in different exposure durations (0, 7, 14, 21 days). Feeding of mussels during the experiments were done with the cultured unicellular algae (Cholorella vulgaris), serving them approximately 300,000 algae/ml. At the end of 21 days of exposure period, no mussel mortality was recorded. Total protein concentrations in the gill and muscle did not change significantly (P>0.05) in any exposure groups. Likewise, control ATPase activities did not alter significantly during different exposure periods. However, ATPase activities in the gill and muscle of mussels altered significantly (P<0.05) following exposure to copper, especially at the higher concentration. Although there were significant increases and decreases in the activity of Mg-ATPase in both tissues, Na-ATPase and Ca-ATPase activities did not fluctuate as there were only significant decreases at the higher exposure concentration. The present data demonstrated that copper at environmentally realistic concentrations was able to alter the activities of ion ATPases in the gill and muscle of mussels and emphasized osmoregulatory stress which mussels might face in waters contaminated with copper.

Protective effects of active compounds from on heart and brain of mice at simulated high altitude.

To investigate the active compounds from on the heart and brain of mice at simulated high altitude.Fifty healthy male adult BALB/c mice were randomly divided into normal control group, hypoxic model group, acetazolamide group, petroleum ether extract of (PESI) group and octacosan group with 10 mice in each group. Acetazolamide group, PESI group and octacosan group were treated with acetazolamide PESI (200 mg/kg) or octacosan by single tail vein injection, respectively. Except normal control group, the mice were exposed to a simulated high altitude of for in an animal decompression chamber. After the mice were sacrificed by cervical dislocation, the heart and brain were histologically observed by HE staining; superoxide dismutase (SOD) activity, total anti-oxidant capacity (T-AOC) and the content of malondialdehyde (MDA) in plasma, heart and brain tissues were detected by WST-1 method, ABTS method and TBA method, respectively; lactic acid and lactate dehydrogenase (LDH) activity in plasma, heart and brain tissues were detected by colorimetric method and microwell plate method, respectively; ATP content and ATPase activity in heart and brain tissues were detected by colorimetric method. PESI and octacosane significantly attenuated the pathological damages of heart and brain tissue at simulated high altitude; increased SOD activity, T-AOC and LDH activity, and decreased the contents of MDA and lactic acid in plasma, heart and brain tissues; increased the content of ATP in heart and brain tissues; increased the activities of Na-K ATPase, Mg ATPase, Ca ATPase and Ca-Mg ATPase in myocardial tissue; and increased the activities of Mg ATPase, Ca-Mg ATPase in brain tissue. PESI and octacosan exert anti-hypoxic activity by improving the antioxidant capacity, reducing the free radical levels, promoting the anaerobic fermentation, and alleviating the energy deficiency and metabolic disorders caused by hypoxia in mice.

Reconstitution of ATPase Activity from Individual Subunits of the Clathrin-coated Vesicle Proton Pump THE REQUIREMENT AND EFFECT OF THREE SMALL SUBUNITS

The vacuolar-type proton pump of clathrin-coated vesicles is composed of two general domains, a peripheral, catalytic sector (VC) and a transmembranous proton channel (VB). In its native form, the enzyme can hydrolyze both MgATP and CaATP, whereas VC, when separated from VB, loses its MgATPase activity and switches to a state that can hydrolyze only CaATP. Further dissociation of VC results in subcomplexes that are depleted of one or more subunits and lack ATPase activity altogether. Reconstitution of recombinant subunits to these biochemically prepared subcomplexes has demonstrated the necessity of polypeptides of 70, 58, 40, and 33 kDa (subunits A, B, C, and E, respectively) for CaATPase activity of the VC complex. The current studies demonstrate that mixtures of these four recombinant subunits cannot support CaATPase activity in the absence of a biochemically prepared subcomplex. Investigation of the other components required for ATPase activity has led to the identification of three additional polypeptides present in preparations of VC, with apparent molecular masses of 15, 14, and 10 kDa. Each of these proteins was found to activate ATPase activity of mixtures of subunits A, B, C, and E. In addition, ATPase reconstituted from these individual subunits hydrolyses ATP, not only in the presence of Ca2+ but also in the presence of Mg2+. Investigation of the individual properties of these three subunits revealed that the 10-kDa polypeptide is subunit F, as determined by immunoblot analysis. This subunit had no effect on MgATPase activity of VC but stimulated CaATPase activity 6-fold in the presence of subunit D. Under optimal conditions the 14-kDa component resulted in a 10-fold stimulation and the 15-kDa component a 20-fold stimulation of MgATPase activity; based on this observation, the 14- and 15-kDa polypeptides were named subunits G and H, respectively. In addition, proton pumping activity was reconstituted through the reassembly of subunits A-H with VB and SFD, a previously described pump component composed of polypeptides of 50 and 57 kDa (Xie, X.-S, Crider, B.P., Ma, Y. M., and Stone, D. K. (1994) J. Biol. Chem. 269, 25809-25815). Together, these experiments completely define the catalytic center of the vacuolar proton pump of clathrin-coated vesicles.

Defining steps in RAVE-catalyzed V-ATPase assembly using purified RAVE and V-ATPase subcomplexes

The vacuolar H+-ATPase (V-ATPase) is a highly conserved proton pump responsible for the acidification of intracellular organelles in virtually all eukaryotic cells. V-ATPases are regulated by the rapid and reversible disassembly of the peripheral V1 domain from the integral membrane Vo domain, accompanied by release of the V1 C subunit from both domains. Efficient reassembly of V-ATPases requires the Regulator of the H+-ATPase of Vacuoles and Endosomes (RAVE) complex in yeast. Although a number of pairwise interactions between RAVE and V-ATPase subunits have been mapped, the low endogenous levels of the RAVE complex and lethality of constitutive RAV1 overexpression have hindered biochemical characterization of the intact RAVE complex. We describe a novel inducible overexpression system that allows purification of native RAVE and RAVE–V1 complexes. Both purified RAVE and RAVE–V1 contain substoichiometric levels of subunit C. RAVE–V1 binds tightly to expressed subunit C in vitro, but binding of subunit C to RAVE alone is weak. Neither RAVE nor RAVE–V1 interacts with the N-terminal domain of Vo subunit Vph1 in vitro. RAVE–V1 complexes, like isolated V1, have no MgATPase activity, suggesting that RAVE cannot reverse V1 inhibition generated by rotation of subunit H and entrapment of MgADP that occur upon disassembly. However, purified RAVE can accelerate reassembly of V1 carrying a mutant subunit H incapable of inhibition with Vo complexes reconstituted into lipid nanodiscs, consistent with its catalytic activity in vivo. These results provide new insights into the possible order of events in V-ATPase reassembly and the roles of the RAVE complex in each event.

Age, Sex and Overall Health, Measured As Frailty, Modify Myofilament Proteins in Hearts From Naturally Aging Mice

We investigated effects of age, sex and frailty on contractions, calcium transients and myofilament proteins to determine if maladaptive changes associated with aging were sex-specific and modified by frailty. Ventricular myocytes and myofilaments were isolated from middle-aged (~12 mos) and older (~24 mos) mice. Frailty was assessed with a non-invasive frailty index. Calcium transients declined and slowed with age in both sexes, but contractions were largely unaffected. Actomyosin Mg-ATPase activity increased with age in females but not males; this could maintain contractions with smaller calcium transients in females. Phosphorylation of myosin-binding protein C (MyBP-C), desmin, tropomyosin and myosin light chain-1 (MLC-1) increased with age in males, but only MyBP-C and troponin-T increased in females. Enhanced phosphorylation of MyBP-C and MLC-1 could preserve contractions in aging. Interestingly, the age-related decline in Hill coefficients (r = −0.816; p = 0.002) and increase in phosphorylation of desmin (r = 0.735; p = 0.010), tropomyosin (r = 0.779; p = 0.005) and MLC-1 (r = 0.817; p = 0.022) were graded by the level of frailty in males but not females. In these ways, cardiac remodeling at cellular and subcellular levels is graded by overall health in aging males. Such changes may contribute to heart diseases in frail older males, whereas females may be resistant to these effects of frailty.

Slit2 Protects Hearts Against Ischemia-Reperfusion Injury by Inhibiting Inflammatory Responses and Maintaining Myofilament Contractile Properties.

BackgroundThe secreted glycoprotein Slit2, previously known as an axon guidance cue, has recently been found to protect tissues in pathological conditions; however, it is unknown whether Slit2 functions in cardiac ischemia–reperfusion (IR) injury.MethodsLangendorff-perfused isolated hearts from Slit2-overexpressing (Slit2-Tg) mice and C57BL/6J mice (background strain) were subjected to 20 min of global ischemia followed by 40 min of reperfusion. We compared Slit2-Tg with C57BL/6J mice in terms of left ventricular function and infarct size of post-IR hearts along with tissue histological and biochemical assessments (mRNA and protein expression, phosphorylation status, and myofilament contractile properties).ResultsSlit2 played cardioprotective roles in maintaining contractile function and reducing infarct size in post-IR hearts. IR increased the expression of the Slit2 receptor Robo4 and the membrane receptor Slamf7, but these increases were suppressed by Slit2 overexpression post IR. This suppression was associated with inhibition of the nuclear translocation of NFκB p65 and reductions in IL-1β and IL-18 release into perfusates. Furthermore, Slit2 overexpression attenuated the increases in myofilament-associated PKCs and phosphorylation of cTnI at Ser43 in the post-IR myocardium. The myofilament calcium sensitivity and actomyosin MgATPase activity were preserved in the post-IR Slit2 myocardium.ConclusionOur work demonstrates that Slit2 inhibits inflammatory responses and maintains myofilament contractile properties, thus contributing, at least in part, to the prevention of structural and functional damage during IR.

Inosine protects against impairment of memory induced by experimental model of Alzheimer disease: a nucleoside with multitarget brain actions.

Inosine is a naturally occurring purine nucleoside formed by adenosine breakdown. This nucleoside is reported to exert potent effects on memory and learning, possibly through its antioxidant and anti-inflammatory actions. The objective is to evaluate the effects of inosine on the behavioral and neurochemical parameters in a rat model of Alzheimer's disease (AD) induced by streptozotocin (STZ). Adult male rats were divided into four groups: control (saline), STZ, STZ plus inosine (50mg/kg), and STZ plus inosine (100mg/kg). STZ (3mg/kg) was administered by bilateral intracerebroventricular injection. The animals were treated intraperitoneally with inosine for 25days. Memory, oxidative stress, ion pump activities, acetylcholinesterase (AChE), and choline acetyltransferase (ChAT) activities and expression were evaluated in the cerebral cortex and hippocampus. The memory impairment induced by STZ was prevented by inosine. An increase in the Na+, K+-ATPase, and Mg-ATPase activities and a decrease in the Ca2+-ATPase activity were induced by STZ in the hippocampus and cerebral cortex, and inosine could prevent these alterations in ion pump activities. Inosine also prevented the increase in AChE activity and the alterations in AChE and ChAT expression induced by STZ. STZ increased the reactive oxygen species, nitrite levels, and superoxide dismutase activity and decreased the catalase and glutathione peroxidase activities. Inosine treatment conferred protection from these oxidative alterations in the brain. Our findings demonstrate that inosine affects brain multiple targets suggesting that this molecule may have therapeutic potential against cognitive deficit and tissue damage in AD.

Abstract 906: Age-Dependent Modifications in Cardiac Myofilament Proteins are Graded by Overall Health, Measured as Frailty, in Aging Male and Female C57BL/6 Mice

Previously, we showed that the age-dependent decline in ventricular function in male mice is proportional to overall health, as quantified with a frailty index (FI) tool. This tool is based on the accumulation of deficits in health across many systems, but not the cardiovascular system per se . Here we investigated whether frailty grades age-dependent modifications in myofilaments in young and aged mice of both sexes. Myofilaments were isolated from ventricles of adult (12-13 mos; n=5 males, 5 females) and aged (22-23 mos; n=6 males, 5 females) mice. FI scores were obtained from all mice. Actomyosin Mg-ATPase activity as a function of increasing calcium concentration and phosphorylation of major myofilament proteins were quantified and compared between groups. Results showed that myofilament calcium sensitivity (EC 50 values) was similar regardless of age or sex and was not affected by FI score. Maximal actomyosin Mg-ATPase activity increased with age in females, but this was not linked to frailty. Hill coefficients declined with age in males only and were lower than females in the older group (p&lt;0.05). However when all mice were examined, Hill coefficients declined as frailty increased (r=0.68, p=0.001). Total phosphorylation levels of myosin-binding protein C (MyBP-C), desmin, tropomyosin and essential myosin light chain (ELC) increased with age, but only in males. Interestingly, phosphorylation of MyBP-C (r=0.49; p=0.03), desmin (r=0.65; p=0.003), tropomyosin (r=0.62; p=0.004) and ELC (r=0.71; p=0.001) were highly correlated with overall health (FI scores). By contrast there was no link between frailty and phosphorylation of actin, troponin T and troponin I. These findings suggest that poor overall health, quantified in an FI, predicts changes in the myofilaments across the life course in both sexes. This may contribute to changes in cardiac contractile function in frail older adults.

Diurnally Fluctuating pCO2 Modifies the Physiological Responses of Coral Recruits Under Ocean Acidification.

Diurnal pCO2 fluctuations have the potential to modulate the biological impact of ocean acidification (OA) on reef calcifiers, yet little is known about the physiological and biochemical responses of scleractinian corals to fluctuating carbonate chemistry under OA. Here, we exposed newly settled Pocillopora damicornis for 7 days to ambient pCO2, steady and elevated pCO2 (stable OA) and diurnally fluctuating pCO2 under future OA scenario (fluctuating OA). We measured the photo-physiology, growth (lateral growth, budding and calcification), oxidative stress and activities of carbonic anhydrase (CA), Ca-ATPase and Mg-ATPase. Results showed that while OA enhanced the photochemical performance of in hospite symbionts, it also increased catalase activity and lipid peroxidation. Furthermore, both OA treatments altered the activities of host and symbiont CA, suggesting functional changes in the uptake of dissolved inorganic carbon (DIC) for photosynthesis and calcification. Most importantly, only the fluctuating OA treatment resulted in a slight drop in calcification with concurrent up-regulation of Ca-ATPase and Mg-ATPase, implying increased energy expenditure on calcification. Consequently, asexual budding rates decreased by 50% under fluctuating OA. These results suggest that diel pCO2 oscillations could modify the physiological responses and potentially alter the energy budget of coral recruits under future OA, and that fluctuating OA is more energetically expensive for the maintenance of coral recruits than stable OA.

Nanoparticles (Al2O3, CuO, TiO2) Decrease ATPase Activity in the Osmoregulatory Organs of Freshwater Fish (Oreochromis niloticus); Histopathological Investigations of Tissues by Transmission Electron Microscope

The use of nanoparticles (NPs) in diverse field of nanotechnology has been increased in the last decades and especially the aquatic environments have been contaminated by waste products. Because the potential toxic effects of NPs have been documented in different groups of animals, the present study was carried out to help understanding the toxic effects of three NPs in freshwater fish. In this work, Oreochromis niloticus were exposed to aluminum oxide (Al2O3), copper oxide (CuO) and titanium dioxide (TiO2) NPs in differing concentrations (0, 1, 5, 25 mg/L) for 14 d. Following the exposures, the activities of total ATPase, Mg-ATPase and Na, K-ATPase in the osmoregulatory organs (gill, kidney) of fish were measured. Additionally, the aggregates of NPs in the gill and intestine of fish which are the possible entrance to the blood stream were demonstrated by a transmission electron microscope (TEM) to demonstrate the histopathological effects of NPs. Thus, the aim of this study was to evaluate the relationship between the histological view of tissues and changes in ATPase activity. Data showed that all NPs decreased significantly (P 0.05) in ATPase activity in the gill. Overall, data demonstrated that the least affected enzyme was Mg-ATPase and the least toxic NP was Ti-NP. TEM images demonstrated that all NPs accumulated in the tissues of fish in 14 days of exposure period, but not eliminated completely after 14 days of depuration period. There were considerable changes in histological images between control fish tissues and NP exposed fish tissues. NP aggregates in the intercellular space and in the cells can be seen from the TEM images, indicating the decreases in ATPase activities occurred due to histopathological changes. This study demonstrated that NPs are able to cause changes in tissue structures and ATPases were very sensitive to NP exposures. Data suggested that there should be more studies to understand better the toxic effects of NPs in fish.

MgATP hydrolysis destabilizes the interaction between subunit H and yeast V1-ATPase, highlighting H's role in V-ATPase regulation by reversible disassembly

Vacuolar H+-ATPases (V-ATPases; V1Vo-ATPases) are rotary-motor proton pumps that acidify intracellular compartments and, in some tissues, the extracellular space. V-ATPase is regulated by reversible disassembly into autoinhibited V1-ATPase and Vo proton channel sectors. An important player in V-ATPase regulation is subunit H, which binds at the interface of V1 and Vo H is required for MgATPase activity in holo-V-ATPase but also for stabilizing the MgADP-inhibited state in membrane-detached V1 However, how H fulfills these two functions is poorly understood. To characterize the H-V1 interaction and its role in reversible disassembly, we determined binding affinities of full-length H and its N-terminal domain (HNT) for an isolated heterodimer of subunits E and G (EG), the N-terminal domain of subunit a (aNT), and V1 lacking subunit H (V1ΔH). Using isothermal titration calorimetry (ITC) and biolayer interferometry (BLI), we show that HNT binds EG with moderate affinity, that full-length H binds aNT weakly, and that both H and HNT bind V1ΔH with high affinity. We also found that only one molecule of HNT binds V1ΔH with high affinity, suggesting conformational asymmetry of the three EG heterodimers in V1ΔH. Moreover, MgATP hydrolysis-driven conformational changes in V1 destabilized the interaction of H or HNT with V1ΔH, suggesting an interplay between MgADP inhibition and subunit H. Our observation that H binding is affected by MgATP hydrolysis in V1 points to H's role in the mechanism of reversible disassembly.

Smooth muscle-like Ca2+-regulation of actin\u2013myosin interaction in adult jellyfish striated muscle

Cnidaria is an animal phylum, whose members probably have the most ancestral musculature. We prepared and characterized, for the first time to our knowledge, native actomyosin from the striated myoepithelium of the adult moon jelly Aurelia sp. The actomyosin contained myosin, paramyosin-like protein, Ser/Thr-kinase, actin, and two isoforms of tropomyosin, but not troponin, which is known to activate contraction dependent on intracellular Ca2+ signaling in almost all striated muscles of bilaterians. Notably, the myosin comprised striated muscle-type heavy chain and smooth muscle-type regulatory light chains. In the presence of Ca2+, the Mg-ATPase activity of actomyosin was stimulated and Ser21 of the regulatory light chain was concomitantly phosphorylated by the addition of calmodulin and myosin light chain kinase prepared from chicken smooth muscle. Collectively, these results suggest that, similar to smooth muscle, the contraction of jellyfish striated muscle is regulated by Ca2+-dependent phosphorylation of the myosin light chain.

Protective role of heartogen against myocardial infarction in rats

Introduction: Heartogen [HTN], an Ayurvedic medicine is a combination of herbs and bhasmas used in cardiac ailments. Objectives: The present study is aimed at investigating the cardio-protective effects of HTN against isoproterenol [ISP] induced myocardial infarction in rats. Methods: Male rats were pre-treated with HTN [50 and 100mg/kg/day, p.o] or vehicle [0.3% CMC] for 21 days. ISP [120mg/kg, s.c; 2 doses at 24 h interval] was administered on days 19 and 21. On day 22, plasma and heart tissues were collected for biochemical, molecular and histopathological analyses. Results: Pretreatment with HTN significantly reduced plasma CK-MB and cardiac LPO while increased SOD, GSH and GPx levels when compared vehicle treated rats. HTN improved NaKATPase, CaATPase and MgATPase activities in the hearts of ISP intoxicated rats. HTN down-regulated p53, caspase-3 and Bax and up-regulate Bcl2 gene expression. HTN treated rats showed minimal degree of histoarchitectural changes in heart when compared to positive control. Conclusion: Hence, in this manuscript we propose that HTN has the ability to protect against myocardial infarction via anti-oxidant and anti-apoptotic mechanisms.