Hochstetter's frog (Leiopelma hochstetteri) egg,mobile larvae and froglet development

Egg strings and larvae of Hochstetter's frog (Leiopelma hochstetteri) were located at three widely separated North Island sites: in seeps at Brynderwyns in December 2004, in an open pool at Wharerino in March 2009, and in an underground pool near the Kaipawa Track, Coromandel, in late May 2009. Ten egg strings were also laid by captive frogs in water courses at Hamilton Zoo in April 2009. All egg strings held from 11 to 13 eggs. The egg strings laid in the Brynderwyns were regularly observed until metamorphosis was completed in March 2005. Twenty-four swimming larvae emerged from 25 capsules at c. 40 days after discovery, and at least 14 froglets were produced at c. 90 days. All of them developed in darkness, in a 120 ml pool <30 mm deep. The emerged froglets ranged from 9.8 to 10.8 mm snout-vent length. The detection of eggs, larvae and <11 mm froglets indicates that the egg laying period is at least from late September to May.     

Proline Dehydrogenase Regulates Redox State and Respiratory Metabolism in Trypanosoma cruzi

Over the past three decades, L-proline has become recognized as an important metabolite for trypanosomatids. It is involved in a number of key processes, including energy metabolism, resistance to oxidative and nutritional stress and osmoregulation. In addition, this amino acid supports critical parasite life cycle processes by acting as an energy source, thus enabling host-cell invasion by the parasite and subsequent parasite differentiation. In this paper, we demonstrate that L-proline is oxidized to Δ¹-pyrroline-5-carboxylate (P5C) by the enzyme proline dehydrogenase (TcPRODH, E.C. 1.5.99.8) localized in Trypanosoma cruzi mitochondria. When expressed in its active form in Escherichia coli, TcPRODH exhibits a K_m of 16.58±1.69 µM and a V_max of 66±2 nmol/min mg. Furthermore, we demonstrate that TcPRODH is a FAD-dependent dimeric state protein. TcPRODH mRNA and protein expression are strongly upregulated in the intracellular epimastigote, a stage which requires an external supply of proline. In addition, when Saccharomyces cerevisiae null mutants for this gene (PUT1) were complemented with the TcPRODH gene, diminished free intracellular proline levels and an enhanced sensitivity to oxidative stress in comparison to the null mutant were observed, supporting the hypothesis that free proline accumulation constitutes a defense against oxidative imbalance. Finally, we show that proline oxidation increases cytochrome c oxidase activity in mitochondrial vesicles. Overall, these results demonstrate that TcPRODH is involved in proline-dependant cytoprotection during periods of oxidative imbalance and also shed light on the participation of proline in energy metabolism, which drives critical processes of the T. cruzi life cycle.     

Mitochondrial ATP-sensitive K+ channels are redox-sensitive pathways that control reactive oxygen species production

Pharmacological mitochondrial ATP-sensitive K(+) channel (mitoK(ATP)) opening protects against ischemic damage and mimics ischemic preconditioning. However, physiological and pathological signaling events that open this channel are still not fully understood. We found that catalase, which removes H(2)O(2), is capable of reversing the beneficial effects of ischemic preconditioning but not of mitoK(ATP) agonist diazoxide. On the other hand, 2-mercaptopropionylglycine prevented cardioprotection in both cases, suggesting that this compound may present effects other than scavenging of reactive oxygen species. Indeed, 2-mercaptopropionylglycine and a second thiol-reducing agent, dithiothreitol, impair diazoxide-mediated activation of mitoK(ATP) in isolated heart mitochondria. This demonstrates that mitoK(ATP) activity is regulated by thiol redox status. Furthermore, stimulating the generation of endogenous mitochondrial reactive oxygen species or treating samples with H(2)O(2) strongly enhances mitoK(ATP) activity, in a manner probably dependent on redox sensors located in the channel's sulfonylurea receptor. We also demonstrate that mitoK(ATP) channel activity effectively prevents mitochondrial reactive oxygen release. Collectively, our results suggest that mitoK(ATP) acts as a reactive oxygen sensor that decreases mitochondrial free radical generation in response to enhanced local levels of oxidants. As a result, these channels regulate mitochondrial redox state under physiological conditions and prevent oxidative stress under pathological conditions such as ischemia/reperfusion.     

Calorie restriction changes lipidomic profiles and maintains mitochondrial function and redox balance during isoproterenol-induced cardiac hypertrophy

Journal of Physiology and Biochemistry - Typically, healthy cardiac tissue utilizes more fat than any other organ. Cardiac hypertrophy induces a metabolic shift leading to a preferential...     

Exercise Training Restores Cardiac Protein Quality Control in Heart Failure

Exercise training is a well-known coadjuvant in heart failure treatment; however, the molecular mechanisms underlying its beneficial effects remain elusive. Despite the primary cause, heart failure is often preceded by two distinct phenomena: mitochondria dysfunction and cytosolic protein quality control disruption. The objective of the study was to determine the contribution of exercise training in regulating cardiac mitochondria metabolism and cytosolic protein quality control in a post-myocardial infarction-induced heart failure (MI-HF) animal model. Our data demonstrated that isolated cardiac mitochondria from MI-HF rats displayed decreased oxygen consumption, reduced maximum calcium uptake and elevated H₂O₂ release. These changes were accompanied by exacerbated cardiac oxidative stress and proteasomal insufficiency. Declined proteasomal activity contributes to cardiac protein quality control disruption in our MI-HF model. Using cultured neonatal cardiomyocytes, we showed that either antimycin A or H₂O₂ resulted in inactivation of proteasomal peptidase activity, accumulation of oxidized proteins and cell death, recapitulating our in vivo model. Of interest, eight weeks of exercise training improved cardiac function, peak oxygen uptake and exercise tolerance in MI-HF rats. Moreover, exercise training restored mitochondrial oxygen consumption, increased Ca²⁺-induced permeability transition and reduced H₂O₂ release in MI-HF rats. These changes were followed by reduced oxidative stress and better cardiac protein quality control. Taken together, our findings uncover the potential contribution of mitochondrial dysfunction and cytosolic protein quality control disruption to heart failure and highlight the positive effects of exercise training in re-establishing cardiac mitochondrial physiology and protein quality control, reinforcing the importance of this intervention as a non-pharmacological tool for heart failure therapy.     

NITPICK: peak identification for mass spectrometry data

Background  

The reliable extraction of features from mass spectra is a fundamental step in the automated analysis of proteomic mass spectrometry (MS) experiments.     

Nicorandil protects cardiac mitochondria against permeability transition induced by ischemia-reperfusion

Ischemia followed by reperfusion is known to negatively affect mitochondrial function by inducing a deleterious condition termed mitochondrial permeability transition. Mitochondrial permeability transition is triggered by oxidative stress, which occurs in mitochondria during ischemia-reperfusion as a result of lower antioxidant defenses and increased oxidant production. Permeability transition causes mitochondrial dysfunction and can ultimately lead to cell death. A drug able to minimize mitochondrial damage induced by ischemia-reperfusion may prove to be clinically effective. We aimed to analyze the effects of nicorandil, an ATP-sensitive potassium channel agonist and vasodilator, on mitochondrial function of rat hearts and cardiac HL-1 cells submitted to ischemia-reperfusion. Nicorandil decreased mitochondrial swelling and calcium uptake. It also decreased reactive oxygen species formation and thiobarbituric acid reactive substances levels, a lipid peroxidation biomarker. We thus confirm previous reports that nicorandil inhibits mitochondrial permeability transition and demonstrate that nicorandil inhibits this process by preventing oxidative damage and mitochondrial calcium overload induced by ischemia-reperfusion, resulting in improved cardiomyocyte viability. These results may explain the good clinical results obtained when using nicorandil in the treatment of ischemic heart disease.