Colour characteristics of beef longissimus thoracis during early 72 h postmortem.

This study aimed to investigate the characteristics of beef meat colour during the initial 72 h postmortem to assess the possible effects of mitochondria on meat colour development. Bovine longissimus thoracis muscles (n = 5) were collected from one side of carcasses at 0.5, 4, 8, 12, 24, and 72 h postmortem and displayed in air for 6 days to measure colour and detect mitochondrial morphology and function. The results showed that beef had higher L⁎, a⁎, and b⁎ at 24 and 72 h postmortem and less colour change during 6 days of display in comparison with meat from 0.5, 4, and 8 h postmortem. Changes in mitochondrial morphology were observed at 24 and 72 h postmortem. Mitochondria presented a metabolic pattern early postmortem in that the MRA and NADH content did not change. Both the increase in beef colour stability and tissue oxygen consumption were observed within 72 h postmortem.

In-Situ Imaging of Azoreductase Activity in the Acute and Chronic Ulcerative Colitis Mice by a Near-Infrared Fluorescent Probe.

Azoreductase (AzoR) is an essential reductive enzyme which is closely associated with the intestinal disease such as ulcerative colitis (UC). To date, only a few fluorescent probes for detecting AzoR activity in bacteria or cells have been constructed successfully. It is still challenging to design fluorescent probes for in situ monitoring AzoR in vivo. In this paper, a near-infrared (NIR) fluorescent probe (Cy-Azo) based on hemicyanine is designed and synthesized. The emission of the probe is located at 735 nm in the NIR region, which is favorable for its application in vivo. In addition, Cy-Azo shows high sensitivity to AzoR activity with 17-fold fluorescence enhancement and is particularly selective to AzoR over other enzymes, ions, and amino acids. Meanwhile, a possible response mechanism (the azo group in Cy-Azo is reduced by AzoR and cleaved resulting in the production of Cy-NH2) was proposed and verified by HPLC, MS, and theory calculation. In addition, based on low cell cytotoxicity, Cy-Azo is successfully applied in visualizing the activity of AzoR in two cell lines (HCT116 and HepG2 cells) and three types of bacteria (E. coli, S. aureus, and P. aeruginosa). In particular, due to its NIR emission, the probe can monitor AzoR activity in acute and chronic UC mice models. To our knowledge this is the first fluorescent probe for detecting AzoR activity in vivo, which can provide much important information for the diagnosis and treatment of UC.

Lactate-upregulation of lactate oxidation complex-related genes is blunted in left ventricle of myocardial infarcted rats.

Lactate modulates the expression of lactate oxidation complex (LOC)-related genes and cardiac blood flow under physiological conditions, but its modulatory role remains to be elucidated regarding pathological cardiac stress. The present study evaluated the effect of lactate on LOC-related genes expression and hemodynamics of hearts submitted to myocardial infarction (MI). Four weeks after MI or sham operation, isolated hearts of male Wistar rats were perfused for 60 min with Na+-lactate (20 mM). As expected, MI reduced cardiac contractility and relaxation with no changes in perfusion. The impaired cardiac hemodynamics were associated with increased reactive oxygen species (ROS) levels (Sham: 19.3±0.5 vs MI: 23.8±0.3 µM), NADPH oxidase (NOX) activity (Sham: 42.2±1.3 vs MI: 60.5±1.5 nmol·h-1·mg-1) and monocarboxylate transporter 1 (mct1) mRNA levels (Sham: 1.0±0.06 vs MI: 1.7±0.2 a.u.), but no changes in superoxide dismutase (SOD), catalase, NADH oxidase (NADox), and xanthine oxidase activities. Lactate perfusion in MI hearts had no additional effect on ROS levels, NADox, and NOX activity, however, it partially reduced mct1 mRNA expression (MI-Lactate 1.3±0.08 a.u.). Interestingly, lactate significantly decreased SOD (MI-Lactate: 54.5±4.2 µmol·mg-1·min-1) and catalase (MI: 1.1±0.1 nmol·mg-1·min-1) activities in MI. Collectively, our data suggest that under pathological stress, lactate lacks its ability to modulate the expression of cardiac LOC-related genes and the perfused pressure in hearts submitted to chronic MI. Together, these data contribute to elucidate the mechanisms involved in the pathogenesis of heart failure induced by MI.

Lactate-upregulation of lactate oxidation complex-related genes is blunted in left ventricle of myocardial infarcted rats

Lactate modulates the expression of lactate oxidation complex (LOC)-related genes and cardiac blood flow under physiological conditions, but its modulatory role remains to be elucidated regarding pathological cardiac stress. The present study evaluated the effect of lactate on LOC-related genes expression and hemodynamics of hearts submitted to myocardial infarction (MI). Four weeks after MI or sham operation, isolated hearts of male Wistar rats were perfused for 60 min with Na+-lactate (20 mM). As expected, MI reduced cardiac contractility and relaxation with no changes in perfusion. The impaired cardiac hemodynamics were associated with increased reactive oxygen species (ROS) levels (Sham: 19.3±0.5 vs MI: 23.8±0.3 µM), NADPH oxidase (NOX) activity (Sham: 42.2±1.3 vs MI: 60.5±1.5 nmol·h−1·mg−1) and monocarboxylate transporter 1 (mct1) mRNA levels (Sham: 1.0±0.06 vs MI: 1.7±0.2 a.u.), but no changes in superoxide dismutase (SOD), catalase, NADH oxidase (NADox), and xanthine oxidase activities. Lactate perfusion in MI hearts had no additional effect on ROS levels, NADox, and NOX activity, however, it partially reduced mct1 mRNA expression (MI-Lactate 1.3±0.08 a.u.). Interestingly, lactate significantly decreased SOD (MI-Lactate: 54.5±4.2 µmol·mg−1·min−1) and catalase (MI: 1.1±0.1 nmol·mg−1·min−1) activities in MI. Collectively, our data suggest that under pathological stress, lactate lacks its ability to modulate the expression of cardiac LOC-related genes and the perfused pressure in hearts submitted to chronic MI. Together, these data contribute to elucidate the mechanisms involved in the pathogenesis of heart failure induced by MI.

The effect of temperature in the range of -0.8 to 4°C on lamb meat color stability.

This study investigated effects of controlled freezing point storage (CFPS, -0.8°C) on lamb color stability compared with storage at 4°C (control). The muscle samples (n=5) of longissimus thoracis et lumborum from both carcass sides were assigned randomly to the two storage treatments and stored for 10days. The a⁎, b⁎, R630/580 and Chroma values of samples stored in CFPS were significantly higher than that of samples in control from day 2 to day 10 (P<0.05). Higher relative content of oxymyoglobin but lower relative content of metmyoglobin were observed in samples stored in CFPS treatment than those in control over 10days of storage (P<0.05). Meat samples stored in CFPS group had a significantly higher NADH content and metmyoglobin reductase activity than that in control group. In conclusion, ovine muscle stored in CFPS treatment for 10days demonstrated better color stability in comparison with those in 4°C storage.

Activation of protein phosphatase 2A is responsible for increased content and inactivation of respiratory chain complex i induced by all-trans retinoic acid in human keratinocytes.

This study presents the effect of all-trans retinoic acid (ATRA) on cell growth and respiratory chain complex I in human keratinocyte cultures. Keratinocyte treatment results in increased level of GRIM-19 and other subunits of complex I, in particular of their carbonylated forms, associated with inhibition of its enzymatic activity. The results show that in keratinocytes ATRA-promoted phosphatase activity controls the proteostasis and activity of complex I.

Transgenic Mice Overexpressing Human Angiotensin I Receptor Gene Are Susceptible to Stroke Injury.

Hypertension is one of the co-morbid conditions for stroke and profoundly increases its incidence. Angiotensin II (AngII) is shown to be at the center stage in driving the renin angiotensin system via activation of angiotensin 1 receptor (AT1R). This makes the AT1R gene one of the candidates whose differential regulation leads to the predisposition to disorders associated with hypertension. A haplotype block of four SNPs is represented primarily by haplotype-I, or Hap-I (TTAA), and haplotype-II, or Hap-II (AGCG), in the promoter of human AT1R (hAT1R) gene. To better understand the physiological role of these haplotypes, transgenic (TG) mice containing Hap-I and Hap-II of the hAT1R gene in a 166-kb bacterial artificial chromosome (BAC) were generated. Mice received injection of endothelin-1 (1 mg/ml) directly in to the striatum and were evaluated for neurologic deficit scores and sacrificed for analysis of infarct volume and mRNA levels of various proteins. Mice containing Hap-I suffered from significantly higher neurological deficits and larger brain infarcts than Hap II. Similarly, the molecular analysis of oxidant and inflammatory markers in brains of mice showed a significant increase (p < 0.05) in NOX-1 (2.3-fold), CRP (4.3-fold), and IL6 (1.9-fold) and a corresponding reduced expression of antioxidants SOD (60%) and HO1 (55%) in Hap-I mice as compared to Hap-II mice. These results suggest that increased expression of hAT1R rendered Hap-I TG mice susceptible to stroke-related pathology, possibly due to increased level of brain inflammatory and oxidative stress markers and a suppressed antioxidant defense system.

NOX1 mediates chemoresistance via HIF1α/MDR1 pathway in gallbladder cancer.

NADPH oxidase 1 (NOX1) plays a key role in tumorigenesis and metastasis through generating reactive oxygen species (ROS), an important intracellular signaling molecule. However, how it is expressed in gallbladder cancer (GBC) tissue sample and whether it associates with GBC chemoresistance have never been investigated. Our study analyzed the relationship between NOX1 expression and cisplatin-sensitivity both in vivo and in vitro. We found that reduced NOX1 expression promoted cisplatin efficiency in GBC-SD cells, whereas overexpression of which potentially inhibited the sensitivity of cisplatin in SGC-996 cells. Further study into the mechanism we found that increased NOX1 expression elevated intracellular ROS levels, which then activated HIF-1α/MDR1 pathway. These findings established NOX1 a novel accelerant of chemoresistance in GBC, and NOX1-targeted therapeutics might be exploited as a strategy for increasing the efficacy of cisplatin treatment.

GRIM-19 expression is a potent prognostic marker in colorectal cancer.

Retinoid-interferon-induced mortality-19 (GRIM-19), a recently discovered cell death regulatory gene, may function as a tumor suppressor in many human malignancies. However, the expression of GRIM-19 in and its prognostic value for patients with colorectal cancer (CRC) have not been well investigated to date. Here, GRIM-19 expression was measured immunohistochemically in 94 colon samples and by quantitative real-time reverse transcriptase polymerase chain reaction in 15 paired CRC tissues and adjacent normal tissues. The prognostic significance was assessed using Kaplan-Meier survival estimates and log-rank tests. Our results showed that GRIM-19 mRNA and protein levels in adenoma tissues were similar to those in adjacent normal tissues. However, GRIM-19 expression was severely depressed in carcinomas compared to matched normal tissues (P = .000). Additionally, we found GRIM-19 to be located in both the cytoplasm and nucleus in normal tissues but only in the cytoplasm in CRC tissues. Alteration in GRIM-19 expression occurs early in the pathogenesis of CRC; moreover, low GRIM-19 expression was associated with poor tumor differentiation (P = .013), the presence of lymph nodes (P = .000), metastasis to other organs (P = .045) and vascular invasion (P = .010). During a mean period of 40 months follow-up, patients without GRIM-19 had a statistically significantly lower rate of recurrence/metastasis (P < .05) and a shorter overall survival time (P < .01) than the patients with GRIM-19 expression. Taken together, GRIM-19 expression is closely associated with CRC progression and might be a very promising prognostic biomarker for CRC patients.

Trypanothione reductase: a target protein for a combined in vitro and in silico screening approach.

With the goal to identify novel trypanothione reductase (TR) inhibitors, we performed a combination of in vitro and in silico screening approaches. Starting from a highly diverse compound set of 2,816 compounds, 21 novel TR inhibiting compounds could be identified in the initial in vitro screening campaign against T. cruzi TR. All 21 in vitro hits were used in a subsequent similarity search-based in silico screening on a database containing 200,000 physically available compounds. The similarity search resulted in a data set containing 1,204 potential TR inhibitors, which was subjected to a second in vitro screening campaign leading to 61 additional active compounds. This corresponds to an approximately 10-fold enrichment compared to the initial pure in vitro screening. In total, 82 novel TR inhibitors with activities down to the nM range could be identified proving the validity of our combined in vitro/in silico approach. Moreover, the four most active compounds, showing IC50 values of <1 µM, were selected for determining the inhibitor constant. In first on parasites assays, three compounds inhibited the proliferation of bloodstream T. brucei cell line 449 with EC50 values down to 2 µM.

Expression of GW112 and GRIM-19 in colorectal cancer tissues.

PURPOSE: To investigate the expression of GW112 and GRIM-19 in colorectal cancer tissues. METHODS: Immunohistochemistry and semi-quantitative PCR were used to simultaneously detect the levels of expression of GW112 and GRIM-19 in colorectal cancer tissues and normal colorectal tissues in 39 cases. RESULTS: Expression of GW112 protein and mRNA were significantly higher in colorectal cancer tissues than in normal tissues (p<0.05). Expression of GRIM-19 protein and mRNA were significantly lower in colorectal cancer tissues than in normal tissues (p<0.05). GW112 gene mRNA copy number(GAPDH gene mRNA copy number were 0.53 ± 0.21 and 1.81 ± 0.65 in normal colorectal tissues and colorectal cancer tissues respectively, and GRIM-19 gene mRNA copy number/GAPDH gene mRNA copy number were 1.15 ± 0.29 and 1.74 ± 0.0.44 in colorectal cancer tissues and normal colorectal tissues, respectively. Expression of GW112 gene mRNA was significantly higher in colorectal cancer tissues than in normal tissues (p<0.05), and expression of GRIM- 19 gene mRNA was significantly lower in colorectal cancer tissues than in normal tissues (p<0.05). CONCLUSION: High expression of GW112 in colorectal cancer tissues and reduced expression of GRIM-19 in colorectal cancer tissues may be associated with abnormal proliferation of cancer cells and are possibly one of the reasons for development of colorectal cancer, which can provide effective targets for clinical treatment of this disease.

Toward high-throughput screening of NAD(P)-dependent oxidoreductases using boron-doped diamond microelectrodes and microfluidic devices.

Although oxidoreductases are widely used in many applications, such as biosensors and biofuel cells, improvements in the function of existing oxidoreductases or the discovery of novel oxidoreductases with greater activities is desired. To increase the activity of oxidoreductases by directed evolution, a powerful screening technique for oxidoreductases is required. In this study, we demonstrate the utility of boron-doped diamond (BDD) microelectrodes for quantitative and potentially high-throughput measurement of the activity of NAD(P)-dependent oxidoreductases. We first confirmed that BDD microelectrodes can quantify the activity of low concentrations (10-100 pM) of glucose-6-phosphate dehydrogenase and alcohol dehydrogenase with a measuring time of 1 ms per sample. In addition, we found that poisoning of BDD microelectrodes can be repressed by optimizing the pH and by adding l-arginine to the enzyme solution as an antiaggregation agent. Finally, we fabricated a microfluidic device containing a BDD electrode for the first time and observed the elevation of the oxidation current of NADH with increasing flow rate. These results imply that the combination of a BDD microelectrode and microfluidics can be used for high-throughput screening of an oxidoreductase library containing a large number (>10(6)) of samples, each with a small (nanoliter) sample volume.

Antioxidant defences of Spironucleus vortens: Glutathione is the major non-protein thiol.

The aerotolerant hydrogenosome-containing piscine diplomonad, Spironucleus vortens, is able to withstand high fluctuations in O2 tensions during its life cycle. In the current study, we further investigated the O2 scavenging and antioxidant defence mechanisms which facilitate the survival of S. vortens under such oxidizing conditions. Closed O2 electrode measurements revealed that the S. vortens ATCC 50386 strain was more O2 tolerant than a freshly isolated S. vortens intestinal strain (Sv1). In contrast to the related human diplomonad, Giardia intestinalis, RP-HPLC revealed the major non-protein thiols of S. vortens to be glutathione (GSH, 776 nmol/107 cells) with cysteine and H2S as minor peaks. Furthermore, antioxidant proteins of S. vortens were assayed enzymatically and revealed that S. vortens possesses superoxide dismutase and NADH oxidase (883 and 37.5nmol/min/mg protein, respectively), but like G. intestinalis, lacks catalase and peroxidase activities. Autofluorescence of NAD(P)H and FAD alongside the fluorescence of the GSH-adduct in monochlorobimane-treated live organisms allowed the monitoring of redox balances before and after treatment with inhibitors, metronidazole and auranofin. H2O2 was emitted into the exterior of S. vortens at a rate of 2.85 pmol/min/106 cells. Metronidazole and auranofin led to depletion of S. vortens intracellular NAD(P)H pools and an increase in H2O2 release with concomitant oxidation of GSH, respectively. Garlic-derived compounds completely inhibited O2 consumption by S. vortens (ajoene oil), or significantly depleted the intracellular GSH pool of the organism (allyl alcohol and DADS). Hence, antioxidant defence mechanisms of S. vortens may provide novel targets for parasite chemotherapy.

Highly enhanced electrochemiluminescence based on pseudo triple-enzyme cascade catalysis and in situ generation of co-reactant for thrombin detection.

In this work, a novel pseudo triple-enzyme cascade catalysis amplification strategy was employed to fabricate a highly sensitive electrochemiluminescence (ECL) aptasensor for thrombin (TB) detection. The signal amplification of the proposed aptasensor was based on the synergistic catalysis of glucose dehydrogenase (GDH) and hemin/G-quadruplex to generate a co-reactant in situ for the ECL of peroxydisulfate. Gold nanorods (AuNRs) conjugated with GDH and hemin/G-quadruplex were used as the secondary aptamer bioconjugate (TBA II) in this aptasensor. TB was sandwiched between TBA II and a thiol-terminated TB aptamer which self-assembled on the AuNRs-modified electrode. The pseudo triple-enzyme cascade catalysis was completed as follows: firstly, GDH could effectively catalyze the oxidation of glucose to gluconolactone, coupling with the reduction of ß-nicotinamide adenine dinucleotide hydrate (NAD(+)) into ß-nicotinamide adenine dinucleotide hydrogen (NADH). Then, the hemin/G-quadruplex acted as NADH oxidase, could rapidly oxidize NADH into NAD(+) accompanied with the generation of H2O2. Simultaneously, the hemin/G-quadruplex served as the horseradish peroxidase (HRP)-mimicking DNAzyme that further catalyzed the reduction of H2O2 to generate O2in situ. Then the O2 produced acted as the co-reactant of peroxydisulfate, resulting in significant ECL signal amplification and highly sensitive ECL detection. The proposed aptasensor showed a wide linear range of 0.0001-50 nM with a low detection limit of 33 fM (S/N = 3) for TB determination. The present work demonstrated that the novel strategy has great advantages of sensitivity, selectivity and reproducibility, which hold new promise for highly sensitive bioassays applied in clinical detection.

The first latent green fluorophores for the detection of azoreductase activity in bacterial cultures.

An efficient synthesis of original bio-reductive probes suitable for the detection of azoreductases from the fluorescent rhodamine 110 dye is presented. A "turn-on" green fluorescence response upon reduction of the two diazo bonds of these latent fluorophores was observed both in vitro and in the context of bacterial cultures.

Substrains of inbred mice differ in their physical activity as a behavior.

Recent studies strengthen the belief that physical activity as a behavior has a genetic basis. Screening wheel-running behavior in inbred mouse strains highlighted differences among strains, showing that even very limited genetic differences deeply affect mouse behavior. We extended this observation to substrains of the same inbred mouse strain, that is, BALB/c mice. We found that only a minority of the population of one of these substrains, the BALB/c J, performs spontaneous physical activity. In addition, the runners of this substrain cover a significantly smaller distance than the average runners of two other substrains, namely, the BALB/c ByJ and the BALB/c AnNCrl. The latter shows a striking level of voluntary activity, with the average distance run/day reaching up to about 12 kilometers. These runners are not outstanders, but they represent the majority of the population, with important scientific and economic fallouts to be taken into account during experimental planning. Spontaneous activity persists in pathological conditions, such as cancer-associated cachexia. This important amount of physical activity results in a minor muscle adaptation to endurance exercise over a three-week period; indeed, only a nonsignificant increase in NADH transferase+ fibers occurs in this time frame.

Maturity-dependent chilling tolerance regulated by the antioxidative capacity in postharvest cucumber (Cucumis sativus L.) fruits.

BACKGROUND: The aim of the present study was to reveal the effect of fruit maturity on the chilling tolerance of cucumber (Cucumis sativus L.) fruit and the oxidative and antioxidative mechanisms involved. Chinese mini-cucumber (cv. Hangcui-1) fruits were harvested at four developmental stages: Immature (3-8 days after anthesis (DAA)), Mature (9-16 DAA), Breaker (17-22 DAA) and Yellow (35-40 DAA). All fruits were stored at 2 °C for 9 days and rewarmed at 20 °C for 2 days. RESULTS: The chilling injury index declined with advancing fruit maturity. High superoxide anion radical production rate and hydrogen peroxide content were observed in Immature fruits after cold storage and rewarming. Under chilling stress, superoxide dismutase showed an early response. Fruits at earlier maturity stages exhibited higher catalase, ascorbate peroxidase and monodehydroascorbate reductase activities and glutathione content as well as its redox state, and lower peroxidase, dehydroascorbate reductase and glutathione reductase activities and ascorbate content as well as its redox state. CONCLUSION: Fruits at the earlier developmental stage are more susceptible to chilling injury, which is related to increased oxidative stress. High peroxidase activity and ascorbate content and maintenance of the latter's redox state appear critical to the chilling tolerance of cucumber fruits at later developmental stages.

Expression and clinical significance of GRIM-19 in lung cancer.

We investigated the expression of gene associated with retinoid-interferon-induced mortality-19 (GRIM-19) in lung cancer, a recently discovered cell death regulatory gene. Over-expression of GRIM-19 potentially suppresses proliferation and promotes tumor cell apoptosis. However, the expression of GRIM-19 in human lung cancer has not yet been thoroughly investigated. All of the specimens were obtained using CT-guided lung puncture or bronchial biopsy. The expression of GRIM-19 was investigated using immunohistochemistry. The expression level of GRIM-19 was significantly different between lung cancer and lung inflammation. A relatively lower GRIM-19 expression level was also found in small cell lung carcinomas compared to squamous cell carcinoma and adenocarcinoma. No significant difference between GRIM-19 expression in squamous cell carcinoma and adenocarcinoma was determined. Downregulation of GRIM-19 was found in non-small cell lung carcinomas stages III-IV compared to stages I-II, indicating a negative correlation between the expression level of GRIM-19 and the stage of the primary lesion (T). Furthermore, we found GRIM-19 to be primarily located in the cytoplasm in lung inflammation tissues, but located in the nucleus in lung cancer tissues. GRIM-19 expression occurs as an early phenomenon in the pathogenesis of lung cancer. Our study found that GRIM-19 expression in lung cancer is significantly lower compared to lung inflammation, exhibits a relationship with the histological type and clinical stage of lung cancer, and is a suitable target for the development of new lung cancer therapies.

Decolorization of sulfonated azo dye Metanil Yellow by newly isolated bacterial strains: Bacillus sp. strain AK1 and Lysinibacillus sp. strain AK2.

Two different bacterial strains capable of decolorizing a highly water soluble azo dye Metanil Yellow were isolated from dye contaminated soil sample collected from Atul Dyeing Industry, Bellary, India. The individual bacterial strains Bacillus sp. AK1 and Lysinibacillus sp. AK2 decolorized Metanil Yellow (200 mg L(-1)) completely within 27 and 12h respectively. Various parameters like pH, temperature, NaCl and initial dye concentrations were optimized to develop an economically feasible decolorization process. The maximum concentration of Metanil Yellow (1000 mg L(-1)) was decolorized by strains AK2 and AK1 within 78 and 84 h respectively. These strains could decolorize Metanil Yellow over a broad pH range 5.5-9.0; the optimum pH was 7.2. The decolorization of Metanil Yellow was most efficient at 40°C and confirmed by UV-visible spectroscopy, TLC, HPLC and GC/MS analysis. Further, both the strains showed the involvement of azoreductase in the decolorization process. Phytotoxicity studies of catabolic products of Metanil Yellow on the seeds of chick pea and pigeon pea revealed much reduction in the toxicity of metabolites as compared to the parent dye. These results indicating the effectiveness of strains AK1 and AK2 for the treatment of textile effluents containing azo dyes.

Bacterial flavohemoglobin: a molecular tool to probe mammalian nitric oxide biology.

A wide range of mammalian signaling and stress pathways are mediated by nitric oxide (NO), which is synthesized in vivo by the nitric oxide synthase (NOS) family of enzymes. Experimental manipulations of NO are frequently achieved by either inhibition or activation of endogenous NOS or via providing exogenous NO sources. On the contrary, many microbes consume NO via flavohemoglobin (FlavoHb), a highly efficient NO-dioxygenase that protects from nitrosative stress. Here we report a novel resource for studying NO in mammalian cells by heterologously expressing Escherichia coli FlavoHb within a lentiviral delivery system. This technique boosts endogenous cellular consumption of NO, thus providing a simple and efficacious approach to studying mammalian NO biology that can be employed as both a primary experimental and confirmatory tool.