Long-term safety of early consumption of Lactobacillus fermentum CECT5716: A 3-year follow-up of a randomized controlled trial.

Lactobacillus fermentum CECT5716 is a probiotic strain originally isolated from human breast milk. Previous clinical studies in infants showed that the early administration of a milk formula containing this probiotic strain was safe and may be useful for the prevention of community-acquired infections. This is a 3-year follow-up study aimed at evaluating the long-term effects produced by the early consumption of an infant formula supplemented with L. fermentum CECT5716 (experimental group, EG) compared with a control formula without the probiotic (control group, CG). The infants included in this follow-up study had previously completed a 5-month randomized double-blind controlled trial (from 1 to 6 months of age), where the safety and tolerance of the probiotic formula was evaluated. The main outcome of the follow-up study was the growth of the children. The secondary outcomes included the incidence of infectious and non-infectious diseases, parameters related with intestinal function and faecal microbiota. At 3 years, the mean values of weight, length and head circumference were similar in children of the EG compared with those of the CG. No differences were observed in the incidence of infectious and non-infectious diseases or disorders related with intestinal function. The pattern of faecal microbiota was also similar between both groups. In conclusion, this 3-year study shows that the early administration of the probiotic of L. fermentum CECT5716 in an infant formula is safe and it does not produce measurable differences in children compared with a control formula.

Safety and efficacy of human breast milk Lactobacillus fermentum CECT 5716. A mini-review of studies with infant formulae.

Human breast milk has been described as a source of lactic acid bacteria. Lactobacillus fermentum CECT5716 is a human breast milk strain whose probiotic properties, safety and efficacy has been demonstrated in vitro and in vivo, including controlled trials with human adults. Since the origin of this probiotic strain is human breast milk, we aimed to investigate the safety and efficacy of an infant and a follow-on formulas supplemented with this strain of L. fermentum. We carried out two randomised controlled trials: one trial with infants of 6-12 months of age (follow-on formula study) and another one with infants from 1 to 5 months of age (infant formula study). The results from the trials showed that the probiotic formulas were safe, well tolerated and might be useful for the prevention of community-acquired infections.

Daily consumption of milk enriched with fish oil, oleic acid, minerals and vitamins reduces cell adhesion molecules in healthy children.

BACKGROUND AND AIMS: Several studies have suggested that polyunsaturated fatty acids, vitamins and minerals have beneficial effects on lipid profile and systemic inflammation in adults. METHODS AND RESULTS: We examined the effects of a daily intake of milk enriched with longchain polyunsaturated fatty acids, oleic acid, carbohydrates, vitamins, minerals and low in saturated fatty acids (SFAs) for 5 months, on several cardiovascular (CVD) risk biomarkers in healthy children aged 8-14 years. In a randomized double-blind placebo-controlled trial, a total of 107 children of both genders were assigned to two study groups: 1) a supplemented group (SG, n=53) who consumed 0.6 L/day of an enriched dairy product, and 2) a control group (CG, n=54) who consumed 0.6 L/day of standard whole milk. Both groups consumed the dairy drinks for 5 months, in addition to their usual diet. Serum levels of adhesion molecules as indices of vascular endothelial cell activation were assessed in both groups at 0 and 5 months as well as white blood cell counts, lipid profile, serum proteins, total serum calcium, 25-OH vitamin D, glucose, insulin and adiponectin. In the enriched dairy drink supplemented group, adhesion molecules E-selectin and ICAM-1 as well as lymphocyte levels decreased while plasma docosahexaenoic acid (DHA) and serum calcium concentrations increased. In the control group, serum total protein, transferrin, total cholesterol, HDL-cholesterol and adiponectin concentrations decreased. CONCLUSION: The consumption of a milk enriched with fish oil, oleic acid, minerals and vitamins reduced indices of endothelial cell activation in the studied group of healthy children.

[Intake of an iron-supplemented milk formula as a preventive measure to avoid low iron status in 1-3 year-olds]. / Ingesta de una fórmula láctea suplementada con hierro como medida preventiva del déficit de hierro en niños de 1 a 3 años de edad.

OBJECTIVE: Low iron status is a well known risk factor for iron deficiency anemia in infants and young children. The aim of the present study was to evaluate the influence of an iron-fortified toddler formula on iron status in 1-3 year-olds. PATIENTS AND METHODS: Thirty-three healthy infants and young children were assigned to two groups that received 500 mL/day of and iron-fortified toddler formula or 500 mL/day of unmodified cow's milk for 4 months. Allocation was random and double-blind. Daily dietary intake was calculated by dietary evaluation, and iron nutritional status was assessed (hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, serum iron, ferritin, and transferrin). RESULTS: At enrollment, no anemia was found in either group, although hemoglobin concentration and hematocrit were significantly lower in the toddler formula group than in the unmodified cow's milk group. However, these differences disappeared at the end of the intervention period. After 4 months, the toddler formula group showed significantly higher serum ferritin and lower serum transferrin concentrations than the cow's milk group. CONCLUSION: Intake of iron-supplemented toddler formula for 4 months in 1-3 year-olds is more effective in maintaining iron nutritional status than cow's milk.

Ingesta de una fórmula láctea suplementada con hierro como medida preventiva del déficit de hierro en niños de 1 a 3 años de edad / Intake of an iron-supplemented milk formula as a preventive measure to avoid low iron status in 1-3 year-olds

Objetivo. La baja ingesta de hierro es un factor bien conocido como responsable de anemia por deficiencia de hierro en lactantes y niños pequeños. En el presente estudio se ha evaluado la influencia de la ingesta de una fórmula láctea para niños pequeños suplementada con hierro sobre el estado nutricional del hierro en niños de 1 a 3 años de edad. Pacientes y métodos. Se han estudiado 33 niños sanos distribuidos de forma aleatorizada y doble ciego en 2 grupos, uno que tomó 500 ml/día de una fórmula láctea suplementada con hierro y otro 500 ml/día de leche entera de vaca. Todos los niños tomaron la fórmula o la leche de vaca durante 4 meses. La ingesta de nutrientes fue calculada mediante la valoración de la dieta y se evaluó el estado nutricional del hierro (hemoglobina, hematócrito, volumen corpuscular medio, hemoglobina corpuscular media, concentración de hemoglobina corpuscular media, hierro, ferritina y transferrina). Resultados. Al inicio del estudio, ningún niño presentaba anemia, aunque el grupo que tomó la fórmula láctea suplementada con hierro presentaba una concentración de hemoglobina y hematócrito significativamente más baja. Sin embargo, las diferencias desaparecieron al final del período de intervención. Además, al final del estudio el grupo que tomó la fórmula láctea suplementada con hierro mostró unas concentraciones en suero significativamente más elevadas de ferritina y más bajas de transferrina que el grupo que tomó leche entera de vaca. Conclusión. La ingesta de una fórmula suplementada con hierro para niños pequeños durante 4 meses en niños de 1 a 3 años de edad, contribuye mejor que la leche de vaca a mantener el estado nutricional de hierro

Objective. Low iron status is a well known risk factor for iron deficiency anemia in infants and young children. The aim of the present study was to evaluate the influence of an iron-fortified toddler formula on iron status in 1-3 year-olds. Patients and methods. Thirty-three healthy infants and young children were assigned to two groups that received 500 mL/day of and iron-fortified toddler formula or 500 mL/day of unmodified cow's milk for 4 months. Allocation was random and double-blind. Daily dietary intake was calculated by dietary evaluation, and iron nutritional status was assessed (hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, serum iron, ferritin, and transferrin). Results. At enrollment, no anemia was found in either group, although hemoglobin concentration and hematocrit were significantly lower in the toddler formula group than in the unmodified cow's milk group. However, these differences disappeared at the end of the intervention period. After 4 months, the toddler formula group showed significantly higher serum ferritin and lower serum transferrin concentrations than the cow's milk group. Conclusion. Intake of iron-supplemented toddler formula for 4 months in 1-3 year-olds is more effective in maintaining iron nutritional status than cow's milk

Estudio de las repercusiones clínicas y analíticas de una intervención nutricional en pacientes no hospitalizados con claudicación intermitente. Estudio aleatorio controlado / A study of the clinical and analytical repercussions of a nutritional intervention in non-hospitalised patients with intermittent claudication. A controlled randomised study

Introducción. La dieta es un pilar fundamental, a veces olvidado, en el control y tratamiento de la enfermedad vascular periférica (EVP). Objetivo. Estudiar los efectos de la ingesta de ciertos nutrientes con probado efecto beneficioso en la prevención de la enfermedad coronaria en la clínica y el perfil bioquímico de enfermos claudicantes. Pacientes y métodos. Estudio longitudinal, descriptivo, aleatorio y doble ciego, con 60 varones claudicantes (grado IIB de Fontaine), distribuidos en dos grupos. Grupo I (n = 30): además de su dieta habitual consumieron 500 mL/día de leche semidesnatada adicionada de ácidos eicosapentanoico, docoxahexanoico, oleico y fólico y vitaminas A, D, E y B6. Grupo C (n = 26): además de su dieta habitual consumieron 500 mL/día de leche semidesnatada. Ambos grupos obtuvieron los mismos consejos higienicodietéticos, un antiagregante plaquetario (triflusal) y un hemorreológico (pentoxifilina). Con control trimestral, la intervención duró 12 meses. En cada control se realizó una exploración clínica vascular, claudicometría, índice de Yao, placetismografía y analítica. Resultados. La concentración plasmática de los nutrientes suministrados aumentó en el grupo I (p < 0,05), seguido de un descenso en colesterol total y la concentración de apolipoproteína B. La homocisteína total disminuyó en aquellos pacientes con hiperhomocisteinemia (p < 0,01). Paralelamente, la distancia de claudicación triplicó su valor (p < 0,001) y el índice de Yao aumentó de manera gradual (p < 0,05). Conclusiones. La inclusión diaria en la dieta de ciertos nutrientes cardiosaludables produjo, junto con otras recomendaciones dietéticas y hábitos de vida, una mejora significativa en los parámetros clínicos y analíticos de este grupo de claudicantes. La nutrición puede desempeñar un papel importante en el tratamiento y control de la EVP

INTRODUCTION. Diet is a sometimes neglected cornerstone in the control and treatment of peripheral vascular disease (PVD). AIMS. To study how the intake of certain nutrients with a proven beneficial effect in the prevention of heart disease affects the clinical symptoms and biochemical profile of patients with claudication. PATIENTS AND METHODS. A longitudinal, descriptive, randomised, double-blind study was conducted with 60 males with claudication (Fontaine grade IIB), distributed in two groups. Group I (n = 30): in addition to their usual diet, subjects consumed 500 ml/day of semi-skimmed milk with added eicosapentaenoic, docosahexaenoic, oleic and folic acids, as well as vitamins A, D, E and B6. Group C (n = 26): in addition to their usual diet, subjects consumed 500 mL/day of semi-skimmed milk. Both groups received the same hygienic-dietary guidelines, an antiplatelet drug (triflusal) and a haemorrheologic agent (pentoxifylline). Including a three-monthly control, the intervention lasted 12 months. At each control the following tests were carried out: vascular clinical examination, treadmill exercise testing, Yao index, plethysmography and analyses. RESULTS. The plasma concentration of the nutrients given to patients increased in group I (p < 0.05), followed by a decrease in total cholesterol and apolipoprotein B concentration. The total homocysteine level dropped in patients with hyperhomocysteinemia (p < 0.01). In a parallel fashion, the claudication distance become three times longer (p < 0.001) and the Yao index gradually increased (p < 0.05). CONCLUSIONS. Including certain nutrients that are good for the heart in the daily diet, along with other guidelines concerning nutrition and lifestyle, led to a significant improvement in the clinical and analytical parameters of this group of patients with claudication. Nutrition can play an important role in the treatment and control of PVD

One-month administration of hydroxytyrosol, a phenolic antioxidant present in olive oil, to hyperlipemic rabbits improves blood lipid profile, antioxidant status and reduces atherosclerosis development.

The present study analysed the effects of hydroxytyrosol (HT) on blood lipids, antioxidant status and the progression of aortic lesions in hyperlipemic rabbits. Sixty-four rabbits were distributed into eight groups of animals (n = 8). Animal groups C, A and H were fed for 1-month with a control diet containing sunflower oil (C), an atherogenic diet (A) high in saturated fat and cholesterol or the A diet together with HT, respectively. The other five groups were fed for 2-months with diets C or A (groups CC or AA, respectively), or for 1-month with the A-diet followed by a further month with diet C, extra virgin olive oil diet (O) or diet C with HT (groups AC, AO and AH, respectively). Four milligram of HT/kg body weight were used in the study. Fifty and 42% decrease in total cholesterol and triacylglycerols, respectively, and a 2.3-fold increase in HDL-cholesterol were observed in the AH group but not in the H group. The HT-supplemented groups improved their antioxidant status and reduced the size of atherosclerotic lesions measured as intimal layer areas of the aortic arch when compared with control animals. We conclude that HT supplementation may have cardioprotective effects in vivo.

[Cardiovascular effects of omega-3-fatty acids and alternatives to increase their intake]. / Efectos cardiovasculares de los ácidos grasos omega-3 y alternativas para incrementar su ingesta.

Cardiovascular diseases are the main mortality cause in Europe, the USA and a great extent of Asia. There are several risk factors associated with cardiovascular diseases, such as increased total cholesterol, homocysteine and triglycerides, hypertension, diabetes, and reduced levels of HDL-cholesterol. Many of these risk factors are diet influenced. In spite of the great amount of foods enriched with n-3 fatty acids available at the market, the knowledge about the effects produced by regular intake of these foods still is a challenge in the majority of cases. It appears that intake of foods enriches with n-3 polyunsatured fatty acids is an option that may be effective in reducing risk factors for diseases, by substituting supplements without modifying consumer's alimentary habits. Also shown are the outcomes from a nutritional study undergone with a functional milk-bases food that contains n-3 fatty acids, oleic acid and vitamins.

Efectos cardiovasculares de los ácidos grasos omega-3 y alternativas para incrementar su ingesta / Cardiovascular effects of omega-3-fatty acids and alternatives to increase their intake

Las enfermedades cardiovasculares son la principal causa de mortalidad en Europa, Estados Unidos y gran parte de Asia. Existen varios factores de riesgo asociados a las enfermedades cardiovasculares, entre ellos están el colesterol total, la homocisteína y los triglicéridos elevados, la hipertensión, la diabetes y niveles reducidos de colesterol HDL. Muchos de estos factores de riesgo son influenciables por la dieta. A pesar de la gran cantidad de alimentos enriquecidos en ácidos grasos n-3 disponibles en el mercado, el conocimiento de los efectos originados por el consumo regular de estos alimentos supone aún un reto en la mayoría de los casos. La ingesta de alimentos enriquecidos en ácidos grasos poliinsaturados n-3 parece ser una opción que puede ser eficaz en la reducción de factores de riesgo de enfermedades, sustituyendo a los suplementos sin originar cambios en los hábitos alimentarios del consumidor. También se muestran los resultados procedentes de un estudio nutricional que hemos llevado a cabo con un alimento funcional de base láctea que contiene ácidos grasos n-3, ácido oleico y vitaminas (AU)

Cardiovascular diseases are the main mortality cause in Europe, the USA and a great extent of Asia. There are several risk factors associated with cardiovascular diseases, such as increased total cholesterol, homocysteine and triglycerides, hypertension, diabetes, and reduced levels of HDL-cholesterol. Many of these risk factors are diet influenced. In spite of the great amount of foods enriched with n-3 fatty acids available at the market, the knowledge about the effects produced by regular intake of these foods still is a challenge in the majority of cases. It appears that intake of foods enriches with n-3 polyunsatured fatty acids is an option that may be effective in reducing risk factors for diseases, by substituting supplements without modifying consumer's alimentary habits. Also shown are the outcomes from a nutritional study undergone with a functional milk-bases food that contains n-3 fatty acids, oleic acid and vitamins (AU)

n-3 Fatty acids plus oleic acid and vitamin supplemented milk consumption reduces total and LDL cholesterol, homocysteine and levels of endothelial adhesion molecules in healthy humans.

BACKGROUND AND AIMS: Numerous studies suggest n -3 polyunsaturated fatty acids (n -3 PUFA) and oleic acid intake have beneficial effects on health including risk reduction of coronary heart disease. The purpose of this study was to evaluate the effect of a commercially available skimmed milk supplemented with n -3 PUFA, oleic acid, and vitamins E, B(6), and folic acid (Puleva Omega3) on risk factors for cardiovascular disease. (CVD). METHODS: Thirty volunteers were given 500 ml/day of semi-skimmed milk for 4 weeks and then 500 ml/day of the n -3 enriched milk for 8 further weeks. Plasma and LDL lipoproteins were obtained from volunteers at the beginning of the study (T(pre)), and at 4, 8 and 12 weeks. RESULTS: The consumption of n -3 enriched milk produced a significant decrease in plasma concentration of total and LDL cholesterol accompanied by a reduction in plasma levels of homocysteine. Plasma and LDL oxidability and vitamin E concentration remained unchanged throughout the study. A significant reduction in plasma levels of vascular cell adhesion molecule 1, and an increase in plasma concentration of folic acid were also observed. CONCLUSION: Daily intake of n -3 PUFA and oleic acid supplemented skimmed milk plus folic acid and B-type vitamins has favourable effects on risk factors for CVD.

Stress induces peroxisome biogenesis genes.

Peroxisomes are the cellular location of many antioxidants and are themselves significant producers of reactive oxygen species. In this report we demonstrate the induction of peroxisome biogenesis genes in both plant and animal cells by the universal stress signal molecule hydrogen peroxide. Using PEX1-LUC transgenic plants, rapid local and systemic induction of PEX1-luciferase could be demonstrated in vivo in response to physiological levels of hydrogen peroxide. PEX1-luciferase was also induced in response to wounding and to infection with an avirulent pathogen. We propose a model in which various stress situations that lead to the production of hydrogen peroxide can be ameliorated by elaboration of the peroxisome compartment to assist in restoration of the cellular redox balance.

Biochemical and molecular approaches to understanding protein import into peroxisomes.

Peroxisomes are eukaryotic organelles that perform diverse and variable functions. Although genetic studies in yeasts and mammals have identified approximately 20 genes (PEX genes) required for the biogenesis of this important organelle, biochemical studies of protein targeting and import have lagged behind and in many cases we have no idea of the function of the PEX gene products (peroxins). Using an import assay in vitro derived from sunflower cotyledon cells and recombinant proteins, we have obtained translocation intermediates on the peroxisome import pathway and are using cross-linking to identify interacting partners. We have also used antibodies raised against human PEX14 to inhibit the import of matrix proteins in this system. To obtain homologous antibodies for inhibition experiments, to immunoprecipitate cross-linked products and to enable us to study the import pathways of peroxins we have cloned and characterized plant orthologues of three PEX genes, PEX6, PEX10 and PEX14.

Antibodies against pex14p block ATP-independent binding of matrix proteins to peroxisomes in vitro.

The membrane protein Pex14p is a key component of the protein import machinery of peroxisomes. Antibodies raised against human Pex14p recognise a 66 kDa protein in sunflower glyoxysomes (HaPex14p) and immunoprecipitate in vitro-translated Arabidopsis Pex14p (AtPex14p). These antibodies inhibit the ATP-independent binding to sunflower peroxisome membranes of peroxisome targeting signal type (PTS) 1- and PTS2-targeted matrix proteins, but not an integral membrane protein. These results suggest that Pex14p functions before the ATP-dependent step of peroxisome assembly.

Characterization of membrane polypeptides from pea leaf peroxisomes involved in superoxide radical generation.

The production of superoxide radicals (O2(-).) and the activities of ferricyanide reductase and cytochrome c reductase were investigated in peroxisomal membranes from pea (Pisum sativum L.) leaves using NADH and NADPH as electron donors. The generation of O2(-). by peroxisomal membranes was also assayed in native polyacrylamide gels using an in situ staining method with NitroBlue Tetrazolium (NBT). When peroxisomal membranes were assayed under native conditions using NADH or NADPH as inducer, two different O2(-).-dependent Formazan Blue bands were detected. Analysis by SDS/PAGE of these bands demonstrated that the NADH-induced NBT reduction band contained several polypeptides (PMP32, PMP61, PMP56 and PMP18, where PMP is peroxisomal membrane polypeptide and the number indicates molecular mass in kDa), while the NADPH-induced band was due exclusively to PMP29. PMP32 and PMP29 were purified by preparative SDS/PAGE and electroelution. Reconstituted PMP29 showed cytochrome c reductase activity and O2(-). production, and used NADPH specifically as electron donor. PMP32, however, had ferricyanide reductase and cytochrome c reductase activities, and was also able to generate O2(-). with NADH as electron donor, whereas NADPH was not effective as an inducer. The reductase activities of, and O2(-). production by, PMP32 were inhibited by quinacrine. Polyclonal antibodies against cucumber monodehydroascorbate reductase (MDHAR) recognized PMP32, and this polypeptide is likely to correspond to the MDHAR reported previously in pea leaf peroxisomal membranes.

Purification of catalase from pea leaf peroxisomes: identification of five different isoforms.

Catalase activity was analyzed in seven organs of pea (Pisum sativum L.) plants: leaves, seeds, flowers, shoots, whole fruits, pods and roots. Leaves showed the highest activity followed by whole fruits and flowers. Catalase was purified from pea leaf peroxisomes. These organelles were isolated from leaves by differential and sucrose density-gradient centrifugation, and catalase was purified by two steps involving anion exchange and hydrophobic chromatography using a Fast Protein Liquid Chromatography system. Pure catalase had a specific activity of 953 mmol H2O2 min(-1) mg(-1) protein and was purified 1000-fold, with a yield of about 19 microg enzyme per kg of pea leaves. Analysis by SDS-PAGE and immunoblot showed that the pea catalase was composed of subunits of 57 kDa. Ultraviolet and visible absorption spectra of the enzyme showed two absorption maxima at 252 and 400 nm with molar extinction coefficients of 2.14 x 10(6) and 7.56 x 10(6) M(-1) cm(-1), respectively. By isoelectric focusing (pH 5-7), five different isoforms were identified and designated as CAT1-5, with isoelectric points of 6.41, 6.36, 6.16, 6.13 and 6.09, respectively. All the catalase isoforms contained a subunit of 57 kDa. Post-embedment, EM immunogold labelling of catalase showed a uniform distribution of the enzyme inside the matrix and core of pea leaf peroxisomes.

Characterization of intermediates in the process of plant peroxisomal protein import.

A hybrid protein in which the immunoglobulin G-binding domain of Staphylococcus aureus protein A replaced the N-terminal 43 amino acids of glycolate oxidase (a peroxisomal protein) was affinity purified after expression in Escherichia coli and used to study peroxisomal protein import in vitro. The fusion protein, which co-purifies with the bacterial chaperones dnaK and groEL, binds to glyoxysomes and is partially translocated in an ATP-dependent reaction which is independent of eukaryotic cytosol. Both binding and translocation are dependent upon the amount of glyoxysomes present. The partially translocated species has a transmembrane location and is extractable by salt, indicating that it is held in the membrane by ionic interactions. In the absence of ATP, the fusion protein binds to the surface of the glyoxysomes and competes the binding of authentic matrix proteins. The surface-bound protein can be chased to the transmembrane species upon the addition of ATP. These results indicate that the surface-bound form is a true translocation intermediate. The availability of this fusion protein in milligram quantities offers the possibility to use the intermediate formed in the absence of ATP and the transmembrane species to probe interactions with the peroxisome import machinery.

NADPH is a specific inhibitor of protein import into glyoxysomes.

We have studied the import of proteins into glyoxysomes in vitro and show that this process is specifically inhibited by NADPH. NADPH affects both binding and translocation of proteins into glyoxysomes, and inhibition is determined by the ratio of NADP+ to NADPH. The site of action of NADPH is most likely within the glyoxysome because (1) pretreatment of glyoxysomes with NADPH, followed by re-isolation of the organelles prior to the import assay, resulted in inhibition of import that could be restored by the addition of NADP+; (2) low concentrations of NADPH inhibited binding of proteins to broken glyoxysome membranes. The sensitivity of protein import to inhibition by NADPH declines as glyoxysomes are converted to leaf-type peroxisomes. A model is proposed that speculates on a possible role for NADPH in regulating protein import into plant peroxisomes.

Superoxide radical generation in peroxisomal membranes: evidence for the participation of the 18 kDa integral membrane polypeptide.

Peroxisomes were isolated from pea (Pisum sativum L.) leaves and the peroxisomal membranes were purified by treatment with Na2CO3. The production of superoxide radicals (O2) induced by NADH was investigated in peroxisomal membranes from intact organelles incubated with proteases (pronase E and proteinase K). Under isoosmotic conditions, in the presence of pronase E, the production of O2-. radicals was inhibited by 80%. SDS-PAGE of peroxisomal membranes after protease treatment demonstrated a decrease in the 18-kDa PMP. This suggests that this polypeptide has a small fragment exposed to the cytosolic side of the peroxisomal membrane which is essential for O2-. production. The 18-kDa PMP was purified by preparative SDS-PAGE and in the reconstituted protein the NADH-driven production of O2-. radicals was investigated. The isolated polypeptide showed a high generation rate of superoxide (about 300 nmol O2-. x mg-1 protein x min-1) which was completely inhibited by 50 mM pyridine. The 18-kDa PMP was recognized by a polyclonal antibody against Cyt b5 from human erythrocytes. The presence of b-type cytochrome in peroxisomal membranes was demonstrated by difference spectroscopy. Results obtained show that in the NADH-dependent O2-. radical generating system of peroxisomal membranes, the 18-kDa integral membrane polypeptide, which appears to be Cyt b5, is clearly involved in superoxide radical production.

Immunocytochemical localization of copper,zinc superoxide dismutase in peroxisomes from watermelon (Citrullus vulgaris Schrad.) cotyledons.

In previous works using cell fractionation methods we demonstrated the presence of a Cu,Zn-containing superoxide dismutase in peroxisomes from watermelon cotyledons. In this work, this intracellular localization was evaluated by using western blot and EM immunocytochemical analysis with a polyclonal antibody against peroxisomal Cu,Zn-SOD II from watermelon cotyledons. In crude extracts from 6-day old cotyledons, analysis by western blot showed two cross-reactivity bands which belonged to the isozymes Cu,Zn-SOD I and Cu,Zn-SOD II. In peroxisomes purified by sucrose density-gradient centrifugation only one cross-reactivity band was found in the peroxisomal matrix which corresponded to the isozyme Cu,Zn-SOD II. When SOD activity was assayed in purified peroxisomes two isozymes were detected, Cu,Zn-SOD II in the matrix, and a Mn-SOD in the membrane fraction which was removed by sodium carbonate washing. EM immunocytochemistry of Cu,Zn-SOD on sections of 6-day old cotyledons, showed that gold label was mainly localized over plastids and also in peroxisomes and the cytosol, whereas mitochondria did not label for Cu,Zn-SOD.