Changes of Reactive Oxygen Species and Related Enzymes in Mitochondria Respiratory Metabolism During the Ripening of Peach Fruit

The fruits of peach cultivar Yuhua 3 were used as materials to investigate the changes of active oxygen and related enzymes in mitochondria respiratory metabolism during ripening of peach fruit, involving their influence on the proceeding of peach fruit senescence. The results showed that the large decrease in firmness occurred between maturity II and IV. The decrease in firmness coincided with an increase in respiratory intensity. Obvious peaks of respiratory intensity lagging to the rapid change of fruit firmness could be shown during peach ripening. Reactive oxygen species （ROS） had a cumulative process and positively correlated with respiratory intensity. During peach ripening, the content of Ca^2＋ increased, the activities of succinic dehydrogenase （SDH）, cytochrome C oxidase （CCO）, H＋-ATPase, and Ca^2＋-ATPase decreased varying in different degree at the later step of ripening. These suggested a close relationship existed between ROS metabolism and mitochondrial respiration, namely, both ROS metabolism and mitochondrial respiration probably played important roles in ripening and senescing of peach fruit.

Changes of Reactive Oxygen Species and Related Enzymes in Mitochondrial Respiration During Storage of Harvested Peach Fruits

Peach fruits [Prumus persica （L.） Batsch, cv. Yuhuasanhao] were used as materials to investigate the changes of reactive oxygen species （ROS） and related enzymes in mitochondria respiration during storage and then their influence on senescence of harvested Peach fruits was studied. The results showed that low temperature （5℃） strongly inhibited the reduction of firmness and the increase in respiration rate. During storage at ambient temperature （20℃）, ROS had a cumulative process while malondialdehye （MDA） content continued to increase in associated with enhanced membrane lipid peroxidation. Lipoxygenase （LOX） activity was strongly inhibited under the low temperature condition. The activities of succinic dehydrogenase （SDH）, cytochrome C oxidase （CCO）, and Ca^2＋-ATPase declined to a certain extent at ambient temperature, while they showed higher activities at low temperature, which may be related to lower membrane lipid peroxidation at low temperature. Higher Ca^2＋ content at ambient temperature may be responsible for impairment of mitochondrial function, thus, leading to fruit senescence. The results showed that under low temperature condition, the low accumulation of ROS and the low level of membrane lipid peroxidation could maintain the function of mitochondria that would help to delay the senescence of peach fruits. These suggested a close relationship existed between ROS metabolism and mitochondrial respiration. It can be inferred that the low temperature helps to delay senescence of peach fruits via suppression of ROS and related enzymes, maintain better homeostasis of Ca^2＋ in mitochondria and thus better mitochondrial functions.

Mitochondrial energy metabolism changes during aging-mouse cranial nerve cells treated with various doses and forms of Fructus schizandrae

BACKGROUND： During the cellular aging process, the number of mitochondria, generation of adenosine triphosphate （ATP）, activity of respiratory chain enzyme complex 1 and 4, and oxidation decrease. OBJECTIVE： To observe the effects of aqueous and spirituous extract, as well as polysaccharides from Fructus schizandrae （Magnolia Vine） on energy metabolism and mitochondrial anti-oxidation in cranial nerve cells of a D-gal-induced aging mouse model. DESIGN, TIME AND SETTING： A randomized, controlled, animal study. The experiment was conducted at the Department of Biochemistry, Qiqihar Medical College between March and July 2006. MATERIALS： Fifty healthy, Kunming mice of both sexes, aged 2 3 months old and weighing 18 22 g, were used for the present study. Fructus schizandrae was purchased from the Medical College of Jiamusi University. Aqueous extracts, spirituous extracts, and polysaccharides from Fructus schizandrae were prepared. D-galactose （D-gal） is a product of the Second Reagent Factory, Shanghai City, China. Mn-superoxide dismutase （Mn-SOD） kit, malonaldehyde （MDA） kit, protein quantification kit, and inorganic phosphorus testing kit were purchased from Jian Cheng Bioeng. Co., China. METHODS： Fifty mice were randomly divided into five groups, with 10 mice in each group： young control, aging model, aqueous Fructus schizandrae extract, spirituous Fructus schizandrae extract, and Fructus schizandrae polysaccharides. Over a course of 30 days, mice in aging model, aqueous Fructus schizandrae extract, spirituous Fructus schizandrae extract, and Fructus schizandrae polysaccharides groups were injected subcutaneously with D-gal （100 mg/kg） into the nape of the neck daily, and administered intragastrically with an equal volume of sterile, warm water （aging model）, aqueous Fructus schizandrae extract （2 g/kg）, spirituous Fructus schizandrae extract （2 g/kg）, or Fructus schizandrae polysaccharides （0.2 g/kg）, respectively. Mice in the young control group were injected into the nape of the neck with physiological saline and administered intragastrically with sterile, warm water. MAIN OUTCOME MEASURES： Respiratory chain complex I and H^＋-ATP enzyme activities, as well as Mn-SOD and MDA levels, were determined by the Coomassie brilliant blue method. RESULTS： All fifty mice were included in the final analysis. In mitochondria fiom cranial nerve cells of the aging mouse group MDA levels were significantly increased, compared with young control group （P 〈 0.01）; however, Mn-SOD levels, as well as respiratory chain complex I and H＋-ATP enzyme activity, were remarkably decreased （P 〈 0.01 ）. In each Fructus schizandrae group, Mn-SOD levels, as well as respiratory chain complex I and H＋-ATP enzyme activity was enhanced to various extents （P 〈 0.05, P 〈 0.01）, and MDA levels were decreased （P 〈 0.01）, compared with the aging model group. CONCLUSION： Aqueous and spirituous Fructus schizandrae extracts, as well as Fructus schizandrae polysaccharides delayed changes in mitochondrial energy metabolism, increased Mn-SOD levels, and decreased MDA levels in cranial nerve cell mitochondria of an aging mouse model. Fructus schizandrae polysaccharides were particularly capable of protecting mitochondria from oxidative injury.

Adaptation strategies of juvenile grass carp(Ctenopharyngodon idella)facing different dissolved oxygen concentrations in a recirculating aquaculture system

Fishes exposed to different dissolved oxygen concentrations over prolonged time periods have different susceptibility and adaptation mechanisms.In this study,healthy grass carp with an average weight of 214.6±18.7 g were selected for long-term culture in recirculating aquaculture systems at three different dissolved oxygen concentrations,i.e.,3.00 mg/L[(2.57±0.33)mg/L,DO_(2.57)),5.00 mg/L[(4.61±0.11)mg/L,DO_(4.61)],which was the control group,and 7.00 mg/L[(6.50±0.48)mg/L,DO_(6.50)].Blood,gill,muscle,and liver samples were collected after 60 days.Using hematoxylin-eosin(HE),alcian blue periodic acid Schiff(AB-PAS)staining,determination of respiratory metabolism enzyme activity,and fluorescent quantitative PCR,the adaptability of juvenile grass carp facing different dissolved oxygen levels were explored.The results showed that the respiration rate increased,and hemoconcentration and hemoglobin(Hb),electrolyte and pH changed at DO2.57.Furthermore,gill lamellae became thinner and longer,the distance between them increased,the mucus on them decreased and the interstitial cell mass decreased.In addition,the relative expression of apoptosis-related genes bcl-2 and bcl-xl in gill tissue decreased,while caspase-3 and bax increased.In muscles and liver tissues,lactate dehydrogenase(LDH)activity and lactic acid content(LA)increased,pyruvate dehydrogenase(PDH)activity decreased,and genes related to the respiratory metabolic enzymes PDH-A4 and PDH-E1α also changed accordingly.The oxygen consumption rate decreased significantly(P<0.05).At DO_(6.50),the distance between gill lamellae,numbers of red blood cells(RBC)and the content of hemoglobin decreased wheras the mucus on gill lamellae increased.The activity of PDH,the expression of PDH-E1a in liver and oxygen consumption rate increased.Different dissolved oxygen concentrations affected the respiratory behavior,gill tissue structure,blood transport capacity and tissue enzyme activity of juvenile grass carp.In summary,juvenile grass carp showed different adaptation strategies when facing different dissolved oxygen concentrations over prolonged periods in recirculating aquaculture systems.