Cobia Rachycentron canadum L. reared in low‐salinity water: does dietary sodium chloride affect growth and osmoregulation?

The effects of NaCl supplementation (0.0%, 2.5%, 5.0%, 7.5% and 10.0% dry weight of a basal diet) on growth, gill histological alterations and osmoregulation of juvenile cobia reared in low‐salinity water (5 g L^?1) were assessed. At the end of the experiment, gills were sampled for Na⁺, K⁺‐ATPase activity determination and histological evaluation. In all treatments, no mortality was observed. Results showed that dietary NaCl supplementation did not alter growth. At the highest supplementations (7.5% and 10.0%), juvenile cobia showed higher feed intake and feed conversion ratio. Na⁺, K⁺‐ATPase activity was higher in fish fed the diet without salt supplementation than in those fed with NaCl‐supplemented diets. The number of chloride cells significantly increased with increasing dietary salt level, being 2.5‐fold higher in fish fed with 10.0% NaCl supplementation (41 cells mm^?2) than in those from the non‐supplemented fed group (16 cells mm^?2). These findings indicate that dietary salt supplementation stimulated chloride cell proliferation paralleled with a reduction in the gill Na⁺, K⁺‐ATPase activity, suggesting a possible decrease in energy consumption associated with osmoregulation. However, the suggested energy sparing did not have a significant impact on juvenile cobia growth.     

根系限制对番茄幼苗生长、根系呼吸、ATPase和PPase活性的影响

 采用营养液水培的方式, 研究了根系限制处理对番茄幼苗生长、根系呼吸、质膜和液泡膜上相关酶以及根尖细胞超微结构的影响。结果表明, 在处理初期, 根系限制促进了番茄幼苗根系细胞色素途径呼吸而抑制了交替途径呼吸; 而在后期, 根系限制处理显著地抑制了番茄植株的生长, 对根系的生长抑制更为明显, 且抑制过程伴随着根系总呼吸、细胞色素途径呼吸的降低。此外, 根系限制显著抑制了质膜H⁺ -ATPase, 液泡膜H⁺-ATPase和H⁺ -PPase的活性并导致根尖细胞核的解体。     

The Marine-Derived Macrolactone Mandelalide A Is an Indirect Activator of AMPK

The mandelalides are complex macrolactone natural products with distinct macrocycle motifs and a bioactivity profile that is heavily influenced by compound glycosylation. Mandelalides A and B are direct inhibitors of mitochondrial ATP synthase (complex V) and therefore more toxic to mammalian cells with an oxidative metabolic phenotype. To provide further insight into the pharmacology of the mandelalides, we studied the AMP-activated protein kinase (AMPK) energy stress pathway and report that mandelalide A is an indirect activator of AMPK. Wild-type mouse embryonic fibroblasts (MEFs) and representative human non-small cell lung cancer (NSCLC) cells showed statistically significant increases in phospho-AMPK (Thr172) and phospho-ACC (Ser79) in response to mandelalide A. Mandelalide L, which also harbors an A-type macrocycle, induced similar increases in phospho-AMPK (Thr172) and phospho-ACC (Ser79) in U87-MG glioblastoma cells. In contrast, MEFs co-treated with an AMPK inhibitor (dorsomorphin), AMPKα-null MEFs, or NSCLC cells lacking liver kinase B1 (LKB1) lacked this activity. Mandelalide A was significantly more cytotoxic to AMPKα-null MEFs than wild-type cells, suggesting that AMPK activation serves as a protective response to mandelalide-induced depletion of cellular ATP. However, LKB1 status alone was not predictive of the antiproliferative effects of mandelalide A against NSCLC cells. When EGFR status was considered, erlotinib and mandelalide A showed strong cytotoxic synergy in combination against erlotinib-resistant 11-18 NSCLC cells but not against erlotinib-sensitive PC-9 cells. Finally, prolonged exposures rendered mandelalide A, a potent and efficacious cytotoxin, against a panel of human glioblastoma cell types regardless of the underlying metabolic phenotype of the cell. These results add biological relevance to the mandelalide series and provide the basis for their further pre-clinical evaluation as ATP synthase inhibitors and secondary activators of AMPK.     

盐胁迫下芦荟叶同化组织细胞中ATP酶活性超微结构定位及Si的作用

 利用电镜―细胞化学技术研究了盐胁迫下芦荟（Aloe vera L.）叶同化组织细胞中ATP酶（ATPase）分布特性及外源硅（Si）的作用。结果表明,正常生长情况下,芦荟叶同化组织细胞中液泡膜ATPase活性明显强于质膜ATPase,在细胞壁初生纹孔场观察到很强的ATPase活性。NaCl 100 mmol·L^-1处理30 d,浇灌的营养液中不加可溶性Si,芦荟叶同化组织细胞中液泡膜、质膜和初生纹孔场ATPase活性显著减弱,浇灌的营养液中加Si 2.0 mmol·L^-1处理,芦荟叶同化组织细胞中ATPase活性则显著增强,尤其是在液泡膜和初生纹孔场。叶同化组织细胞中ATPase活性的差异性反映着芦荟叶生理状态和功能的差异性,可溶性Si调节或增强盐胁迫下芦荟ATPase活性是Si缓解芦荟盐胁迫伤害效应的重要细胞生理机制。     

Restoration of cardiac function in failing beagle hearts by recombinant adeno-associated viral gene transfer of sarcoplasmic reticulum Ca2+-ATPase

AIM: Abnormal Ca2+ homeostasis is one basic cause of heart failure. Studies have recently shown that overexpression of sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA2a) by adenoviral/adeno-associated viral gene transfer restores contractile function ex vivo and in murine or rabbit models. We therefore hypothesized that an increase in SERC A2a protein will improve cardiac function in a pacing-induced big animal model of heart failure.METHODS: 17 beagles were randomized into control group (CG, n=4) and chronic heart failure group (n=11). Four weeks after right ventricular rapid pacing (230 beats/min), 11 beagles all got heart failure (documented by >29.3% decrease in ejection fraction). 4 of 11 were used as heart failure group (HF, n=4). 9 HF beagles were randomized to receive either a recombinant adeno-associated viral carrying the SERCA2a gene (HF+SERC A2a, n=5) or the reporter gene enhanced green fluorescent protein (HF+EGFP, n=4) by thoracotomy. All HF beagles paced by 180 beats/min in order to maintain failing state. Thirty days after infection, parameters of systolic and diastolic function were measured by doppler echocardiography and hemodynamic monitor in all beagles.RESULTS: At 30 days after gene transfer, symptoms of HF+SERCA2a dogs improved. Echocardiogram parameters were superior to those in HF+EGFP group (P<0.05). Cardiac hemodynamic parameters of HF+SERCA2a dogs strikingly improved: LVSP, +dp/dtmax and -dp/dtmax increased, mean value increased respectively 54.12％［(214.72±31.74) mmHg vs (139.32±36.79) mmHg］, 146.81％［(6 779.43±217.58) mmHg/s vs (2 746.85±931.2) mmHg/s］ and 71.52％［(-4 341.42±322.02) mmHg/s vs (-2 531.14±616.15) mmHg/s］; LVEDP lowered 63.43％［(21.86±6.95) mmHg vs (59.78±6.92) mmHg］ compared with the dogs in HF+EGFP group. No significant difference in all parameters compared with those of control group was observed. Under laser confocal microscopy, widespread green fluorescence was observed in the myocardial frozen section of dogs in HF+EGFP group. CONCLUSION: These results support the hypothesis that overexpression of SERCA2a improves cardiac function in big animal model of chronic heart failure. The study demonstrates that gene transfer of SERCA2a into cardiac with recombinant adeno-associated viral vector is a prospective therapy methods.     

低钾胁迫对玉米自交系苗期部分光合特性的影响

研究耐低钾玉米自交系在光合特性上的耐低钾机制。玉米自交系种子A(不耐低钾)和B(耐低钾),用3个不同钾离子浓度(5、100、1 000 μmol/L)进行液体培养,4周时将苗转入培养桶中,连续培养50 d。测定其光合速率、荧光效率、PEP羧化酶(PEPase)、ATP酶(ATPase)。结果表明,低钾条件下,自交系B的光合速率、PEPase、ATPase活性显著高于自交系A,荧光效率彼此无显著性差异。因此,低钾条件下,光能转化效率不是光合作用的限制因子,耐低钾自交系通过提高光合作用的暗反应而提高光合作用,从而适应低钾逆境。     

铝胁迫对小麦根呼吸作用和一些线粒体结合酶活性影响

比较了耐铝性不同的两品种小麦Altas66和Scout66根呼吸速率、线粒体H+-ATP酶、Ca2+-ATP酶和焦磷酸酶活性变化.铝处理后,两品种小麦根呼吸速率均下降,随处理铝浓度增加而加剧,但对照和处理条件下,Altas66根呼吸速率均高于Scout66.两品种小麦根线粒体膜上都存在H+-ATP酶、Ca2+-ATP酶和H+-PP酶,离体和活体铝处理后,这些酶活性受     

小麦雄性不育系和保持系花药ATP酶细胞色素氧化酶细胞化学定位

本文运用电子显微镜细胞化学标记技术,对K型雄性不育系和其保持系小麦花药各个组织中的细胞色素氧化酶和ATP酶活性进行了定位,相对定量研究。结果表明,药壁四层组织和药隔细胞中两种酶的活性分布在花粉粒败育前,不育系与其保持系之间几乎没有差别,均在细胞核、核仁、质膜与胞间连丝中有ATP酶的活性,线粒体内嵴上有细胞     

光敏胞质不育小麦花药发育过程中ATP酶的定位研究

采用磷酸铅沉淀法(酶孵育离子为Mg2+)研究了不同日照条件下光敏胞质不育 小麦花药发育过程中ATPase分布的变化。 结果表明： 短日照条件下花粉可育, 单核早 期ATPase主要分布在花粉表面和细胞核中, 花粉外壁、 质膜及细胞质中有少量的ATPas e 分布; 随着花粉的发育, 其表面、 外壁、 内壁、 质膜及细胞质内ATPase进一步增