Translocation of cholesterol from leaves to ripening fruits of Solanum khasianum

After foliar application of [4-¹⁴C]cholesterol to a Solanum khasianum shrub during a 6-week period, cholesterol was recovered not only from untreated leaves, but also from fruits at three different stages of maturity. In addition to free [4-¹⁴C]cholesterol, small amounts of [4-¹⁴C]cholesteryl esters but no [4-C¹⁴]cholesteryl glycosides were found in the fruits, treated, and untreated leaves. Thus, cholesteryl glycosides are probably not involved in the translocation of cholesterol. The implications of cholesterol translocation in the kinetics of solasodine Production are discussed.     

叉头转录因子1基因FOXO1的特征及其在葱蝇夏滞育前期蛹体内糖脂代谢中的作用(英文)

【目的】克隆和鉴定葱蝇Delia antiqua叉头转录因子1基因,探究其在葱蝇夏滞育前期蛹体内糖代谢和脂代谢中的作用。【方法】本研究基于葱蝇转录组数据利用3′RACE法克隆叉头转录因子1基因的全长开放阅读框;利用生物信息学法分析了该基因编码蛋白的序列特征、保守结构域和二级结构,并采用最大似然法对其与其他13种昆虫来源的同源序列进行了聚类分析。通过RNA干扰技术沉默目的基因后,采用实时定量PCR法分析葱蝇夏滞育前期蛹体内目的基因下游脂肪酶brummer基因(DaBmm)和磷酸烯醇式丙酮酸羧化酶基因(DaDepck)的表达规律,并对甘油三脂(TAG)、海藻糖和葡萄糖含量及总脂肪酶的活性变化进行分析。【结果】克隆得到了葱蝇叉头转录因子1基因DaFOXO1 (GenBank登录号: MG813258),其编码蛋白含有619个氨基酸,具有典型的叉头DNA结合域,核定位信号,2个14-3-3结合区和1个富含谷氨酰胺区;DaFOXO1与铜绿蝇Lucilia cuprina FOXO1蛋白的氨基酸序列有87%的一致性,并与其聚为一支。干扰葱蝇夏滞育前期蛹DaFOXO1后,8-20 h间可显著抑制DaBmm基因的表达,12-24 h间可显著影响TAG含量和总脂肪酶的活性,8-20 h(16 h除外)间可显著降低DaPepck的表达,但对葡萄糖和海藻糖的含量没有显著影响。【结论】本研究结果表明海藻糖和葡萄糖的积累在化蛹前已完成;DaFOXO1对DaBmm和DaDepck基因的表达调控可能有利于葱蝇夏滞育前期蛹体内的脂肪积累。同时也表明靶向Bmm依赖性脂类水解过程及其下游因子可为打破昆虫滞育提供一种有效策略。     

Genetic diseases of the Kennedy pathways for membrane synthesis

The two branches of the Kennedy pathways (CDP-choline and CDP-ethanolamine) are the predominant pathways responsible for the synthesis of the most abundant phospholipids, phosphatidylcholine and phosphatidylethanolamine, respectively, in mammalian membranes. Recently, hereditary diseases associated with single gene mutations in the Kennedy pathways have been identified. Interestingly, genetic diseases within the same pathway vary greatly, ranging from muscular dystrophy to spastic paraplegia to a childhood blinding disorder to bone deformations. Indeed, different point mutations in the same gene (PCYT1; CCTα) result in at least three distinct diseases. In this review, we will summarize and review the genetic diseases associated with mutations in genes of the Kennedy pathway for phospholipid synthesis. These single-gene disorders provide insight, indeed direct genotype-phenotype relationships, into the biological functions of specific enzymes of the Kennedy pathway. We discuss potential mechanisms of how mutations within the same pathway can cause disparate disease.     

夜间低温胁迫对两种生长光强下藤黄幼苗叶片荧光特征和活性氧代谢的影响

对两种不同生长光强下（自然光的8％和50％）西双版纳热带雨林木本植物藤黄（Garcinia han-buryi）幼苗经夜间低温（4℃）处理后荧光特性和活性氧代谢的研究结果表明,低温使藤黄叶片光合机构PSⅡ原初光能转化效率（Fv/Fm）、PSⅡ非环式电子传递的量子效率（ФPSⅡ）、非光化学猝灭系数（NPQ）下降,原初荧光（F0）上升。低温胁迫消除后,生长在50％光强下藤黄叶片的Fv/Fm和F0在3d后仍不能完全恢复,而生长在8％光强下藤黄叶片的Fv/Fm和F0基本恢复,说明低温使生长在8％光强下藤黄的光合机构PSⅡ反应中心受到可逆失活,而生长在50％光强下藤黄的光合机构受到氧化伤害。随着低温胁迫时间的延长,两种生长光强藤黄叶片活性氧保护酶（SOD,CAT,APX）的活性虽升高,但O2^-的生成速率、H2O2和MDA含量积累增加。而在恢复阶段,生长在8％光强比生长在50％光强下藤黄叶片的活性氧含量下降得快,进一步说明生长在高光强的植物比生长在低光强的植物受低温伤害大。     

Carbohydrate energy metabolism in Fasciola gigantica (trematoda)

Umezurike G. M. and Anya A. O. 1980. Carbohydrate energy metabolism in Fasciola gigantica (Trematoda). International Journal for Parasitology10: 175–180. Adult Fasciola gigantica contained 4.49 ± 0.06 % (mean ± S.D.) wet weight glycogen. Tissue homogenates contained high levels of malate dehydrogenase (MDH), NAD-linked malic enzyme (ME), Phosphoenolpyruvate carboxykinase (PEPCK) and lactate dehydrogenase (LDH). MDH, PEPCK and ME activities appeared to be localized in both cytosolic and mitoehondrial fractions, fumarase activity appeared to be predominantly mitochondrial whereas LDH and pyruvate kinase activities were cytosolic in distribution. Polyacrylamide gel electrophoresis revealed the predominance of LDH-1, LDH-2 and LDH-3 but only traces of LDH-4 and LDH-5 isoenzymes in the crude cytosolic fraction. LDH activity in the crude sample was inhibited by excess substrate (pyruvate). The mitoehondrial system showed NADH -cytochrome c oxidoreductase, succinate-cytochrome c oxidoreductase, NADH oxidase and some cytochrome c-oxygen oxidoreductase activities. Under anaerobic conditions, NADH-fumarate oxidoreductase and succinate-NAD + oxidoreductase activities of mitoehondrial preparations were stimulated in the presence of ADP and ATP respectively. Isolated mitochondria contained rhodoquinone and no ubiquinone, and isolated rhodoquinone was readily reduced by succinate in the presence of submitochondrial particles. Hydrogen peroxide was produced by submitochondrial particles in the presence or absence of KCN or in the presence of fumarate.     

西那卡塞联合碳酸司维拉姆对血液透析并发继发性甲状旁腺功能亢进患者钙磷代谢、FGF23/Klotho轴和心血管事件的影响

摘要 目的：观察西那卡塞联合碳酸司维拉姆对血液透析并发继发性甲状旁腺功能亢进（SHPT）患者钙磷代谢、成纤维细胞生长因子23（FGF23）/Klotho轴和心血管事件的影响。方法：选取2018年3月-2020年5月新疆医科大学第一附属医院收治的200例血液透析并发SHPT患者,根据随机数字表法分成观察组（n=100）与对照组（n=100）。对照组患者接受碳酸司维拉姆治疗,观察组患者接受西那卡塞联合碳酸司维拉姆治疗,两组患者均连续治疗3个月。观察两组疗效以及钙磷代谢指标、全段甲状旁腺激素（iPTH）、甲状旁腺体积、FGF23、Klotho水平变化,记录治疗期间发生的心血管事件。结果：观察组的临床总有效率较对照组高（P<0.05）。治疗后两组血钙升高,血磷、钙磷乘积下降（P<0.05）,且观察组治疗后血钙较对照组高,血磷、钙磷乘积较对照组低（P<0.05）。两组治疗后血清iPTH水平下降,甲状旁腺体积缩小,且观察组的变化程度较对照组大（P<0.05）。两组治疗后Klotho水平升高,FGF23水平下降,且观察组的变化程度大于对照组（P<0.05）。观察组的非致死性心血管事件发生率明显低于对照组（P<0.05）。结论：西那卡塞联合碳酸司维拉姆治疗血液透析并发SHPT患者疗效显著,可调节钙磷代谢,降低血清iPTH水平,缩小甲状旁腺体积,调节Klotho、FGF23水平,降低非致死性心血管事件发生率。     

Neuronal differentiation is triggered by oleic acid synthesized and released by astrocytes

Unlike in the adult brain, the newborn brain specifically takes up serum albumin during the postnatal period, coinciding with the stage of maximal brain development. Here we report that albumin stimulates oleic acid synthesis by astrocytes from the main metabolic substrates available during brain development. Oleic acid released by astrocytes is used by neurons for the synthesis of phospholipids and is specifically incorporated into growth cones. Oleic acid promotes axonal growth, neuronal clustering, and expression of the axonal growth-associated protein-43, GAP-43; all these observations indicating neuronal differentiation. The effect of oleic acid on GAP-43 synthesis is brought about by the activation of protein kinase C, since it was prevented by inhibitors of this kinase, such as H-7, polymyxin or sphingosine. The expression of GAP-43 was significantly increased in neurons co-cultured with astrocytes by the presence of albumin indicating that neuronal differentiation takes place in the presence of oleic acid synthesized and released by astrocytes in situ. In conclusion, during brain development the presence of albumin could play an important role by triggering the synthesis and release of oleic acid by astrocytes, which induces neuronal differentiation.     

Oncogenes and inflammation rewire host energy metabolism in the tumor microenvironment

Here, we developed a model system to evaluate the metabolic effects of oncogene(s) on the host microenvironment. A matched set of “normal” and oncogenically transformed epithelial cell lines were co-cultured with human fibroblasts, to determine the “bystander” effects of oncogenes on stromal cells. ROS production and glucose uptake were measured by FACS analysis. In addition, expression of a panel of metabolic protein biomarkers (Caveolin-1, MCT1, and MCT4) was analyzed in parallel. Interestingly, oncogene activation in cancer cells was sufficient to induce the metabolic reprogramming of cancer-associated fibroblasts toward glycolysis, via oxidative stress. Evidence for “metabolic symbiosis” between oxidative cancer cells and glycolytic fibroblasts was provided by MCT1/4 immunostaining. As such, oncogenes drive the establishment of a stromal-epithelial “lactate-shuttle”, to fuel the anabolic growth of cancer cells. Similar results were obtained with two divergent oncogenes (RAS and NFκB), indicating that ROS production and inflammation metabolically converge on the tumor stroma, driving glycolysis and upregulation of MCT4. These findings make stromal MCT4 an attractive target for new drug discovery, as MCT4 is a shared endpoint for the metabolic effects of many oncogenic stimuli. Thus, diverse oncogenes stimulate a common metabolic response in the tumor stroma. Conversely, we also show that fibroblasts protect cancer cells against oncogenic stress and senescence by reducing ROS production in tumor cells. Ras-transformed cells were also able to metabolically reprogram normal adjacent epithelia, indicating that cancer cells can use either fibroblasts or epithelial cells as “partners” for metabolic symbiosis. The antioxidant N-acetyl-cysteine (NAC) selectively halted mitochondrial biogenesis in Ras-transformed cells, but not in normal epithelia. NAC also blocked stromal induction of MCT4, indicating that NAC effectively functions as an “MCT4 inhibitor”. Taken together, our data provide new strategies for achieving more effective anticancer therapy. We conclude that oncogenes enable cancer cells to behave as selfish “metabolic parasites”, like foreign organisms (bacteria, fungi, viruses). Thus, we should consider treating cancer like an infectious disease, with new classes of metabolically targeted “antibiotics” to selectively starve cancer cells. Our results provide new support for the “seed and soil” hypothesis, which was first proposed in 1889 by the English surgeon, Stephen Paget.     

The Plasma Membrane Calcium Pump in Pancreatic Cancer Cells Exhibiting the Warburg Effect Relies on Glycolytic ATP

Evidence suggests that the plasma membrane Ca²⁺-ATPase (PMCA), which is critical for maintaining a low intracellular Ca²⁺ concentration ([Ca²⁺]_i), utilizes glycolytically derived ATP in pancreatic ductal adenocarcinoma (PDAC) and that inhibition of glycolysis in PDAC cell lines results in ATP depletion, PMCA inhibition, and an irreversible [Ca²⁺]_i overload. We explored whether this is a specific weakness of highly glycolytic PDAC by shifting PDAC cell (MIA PaCa-2 and PANC-1) metabolism from a highly glycolytic phenotype toward mitochondrial metabolism and assessing the effects of mitochondrial versus glycolytic inhibitors on ATP depletion, PMCA inhibition, and [Ca²⁺]_i overload. The highly glycolytic phenotype of these cells was first reversed by depriving MIA PaCa-2 and PANC-1 cells of glucose and supplementing with α-ketoisocaproate or galactose. These culture conditions resulted in a significant decrease in both glycolytic flux and proliferation rate, and conferred resistance to ATP depletion by glycolytic inhibition while sensitizing cells to mitochondrial inhibition. Moreover, in direct contrast to cells exhibiting a high glycolytic rate, glycolytic inhibition had no effect on PMCA activity and resting [Ca²⁺]_i in α-ketoisocaproate- and galactose-cultured cells, suggesting that the glycolytic dependence of the PMCA is a specific vulnerability of PDAC cells exhibiting the Warburg phenotype.     

Mannitol metabolism in cultured plant cells

Non-structural storage carbohydrates were measured in 9-day-old barley ( Hordeum vulgare L. cv. Brant) primary leaves. Accumulation rates of starch, sucrose and total non-structural carbohydrates (TNC) were approximately linear when measured between 2- and 12-h of light. Progressively higher TNC accumulation rates were observed at higher irradiance levels (i.e., comparing 250, 550 and 1050 ·mol m⁻² s⁻¹). Synthesis of a low-molecular-weight fructan also was enhanced by high irradiances. Low irradiance treatments decreased leaf sucrose levels and there was a corresponding increase in the lag period preceding starch synthesis in the light. Increased starch accumulation rates were usually observed when sucrose concentrations were high. These and other results suggested that cytosolic sucrose concentrations affected starch metabolism in the chloroplast. However, sucrose accumulation rates increased and starch storage decreased when barley seedlings were transferred from 20 to 10°C during the light period. Lowering the night temperature from 20 to 10°C for a single dark period 8-days after planting increased the TNC content of barley primary leaves at the beginning of day nine. In this experiment, TNC accumulation rates of treated and untreated leaves were similar. Changes in the accumulation rate of TNC were usually observed within 2- to 4-h after barley seedlings were exposed to altered environmental conditions. Monitoring rapid changes in leaf carbohydrate levels is a sensitive method for assessing the effects of environmental treatments on photosynthetic metabolism.