Zinc protoporphyrin in the erythrocytes of patients with lead intoxication and iron deficiency anemia

The fluorescent porphyrin in the erythrocytes of patients with lead intoxication or with iron deficiency anemia is zinc protoporphyrin that is bound to globin moieties, probably at heme binding sites.     

Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization

Hepcidin is a peptide hormone secreted by the liver in response to iron loading and inflammation. Decreased hepcidin leads to tissue iron overload, whereas hepcidin overproduction leads to hypoferremia and the anemia of inflammation. Ferroportin is an iron exporter present on the surface of absorptive enterocytes, macrophages, hepatocytes, and placental cells. Here we report that hepcidin bound to ferroportin in tissue culture cells. After binding, ferroportin was internalized and degraded, leading to decreased export of cellular iron. The posttranslational regulation of ferroportin by hepcidin may thus complete a homeostatic loop: Iron regulates the secretion of hepcidin, which in turn controls the concentration of ferroportin on the cell surface.     

Iron-source preference of Staphylococcus aureus infections

Although bacteria use different iron compounds in vitGro, the possibility that microbes distinguish between these iron sources during infection has hitherto not been examined. We applied stable isotope labeling to detect source-specific iron by mass spectrometry and show that Staphylococcus aureus preferentially imports heme iron over transferrin iron. By combining this approach with computational genome analysis, we identified hts (heme transport system), a gene cluster that promotes preferred heme iron import by S. aureus. Heme iron scavenging by means of hts is required for staphylococcal pathogenesis in animal hosts, indicating that heme iron is the preferred iron source during the initiation of infection.     

Requirement of DNase II for definitive erythropoiesis in the mouse fetal liver

Mature erythrocytes in mammals have no nuclei, although they differentiate from nucleated precursor cells. The mechanism by which enucleation occurs is not well understood. Here we show that deoxyribonuclease II (DNase II) is indispensable for definitive erythropoiesis in mouse fetal liver. No live DNase II-null mice were born, owing to severe anemia. When mutant fetal liver cells were transferred into lethally irradiated wild-type mice, mature red blood cells were generated from the mutant cells, suggesting that DNase II functions in a non-cell-autonomous manner. Histochemical analyses indicated that the critical cellular sources of DNase II are macrophages present at the site of definitive erythropoiesis in the fetal liver. Thus, DNase II in macrophages appears to be responsible for destroying the nuclear DNA expelled from erythroid precursor cells.     

The Southern Ocean biological response to aeolian iron deposition

Biogeochemical rate processes in the Southern Ocean have an important impact on the global environment. Here, we summarize an extensive set of published and new data that establishes the pattern of gross primary production and net community production over large areas of the Southern Ocean. We compare these rates with model estimates of dissolved iron that is added to surface waters by aerosols. This comparison shows that net community production, which is comparable to export production, is proportional to modeled input of soluble iron in aerosols. Our results strengthen the evidence that the addition of aerosol iron fertilizes export production in the Southern Ocean. The data also show that aerosol iron input particularly enhances gross primary production over the large area of the Southern Ocean downwind of dry continental areas.     

Sex-linked anemia: a hypochromic anemia of mice

This hereditary anemia is most severe in young mice and tends to diminish with increasing age. Erythrocytes show great variation in size and form, with hypochromia and formation of target cells. Though the anemia occurs on a normal diet, it responds rapidly to iron-dextran injection. It may represent an unusual primary disturbance of iron metabolism.     

Epinephrine reduction of heme: implication for understanding the transmission of an agonist stimulus

Alpha-adrenergic agonists that promote platelet aggregation were found to reduce ferric heme to ferrous heme. Agents that bind iron in heme inhibited epinephrine-induced platelet aggregation. It is proposed that epinephrine first binds to its receptor and then reduces an adjacent heme group to transmit its agonist stimulus.     

补铁对白鼻子病貉血清·十二指肠和肝脏铁含量变化的影响

貉的白鼻子病发病率很高,对毛皮动物养殖业造成了较大的危害。研究发现白鼻子病貉有小细胞低色素性贫血和缺铁症。对白鼻子病患貉进行肌肉和口服2种途径补饲右旋糖酐铁发现,肌注补铁途径可以有效改善患貉贫血和缺铁症。这说明＂白鼻子＂病貉的低色素小细胞性贫血为缺铁性贫血,铁缺乏是由于肠道对铁的吸收障碍所致。     

Significance of mitochondria for porphyrin and heme biosynthesis

It is concluded that mitochondria are involved in three steps of porphyrin and heme biosynthesis-first, in the formation of delta-aminolevulinic acid from glycine and active succinate; second, in the synthesis of protoporphyrin; third, in the incorporation of iron into the porphyrin ring-that is, in heme formation.     

中国生物强化富铁小麦营养干预居民缺铁性贫血疾病负担分析

目前我国人口中平均每5人中就有1人遭受贫血危害,大部分居民贫血是由于铁营养素缺乏引起的,妇女和儿童是我国人口中铁营养素缺乏比较严重的群体,农村则是铁营养素缺乏的高发地区。针对我国高发的缺铁性贫血状况,重点讨论和分析了生物强化富铁小麦作为一种新的营养干预手段,其潜在的健康干预效果。在获取和依据相关材料和数据的基础上,采用失能调整生命年作为分析工具,研究确定了生物强化富铁小麦营养干预前后我国居民缺铁性贫血疾病负担的现状和潜在的营养改善情况。研究表明,生物强化富铁小麦具有很好的营养干预效果。最后提出加大对生物强化小麦育种研究的投入,培育含铁量更高的小麦新品种,并重视生物强化富铁小麦的推广应用的政策建议。     

Probing structure-function relations in heme-containing oxygenases and peroxidases

Structural factors that influence functional properties are examined in the case of four heme enzymes: cytochrome P-450, chloroperoxidase, horseradish peroxidase, and secondary amine mono-oxygenase. The identity of the axial ligand, the nature of the heme environment, and the steric accessibility of the heme iron and heme edge combine to play major roles in determining the reactivity of each enzyme. The importance of synthetic porphyrin models in understanding the properties of the protein-free metal center is emphasized. The conclusions described herein have been derived from studies at the interface between biological and inorganic chemistry.     

A steric mechanism for inhibition of CO binding to heme proteins

The crystal structures of myoglobin in the deoxy- and carbon monoxide-ligated states at a resolution of 1.15 angstroms show that carbon monoxide binding at ambient temperatures requires concerted motions of the heme, the iron, and helices E and F for relief of steric inhibition. These steps constitute the main mechanism by which heme proteins lower the affinity of the heme group for the toxic ligand carbon monoxide.     

Crystallographic and spectroscopic characterization of a nonheme Fe(IV)-O complex

Following the heme paradigm, it is often proposed that dioxygen activation by nonheme monoiron enzymes involves an iron(IV)=oxo intermediate that is responsible for the substrate oxidation step. Such a transient species has now been obtained from a synthetic complex with a nonheme macrocyclic ligand and characterized spectroscopically. Its high-resolution crystal structure reveals an iron-oxygen bond length of 1.646(3) angstroms, demonstrating that a terminal iron(IV)=oxo unit can exist in a nonporphyrin ligand environment and lending credence to proposed mechanisms of nonheme iron catalysis.     

试析我国蔬菜出口的现状与发展

我国的蔬菜出口在过去10年中取得了较大的发展,目前已与世界150个国家和地区建立了蔬菜出口贸易关系。蔬菜出口对于平衡农产品国际贸易收支,增加农民收入,和促进农村经济发展都具有重要的意义。在分析目前我国蔬菜出口现状和国际蔬菜发展前景的基础上,探讨了我国蔬菜出口的比较优势和存在的问题,提出了把出口蔬菜培育成为我国外向型农业支柱产业的对策建议。     

我国对虾产品贸易结构与出口竞争力分析

随着我国对虾养殖业的迅猛发展,对虾贸易也呈快速增长的趋势.我国是对虾贸易有较大顺差的国家,近年来对虾贸易顺差在逐渐拉大.对我国对虾出口贸易结构的分析表明,出口商品出现了由粗加工产品向深加工产品的结构转变:出口地区呈明显的沿海性分布;出口市场主要集中在日本、美国、欧盟、韩国和香港等传统市场.实证分析表明,我国对虾产品出口有中等比较优势,但我国的RCA和CA指数较其他主要对虾出口国明显落后.     

南极鱼类适应低温的分子进化研究进展

南大洋是地球上最冷的水域,水温常年在0℃以下,许多生物在南大洋降温过程中走向灭绝,而南极鱼亚目鱼类在南大洋逐渐变冷过程中快速进化,成为冰冻海域最繁盛的脊椎动物。随着越来越多的南极亚目鱼类基因组完成测序和分析,人们对这些鱼类在冰冻环境下生存和繁衍机制的认识也越来越深入和全面。本文从抗冻蛋白的起源、血液发生、抗过氧化机制、铁离子稳态调控、中性浮力的进化和基因组特征等方面综述了南极鱼类适应极端低温的分子进化及发育生物学机制,以期为鱼类抗冻与耐寒机制及适应性进化研究提供新的视角。     

Bilirubin inhibition of heme biosynthesis

The conversion of protoporphyrin and iron to heme is catalyzed by a soluble enzyme prepared from rat liver. This reaction is inhibited by bilirubin, and initial kinetic studies suggest that the inhibition is due in part to a competition between protoporphyrin and the bile pigment. Implications of this finding in hyperbilirubinemia are mentioned.     

Small phytoplankton and carbon export from the surface ocean

Autotrophic picoplankton dominate primary production over large oceanic regions but are believed to contribute relatively little to carbon export from surface layers. Using analyses of data from the equatorial Pacific Ocean and Arabian Sea, we show that the relative direct and indirect contribution of picoplankton to export is proportional to their total net primary production, despite their small size. We suggest that all primary producers, not just the large cells, can contribute to export from the surface layer of the ocean at rates proportional to their production rates.     

广西农产品进出口贸易十年(2000～2010年)变化史与发展对策

以广西历年农产品进出口数据为分析资料,结合定性方法进行研究.在2000 ～2010年间,广西农产品进出口发生了巨大变化,进口总额高速增长,出口总额增长相对平缓,贸易格局由顺差转为逆差,并逐年扩大.广西对东盟农产品进出口明显升温,一般贸易方式进出口份额逐步增加,边境小额贸易方式进出口份额明显减少.制约广西农产品进出口发展的主要因素是质量安全管理滞后、农产品深加工水平落后、农业科技含量和附加值较低及国外严格的技术壁垒.建议强化农产品生产质量安全管理及标准化建设,大力培植农产品出口龙头企业,调整优化农产品出口商品结构和完善多层次的农产品出口促进体系,促进广西农产品进出口发展.